CN105860074A - Polyimide precursor solution, preparation method thereof and method of utilizing polyimide precursor solution to prepare polyimide thin film - Google Patents

Abstract

A kind of polyimide precursor solution and its preparation method and the method for using it to prepare polyimide film, the present invention relates to polyimide precursor solution and its preparation method and the method for using it to prepare polyimide film . The present invention solves the problem that the existing polyimide precursor-polyamic acid aqueous solution preparation method and structural composition are difficult to produce polyimide films with high surface quality and continuous non-brittle cracking in casting equipment. A polyimide precursor solution is made of tertiary amine, water-based release agent, aromatic dianhydride, aromatic diamine, polar solvent and water; preparation method: weighing; under nitrogen atmosphere, certain temperature and stirring conditions , mix water, polar solvent and aromatic diamine, add the weighed aromatic dianhydride into the reaction liquid for reaction, add the weighed tertiary amine and water-based release agent to react under nitrogen atmosphere, certain temperature and stirring conditions , and finally cool down. Preparation of polyimide film: Prepare a self-supporting film, then cure and anneal.

Description

A kind of polyimide precursor solution and its preparation method and using it to prepare polyimide Amine film method

technical field

The invention relates to a polyimide precursor solution, a preparation method thereof and a method for preparing a polyimide film using the same.

Background technique

Polyimide is an aromatic heterocyclic polymer containing imide rings in repeating structural units. It is the highest heat-resistant polymer material used in the industrial field so far. With its excellent comprehensive performance, it can be used in films, resins, Fibers and separation membranes are widely used in aerospace, electronics and electrical fields. Traditional polyimides are usually made of aromatic tetracarboxylic anhydride and aromatic diamine in an aprotic polar solvent to form polyamic acid first, followed by imidization and dehydration to form polyimide.

Nowadays, with the development of the microelectronics field, polyimide films, especially colorless polyimides, are expected to be used as flexible transparent substrates to replace ITO glass, and have been widely used in flexible wearable devices and flexible display devices. Generally speaking, the polyimide precursor solution undergoes processes such as doctor blade coating, casting film formation and thermal imidization, and finally winds up to form a high-quality film. And use polar solvents, such as N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, etc., after the preparation of polyamic acid, in the process of casting volatilization and thermal imidization Both involve the waste gas caused by volatilization of a large amount of solvent in the drying tunnel and the pollution of waste liquid after settlement. Under normal circumstances, the hot air duct can be used to recover and repurify the solvent to a certain extent, but it is difficult to achieve 100% solvent recovery and 100% solvent separation and purification in the current technology. Conventional enterprises can only achieve more than 90% recovery, but it is difficult to produce high-quality polymers by recycling solvents; the remaining volatile matter will also have an impact on the atmosphere and water sources. From the perspective of environmental protection, polyimide films have become the most important An important factor of polluting chemical products, this problem has become an important problem in the field of polyimide membrane production.

Using water as a solvent for polyamic acid will undoubtedly greatly solve the problems in the preparation of polyimide, especially polyimide film. In this regard, there are bibliographical reports, such as "preparation of polyimide by water-soluble polyamic acid", insulating material 1981 (1): 34-42, after adding dianhydride/diamine to form polyamic acid in polar solvent Add ammonia or organic amine for neutralization, then add water to dilute to obtain a solution. However, a large amount of organic solvent is still introduced into the solution as an inducer of polymerization. Literature (High Performance Polymers, 2003 (15): 269-279.) reported that the dianhydride was hydrolyzed earlier, and then polymerized with diamine to form polyamic acid, which was precipitated in water, and the dry matter was washed repeatedly and thermally cyclized in a pressure bottle to obtain Polyimide powder. The process is extremely complicated, requires high equipment and is difficult to prepare in large quantities. At the same time, the obtained polyamic acid is insoluble in water, so it is difficult to apply to the polyimide film preparation process.

The water-soluble polyamic acid solutions involved in similar literature and patent reports are all researches on the structure of polyimide precursors. properties, mechanical properties, etc. There is no report about the self-supporting film formed by casting coating produced by polyimide precursor aqueous solution, and the continuous polyimide film formed by tension curing.

At the same time, the water-soluble polyimide precursor-polyamic acid solution involved in the literature and patents is catalyzed by a metal salt or amine salt to form a polyimide precursor, and the aqueous solution is heated to form a self-supporting precursor film. In the process of imidization, the water is basically volatilized (100°C), and the use of inorganic metal salts as catalysts will cause residues in the film; the use of a small amount of single-type amine salts will cause catalysts to come out from the surface of the formed self-supporting film On the one hand, the remaining voids will affect the surface quality of the final polyimide film, and on the other hand, the formation of voids will also affect the material properties of the film.

In addition, N,N-dimethylacetamide (boiling point 164°C) is usually selected as a solvent to form a polyimide precursor solution, and the temperature for casting out the solvent to form a self-supporting film is between 150°C and 250°C. The polyimide precursor-polyamic acid has a certain film strength, but in the process of imidization conversion (150°C-250°C), it will face the danger of a sharp decrease in molecular weight and a decrease in film strength. N,N-Dimethylacetamide is used as a solvent to avoid the embrittlement of the newly formed self-supporting film to a certain extent by containing the solvent at high temperature, reducing the risk of film breakage during high temperature stretching, and improving the continuous production efficiency of the molded body . The boiling point of water in the polyimide precursor aqueous solution is 100°C, and the temperature after removing water in the casting coating process is between 60°C and 120°C, which is lower than the imidization temperature, so it is formed without After the solvent self-supporting polyamic acid film undergoes stretch imidization reaction, due to the decrease of molecular weight (150-250°C), there is a great risk that the self-supporting film cannot withstand the traction tension of the system and breaks.

From the perspective of the preparation process of the above molded body, the different preparation methods and different catalyst types of the polyimide precursor-polyamic acid aqueous solution are not involved, and the self-supporting film (polyamic acid) of the polyimide cast film is not involved. film) and then experience the difficulty of film formation in the curing oven, as well as the surface quality and strength of the formed polyimide film.

Contents of the invention

The present invention will solve the problem that the existing polyimide precursor-polyamic acid aqueous solution preparation method and structural composition are difficult to realize the production of polyimide films with high surface quality and continuous non-brittle cracking in casting equipment, and provide A polyimide precursor solution, a preparation method thereof, and a method for preparing a polyimide film using the same.

A polyimide precursor solution is made of tertiary amine, aqueous release agent, aromatic dianhydride, aromatic diamine, polar solvent and water;

The molar ratio of the aromatic diamine to the tertiary amine is 1:(0.05～1.5); the mass ratio of the aromatic diamine to the aqueous release agent is 1:(0.01～1); the aromatic diamine The molar ratio to aromatic dianhydride is 1:(0.97～1.03); the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to water is 1:(2～10); the aromatic dianhydride and The mass ratio of the total mass of aromatic diamine to the polar solvent is 1:(0～10);

The aromatic diamines are 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, bis(3-aminophenoxy)benzophenone, p-phenylenediamine, m-phenylenediamine One or a mixture of diamines and 4,4'-diaminodiphenylsulfone;

The tertiary amine is a low-boiling tertiary amine or a mixture of a low-boiling tertiary amine and a high-boiling tertiary amine, and the molar ratio of the low-boiling tertiary amine to the high-boiling tertiary amine is 1:(0.01-100); the The low-boiling point tertiary amine has a boiling point below 150°C, and the molecular weight of the low-boiling point tertiary amine is 80g/mol-250g/mol; the high-boiling point tertiary amine is a tertiary amine with a boiling point between 150°C-295°C;

The polar solvent is one of N,N-dimethylacetamide, N,N-dimethylformamide, ethylene glycol and dimethyl sulfoxide or a mixture of several of them;

When the aromatic dianhydride is 3,3,4',4'-diphenyl ether tetracarboxylic dianhydride, 3,3,4',4'-disulfone tetracarboxylic dianhydride or 3,3, 4',4'-benzophenone tetracarboxylic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is:

The R ₁ is -O- or

_The R2 is

When the aromatic dianhydride is 3,3,4′,4′-biphenyltetracarboxylic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is:

The _R3 is

When the aromatic dianhydride is pyromellitic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is:

The R ₄ is

A kind of preparation method of polyimide precursor solution is to carry out according to the following steps:

1. Take tertiary amine, water-based release agent, aromatic dianhydride, aromatic diamine, polar solvent and water;

The molar ratio of the aromatic diamine to the tertiary amine is 1:(0.05～1.5); the mass ratio of the aromatic diamine to the aqueous release agent is 1:(0.01～1); the aromatic diamine The molar ratio to aromatic dianhydride is 1:(0.97～1.03); the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to water is 1:(2～10); the aromatic dianhydride and The mass ratio of the total mass of aromatic diamine to the polar solvent is 1:(0～10);

2. In a nitrogen atmosphere, at a temperature of 2°C to 10°C and under stirring conditions, add the water and polar solvent weighed in step 1 to the three-necked flask, and then add the aromatic diamine weighed in step 1 to obtain the reaction solution, the aromatic dianhydride weighed in step 1 was added to the reaction solution in three equal parts by mass, reacted for 1h to 5h, and then the reaction solution was heated to 20°C to 60°C, in a nitrogen atmosphere, the temperature was 20°C to 60°C ℃ and under stirring conditions, add the tertiary amine and water-based release agent weighed in step 1 to the reaction solution, stir and react for 3h to 5h, and finally reduce the temperature of the reaction solution to 2℃～10℃, and let it stand for 1h～10h. Obtain polyimide precursor solution;

The aromatic diamine described in step 1 is 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, bis(3-aminophenoxy)benzophenone, p-phenylenediamine , m-phenylenediamine and 4,4'-diaminodiphenyl sulfone or a mixture of several of them;

The tertiary amine described in step 1 is a low-boiling tertiary amine or a mixture of a low-boiling tertiary amine and a high-boiling tertiary amine, and the molar ratio of the low-boiling tertiary amine to the high-boiling tertiary amine is 1:(0.01～100); The low-boiling tertiary amine has a boiling point below 150°C, and the molecular weight of the low-boiling tertiary amine is 80g/mol-250g/mol; the high-boiling tertiary amine is a tertiary amine with a boiling point of 150°C-295°C;

The polar solvent described in step 1 is one or a mixture of several of N,N-dimethylacetamide, N,N-dimethylformamide, ethylene glycol and dimethyl sulfoxide;

When the aromatic dianhydride described in step 1 is 3,3,4',4'-diphenyl ether tetracarboxylic dianhydride, 3,3,4',4'-disulfone tetracarboxylic dianhydride or 3 , 3,4',4'-benzophenone tetracarboxylic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is:

The R ₁ is -O- or

_The R2 is

When the aromatic dianhydride described in step 1 is 3,3,4′,4′-biphenyltetracarboxylic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is:

The _R3 is

When the aromatic dianhydride described in step 1 is pyromellitic dianhydride, the repeating unit of polyamic acid in the described polyimide precursor solution is:

The R ₄ is

The method that utilizes a kind of polyimide precursor solution to prepare polyimide film is to carry out as follows:

1. Filter and degas the polyimide precursor solution, cast it on a stainless steel drum along the T-shaped slit, and then dry it at a temperature of 60 ° C to 180 ° C for 1 min to 50 min to obtain a self-supporting film ;

2. Peel the self-supporting film from the stainless steel drum and place it in a curing furnace for curing. First, heat it for 1min to 60min at a temperature of 150°C to 200°C, and then heat it at a temperature of 200°C to 250°C. , heating for 1min to 60min, then heating for 1min to 60min at a temperature of 250°C to 450°C, and finally annealing for about 1min to 20min at a temperature of 290°C to 310°C to obtain polyimide film;

And during the curing process, the self-supporting film is clamped by a clamp, so that the percentage change of the longitudinal length of the self-supporting film before and after curing is 5%-20%, and the percentage change of the transverse length is 10%-80%.

The beneficial effect of the present invention is: a kind of polyimide precursor solution provided by the present invention and its preparation method and the method for using it to prepare polyimide film can solve the problem of existing polyimide precursor-polyamic acid The preparation method and structural composition of the aqueous solution are difficult to realize the problem of producing high surface quality and continuous non-brittle polyimide films in casting equipment. According to the preparation method of the polyimide precursor solution, a combination of a low-proportion high-boiling-point polar solvent and various boiling-point tertiary amine compounds is used.

On the one hand, use the combination of high boiling point polar solvents (such as N,N-dimethylacetamide, N,N-dimethylformamide, etc.) and water to increase the overall boiling point of the solvent and avoid the formation of self-supporting polyimide The amine precursor film contains too little solvent (less than 20%) and has a low boiling point. Although the self-supporting film still undergoes high-temperature imidization (with or without stretching) process (150°C-250°C), it will There is a decrease in molecular weight and a decrease in strength, but the increase in solvent content and the increase in boiling point greatly improve the elongation and flexibility of the initial imidization (150°C-200°C), avoiding the high temperature due to external load The resulting danger of film breakage affects the continuous operation of the film.

On the other hand, the polyimide precursor solution preparation method uses a variety of boiling point tertiary amine complexes, so that when the solvent is cast out to form a self-supporting film, the precursor still contains a variety of boiling point tertiary amines. In the imidization process, the self-supporting film is poured into the curing furnace for processing, especially for the thermal imidization of the self-supporting film for continuous treatment, it is necessary to apply a certain axial external load to provide traction. After the water is basically volatilized ( <150°C), commonly used single tertiary amines also face the risk of volatilization at 150°C, and it is difficult to improve the low strength and low elongation after initial imidization (150°C-250°C) as a liquid residue. A variety of tertiary amines are used to provide a variety of removal temperatures and boiling points to achieve a certain liquid residue at temperatures above 150°C. And combined with high boiling point solvents, it can further ensure the continuous elongation and expansion coefficient of the film at the initial temperature of imidization, and greatly avoid the film damage at the initial imidization, especially under the action of traction The destruction of the film saves the cost of electricity and time for cooling the curing furnace, re-piercing the film, and heating up.

Unexpectedly, the combined use of various tertiary amines not only helps to improve the forming strength of the film at each stage, but also improves the surface quality of the film and reduces defects. After the single tertiary amine with a low boiling point and water volatilize, the polyimide precursor faces the double pressure of rapid imidization and solvent and catalyst detachment, which will seriously cause poor surface roughness of the film and surface left by volatilization. Pores, closed pores left by removing a large amount of water in a short period of imidization, etc., have a great influence on the surface quality of the film. Using the combination of low-boiling point and high-boiling point tertiary amines, unexpectedly obtained the continuous volatilization effect under different imidization conditions, so that the polyimide film formation process does not rely on external forces to provide self-leveling effect, greatly It solves the surface quality problem of the film. Especially for the thermal imidization operation of continuous film, not only the occurrence of wrinkles and voids is reduced, but also the flatness of the film is enhanced. And the polyimide precursor solution prepared by the present invention can also be used to form polyimide fibers.

The invention is used for a polyimide precursor solution, a preparation method thereof and a method for preparing a polyimide film by using the same.

Description of drawings

Fig. 1 is the polyimide film photo that embodiment four prepares;

Figure 2 is a photo of the polyimide film prepared in Comparative Experiment 1.

detailed description

Embodiment 1: A polyimide precursor solution in this embodiment is made of tertiary amine, aqueous release agent, aromatic dianhydride, aromatic diamine, polar solvent and water;

The molar ratio of the aromatic diamine to the tertiary amine is 1:(0.05～1.5); the mass ratio of the aromatic diamine to the aqueous release agent is 1:(0.01～1); the aromatic diamine The molar ratio to aromatic dianhydride is 1:(0.97～1.03); the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to water is 1:(2～10); the aromatic dianhydride and The mass ratio of the total mass of aromatic diamine to the polar solvent is 1:(0～10);

The aromatic diamines are 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, bis(3-aminophenoxy)benzophenone, p-phenylenediamine, m-phenylenediamine One or a mixture of diamines and 4,4'-diaminodiphenylsulfone;

The tertiary amine is a low-boiling tertiary amine or a mixture of a low-boiling tertiary amine and a high-boiling tertiary amine, and the molar ratio of the low-boiling tertiary amine to the high-boiling tertiary amine is 1:(0.01-100); the The low-boiling point tertiary amine has a boiling point below 150°C, and the molecular weight of the low-boiling point tertiary amine is 80g/mol-250g/mol; the high-boiling point tertiary amine is a tertiary amine with a boiling point between 150°C-295°C;

The polar solvent is one of N,N-dimethylacetamide, N,N-dimethylformamide, ethylene glycol and dimethyl sulfoxide or a mixture of several of them;

When the aromatic dianhydride is 3,3,4',4'-diphenyl ether tetracarboxylic dianhydride, 3,3,4',4'-disulfone tetracarboxylic dianhydride or 3,3, 4',4'-benzophenone tetracarboxylic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is:

The R ₁ is -O- or

_The R2 is

When the aromatic dianhydride is 3,3,4′,4′-biphenyltetracarboxylic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is:

The _R3 is

When the aromatic dianhydride is pyromellitic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is:

The R ₄ is

The beneficial effect of this embodiment is: a kind of polyimide precursor solution provided by this embodiment and its preparation method and the method for using it to prepare polyimide film can solve the problem of existing polyimide precursor - polyimide The preparation method and structural composition of the amic acid aqueous solution are difficult to realize the problem of producing high surface quality and continuous non-brittle polyimide films in tape casting equipment. According to the preparation method of the polyimide precursor solution, a combination of a low-proportion high-boiling-point polar solvent and various boiling-point tertiary amine compounds is used.

On the one hand, use the combination of high boiling point polar solvents (such as N,N-dimethylacetamide, N,N-dimethylformamide, etc.) and water to increase the overall boiling point of the solvent and avoid the formation of self-supporting polyimide The amine precursor film contains too little solvent (less than 20%) and has a low boiling point. Although the self-supporting film still undergoes high-temperature imidization (with or without stretching) process (150°C-250°C), it will There is a decrease in molecular weight and a decrease in strength, but the increase in solvent content and the increase in boiling point greatly improve the elongation and flexibility of the initial imidization (150°C-200°C), avoiding the high temperature due to external load The resulting danger of film breakage affects the continuous operation of the film.

On the other hand, the polyimide precursor solution preparation method uses a variety of boiling point tertiary amine complexes, so that when the solvent is cast out to form a self-supporting film, the precursor still contains a variety of boiling point tertiary amines. In the imidization process, the self-supporting film is poured into the curing furnace for processing, especially for the thermal imidization of the self-supporting film for continuous treatment, it is necessary to apply a certain axial external load to provide traction. After the water is basically volatilized ( <150°C), commonly used single tertiary amines also face the risk of volatilization at 150°C, and it is difficult to improve the low strength and low elongation after initial imidization (150°C-250°C) as a liquid residue. A variety of tertiary amines are used to provide a variety of removal temperatures and boiling points to achieve a certain liquid residue at temperatures above 150°C. And combined with high boiling point solvents, it can further ensure the continuous elongation and expansion coefficient of the film at the initial temperature of imidization, and greatly avoid the film damage at the initial imidization, especially under the action of traction The destruction of the film saves the cost of electricity and time for cooling the curing furnace, re-piercing the film, and heating up.

Unexpectedly, the combined use of various tertiary amines not only helps to improve the forming strength of the film at each stage, but also improves the surface quality of the film and reduces defects. After the single tertiary amine with a low boiling point and water volatilize, the polyimide precursor faces the double pressure of rapid imidization and solvent and catalyst detachment, which will seriously cause poor surface roughness of the film and surface left by volatilization. Pores, closed pores left by removing a large amount of water in a short period of imidization, etc., have a great influence on the surface quality of the film. Using the combination of low-boiling point and high-boiling point tertiary amines, unexpectedly obtained the continuous volatilization effect under different imidization conditions, so that the polyimide film formation process does not rely on external forces to provide self-leveling effect, greatly It solves the surface quality problem of the film. Especially for the thermal imidization operation of continuous film, not only the occurrence of wrinkles and voids is reduced, but also the flatness of the film is enhanced. And the polyimide precursor solution prepared in the specific embodiment can also be used to form polyimide fibers.

Specific embodiment two: the difference between this embodiment and specific embodiment one is: the low boiling point tertiary amine is triethylamine, dodecyl dimethyl tertiary amine, diethanol monoisopropanolamine and methyl One or a mixture of pyridines. Others are the same as in the first embodiment.

Specific embodiment three: the difference between this embodiment and specific embodiment one or two is that: the high-boiling point tertiary amine is one of tri-n-butylamine, triisopropanolamine and dimethylcarbamoyl chloride or a mixture of several of them. Others are the same as in the first or second embodiment.

Embodiment 4: This embodiment differs from Embodiments 1 to 3 in that the water-based release agent is a release agent or release agent that is miscible with water and does not precipitate when the temperature is less than 100°C. Formulations. Others are the same as the specific embodiments 1 to 3.

Embodiment 5: This embodiment differs from Embodiment 1 to Embodiment 4 in that the water-based release agent is RPLUS S02-004, Sepaluck RA715W, Sepaluck RA733W, NS-100 or SepaluckRA780W. Others are the same as the specific embodiments 1 to 4.

RPLUS S02-004 is produced by Klüber Company in Germany; Sepaluck RA715W, Sepaluck RA733W, NS-100 and Sepaluck RA780W are produced by Yamaichi Chemical Company in Japan.

Specific embodiment six: the difference between this embodiment and one of specific embodiments one to five is that: the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to the polar solvent is 1: (0-1.5); The molar ratio of the low-boiling tertiary amine to the high-boiling tertiary amine is 1:(0.5-100). Others are the same as those in Embodiments 1 to 5.

In this specific embodiment, the mass ratio of the total mass of aromatic dianhydride and aromatic diamine to the polar solvent can provide low solvent burden and maintain a good effect.

Specific embodiment seven: the preparation method of a kind of polyimide precursor solution described in this embodiment is to carry out according to the following steps:

1. Take tertiary amine, water-based release agent, aromatic dianhydride, aromatic diamine, polar solvent and water;

The molar ratio of the aromatic diamine to the tertiary amine is 1:(0.05～1.5); the mass ratio of the aromatic diamine to the aqueous release agent is 1:(0.01～1); the aromatic diamine The molar ratio to aromatic dianhydride is 1:(0.97～1.03); the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to water is 1:(2～10); the aromatic dianhydride and The mass ratio of the total mass of aromatic diamine to the polar solvent is 1:(0～10);

2. In a nitrogen atmosphere, at a temperature of 2°C to 10°C and under stirring conditions, add the water and polar solvent weighed in step 1 to the three-necked flask, and then add the aromatic diamine weighed in step 1 to obtain the reaction solution, the aromatic dianhydride weighed in step 1 was added to the reaction solution in three equal parts by mass, reacted for 1h to 5h, and then the reaction solution was heated to 20°C to 60°C, in a nitrogen atmosphere, the temperature was 20°C to 60°C ℃ and under stirring conditions, add the tertiary amine and water-based release agent weighed in step 1 to the reaction solution, stir and react for 3h to 5h, and finally reduce the temperature of the reaction solution to 2℃～10℃, and let it stand for 1h～10h. Obtain polyimide precursor solution;

The aromatic diamine described in step 1 is 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, bis(3-aminophenoxy)benzophenone, p-phenylenediamine , m-phenylenediamine and 4,4'-diaminodiphenyl sulfone or a mixture of several of them;

The tertiary amine described in step 1 is a low-boiling tertiary amine or a mixture of a low-boiling tertiary amine and a high-boiling tertiary amine, and the molar ratio of the low-boiling tertiary amine to the high-boiling tertiary amine is 1:(0.01～100); The low-boiling tertiary amine has a boiling point below 150°C, and the molecular weight of the low-boiling tertiary amine is 80g/mol-250g/mol; the high-boiling tertiary amine is a tertiary amine with a boiling point of 150°C-295°C;

The polar solvent described in step 1 is one or a mixture of several of N,N-dimethylacetamide, N,N-dimethylformamide, ethylene glycol and dimethyl sulfoxide;

When the aromatic dianhydride described in step 1 is 3,3,4',4'-diphenyl ether tetracarboxylic dianhydride, 3,3,4',4'-disulfone tetracarboxylic dianhydride or 3 , 3,4',4'-benzophenone tetracarboxylic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is:

The R ₁ is -O- or

_The R2 is

When the aromatic dianhydride described in step 1 is 3,3,4′,4′-biphenyltetracarboxylic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is:

The _R3 is

When the aromatic dianhydride described in step 1 is pyromellitic dianhydride, the repeating unit of polyamic acid in the described polyimide precursor solution is:

The R ₄ is

Embodiment 8: The difference between this embodiment and Embodiment 7 is that the low-boiling tertiary amine described in step 1 is triethylamine, dodecyldimethyl tertiary amine, diethanol monoisopropanolamine and picoline or a mixture of several of them. Others are the same as in the seventh embodiment.

Specific embodiment nine: the difference between this embodiment and one of specific embodiment seven or eight is: the high boiling point tertiary amine described in step one is tri-n-butylamine, triisopropanolamine and dimethylcarbamoyl chloride one or a mixture of several of them. Others are the same as the seventh or eighth specific embodiment.

Embodiment 10: The difference between this embodiment and one of Embodiments 7 to 9 is that the water-based release agent described in step 1 is a release agent that is miscible with water and does not precipitate when the temperature is less than 100°C. Molding agent or release agent. Others are the same as the seventh to ninth embodiments.

Embodiment 11: The difference between this embodiment and embodiment 7 to 11 is that the water-based release agent described in step 1 is RPLUS S02-004, Sepaluck RA715W, Sepaluck RA733W, NS-100 or Sepaluck RA780W . Others are the same as Embodiments 7 to 10.

RPLUS S02-004 is produced by Klüber Company in Germany; Sepaluck RA715W, Sepaluck RA733W, NS-100 and Sepaluck RA780W are produced by Yamaichi Chemical Company in Japan.

Embodiment 12: The difference between this embodiment and Embodiment 7 to 11 is that the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine described in step 1 to the polar solvent is 1:( 0～1.5); The molar ratio of the low boiling point tertiary amine and the high boiling point tertiary amine described in step one is 1:(0.5～100). Others are the same as Embodiments 7 to 11.

In this specific embodiment, the mass ratio of the total mass of aromatic dianhydride and aromatic diamine to the polar solvent can provide low solvent burden and maintain a good effect.

Specific Embodiment Thirteen: The method for preparing a polyimide film using a polyimide precursor solution in this embodiment is specifically carried out in the following steps:

1. Filter and degas the polyimide precursor solution, cast it on a stainless steel drum along the T-shaped slit, and then dry it at a temperature of 60 ° C to 180 ° C for 1 min to 50 min to obtain a self-supporting film ;

2. Peel the self-supporting film from the stainless steel drum and place it in a curing furnace for curing. First, heat it for 1min to 60min at a temperature of 150°C to 200°C, and then heat it at a temperature of 200°C to 250°C. , heating for 1min to 60min, then heating for 1min to 60min at a temperature of 250°C to 450°C, and finally annealing for about 1min to 20min at a temperature of 290°C to 310°C to obtain polyimide film;

And during the curing process, the self-supporting film is clamped by a clamp, so that the percentage change of the longitudinal length of the self-supporting film before and after curing is 5%-20%, and the percentage change of the transverse length is 10%-80%.

The polyimide film of this embodiment can be obtained by imidating the polyamic acid which is a precursor. In addition, workers' raw materials, reaction conditions, etc. may be used in its manufacture. In addition, inorganic or organic fillers can be added according to functional needs.

Next, the self-supporting film is peeled off from the surface of the substrate to carry out the curing process, which can be achieved by immersing in an aqueous solution, applying additional tension, and the like.

The polyimide film is a polyimide film obtained from a polyimide precursor solution. As a polyimide film, it can be used as liquid crystal alignment film, porous polyimide film for fuel cells, separation membrane, PCB board single layer, double layer, multilayer, R-F, HDI film substrate, insulating film for wire and cable, High temperature film etc.

The beneficial effect of this embodiment is: a kind of polyimide precursor solution provided by this embodiment and its preparation method and the method for using it to prepare polyimide film can solve the problem of existing polyimide precursor - polyimide The preparation method and structural composition of the amic acid aqueous solution are difficult to realize the problem of producing high surface quality and continuous non-brittle polyimide films in tape casting equipment. According to the preparation method of the polyimide precursor solution, a combination of a low-proportion high-boiling-point polar solvent and various boiling-point tertiary amine compounds is used.

On the one hand, use the combination of high boiling point polar solvents (such as N,N-dimethylacetamide, N,N-dimethylformamide, etc.) and water to increase the overall boiling point of the solvent and avoid the formation of self-supporting polyimide The amine precursor film contains too little solvent (less than 20%) and has a low boiling point. Although the self-supporting film still undergoes high-temperature imidization (with or without stretching) process (150°C-250°C), it will There is a decrease in molecular weight and a decrease in strength, but the increase in solvent content and the increase in boiling point greatly improve the elongation and flexibility of the initial imidization (150°C-200°C), avoiding the high temperature due to external load The resulting danger of film breakage affects the continuous operation of the film.

On the other hand, the polyimide precursor solution preparation method uses a variety of boiling point tertiary amine complexes, so that when the solvent is cast out to form a self-supporting film, the precursor still contains a variety of boiling point tertiary amines. In the imidization process, the self-supporting film is poured into the curing furnace for processing, especially for the thermal imidization of the self-supporting film for continuous treatment, it is necessary to apply a certain axial external load to provide traction. After the water is basically volatilized ( <150°C), commonly used single tertiary amines also face the risk of volatilization at 150°C, and it is difficult to improve the low strength and low elongation after initial imidization (150°C-250°C) as a liquid residue. A variety of tertiary amines are used to provide a variety of removal temperatures and boiling points to achieve a certain liquid residue at temperatures above 150°C. And combined with high boiling point solvents, it can further ensure the continuous elongation and expansion coefficient of the film at the initial temperature of imidization, and greatly avoid the film damage at the initial imidization, especially under the action of traction The destruction of the film saves the cost of electricity and time for cooling the curing furnace, re-piercing the film, and heating up.

Unexpectedly, the combined use of various tertiary amines not only helps to improve the forming strength of the film at each stage, but also improves the surface quality of the film and reduces defects. After the single tertiary amine with a low boiling point and water volatilize, the polyimide precursor faces the double pressure of rapid imidization and solvent and catalyst detachment, which will seriously cause poor surface roughness of the film and surface left by volatilization. Pores, closed pores left by removing a large amount of water in a short period of imidization, etc., have a great influence on the surface quality of the film. Using the combination of low-boiling point and high-boiling point tertiary amines, unexpectedly obtained the continuous volatilization effect under different imidization conditions, so that the polyimide film formation process does not rely on external forces to provide self-leveling effect, greatly It solves the surface quality problem of the film. Especially for the thermal imidization operation of continuous film, not only the occurrence of wrinkles and voids is reduced, but also the flatness of the film is enhanced. And the polyimide precursor solution prepared in the specific embodiment can also be used to form polyimide fibers.

Embodiment 14: This embodiment is different from Embodiment 13 in that: in step 1, dry at a temperature of 80° C. to 160° C. for 10 minutes to 30 minutes. Others are the same as in the thirteenth embodiment.

The beneficial effects of this embodiment are:

Adopt the following examples to verify the beneficial effects of the present invention:

Embodiment one:

A polyimide precursor solution is made of tertiary amine, aqueous release agent, aromatic dianhydride, aromatic diamine, polar solvent and water;

The molar ratio of the aromatic diamine to the tertiary amine is 1:0.05; the mass ratio of the aromatic diamine to the aqueous release agent is 1:0.01; the molar ratio of the aromatic diamine to the aromatic dianhydride is 1:1; the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to water is 1:8; the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to the polar solvent is 1: 1;

Described aromatic diamine is p-phenylenediamine;

Described tertiary amine is diethanol monoisopropanolamine;

The polar solvent is N,N-dimethylacetamide; the water-based release agent is NS-100 produced by Japan Yamaichi Chemical Company;

The aromatic dianhydride is 3,3,4′,4′-biphenyltetracarboxylic dianhydride, and the repeating unit of polyamic acid in the polyimide precursor solution is:

The preparation method of above-mentioned a kind of polyimide precursor solution is to carry out as follows:

1. Take 8.16g diethanol monoisopropanolamine (0.05mol), 1.08g NS-100, 294.22g 3,3,4',4'-biphenyltetracarboxylic dianhydride (1mol), 108.14g p-phenylene Diamine (1mol), 402.36g N,N-dimethylacetamide and 3218.88g water;

2. In a nitrogen atmosphere, at a temperature of 5°C and under stirring conditions, add 3218.88g of water and 402.36g of N,N-dimethylacetamide to a three-necked flask, and then add 108.14g of p-phenylenediamine (1mol) to obtain a reaction Liquid, 294.22g 3,3,4',4'-biphenyltetracarboxylic dianhydride (1mol) was added to the reaction liquid in three times according to the mass average, and reacted for 5h, then the reaction liquid was heated to 20 ° C, under nitrogen Under the condition of atmosphere and temperature of 20°C and stirring, add 8.16g of diethanol monoisopropanolamine (0.05mol) and 1.08g of NS-100 to the reaction solution, stir for 5 hours, and finally lower the temperature of the reaction solution to 5°C. Leave standstill 10h, obtain polyimide precursor solution;

The method that utilizes above-mentioned a kind of polyimide precursor solution to prepare polyimide film is to carry out as follows:

1. Filter and degas the polyimide precursor solution, cast it onto a stainless steel drum along the T-shaped slit, and then dry it at 120°C for 10 minutes to obtain a self-supporting film;

2. Peel the self-supporting film from the stainless steel drum and place it in a curing furnace for curing. First, heat it for 3 minutes at a temperature of 150°C, then heat it for 3 minutes at a temperature of 250°C, and then heat it at a temperature of 250°C. Heating at 400°C for 70s, and finally annealing at 300°C for about 1 min to obtain a polyimide film;

And during the curing process, the self-supporting film is clamped by a clamp, so that the percentage change of the longitudinal length of the self-supporting film before and after curing is 10%, and the percentage change of the transverse length is 50%.

The thickness of the polyimide film prepared in this embodiment is 25 microns.

Embodiment two:

A polyimide precursor solution is made of tertiary amine, aqueous release agent, aromatic dianhydride, aromatic diamine, polar solvent and water;

The molar ratio of the aromatic diamine to the tertiary amine is 1:0.05; the mass ratio of the aromatic diamine to the aqueous release agent is 1:0.01; the molar ratio of the aromatic diamine to the aromatic dianhydride is 1:1; the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to water is 1:8; the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to the polar solvent is 1: 1;

The aromatic diamine is 4,4'-diaminodiphenyl ether;

Described tertiary amine is diethanol monoisopropanolamine;

The polar solvent is N,N-dimethylacetamide;

The water-based release agent is NS-100 produced by Japan Yamaichi Chemical Company;

When the aromatic dianhydride is pyromellitic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is:

The preparation method of above-mentioned a kind of polyimide precursor solution is to carry out as follows:

1. Take 8.16g of diethanol monoisopropanolamine (0.05mol), 2.00g of NS-100, 218.12g of pyromellitic dianhydride (1mol), 200.24g of 4,4'-diaminodiphenyl Ether (1mol), 418.36g of N,N-dimethylacetamide and 3346.88g of water;

2. In a nitrogen atmosphere, at a temperature of 5°C and under stirring conditions, add 3346.88 g of water and 418.36 g of N,N-dimethylacetamide into the three-necked flask, and then add 200.24 g of 4,4 '-Diaminodiphenyl ether (1mol) to obtain a reaction solution, 218.12g of pyromellitic dianhydride (1mol) was added to the reaction solution in three equal parts by mass, reacted for 2h, and then the reaction solution was heated to 20°C , under a nitrogen atmosphere, a temperature of 20°C and stirring conditions, add 8.16g of diethanol monoisopropanolamine (0.05mol) and 2.00g of NS-100 to the reaction solution, stir the reaction for 5h, and finally reduce the temperature of the reaction solution to Decrease to 5°C and let it stand for 10 hours to obtain a polyimide precursor solution;

The method that utilizes above-mentioned a kind of polyimide precursor solution to prepare polyimide film is to carry out as follows:

1. Filter and degas the polyimide precursor solution, cast it onto a stainless steel drum along the T-shaped slit, and then dry it at 120°C for 10 minutes to obtain a self-supporting film;

2. Peel the self-supporting film from the stainless steel drum and place it in a curing furnace for curing. First, heat it for 3 minutes at a temperature of 150°C, then heat it for 3 minutes at a temperature of 250°C, and then heat it at a temperature of 250°C. Heating at 400°C for 70s, and finally annealing at 300°C for about 1 min to obtain a polyimide film;

And during the curing process, the self-supporting film is clamped by a clamp, so that the percentage change of the longitudinal length of the self-supporting film before and after curing is 10%, and the percentage change of the transverse length is 50%.

The thickness of the polyimide film prepared in this embodiment is 25 microns.

Embodiment three:

A polyimide precursor solution is made of tertiary amine, aqueous release agent, aromatic dianhydride, aromatic diamine and water;

The molar ratio of the aromatic diamine to the tertiary amine is 1:0.05; the mass ratio of the aromatic diamine to the aqueous release agent is 1:0.01; the molar ratio of the aromatic diamine to the aromatic dianhydride is 1:1; the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to water is 1:9;

Described aromatic diamine is p-phenylenediamine;

The tertiary amine is a mixture of a low-boiling tertiary amine and a high-boiling tertiary amine, and the molar ratio of the low-boiling tertiary amine to the high-boiling tertiary amine is 1:1;

Described low boiling point tertiary amine is diethanol monoisopropanolamine;

Described high boiling point tertiary amine is dimethylcarbamoyl chloride;

The water-based release agent is NS-100 produced by Japan Yamaichi Chemical Company;

The aromatic dianhydride is 3,3,4′,4′-biphenyltetracarboxylic dianhydride, and the repeating unit of polyamic acid in the polyimide precursor solution is:

The preparation method of above-mentioned a kind of polyimide precursor solution is to carry out as follows:

1. Take 4.08g of diethanol monoisopropanolamine (0.025mol), 2.69g of dimethylcarbamoyl chloride (0.025mol), 1.08g of NS-100, 294.22g of 3,3,4',4 '-biphenyltetracarboxylic dianhydride (1mol), 108.14g of p-phenylenediamine (1mol) and 3621.24g of water;

2. In a nitrogen atmosphere, at a temperature of 5°C and under stirring conditions, add 3621.24g of water to the three-necked flask, then add 108.14g of p-phenylenediamine (1mol) to obtain a reaction solution, and 294.22g of 3,3 , 4',4'-biphenyltetracarboxylic dianhydride (1mol) was added to the reaction liquid in three times according to the mass average, reacted for 5h, and then the reaction liquid was heated to 20°C, in a nitrogen atmosphere, the temperature was 20°C and stirred Under conditions, add 4.08g of diethanol monoisopropanolamine (0.025mol), 2.69g of dimethylcarbamoyl chloride (0.025mol) and 1.08g of NS-100 to the reaction solution, stir the reaction for 5h, and finally The temperature of the reaction solution was lowered to 5° C., and allowed to stand for 10 hours to obtain a polyimide precursor solution;

The method that utilizes above-mentioned a kind of polyimide precursor solution to prepare polyimide film is to carry out as follows:

1. Filter and degas the polyimide precursor solution, cast it onto a stainless steel drum along the T-shaped slit, and then dry it at 120°C for 10 minutes to obtain a self-supporting film;

2. Peel the self-supporting film from the stainless steel drum and place it in a curing furnace for curing. First, heat it for 3 minutes at a temperature of 150°C, then heat it for 3 minutes at a temperature of 250°C, and then heat it at a temperature of 250°C. Heating at 400°C for 70s, and finally annealing at 300°C for about 1 min to obtain a polyimide film;

And during the curing process, the self-supporting film is clamped by a clamp, so that the percentage change of the longitudinal length of the self-supporting film before and after curing is 10%, and the percentage change of the transverse length is 50%.

The thickness of the polyimide film prepared in this embodiment is 25 microns.

Embodiment four:

A polyimide precursor solution is made of tertiary amine, aqueous release agent, aromatic dianhydride, aromatic diamine, polar solvent and water;

The molar ratio of the aromatic diamine to the tertiary amine is 1:0.05; the mass ratio of the aromatic diamine to the aqueous release agent is 1:0.01; the molar ratio of the aromatic diamine to the aromatic dianhydride is 1:1; the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to water is 1:8; the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to the polar solvent is 1: 1;

Described aromatic diamine is p-phenylenediamine;

The tertiary amine is a mixture of a low-boiling tertiary amine and a high-boiling tertiary amine, and the molar ratio of the low-boiling tertiary amine to the high-boiling tertiary amine is 1:1;

Described low boiling point tertiary amine is diethanol monoisopropanolamine;

Described high boiling point tertiary amine is dimethylcarbamoyl chloride;

The polar solvent is N,N-dimethylacetamide;

The water-based release agent is NS-100 produced by Japan Yamaichi Chemical Company;

The aromatic dianhydride is 3,3,4′,4′-biphenyltetracarboxylic dianhydride, and the repeating unit of polyamic acid in the polyimide precursor solution is:

The preparation method of above-mentioned a kind of polyimide precursor solution is to carry out as follows:

1. Take 4.08g of diethanol monoisopropanolamine (0.025mol), 2.69g of dimethylcarbamoyl chloride (0.025mol), 1.08g of NS-100, 294.22g of 3,3,4',4 '-biphenyltetracarboxylic dianhydride (1mol), 108.14g of p-phenylenediamine (1mol), 402.36g of N,N-dimethylacetamide and 3218.88g of water;

2. In a nitrogen atmosphere, at a temperature of 5°C and under stirring conditions, add 3218.88g of water and 402.36g of N,N-dimethylacetamide into the three-necked flask, and then add 108.14g of p-phenylenediamine (1mol ), to obtain the reaction solution, 294.22g of 3,3,4',4'-biphenyltetracarboxylic dianhydride (1mol) was added to the reaction solution in three times by mass average, reacted for 5h, and then the reaction solution was heated to 20 DEG C, under nitrogen atmosphere, temperature is 20 DEG C and under stirring condition, add the diethanol monoisopropanolamine (0.025mol) of 4.08g, the dimethylcarbamoyl chloride (0.025mol) of 2.69g and 1.08g of NS-100, stirred and reacted for 5h, and finally lowered the temperature of the reaction solution to 5°C, and stood still for 10h to obtain a polyimide precursor solution;

The method that utilizes above-mentioned a kind of polyimide precursor solution to prepare polyimide film is to carry out as follows:

1. Filter and degas the polyimide precursor solution, cast it onto a stainless steel drum along the T-shaped slit, and then dry it at 120°C for 10 minutes to obtain a self-supporting film;

2. Peel the self-supporting film from the stainless steel drum and place it in a curing furnace for curing. First, heat it for 3 minutes at a temperature of 150°C, then heat it for 3 minutes at a temperature of 250°C, and then heat it at a temperature of 250°C. Heating at 400°C for 70s, and finally annealing at 300°C for about 1 min to obtain a polyimide film;

And during the curing process, the self-supporting film is clamped by a clamp, so that the percentage change of the longitudinal length of the self-supporting film before and after curing is 10%, and the percentage change of the transverse length is 50%.

The thickness of the polyimide film prepared in this embodiment is 25 microns.

Embodiment five:

A polyimide precursor solution is made of tertiary amine, aqueous release agent, aromatic dianhydride, aromatic diamine, polar solvent and water;

The molar ratio of the aromatic diamine to the tertiary amine is 1:0.05; the mass ratio of the aromatic diamine to the aqueous release agent is 1:0.01; the molar ratio of the aromatic diamine to the aromatic dianhydride is 1:1; the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to water is 1:8; the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to the polar solvent is 1: 1;

Described aromatic diamine is p-phenylenediamine;

The tertiary amine is a mixture of a low-boiling tertiary amine and a high-boiling tertiary amine, and the molar ratio of the low-boiling tertiary amine to the high-boiling tertiary amine is 1:1;

Described low boiling point tertiary amine is diethanol monoisopropanolamine;

Described high boiling point tertiary amine is dimethylcarbamoyl chloride;

The polar solvent is N,N-dimethylacetamide;

The water-based release agent is NS-100 produced by Japan Yamaichi Chemical Company;

The aromatic dianhydride is 3,3,4′,4′-biphenyltetracarboxylic dianhydride, and the repeating unit of polyamic acid in the polyimide precursor solution is:

The preparation method of above-mentioned a kind of polyimide precursor solution is to carry out as follows:

1. Take 4.08g of diethanol monoisopropanolamine (0.025mol), 2.69g of dimethylcarbamoyl chloride (0.025mol) and 1.08g of NS-100, 294.22g of 3,3,4',4 '-biphenyltetracarboxylic dianhydride (1mol), 108.14g of p-phenylenediamine (1mol), 402.36g of N,N-dimethylacetamide and 3218.88g of water;

2. In a nitrogen atmosphere, at a temperature of 5°C and under stirring conditions, add 3218.88g of water and 402.36g of N,N-dimethylacetamide into the three-necked flask, and then add 108.14g of p-phenylenediamine (1mol ), to obtain the reaction solution, 294.22g of 3,3,4',4'-biphenyltetracarboxylic dianhydride (1mol) was added to the reaction solution in three times by mass average, reacted for 5h, and then the reaction solution was heated to 20 DEG C, under nitrogen atmosphere, temperature is 20 DEG C and under stirring condition, add the diethanol monoisopropanolamine (0.025mol) of 4.08g, the dimethylcarbamoyl chloride (0.025mol) of 2.69g and 1.08g of NS-100, stirred and reacted for 5h, and finally lowered the temperature of the reaction solution to 5°C, and stood still for 10h to obtain a polyimide precursor solution;

The method that utilizes above-mentioned a kind of polyimide precursor solution to prepare polyimide film is to carry out as follows:

1. Filter and degas the polyimide precursor solution, cast it onto a stainless steel drum along the T-shaped slit, and then dry it at 120°C for 10 minutes to obtain a self-supporting film;

2. Peel the self-supporting film from the stainless steel drum and place it in a curing furnace for curing. First, heat it for 3 minutes at a temperature of 150°C, then heat it for 3 minutes at a temperature of 250°C, and then heat it at a temperature of 250°C. Heating at 400°C for 70s, and finally annealing at 300°C for about 1 min to obtain a polyimide film;

And during the curing process, the self-supporting film is clamped by a clamp, so that the percentage change of the longitudinal length of the self-supporting film before and after curing is 5%, and the percentage change of the transverse length is 20%.

The thickness of the polyimide film prepared in this embodiment is 25 microns.

Comparative experiment one:

A polyimide precursor solution is made of tertiary amine, aromatic dianhydride, aromatic diamine and water;

The molar ratio of the aromatic diamine to the tertiary amine is 1:0.05; the molar ratio of the aromatic diamine to the aromatic dianhydride is 1:1; the total mass of the aromatic dianhydride and the aromatic diamine to water The mass ratio is 1:9;

Described aromatic diamine is p-phenylenediamine;

Described tertiary amine is triethylamine;

The aromatic dianhydride is 3,3,4′,4′-biphenyltetracarboxylic dianhydride, and the repeating unit of polyamic acid in the polyimide precursor solution is:

The preparation method of above-mentioned a kind of polyimide precursor solution is to carry out as follows:

1. Take 5.06g of triethylamine (0.05mol), 294.22g of 3,3,4',4'-biphenyltetracarboxylic dianhydride (1mol), 108.14g of p-phenylenediamine (1mol) and 3621.24g of water;

2. In a nitrogen atmosphere, at a temperature of 5°C and under stirring conditions, add 3621.24g of water to the three-necked flask, then add 108.14g of p-phenylenediamine (1mol) to obtain a reaction solution, and 294.22g of 3,3 , 4',4'-biphenyltetracarboxylic dianhydride (1mol) was added to the reaction liquid in three times according to the mass average, reacted for 5h, and then the reaction liquid was heated to 20°C, in a nitrogen atmosphere, the temperature was 20°C and stirred Under certain conditions, 5.06 g of triethylamine (0.05 mol) was added to the reaction solution, stirred and reacted for 5 hours, and finally the temperature of the reaction solution was lowered to 5° C., and allowed to stand for 10 hours to obtain a polyimide precursor solution;

The method that utilizes above-mentioned a kind of polyimide precursor solution to prepare polyimide film is to carry out as follows:

1. Filter and degas the polyimide precursor solution, cast it onto a stainless steel drum along the T-shaped slit, and then dry it at 120°C for 10 minutes to obtain a self-supporting film;

2. The self-supporting film is peeled off from the stainless steel drum and placed in a curing furnace, and cured at a temperature of 150 ° C. During the curing process, the self-supporting film is clamped by a clamp, and the self-supporting film breaks under traction and heating. The longitudinal elongation at break is 5%, and the obtained polyimide is thin.

In comparative experiment 1, a continuous polyimide film could not be obtained.

Comparative experiment two:

A polyimide precursor solution is made of tertiary amine, aqueous release agent, aromatic dianhydride, aromatic diamine and water;

The molar ratio of the aromatic diamine to the tertiary amine is 1:0.05; the mass ratio of the aromatic diamine to the aqueous release agent is 1:0.01; the molar ratio of the aromatic diamine to the aromatic dianhydride is 1:1; the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to water is 1:9;

Described aromatic diamine is p-phenylenediamine;

Described tertiary amine is diethanol monoisopropanolamine;

The water-based release agent is NS-100 produced by Japan Yamaichi Chemical Company;

The aromatic dianhydride is 3,3,4′,4′-biphenyltetracarboxylic dianhydride, and the repeating unit of the polyamic acid blocked in the polyimide precursor solution is:

The preparation method of above-mentioned a kind of polyimide precursor solution is to carry out as follows:

1. Take 8.16g of diethanol monoisopropanolamine (0.05mol), 1.08g of NS-100, 294.22g of 3,3,4',4'-biphenyltetracarboxylic dianhydride (1mol), 108.14 g of p-phenylenediamine (1mol) and 3621.24g of water;

2. In a nitrogen atmosphere, at a temperature of 5°C and under stirring conditions, add 3621.24g of water to the three-necked flask, then add 108.14g of p-phenylenediamine (1mol) to obtain a reaction solution, and 294.22g of 3,3 , 4',4'-biphenyltetracarboxylic dianhydride (1mol) was added to the reaction liquid in three times according to the mass average, reacted for 5h, and then the reaction liquid was heated to 20°C, in a nitrogen atmosphere, the temperature was 20°C and stirred Under certain conditions, 8.16 g of diethanol monoisopropanolamine (0.05 mol) and 1.08 g of NS-100 were added to the reaction liquid, and the reaction was stirred for 5 hours. Finally, the temperature of the reaction liquid was lowered to 5° C. and allowed to stand for 10 hours to obtain poly Imide precursor solution;

The method that utilizes above-mentioned a kind of polyimide precursor solution to prepare polyimide film is to carry out as follows:

1. Filter and degas the polyimide precursor solution, cast it onto a stainless steel drum along the T-shaped slit, and then dry it at 120°C for 10 minutes to obtain a self-supporting film;

2. Peel the self-supporting film from the stainless steel drum and place it in a curing oven for curing. During the curing process, use a clamp to hold the self-supporting film, and cure it at a temperature of 150°C for 3 minutes, and then place it in a curing oven at a temperature of 250°C. Under certain conditions, the self-supporting film breaks during the traction heating process, and the longitudinal elongation at breakage is 8%, and the polyimide film is obtained.

In comparative experiment 2, a continuous polyimide film could not be obtained.

The surface quality of the polyimide films prepared in Examples 1 and 5 and the polyimide films prepared in Comparative Experiments 1 and 2 were evaluated by means of surface microcracks, surface smoothness, and surface air bubbles.

①. Micro-cracks on the surface:

Evaluate the micro-cracks on the polyimide film surface, the evaluation criteria are as follows:

A: No microcracks were found on the surface of the film;

B: on the surface of the film (less than 5% of the film surface area), it can be confirmed that there are surface microcracks;

C: on the surface of the film (greater than 5%, less than 10% of the film surface area), it can be confirmed that there are surface microcracks;

D: The presence of surface microcracks can be confirmed on the surface of the film (more than 10% of the film surface area).

②. Surface roughness:

Evaluate the surface smoothness of polyimide film, evaluation standard is as follows:

A: Use a spiral micrometer to test the thickness of the film, take the data of 5 test points in different areas (each area accounts for no less than 15% of the surface area per unit width), and obtain the maximum value, minimum value and minus value of the data. Remove the average value, and the ratio to the average value is within ±5%;

B: Use a spiral micrometer to test the thickness of the film, take data from 5 test points in different regions (each region accounts for no less than 15% of the surface area per unit width), and obtain the maximum value, minimum value minus the value of the data. Remove the average value, and the ratio to the average value is within ±10%;

C: Use a spiral micrometer to test the thickness of the film, take the data of 5 test points in different regions (each region accounts for no less than 15% of the surface area per unit width), and obtain the maximum value, minimum value minus the value of the data. Remove the average value, and the ratio to the average value is within ±15%;

D: Use a spiral micrometer to test the thickness of the film, take the data of 5 test points in different regions (each region accounts for no less than 15% of the surface area per unit width), and obtain the maximum value, minimum value minus the value of the data. The average value is removed, and the ratio to the average value is outside ±15%.

③. Surface bubbles:

Evaluate the surface air bubble that polyimide film surface exists, evaluation standard is as follows:

A: there is no surface bubble on the surface of the polyimide film;

B: the surface bubble that exists on polyimide film surface (10cm * 10cm) is more than 1 but less than 5;

C: the surface bubbles that exist on the polyimide film surface (10cm * 10cm) are more than 5 but less than 50;

D: there are more than 50 surface bubbles on the polyimide film surface (10cm * 10cm).

The 5% thermal weight loss temperature was measured for the polyimide films prepared in Examples 1 and 5 and the polyimide films prepared in Comparative Experiments 1 and 2: the test was performed using a thermogravimetric analyzer (TGA). Heating rate: 10°C/min; Test atmosphere: air.

The polyimide films prepared in Examples 1 and 5 and the polyimide films prepared in Comparative Experiments 1 and 2 were tested for 800% carbon residue rate: the test was performed using a thermogravimetric analyzer (TGA). Heating rate: 10°C/min; test atmosphere: nitrogen.

The glass transition temperature of the polyimide films prepared in Examples 1 and 5 and the polyimide films prepared in Comparative Experiments 1 and 2 was tested: a dynamic thermomechanical analyzer (DMA) was used for the test. Heating rate: 5°C/min; Test atmosphere: air.

Mechanical tests were performed on the polyimide films prepared in Examples 1 and 5 and the polyimide films prepared in Comparative Experiments 1 and 2, using the ASTM D882 standard for testing.

Table 1 is the surface quality and film-forming properties of polyimide films, and Table 2 is the performance of continuously prepared polyimide films. It can be seen from Table 1 that the continuous polyimide film preparation cannot be completed in the comparative experiment, irreversible self-supporting film fracture occurred during the operation of the curing oven, the longitudinal elongation did not meet the standard, and the transverse elongation operation has not yet been performed. In addition, the comparative experiments are far lower than the examples in terms of surface quality, including surface flatness, surface microcracks and surface air bubbles. Among them, in Embodiment 4 and Embodiment 5, due to the use of multiple amine catalysts combined with high boiling point solvents, the formed film has a more excellent surface smoothness than Embodiments 1 to 3.

It can be seen from Table 2 that the continuous thin film preparation cannot be completed in the comparative experiment. Therefore, the mechanical properties (ND) of the films could not be tested, and only some samples were tested for thermal properties. It can be seen from the test that the thermal performance data of the comparative tests are all lower than those of the examples, because the thermal performance of the polyimide material is affected to some extent due to the lack of proper elongation orientation. Comparing Example 5 and Example 4, it is also because there is no suitable in-plane bidirectional elongation orientation, which affects both the thermal and mechanical properties of the film, especially the mechanical properties.

Fig. 1 is the photo of the polyimide film prepared in Example 4; Fig. 2 is the photo of the polyimide film prepared in Comparative Experiment 1. It can be seen from the figure that the surface quality of the polyimide film obtained in the comparison test is not good, and at the same time, because the film is brittle and broken midway, it cannot be stretched transversely, resulting in wrinkles on the film surface and fracture lines at the end.

Table 1 Surface quality and film-forming properties of polyimide films

Table 2 Properties of polyimide films prepared continuously

Claims (10)

1. A polyimide precursor solution is characterized in that a polyimide precursor solution is made of tertiary amine, aqueous release agent, aromatic dianhydride, aromatic diamine, polar solvent and water; The molar ratio of the aromatic diamine to the tertiary amine is 1:(0.05～1.5); the mass ratio of the aromatic diamine to the aqueous release agent is 1:(0.01～1); the aromatic diamine The molar ratio to aromatic dianhydride is 1:(0.97～1.03); the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to water is 1:(2～10); the aromatic dianhydride and The mass ratio of the total mass of aromatic diamine to the polar solvent is 1:(0～10); The aromatic diamines are 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, bis(3-aminophenoxy)benzophenone, p-phenylenediamine, m-phenylenediamine One or a mixture of diamines and 4,4'-diaminodiphenylsulfone; The tertiary amine is a low-boiling tertiary amine or a mixture of a low-boiling tertiary amine and a high-boiling tertiary amine, and the molar ratio of the low-boiling tertiary amine to the high-boiling tertiary amine is 1:(0.01-100); the The low-boiling point tertiary amine has a boiling point below 150°C, and the molecular weight of the low-boiling point tertiary amine is 80g/mol-250g/mol; the high-boiling point tertiary amine is a tertiary amine with a boiling point between 150°C-295°C; The polar solvent is one of N,N-dimethylacetamide, N,N-dimethylformamide, ethylene glycol and dimethyl sulfoxide or a mixture of several of them; When the aromatic dianhydride is 3,3,4',4'-diphenyl ether tetracarboxylic dianhydride, 3,3,4',4'-disulfone tetracarboxylic dianhydride or 3,3, 4',4'-benzophenone tetracarboxylic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is: The R ₁ is -O- or _The R2 is When the aromatic dianhydride is 3,3,4′,4′-biphenyltetracarboxylic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is: The _R3 is When the aromatic dianhydride is pyromellitic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is: The R ₄ is 2. a kind of polyimide precursor solution according to claim 1, it is characterized in that described low boiling point tertiary amine is triethylamine, dodecyl dimethyl tertiary amine, diethanol monoisopropyl One or a mixture of alcohol amines and picoline. 3. a kind of polyimide precursor solution according to claim 1, it is characterized in that described high boiling point tertiary amine is one in tri-n-butylamine, triisopropanolamine and dimethylcarbamoyl chloride species or a mixture of several of them. 4. A kind of polyimide precursor solution according to claim 1, it is characterized in that described aqueous release agent is the release agent that can be miscible with water under the condition that temperature is less than 100 ℃, and does not separate out or release agent. 5. the preparation method of a kind of polyimide precursor solution as claimed in claim 1 is characterized in that the preparation method of a kind of polyimide precursor solution is to carry out according to the following steps: 1. Take tertiary amine, water-based release agent, aromatic dianhydride, aromatic diamine, polar solvent and water; The molar ratio of the aromatic diamine to the tertiary amine is 1:(0.05～1.5); the mass ratio of the aromatic diamine to the aqueous release agent is 1:(0.01～1); the aromatic diamine The molar ratio to aromatic dianhydride is 1:(0.97～1.03); the mass ratio of the total mass of the aromatic dianhydride and aromatic diamine to water is 1:(2～10); the aromatic dianhydride and The mass ratio of the total mass of aromatic diamine to the polar solvent is 1:(0～10); 2. In a nitrogen atmosphere, at a temperature of 2°C to 10°C and under stirring conditions, add the water and polar solvent weighed in step 1 to the three-necked flask, and then add the aromatic diamine weighed in step 1 to obtain the reaction solution, the aromatic dianhydride weighed in step 1 was added to the reaction solution in three equal parts by mass, reacted for 1h to 5h, and then the reaction solution was heated to 20°C to 60°C, in a nitrogen atmosphere, the temperature was 20°C to 60°C ℃ and under stirring conditions, add the tertiary amine and water-based release agent weighed in step 1 to the reaction solution, stir and react for 3h to 5h, and finally reduce the temperature of the reaction solution to 2℃～10℃, and let it stand for 1h～10h. Obtain polyimide precursor solution; The aromatic diamine described in step 1 is 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, bis(3-aminophenoxy)benzophenone, p-phenylenediamine , m-phenylenediamine and 4,4'-diaminodiphenyl sulfone or a mixture of several of them; The tertiary amine described in step 1 is a low-boiling tertiary amine or a mixture of a low-boiling tertiary amine and a high-boiling tertiary amine, and the molar ratio of the low-boiling tertiary amine to the high-boiling tertiary amine is 1:(0.01～100); The low-boiling tertiary amine has a boiling point below 150°C, and the molecular weight of the low-boiling tertiary amine is 80g/mol-250g/mol; the high-boiling tertiary amine is a tertiary amine with a boiling point of 150°C-295°C; The polar solvent described in step 1 is one or a mixture of several of N,N-dimethylacetamide, N,N-dimethylformamide, ethylene glycol and dimethyl sulfoxide; When the aromatic dianhydride described in step 1 is 3,3,4',4'-diphenyl ether tetracarboxylic dianhydride, 3,3,4',4'-disulfone tetracarboxylic dianhydride or 3 , 3,4',4'-benzophenone tetracarboxylic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is: The R ₁ is -O- or _The R2 is When the aromatic dianhydride described in step 1 is 3,3,4′,4′-biphenyltetracarboxylic dianhydride, the repeating unit of polyamic acid in the polyimide precursor solution is: The _R3 is When the aromatic dianhydride described in step 1 is pyromellitic dianhydride, the repeating unit of polyamic acid in the described polyimide precursor solution is: The R ₄ is 6. the preparation method of a kind of polyimide precursor solution according to claim 5 is characterized in that the low boiling point tertiary amine described in step 1 is triethylamine, dodecyl dimethyl tertiary amine , diethanol monoisopropanolamine and picoline or a mixture of several of them. 7. the preparation method of a kind of polyimide precursor solution according to claim 5 is characterized in that the high boiling point tertiary amine described in step 1 is tri-n-butylamine, triisopropanolamine and dimethylamine One or a mixture of several of the methanoyl chlorides. 8. The preparation method of a kind of polyimide precursor solution according to claim 5, it is characterized in that the water-based release agent described in step 1 can be miscible with water under the condition that the temperature is less than 100 ℃, and Mold release or release agent that does not precipitate. 9. utilize a kind of polyimide precursor solution described in claim 1 to prepare the method for polyimide film, it is characterized in that utilizing a kind of polyimide precursor solution to prepare the method for polyimide film is to press Follow these steps: 1. Filter and degas the polyimide precursor solution, cast it on a stainless steel drum along the T-shaped slit, and then dry it at a temperature of 60 ° C to 180 ° C for 1 min to 50 min to obtain a self-supporting film ; 2. Peel the self-supporting film from the stainless steel drum and place it in a curing furnace for curing. First, heat it for 1min to 60min at a temperature of 150°C to 200°C, and then heat it at a temperature of 200°C to 250°C. , heating for 1min to 60min, then heating for 1min to 60min at a temperature of 250°C to 450°C, and finally annealing for about 1min to 20min at a temperature of 290°C to 310°C to obtain polyimide film; And during the curing process, the self-supporting film is clamped by a clamp, so that the percentage change of the longitudinal length of the self-supporting film before and after curing is 5%-20%, and the percentage change of the transverse length is 10%-80%. 10 . The method for preparing a polyimide film by using a polyimide precursor solution according to claim 9 , wherein in step 1, drying is performed at a temperature of 80° C. to 160° C. for 10 minutes to 30 minutes. 11 .