CN112552514B

CN112552514B - Polyimide precursor, polyimide film and preparation method of polyimide film

Info

Publication number: CN112552514B
Application number: CN202011454171.3A
Authority: CN
Inventors: 肖桂林; 付华; 阮敏; 鲁丽平; 朱双全
Original assignee: Hubei Dinglong Co ltd; Wuhan Rouxian Technology Co ltd
Current assignee: Hubei Dinglong Co ltd; Wuhan Rouxian Technology Co ltd
Priority date: 2020-12-10
Filing date: 2020-12-10
Publication date: 2023-05-16
Anticipated expiration: 2040-12-10
Also published as: CN112552514A

Abstract

The invention relates to a polyimide precursor, a polyimide film and a preparation method thereof, and in particular relates to a polyimide precursor which is formed by reacting diamine A, dianhydride B and an additive C under certain reaction conditions. Wherein the mass of the fluorine-containing dianhydride or the fluorine-containing dianhydride is not more than 5% of the mass of the total dianhydride and diamine, the transmittance of the polyamide acid slurry is 65-67%, when the thickness of the coating film is 10 mu m, the uniformity of the coating film is within 2%, the yellow index of the polyimide film is 21-22, the thermal expansion coefficient at 50-200 ℃ is 2-3ppm/K, and the wavelength transmittance at 400nm is 83-86%.

Description

Polyimide precursor, polyimide film and preparation method of polyimide film

Technical Field

The invention relates to the technical field of high polymer materials, in particular to a polyimide precursor, a polyimide film and a preparation method thereof.

Background

Polyimide is used as a special engineering plastic with an imine ring and a rigid chain structure in a main chain, has very excellent mechanical property, heat resistance, flame retardance, solvent resistance, radiation resistance and electrical property, and is widely applied to a series of high and new technical fields such as aerospace, photoelectricity, automobiles and the like.

Along with the increase of demands of people for flexible display wearing and foldable display equipment, polyimide film materials with advantages in various aspects become important materials of attention, and high-temperature resistant polyimide films are substrate materials of attention in the preparation process of AMOLED panels, and the high temperature resistance is due to the fact that a plurality of working procedures in the panel manufacturing process need to be subjected to high temperature, such as laser crystallization, the common crystallization temperature reaches 450 ℃, and the improvement of the transparency of the films can improve the sensitivity of fingerprint identification under a screen, and the realization of camera technology under the screen can be conveniently realized, so that the screen occupation ratio can be further improved, and the real comprehensive screen can be realized.

In polyimide monomers, a large aromatic monomer containing a conjugated structure is generally used as a main component to achieve a high-temperature-resistant process without deteriorating the performance of the film, but the film obtained by the monomer is generally dark in color, has a yellowness index of 30 or more and has a transmittance of 83% or less at a wavelength of 400 nm. The common means for improving transparency in the prior art are: the method breaks through large conjugated structures such as adding aliphatic monomers into monomers or replacing fluorine-free aromatic monomers with fluorine-containing aromatic monomers, but both methods are based on the premise of reducing the temperature resistance of the film, and at present, although some structures can achieve the temperature resistance of about 400 ℃, the requirements of panel manufacturers are not met in the process of being applied to the panels.

Disclosure of Invention

The invention designs a novel method for preparing polyimide precursor, which improves the transparency of the polyimide precursor prepared by the method and improves the coating uniformity, thereby improving the heat resistance, yellow index and transparency of the polyimide film.

The first aspect of the present invention provides a polyimide precursor, wherein the polyimide precursor is prepared by reacting dianhydride a, diamine B, and an additive C, at least one of the dianhydride a and the diamine B is a fluorine-containing dianhydride or a fluorine-containing diamine, the molar amount of the fluorine-containing dianhydride or the fluorine-containing dianhydride is not more than 5% of the molar amount of the total dianhydride and the diamine, and the additive C includes one of a radical scavenger, a hindered phenol antioxidant, and a phosphite antioxidant.

Further, the dianhydride a is selected from one or more combinations of 3,3', 4' -biphenyl tetracarboxylic dianhydride (BPDA), 3, 4-diphenyl ketone tetracarboxylic dianhydride (BTDA), pyromellitic dianhydride (PMDA), 4-Oxydiphthalic Dianhydride (ODPA), 2' -bis (3, 4-dicarboxylic acid) hexafluoropropane dianhydride (6 FDA).

Preferably, the dianhydride A is a combination of 3,3', 4' -biphenyl tetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA).

Further, the diamine B is selected from one or more of 4,4' -diaminodiphenyl ether (ODA), 2-bis [4- (4-aminophenoxy) phenyl ] propane (BAPP), p-Phenylenediamine (PDA), 4' -diamino-2, 2' -bistrifluoromethyl biphenyl (TFMB).

Preferably, the diamine B is a combination of 4,4' -diaminodiphenyl ether (ODA), p-Phenylenediamine (PDA), and 4,4' -diamino-2, 2' -bistrifluoromethyl biphenyl (TFMB).

Further, the additive C is one of sodium ascorbate, hydroquinone, pentaerythritol tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], N' -bis- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexamethylenediamine or tris (2, 4-di-tert-butylphenyl) phosphite, wherein the dosage of the additive C accounts for 0.01 to 0.1 percent of the molar percentage of the total diamine dosage.

Preferably, the additive C is sodium ascorbate.

In a second aspect, the present invention provides a polyimide film obtained by imidizing the polyimide precursor.

Wherein, the thermal expansion coefficient of the polyimide film is 2-3ppm/K, the yellow index is 21-22, and the transmittance at 400nm wavelength is 83-86%.

The third aspect of the present invention provides a method for preparing a polyimide film, comprising the steps of:

s1: dissolving diamine B in an organic solvent D to obtain a solution in which diamine B is dissolved;

s2: adding an additive C into the solution with diamine B dissolved in the step S1, wherein the dosage of the additive C accounts for 0.01-0.1% of the molar percentage of the total diamine B;

s3: adding dianhydride A into the dissolved diamine B and additive C for 1h in multiple times, reacting at 40 ℃ for 6-10h after each dianhydride A addition until all dianhydride A is completely added, and obtaining polyamic acid solution after polymerization, wherein the molar ratio of dianhydride to diamine of the polyamic acid solution is 0.95-1.10;

s4: and (3) coating and curing the polyamic acid solution obtained in the step (S3) to obtain the polyimide film. The invention has the beneficial effects that: the molar quantity of fluorine-containing dianhydride or fluorine-containing diamine in the invention is not more than 5% of the total dianhydride and dianhydride molar quantity, and a certain quantity of additive is added in the process of preparing polyamide acid, so that amine group oxidation in the process of preparing polyamide acid is reduced, the terminal groups of polyamide acid can uniformly participate in the reaction in the synthesis process, the transparency of slurry is improved, the coating uniformity is improved due to the reduction of the oxidized quantity of amine groups, the CTE of the prepared polyimide film is 2-3ppm/K, the yellow index is 21-22, the transparency is 83-86%, and the polyamide acid solution can be applied to the fields of flexible circuit boards, flexible AMOLED substrates, solar panels and the like, and is particularly suitable for flexible AMOLED substrates when a proper monomer structure is selected. The polyimide film obtained by curing the polyamic acid solution obtained by the invention has excellent coating uniformity, excellent dimensional stability and high transparency, and is very suitable for AMOLED substrate or cover plate materials.

Detailed Description

The polyimide precursor is prepared by reacting dianhydride A, diamine B and an additive C, wherein at least one of the reactants dianhydride A and diamine B is fluorine-containing dianhydride or fluorine-containing diamine, specifically, a certain amount of diamine B is taken to be dissolved in an organic solvent D to obtain a solution in which the diamine B is dissolved, the additive C is added into the solution, then the dianhydride A is added into the components of the dissolved diamine B and the additive C for multiple times, the adding time is 1-5h, the reaction is carried out for 6-10h at 40 ℃ after each dianhydride A is added until all the dianhydride A is completely added, and the polyamic acid solution is obtained after the polymerization is finished, thus obtaining the polyimide precursor.

In the method for synthesizing the polyamic acid solution, firstly, diamine B monomer and dianhydride A monomer are added into a solvent, or dianhydride A monomer and diamine B monomer are also added, or part of diamine B monomer and part of dianhydride A monomer are added to ensure that the amine is excessive, and after part of diamine B monomer is added for dissolution, dianhydride A monomer is added to ensure that the total diamine B and dianhydride A monomer are close to the equimolar ratio; or adding part of diamine B monomer, adding part of dianhydride A monomer to make anhydride excessive, adding dianhydride A monomer after adding part of diamine B monomer to dissolve so as to make total diamine B and dianhydride A monomer approach equimolar ratio; the molar ratio of dianhydride A to diamine B is preferably 0.95 to 1.10.

The dianhydride A in the polyimide precursor of the present invention is selected from the group consisting of 1, 1-bis (3, 4-dicarboxyphenyl) ethane dianhydride, 2,3,5, 6-pyridinetetracarboxylic dianhydride, bicyclo [3.1.1 ] hept-2-ene tetracarboxylic dianhydride, 1-bis (2, 3-dicarboxyphenyl) ethane dianhydride, 3,4,9, 10-perylenetetracarboxylic dianhydride, bicyclo [2.2.2 ] octanetetracarboxylic dianhydride, bis (3, 4-dicarboxyphenyl) methane dianhydride, N, N '-bis [5,5' -hexafluoropropane-2, 2-diyl-bis (2-hydroxyphenyl) ] bis (3, 4-dicarboxybenzamide), adamantane tetracarboxylic dianhydride, bis (2, 3-dicarboxyphenyl) methane dianhydride, bis (3, 4-dicarboxyphenyl) sulfone dianhydride, 1,2,3, 4-cyclopentane tetracarboxylic dianhydride, cyclohexane tetracarboxylic dianhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 1,2,5, 6-naphthalene tetracarboxylic dianhydride, bicyclo [2.2.1 ] heptane tetracarboxylic dianhydride, 2-bis (2, 3-dicarboxyphenyl) hexafluoropropane dianhydride, 2,3,6, 7-naphthalene tetracarboxylic dianhydride, bicyclo [3.3.1 ] tetracarboxylic dianhydride, 3',4,4' -biphenyltetracarboxylic dianhydride, 3, 4-diphenylmethanone tetracarboxylic dianhydride, pyromellitic dianhydride, 4-oxydiphthalic dianhydride, 2,2' -bis (3, 4-dicarboxylic acid) hexafluoropropane dianhydride, and one or more combinations of the following structural dianhydrides;

in view of avoiding a decrease in CTE value of the polyimide film after introduction of fluorine atoms, the dianhydride a is selected to have an aromatic structure, and thus one or more combinations of 3,3', 4' -biphenyl tetracarboxylic dianhydride, 3, 4-diphenylketone tetracarboxylic dianhydride, pyromellitic dianhydride, 4-oxydiphthalic dianhydride, 2' -bis (3, 4-dicarboxylic acid) hexafluoropropane dianhydride are preferable among the dianhydrides a.

Further, since the biphenyl structure and the monocyclic aromatic structure molecule have high rigidity, the CTE value of the polyimide film can be further reduced, and therefore, from the viewpoint of improving the rigidity of the molecule, it is further preferable that the dianhydride a is a combination of 3,3', 4' -biphenyl tetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA).

The diamine B in the polyimide precursor of the present invention is selected from m-phenylenediamine, 1, 5-naphthalenediamine, 2, 6-naphthalenediamine, bis (3-amino-4-hydroxyphenyl) hexafluoropropane, bis (3-amino-4-hydroxyphenyl) sulfone, bis (3-amino-4-hydroxyphenyl) propane, bis (3-amino-4-hydroxyphenyl) methane, bis (3-amino-4-hydroxyphenyl) ether, bis (3-amino-4-hydroxy) biphenyl, bis (3-amino-4-hydroxyphenyl) fluorene, 1, 4-bis (4-aminophenoxy) benzene, 2 '-dimethyl-4, 4' -diaminobiphenyl, 2 '-diethyl-4, 4' -diaminobiphenyl, 3 '-dimethyl-4, 4' -diaminobiphenyl, 3 '-diethyl-4, 4' -diaminobiphenyl, 2',3,3' -tetramethyl-4, 4 '-diaminobiphenyl, 3',4 '-tetramethyl-4, 4' -diaminobiphenyl, 2 '-bis (trifluoromethyl) -5,5' -dihydroxybenzidine, 3,4 '-diaminodiphenyl ether, 3,4' -diaminodiphenyl methane, 4,4 '-diaminodiphenylmethane, 3,4' -diaminodiphenylsulfone, 4 '-diaminodiphenylsulfone, 3,4' -diaminodiphenylsulfide, 4 '-diaminodiphenylsulfide, 1, 4-bis (4-aminophenoxy) benzene, bis (4-aminophenoxyphenyl) sulfone, bis (3-aminophenoxyphenyl) sulfone, bis (4-aminophenoxy) biphenyl, bis {4- (4-aminophenoxy) phenyl } ether, 3, 5-diaminobenzoic acid, 3-carboxy-4, 4' -diaminodiphenylether, 2-bis [4- (4-aminophenoxy) phenyl ] propane, p-phenylenediamine, 4 '-diamino-2, 2' -bistrifluoromethyl biphenyl, and diamines of the structure;

in view of the high heat resistance of the polyimide film, the diamine B is preferably a diamine having an aromatic structure, and thus the diamine B is preferably one or a combination of 4,4' -diaminodiphenyl ether, 2-bis [4- (4-aminophenoxy) phenyl ] propane, p-phenylenediamine, and 4,4' -diamino-2, 2' -bistrifluoromethyl biphenyl.

Since the diamine structure contains a single aromatic ring or the CTE value can be effectively reduced when two amino groups are para-position to each other, the diamine B is more preferably a combination of 4,4' -diaminodiphenyl ether and p-phenylenediamine for this purpose, and 4,4' -diamino-2, 2' -bistrifluoromethyl biphenyl is preferable among the diamines B for the purpose of improving the transparency of the film.

The dianhydride A and the diamine B of the polyimide precursor in the invention at least comprise one fluorine-containing dianhydride or fluorine-containing diamine, wherein the weight of the fluorine-containing dianhydride or the fluorine-containing diamine is not more than 5% of the total mass of the dianhydride and the diamine monomer, the fluorine-containing structure is preferably fluorine-containing diamine, preferably 4,4 '-diamino-2, 2' -bistrifluoromethyl biphenyl, and the molar amount of the 4,4 '-diamino-2, 2' -bistrifluoromethyl biphenyl is preferably 1.5% of the total mass of the dianhydride and the diamine monomer.

The additive C in the polyimide precursor comprises one of a free radical scavenger, a hindered phenol antioxidant and a phosphite antioxidant, and the specific additive C is one of sodium ascorbate, hydroquinone, tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, N, N' -bis- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexamethylenediamine and tri (2, 4-di-tert-butylphenyl) phosphite;

in terms of lowering the CTE value and improving the light transmittance of the slurry, additive C is preferably one of sodium ascorbate, N' -bis- (3, 5-di-t-butyl-4-hydroxyphenyl) propionyl) hexamethylenediamine.

In order to further inhibit oxidation of the diamine monomer, so that the whole polycondensation process is more uniform, the additive C is further preferably sodium ascorbate.

The amount of the additive C is 0.001-0.1%, preferably 0.01-0.1%, and more preferably 0.05% of the total diamine B;

as the most preferred embodiment of the present invention, dianhydride A is more preferably 3, 4-diphenylmethanone tetracarboxylic dianhydride and pyromellitic dianhydride, diamine B is more preferably 4,4' -diaminodiphenyl ether, 4' -diamino-2, 2' -bistrifluoromethyl biphenyl and p-phenylenediamine, and additive C is more preferably sodium ascorbate.

In the polyimide precursor, the organic solvent D is one or a mixed solvent of more than one of polar solvents capable of dissolving polyamide acid at room temperature or under heating, and the organic solvent D is selected from aprotic solvents N, N-dimethylformamide, N-dimethylacetamide, N-diethylformamide, N-methyl-2-pyrrolidone, 1, 3-dimethyl-2-imidazolidinone, N-methylcaprolactam, hexamethylphosphoric triamide and dimethyl sulfoxide; ether solvents such as tetrahydrofuran, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol methylethyl ether, and diethylene glycol dimethyl ether; ketone solvents such as acetone, methyl ethyl ketone, diisobutyl ketone, diacetone alcohol, and cyclohexanone; and a mixed solvent of one or more of organic solvents such as ethyl acetate, propylene glycol monomethyl ether acetate and ethyl lactate.

Among them, N-methyl-2-pyrrolidone is preferable among the above organic solvents D.

The embodiment of the invention also provides a preparation method of the polyimide film and the polyimide film prepared by the preparation method.

s2: adding an additive C into the solution with diamine B dissolved in the step S1, wherein the dosage of the additive C accounts for 0.001-0.1%, preferably 0.01-0.1%, and more preferably 0.05% of the total diamine B;

s3: adding dianhydride A into the dissolved diamine B and additive C components for 1-5h, preferably 1h, and reacting at 40-80 ℃ for 6-10h after each dianhydride A addition until all dianhydride A is completely added, wherein the temperature is preferably 40 ℃, the reaction time is preferably 6h and 10h, and obtaining polyamic acid solution after polymerization, wherein the molar ratio of dianhydride to diamine of the polyamic acid solution is 0.95-1.10, and the molar ratio of dianhydride to diamine is preferably 1;

s4: and (3) coating and curing the polyamic acid solution obtained in the step (S3) to obtain the polyimide film.

The specific implementation method of the step S4 comprises the steps of coating the polyamide acid on a substrate, heating to remove a solvent, and performing dehydration cyclization to obtain the polyimide film, wherein the curing temperature is in the range of 60-600 ℃, the generally preferred curing temperature is 80-500 ℃, the curing procedure is generally divided into at least two stages, the first stage is heating to 150-280 ℃, then preserving heat for 10-60min, the second stage is heating to 400-500 ℃, the preserving temperature is 10-60min, the heating rate of the first stage is 0.5-5 ℃/min, and the heating rate of the second stage is 3-10 ℃/min. The film baking process may be performed under an air atmosphere, preferably a nitrogen atmosphere.

In the above production method, the solid content and viscosity of the polyamic acid solution can be controlled by the ratio of the powder material to the organic solvent D, and the lower limit of the solid content is preferably 8% from the viewpoint of reasonable productivity and economical use, and the upper limit of the solid content is preferably 20% from the viewpoint of good fluidity of the polyamic acid solution slurry, and particularly preferably 13%; the viscosity is preferably 3 to 6.9pa·s, more preferably 5.2 to 5.3pa·s, particularly preferably 5.3 from the viewpoint of coatability;

the addition of the additive C suppresses oxidation of the diamine monomer, and the entire polycondensation process is more uniform, and the uniformity of the film thickness of 10 μm to be coated is preferably within 2%, and particularly preferably 1.6%.

In the above production method, the transmittance of the polyamic acid solution is 62 to 71%, preferably 65 to 67%, particularly preferably 66%, and the transmittance of the polyamic acid solution is measured as a 10 wt% solution in N-methyl-2-pyrrolidone at a wavelength of 400nm and an optical path of 1 cm.

The polyimide film produced by the above-mentioned production method in the examples of the present invention has a low linear thermal expansion coefficient, and the linear thermal expansion coefficient at 50 to 300℃is 2 to 9ppm/K, preferably 2 to 3ppm/K, particularly preferably 2ppm/K, as measured on a film having a film thickness of 10. Mu.m.

The polyimide film produced by the above production method in the examples of the present invention has high transparency, and when a film having a film thickness of 10 μm is produced, the yellowness index is 18 to 26, preferably 21 to 22, particularly preferably 21; the transmittance at 400nm is 80 to 88%, preferably 84 to 86%, particularly preferably 86%.

The embodiment of the invention describes the polyamide acid solution slurry and the characterization method of the polyimide film in detail.

{ solid content }

Uniformly coating a polyamide acid solution slurry sample in a glass container, and weighing the mass m of the sample ₁ . The coated sample was heated in an oven, incubated at 100deg.C for 30min, then warmed to 350deg.C at 5deg.C/min, and incubated at 350deg.C for 30min. Weigh the sample after it cools ₂ . The solids content of the sample was calculated according to the following formula:

solid content= (m ₂ /m ₁ )×100％。

{ solution viscosity }

A sample of the polyamic acid solution slurry was measured using TA DHR-1 at 25℃at a speed of 0.314rad/s.

{ film thickness uniformity }

D _max : the maximum thickness of the dry film after the coating and curing of the polyamic acid precursor;

D _min : the polyamic acid precursor is coated and cured to form a dry film with a minimum thickness.

{ slurry clarity }

The polyamic acid solution slurry was measured at a wavelength of 400nm and an optical path of 1cm using a Perkinelmer model lambda 35 ultraviolet spectrophotometer.

{ molecular weight distribution }

The polyamic acid solution slurry was subjected to gel permeation chromatography using DMF+0.02mol/L H by using a Waters company in the United states ₃ PO ₄ For mobile phase testing, the sample concentration was 2mg/mL and the sample volume was 100. Mu.L.

{ yellow index and transmittance }

The cured polyimide film is tested by a Perkinelmer company model lambda 35 ultraviolet spectrophotometer according to HG/T3862-2006 standard and the transmittance according to GB/T2410-2008 standard.

{ coefficient of linear thermal expansion and glass transition temperature }

The linear expansion coefficient CTE of the cured polyimide film is measured by adopting a TA company model Q400EM thermo-mechanical analyzer, the test atmosphere is nitrogen, the heating rate is 10 ℃/min, the linear thermal expansion coefficients of different temperature intervals are tested, and the inflection point of an expansion curve is taken as the glass transition temperature of the film material.

The abbreviations for the compounds used in the examples and comparative examples are as follows.

BPDA:3,3', 4' -biphenyltetracarboxylic dianhydride

PMDA: pyromellitic dianhydride

BTDA:3, 4-diphenyl ketone tetracarboxylic dianhydride

ODPA:4, 4-Oxyphthalic dianhydride

6FDA: hexafluoro dianhydride

ODA:4,4' -diaminodiphenyl ether

PDA: para-phenylenediamine

BAPP:2, 2-bis [4- (4-aminophenoxy) phenyl ] propane

TFMB:4,4 '-diamino-2, 2' -bistrifluoromethyl biphenyl

NMP: n-methyl-2-pyrrolidone

Antioxidant 1010: tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester

Antioxidant 1098: n, N' -bis- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine

Antioxidant 168: tris (2, 4-di-tert-butylphenyl) phosphite

The starting materials of the above compounds are commercially available without particular limitation.

Example 1

A1L three-neck flask was equipped with mechanical stirring, a spherical condenser and a nitrogen guide, 400g of NMP was put into the three-neck flask, the temperature was raised to 40 ℃, 17.3026g of PDA, 6.8080g of ODA, 1.9214g of TFMB were added into the flask, and 50g of solvent was used for flushing, after complete dissolution, 0.0396g of sodium ascorbate and 18g of solvent were added, after 1 hour of reaction, 29.4215g of BPDA was added, and flushing with 25g of NMP solvent, and after 6 hours of reaction at 40 ℃, 21.8120g of PMDA was added, and after 10 hours of reaction at 40 ℃, 25g of NMP solvent was used for flushing, the polymerization reaction was completed.

The results of the performance test of the obtained polyimide precursor solution Q1 are shown in Table 1.

The curing is carried out under nitrogen atmosphere, the curing procedure is generally divided into at least two stages, wherein the first stage is to heat up to 220 ℃, then keep the temperature for 40min, the second stage is to heat up to 450 ℃, the temperature is kept for 60min, the heating rate of the first stage is 3 ℃/min, and the heating rate of the second stage is 8 ℃/min.

The test results of the cured polyimide film M1 are shown in table 2.

Example 2

A1L three-neck flask is provided with mechanical stirring, a spherical condenser and a nitrogen guide head, 400g of NMP is added into a reaction flask, the temperature is raised to 40 ℃, 17.3026g of PDA, 6.8080g of ODA and 1.9214g of TFMB are added into the flask, 50g of solvent is used for flushing, 0.0220g of hydroquinone and 18g of solvent are added after complete dissolution, 29.4215g of BPDA is added after 1h of reaction, 25g of NMP solvent is used for flushing, the temperature is controlled to 40 ℃ for 6h, 21.8120g of PMDA is added, 25g of NMP solvent is used for flushing, and the polymerization reaction is finished after 10h of reaction at the temperature is controlled to 40 ℃.

The results of the performance test of the obtained polyimide precursor solution Q2 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M2 are shown in table 2.

Example 3

A1L three-neck flask is provided with mechanical stirring, a spherical condenser and a nitrogen guide head, 400g of NMP is added into a reaction flask, the temperature is raised to 40 ℃, 17.3026g of PDA, 6.8080g of ODA and 1.9214g of TFMB are added into the flask, 50g of solvent is used for flushing, 0.2355g of antioxidant 1010 and 18g of solvent are added after complete dissolution, 29.4215g of BPDA is added after 1h of reaction, 25g of NMP solvent is used for flushing, the temperature is controlled to 40 ℃ for 6h of reaction, 21.8120g of PMDA is added, 25g of NMP solvent is used for flushing, and the polymerization reaction is finished after 10h of reaction at the temperature of 40 ℃.

The results of the performance test of the obtained polyimide precursor solution Q3 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M3 are shown in table 2.

Example 4

A1L three-neck flask is provided with mechanical stirring, a spherical condenser and a nitrogen guide head, 400g of NMP is added into a reaction flask, the temperature is raised to 40 ℃, 17.3026g of PDA, 6.8080g of ODA and 1.9214g of TFMB are added into the flask, 50g of solvent is used for flushing, 0.1274g of antioxidant 1098 and 18g of solvent are added after complete dissolution, 29.4215g of BPDA is added after reaction for 1h, 25g of NMP solvent is used for flushing, the temperature is controlled to 40 ℃ for 6h, 21.8120g of PMDA is added, 25g of NMP solvent is used for flushing, and the polymerization reaction is finished after reaction for 10h at the temperature of 40 ℃.

The results of the performance test of the obtained polyimide precursor solution Q4 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M4 are shown in table 2.

Example 5

A1L three-neck flask is provided with mechanical stirring, a spherical condenser and a nitrogen guide head, 400g of NMP is added into a reaction flask, the temperature is raised to 40 ℃, 17.3026g of PDA, 6.8080g of ODA and 1.9214g of TFMB are added into the flask, 50g of solvent is used for flushing, 0.1294g of antioxidant 168 and 18g of solvent are added after complete dissolution, 29.4215g of BPDA is added after 1h of reaction, 25g of NMP solvent is used for flushing, the temperature is controlled to 40 ℃ for 6h of reaction, 21.8120g of PMDA is added, 25g of NMP solvent is used for flushing, and the polymerization reaction is finished after 10h of reaction at the temperature is controlled to 40 ℃.

The results of the performance test of the obtained polyimide precursor solution Q5 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M5 are shown in table 2.

Example 6

A1L three-neck flask is provided with mechanical stirring, a spherical condenser and a nitrogen guide, 600g of NMP is added into a reaction flask, the temperature is raised to 40 ℃, 41.0516g of BAPP and 20.0242g of ODA are added into the flask, the flask is washed by 100g of solvent, after complete dissolution, 0.0396g of sodium ascorbate and 20g of solvent are added for reaction for 1h, 38.6676g of BTDA are added, 50g of NMP solvent is washed, the temperature is controlled to 40 ℃ for reaction for 6h, 22.9556g of ODPA is added, 50g of NMP solvent is washed, the temperature is controlled to 40 ℃ for reaction for 8h, 2.6654g of 6FDA is added, 20g of solvent is washed, the temperature is controlled to 40 ℃ for reaction for 10h, and the polymerization reaction is finished.

The results of the performance test of the obtained polyimide precursor solution Q6 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M6 are shown in table 2.

Example 7

A1L three-neck flask was equipped with mechanical stirring, a spherical condenser and a nitrogen guide, 600g of NMP was put into the reaction flask, the temperature was raised to 40 ℃, 38.5877g of BAPP, 20.0236g of ODA and 1.9214g of TFMB were added into the flask, and the flask was rinsed with 100g of solvent, after complete dissolution, 0.0396g of sodium ascorbate and 20g of solvent were added, after 1 hour of reaction, 32.2225g of BTDA were added, the flask was rinsed with 50g of NMP solvent, the reaction was carried out for 6 hours at 40℃and 31.0215g of ODPA were added, the flask was rinsed with 50g of NMP solvent, and after 10 hours of reaction at 40℃the polymerization was completed.

The results of the performance test of the obtained polyimide precursor solution Q7 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M7 are shown in table 2.

Example 8

A1L three-neck flask is provided with mechanical stirring, a spherical condenser and a nitrogen guide, 400g of NMP is added into a reaction flask, the temperature is raised to 40 ℃, 17.3026g of PDA, 6.0070g of ODA and 3.2023g of TFMB are added into the flask, 50g of solvent is used for flushing, 0.0396g of sodium ascorbate and 18g of solvent are added after complete dissolution, 29.4215g of BPDA is added after 1h of reaction, 25g of NMP solvent is used for flushing, the temperature is controlled to 40 ℃ for 6h, 21.8120g of PMDA is added, 25g of NMP solvent is used for flushing, and the polymerization reaction is finished after 10h of reaction at the temperature is controlled to 40 ℃.

The results of the performance test of the obtained polyimide precursor solution Q8 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M8 are shown in table 2.

Example 9

A1L three-neck flask is provided with mechanical stirring, a spherical condenser and a nitrogen guide, 200g of NMP is added into a reaction flask, the temperature is raised to 40 ℃, 17.3026g of PDA, 6.8080g of ODA and 1.9214g of TFMB are added into the flask, 50g of solvent is used for flushing, 0.0396g of sodium ascorbate and 10g of solvent are added after complete dissolution, 26.4794g of BPDA is added after 1h of reaction, 20g of NMP solvent is used for flushing, the temperature is controlled to 40 ℃ for 6h of reaction, 21.8120g of PMDA is added, 20g of NMP solvent is used for flushing, and the polymerization reaction is finished after 10h of reaction at the temperature of 40 ℃.

The results of the performance test of the obtained polyimide precursor solution Q9 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M9 are shown in table 2.

Example 10

A1L three-neck flask is provided with mechanical stirring, a spherical condenser and a nitrogen guide, 600g of NMP is added into a reaction flask, the temperature is raised to 40 ℃, 19.4654g of PDA, 6.8080g of ODA and 1.9214g of TFMB are added into the flask, 50g of solvent is used for flushing, 0.0396g of sodium ascorbate and 15g of solvent are added after complete dissolution, 29.4215g of BPDA is added after 1h of reaction, 25g of NMP solvent is used for flushing, the temperature is controlled to 40 ℃ for 6h of reaction, 21.8120g of PMDA is added, 25g of NMP solvent is used for flushing, and the polymerization reaction is finished after 10h of reaction at the temperature of 40 ℃.

The results of the performance test of the obtained polyimide precursor solution Q10 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M10 are shown in table 2.

Example 11

A1L three-neck flask is provided with mechanical stirring, a spherical condenser and a nitrogen guide, 400g of NMP is added into a reaction flask, the temperature is raised to 40 ℃, 17.3026g of PDA, 6.8080g of ODA and 1.9214g of TFMB are added into the flask, 50g of solvent is used for flushing, after complete dissolution, 0.0004g of sodium ascorbate and 18g of solvent are added for reaction for 1 hour, 29.4215g of BPDA is added, 25g of NMP solvent is used for flushing, the temperature is controlled to 40 ℃ for reaction for 6 hours, 21.8120g of PMDA is added, 25g of NMP solvent is used for flushing, and the polymerization reaction is completed after 10 hours of reaction at the temperature of 40 ℃.

The results of the performance test of the obtained polyimide precursor solution Q11 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M11 are shown in table 2.

Example 12

A1L three-neck flask is provided with mechanical stirring, a spherical condenser and a nitrogen guide, 400g of NMP is added into a reaction flask, the temperature is raised to 40 ℃, 17.3026g of PDA, 6.8080g of ODA and 1.9214g of TFMB are added into the flask, 50g of solvent is used for flushing, after complete dissolution, 0.0021g of sodium ascorbate and 18g of solvent are added for reaction for 1h, 29.4215g of BPDA is added, 25g of NMP solvent is used for flushing, the temperature is controlled to 40 ℃ for reaction for 6h, 21.8120g of PMDA is added, 25g of NMP solvent is used for flushing, and the polymerization reaction is completed after 10h of reaction at the temperature of 40 ℃.

The results of the performance test of the obtained polyimide precursor solution Q12 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M12 are shown in table 2.

Example 13

A1L three-neck flask was equipped with mechanical stirring, a spherical condenser and a nitrogen guide, 400g of NMP was put into the reaction flask, the temperature was raised to 40 ℃, 17.3026g of PDA, 6.8080g of ODA, 1.9214g of TFMB were added into the flask, and after complete dissolution, 0.0040g of sodium ascorbate and 18g of solvent were added, after 1 hour of reaction, 29.4215g of BPDA was added, and the mixture was washed with 25g of NMP, reacted for 6 hours at 40℃and 21.8120g of PMDA was added, and after 10 hours of reaction at 40℃, the polymerization was completed with 25g of NMP solvent.

The results of the performance test of the obtained polyimide precursor solution Q13 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M13 are shown in table 2.

Example 14

A1L three-neck flask is provided with mechanical stirring, a spherical condenser and a nitrogen guide, 400g of NMP is added into a reaction flask, the temperature is raised to 40 ℃, 17.3026g of PDA, 6.8080g of ODA and 1.9214g of TFMB are added into the flask, 50g of solvent is used for flushing, 0.0198g of sodium ascorbate and 18g of solvent are added after complete dissolution, 29.4215g of BPDA is added after 1h of reaction, 25g of NMP solvent is used for flushing, the temperature is controlled to 40 ℃ for 6h of reaction, 21.8120g of PMDA is added, 25g of NMP solvent is used for flushing, and the polymerization reaction is finished after 10h of reaction at the temperature of 40 ℃.

The results of the performance test of the obtained polyimide precursor solution Q14 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M14 are shown in table 2.

Comparative example 1

Comparative examples 1 to 5 the same procedure was followed as in examples 1 to 5 except that no additive C was added, except that a 1L three-necked flask was equipped with mechanical stirring, a spherical condenser and a nitrogen introduction, 400g of NMP was charged into the flask, the temperature was raised to 40℃and 17.3026g of PDA, 6.8080g of ODA, 1.9214g of TFMB was added into the flask and washed with 50g of solvent, after complete dissolution 29.4215g of BPDA was added, washed with 25g of NMP solvent, reacted at 40℃for 6 hours, 21.8120g of PMDA was added, washed with 25g of NMP solvent, reacted at 40℃for 10 hours, and the polymerization was completed.

The results of the performance test of the obtained polyimide precursor solution Q15 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M15 are shown in table 2.

Comparative example 2

Comparative example 6 the procedure was the same as in example 6 except that no additive C was added, except that a 1L three-necked flask was equipped with mechanical stirring, a spherical condenser and a nitrogen introduction, 600g of NMP was charged into the flask, the temperature was raised to 40℃and 41.0516g of BAPP and 20.0242g of ODA were added into the flask and washed with 100g of solvent, after complete dissolution 38.6676g of BTDA was added, washed with 50g of NMP solvent, reacted for 6 hours at 40℃and 22.9556g of ODPA was added, washed with 50g of NMP solvent, reacted for 8 hours at 40℃and 2.6654g of 6FDA were added, washed with 20g of solvent, reacted for 10 hours at 40℃and the polymerization was completed.

The results of the performance test of the obtained polyimide precursor solution Q16 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M16 are shown in table 2.

Comparative example 3

Comparative example 1A three-necked flask equipped with mechanical stirring, a spherical condenser and a nitrogen introduction head was charged with an excess of additive C,1L of the three-necked flask, 400g of NMP was charged into the flask, the temperature was raised to 40℃and 17.3026g of PDA, 6.8080g of ODA, 1.9214g of TFMB were added into the flask and rinsed with 50g of solvent, after complete dissolution, 0.3960g of sodium ascorbate and 18g of solvent were added, after 1 hour of reaction, 29.4215g of BPDA was added, rinsed with 25g of NMP solvent, reacted for 6 hours at 40℃under control, then 21.8120g of PMDA was added, rinsed with 25g of NMP solvent, reacted for 10 hours at 40℃under control, and the polymerization was completed.

The results of the performance test of the obtained polyimide precursor solution Q17 are shown in Table 1.

The curing procedure was the same as in example 1, and the polyimide film M17 after curing, since M17 had frosted during the curing, was not formed into a film, and thus the data in table 2 was not shown.

Comparative example 4

Comparative example 6, a three-necked flask of 1L, which had 5% by mole of the total dianhydride and diamine, was equipped with mechanical stirring, a spherical condenser and a nitrogen introduction, was charged with 600g of NMP as a solvent, heated to 40℃and was charged with 41.0516g of BAPP and 20.0242g of ODA, and rinsed with 100g of solvent, after complete dissolution, 0.0396g of sodium ascorbate and 20g of solvent were added, reacted for 1 hour, 38.6676g of BTDA was added, rinsed with 50g of NMP solvent, reacted for 6 hours at 40℃under control, and then 18.6126g of ODPA was added, rinsed with 50g of NMP solvent, reacted for 8 hours at 40℃under control, and then 8.8848g of 6FDA was added, rinsed with 20g of solvent, reacted for 10 hours at 40℃under control, and the polymerization was completed.

The results of the performance test of the obtained polyimide precursor solution Q18 are shown in Table 1.

The curing procedure was the same as in example 1, and the test results of the cured polyimide film M18 are shown in table 2.

TABLE 1 polyimide precursor Performance parameters

TABLE 2 polyimide film performance parameters

As can be seen from Table 1, examples 1 to 5, to which the additive C was added, had higher slurry transparency than comparative example 1, to which the additive C was not added, kept the sodium ascorbate and fluorine atom contents unchanged, and changed diamine and dianhydride monomer components, example 7 had a larger degree of deterioration in the coefficient of thermal expansion and glass transition temperature than example 1, although the slurry transparency and film-forming after-pass ratio were close to each other, example 8 had a better slurry transparency and film-forming after-pass ratio by setting the molar amount of fluorine-containing structure to 5mol% or less of the total monomer when the sodium ascorbate ratio was the same as example 1, examples 9 and 10 had better slurry transparency and film-passing ratio improving effect, and slurries of different solid contents and different viscosities were easily obtained by adjusting the ratios of 0.95 to 1.1, examples 11 to 14 were satisfied, in the range of 0.001mol% to 0.1mol%, with the increase in the addition ratio of sodium ascorbate, the transparency and film-forming after-pass ratio were remarkably increased, and the polyimide was preferably 0.01mol% and 0.1mol% after-pass ratio was remarkably increased, and the polyimide was not added, and the polyimide was prepared as a film was not uniform in the film-forming after-pass ratio was compared with the polyimide, and the polyimide was not added, because the additive C was more likely to have a uniform and the film-forming after-pass ratio was not affected by the film, and the film was not affected by the addition, and the film was prepared, and the film was stable due to the effect was not had a good film-forming, and was stable due to the effect was compared to the addition, and was prepared.

In addition, as can be seen from table 2, the polyimide films of examples 1 to 5 and example 6 to which the additive C was added maintained excellent in terms of yellow index, 400nm transmittance, thermal expansion coefficient, glass transition temperature, film thickness uniformity, and the like, as compared with comparative examples 1 and 2 to which the additive C was not added.

In comparative example 3, 1mol% of sodium ascorbate was added during the reaction, and the polyimide film after film formation showed a frosting phenomenon, indicating that the introduction of excessive additive C resulted in a problem of system compatibility, and in comparative example 4, the fluorine-containing dianhydride monomer was added to 5mol% of the total monomer amount, and although the transparency of the slurry and film remained excellent, the glass transition temperature was low, and the film had a risk of failure at the stage of high temperature processing.

It should be noted that, based on the disclosure and the description of the foregoing specification, those skilled in the art may also make changes and modifications to the above-described embodiments. Therefore, the invention is not limited to the specific embodiments disclosed and described above, but equivalent modifications and variations of the invention should be made within the scope of the claims of the present invention. In addition, although specific terms are used in the present specification, these terms are for convenience of description only and do not limit the present invention in any way.

Claims

1. A polyimide precursor, which is characterized in that the polyimide precursor is prepared by the reaction of dianhydride A, diamine B and an additive C, wherein the diamine B contains fluorine-containing diamine, and the molar quantity of the fluorine-containing diamine is not more than 5% of the total diamine molar quantity;

the dianhydride A is a combination of 3,3', 4' -biphenyl tetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA);

the diamine B is a combination of 4,4' -diaminodiphenyl ether (ODA), p-Phenylenediamine (PDA), and 4,4' -diamino-2, 2' -bistrifluoromethyl biphenyl (TFMB);

the additive C comprises sodium ascorbate, hydroquinone, pentaerythritol tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], N' -bis- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexamethylenediamine or tris (2, 4-di-tert-butylphenyl) phosphite, wherein the dosage of the additive C accounts for 0.01-0.1% of the total diamine.

2. A polyimide precursor according to claim 1, wherein the additive C is sodium ascorbate.

3. A polyimide film obtained by imidizing the polyimide precursor according to any one of claims 1 to 2.

4. A polyimide film according to claim 3, wherein the polyimide film has a thermal expansion coefficient of 2 to 3ppm/K, a yellowness index of 21 to 22, and a transmittance at a wavelength of 400nm of 83% to 86%.

5. A method for producing the polyimide film according to any one of claims 3 to 4, comprising the steps of:

s3: adding dianhydride A into the components of the dissolved diamine B and the additive C for 1h for a plurality of times, reacting at 40 ℃ for 6-10h after each dianhydride A is added until all dianhydride A is completely added, and obtaining polyamic acid solution after polymerization, wherein the molar ratio of dianhydride to diamine of the polyamic acid solution is 0.95-1.10;