Polyimide vibration film and production process thereof

Abstract

The invention discloses a polyimide vibration film and a production process thereof, and relates to the technical field of polyimide. According to the invention, a 2, 2-bis (trifluoromethyl)-4, 4-diaminodiphenyl monomer is introduced into 4, 4 '-diaminodiphenyl ether, 3, 3, 4, 4-diphenyl ether tetracarboxylic dianhydride, 3, 3, 4, 4-biphenyl dianhydride and pyromellitic dianhydride monomers as a fifth monomer to participate in copolymerization; the prepared polyimide film is excellent in mechanical property, low in dielectric constant, high in elongation at break and stable in voltage breakdown resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of polyimide, and particularly to a polyimide vibration film and its production process. Background Art

[0002] Polyimide refers to a class of polymers containing imide rings in the main chain, which have excellent electrical properties, mechanical properties, solvent resistance and high temperature resistance, and are thus widely used in the fields of aerospace, electronic information industry and microelectronics. Especially in the field of microelectronics, polyimide film, as a dielectric material with excellent flexibility, and after modification, has the characteristics of low dielectric constant, high temperature resistance, high elasticity and self-lubrication, and is an excellent material that is rare in the field of ultra-thin and ultra-light vibration films of some high-end audio.

[0003] The polyimide film applied on the isolation tape based on the requirement of TAB tape automated bonding has basically the same performance requirements as the high-frequency vibration polyimide film required for audio equipment. Currently, the carrier mainly used on the market is made of a double-layer tape with a polyimide film laminated on an aluminum foil, called Al-TAB, which is a very thin double-layer material with a thickness of about 50μm (the aluminum layer is about 30μm thick and the polyimide layer is about 20μm thick) and a width of about 100mm. This material requires the polyimide film to have a certain high elasticity and flexibility, and a low dielectric constant, where the aluminum layer acts as a conductor and the polyimide layer acts as a support and protection.

[0004] The application requirements of traditional polyimide films in terms of high plasticity and high elasticity are restricted. The main factors are that the tensile strength of polyimide is too high and the elongation at break is too low, and it is impossible to meet the requirements of high plasticity while ensuring the tensile strength, and at the same time ensure to meet the breakdown requirement of withstand voltage. In order to increase the elongation of ordinary polyimide films, the tensile strength of the film will be reduced, making the support of the film unable to meet the corresponding requirements; and in order to improve the breakdown resistance, the Young's modulus needs to be increased, which in turn makes the film as a whole too hard; currently on the market, mainly through foaming technology or filling inorganic particles, a support is introduced into the polyimide material to reduce the number of polarized molecules per unit volume of the polyimide material, thereby reducing its dielectric constant. The prior art uses spherical silicon to be compounded with a polyimide film, and then the spherical silicon is etched away by hydrofluoric acid, and the obtained porous polyimide film material has a dielectric constant as low as 1.6, but the mechanical properties of the film material obtained by this method deteriorate seriously and are only applicable in special fields.

[0005] In summary, how to make the polyimide film meet the requirements of high plasticity while ensuring the tensile strength, and at the same time ensure the breakdown resistance, is an urgent problem to be solved. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art and provide a polyimide vibration film and its production process. By introducing TFMB monomer to participate in copolymerization, the prepared polyimide film has excellent mechanical properties, low dielectric constant, high elongation at break, and stable withstand voltage breakdown performance.

[0007] The technical solution of the present invention is as follows: On the one hand, the present invention provides a production process of a polyimide vibration film, including the following steps: S1: Using 4,4'-diaminodiphenyl ether (ODA), 3,3,4,4-diphenyl ether tetracarboxylic dianhydride (ODPA), 3,3,4,4-biphenyl dianhydride (BPDA) and pyromellitic dianhydride (PMDA) as the base materials, adding them to an organic solvent and stirring to dissolve, and adjusting the solid content to 18 - 20 wt.%, stirring and reacting at room temperature for 8 - 10 h to obtain a prepolymer solution; S2: After dissolving 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl (TFMB) in an organic solvent, a 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl solution is obtained. Injecting it into the prepolymer solution to obtain a fluorinated polyamic acid solution (FPAA) with a solid content of 20 - 22 wt.%, deaerating and then pressure-filtering it into a storage tank for temporary storage; S3: Mix acetic anhydride and isoquinoline into an organic solvent respectively, deaerating and then pressure-filtering them into their respective storage tanks for temporary storage; among them, acetic anhydride is a dehydrating agent and isoquinoline is a catalyst. When FPAA undergoes imidization at low temperature, adding isoquinoline can accelerate the imidization. During the process of accelerating the imidization, the dehydration reaction will also accelerate, and acetic anhydride is needed to assist in removing water molecules; S4: Transport the three materials in the storage tanks of step S2 and step S3 to the needle-bar mixer above the die head. After fully mixing at -15~-5 °C, coat them onto a circular mirror steel belt through the slit die head of the casting machine. The circular steel belt is dried in the casting machine to complete the preliminary imidization film shaping, and then imidization is completed after shaping by a stretching machine, and finally wound up to obtain the polyimide vibration film.

[0008] When mixing acetic anhydride, isoquinoline and FPAA in the needle-bar mixer, high-speed friction will generate heat, which will accelerate the catalytic speed of isoquinoline and the dehydration speed of acetic anhydride in the needle-bar mixer. In order to prevent the catalytic and dehydration reactions of imidization in the needle-bar mixer and the die head, acetic anhydride, isoquinoline and FPAA are mixed at a low temperature of -15~-5 °C to prevent the reaction from occurring.

[0009] When preparing a polyimide film by a chemical method, in a casting machine, hot air at 135°C is used for dehydration imidization in the upper layer, and hot air at 145°C is used for solvent removal in the lower layer. During the imidization process, water molecules are accelerated to be removed through the dehydrating agent acetic anhydride. Since at 135°C, the solvent in the upper layer has not been removed yet and the solid content has no significant change, the surface of the film is not cured or sealed, and water molecules can easily fly out. In this way, the evaporation rate of water molecules is fast, the degree of imidization is high, and most of the imidization is completed in the casting machine. After the film coming out of the casting machine enters the stretching machine, the remaining solvent of the film is evaporated by the high temperature of the stretching machine, and the remaining small part of the imidization reaction is synchronously completed, the isomers inside the film are removed, and the size is stabilized, and finally a fully imidized polyimide film is obtained.

[0010] Preferably, the specific process of step S1 is as follows: 4,4'-diaminodiphenyl ether (ODA), 3,3,4,4-diphenyl ether tetracarboxylic dianhydride (ODPA), 3,3,4,4-biphenyl dianhydride (BPDA) and pyromellitic dianhydride (PMDA) are respectively dissolved in an organic solvent in separate monomer tanks under nitrogen protection; the obtained solution of 3,3,4,4-biphenyl dianhydride (BPDA) is put into the first reactor, and after stirring evenly, the solution of 4,4'-diaminodiphenyl ether (ODA) and the solution of 3,3,4,4-diphenyl ether tetracarboxylic dianhydride (ODPA) are gradually added. After stirring, the solution of pyromellitic dianhydride (PMDA) is gradually added again. After stirring evenly for 8 - 10 h until the designed viscosity is reached, a uniformly mixed prepolymer solution is obtained under nitrogen protection; after defoaming, it is pressure-filtered into a storage tank for temporary storage.

[0011] Preferably, in the base material, the molar ratio of 4,4'-diaminodiphenyl ether (ODA), 3,3,4,4-biphenyl dianhydride (BPDA), 3,3,4,4-diphenyl ether tetracarboxylic dianhydride (ODPA) to pyromellitic dianhydride (PMDA) is 1:(0.3 - 0.39):(0.3 - 0.39):(0.3 - 0.34), and the molar ratio of acid anhydride to amino group is 0.99:1.

[0012] Preferably, the designed viscosity is 450,000 - 500,000 mPa·s at 25°C.

[0013] Preferably, the specific process of step S2 is as follows: 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl (TFMB) is added to an organic solvent and stirred until dissolved to obtain a solution of 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl under nitrogen protection; the solution of 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl is injected into the prepolymer solution and adjusted to the designed viscosity to obtain a fluorine-containing polyamic acid solution (FPAA) under nitrogen protection.

[0014] Preferably, in step S2, the molar ratio of the solid in the fluorinated polyamic acid solution to 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl is 1:(0.02 - 0.04).

[0015] Preferably, the designed viscosity is 1 million - 1.2 million mPa·s at 25°C.

[0016] Preferably, in step S3, acetic anhydride is 30 - 35 times the mass of the base material, the mass ratio of acetic anhydride to the organic solvent is (0.8 - 1):(2.2 - 2.8), isoquinoline is 5.5 - 6.5 times the mass of the base material, and the mass ratio of isoquinoline to the organic solvent is (0.8 - 1):(3 - 5).

[0017] Preferably, the upper layer drying temperature of the casting machine is 135°C, and the lower layer drying temperature is 145°C; the setting temperature of the stretching machine is: 180 - 220°C in the first zone hot air section, 200 - 240°C in the second zone hot air section, 240 - 260°C in the third zone infrared section, and 220 - 270°C in the fourth zone infrared section. By using the rigid monomers (ODPA and BPDA) in the quaternary monomer and their addition amounts in the present invention, a polyimide vibration film with excellent performance can be obtained at a relatively low setting temperature.

[0018] On the other hand, the present invention provides a polyimide vibration film produced by the above production process of the polyimide vibration film.

[0019] Compared with the prior art, the present invention has the following beneficial effects: When producing the polyimide vibration film in the present invention, by introducing the TFMB monomer to participate in copolymerization, the main chain of the polymer is still mainly composed of polyimide chains, so that there is no obvious change in the glass transition temperature and high-temperature weight loss of the polymer. However, as the fifth monomer is introduced, the TFMB monomer breaks the regularity of the polyimide main chain, resulting in a decrease in the crystallization temperature of the polymer, making it easier to process the film material. Such fluorinated monomers have a cyclic structure, with a relatively large free volume itself, and the fluorine structure has a segregation effect with the polyimide main chain. Therefore, through the fluorobenzene structure of the TFMB side chain, a spatial knot is formed on the side chain of the polymerization link of the fluorinated polyamic acid solution, further increasing the free volume, so that the dielectric constant of the prepared fluorinated polyimide film can be as low as 1.74. At the same time, after imidization, the molecular chains of the polyimide film are closely structured, with excellent mechanical properties, making it not only have a low dielectric constant, but also have the characteristics of high temperature resistance, high elasticity, and self-lubrication. It can always maintain a high elongation at break at 200°C, and has stable voltage breakdown resistance and a low dielectric constant under the automatic welding condition after being combined with an aluminum sheet. Description of the Drawings

[0020] Figure 1It is the DSC curve of the polyimide vibration film prepared in Example 1 of the present invention.

[0021] Figure 2 It is the thermal decomposition curve of the polyimide vibration film prepared in Example 1 of the present invention. Detailed implementation manners

[0022] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention.

[0023] Example 1 The production process of the polyimide vibration film in this example includes the following steps: S1: Take ODA, BPDA, ODPA, and PMDA and dissolve them separately in a monomer tank with DMF, and introduce nitrogen for protection; put the obtained BPDA solution into the first reactor, stir evenly, and then gradually add the ODA solution and the ODPA solution. The molar ratio of ODA, BPDA, and ODPA is 1:0.39:0.3. After stirring, gradually add the PMDA solution. The molar ratio of PMDA to ODA is 0.3:1. Control the molar ratio of anhydride to amino group to be 0.99:1, and adjust the solid content to 18 wt.%. Stir and react at room temperature for 9 h to obtain a prepolymer solution with a viscosity of 500,000 mPa·s (25 °C), and introduce nitrogen for protection; after defoaming, filter press it into a storage tank for temporary storage; S2: Add TFMB to DMF and stir to dissolve it to obtain a TFMB solution, and introduce nitrogen for protection; inject it into the prepolymer solution to obtain a fluorinated polyamic acid solution (FPAA) with a solid content of 20 wt.% and a viscosity of 1,000,000 mPa·s (at 25 °C). The molar ratio of the solid in FPAA to TFMB is 1:0.04, and introduce nitrogen for protection; transfer it to a defoaming kettle for defoaming, and after completion, filter press it into a storage tank for temporary storage; S3: Add acetic anhydride and isoquinoline to DMF respectively and mix them evenly. The dosage of acetic anhydride is 30 times the mass of the base material. The mass ratio of acetic anhydride to DMF is 1:2.8. The dosage of isoquinoline is 5.5 times the mass of the base material. The mass ratio of isoquinoline to DMF is 1:5. After defoaming, filter press it into their respective storage tanks for temporary storage; S4: Use a metering pump to transport the three materials in the storage tanks of Step S2 and Step S3 to the needle bar mixer above the die head. After fully mixing at -5 °C, coat it onto a circular mirror steel belt through the slit die head of the casting machine. After the circular steel belt is dried in the upper and lower layers at 135 °C and 145 °C in the casting machine, the preliminary imidized film is shaped. Then, after being shaped in the first zone hot air section at 220 °C, the second zone hot air section at 230 °C, the third zone infrared section at 260 °C, and the fourth zone infrared section at 270 °C of the stretching machine, the imidization is completed, and finally, it is wound up to obtain the polyimide vibration film.

[0024] Example 2 The production process of the polyimide vibration film of this embodiment includes the following steps: S1: Take ODA, BPDA, ODPA, and PMDA and dissolve them with DMF in separate monomer tanks, and pass nitrogen for protection; put the obtained BPDA solution into the first reactor, stir at a uniform speed, and gradually add ODA solution and ODPA solution. The molar ratio of ODA, BPDA, and ODPA is 1:0.35:0.34. After stirring, gradually add PMDA solution. The molar ratio of PMDA to ODA is 0.3:1. The molar ratio of anhydride and amine is controlled to be 0.99:1, and the solid content is adjusted to 18wt.%. Stir and react at room temperature for 8h to obtain a prepolymer solution with a viscosity of 480,000 mPa·s (25°C), and pass nitrogen for protection; after degassing, filter and store in a storage tank temporarily; S2: After adding TFMB into DMF and stirring to dissolve, a TFMB solution is obtained, and nitrogen is passed through for protection; the solution is injected into the prepolymer solution to obtain a fluorinated polyamic acid solution (FPAA) with a solid content of 20wt.% and a viscosity of 1.1 million mPa·s (at 25°C), wherein the molar ratio of the solid in FPAA to TFMB is 1:0.03, and nitrogen is passed through for protection; the solution is transferred to a defoaming kettle for degassing, and after completion, the solution is filtered and temporarily stored in a storage tank; S3: Add acetic anhydride and isoquinoline to DMF respectively and mix well, the amount of acetic anhydride is 35 times the mass of the base material, the mass ratio of acetic anhydride to DMF is 0.9:2.5, the amount of isoquinoline is 6 times the mass of the base material, the mass ratio of isoquinoline to DMF is 0.9:4, and filter and filter into respective storage tanks for temporary storage after defoaming; S4: The three materials in the storage tanks of step S2 and step S3 are conveyed to the needle-bar mixer above the die head by a metering pump. After being fully mixed at -10°C, they are coated onto an annular mirror steel belt through a slit extrusion die of a casting machine. The annular steel belt is dried in two layers at 135°C and 145°C in the casting machine to complete the preliminary imidization film shaping. After that, the imidization is completed after being shaped by the first hot air section of the stretching machine at 200°C, the second hot air section at 240°C, the third infrared section at 240°C, and the fourth infrared section at 260°C. Finally, the polyimide vibration film is rolled up.

[0025] Example 3 The production process of the polyimide vibration film of this embodiment includes the following steps: S1: Take ODA, BPDA, ODPA, and PMDA and dissolve them with DMF in separate monomer tanks, and pass nitrogen for protection; put the obtained BPDA solution into the first reactor, stir at a uniform speed, and gradually add ODA solution and ODPA solution. The molar ratio of ODA, BPDA, and ODPA is 1:0.3:0.39. After stirring, gradually add PMDA solution. The molar ratio of PMDA to ODA is 0.3:1. The molar ratio of anhydride and amine is controlled to be 0.99:1, and the solid content is adjusted to 20wt.%. Stir and react at room temperature for 10h to obtain a prepolymer solution with a viscosity of 450,000 mPa·s (25°C), and pass nitrogen for protection; after degassing, filter and store in a storage tank temporarily; S2: After adding TFMB into DMF and stirring to dissolve, a TFMB solution is obtained, and nitrogen is passed through for protection; the solution is injected into the prepolymer solution to obtain a fluorinated polyamic acid solution (FPAA) with a solid content of 22wt.% and a viscosity of 1.2 million mPa·s (at 25°C), wherein the molar ratio of the solid in FPAA to TFMB is 1:0.02, and nitrogen is passed through for protection; the solution is transferred to a defoaming kettle for degassing, and after completion, the solution is filtered and temporarily stored in a storage tank; S3: Add acetic anhydride and isoquinoline to DMF respectively and mix well, the amount of acetic anhydride is 32 times the mass of the base material, the mass ratio of acetic anhydride to DMF is 0.8:2.2, the amount of isoquinoline is 6.5 times the mass of the base material, the mass ratio of isoquinoline to DMF is 0.8:3, and filter and filter after defoaming and store in respective storage tanks temporarily; S4: The three materials in the storage tanks of step S2 and step S3 are conveyed to the needle-bar mixer above the die head by a metering pump. After being fully mixed at -15°C, they are coated onto an annular mirror steel belt through a slit extrusion die of a casting machine. The annular steel belt is dried in two layers at 135°C and 145°C in the casting machine to complete the preliminary imidization film shaping. After that, the imidization is completed after being shaped by the first hot air section of the stretching machine at 180°C, the second hot air section at 200°C, the third infrared section at 250°C, and the fourth infrared section at 260°C. Finally, the polyimide vibration film is rolled up.

[0026] Example 4 The production process of the polyimide vibration film of this embodiment includes the following steps: S1: Dissolve ODA, BPDA, ODPA, and PMDA separately with DMF in individual monomer tanks, and introduce nitrogen for protection; put the obtained BPDA solution into the first reactor, stir evenly, and gradually add the ODA solution and ODPA solution. The molar ratio of ODA, BPDA, and ODPA is 1:0.35:0.3. After stirring, gradually add the PMDA solution. The molar ratio of PMDA to ODA is 0.34:1. Control the molar ratio of anhydride to amino group to 0.99:1, and adjust the solid content to 20 wt.%. Stir and react at room temperature for 8 h to obtain a prepolymer solution with a viscosity of 480,000 mPa·s (25 °C), and introduce nitrogen for protection; after degassing, filter press it into a storage tank for temporary storage; S2: Add TFMB to DMF and stir to dissolve it to obtain a TFMB solution, and introduce nitrogen for protection; inject it into the prepolymer solution to obtain a fluorinated polyamic acid solution (FPAA) with a solid content of 20 wt.% and a viscosity of 1,100,000 mPa·s (at 25 °C). The molar ratio of the solid in FPAA to TFMB is 1:0.02, and introduce nitrogen for protection; transfer it to a defoaming kettle for defoaming, and after completion, filter press it into a storage tank for temporary storage; S3: Add acetic anhydride and isoquinoline to DMF respectively and mix evenly. The dosage of acetic anhydride is 30 times the mass of the base material, DMF is 2.8 times the mass of acetic anhydride, the dosage of isoquinoline is 5.5 times the mass of the base material, and DMF is 5 times the mass of isoquinoline. After defoaming, filter press it into their respective storage tanks for temporary storage; S4: Use a metering pump to transport the three materials in the storage tanks in steps S2 and S3 to the needle bar mixer above the die head. After fully mixing at -5 °C, coat it onto a circular mirror steel belt through the slit die head of a casting machine. After the circular steel belt is dried in the upper and lower layers at 135 °C and 145 °C in the casting machine, the preliminary imidized film is shaped. After being shaped in the first hot air section at 220 °C, the second hot air section at 240 °C, the third infrared section at 260 °C, and the fourth infrared section at 220 °C of the stretching machine, the imidization is completed, and finally, it is wound up to obtain a polyimide vibration film.

[0027] Comparative Example 1 The difference from Example 1 is that step S2 is not carried out, and the material in step S2 transported to the needle bar mixer above the die head in step S4 is replaced with the prepolymer solution in step S1.

[0028] Comparative Example 2 In Comparative Example 2, a polyimide film was prepared by doping sintered spherical silicon, and the specific steps are as follows: (1) Take sintered spherical silicon (SiO2 type raw material provided by Japan EIT Co., Ltd.), ultrasonically disperse it with 5 times its mass of DMF, add 3% of the silane coupling agent KH550 based on the mass of the dispersion liquid, and stir at room temperature for 1 h to obtain coupled spherical silicon; (2)Following the steps of S1 in Example 4, a prepolymer solution was obtained; (3)Following the steps of S2 in Example 4, coupling spherical silica was used instead of TMFB, and 6.5% of the mass of the base material of coupling spherical silica was added to the prepolymer solution; (4)Same as steps S3 and S4 in Example 4.

[0029] Samples were taken from the polyimide vibration films prepared in Examples 1 - 4 and Comparative Examples 1 - 2 for performance testing. The testing methods are as follows: 1) DSC testing was carried out on it using a DSC-Q100 instrument: in a nitrogen atmosphere with a flow rate of 50 mL / min, the sample was heated from 60°C to 270°C at a heating rate of 10°C / min, held for 1 min, then cooled to 60°C at a cooling rate of 10°C / min, and then the above heating and cooling operations were repeated. The values of the second heating curve and cooling curve were taken as experimental data. The glass transition temperature T of the polyimide vibration film of Example 1 was measured. g As Figure 1 shown, from Figure 1 it can be seen that the glass transition temperature T of the polyimide vibration film of Example 1 g = 277°C.

[0030] 2) Tensile property testing of the sample was carried out using a SHIMADZU AG-I universal testing machine: at room temperature with a tensile rate of 5 mm / min.

[0031] 4) Dielectric constant testing of the sample was carried out using a JKY / 1920 / M315427 LCR instrument: the testing temperature was 25°C and the frequency was 1 - 1000 kHz.

[0032] The performance test results of the polyimide vibration films prepared in Examples 1 - 4 and Comparative Examples 1 - 2 are shown in Table 1: Table 1 Performance test results of the polyimide vibration films prepared in Examples 1 - 4 and Comparative Examples 1 - 2

[0033] As can be seen from Table 1, compared with Comparative Example 1, for the film materials prepared in Examples 1 - 4, with the addition of the monomer TFMB, the dielectric constant decreased significantly. The dielectric constant at 1 MHz was only 1.74 - 1.99, having a lower dielectric constant, making it easier to process during actual application.

[0034] As can be seen from Table 1, for Comparative Example 2 without the addition of TFMB, sintered spherical silica was added, which could reduce the dielectric constant of the film surface. However, the addition of inorganic fillers would lead to poor length of the functional bond chains, and the tensile strength and elongation at break of the film were not as good as those of the monomer TFMB that could undergo a bonding reaction.

[0035] Through the polymerization of multiple monomers, the present invention copolymerizes using rigid and semi-rigid anhydride groups and amino groups to obtain a polymer material with excellent tensile properties and plasticity coexisting. It can be used for a long time at 200-260°C. When used as a vibrating piece inside a speaker, it can maintain high elasticity and high stiffness for a long time.

[0036] The polyimide vibration film prepared in Example 1 was subjected to a thermal decomposition test, and the obtained thermal decomposition curve is as Figure 2 shown.

[0037] From Figure 2 it can be seen that for the film material obtained by introducing the TFMB monomer in Example 1, the thermal decomposition temperature meets the requirement of over 500°C. It can always maintain stable high-temperature resistance and excellent protection function of high stiffness on the isolation tape for AI-TAB automatic soldering, and can effectively and temperature-resistant support and protect the chip surface.

Claims

1. The production process of a polyimide vibration film, characterized in that, The following steps are involved: S1: 4,4'-diaminodiphenyl ether, 3,3,4,4-diphenyl ether tetracarboxylic dianhydride, 3,3,4,4,-biphenyl dianhydride and pyromellitic dianhydride are added as base materials into an organic solvent, stirred and dissolved, and the solid content is adjusted to 18-20wt.%, stirred and reacted at room temperature for 8-10h to obtain a prepolymer solution; S2: adding 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl to an organic solvent and stirring to dissolve, thereby obtaining a 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl solution, injecting the solution into a prepolymer solution, and obtaining a fluorinated polyamic acid solution having a solid content of 20-22 wt.%, and then degassing and filtering the solution to a storage tank for temporary storage; S3: adding acetic anhydride and isoquinoline to the organic solvent respectively, mixing evenly, defoaming, and filtering by pressure into respective storage tanks for temporary storage; S4: The three materials in the storage tanks of step S2 and step S3 are conveyed to the pin-bar mixer above the die head, and after being fully mixed at -15~-5°C, they are coated onto an annular mirror steel belt through a slit extrusion die of a casting machine. The annular steel belt is dried in the casting machine to complete the preliminary imidization film shaping, and then the imidization is completed after shaping by a stretching machine, and finally rolled up to obtain a polyimide vibration film.

2. The production process of the polyimide vibration film according to claim 1, characterized in that, The specific process of step S1 is as follows: 4,4'-diaminodiphenyl ether, 3,3,4,4-diphenyl ether tetracarboxylic dianhydride, 3,3,4,4,-biphenyl dianhydride and pyromellitic dianhydride are dissolved in separate monomer tanks with organic solvents, respectively, and nitrogen is introduced for protection; the obtained 3,3,4,4,-biphenyl dianhydride solution is put into the first reactor, after uniform stirring, 4,4'-diaminodiphenyl ether solution and 3,3,4,4-diphenyl ether tetracarboxylic dianhydride solution are gradually added, after stirring, pyromellitic dianhydride solution is gradually added, and after uniform stirring for 8-10 hours until the designed viscosity is reached, a uniformly mixed prepolymer solution is obtained, and nitrogen is introduced for protection.

3. The production process of the polyimide vibration film according to claim 1 or 2, characterized in that, In the base material, the molar ratio of 4,4'-diaminodiphenyl ether, 3,3,4,4,-biphenyl dianhydride, 3,3,4,4-diphenyl ether tetracarboxylic dianhydride and pyromellitic dianhydride is 1:(0.3-0.39):(0.3-0.39):(0.3-0.34), and the molar ratio of anhydride to amine is 0.99:

1.

4. The production process of the polyimide vibration film according to claim 2, characterized in that, The design viscosity is 450,000-500,000 mPa·s at 25°C.

5. The production process of the polyimide vibration film according to claim 1, characterized in that, The specific process of step S2 is as follows: adding 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl to an organic solvent and stirring to dissolve, thereby obtaining a 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl solution, and introducing nitrogen for protection; injecting the 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl solution into the prepolymer liquid, adjusting the viscosity to the designed viscosity, obtaining a fluorinated polyamic acid liquid, and introducing nitrogen for protection; after degassing, filtering and temporarily storing in a storage tank.

6. The production process of the polyimide vibration film according to claim 1 or 5, characterized in that, In step S2, the molar ratio of the solid in the fluorinated polyamic acid solution to 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl is 1:(0.02-0.04).

7. The production process of the polyimide vibration film according to claim 5, characterized in that, The design viscosity is 1 million to 1.2 million mPa·s at 25°C.

8. The production process of the polyimide vibration film according to claim 1, characterized in that, In step S3, the acetic anhydride is 30 - 35 times the mass of the base material, the mass ratio of acetic anhydride to the organic solvent is (0.8 - 1):(2.2 - 2.8), the isoquinoline is 5.5 - 6.5 times the mass of the base material, and the mass ratio of isoquinoline to the organic solvent is (0.8 - 1):(3 - 5).

9. The production process of the polyimide vibration film according to claim 1, characterized in that, The drying temperature of the upper layer of the casting machine is 135 °C, and the drying temperature of the lower layer is 145 °C; the setting temperature of the stretching machine is: 180 - 220 °C in the hot air section of the first zone, 200 - 240 °C in the hot air section of the second zone, 240 - 260 °C in the infrared section of the third zone, and 220 - 270 °C in the infrared section of the fourth zone.

10. A polyimide vibrating film, characterized in that, It is produced by the production process of the polyimide vibration film according to any one of claims 1 - 9.

Images