CN115894989A - Preparation method of polyimide film, polyimide film and application of polyimide film - Google Patents
Preparation method of polyimide film, polyimide film and application of polyimide film Download PDFInfo
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- 238000002360 preparation method Methods 0.000 title claims abstract description 12
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- 150000004985 diamines Chemical class 0.000 claims abstract description 38
- GTDPSWPPOUPBNX-UHFFFAOYSA-N ac1mqpva Chemical compound CC12C(=O)OC(=O)C1(C)C1(C)C2(C)C(=O)OC1=O GTDPSWPPOUPBNX-UHFFFAOYSA-N 0.000 claims abstract description 37
- 238000000034 method Methods 0.000 claims abstract description 37
- 229920005575 poly(amic acid) Polymers 0.000 claims abstract description 31
- 239000000919 ceramic Substances 0.000 claims abstract description 27
- 230000008569 process Effects 0.000 claims abstract description 14
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 13
- 238000004132 cross linking Methods 0.000 claims abstract description 12
- 239000002904 solvent Substances 0.000 claims abstract description 9
- 239000002798 polar solvent Substances 0.000 claims abstract description 7
- 238000003756 stirring Methods 0.000 claims abstract description 5
- 238000004528 spin coating Methods 0.000 claims description 17
- 239000007787 solid Substances 0.000 claims description 15
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 13
- 238000010438 heat treatment Methods 0.000 claims description 13
- 239000011261 inert gas Substances 0.000 claims description 13
- VLDPXPPHXDGHEW-UHFFFAOYSA-N 1-chloro-2-dichlorophosphoryloxybenzene Chemical compound ClC1=CC=CC=C1OP(Cl)(Cl)=O VLDPXPPHXDGHEW-UHFFFAOYSA-N 0.000 claims description 12
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 12
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 11
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 claims description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 10
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 6
- JVERADGGGBYHNP-UHFFFAOYSA-N 5-phenylbenzene-1,2,3,4-tetracarboxylic acid Chemical compound OC(=O)C1=C(C(O)=O)C(C(=O)O)=CC(C=2C=CC=CC=2)=C1C(O)=O JVERADGGGBYHNP-UHFFFAOYSA-N 0.000 claims description 5
- -1 hexafluoro dianhydride Chemical compound 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- 230000035484 reaction time Effects 0.000 claims description 5
- 230000003746 surface roughness Effects 0.000 claims description 5
- 229940018564 m-phenylenediamine Drugs 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- HLBLWEWZXPIGSM-UHFFFAOYSA-N 4-Aminophenyl ether Chemical compound C1=CC(N)=CC=C1OC1=CC=C(N)C=C1 HLBLWEWZXPIGSM-UHFFFAOYSA-N 0.000 claims description 3
- LACZRKUWKHQVKS-UHFFFAOYSA-N 4-[4-[4-amino-2-(trifluoromethyl)phenoxy]phenoxy]-3-(trifluoromethyl)aniline Chemical compound FC(F)(F)C1=CC(N)=CC=C1OC(C=C1)=CC=C1OC1=CC=C(N)C=C1C(F)(F)F LACZRKUWKHQVKS-UHFFFAOYSA-N 0.000 claims description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 3
- 229910052786 argon Inorganic materials 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 239000001307 helium Substances 0.000 claims description 3
- 229910052734 helium Inorganic materials 0.000 claims description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 3
- 239000011521 glass Substances 0.000 abstract description 11
- 238000004377 microelectronic Methods 0.000 abstract description 4
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- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical group [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 7
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- 238000009835 boiling Methods 0.000 description 6
- 239000004642 Polyimide Substances 0.000 description 5
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 239000006087 Silane Coupling Agent Substances 0.000 description 4
- 229910021389 graphene Inorganic materials 0.000 description 4
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- 238000006068 polycondensation reaction Methods 0.000 description 3
- 239000004952 Polyamide Substances 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 238000004220 aggregation Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
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- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
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- 125000004427 diamine group Chemical group 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/549—Organic PV cells
Abstract
The invention provides a preparation method of a polyimide film, the polyimide film and application thereof. The preparation method of the polyimide film is used for solving the problem that the existing ultrathin polyimide film is difficult to rapidly demold, and comprises the following steps: adding diamine into a polar solvent and stirring to completely dissolve the diamine; adding dianhydride into the solution for multiple times, stirring to completely dissolve the dianhydride and performing crosslinking polymerization to generate polyamic acid; and coating the polyamic acid solution on a polished ceramic substrate, prebaking to remove the solvent, and carrying out high-temperature imidization to obtain the polyimide film. The demolding process replaces the traditional glass substrate with the polished ceramic substrate, and the polyimide film is rapidly stripped. The polyimide film has high surface smoothness, high temperature resistance and excellent mechanical property, and can be applied to the fields of flexible circuit boards, microelectronic packaging and the like, thereby having wide application prospects.
Description
Technical Field
The invention relates to the technical field of electronic materials, in particular to a preparation method of a polyimide film, the polyimide film and application thereof.
Background
With the rapid development of high-end integrated circuit technology, urgent requirements for high temperature resistance and excellent mechanical properties are provided for large-size flexible Organic Light Emitting Diodes (OLEDs). The manufacture of flexible substrates in flexible display devices is crucial to the quality assurance of flexible displays, and demands for high temperature resistance and transparency are placed on flexible substrate materials. The polyimide film has excellent high temperature resistance, moisture resistance, mechanical properties and good chemical stability, and is widely applied as a flexible substrate material in the field of flexible electronics.
The flexible substrate material is limited to low rigidity, and the flexible substrate material is usually coated on a rigid substrate and separated from the rigid substrate to realize the manufacturing of the flexible display device, so how to realize the simple peeling of the flexible substrate material and the substrate is an extremely important process step in the field of flexible electronics.
At present, the peeling methods of the flexible substrate material and the substrate include laser peeling, physical peeling and chemical peeling. The laser stripping mainly adopts the technology of separating and stripping the substrate and the flexible substrate by laser energy, has short stripping time, small influence area, but higher cost, and the strong laser energy can damage a film with certain thickness, so that the universality is low. The chemical stripping method etches the substrate based on the chemical corrosive liquid, has certain damage to stripping, has longer stripping period and is difficult to be applied to large-scale stripping. The physical peeling method generally uses optical glass as a substrate, and peeling between the flexible film and the glass substrate is easily achieved by a boiling method. However, the bonding force between the silane coupling agent in the flexible film material and the glass substrate is strong, and the conventional boiling method is difficult to realize the peeling of the film with the silane coupling agent on the glass substrate. Therefore, it is of great significance to find a highly efficient and universal method for preparing polyimide films.
In chinese patent publication No. CN 110867533A, the inventors used graphene as a sacrificial layer, and promoted liquid permeation and diffusion by using ultrasonic waves, thereby breaking van der waals force between graphene film layers and realizing that a polyimide film is peeled off from a film substrate. When the graphene sacrificial layer is thick (about 120 nm), the polyimide film can have a light black graphene color, and the light transmittance of the polyimide is affected finally.
In chinese patent No. CN112018033B, the inventor epitaxially grows an undoped GaN layer, a heavily doped GaN sacrificial layer, and a target layer in sequence on a substrate to form an epitaxial layer, places the epitaxial layer in a flowing electrolyte at a certain inclination angle, and electrochemically corrodes the heavily doped GaN sacrificial layer to finally obtain the target layer. Although the method can realize the peeling of the target layer on the substrate, the operation is complex, the cost is high, and the large-area peeling preparation has great limitations.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a preparation method of a polyimide film, the polyimide film and application thereof.
In order to achieve the above object, according to a first aspect of the present invention, there is provided a method for preparing a polyimide film, comprising the steps of:
(S1) uniformly stirring diamine and a polar solvent in inert gas to obtain a completely dissolved diamine solution;
(S2) adding dianhydride into the uniformly mixed diamine solution for multiple times, and performing cross-linking polymerization in inert gas to generate a polyamic acid solution;
and (S3) spin-coating the polyamic acid solution on the polished surface of the ceramic substrate, pre-drying to remove the solvent, and performing thermal imidization to obtain the polyimide film.
Further, the diamine is selected from one or more of metaphenylene diamine (MPD), 1, 4-bis (4-amino-2-trifluoromethylphenoxy) benzene (6 FAPB), 4' -diaminodiphenyl ether (ODA); the dianhydride is one or more of biphenyl tetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA) and hexafluoro dianhydride (FFDA); the polar solvent is one or more of N, N-Dimethylformamide (DMF), N-Dimethylacetamide (DMAC) and N-methyl pyrrolidone (NMP).
Further, the molar ratio of the diamine to the dianhydride is 0.96 to 1.0.
Further, the temperature of the cross-linking polymerization reaction in the step (S2) is 10-50 ℃, and the reaction time is 8-12 h; the inert gas is selected from one of helium, nitrogen and argon.
Further, the flow rate of the inert gas is 30-70 mL/min.
Further, the solid content of the polyamic acid solution is 10-30%, and the viscosity is 300-3000 cp.
Further, the ceramic substrate is selected from SiC and ZrO 2 Or Al 2 O 3 One kind of (1).
Further, the surface roughness Ra of the ceramic substrate is 0.05-0.10.
Further, the spin coating process parameter of (S3) is to increase the rotation speed in a stepwise manner, and the process of increasing the rotation speed in a stepwise manner is: the first stage is spin coating at 200-300r/min for 20-30s; the second stage is that spin coating is carried out at 500-800r/min for 20-30s; the third stage is spin coating at 1000-1500r/min for 30-50s.
Further, the thermal imidization adopts step temperature programming, and the temperature rise rate is 2-5 ℃/min;
further, the step temperature programming process comprises: firstly, heating at 60-80 ℃ for 0.5-1h, raising the temperature to 140-160 ℃, and preserving the heat for 1-1.5h; then, heating to 240-260 ℃, and preserving heat for 1-1.5h; finally, the temperature is raised to 300 to 330 ℃, and the temperature is kept for 0.5 to 1 hour.
According to a second aspect of the present invention, there is provided a polyimide film prepared by the method for preparing a polyimide film according to the first aspect.
According to a third aspect of the present invention, there is provided a use of a polyimide film for a flexible display substrate.
By applying the technical scheme of the application, compared with the prior art, the application has the following beneficial effects:
(1) The traditional glass substrate is replaced by the polished compact ceramic substrate, so that the polyimide film is quickly stripped, and the polished ceramic substrate can be repeatedly used, is energy-saving and environment-friendly; meanwhile, the process is simple to operate, does not need to change the existing synthesis and processing equipment, and is easy for industrial production.
(2) According to the invention, the cured and cooled polyimide film is directly peeled off, so that the traditional glass substrate boiling peeling method is saved, the dehydration imidization of the polyimide film is inhibited, and the mechanical property of the polyimide film material is improved to a certain extent.
(3) The polyimide film has high surface smoothness, high temperature resistance and excellent mechanical property, and can be applied to the fields of flexible circuit boards, microelectronic packaging and the like, thereby having wide application prospect.
Drawings
FIG. 1 is a surface roughness topography of a polished silicon carbide ceramic substrate according to one embodiment of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Unless defined otherwise, technical or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
The polyimide film has the characteristics of excellent thermal stability, electrical insulation, mechanical property, dielectric property, good bending property and the like, and is widely applied to the fields of mobile phones, microelectronic integrated circuits, flexible printed circuit substrates, rail transit and aerospace. However, the silane coupling agent in the flexible polyimide film material has strong binding force with the glass substrate, and the conventional boiling method is difficult to realize the peeling of the film with the silane coupling agent on the glass substrate. Therefore, it is of great significance to find a preparation method of polyimide film with high efficiency and universality.
In an exemplary embodiment of the present application, there is provided a method for preparing a polyimide film, including the steps of:
(S1) uniformly stirring diamine and a polar solvent in inert gas to obtain a completely dissolved diamine solution;
(S2) adding dianhydride into the uniformly mixed diamine solution for multiple times, and performing crosslinking polymerization in inert gas to generate a polyamic acid solution;
and (S3) spin-coating the polyamic acid solution on the polished surface of the ceramic substrate, pre-drying to remove the solvent, and performing thermal imidization to obtain the polyimide film.
In a specific embodiment herein, the diamine is selected from one or more of m-phenylenediamine (MPD), 1, 4-bis (4-amino-2-trifluoromethylphenoxy) benzene (6 FAPB), 4' -diaminodiphenyl ether (ODA); the dianhydride is one or more of biphenyl tetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA) and hexafluoro dianhydride (FFDA); the polar solvent is one or more of N, N-Dimethylformamide (DMF), N-Dimethylacetamide (DMAC) and N-methyl pyrrolidone (NMP).
In a preferred embodiment of the present application, the molar ratio of diamine to dianhydride is from 0.96 to 1.0. For example, the molar ratio of diamine to dianhydride can be 0.96, 0.97, 0.98, 0.99, or 1.0. But are not limited to, the above-listed values or alternatives, other values or alternatives not listed within the above-mentioned range of values or alternatives are equally applicable. If the molar ratio of diamine to dianhydride is less than 0.96, the crosslinking polymerization reaction of diamine and dianhydride is not complete, and finally the dianhydride is excessive to cause aggregation, which finally affects the surface finish of the polyimide film. If the molar ratio of diamine to dianhydride is higher than 1.0, the diamine to dianhydride crosslinking polymerization reaction is not complete, and the diamine is excessive to cause aggregation, which may affect the surface smoothness of the polyimide film.
In a specific embodiment of the present application, the temperature of the cross-linking polymerization reaction in the step (S2) is 10 to 50 ℃, and the reaction time is 8 to 12 hours. If the reaction temperature is out of the above range, the local heating unevenness of dianhydride and diamine will not be caused, and the crosslinking polymerization reaction will not be uniform, and finally the polyimide film will have local warpage or uneven thickness. If the reaction time is less than 8 hours, the crosslinking polymerization reaction of dianhydride and diamine is incomplete, resulting in dianhydride or diamine residues, affecting the molecular weight and viscosity of the polyamic acid solution, and ultimately affecting the film-forming characteristics of the polyamic acid solution. If the reaction time is longer than 12h, the molecular weight of the polyamic acid increases, and the viscosity of the solution increases, and finally the thickness of the polyimide film is difficult to control.
In a specific embodiment of the present application, the dianhydride is added to the uniformly mixed diamine solution in multiple times in step (S2), so that the dianhydride is promoted to be completely dissolved into the diamine solution, and the reaction is a reaction with an increased exothermic entropy when the diamine and the dianhydride are initially polymerized to form the resin solution, and thus the multiple addition contributes to the polymerization reaction of the molecular chain segment, and the reaction is promoted to be carried out in a forward direction, so that the molecular chain segment is continuously increased. If the dianhydride and the diamine are added at one time, the local reaction is too fast, gel is generated, and the dianhydride and the diamine which are not completely dissolved react with each other to form a crosslinking polymer, so that the phenomena of local warping or uneven thickness of the polyimide film are finally caused.
In a specific embodiment of the present application, the inert gas is selected from one of helium, nitrogen, and argon; nitrogen is preferred.
In a preferred embodiment of the present application, the inert gas is a flow gas, and the flow rate of the inert gas is 30 to 70mL/min.
In a preferred embodiment of the present application, the polyamic acid solution has a solid content of 10 to 30%. When the solid content of the polyamic acid solution is less than 10%, it is not easy to control a thickness variation of a film when a polyimide film is formed by imidization, and if the solid content is more than 30%, it is difficult to control a thickness of a polyimide film obtained in a process of preparing a polyimide film.
The viscosity of the polyamide acid solution is 300-3000 cp. When the viscosity is more than 300cp, polyamic acid with higher molecular weight can be obtained, thereby ensuring the mechanical strength of polyimide, and when the viscosity is more than 3000cp, the fluidity is poor during coating and film forming, and a uniform and flat film is difficult to obtain.
In a specific embodiment of the present application, the ceramic substrate is selected from the group consisting of SiC and ZrO 2 Or Al 2 O 3 One kind of (1). The ceramic substrate means that a copper foil is directly bonded to alumina (Al) at a high temperature 2 O 3 ) Or a special process board on the surface (single or double side) of an aluminum nitride (AlN) ceramic substrate. The manufactured ultrathin composite substrate has excellent electrical insulation performance, high heat conduction property, excellent soft weldability and high adhesion strength, can be etched into various patterns like a PCB (printed Circuit Board), and has great current carrying capacity.
In a preferred embodiment of the present application, the ceramic substrate surface roughness Ra is 0.05 to 0.10. If the roughness Ra of the ceramic substrate is lower than 0.05, the adhesion force of the ceramic substrate and the polyimide film is difficult to realize the adhesion and preparation of the polyimide film by the common spin coating process; when the roughness Ra of the ceramic substrate is higher than 0.1, the surface of the polyimide film prepared by spin coating is uneven, and the surface flatness is poor, so that the optical performance of the film is influenced.
In a specific embodiment of the present application, the spin coating process parameter of (S3) is a step-wise increasing of the rotation speed, and the step-wise increasing of the rotation speed includes: the first stage is spin coating at 200-300r/min for 20-30s; the second stage is spin-coated for 20-30s at 500-800 r/min; the third stage is spin coating at 1000-1500r/min for 30-50s. The advantage of selectively increasing the rotational speed in a stepwise manner is that: promoting the uniform coating of the polyimide solution and ensuring the size consistency of the polyimide film.
In a specific embodiment of the present application, the thermal imidization employs a step-programmed temperature rise with a temperature rise rate of 2 ℃/min to 5 ℃/min; if the temperature rise rate is lower than 2 ℃/min, the imidization degree of the polyimide is insufficient, the mechanical property of the film is seriously influenced, and the thermal property of the film is also influenced. If the heating rate is higher than 5 ℃/min, the polyimide film may have the problem of nonuniform curing, and the local solvent of the film is quickly volatilized to generate defects such as bubbles, and the quality of the polyimide film is influenced.
In a specific embodiment of the present application, the step temperature programming process is: firstly, heating at 60-80 ℃ for 0.5-1h, heating to 140-160 ℃, and preserving heat for 1-1.5h; then, heating to 240-260 ℃, and preserving heat for 1-1.5h; finally, the temperature is raised to 300-330 ℃ and the temperature is kept for 0.5-1h. The advantage of adopting the ladder procedure to heat up: the defects of cracking and the like caused by uneven curing possibly occurring in conventional temperature programming are avoided by the step temperature programming; meanwhile, the stepped temperature programming can ensure the polyimide to be completely imidized, improve the mechanical property and the optical property of the polyimide film, better improve the peel strength of the polyimide film, help to improve the dielectric property of the polyimide film and reduce the water absorption rate.
According to a second aspect of the present invention, there is provided a polyimide film prepared by the method for preparing a polyimide film according to the first aspect.
According to a third aspect of the present invention, there is provided a use of a polyimide film for a flexible display substrate.
The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the present application as claimed.
Example 1
The preparation method of the polyimide film comprises the following steps:
under nitrogen protection, 3.75g of 4,4' -diaminodiphenyl ether (ODA) and 44.82g of 1-methyl-2-pyrrolidone (NMP) were added to a three-necked flask, and ODA diamine was completely dissolved in the NMP solvent by mechanical stirring; 4.16g of pyromellitic dianhydride (PMDA) was added in portions, and mechanically stirred at 25 ℃ for 10 hours, whereby the polycondensation reaction of diamine and dianhydride completed to form a polyamic acid solution (PAA). Wherein the solid content of the polyamide acid solution is 15 percent, and the viscosity is 3000cp. And (2) carrying out vacuum defoaming treatment on the prepared polyamic acid solution, then preparing a polyamic acid wet film by using a polished silicon carbide ceramic wafer (with the surface roughness Ra 0.1 as a substrate and adopting a step-type spin coating process of 200r/min, 20s → 500r/min, 20s → 1000r/min and 30s, finally, preserving heat for 0.5h at 60 ℃ under the condition of the heating rate of 2 ℃/min, heating to 150 ℃ for 1h, heating to 250 ℃ for 1h, heating to 300 ℃ for 0.5h, and carrying out step-type imidization to realize the preparation of the polyimide film.
Example 2
The polyamic acid solution of example 2 had a solid content of 15% and a viscosity of 1200cp as in example 1, which was different from that of example 1.
Example 3
The polyamic acid solution of example 3 had a solid content of 20% and a viscosity of 3000cp as in example 1, which was different from that of example 1.
Example 4
The polyamic acid solution described in example 4 had a solid content of 15% and a viscosity of 1500cp, which are the same as those in example 1, except that the amount of the polyamic acid solution used in example 1 was changed.
Example 5
The polyamic acid solution described in example 5 had a solid content of 10% and a viscosity of 300cp, which was the same as that of example 1, except that the solution was used in example 1.
Example 6
The polyamic acid solution described in example 6 had a solid content of 30% and a viscosity of 3000cp, which was the same as that of example 1, except that the content was changed to example 1.
Example 7
Unlike example 1, example 7 added 3.75g of 4,4' -diaminodiphenyl ether (ODA) and 44.37g of 1-methyl 2-pyrrolidone (NMP) to a three-necked flask, and the ODA diamine was completely dissolved in the NMP solvent by mechanical stirring; 4.08g of pyromellitic dianhydride (PMDA) was added in divided portions, and the rest was the same as in example 1.
Example 8
Unlike example 1, example 8 added 3.75g of m-phenylenediamine (MPD) and 80.24g of N, N-Dimethylacetamide (DMAC) to a three-necked flask and the MPD diamine was completely dissolved in NMP solvent by mechanical stirring; 10.41g of biphenyltetracarboxylic dianhydride (BPDA) was added in portions and mechanically stirred at 25 ℃ for 10 hours, and the polycondensation reaction of diamine and dianhydride was completed to form a polyamic acid solution (PAA). Wherein the solid content of the polyamic acid solution is 15 percent, and the viscosity is 3000cp. The rest is the same as in example 1. .
Example 9
Unlike example 1, example 9 added 3.75g of metaphenylene diamine (MPD) and 127.44g of N, N-Dimethylacetamide (DMAC) to a three-necked flask and the MPD diamine was completely dissolved in the DMAC solvent by mechanical stirring; 10.41g of biphenyltetracarboxylic dianhydride (BPDA) was added in portions and mechanically stirred at 25 ℃ for 10 hours, and the polycondensation reaction of diamine and dianhydride was completed to form a polyamic acid solution (PAA). Wherein the solid content of the polyamic acid solution is 10 percent, and the viscosity is 2000cp. The rest is the same as in example 1. .
Example 10
The difference from example 1 is that the ceramic substrate in example 10 is zirconia, and the other points are the same as example 1.
Example 11
The difference from example 1 is that the ceramic substrate in example 11 is alumina, and the other steps are the same as example 1.
Example 12
The silicon carbide ceramic substrate of example 12 had a roughness of 0.05, which is different from example 1, and was otherwise the same as example 1.
Example 13
The thermal imidization described in example 13 was carried out using a stepwise temperature programming at a rate of 3 ℃/min, which was otherwise the same as in example 1, except that the temperature was changed to a stepwise temperature programming in the same manner as in example 1.
Example 14
The thermal imidization described in example 14 was carried out at a temperature rate of 5 ℃/min, which was the same as in example 1, except that the temperature was increased by a stepwise temperature programming as in example 1.
Comparative example 1
Unlike example 1, the molar ratio of ODA/PMDA described in comparative example 1 was 0.95, and the rest was the same as example 1.
Comparative example 2
Unlike example 1, the molar ratio of ODA/PMDA described in comparative example 2 was 1.1, and the rest was the same as example 1.
Comparative example 3
The polyamic acid solution described in comparative example 3 had a solid content of 7% and a viscosity of 200cp, which is different from example 1, and was otherwise the same as example 1.
Comparative example 4
Unlike example 1, the polyamic acid solution described in comparative example 4 had a solid content of 32% and a viscosity of 3100cp, which was otherwise the same as example 1.
Comparative example 5
The substrate of comparative example 5 was a glass substrate, and the boiling peeling method was used, which was different from example 1, and the other steps were the same as example 1.
Comparative example 6
The silicon carbide ceramic substrate of comparative example 6 had a roughness of 0.025 unlike example 1, but it was the same as example 1.
Comparative example 7
The silicon carbide ceramic substrate of comparative example 7 had a roughness of 0.2, which is different from example 1, and was otherwise the same as example 1.
Performance testing
(1) Ease of peeling: firstly, one corner of the film is uncovered, the film is uniformly peeled, and the difficulty degree of peeling the film is checked. The test standard is GBT25256-2010 test method for the peeling force and residual adhesion rate of the release film 180 of the optical functional film.
(2) Tensile strength: the tensile force at stretch break of a film per unit cross-section represents the ability of a material to resist stretching. The test standard is ISO 1184-1983 determination of tensile properties of plastic films.
(3) Elongation at break: the percentage increase in film length at break of the film sample when the film is subjected to a tensile test at break. The test standard is ISO 1184-1983 determination of tensile properties of plastic films
The test results for each of examples 1-14 and comparative examples 1-7 are shown in Table 1:
TABLE 1
As can be seen from Table 1, the invention can realize the rapid peeling of the polyimide film with a thinner thickness, and the polyimide film has higher tensile strength and elongation at break. According to the invention, the traditional glass substrate is replaced by the polished compact ceramic substrate, so that the polyimide film can be quickly stripped, and the polished ceramic substrate can be repeatedly used, is energy-saving and environment-friendly; meanwhile, the process is simple to operate, does not need to change the existing synthesis and processing equipment, and is easy for industrial production. According to the invention, the cured and cooled polyimide film is directly peeled off, so that the traditional glass substrate boiling peeling method is saved, the dehydration imidization of the polyimide film is inhibited, and the mechanical property of the polyimide film material is improved to a certain extent. In addition, in the step (S2) of the present invention, the dianhydride is added to the uniformly mixed diamine solution in multiple times, so that the dianhydride is promoted to be completely dissolved in the diamine solution, and when the diamine and the dianhydride are primarily polymerized to form the resin solution, the reaction is a reaction in which the exothermic entropy increases, and thus, the multiple addition of the dianhydride contributes to the polymerization reaction of the molecular chain segment, and the reaction is promoted to proceed in the forward direction, so that the molecular chain segment is continuously increased. The polyimide film has high surface smoothness, high temperature resistance and excellent mechanical property, and can be applied to the fields of flexible circuit boards, microelectronic packaging and the like, thereby having wide application prospect.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.
Claims (10)
1. The preparation method of the polyimide film is characterized by comprising the following steps:
(S1) uniformly stirring diamine and a polar solvent in inert gas to obtain a completely dissolved diamine solution;
(S2) adding dianhydride into the uniformly mixed diamine solution for multiple times, and performing cross-linking polymerization in inert gas to generate a polyamic acid solution;
and (S3) spin-coating the polyamic acid solution on the polished surface of the ceramic substrate, pre-drying to remove the solvent, and performing thermal imidization to obtain the polyimide film.
2. The method for producing a polyimide film according to claim 1, wherein the diamine is one or more selected from the group consisting of m-phenylenediamine (MPD), 1, 4-bis (4-amino-2-trifluoromethylphenoxy) benzene (6 FAPB), and 4,4' -diaminodiphenyl ether (ODA); the dianhydride is one or more of biphenyl tetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA) and hexafluoro dianhydride (FFDA); the polar solvent is one or more of N, N-Dimethylformamide (DMF), N-Dimethylacetamide (DMAC) and N-methyl pyrrolidone (NMP).
3. The method of claim 1, wherein the molar ratio of diamine to dianhydride is 0.96 to 1.0.
4. The method for preparing a polyimide film according to claim 1, wherein the temperature of the cross-linking polymerization reaction in the step (S2) is 10 to 50 ℃, and the reaction time is 8 to 12 hours; the inert gas is selected from one of helium, nitrogen and argon; preferably, the flow rate of the inert gas is 30 to 70mL/min.
5. The method for preparing a polyimide film according to claim 1, wherein the polyamic acid solution has a solid content of 10 to 30% and a viscosity of 300 to 3000cp.
6. The method for preparing polyimide film according to claim 5, wherein the ceramic substrate is selected from the group consisting of SiC and ZrO 2 Or Al 2 O 3 InOne kind of the material is selected; preferably, the surface roughness Ra of the ceramic substrate is 0.05 to 0.10.
7. The method for preparing a polyimide film according to claim 1, wherein the spin coating process parameter of (S3) is a stepwise increase in the rotation speed, and the stepwise increase in the rotation speed comprises: the first stage is spin coating at 200-300r/min for 20-30s; the second stage is that spin coating is carried out at 500-800r/min for 20-30s; the third stage is spin coating at 1000-1500r/min for 30-50s.
8. The method for preparing a polyimide film according to claim 1, wherein the thermal imidization is performed by a stepwise temperature programming at a rate of 2 ℃/min to 5 ℃/min;
preferably, the step temperature programming process is as follows: firstly, heating at 60-80 ℃ for 0.5-1h, raising the temperature to 140-160 ℃, and preserving the heat for 1-1.5h; then, heating to 240-260 ℃, and preserving heat for 1-1.5h; finally, the temperature is raised to 300-330 ℃ and the temperature is kept for 0.5-1h.
9. A polyimide film produced by the method for producing a polyimide film according to any one of claims 1 to 8.
10. Use of the polyimide film according to claim 9, wherein the polyimide film is used in a flexible display substrate.
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| CN117209823B (en) * | 2023-10-12 | 2024-03-22 | 太湖聚智新材料科技有限公司 | Preparation method of polyimide film |
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