CN114516959B

CN114516959B - Polyamide film, method for producing same, and graphite film

Info

Publication number: CN114516959B
Application number: CN202210258655.3A
Authority: CN
Inventors: 李冠纬; 苏赐祥
Original assignee: Guangdong Hongxiang Technology Co ltd
Current assignee: Guangdong Hongxiang Technology Co ltd
Priority date: 2022-03-16
Filing date: 2022-03-16
Publication date: 2023-07-14
Anticipated expiration: 2042-03-16
Also published as: CN114516959A

Abstract

The present application provides a polyamide membrane comprising a polyamide polymer. The polyamide polymer comprises the reaction product of a diamine monomer comprising N, N-bis (4-aminophenyl) -N, N-diphenyl-1, 4-phenylenediamine and a dicarboxylic acid monomer. The polyamide film can be used for preparing a graphite film with a thicker thickness. The application also provides a graphite film prepared from the polyamide film and a preparation method of the polyamide film.

Description

Polyamide film, method for producing same, and graphite film

Technical Field

The application relates to the field of heat dissipation materials, in particular to a polyamide membrane, a graphite membrane applying the polyamide membrane and a preparation method of the polyamide membrane.

Background

The artificial graphite film is a common heat dissipation material for electronic products due to its high heat dissipation coefficient and low density. The artificial graphite film is generally produced by carbonizing, graphitizing and calendaring a polyamide film. The carbon content of the graphitized polyamide film is low, and the thickness of the graphitized polyamide film is greatly reduced when the graphitized polyamide film is subjected to the casting, so that the thickness of the prepared graphite film is low. The graphite film is matched with a heat conducting material to be used as a heat radiating material of an electronic product. However, the graphite film and the heat conductive material easily generate a thermal interface and the like, and the heat dissipation effect is reduced. Therefore, a graphite film having a high thickness needs to be produced.

Disclosure of Invention

In view of the above, it is necessary to provide a polyamide film that can be applied to the production of a graphite film of high thickness and a method for producing the same.

The present application provides a polyamide membrane comprising a polyamide polymer. The polyamide polymer comprises the reaction product of a diamine monomer comprising N, N-bis (4-aminophenyl) -N, N-diphenyl-1, 4-phenylenediamine and a dicarboxylic acid monomer.

The application also provides a graphite film, which is prepared from the polyamide film through carbonization and graphitization treatment.

The application also provides a preparation method of the polyamide membrane, which comprises the following steps:

dissolving diamine monomer and dicarboxylic acid monomer in an organic solvent to obtain a reaction solution;

adding 3-methylpyridine and triphenyl phosphite into the reaction solution, and stirring the mixture in a nitrogen environment to react to obtain a mixed solution;

pouring the mixed solution into methanol to separate out to obtain polyamide composition solid;

dissolving the polyamide composition solid and a catalyst in an organic solvent to obtain a polyamide solution;

coating the polyamide solution on a supporting plate to obtain a polyamide coating film;

and baking and curing the polyamide coating film to obtain the polyamide film.

In the application, N, N-bis (4-aminophenyl) -N, N-diphenyl-1, 4-phenylenediamine has a plurality of heat-resistant benzene ring structures, and bonds among benzene rings are nitrogen elements, so that the prepared polyamide polymer has high carbon residue rate (high heat resistance), and further the prepared polyamide film has high carbon content after graphitization, so that the graphitized polyamide film has small thickness change after calendaring, and further the graphite film with high thickness can be prepared. In addition, the N, N-bis (4-aminophenyl) -N, N-diphenyl-1, 4-phenylenediamine has huge side chain groups with a multi-benzene ring structure, so that the free radicals among molecules are increased, the gas dissipation and the solvent volatilization are facilitated, and the production efficiency is further improved; and during subsequent carbonization or graphitization, foaming can be performed through the channel, so that the appearance of the graphite film is improved.

Detailed Description

The following will clearly and fully describe the technical solutions in the embodiments of the present application, and it is obvious that the described embodiments are only some of the embodiments of the present application, but not all of the embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the inventor based on the embodiments herein, are within the scope of the protection of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

An embodiment of the present application provides a polyamide membrane comprising a polyamide polymer. The polyamide polymer comprises the reaction product of a diamine monomer and a dicarboxylic acid monomer. The diamine monomer comprises N, N-bis (4-aminophenyl) -N, N-diPhenyl-1, 4-phenylenediamine (ENP SDA). The structural formula of the N, N-bis (4-aminophenyl) -N, N-diphenyl-1, 4-phenylenediamine is

The dicarboxylic acid monomer may be any commercially available dicarboxylic acid monomer. In some embodiments, the dicarboxylic acid monomer is a dicarboxylic acid monomer having a multi-benzene ring structure, for example, the dicarboxylic acid monomer includes at least one of 2, 6-naphthalene dicarboxylic acid (NPDA), 4 '-diphenyl ether dicarboxylic acid (ODBA), biphenyl dicarboxylic acid (BPCA), 1, 4-phthalic acid (PTA), 1, 3-phthalic acid (IPA), and 4,4' -sulfonyl dibenzoic acid (SFDA).

As used herein, the term "reaction product" refers to a product formed from one or more synthetic steps. In general, the reaction that can be used to form the polyamide polymer as a reaction product can comprise at least a polymerization reaction. In some embodiments, the reaction product may be formed by reacting a diamine monomer and a dicarboxylic acid monomer via polymerization.

In some embodiments, the molar ratio of the dicarboxylic acid monomer to the diamine monomer is from 0.9 to 1.1.

The diamine monomer may also include any commercially available diamine monomer, with ENPSDA comprising greater than 90% of the total moles of diamine monomer. In some embodiments, the diamine monomer further includes commercially available diamine monomers having a multi-benzene ring structure, such as diaminodiphenyl ether (ODA).

An embodiment of the present application also provides a method for preparing the above polyamide film, which includes the following steps:

and baking and curing the polyamide coating film to obtain the polyamide film.

The polyamide solution includes the polyamide polymer and the organic solvent, in which the polyamide polymer is dissolved. In some embodiments, the organic solvent comprises 80 to 85% by weight of the polyamide solution, in other words, the polyamide solution has a solids content of 15 to 20%.

In some embodiments, the catalyst has a particle size of less than 1.5 μm and comprises from 0.02 to 0.5% by weight of the polyamide polymer.

The catalyst may be any commercially available inorganic or organic catalyst. In some embodiments, the organic catalyst comprises at least one of graphene, carbon black, carbon nanotubes, and fullerenes, and the inorganic catalyst comprises at least one of calcium bicarbonate, calcium hydrogen phosphate, barium dihydrogen phosphate, potassium hydrogen carbonate, potassium dihydrogen phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, boron phosphate, calcium carbide, copper oxide, ferric oxide, and aluminum oxide.

In some embodiments, the organic solvent includes at least one of dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), and N, N-Dimethylformamide (DMF).

It will be appreciated that after the reaction solution is poured into methanol to precipitate, filtration is also performed to take out a solid, and the solid is purified by methanol to obtain the polyamide composition solid.

It will be appreciated that the step of baking the polyamide coating film is further comprised of: and peeling the cured polyamide coating film from the supporting plate to obtain a self-supporting polyamide coating film, and then carrying out biaxial stretching and heat treatment on the self-supporting polyamide coating film to obtain the polyamide film.

In some embodiments, the bake cure temperature is 120 to 170 ℃, the bake cure time is 20 to 30 minutes, and the heat treatment temperature is 400 to 450 ℃. The solvent content of the self-supporting polyamide coating film is 25-30%. After the polyamide solution is coated, the self-supporting polyamide coating film can be obtained by drying at a lower temperature, high-temperature treatment is not needed, and the limit of production equipment (such as a machine) can be reduced. The polyamide has intermolecular hydrogen bonds, so that the self-supporting polyamide coating film has good toughness, and the self-supporting polyamide coating film can be biaxially stretched. Through high-temperature heat treatment, the crystallization compliance and arrangement compactness of the polyamide film can be improved, the intermolecular defects are reduced, and the properties of the graphite film are further improved.

An embodiment of the present application also provides a graphite film, which is prepared from the polyamide film after carbonization and graphitization treatment.

And carbonizing the polyamide film to form a carbonized film, wherein the carbonized film catalyzes graphitization reaction to form the graphite film through the catalyst. The catalyst can reduce graphitization activity and promote graphitization reaction of the carbonized film to form a graphite film. The catalyst is added when forming the polyamide solution, so that the dispersion uniformity of the catalyst can be improved.

In the application, the ENPSDA has a plurality of heat-resistant benzene ring structures, and bonds among benzene rings are nitrogen elements, so that the prepared polyamide polymer has high carbon residue rate (high heat resistance), and further the prepared polyamide film has high carbon content after graphitization, so that the thickness change of the graphitized polyamide film after calendaring is smaller, and further the graphite film with higher thickness can be prepared. In addition, the prepared polyamide film has high carbon content (comprising nitrogen element or benzene ring structure) after high-temperature carbonization, so that the defect amount after carbonization can be reduced, and the diffusion of carbon element during subsequent graphitization is facilitated. In addition, the nitrogen element in the ENPSDA is uniformly distributed, and the catalyst is added into the polyamide film, so that the graphitization is uniformly performed in the subsequent graphitization, and the graphite film has good appearance.

In addition, ENPSDA has huge side chain groups with a multi-benzene ring structure, so that free radicals among molecules are increased, gas dissipation and solvent volatilization are facilitated, and the production efficiency is further improved; and during subsequent carbonization or graphitization, foaming can be performed through the channel, so that the appearance of the graphite film is improved.

The polyamide film of the present application will be described below by way of specific examples.

Example 1

Diamine ENPSDA (0.1 mol,44.22 g), dicarboxylic acid NPDA (0.1 mol,21.62 g) and solvent NMP (197.52 g) were added to a 500ml reaction flask, and dissolved by stirring under nitrogen atmosphere for 1 hour, then 3-methylpyridine (1 mol,93.13 g) and triphenyl phosphite (0.21 mol,65.16 g) were added, and the temperature was raised to 100 to 110℃and stirred under nitrogen atmosphere for 12 hours to obtain a mixed solution. The mixed solution is poured into methanol to precipitate, and then filtered to obtain a solid, and then the solid is purified by methanol to obtain a polyamide composition solid.

Example 2

Into a 500ml reaction flask were charged diamine ENPSDA (0.09 mol,39.8 g), diamine ODA (0.01 mol,2.00 g), dicarboxylic acid NPDA (0.1 mol,21.62 g) and solvent NMP (190.26 g), and the mixture was dissolved by stirring under nitrogen for 1 hour, then 3-methylpyridine (1 mol,93.13 g) and triphenyl phosphite (0.21 mol,65.16 g) were added, and the temperature was raised to 100 to 110℃and the mixture was stirred under nitrogen for 12 hours to obtain a mixed solution. The mixed solution is poured into methanol to precipitate, and then filtered to obtain a solid, and then the solid is purified by methanol to obtain a polyamide composition solid.

Example 3

In a 500ml reaction flask, diamine ENPSDA (0.1 mol,44.2 g), dicarboxylic acid ODBA (0.1 mol,25.82 g) and solvent NMP (210.13 g) were added, and stirred under nitrogen atmosphere for 1 hour to dissolve, then 3-methylpyridine (1 mol,93.13 g) and triphenyl phosphite (0.21 mol,65.16 g) were added, and the temperature was raised to 100 to 110℃and stirred under nitrogen atmosphere for 12 hours to obtain a mixed solution. The mixed solution is poured into methanol to precipitate, and then filtered to obtain a solid, and then the solid is purified by methanol to obtain a polyamide composition solid.

Example 4

Into a 500ml reaction flask were charged diamine ENPSDA (0.09 mol,39.8 g), diamine ODA (0.01 mol,2.00 g), dicarboxylic acid ODBA (0.1 mol,25.82 g) and solvent NMP (202.87 g), and the mixture was dissolved by stirring under nitrogen for 1 hour, then 3-methylpyridine (1 mol,93.13 g) and triphenyl phosphite (0.21 mol,65.16 g) were added, and the temperature was raised to 100 to 110℃and the mixture was stirred under nitrogen for 12 hours to obtain a mixed solution. The mixed solution is poured into methanol to precipitate, and then filtered to obtain a solid, and then the solid is purified by methanol to obtain a polyamide composition solid.

Example 5

Diamine ENPSDA (0.1 mol,44.22 g), dicarboxylic acid BPCA (0.1 mol,24.22 g) and solvent NMP (205.33 g) were added to a 500ml reaction flask, and dissolved by stirring under nitrogen atmosphere for 1 hour, then 3-methylpyridine (1 mol,93.13 g) and triphenyl phosphite (0.21 mol,65.16 g) were added, and the temperature was raised to 100 to 110℃and stirred under nitrogen atmosphere for 12 hours to obtain a mixed solution. The mixed solution is poured into methanol to precipitate, and then filtered to obtain a solid, and then the solid is purified by methanol to obtain a polyamide composition solid.

Example 6

Into a 500ml reaction flask were charged diamine ENPSDA (0.09 mol,39.8 g), diamine ODA (0.01 mol,2.00 g), dicarboxylic acid BPCA (0.1 mol,24.22 g) and solvent NMP (198.07 g), and the mixture was dissolved by stirring under nitrogen for 1 hour, then 3-methylpyridine (1 mol,93.13 g) and triphenyl phosphite (0.21 mol,65.16 g) were added, and the temperature was raised to 100 to 110℃and the mixture was stirred under nitrogen for 12 hours to obtain a mixed solution. The mixed solution is poured into methanol to precipitate, and then filtered to obtain a solid, and then the solid is purified by methanol to obtain a polyamide composition solid.

Example 7

Into a 500ml reaction flask, diamine ENPSDA (0.1 mol,44.22 g), dicarboxylic acid IPA (0.1 mol,16.61 g) and solvent NMP (182.50 g) were added, and stirred under nitrogen atmosphere for 1 hour to dissolve, then 3-methylpyridine (1 mol,93.13 g) and triphenyl phosphite (0.21 mol,65.16 g) were added, and the temperature was raised to 100 to 110℃and stirred under nitrogen atmosphere for 12 hours to obtain a mixed solution. The mixed solution is poured into methanol to precipitate, and then filtered to obtain a solid, and then the solid is purified by methanol to obtain a polyamide composition solid.

Example 8

Into a 500ml reaction flask were charged diamine ENPSDA (0.09 mol,39.8 g), diamine ODA (0.01 mol,2.00 g), dicarboxylic acid IPA (0.1 mol,16.61 g) and solvent NMP (175.24 g), and the mixture was dissolved by stirring under nitrogen for 1 hour, then 3-methylpyridine (1 mol,93.13 g) and triphenyl phosphite (0.21 mol,65.16 g) were added, and the temperature was raised to 100 to 110℃and the mixture was stirred under nitrogen for 12 hours to obtain a mixed solution. The mixed solution is poured into methanol to precipitate, and then filtered to obtain a solid, and then the solid is purified by methanol to obtain a polyamide composition solid.

Comparative example 1

Diamine ODA (0.1 mol,20.02 g), catalyst (0.0084 g), dianhydride pyromellitic dianhydride (PMDA) (0.1 mol,21.81 g) and solvent NMP (167.34 g) were added to a 500ml reaction flask to obtain a mixed solution with a solid content of 15 to 20%, and the mixed solution was stirred under nitrogen for 24 hours to obtain a polyamic acid solution.

Comparative example 2

Into a 500ml reaction flask were charged diamine ENPSDA (0.085 mol,37.59 g), diamine ODA (0.015 mol,3.00 g), dicarboxylic acid NPDA (0.1 mol,21.62 g) and solvent NMP (186.63 g), and then dissolved by stirring under nitrogen atmosphere for 1 hour, and then 3-methylpyridine (1 mol,93.13 g) and triphenyl phosphite (0.21 mol,65.16 g) were added, and the temperature was raised to 100 to 110℃and stirred under nitrogen atmosphere for 12 hours to obtain a mixed solution. The mixed solution is poured into methanol to precipitate, and then filtered to obtain a solid, and then the solid is purified by methanol to obtain a polyamide composition solid.

Comparative example 3

Into a 500ml reaction flask were charged diamine ENPSDA (0.085 mol,37.59 g), diamine ODA (0.015 mol,3.00 g), dicarboxylic acid ODBA (0.1 mol,25.82 g) and solvent NMP (199.24 g), and the mixture was dissolved by stirring under nitrogen for 1 hour, then 3-methylpyridine (1 mol,93.13 g) and triphenyl phosphite (0.21 mol,65.16 g) were added, and the temperature was raised to 100 to 110℃and the mixture was stirred under nitrogen for 12 hours to obtain a mixed solution. The mixed solution is poured into methanol to precipitate, and then filtered to obtain a solid, and then the solid is purified by methanol to obtain a polyamide composition solid.

Comparative example 4

Into a 500ml reaction flask were charged diamine ENPSDA (0.085 mol,37.59 g), diamine ODA (0.015 mol,3.00 g), dicarboxylic acid BPCA (0.1 mol,24.22 g) and solvent NMP (194.44 g), and then dissolved by stirring under nitrogen atmosphere for 1 hour, and then 3-methylpyridine (1 mol,93.13 g) and triphenyl phosphite (0.21 mol,65.16 g) were added, and the temperature was raised to 100 to 110℃and stirred under nitrogen atmosphere for 12 hours to obtain a mixed solution. The mixed solution is poured into methanol to precipitate, and then filtered to obtain a solid, and then the solid is purified by methanol to obtain a polyamide composition solid.

Comparative example 5

Into a 500ml reaction flask were charged diamine ENPSDA (0.085 mol,37.59 g), diamine ODA (0.015 mol,3.00 g), dicarboxylic acid IPA (0.1 mol,16.61 g) and solvent NMP (171.61 g), and then dissolved by stirring under nitrogen atmosphere for 1 hour, and then 3-methylpyridine (1 mol,93.13 g) and triphenyl phosphite (0.21 mol,65.16 g) were added, and the temperature was raised to 100 to 110℃and stirred under nitrogen atmosphere for 12 hours to obtain a mixed solution. The mixed solution is poured into methanol to precipitate, and then filtered to obtain a solid, and then the solid is purified by methanol to obtain a polyamide composition solid.

The polyamide composition solids (20 g) obtained in examples 1 to 8 and comparative examples 2 to 5 and 0.004g of the catalyst were dissolved in a solvent NMP (80 g) by stirring for 12 hours in a 250ml reaction flask under an air atmosphere at normal temperature, to obtain a polyamide solution having a solid content of 15 to 20%. The viscosity of the polyamide solution is 10-20 ten thousand cps. The polyamide solution is coated on a steel plate and baked for 20-30 min at 120 ℃ to obtain a film with the solvent content of 25-30%. And then peeling the film from the steel plate, stretching the film at the temperature of 130 ℃ for 100-150%, keeping the temperature at 150 ℃ for 30min to remove the solvent, heating to 400-450 ℃ at 2.5 ℃/min and keeping the temperature for 1 hour for annealing treatment, and finally cooling to room temperature at 5-8 ℃/min to obtain the polyamide film.

The polyamic acid solution prepared in comparative example 1 was coated on a steel sheet, and baked at 120℃for 20 to 30 minutes to obtain a film having a solvent content of 25 to 30%. And then peeling the film from the steel plate, stretching the film at 130 ℃ for 100-150%, heating to 300-370 ℃ at 2.5 ℃/min under nitrogen environment, maintaining the temperature for 1 hour for cyclization treatment, heating to 400-450 ℃ at 2.5 ℃/min, maintaining the temperature for 1 hour for annealing treatment, and finally cooling to room temperature at 5-8 ℃/min to obtain the polyamide film.

The polyamide films prepared in examples 1 to 8 and comparative examples 1 to 5 were placed between two graphite plates, respectively, and heated from room temperature to 950 to 1050 ℃ at a rate of 2 to 3 ℃/min under an inert gas (argon) atmosphere, and cooled to room temperature at a rate of 15 to 20 ℃/min after being kept at a constant temperature for 60 minutes, to obtain carbonized films.

The carbonized films prepared in examples 1 to 8 and comparative examples 1 to 5 were placed between two graphite plates, respectively, and heated from room temperature to 2800 to 2900 ℃ at a rate of 2 to 3 ℃/min under an inert gas (argon) atmosphere, and then cooled to room temperature at a rate of 15 to 20 ℃/min after constant temperature for 40min, and the graphitized film was rolled (10 MPa) to obtain a graphite film.

The partial packet contents of examples 1 to 8 and comparative examples 1 to 5 are shown in Table 1.

The polyamide films prepared in examples 1-8 and comparative examples 1-5 were tested for thickness and subjected to thermogravimetric analysis (TGA). The thermogravimetric analysis conditions were: the nitrogen environment and the temperature range are 40-800 ℃ and the temperature rising rate is 10 ℃/min. Wherein the temperature at which the weight is reduced to 5% is Td5%, and the remaining weight at 800 ℃ is the coke residual rate. The graphite films prepared in examples 1 to 8 and comparative examples 1 to 5 were tested for thickness, density, and thermal conductivity. The test results are shown in Table 2.

TABLE 1

TABLE 2

In comparison with comparative example 1, the polyamides of examples 1 to 8 are prepared from diamine monomers including ENPSDA, which can produce polyamide solutions, and the polyamide films produced have a high carbon content (coke residual ratio of more than 70%). The graphite films of examples 1-8 produced with polyamide films of the same thickness had good appearance and similar density (about 2.0g/cm ³ ) The method comprises the steps of carrying out a first treatment on the surface of the And the prepared polyamide film has thicker thickness and higher heat conductivity coefficient. This is because polyamide films made from diamine monomers including ENPSDA have a higher carbon content and a lower defect content after graphitization. In comparative example 1, however, the biaxially stretching was carried out in the state of a polyamic acid film because the polyamide solution could not be produced, but the intramolecular structure was changed (condensation ring closure and molecular polarity were lowered) and gas was dissipated (dehydration cyclization) during cyclization at high temperature, so that the thick intermolecular arrangement structure was destroyed (defect amount was increased) during biaxial stretching, and further the graphite film density was 2.0g/cm ³ But with a lower thermal conductivity (< 1650W/m K).

As is clear from examples 1 to 8 and comparative examples 2 to 5, the ENPSDA in the diamine monomer is required to be 90mol% or more to give a polyamide film having a high carbon content (char residue ratio of more than 70%); less than 90mol%, the polyamide film has a char residue of less than 70%, and the resulting graphite has reduced thickness, increased defect levels, and reduced thermal conductivity (less than 1650W/m x K). It is presumed that the ENPSDA unit monomer has 5 benzene rings and bonds with nitrogen (N) between benzene rings (heat resistance is preferable), the ODA unit monomer has 2 benzene rings and bonds with oxygen (O) between benzene rings (heat resistance is poor, for example, oxygen (O) in carbonization process ₂ ) Will escape first). Comparative examples 2 to 5 (ENPSDA at 85% in diamine monomer) compared to examples 2, 4, 6 and 8 (ENPSDA at 90% in diamine monomer)) The number of benzene rings of diamine monomer is reduced, and the number of benzene rings bonded by N is reduced, so that the heat resistance of the prepared polyimide film is reduced (the residual rate of coke is reduced) in a TGA test, and the polyimide film is carbonized, graphitized and excessively pressed to be thick, the thickness is reduced to a larger extent, although the density is about 2.0g/cm ³ However, the number of O bonds between benzene rings is relatively increased, and thus the overall arrangement structure is destroyed (the defect amount is increased), and the thermal conductivity is lowered.

The foregoing disclosure is merely illustrative of the presently preferred embodiments of the present application and, of course, is not intended to limit the invention thereto, but to cover modifications as fall within the scope of the present application.

Claims

1. A graphite film is characterized in that the graphite film is prepared by carbonizing and graphitizing a polyamide film; the polyamide membrane comprises a polyamide polymer; the polyamide polymer comprises the reaction product of a diamine monomer and a dicarboxylic acid monomer, the diamine monomer being 90 mole% ENPSDA and 10 mole% diaminodiphenyl ether; the structure of the ENPSDA is

；

The dicarboxylic acid monomer includes at least one of 2, 6-naphthalene dicarboxylic acid, 4 '-diphenyl ether dicarboxylic acid, biphenyl dicarboxylic acid, 1, 4-phthalic acid, 1, 3-phthalic acid, and 4,4' -sulfonyl dibenzoic acid.