Preparation method of polyimide graphitized film

Abstract

The invention relates to the technical field of graphitized membranes, and discloses a preparation method of a polyimide graphitized membrane, which comprises the following steps: reacting a diamine monomer, a dianhydride monomer, an intermediate 2 and an aminated multi-walled carbon nanotube to obtain a polyimide precursor membrane; and carrying out high-temperature heat treatment to obtain the polyimide graphitized film. The multi-walled carbon nanotube structure in the polyimide graphitized film is grafted and modified, a large number of benzene rings and amino groups are introduced, and the conductive and heat-conducting effects of the polyimide graphitized film are improved by adding the multi-walled carbon nanotube structure into the polyimide graphitized film; bromine in the intermediate 1 reacts with boric acid groups in 4-aminophenylboronic acid, so that the substitution degree of benzene rings and amino groups is improved, the bromine and benzene rings in the aminated multi-walled carbon nanotubes form a larger plane, and meanwhile, heat is transferred more effectively; the aminated multi-walled carbon nanotubes and amino groups in the intermediate 2 form a large number of nitrogen sources, and graphene doping and high-temperature treatment improve the conductivity of the polyimide graphitized film.

Description

Technical Field

[0001] The invention relates to the technical field of graphitized films, in particular to a method for preparing a polyimide graphitized film. Background Art

[0002] Polyimide has many excellent properties and is widely used in electronics, aviation, communications and other fields. Traditional graphite films prepared from polyimide have low graphitization rate, large fluctuations in mechanical properties and unsatisfactory thermal conductivity, which limit their industrial applications. For example, patent CN118439878A discloses a high thermal conductivity polyimide composite graphite film and a preparation method thereof. The polyimide composite graphite film obtained by the invention has a high degree of graphitization and excellent lateral and longitudinal thermal conductivity, but its electrical conductivity is not improved. Summary of the invention

[0003] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a method for preparing a polyimide graphitized film, which has good thermal and electrical conductivity effects.

[0004] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: a method for preparing a polyimide graphitized film, the method for preparing a polyimide graphitized film comprising the following steps: (1) Add 3,3'-dibromo-4,4'-biphenol and 1,2,4,5-tetrabromobenzene to a reactor containing acetone solvent, stir to dissolve, then continue to add potassium carbonate, reflux at 40-60°C for 8-10 hours, cool to room temperature after reaction, filter, wash with distilled water, and dry to obtain intermediate 1; (2) Add intermediate 1 and 4-aminophenylboronic acid to 1,4-dioxane solvent, introduce nitrogen protection, continue to add triphenylphosphine palladium catalyst, raise the temperature to 55-70°C and react for 4-6 hours. After the reaction, distill, filter 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 to N,N-dimethylformamide solvent, stir and mix, add 2-6 parts by weight of intermediate 2 and 3-7 parts by weight of amino multi-walled carbon nanotubes to obtain a solution A with a mass fraction of 20-25%, and then apply solution A on glass. The solution A layer on the glass is dried at 60-75°C for 1-1.5h in a curing oven, and then heated in stages in a high-temperature oven, heating at 150-155°C for 1-1.2h, 200-210°C for 1-1.5h, 250-260°C for 1-1.2h, and 350-360°C for 1-1.5h to obtain a polyimide precursor film; (4) The polyimide precursor film is clamped on a graphite plate, and the temperature is raised to 1000°C at a rate of 16-17°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 7-8°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 2-3°C / min in a pressurized argon environment of 0.08 MPa. The temperature is maintained at the maximum temperature for 1-1.5 hours, and then cooled to obtain a polyimide graphitized film.

[0005] Preferably, the mass ratio of 3,3'-dibromo-4,4'-biphenol, 1,2,4,5-tetrabromobenzene and potassium carbonate in (1) is 1:1.2-1.6:0.2-0.3.

[0006] Preferably, the mass ratio of the intermediate 1, 4-aminophenylboronic acid, and triphenylphosphine palladium catalyst in (2) is 0.7-0.9:1:0.01-0.02.

[0007] Preferably, the preparation method of the aminated multi-walled carbon nanotubes in (3) is as follows: multi-walled carbon nanotubes and p-nitrobenzoic acid are added to polyphosphoric acid, magnetically stirred until uniformly dispersed, and mechanically stirred at 115-125° C. for 1-2 hours, then the temperature is cooled to 40-55° C. and stannous chloride is added thereto to react for 2-4 hours, and then cooled to room temperature, washed with deionized water, and vacuum dried to obtain aminated multi-walled carbon nanotubes.

[0008] 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.

[0009] 3. Beneficial technical effects The present invention carries out a substitution reaction between the phenolic hydroxyl group 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 an intermediate 1; the bromine in the intermediate 1 reacts with the boronic acid group in 4-aminophenylboric acid to introduce a large number of benzene ring structures and amino groups, thereby obtaining an intermediate 2; the hydroxyl group in the multi-walled carbon nanotube and the carboxyl group in p-nitrobenzoic acid are subjected to an esterification reaction to introduce a nitro group; stannous chloride is added for reaction to generate an amino group, thereby obtaining an amination multi-walled carbon nanotube; a diamine monomer, a dibasic anhydride monomer, the intermediate 2 and the amination multi-walled carbon nanotube are reacted to obtain a polyimide precursor film; and a high-temperature heat treatment is performed to obtain a polyimide graphitized film.

[0010] The multi-walled carbon nanotube structure in the polyimide graphitized film of the present invention is grafted and modified, a large number of benzene rings and amino groups are introduced, and the agglomeration of the multi-walled carbon nanotubes is reduced. The addition of the multi-walled carbon nanotubes to the polyimide graphitized film improves its electrical and thermal conductivity; the bromine in the intermediate 1 reacts with the boric acid group in 4-aminophenylboronic acid, thereby increasing the substitution degree of the benzene ring and the amino group, and forms a larger plane with the benzene ring in the aminated multi-walled carbon nanotubes, the skeleton structure is relatively flat, the mechanical properties of the polyimide graphitized film are improved, and heat is more effectively transferred; the amino groups in the aminated multi-walled carbon nanotubes and the intermediate 2 constitute a large number of nitrogen sources, and the conductivity of the polyimide graphitized film is improved by doping graphene and high-temperature treatment. DETAILED DESCRIPTION Example 1

[0011] (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, wherein the mass ratio of 3,3'-dibromo-4,4'-biphenol, 1,2,4,5-tetrabromobenzene and potassium carbonate is 1:1.2:0.2, reflux at 40°C for 8h, cool to room temperature after completion, filter, wash with distilled water, and dry to obtain intermediate 1; (2) Add intermediate 1 and 4-aminophenylboronic acid to 1,4-dioxane solvent, introduce nitrogen protection, and continue to add triphenylphosphine palladium catalyst, wherein the mass ratio of intermediate 1, 4-aminophenylboronic acid and triphenylphosphine palladium catalyst is 0.7:1:0.01, heat to 55°C and react for 4 hours. After the reaction, distill, filter and dry to obtain intermediate 2; (3) adding multi-walled carbon nanotubes and p-nitrobenzoic acid to polyphosphoric acid, stirring magnetically until uniformly dispersed, continuing mechanical stirring at 115°C for 1 hour, then cooling the temperature to 40°C and adding stannous chloride to react for 2 hours, wherein the mass ratio of multi-walled carbon nanotubes, p-nitrobenzoic acid, polyphosphoric acid, and stannous chloride is 1:8:55:30, cooling to room temperature, washing with deionized water, and vacuum drying to obtain amino-modified multi-walled carbon nanotubes; (4) Add 15 parts by weight of 2-methyl-p-phenylenediamine and 20 parts by weight of biphenyl dianhydride to N,N-dimethylformamide solvent, stir and mix, add 2 parts by weight of intermediate 2 and 3 parts by weight of amino-modified multi-walled carbon nanotubes thereto, and obtain a solution A with a mass fraction of 20%, and then apply solution A on glass. The solution A layer on the glass is dried at 60°C for 1 hour in a curing oven, and then heated in a high-temperature oven in stages, heating at 150°C for 1 hour, 200°C for 1 hour, 250°C for 1 hour, and 350°C for 1 hour to obtain a polyimide precursor film; (5) The polyimide precursor film is sandwiched between a graphite plate and pretreated by heating the film at a rate of 16°C / min to 1000°C under reduced pressure in an ultra-high temperature furnace equipped with a graphite heater. Next, the film is heated at a rate of 7°C / min to 2700°C in an ultra-high temperature furnace in a pressurized argon atmosphere of 0.08 MPa. The film is then heated at a rate of 2°C / min to a maximum temperature of 2800°C in a pressurized argon atmosphere of 0.08 MPa. The film is maintained at the maximum temperature for 1 hour and then cooled to obtain a graphitized polyimide film. Example 2

[0012] (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, wherein the mass ratio of 3,3'-dibromo-4,4'-biphenol, 1,2,4,5-tetrabromobenzene and potassium carbonate is 1:1.6:0.3, reflux at 60°C for 10 hours, cool to room temperature after completion, filter, wash with distilled water, and dry to obtain intermediate 1; (2) Add intermediate 1 and 4-aminophenylboronic acid to 1,4-dioxane solvent, introduce nitrogen protection, and continue to add triphenylphosphine palladium catalyst, wherein the mass ratio of intermediate 1, 4-aminophenylboronic acid and triphenylphosphine palladium catalyst is 0.9:1:0.02, heat to 70°C and react for 6 hours. After the reaction, distill, filter and dry to obtain intermediate 2; (3) Add multi-walled carbon nanotubes and p-nitrobenzoic acid to polyphosphoric acid, stir magnetically until uniformly dispersed, continue mechanical stirring at 125°C for 2 hours, then cool to 55°C and add stannous chloride to react for 4 hours, wherein 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 vacuum dry to obtain amino-modified multi-walled carbon nanotubes; (4) Add 30 parts by weight of 2-methyl-p-phenylenediamine and 35 parts by weight of biphenyl dianhydride to N,N-dimethylformamide solvent, stir and mix, add 6 parts by weight of intermediate 2 and 7 parts by weight of amino-modified multi-walled carbon nanotubes thereto, and obtain a solution A with a mass fraction of 25%, and then apply solution A on glass. The solution A layer on the glass is dried at 75°C for 1.5 hours in a curing oven, and then heated in stages in a high-temperature oven, heating at 155°C for 1.2 hours, 210°C for 1.5 hours, 260°C for 1.2 hours, and 360°C for 1.5 hours to obtain a polyimide precursor film; (5) The polyimide precursor film is clamped on a graphite plate and pretreated by heating the film at a rate of 17°C / min to 1000°C under reduced pressure in an ultra-high temperature furnace with a graphite heater. Next, the film is heated at a rate of 8°C / min to 2700°C in an ultra-high temperature furnace in a pressurized argon environment of 0.08 MPa. The film is then heated at a rate of 3°C / min to a maximum temperature of 2800°C in a pressurized argon environment of 0.08 MPa. The film is maintained at the maximum temperature for 1.5 h and then cooled to obtain a polyimide graphitized film. Example 3

[0013] (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, wherein the mass ratio of 3,3'-dibromo-4,4'-biphenol, 1,2,4,5-tetrabromobenzene and potassium carbonate is 1:1.4:0.25, reflux at 50°C for 9 hours, cool to room temperature after completion, filter, wash with distilled water, and dry to obtain intermediate 1; (2) Add intermediate 1 and 4-aminophenylboronic acid to 1,4-dioxane solvent, introduce nitrogen protection, and continue to add triphenylphosphine palladium catalyst, wherein the mass ratio of intermediate 1, 4-aminophenylboronic acid and triphenylphosphine palladium catalyst is 0.5:1:0.015, heat to 62°C and react for 5 hours. After the reaction, distill, filter and dry to obtain intermediate 2; (3) Add multi-walled carbon nanotubes and p-nitrobenzoic acid to polyphosphoric acid, stir magnetically until uniformly dispersed, continue mechanical stirring at 120°C for 1.5 hours, then cool to 50°C and add stannous chloride to react for 3 hours, wherein the mass ratio of multi-walled carbon nanotubes, p-nitrobenzoic acid, polyphosphoric acid and stannous chloride is 1:9:57.5:32.5. After the reaction, cool to room temperature, wash with deionized water, and vacuum dry to obtain amino-modified multi-walled carbon nanotubes; (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-modified multi-walled carbon nanotubes thereto, and obtain a solution A with a mass fraction of 22.5%, and then apply solution A on glass. The solution A layer on the glass is dried at 67°C for 1.25 h in a curing oven, and then heated in stages in a high-temperature oven, heating 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; (5) The polyimide precursor film is clamped on a graphite plate and pretreated by heating the film at a rate of 16.5°C / min to 1000°C under reduced pressure in an ultra-high temperature furnace with a graphite heater. Next, the film is heated at a rate of 7.5°C / min to 2700°C in an ultra-high temperature furnace in a pressurized argon environment of 0.08 MPa. The film is then heated at a rate of 2.5°C / min to a maximum temperature of 2800°C in a pressurized argon environment of 0.08 MPa. The film is maintained at the maximum temperature for 1.3 h and then cooled to obtain a polyimide graphitized film.

[0014] Comparative Example 1 (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, wherein the mass ratio of 3,3'-dibromo-4,4'-biphenol, 1,2,4,5-tetrabromobenzene and potassium carbonate is 1:1.4:0.25, reflux at 50°C for 9 hours, cool to room temperature after completion, filter, wash with distilled water, and dry to obtain intermediate 1; (2) Add intermediate 1 and 4-aminophenylboronic acid to 1,4-dioxane solvent, introduce nitrogen protection, and continue to add triphenylphosphine palladium catalyst, wherein the mass ratio of intermediate 1, 4-aminophenylboronic acid and triphenylphosphine palladium catalyst is 0.5:1:0.015, heat to 62°C and react for 5 hours. After the reaction, distill, filter and dry to obtain intermediate 2; (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, add 4 parts by weight of intermediate 2 thereto, and obtain a solution A with a mass fraction of 22.5%, and then apply solution A on glass. The solution A layer on the glass is dried at 67° C. for 1.25 h in a curing oven, and then heated in stages in a high-temperature oven, heating 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; (4) 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.

[0015] Comparative Example 2 (1) Add multi-walled carbon nanotubes and p-nitrobenzoic acid to polyphosphoric acid, stir magnetically until uniformly dispersed, continue mechanical stirring at 120°C for 1.5 hours, then cool to 50°C and add stannous chloride to react for 3 hours, wherein the mass ratio of multi-walled carbon nanotubes, p-nitrobenzoic acid, polyphosphoric acid and stannous chloride is 1:9:57.5:32.5. After the reaction, cool to room temperature, wash with deionized water, and vacuum dry to obtain amino-modified multi-walled carbon nanotubes; (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, add 5 parts by weight of amino-modified multi-walled carbon nanotubes thereto, and obtain a solution A with a mass fraction of 22.5%, and then apply solution A on glass. The solution A layer on the glass is dried at 67°C for 1.25 hours in a curing oven, and then heated in stages in a high-temperature oven, heating at 153°C for 1.1 hours, 205°C for 1.2 hours, 255°C for 1.1 hours, and 355°C for 1.3 hours to obtain a polyimide precursor film; (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.

[0016] Performance Testing The electrical conductivity of the polyimide graphitized film was tested, and the thermal conductivity was tested according to the ASTM E1461-13 standard.

[0017] Table 1: Electrical conductivity and thermal conductivity test.

[0018]

[0019] 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.

[0020] 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 method for preparing a polyimide graphitized film, It is characterized in that The method for preparing the polyimide graphitized film comprises the following steps: (1) Add 3,3'-dibromo-4,4'-biphenol and 1,2,4,5-tetrabromobenzene to a reactor containing acetone solvent, stir to dissolve, then continue to add potassium carbonate, reflux at 40-60°C for 8-10 hours, cool to room temperature after reaction, filter, wash with distilled water, and dry to obtain intermediate 1; (2) Add intermediate 1 and 4-aminophenylboronic acid to 1,4-dioxane solvent, introduce nitrogen protection, continue to add triphenylphosphine palladium catalyst, raise the temperature to 55-70°C and react for 4-6 hours. After the reaction, distill, filter 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 to N,N-dimethylformamide solvent, stir and mix, add 2-6 parts by weight of intermediate 2 and 3-7 parts by weight of amino multi-walled carbon nanotubes to obtain solution A, and then apply solution A on glass. The solution A layer on the glass is dried at 60-75°C for 1-1.5 hours using a curing oven, and then heated in stages using a high-temperature oven, heating at 150-155°C for 1-1.2 hours, heating at 200-210°C for 1-1.5 hours, heating at 250-260°C for 1-1.2 hours, and heating at 350-360°C for 1-1.5 hours to obtain a polyimide precursor film; (4) The polyimide precursor film is clamped on a graphite plate, and the temperature is raised to 1000°C at a rate of 16-17°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 7-8°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 2-3°C / min in a pressurized argon environment of 0.08 MPa. The temperature is maintained at the maximum temperature for 1-1.5 hours, and then cooled to obtain a polyimide graphitized film.

2. The method for preparing a graphitized polyimide film according to claim 1, It is characterized in that The mass ratio of 3,3'-dibromo-4,4'-biphenol, 1,2,4,5-tetrabromobenzene and potassium carbonate in (1) is 1:1.2-1.6:0.2-0.

3.

3. The method for preparing a graphitized polyimide film according to claim 1, It is characterized in that The mass ratio of the intermediate 1, 4-aminophenylboronic acid and triphenylphosphine palladium catalyst in (2) is 0.7-0.9:1:0.01-0.

02.

4. The method for preparing a graphitized polyimide film according to claim 1, It is characterized in that The mass fraction of solution A in (3) is 20-25%.

5. The method for preparing a graphitized polyimide film according to claim 1, It is characterized in that The preparation method of the aminated multi-walled carbon nanotubes in (3) is as follows: multi-walled carbon nanotubes and p-nitrobenzoic acid are added to polyphosphoric acid, magnetically stirred until uniformly dispersed, mechanically stirred, then cooled to 40-55°C and stannous chloride is added thereto for reaction for 2-4 hours, then cooled to room temperature, washed with deionized water, and vacuum dried to obtain aminated multi-walled carbon nanotubes.

6. The method for preparing a graphitized polyimide film according to claim 5, It is characterized in that 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.

7. The method for preparing a graphitized polyimide film according to claim 5, It is characterized in that The temperature of the mechanical stirring is 115-125°C.

8. The method for preparing a graphitized polyimide film according to claim 5, It is characterized in that The mechanical stirring time is 1-2h.

Images