CN109666170B - Preparation method of uniform high-performance polyimide film - Google Patents
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- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1067—Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound
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- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1067—Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound
- C08G73/1071—Wholly aromatic polyimides containing oxygen in the form of ether bonds in the main chain
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- C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
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Abstract
The invention provides a preparation method of a uniform high-performance polyimide film, which mainly solves the problems that in the prior art, the surface of the polyimide film is not uniform, and more gel particles cause difficulty in controlling the film preparation process and the product performance is reduced. The preparation method of the uniform high-performance polyimide film and the preparation method of the polyimide film are prepared by forming a polyamic acid stock solution, thermally stretching and thermally imidizing; the polyamide acid stock solution comprises a mixed solution of a prepolymer solution 1 and a prepolymer solution 2; the prepolymer solution 1 is obtained by reacting a reactant comprising X mol of diamine and Y mol of dianhydride; the prepolymer solution 2 is obtained by reacting reactants comprising Z mol of diamine and K mol of dianhydride; x, Y, Z, K satisfies the following conditions: the technical proposal that Y/X is more than or equal to 0.5 and less than or equal to 0.98 and K/Z is more than or equal to 1.02 and less than or equal to 2.0 better solves the problem and can be used in the industrial production of polyimide films.
Description
Technical Field
The invention relates to a preparation method of a uniform high-performance polyimide film with a smooth surface and excellent performance.
Background
The polyimide material is used as engineering plastic which is industrially produced and has the best heat resistance, has the characteristics of excellent thermal stability, mechanical property, low temperature resistance, outstanding insulating property, solvent resistance and the like, and has wide application in the fields of aerospace, electronics, microelectronics, mechanical and chemical engineering and the like. Polyimide film is one of the most demanded polyimide products, and its excellent corona resistance, radiation resistance, dielectric properties and dimensional stability make the demand for high-performance polyimide film materials continuously increasing.
Due to a large number of imide rings and benzene ring structures in the polyimide main chain, strong intermolecular force exists among molecular chains, so that the polyimide molecular chain structure is compact, the characteristics of difficult dissolution and difficult dissolution are shown, the barrier of mass production and processing of polyimide is formed, and the development of polyimide film products in more application fields is influenced. In order to avoid the problem of solubility, the production of the polyimide film mainly adopts a two-step method, wherein a polyamic acid solution is synthesized, and then the polyimide film is prepared by a tape-casting film forming process of a pre-drying process and a thermal imidization treatment.
Polyamic acids are typically prepared by reacting a dianhydride with a diamine in an aprotic polar solvent at low temperatures. The patent reports that the relative molecular mass can be adjusted by adding more or less dianhydride monomers or hydrolyzing a part of dianhydride by using an aqueous solvent, however, the polyamide acid solution prepared by the polymerization method has the defects of poor solution uniformity, wide molecular weight distribution and the like, and the uniformity and the processing stability of the prepared polyimide film are seriously influenced.
Disclosure of Invention
The invention aims to solve the problems of uneven polyimide film surface, unstable process and reduced product quality caused by uneven polyamic acid solution and wider molecular weight distribution. The invention provides a preparation method of a uniform high-performance polyimide film, the polyimide film prepared by the method has uniform surface and excellent performance, the processing process is easy to stably control, the product is not easy to generate defects, and a high-performance polyimide product can be obtained.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a method for preparing uniform high-performance polyimide film is prepared by film forming, hot stretching and hot imidization of polyamic acid stock solution; the polyamide acid stock solution comprises a mixed solution of a prepolymer solution 1 and a prepolymer solution 2; the prepolymer solution 1 is obtained by reacting a reactant comprising X moles of diamine and Y moles of dianhydride; the prepolymer solution 2 is obtained by reacting reactants comprising Z mol of diamine and K mol of dianhydride; the X, Y, Z, K satisfies: Y/X is more than or equal to 0.5 and less than or equal to 0.98, and K/Z is more than or equal to 1.02 and less than or equal to 2.0.
In the above technical solution, the preparation method preferably comprises the following steps:
(1) preparing stock solution:
a) dissolving X mol of diamine in an organic solvent, and adding Y mol of dianhydride into a diamine solution to react to obtain a prepolymer solution 1;
b) dissolving diamine in Z mol in an organic solvent, and adding dianhydride in K mol into a diamine solution to react to obtain a prepolymer solution 2;
c) adding the prepolymer solution 2 into the prepolymer solution 1, uniformly mixing, and then filtering and defoaming to obtain a polyamide acid stock solution;
(2) casting and film forming: controlling the thickness of the polyamic acid stock solution obtained in the step (1) through a scraper, and carrying out tape casting on a smooth steel belt to obtain a polyamic acid wet film;
(3) pre-drying treatment: enabling the polyamic acid wet film obtained in the step (2) to pass through a constant-temperature heating furnace in an inert gas atmosphere to obtain a self-supporting polyamic acid film, wherein the pre-drying treatment temperature is 50-150 ℃;
(4) hot stretching: longitudinally stretching and transversely stretching the polyamic acid film obtained in the step (3) to obtain a stretched polyamic acid film, wherein the stretching temperature is 100-300 ℃;
(5) thermal imidization: and (3) performing thermal imidization on the stretched polyamide acid film obtained in the step (4) to obtain a high-performance polyimide film, wherein the thermal imidization temperature is 200-500 ℃.
In the above technical solution, the polyamic acid is selected from the structures represented by the general formula (1):
wherein Ar is1Is a tetravalent aromatic residue having at least one carbon six-membered ring, and is more preferably an aromatic residue represented by the following formula (1)
Ar2Preferably a tetravalent aromatic residue comprising at least one carbon six-membered ring, more preferably an aromatic residue represented by the following structural formula (2):
in the above structural formula (2), R2H-, CH-, is preferably selected3-、Cl-、Br-、F-、CH3O-, etc.
In the technical scheme, the total molar ratio of dianhydride monomer to diamine monomer in the polyamic acid stock solution is 0.95-1.05: 1.
in the technical scheme, the stock solution preparation in the step (1) is preferably carried out under the protection of inert gas; the organic solvent may be any one of the prior art organic solvents known to those skilled in the art, and is preferably at least one of strong polar aprotic solvents such as N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and sulfolane; the reaction temperature in the step a) and the step b) is-10-40 ℃, and preferably 0-30 ℃; the solid content of the obtained polyamic acid stock solution is 5-30%, and more preferably 10-20%; the inert gas is preferably at least one of nitrogen, argon or helium; the reaction stirring speed is usually 50-600 revolutions per minute, preferably 100-400 revolutions per minute; the addition rate of prepolymer solution 2 in step c) preferably satisfies the following formula:
it is further preferable that the following formula is satisfied:
in the above technical solution, the water content in the organic solvent is preferably less than 800ppmw, and more preferably 100ppmw to 300 ppmw.
In the technical scheme, the filtering process of the polyamic acid stock solution adopts a multistage filtering method, and the precision is 0.1-10 mu m.
In the technical scheme, the defoaming process is vacuum defoaming, so that the defoaming efficiency is improved.
In the technical scheme, the tape-casting film forming process is controlled by a scraper, the thickness of a polyamic acid wet film is 40-3000 mu m, and the final thickness of a film product is different due to the change of the wet film thickness.
In the technical scheme, the pre-drying treatment process is carried out in the protection of nitrogen airflow, the pre-drying treatment temperature is 50-150 ℃, and 60-100 ℃ is preferred in consideration of production efficiency and energy cost.
In the technical scheme, the thermal stretching temperature of the polyamic acid self-supporting film is 100-300 ℃; the thermal imidization is a multi-stage heating process, and the imidization temperature is 200-500 ℃, preferably 250-400 ℃.
In the technical scheme, the longitudinal stretching multiple is preferably 1.0-2.2 times; the transverse stretching multiple is preferably 1.0-2.0 times.
The test equipment and test conditions used in the present invention are:
molecular weight and molecular weight distribution: a DMF solution sample of PAA at 1mg/ml was prepared using Agilent PL-GPC 200 high temperature GPC with DMF as the mobile phase, and the molecular weight and distribution of PAA were measured at a constant temperature of 35 ℃.
Apparent viscosity: BROOKFIELD DV-III ULTRA PROGRAMMABLE RHEOMETER, USA, and tests are carried out at 25 deg.C by using LV-4 trochanter.
Thermal decomposition temperature: the thermal decomposition temperature is set as the temperature of 5 wt% of thermal weight loss by adopting Discovery TGA of TA company in America and raising the temperature to 800 ℃ at the speed of 10 ℃/min under the nitrogen atmosphere.
Glass transition temperature: the TA company Q800 in USA carries out DMA test, and the temperature is raised to 600 ℃ at the speed of 10 ℃/min under the condition of nitrogen, and the peak temperature of the change curve of the loss tangent of the sample is obtained and is the glass transition temperature of the film.
Coefficient of thermal expansion: the film samples were tested for dimensional stability by TA corporation of america Q400. Heating at a speed of 10 ℃/min under a constant tension of 0.05N, eliminating thermal history in the first heating process, taking data between 50 and 200 ℃ in the second heating process, and calculating a Coefficient of Thermal Expansion (CTE) according to the slope to represent the dimensional stability of the PI film.
And (3) mechanical tensile test of the film: the films were formed into dumbbell-shaped test bars having a test width of 5mm, and tensile testing was carried out at a constant tensile rate of 100mm/min until the bars broke, using a universal material tester 3344 from Instron, USA, and the tensile strength and elongation at break of the samples were recorded.
By adopting the technical scheme of the invention, the obtained polyimide film has smooth surface and few defects when observed by a microscope, the thickness uniformity of the tested film is good, the tensile strength is 250-500 MPa, the elongation at break is 5-50%, the temperature of 5% of thermal decomposition reaches about 600 ℃, the glass transition temperature is 300-450 ℃, the thermal expansion coefficient is 5-50 ppm/K, the polyimide film can be used for a long time at a higher temperature without decomposition and can keep stable dimension, the polyimide film meets the application requirements of various fields on high-performance polyimide films, and a better technical effect is obtained.
Detailed Description
[ example 1 ]
1. Preparing stock solution: 0.973kg (9mol) of PDA was dissolved in 19kg of DMAc, stirred at 25 ℃ and completely dissolved, 2.383kg (8.1mol) of BPDA was added, and the mixture was reacted sufficiently to obtain a prepolymer solution 1 (dianhydride/diamine molar ratio 0.9, solid content 15%, the same applies). Prepolymer solution 2 (molar ratio 1.65, solids content 15%) was prepared in the same manner using 0.108kg (1mol) of PDA, 3.363kg of DMAc, 0.4854kg (1.65mol) of BPDA. Prepolymer solution 2 was added to prepolymer solution 1 at a rate of 2.0kg/h, and the mixture was thoroughly stirred at 25 ℃ to obtain the final polyamic acid solution (molar ratio 0.975, solid content 15%). The apparent viscosity of the final solution was measured to be 23 pas. After the solution was passed through a 2 μm glass fiber filter, the filter was free of foreign matter under irradiation of an ultraviolet fluorescent lamp. Filtering the polyamic acid solution by a filter material with the diameter of 5 mu m and the diameter of 0.5 mu m, and then carrying out vacuum defoamation to obtain polyamic acid film-forming stock solution.
2. Casting and film forming: the polyamic acid stock solution was cast into a film on a smooth steel belt by passing through a doctor blade to control the wet film thickness to 500 μm.
3. Pre-drying treatment: and (3) under the flowing atmosphere of nitrogen, passing through a hot furnace at 100 ℃ to remove most of the solvent, thus obtaining the self-supporting polyamic acid film.
4. Hot stretching: the self-supporting polyamic acid film was subjected to 1.8-fold longitudinal stretching and 1.8-fold transverse stretching at 160 ℃ to obtain a stretched polyamic acid film.
5. Thermal imidization: the stretched polyamic acid film is subjected to multistage heating and thermal imidization to obtain a high-performance polyimide film, and the high-performance polyimide film is subjected to imidization at 200 ℃ in a first temperature zone, 300 ℃ in a second temperature zone and 400 ℃ in a third temperature zone sequentially. And (6) slitting and rolling.
The PI film obtained by microscope observation has a flat surface without defects, excellent thickness uniformity in test, a tensile strength of 442MPa, an elongation at break of 15%, a thermal decomposition temperature of 5% of 605 ℃, a glass transition temperature of 441 ℃ and a thermal expansion coefficient of 2.2 ppm/K.
[ example 2 ]
1. Preparing stock solution: 1.0814kg (10mol) of p-Phenylenediamine (PDA) was dissolved in 14.9kg of N, N-Dimethylformamide (DMF), and after completely dissolving the solution by stirring at 40 ℃, 2.648kg (9mol) of biphenyltetracarboxylic dianhydride (BPDA) was added to fully react the solution to obtain a prepolymer solution 1 (molar ratio 0.9, solid content 20%). Prepolymer solution 2 (molar ratio 1.5, solids content 10%) was prepared in the same manner using 0.2704kg (2.5mol) PDA, 10.9kg DMF, and 1.1034kg (3.75mol) BPDA. Prepolymer solution 2 was added to prepolymer solution 1 at a rate of 2.5kg/h, and the mixture was thoroughly stirred at 40 ℃ to obtain the final polyamic acid solution (molar ratio 1.02, solid content 17.9%). The apparent viscosity of the final solution was measured to be 91 pas. After the solution was passed through a 2 μm glass fiber filter, the filter was free of foreign matter under irradiation of an ultraviolet fluorescent lamp. Filtering the polyamic acid solution by using filter materials with the particle size of 8 mu m and 1 mu m, and then performing vacuum defoaming to obtain polyamic acid film-forming stock solution.
The remaining steps were as in example 1.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, tensile strength of 419MPa, elongation at break of 17%, 5% thermal decomposition temperature of 601 ℃, glass transition temperature of 428 ℃ and thermal expansion coefficient of 3.4 ppm/K.
[ example 3 ]
1. Preparing stock solution: 2.0024kg (10mol) of ODA was dissolved in 27.2kg of DMAc, and after complete dissolution by stirring at 25 ℃, 2.7949kg (9.5mol) of BPDA was added to fully react to obtain a prepolymer solution 1 (molar ratio 0.95, solid content 15%). Prepolymer solution 2 (molar ratio 1.50, solids content 15%) was prepared in the same manner using 0.4445kg (2.22mol) ODA, 8.1kg DMAc, 0.9797kg (3.33mol) BPDA. Prepolymer solution 2 was added to prepolymer solution 1 at a rate of 9.5kg/h, and the mixture was thoroughly stirred at 25 ℃ to obtain the final polyamic acid solution (molar ratio 1.05, solid content 15%). The apparent viscosity of the final solution was measured to be 122 pas. After the solution was passed through a 2 μm glass fiber filter, the filter was free of foreign matter under irradiation of an ultraviolet fluorescent lamp. Filtering the polyamic acid solution by using a filter material with the diameter of 10 mu m and a filter material with the diameter of 1 mu m, and then performing vacuum defoaming to obtain polyamic acid film-forming stock solution.
The remaining steps were as in example 1.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, tensile strength of 328MPa, elongation at break of 29%, 5% thermal decomposition temperature of 561 ℃ close, glass transition temperature of 379 ℃ and thermal expansion coefficient of 34.3 ppm/K.
[ example 4 ]
1. Preparing stock solution: 1.0814kg (10mol) of p-Phenylenediamine (PDA) was dissolved in 8.7kg of N, N-Dimethylformamide (DMF), and after completely dissolving the solution by stirring at-10 ℃ C, 2.648kg (9mol) of biphenyltetracarboxylic dianhydride (BPDA) was added to fully react the solution to obtain a prepolymer solution 1 (molar ratio 0.9, solid content 30%). Prepolymer solution 2 (molar ratio 1.8, solids content 30%) was prepared in the same manner using 0.0636kg (0.588mol) of PDA, 0.874kg of DMF, and 0.311kg (1.058mol) of BPDA. Prepolymer solution 2 was added to prepolymer solution 1 at a rate of 2.4kg/h, and the mixture was thoroughly stirred at-10 ℃ to obtain the final polyamic acid solution (molar ratio 0.95, solid content 30%). The apparent viscosity of the final solution was measured to be 39 pas. After the solution was passed through a 2 μm glass fiber filter, no foreign matter was generated by irradiating the filter with an ultraviolet fluorescent lamp. Filtering the polyamic acid solution by a filter material with the diameter of 6 mu m and the diameter of 0.1 mu m, and then defoaming under reduced pressure to obtain polyamic acid film-forming stock solution.
The remaining steps were as in example 1.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, 410MPa of tensile strength, 12% of breaking elongation, 585 ℃ of thermal decomposition temperature of 5%, 394 ℃ of glass transition temperature and 7.9ppm/K of thermal expansion coefficient.
[ example 5 ]
1. Preparing stock solution: 2.0024kg (10mol) of ODA was dissolved in 27.8kg of N-methylpyrrolidone (NMP), stirred at 0 ℃ and completely dissolved, 1.0906kg (5mol) of PMDA was added thereto, and the mixture was sufficiently reacted to obtain a prepolymer solution 1 (molar ratio 0.5, solid content 10%). A prepolymer solution 2 (molar ratio 2.0, solid content 10%) was prepared in the same manner using 1.0012kg (5mol) ODA, 28.6416kg NMP, and 2.1812kg (10mol) PMDA. 31.82kg of the prepolymer solution 2 was added to the prepolymer solution 1 at a rate of 5.3kg/h, and sufficiently stirred at 0 ℃ to obtain a final polyamic acid solution (molar ratio 1.0, solid content 10%). The apparent viscosity of the final solution was measured to be 138 pas. After the solution was passed through a 2 μm glass fiber filter, no foreign matter was generated by irradiating the filter with an ultraviolet fluorescent lamp. Filtering the polyamic acid solution by a filter material with the particle size of 7 mu m and 0.4 mu m, and then carrying out vacuum defoamation to obtain polyamic acid film-forming stock solution.
The remaining steps were as in example 1.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, 341MPa of tensile strength, 26% of elongation at break, 5% of thermal decomposition temperature close to 573 ℃, 408 ℃ of glass transition temperature and 42.8ppm/K of thermal expansion coefficient.
[ example 6 ]
1. Preparing stock solution: 1.8022kg (9mol) of ODA was dissolved in 32.9kg of NMP, and after completely dissolving ODA by stirring at 10 ℃, 1.854kg (8.5mol) of PMDA was added to fully react to obtain a prepolymer solution 1 (molar ratio 0.944, solid content 10%). Prepolymer solution 2 (molar ratio 1.7, solids content 10%) was prepared in the same manner using 0.1081kg (1mol) of PDA, 5.4750kg of DMAc, 0.5002kg (1.7mol) of BPDA. 6.0833kg of the prepolymer solution 2 was added to the prepolymer solution 1 at a rate of 3kg/h, and the mixture was sufficiently stirred at 10 ℃ to obtain the final polyamic acid solution (molar ratio 1.02, solid content 10%). The apparent viscosity of the final solution was measured to be 26 pas. After the solution was passed through a 2 μm glass fiber filter, no foreign matter was generated by irradiating the filter with an ultraviolet fluorescent lamp. The polyamic acid solution was filtered through a filter of 9 μm and 0.7 μm and then subjected to vacuum defoaming to obtain a polyamic acid film-forming stock solution.
The remaining steps were as in example 1.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, 394MPa tensile strength, 21 percent elongation at break, 5 percent thermal decomposition temperature of 589 ℃, 410 ℃ glass transition temperature and 20.4ppm/K thermal expansion coefficient.
[ example 7 ]
1. Preparing stock solution: 2.0024kg (10mol) of ODA was dissolved in 44.1kg of DMSO, and after complete dissolution by stirring at 30 ℃, 2.9001kg (9mol) of 3,3 ', 4, 4' -benzophenonetetracarboxylic dianhydride (BTDA) was added to carry out a sufficient reaction to obtain prepolymer solution 1 (molar ratio 0.9, solid content 10%). Prepolymer solution 2 (molar ratio 1.5, solids 10%) was prepared in the same manner using 0.553kg (2.76mol) ODA, 17.0kg DMSO, and 1.3339kg (4.14mol) BTDA. The prepolymer solution 2 was added to the prepolymer solution 1 at a rate of 10kg/h, and sufficiently stirred at 30 ℃ to obtain a final polyamic acid solution (molar ratio 1.05, solid content 10%). The apparent viscosity of the final solution was measured to be 96 pas. After the solution was passed through a 2 μm glass fiber filter, the filter was free of foreign matter under irradiation of an ultraviolet fluorescent lamp. Filtering the polyamic acid solution by using a filter material with the particle size of 8 mu m and a filter material with the particle size of 0.3 mu m, and then performing vacuum defoaming to obtain polyamic acid film-forming stock solution.
The remaining steps were as in example 1.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, tensile strength of 337MPa, elongation at break of 20%, 5% thermal decomposition temperature close to 579 ℃, glass transition temperature of 403 ℃ and thermal expansion coefficient of 23.0 ppm/K.
[ example 8 ]
1. Preparing stock solution: after 1.802kg (9mol) of ODA was dissolved in 25.6kg of DMAc and stirred at 20 ℃ to be completely dissolved, 2.730kg (8.8mol) of 4, 4' -biphenylether dianhydride (ODPA) was added to the solution, and the solution A was obtained after the reaction was sufficiently carried out (molar ratio 0.98, solid content 15%). Prepolymer solution 2 (molar ratio 1.1, solids content 15%) was prepared in the same manner using 0.108kg (1mol) of PDA, 2.546kg of DMAc, and 0.341kg (1.1mol) of ODPA. Prepolymer solution 2 was added to prepolymer solution 1 at a rate of 3kg/h, and the mixture was thoroughly stirred at 20 ℃ to obtain the final polyamic acid solution (molar ratio 0.99, solid content 15%). The apparent viscosity of the final solution was measured to be 1.1 pas. After the solution was passed through a 2 μm glass fiber filter, the filter was free of foreign matter under irradiation of an ultraviolet fluorescent lamp. Filtering the polyamic acid solution by a filter material with the diameter of 6 mu m and the diameter of 0.2 mu m, and then defoaming under reduced pressure to obtain polyamic acid film-forming stock solution.
The remaining steps were as in example 1.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, tensile strength of 276MPa, elongation at break of 41%, 5% thermal decomposition temperature close to 544 ℃, glass transition temperature of 347 ℃ and thermal expansion coefficient of 46.6 ppm/K.
[ example 9 ]
1. Preparing stock solution: 1.8022kg (9mol) of ODA was dissolved in 67.810kg of DMAc, and after complete dissolution by stirring at-10 ℃, 1.7668kg (8.1mol) of PMDA was added to fully react to obtain a prepolymer solution 1 (molar ratio 0.9, solid content 5%). Prepolymer solution 2 (molar ratio 1.7, solids content 5%) was prepared in the same manner using 0.2002kg (1mol) ODA, 10.85kg DMAc, 0.3708kg (1.7mol) PMDA. Prepolymer solution 2 was added to prepolymer solution 1 at a rate of 3.8kg/h, and the mixture was thoroughly stirred at-10 ℃ to obtain the final polyamic acid solution (molar ratio 0.98, solid content 5%). The apparent viscosity of the final solution was measured to be 0.8 pas. After the solution was passed through a 2 μm glass fiber filter, the filter was free of foreign matter under irradiation of an ultraviolet fluorescent lamp. Filtering the polyamic acid solution by using a filter material with the particle size of 4 mu m and a filter material with the particle size of 0.1 mu m, and then performing vacuum defoaming to obtain polyamic acid film-forming stock solution.
The remaining steps were as in example 1.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, 323MPa of tensile strength, 19% of breaking elongation, nearly 566 ℃ of 5% thermal decomposition temperature, 381 ℃ of glass transition temperature and 41.4ppm/K of thermal expansion coefficient.
[ example 10 ]
1. Preparing stock solution: the stock solution preparation procedure of example 1 was followed.
2. Casting and film forming: the cast film formation procedure of example 1 was followed.
3. Pre-drying treatment: and (3) passing the polyamide acid wet film through a hot furnace at 100 ℃ in a nitrogen flowing atmosphere to obtain the self-supporting polyamide acid film.
4. Hot stretching: the self-supporting polyamic acid film was stretched 2.0 times in the machine direction and 1.5 times in the transverse direction at 200 ℃.
5. Thermal imidization: the stretched polyamic acid film is subjected to thermal imidization in 3 stages, and sequentially passes through a first temperature zone of 280 ℃, a second temperature zone of 330 ℃ and a third temperature zone of 380 ℃. And (6) slitting and rolling.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, tensile strength of 438MPa, elongation at break of 13%, thermal decomposition temperature of 5% of 606 ℃, glass transition temperature of 432 ℃ and thermal expansion coefficient of 5.7 ppm/K.
[ example 11 ]
1. Preparing stock solution: the stock solution preparation procedure of example 1 was followed.
2. Casting and film forming: the polyamic acid stock solution is subjected to doctor blade to control the thickness of a wet film to be 3000 mu m, and is cast on a smooth steel belt to form a film.
3. Pre-drying treatment: and (3) passing the polyamide acid wet film through a hot furnace at 150 ℃ in a nitrogen flowing atmosphere to obtain the self-supporting polyamide acid film.
The remaining steps were as in example 1.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, 429MPa of tensile strength, 12% of breaking elongation, 582 ℃ of thermal decomposition temperature, 409 ℃ of glass transition temperature and 11.8ppm/K of thermal expansion coefficient.
[ example 12 ]
1. Preparing stock solution: the stock solution preparation procedure of example 1 was followed.
2. Casting film forming and pre-baking treatment: the procedure of example 1 was followed.
3. Hot stretching: the self-supporting polyamic acid film was stretched at 300 ℃ in the machine direction by 1.5 times and in the transverse direction by 1.2 times.
The remaining steps were as in example 1.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, tensile strength of 404MPa, elongation at break of 16%, 5% thermal decomposition temperature of 592 ℃, glass transition temperature of 417 ℃ and thermal expansion coefficient of 6.6 ppm/K.
[ example 13 ]
1. Preparing stock solution: the stock solution preparation procedure of example 1 was followed.
2. Casting film forming, pre-baking treatment and hot stretching: the procedure of example 1 was followed.
3. Thermal imidization: the stretched polyamic acid film is subjected to thermal imidization in 3 stages, and sequentially passes through a first temperature zone of 250 ℃, a second temperature zone of 350 ℃ and a third temperature zone of 500 ℃. And (6) slitting and rolling.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, 462MPa of tensile strength, 8 percent of elongation at break, 615 percent of thermal decomposition temperature, 457 ℃ of glass transition temperature and 3.6ppm/K of coefficient of thermal expansion.
[ example 14 ]
1. Preparing stock solution: the stock solution preparation procedure of example 1 was followed.
2. Casting and film forming: the polyamic acid stock solution is subjected to doctor blade to control the thickness of a wet film to be 40 mu m, and is cast to form a film on a smooth steel belt.
3. Pre-drying treatment: and (3) under the flowing atmosphere of nitrogen, passing through a hot furnace at 50 ℃ to remove most of the solvent, thus obtaining the self-supporting polyamic acid film.
4. Hot stretching: the self-supporting polyamic acid film was stretched at 100 ℃ by 1.7 times in the machine direction and 1.1 times in the transverse direction.
The remaining steps were as in example 1.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, 402MPa of tensile strength, 17% of elongation at break, 593 ℃ of 5% of thermal decomposition temperature, 411 ℃ of glass transition temperature and 8.5ppm/K of thermal expansion coefficient.
[ example 15 ]
1. Preparing stock solution: the stock solution preparation procedure of example 1 was followed.
2. Casting and film forming: the polyamic acid stock solution is subjected to doctor blade to control the thickness of a wet film to be 1000 mu m, and is cast to form a film on a smooth steel belt.
3. Pre-drying treatment: and (3) under the flowing atmosphere of nitrogen, passing through a hot furnace at 100 ℃ to remove most of the solvent, thus obtaining the self-supporting polyamic acid film.
4. Hot stretching: the self-supporting polyamic acid film was subjected to 2.2-fold longitudinal stretching and 1.2-fold transverse stretching at 200 ℃ to obtain a stretched polyamic acid film.
5. Thermal imidization: the stretched polyamic acid film is subjected to multistage heating and thermal imidization to obtain a high-performance polyimide film, and the high-performance polyimide film is subjected to imidization at the temperature of 200 ℃ in a first temperature zone, 300 ℃ in a second temperature zone, 350 ℃ in a third temperature zone and 400 ℃ in a fourth temperature zone sequentially. And (6) slitting and rolling.
The PI film obtained by microscope observation has flat surface without defects, excellent thickness uniformity in test, 454MPa of tensile strength, 10% of elongation at break, 615 ℃ of thermal decomposition temperature of 5%, 447 ℃ of glass transition temperature and 2.7ppm/K of thermal expansion coefficient.
[ COMPARATIVE EXAMPLE 1 ]
1. Preparing stock solution: 1.001kg (5mol) of diphenyl ether diamine (ODA) was dissolved in 11.8kg of N, N-dimethylacetamide (DMAc), stirred at 25 ℃ and completely dissolved, and then 1.084kg (4.97mol) of pyromellitic dianhydride (PMDA) powder was added to fully react to obtain a polyamic acid solution, and the above experiment was repeated three times to measure apparent viscosities of the final solutions as 281Pa · s, 304Pa · s and 295Pa · s, respectively, and the batch-to-batch stability was inferior to that of example 1. After the solution was passed through a 2 μm glass fiber filter, the filter was exposed to a large amount of white foreign matter by an ultraviolet fluorescent lamp.
The remaining steps a PI film was prepared as in example 1.
And observing the surface of the obtained PI film by using a microscope to have a large number of defects. The tested film has poor thickness uniformity, the tensile strength of the film is 186MPa, the elongation at break of the film is 19 percent, the thermal decomposition temperature is 5 percent 579 ℃, the glass transition temperature is 388 ℃, and the thermal expansion coefficient is 42.2 ppm/K.
[ COMPARATIVE EXAMPLE 2 ]
1. Preparing stock solution: 1.001kg (5mol) diphenyl ether diamine (ODA) is dissolved in 11.8kg N, N-dimethylacetamide (DMAc), stirred under the protection of N2 at 25 ℃, after complete dissolution, 1.084kg (4.97mol) pyromellitic dianhydride (PMDA) is added in one portion, and after the addition is finished, the reaction is continued fully at 25 ℃. The test shows that the polyamic acid solution has apparent viscosity of 181 Pa.s at 25 deg.c, and after passing through 2 micron glass fiber filter screen, the filter screen has great amount of white foreign matter under the irradiation of ultraviolet fluorescent lamp.
The remaining steps a PI film was prepared as in example 1.
And observing the surface of the obtained PI film by using a microscope to have a large number of defects. The tested film has poor thickness uniformity and low performance, the tensile strength of the film is 230MPa, the elongation at break of the film is 9 percent, the thermal decomposition temperature is 5 percent 583 ℃, the glass transition temperature is 376 ℃, and the thermal expansion coefficient is 37.3 ppm/K.
[ COMPARATIVE EXAMPLE 3 ]
1. Preparing stock solution: 2.0024kg (10mol) of 4, 4' -diphenyletherdiamine were dissolved in 23.7kg of N, N-dimethylacetamide at room temperature2Stirring under protection until the monomer is completely dissolved, adding 2.1812kg (10mol) pyromellitic dianhydride powder, stirring at 0 deg.C, and stirring to obtain light yellow viscous solution with solid content of 7.0%.
2. Casting and film forming: the polyamic acid stock solution is subjected to doctor blade to control the thickness of a wet film to be 2000 mu m, and is cast to form a film on a smooth steel belt.
3. Pre-drying treatment: and (3) under the flowing atmosphere of nitrogen, passing through a hot furnace at the temperature of 150 ℃ to remove most of the solvent, thus obtaining the self-supporting polyamic acid film.
4. Hot stretching: the self-supporting polyamic acid film was subjected to 1.5-fold longitudinal stretching and 1.5-fold transverse stretching at 150 ℃ to obtain a stretched polyamic acid film.
5. Thermal imidization: the stretched polyamic acid film is subjected to multistage heating and thermal imidization to obtain a high-performance polyimide film, and the high-performance polyimide film is subjected to imidization at 300 ℃ in a first temperature zone, 350 ℃ in a second temperature zone and 400 ℃ in a third temperature zone sequentially. And (6) slitting and rolling.
And observing the surface of the obtained PI film by using a microscope to have a large number of defects. The tested film has poor thickness uniformity and low performance, the tensile strength of the obtained film is 249MPa, the elongation at break is 13 percent, the thermal decomposition temperature is 5 percent of 572 ℃, the glass transition temperature is 369 ℃, and the thermal expansion coefficient is 38 ppm/K.
Claims (9)
1. A preparation method of polyimide film is prepared by polyamide acid stock solution through film forming, hot stretching and hot imidization; the polyamide acid solution is characterized by comprising a mixed solution of a prepolymer solution 1 and a prepolymer solution 2; the prepolymer solution 1 is obtained by reacting a reactant comprising X moles of diamine and Y moles of dianhydride; the prepolymer solution 2 is obtained by reacting reactants comprising Z mol of diamine and K mol of dianhydride; the X, Y, Z, K satisfies: Y/X is more than or equal to 0.5 and less than or equal to 0.98, and K/Z is more than or equal to 1.02 and less than or equal to 2.0; the total molar ratio of dianhydride monomer to diamine monomer in the polyamic acid stock solution is 0.95-1.05: 1.
2. the method for preparing a polyimide film according to claim 1, comprising the steps of:
(1) preparation of a polyamic acid stock solution:
a) dissolving X mol of diamine in an organic solvent, and adding Y mol of dianhydride into a diamine solution to react to obtain a prepolymer solution 1;
b) dissolving diamine in Z mol in an organic solvent, and adding dianhydride in K mol into a diamine solution to react to obtain a prepolymer solution 2;
c) adding the prepolymer solution 2 into the prepolymer solution 1, uniformly mixing, and then filtering and defoaming to obtain a polyamide acid stock solution;
(2) casting and film forming: controlling the thickness of the polyamic acid stock solution obtained in the step (1) through a scraper, and carrying out tape casting on a smooth steel belt to obtain a polyamic acid wet film;
(3) pre-drying treatment: enabling the polyamic acid wet film obtained in the step (2) to pass through a constant-temperature heating furnace in an inert gas atmosphere to obtain a self-supporting polyamic acid film, wherein the pre-drying treatment temperature is 50-150 ℃;
(4) hot stretching: longitudinally stretching and transversely stretching the polyamic acid film obtained in the step (3) to obtain a stretched polyamic acid film, wherein the stretching temperature is 100-300 ℃;
(5) thermal imidization: and (3) performing thermal imidization on the stretched polyamide acid film obtained in the step (4) to obtain a high-performance polyimide film, wherein the thermal imidization temperature is 200-500 ℃.
3. The method for producing a polyimide film according to claim 1, wherein the polyamic acid is selected from the group consisting of structures represented by the general formula (1):
wherein Ar is1Is a tetravalent aromatic radical having at least one carbon-six membered ring, Ar2Is a divalent aromatic residue containing at least one carbon six-membered ring.
4. The method for preparing a polyimide film according to claim 2, wherein the addition rate of the prepolymer solution 2 in the step c) satisfies the following formula:
5. the method for preparing a polyimide film according to claim 2, wherein the organic solvent is at least one selected from the group consisting of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, and dimethylsulfoxide.
6. The method for preparing a polyimide film according to claim 2, wherein the reaction temperature in the step (1) is-10 to 40 ℃; the solid content of the polyamic acid stock solution is 5-30%.
7. The method for preparing a polyimide film according to claim 2, wherein the polyamic acid solution is filtered in a multistage manner with a precision of 0.1-10 μm.
8. The method for preparing a polyimide film according to claim 2, wherein the wet film thickness of the polyamic acid is controlled to be 40-3000 μm by a doctor blade in the casting film forming process.
9. The method for preparing a polyimide film according to claim 2, wherein the degassing process of the polyamic acid solution is vacuum degassing.
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| CN104327291A (en) * | 2014-09-23 | 2015-02-04 | 青岛文创科技有限公司 | Polyimide composite film preparation method |
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