High-performance polyimide film and preparation method thereof

Abstract

The invention discloses a high-performance polyimide film and a preparation method thereof, and belongs to the technical field of polyimide. The preparation method comprises the following steps: calcining boron nitride for surface oxidation, dispersing in ionized water, and carrying out ultrasonic treatment, centrifugation and drying to obtain micro-nitric boron nitride; the preparation method comprises the following steps: dispersing micro-nitric boron nitride in deionized water, and adding polyethyleneimine for reaction to obtain modified boron nitride; respectively dispersing a diamine monomer and the modified boron nitride in an organic solvent to respectively obtain a diamine solution and a dispersion liquid; adding the dispersion liquid into a diamine solution, then adding a dianhydride monomer and an end-capping reagent to obtain polyamic acid, carrying out defoaming treatment, then coating the polyamic acid to form a film, and carrying out imidization treatment to obtain a polyimide film; polyethyleneimine is adsorbed on the surface of BN, so that agglomeration of BN in a PI matrix can be inhibited, the dispersity and compatibility of BN in the PI matrix are improved, movement of molecular chains is better inhibited, meanwhile, generated heat is led out, the thermal stability of the PI film is improved, and the thermal expansion coefficient is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of polyimide, and in particular relates to a high-performance polyimide film and a preparation method thereof. Background Art

[0002] Polyimide (PI) refers to a class of polymers containing an imide ring (-CO-N-CO-) in the main chain. Due to its excellent electrical insulation, thermal stability, radiation resistance, mechanical properties and low dielectric properties, it is widely used in aerospace, electrical insulation, flexible circuit boards, flexible displays, microelectronics and many other fields.

[0003] In recent years, with the rapid development of electronic devices, especially in the field of COF packaging and organic electroluminescent device (OLED) manufacturing, higher requirements have been put forward for polyimide film materials as substrates: first, ultra-high strength is required to support and insulate semiconductor chips; second, it needs to have good dimensional stability and a similar thermal expansion coefficient (CTE) to semiconductor materials or glass substrates to prevent bending, shedding and interface stress of the substrate due to mismatch of thermal expansion coefficients, thereby affecting device stability and operational safety; third, it needs to have extremely high heat resistance stability to avoid contamination of devices by small molecules produced by thermal decomposition during high-temperature processing, affecting product yield. However, the performance of traditional polyimide films can no longer meet the use requirements, which greatly limits the wider application of polyimide films. Therefore, it is very necessary to develop a high-performance polyimide film.

[0004] Boron nitride not only has good thermal conductivity, but can also reduce the thermal expansion coefficient of polymers and improve the thermal stability of polymers. However, its surface is relatively inert, making it difficult to be compatible with polymers and prone to agglomeration, which limits the application of boron nitride. In addition, single boron nitride does not have a very obvious effect on improving polymer performance. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a high-performance polyimide film and a preparation method thereof, which solves the problems in the prior art.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing a polyimide film comprises the following steps:

[0008] The boron nitride is calcined for surface oxidation, dispersed in ionized water, and subjected to ultrasonication, centrifugation, and drying to obtain micro-oxidized boron nitride;

[0009] Dispersing micro-oxidized boron nitride in deionized water, adding polyethyleneimine, stirring, and centrifugally drying to obtain modified boron nitride;

[0010] Dispersing the diamine monomer and the modified boron nitride in an organic solvent to obtain a diamine solution and a dispersion, respectively;

[0011] The dispersion is added to the diamine solution, and then the dianhydride monomer and the end-capping agent are added to obtain polyamic acid, and a defoaming treatment is performed;

[0012] The defoamed polyamic acid is coated to form a film, and then subjected to imidization treatment to obtain a polyimide film.

[0013] Furthermore, the calcination temperature is 800° C. and the calcination time is 2 h.

[0014] Furthermore, the organic solvent is one of N,N-dimethylacetamide, N,N-dimethylformamide and N-methylpyrrolidone.

[0015] Furthermore, the diamine monomer is one or two of p-phenylenediamine, 4,4'-diaminodiphenyl ether, and 4,4'-diaminobenzanilide.

[0016] Furthermore, the dianhydride monomer is one or two of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 4,4'-biphenyl ether dianhydride.

[0017] Furthermore, the end-capping agent is one of 1,2,4-benzenetricarboxylic anhydride or phthalic anhydride.

[0018] Furthermore, the mass ratio of the modified boron nitride to the diamine monomer is (0.074-0.191):1; the molar ratio of the diamine monomer to the dianhydride monomer is 1:(0.98-1), and the end-capping agent is 4% of the molar fraction of the diamine.

[0019] Furthermore, the imidization process is: keeping warm at 110°C for 30 minutes, keeping warm at 210°C for 40 minutes, keeping warm at 260°C for 40 minutes, keeping warm at 310°C for 40 minutes, and keeping warm at 360°C for 40 minutes.

[0020] A polyimide film is prepared using the above-mentioned method for preparing a polyimide film.

[0021] Furthermore, the thickness of the polyimide film is 25-50 um.

[0022] The above-mentioned polyimide film is used in the preparation of semiconductor devices.

[0023] Beneficial effects of the present invention:

[0024] 1. In the present invention, highly cationic polyethyleneimine is adsorbed onto the surface of high-temperature calcined micro-oxidized negatively charged boron nitride by an electrostatic self-assembly method to obtain a P-BN modified filler; P-BN and a polymerization monomer and a capping agent of polyimide are subjected to an in-situ polymerization reaction in a solvent to obtain polyamic acid, and finally a polyimide film is obtained by film casting and heat treatment; polyethyleneimine adsorbed on the BN surface can inhibit the agglomeration of BN in the PI matrix, improve the dispersibility and compatibility of BN in the PI matrix, better inhibit the movement of the molecular chain, and at the same time conduct the generated heat, thereby improving the thermal stability of the PI film and reducing the thermal expansion coefficient.

[0025] 2. The introduction of active carboxyl end-capping agent in the present invention can further improve the thermal stability of PI film and reduce the thermal expansion coefficient.

[0026] 3. The PI film prepared by the present invention has a low thermal expansion coefficient, good thermal stability, good mechanical properties, and a simple preparation process, and has a good value for promotion and use. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The technical solution of the present invention is described in detail below by specific implementation; the raw materials used in the embodiments and comparative examples are as follows:

[0029] Boron nitride is hexagonal boron nitride with a particle size of 0.2-1 μm, purchased from 3M China Co., Ltd.

[0030] Polyethyleneimine (PEI) was purchased from Xi'an Qiyue Biological Co., Ltd.;

[0031] PDA (p-phenylenediamine) was purchased from Dingyuan Shangshi New Materials Co., Ltd.;

[0032] PMDA (pyromellitic dianhydride) was purchased from Nanjing Lonza Co., Ltd.;

[0033] BPDA (3,3′,4,4′-biphenyltetracarboxylic dianhydride) was purchased from Tianjin Zotye Materials Technology Co., Ltd.;

[0034] TMA (1,2,4-benzenetricarboxylic anhydride) was purchased from Hubei Hengjingrui Chemical Co., Ltd.;

[0035] DMAC (N,N-dimethylacetamide) was purchased from Anyang Jiutian Chemical Group.

[0036] Example 1

[0037] A method for preparing a high-performance polyimide film comprises the following steps:

[0038] 1) Preparation of micro-oxidized boron nitride: 10 g of boron nitride powder was weighed and placed in an air atmosphere muffle furnace, calcined at 800° C. for 2 hours for surface micro-oxidation, and then ionized water was added, and then centrifuged and dried after ultrasonication to prepare micro-oxidized boron nitride;

[0039] 2) Preparation of modified boron nitride: 8 g of micro-oxidized boron nitride was first dispersed in 80 ml of deionized water, and then 0.6 g of polyethyleneimine (PEI) was added and stirred for 2 hours; after centrifugation and drying, modified boron nitride (P-BN) was obtained;

[0040] 3) 4.325 g of PDA (p-phenylenediamine) was added to 66 g of DMAC (N, N-dimethylacetamide) to dissolve to obtain a diamine solution, and 0.321 g of P-BN was dispersed in 6 g of DMAC and dispersed in a disperser for 2 hours to obtain a dispersion;

[0041] 4) adding the dispersion prepared in step 3) to the diamine solution to react for 1 hour, then adding 10.3 g BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride) and 1.09 g PMDA (pyromellitic dianhydride) to the above solution in 4 portions, and when the system viscosity reaches 130,000 mPa·s, a polyamic acid containing P-BN is obtained, and vacuum defoaming treatment is performed in a -0.1 Mpa oven;

[0042] 5) The defoamed polyamic acid is coated on a glass plate of an automatic coating machine to form a film with a thickness of 38 μm, and then imidization is performed. The imidization process is as follows: heat preservation at 110°C for 30 min, 210°C for 40 min, 260°C for 40 min, 310°C for 40 min, and 360°C for 40 min, and then cooled to obtain a PI film containing P-BN.

[0043] Example 2

[0044] The preparation method of P-BN in this embodiment is the same as that in embodiment 1, that is, steps 1) and 2), except that:

[0045] 3) 4.325 g of PDA (p-phenylenediamine) was added to 66 g of DMAC to dissolve to obtain a diamine solution, and 0.827 g of P-BN was dispersed in 6 g of DMAC and dispersed in a disperser for 2 hours to obtain a dispersion;

[0046] 4) adding the dispersion prepared in step 3) to the diamine solution to react for 1 hour, then adding 10.3 g BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride) and 1.09 g PMDA (pyromellitic dianhydride) to the above solution in 4 portions, and when the system viscosity reaches 130,000 mPa·s, a polyamic acid containing P-BN is obtained, and vacuum defoaming treatment is performed in a -0.1 Mpa oven;

[0047] 5) The defoamed polyamic acid is coated on a glass plate of an automatic coating machine to form a film with a thickness of 38 μm, and then imidization is performed. The imidization process is as follows: heat preservation at 110°C for 30 min, 210°C for 40 min, 260°C for 40 min, 310°C for 40 min, and 360°C for 40 min, and then cooled to obtain a PI film containing P-BN.

[0048] Example 3

[0049] The preparation method of P-BN in this embodiment is the same as that in embodiment 1, that is, steps 1) and 2), except that:

[0050] 3) 4.325 g of PDA (p-phenylenediamine) was added to 66 g of DMAC to dissolve to obtain a diamine solution, and 0.827 g of P-BN was dispersed in 6 g of DMAC and dispersed in a disperser for 2 hours to obtain a dispersion;

[0051] 4) adding the dispersion prepared in 3) to the diamine solution to react for 1 hour, then adding 10.3 g BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride) and 0.925 g PMDA (pyromellitic dianhydride) to the above solution in 4 portions, and finally adding 0.31 g TMA (1,2,4-benzenetricarboxylic anhydride), and when the system viscosity reaches 130,000 mPa·s, a polyamic acid containing P-BN and a capping agent is obtained, and vacuum defoaming treatment is performed in a -0.1 MPa oven;

[0052] 5) The defoamed polyamic acid is coated on a glass plate of an automatic coating machine to form a film with a thickness of 38 μm, and then imidization is performed. The imidization process is as follows: heat preservation at 110°C for 30 min, 210°C for 40 min, 260°C for 40 min, 310°C for 40 min, and 360°C for 40 min, and then cooled to obtain a PI film containing P-BN.

[0053] In some other embodiments, the thickness of the prepared PI film is 25-50 um.

[0054] The organic solvent in step 2) can be one of: N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

[0055] In step 3), the diamine monomer may be one or two of p-phenylenediamine, 4,4'-diaminodiphenyl ether, and 4,4'-diaminobenzanilide.

[0056] In step 4), the dianhydride monomer is one or two of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 4,4'-biphenyl ether dianhydride; and the end-capping agent is one of 1,2,4-benzenetricarboxylic anhydride or phthalic anhydride.

[0057] Comparative Example 1

[0058] A method for preparing a polyimide film comprises the following steps:

[0059] 1) 4.325 g of PDA (p-phenylenediamine) was added to 66 g of DMAC to dissolve, and 0.321 g of BN was dispersed in 6 g of DMAC, and dispersed in a disperser for 2 hours to obtain a dispersion;

[0060] 2) adding the dispersion prepared in 1) to the diamine solution to react for 1 hour, then adding 10.3 g BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride) and 1.09 g PMDA (pyromellitic dianhydride) to the above solution in 4 portions, and when the system viscosity reaches 130,000 mPa·s, a polyamic acid containing BN is obtained, and vacuum defoaming treatment is performed in a -0.1 Mpa oven;

[0061] 5) The defoamed polyamic acid is coated on a glass plate of an automatic coating machine to form a film with a thickness of 38 μm, and then imidization is performed. The imidization process is as follows: heat preservation at 110°C for 30 min, 210°C for 40 min, 260°C for 40 min, 310°C for 40 min, and 360°C for 40 min, and then cooled to obtain a PI film containing BN.

[0062] Comparative Example 2

[0063] A method for preparing a polyimide film comprises the following steps:

[0064] 1) 4.325 g of PDA (p-phenylenediamine) was added to 66 g of DMAC to dissolve, and 0.827 g of BN was dispersed in 6 g of DMAC, and dispersed in a disperser for 2 hours to obtain a dispersion;

[0065] 2) adding the dispersion prepared in 1) to the diamine solution to react for 1 hour, then adding 10.3 g BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride) and 1.09 g PMDA (pyromellitic dianhydride) to the above solution in 4 portions, and when the system viscosity reaches 130,000 mPa·s, a polyamic acid containing BN is obtained, and vacuum defoaming treatment is performed in a -0.1 Mpa oven;

[0066] 3) The defoamed polyamic acid is coated on a glass plate of an automatic coating machine to form a film with a thickness of 38 μm, and then imidization is performed. The imidization process is as follows: heat preservation at 110° C. for 30 min, 210° C. for 40 min, 260° C. for 40 min, 310° C. for 40 min, and 360° C. for 40 min, and then cooled to obtain a PI film containing BN.

[0067] Comparative Example 3

[0068] A method for preparing a polyimide film comprises the following steps:

[0069] 1) Add 4.325 g PDA (p-phenylenediamine) to 72 g DMAC and dissolve;

[0070] 2) 10.3 g BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride) and 1.09 g PMDA (pyromellitic dianhydride) were added to the above solution in 4 portions, and when the viscosity of the system reached 130,000 mPa·s, polyamic acid was obtained, and vacuum defoaming treatment was carried out in a -0.1 MPa oven;

[0071] 3) The defoamed polyamic acid is coated on a glass plate of an automatic coating machine to form a film with a thickness of 38 μm, and then imidized. The imidization process is as follows: heat preservation at 110° C. for 30 min, 210° C. for 40 min, 260° C. for 40 min, 310° C. for 40 min, and 360° C. for 40 min, and then cooled to obtain a PI film.

[0072] Experimental verification:

[0073] The thermal expansion coefficient, thermal decomposition temperature and mechanical properties of the polyimide films prepared in Examples 1-3 and Comparative Examples 1-3 were tested. The results are shown in Table 1.

[0074] Among them, the thermal expansion coefficient test: GB / T36800.2 standard is used for testing;

[0075] Thermal decomposition temperature test: GB / T33047.1 standard is used for testing;

[0076] Mechanical properties test: Tested according to GB / T 1040.3-2006 standard.

[0077] Table 1 Thermal expansion coefficient, thermal decomposition and mechanical properties of polyimide films

[0078]

[0079] As can be seen from Table 1, compared with Comparative Example 3, the thermal expansion coefficients of Examples 1-3 and Comparative Example 1-2, which were added with BN, decreased to varying degrees, and the thermal decomposition temperature T 5％ All of them have been improved to varying degrees, but compared with Comparative Examples 1-2, the effect of Example 1-3 is more obvious. This is due to the fact that the adsorption of polyethyleneimine on the BN surface can inhibit the agglomeration of BN in the PI matrix, improve the dispersibility and compatibility of BN in the PI matrix, better inhibit the movement of the molecular chain, and at the same time export the generated heat, thereby reducing the thermal expansion coefficient of the PI film and improving the thermal stability; on the other hand, the introduction of active carboxyl end-capping agents can further reduce the thermal expansion coefficient of the PI film and improve the thermal stability. Compared with Comparative Example 3, the tensile strength of Examples 1-3 and Comparative Example 1-2 has decreased, but the amplitude of Example 1-3 is smaller, which is mainly due to the rich amino groups on the P-BN surface, which has better compatibility with the PI film.

[0080] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0081] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A method for preparing a polyimide film, characterized in that: The following steps are involved: The boron nitride is calcined for surface oxidation, dispersed in ionized water, and subjected to ultrasonication, centrifugation, and drying to obtain micro-oxidized boron nitride; Dispersing micro-oxidized boron nitride in deionized water, adding polyethyleneimine, stirring, and centrifugally drying to obtain modified boron nitride; Dispersing the diamine monomer and the modified boron nitride in an organic solvent to obtain a diamine solution and a dispersion, respectively; The dispersion is added to the diamine solution, and then the dianhydride monomer and the end-capping agent are added to obtain polyamic acid, and a defoaming treatment is performed; The defoamed polyamic acid is coated to form a film, and then subjected to imidization treatment to obtain a polyimide film.

2. The method for preparing a polyimide film according to claim 1, characterized in that: The calcination temperature is 800° C. and the calcination time is 2 h.

3. The method for preparing a polyimide film according to claim 1, characterized in that: The organic solvent is one of N,N-dimethylacetamide, N,N-dimethylformamide and N-methylpyrrolidone.

4. The method for preparing a polyimide film according to claim 1, characterized in that: The diamine monomer is one or two of p-phenylenediamine, 4,4'-diaminodiphenyl ether and 4,4'-diaminobenzanilide.

5. The method for preparing a polyimide film according to claim 1, characterized in that: The dianhydride monomer is one or two of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride and 4,4'-biphenyl ether dianhydride.

6. The method for preparing a polyimide film according to claim 1, characterized in that: The end-capping agent is one of 1,2,4-benzenetricarboxylic anhydride and phthalic anhydride.

7. The method for preparing a polyimide film according to claim 1, characterized in that: The mass ratio of the modified boron nitride to the diamine monomer is (0.074-0.191):1; the molar ratio of the diamine monomer to the dianhydride monomer is 1:(0.98-1), and the end-capping agent is 4% of the molar fraction of the diamine.

8. The method for preparing a polyimide film according to claim 1, characterized in that: The imidization process is: heat preservation at 110° C. for 30 minutes, heat preservation at 210° C. for 40 minutes, heat preservation at 260° C. for 40 minutes, heat preservation at 310° C. for 40 minutes, and heat preservation at 360° C. for 40 minutes in sequence.

9. A polyimide film, characterized in that: The polyimide film is prepared by the method for preparing the polyimide film according to any one of claims 1 to 8.

10. The polyimide film according to claim 1, characterized in that: The thickness of the polyimide film is 25-50 um.

11. Use of the polyimide film according to claim 9 or 10 in preparing semiconductor devices.

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