Polyamic acid solution, preparation method thereof and raw material composition for preparing polyamic acid solution

Abstract

The invention provides a polyamide acid solution, a preparation method thereof and a raw material composition for preparing the polyamide acid solution. The preparation method comprises the following step: in the reaction process of aromatic dianhydride and diamine, adding a composition of pentamethylene diamine and polyacid as an auxiliary agent. The polyamide acid solution is prepared by the preparation method. The raw material composition for preparing the polyamide acid solution comprises a solvent, an auxiliary agent, diamine and aromatic dianhydride, wherein the auxiliary agent is a composition of pentamethylene diamine and polyacid. According to the preparation method of the polyamic acid solution, the dynamic viscosity of the polyamic acid solution can be reduced by introducing the auxiliaries, the polyamic acid solution is easy to store, and the stability of the polyamic acid solution is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a polyamic acid solution and a preparation method thereof, and a raw material composition for preparing the polyamic acid solution. Background Art

[0002] At present, polyimide has become an indispensable and important "golden material" in the fields of electronics, machinery, aerospace, communications, flexible displays, etc. This material structure contains heterocyclic polymers (R-CO-NH-CO-R') with imide groups. Due to its excellent mechanical properties, high and low temperature resistance, and dimensional stability, it is often made into films, fibers, resins, foams, composite materials, etc. This material has attracted widespread attention due to its stable performance. Both the "two-step method" and the "one-step method" can prepare polyimide. Aromatic dianhydrides and diamines are polymerized in a non-protonic polar solvent to obtain a polyamic acid solution, and then thermal imidization or chemical imidization is performed to obtain polyimide. Therefore, the characteristics of the polyamic acid slurry as a precursor determine the quality of the final product.

[0003] The solid content and dynamic viscosity of polyamic acid slurry are very important indicators that affect the performance of polyimide products. In particular, most industrial production at this stage uses spraying, casting, spinning and other methods to prepare coatings, films and other products, which require high ductility of the slurry. However, polyamic acid slurry is prone to form a large number of hydrogen bonds within and between molecular chains, and the ionization of carboxylic acid groups enhances the polyelectrolyte effect, so that slurries with high solid content usually have very high dynamic viscosity, and even gelation occurs, which is not conducive to subsequent processing and application; reducing the solid content can reduce the dynamic viscosity of the slurry to a certain extent, but this method will increase the amount of solvent used, affect product quality and reduce production efficiency.

[0004] In order to solve the problem of poor fluidity of slurry under high solid content conditions, CN101558102A discloses a method for regulating the water content of the reaction system; CN106589371A proposes a method for controlling the viscosity of polyamic acid by adding tetracarboxylic acid to the reaction system of dianhydride and diamine, but this method requires operation under N2 atmosphere, which increases the complexity of the reaction; CN104292459A discloses a method for adjusting the viscosity by adding polysiloxane adhesion promoters, but this method has the problems of requiring multiple additions, replenishing solvents, and long waiting time for addition.

[0005] In addition, CN103788651A discloses a method for preparing a polyamic acid solution with low apparent viscosity. The method adds 5% to 40% trimethylchlorosilane of the mass of the polyamic acid to the polyamic acid solution, stirs it at room temperature for 1 to 5 hours, and obtains a polyamic acid solution with an apparent viscosity of 0.2 to 1.5 thousand centipoise. However, the content of the auxiliary agent trimethylchlorosilane used in this method accounts for a large proportion, which increases the difficulty of subsequent material processing and removal of the auxiliary agent.

[0006] CN106589368A discloses a polyamic acid composition, a preparation method and an application thereof. The preparation method of the polyamic acid composition adds tetracarboxylic acid by controlling the ratio of the addition amount, and adds tetracarboxylic dianhydride in batches to control the viscosity of the polyamic acid solution. However, the method needs to be operated under N2 atmosphere, which increases the difficulty of experimental operation, and the stability of the polyamic acid during storage is not optimized.

[0007] CN115678010A discloses a polyamic acid, a polyimide resin and a preparation method thereof. The preparation method of the polyamic acid adds a diamine containing a nitrogen-containing heteroaromatic ring to a solvent, adds a dianhydride containing a flexible chain structure three times, and prepares a polyamic acid, and finally prepares a low-temperature imidized polyimide material with good thermal stability and mechanical properties using this polyamic acid. However, the preparation method needs to be fed in batches, increases the operating steps, and does not explore the viscosity and storage stability of the polyamic acid solution.

[0008] The depolymerization of polyamic acid slurry during storage is the main factor causing its viscosity to decrease. The essential reason for this degradation process is that the carboxylic acid hydroxyl group in the polyamic acid and the amide carbonyl group in the molecule undergo a depolymerization reaction through nucleophilic addition, and the moisture present in the system causes the anhydride end group formed by the depolymerization of the molecular chain to hydrolyze to form two carboxylic acid groups. This irreversible reaction causes the properties of the polyamic acid to change, resulting in a short shelf life of the slurry and poor batch stability. There are currently a variety of means to slow down the spontaneous degradation of polyamic acid, such as dry preparation, ultra-low temperature storage, drying with molecular sieves, molecular chain end-capping, etc. However, these methods have problems such as cumbersome processes, high reagent toxicity, and high process costs.

[0009] Therefore, it is a difficult problem to be solved in the art to synthesize a polyamic acid slurry having low dynamic viscosity, easy storage, and high stability by simple preparation means. Summary of the invention

[0010] In order to solve the above technical problems, the purpose of the present invention is to provide a polyamic acid solution and a preparation method thereof and a raw material composition for preparing the polyamic acid solution. The preparation method of the polyamic acid solution of the present invention can reduce the dynamic viscosity of the polyamic acid solution by introducing an auxiliary agent, and make the polyamic acid solution easy to store and improve its stability.

[0011] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a polyamic acid solution, which comprises the following steps: during the reaction of aromatic dianhydride and diamine, adding a composition of pentamethylenediamine and polyacid as an auxiliary agent.

[0012] According to a specific embodiment of the present invention, preferably, the method for preparing the polyamic acid solution comprises the following steps:

[0013] (I) mixing a solvent, a diamine and an aromatic dianhydride;

[0014] (II) reacting the mixed solution obtained in step (I) to obtain the polyamic acid solution;

[0015] An auxiliary agent is added in step (I) or (II), wherein the auxiliary agent is a combination of pentamethylenediamine and polyacid.

[0016] In the above preparation method, preferably, in the auxiliary agent, the polyacid includes pyrophosphoric acid and / or triphosphoric acid.

[0017] In the above preparation method, preferably, in the auxiliary agent, the mass ratio of the polyacid to pentamethylenediamine is (0.01-0.5):1.

[0018] In the above preparation method, preferably, based on 100% by mass of the solvent, the amount of pentamethylenediamine added in the auxiliary agent is 0.1-2% by mass.

[0019] In the above preparation method, preferably, the solvent includes an aprotic polar solvent. More preferably, the solvent includes one or a combination of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide and hexamethylphosphoric triamide.

[0020] In the above preparation method, preferably, the diamine includes one or a combination of aromatic diamines and aliphatic diamines. More preferably, the diamine includes one or a combination of p-phenylenediamine, 4,4'-diaminodiphenyl ether, hydroquinone diether diamine, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylmethane, ethylenediamine, 1,6-hexanediamine and bisphenol A diether diamine.

[0021] In the above preparation method, preferably, the aromatic dianhydride includes one or a combination of the following: pyromellitic dianhydride, biphenyl tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ketone tetracarboxylic dianhydride, triphenyl diether dianhydride, diphenyl ether dianhydride, diphenyl sulfide dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, hydroquinone diether dianhydride, hexafluoro dianhydride, resorcinol diether dianhydride and bisphenol A diether dianhydride.

[0022] In the above preparation method, preferably, the molar ratio of the diamine to the aromatic dianhydride is 1:(0.995-1.01).

[0023] In the above preparation method, preferably, the total mass of the diamine and the aromatic dianhydride accounts for 10-30% of the total mass of the reaction system. Wherein, the reaction system is a combination of the solvent, auxiliary agent, diamine and aromatic dianhydride of the present invention.

[0024] In the above preparation method, preferably, the system temperature of steps (I) and (II) is -15 to 50°C.

[0025] In the above preparation method, preferably, the reaction time of step (II) is 1-10 hours.

[0026] The second aspect of the present invention provides a polyamic acid solution, which is prepared by the above-mentioned method for preparing the polyamic acid solution.

[0027] According to a specific embodiment of the present invention, preferably, the dynamic viscosity of the polyamic acid solution is 8000 cp or less, more preferably 6000 cp or less.

[0028] According to a specific embodiment of the present invention, preferably, the solid content of the polyamic acid solution is greater than 10 wt %.

[0029] According to a specific embodiment of the present invention, preferably, the intrinsic viscosity of the polyamic acid solution is 2.5 dL / g or less, and more preferably 1.8 dL / g or less.

[0030] The third aspect of the present invention provides a raw material composition for preparing a polyamic acid solution, which includes a solvent, an auxiliary agent, and a diamine and an aromatic dianhydride, wherein the auxiliary agent is a composition of pentamethylenediamine and a polyacid; the raw material composition is used to prepare a polyamic acid solution using the above-mentioned preparation method.

[0031] The present invention provides a polyamic acid solution and a preparation method thereof, and a raw material composition for preparing the polyamic acid solution. The preparation method of the polyamic acid solution of the present invention can reduce the dynamic viscosity of the polyamic acid solution by introducing an auxiliary agent, and make the polyamic acid solution easy to store and improve its stability. The preparation method of the polyamic acid solution of the present invention can synthesize a polyamic acid solution with high stability and controllable viscosity.

[0032] The technical solution of the present invention has at least the following beneficial effects:

[0033] 1. The present invention reduces the dynamic viscosity of the polyamic acid solution. The present invention uses a composition of pentamethylenediamine and polyacid as an auxiliary agent, wherein the free hydrogen ions in the polyacid can weaken the hydrogen bonding between polyamic acid molecules and within the molecules, and shield the polyelectrolyte effect of the polyamic acid, thus having a significant effect on reducing the dynamic viscosity of the system.

[0034] 2. The present invention improves the stability of the polyamic acid solution. The present invention uses a composition of pentamethylenediamine and polyacid as an auxiliary agent. The auxiliary agent contains a reactant group that can make the system proceed in the forward direction, prolong the storage time, improve the stability, and solve the problem that the polyamic acid solution is easy to degrade and has a short storage period.

[0035] 3. The present invention uses a composition of pentamethylenediamine and polyacid as an auxiliary agent, which can be dissolved and does not affect the performance of subsequent materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a curve chart showing the change in intrinsic viscosity of the polyamic acid solution prepared in Example 2 when stored at 10°C. DETAILED DESCRIPTION

[0037] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0038] The invention provides a method for preparing a polyamic acid solution, which comprises the following steps: in the reaction process of aromatic dianhydride and diamine, adding a composition of pentamethylenediamine and polyacid as an auxiliary agent.

[0039] Specifically, the preparation method of the present invention may include the following steps:

[0040] (I) adding a solvent, a diamine and an aromatic dianhydride into a reaction vessel;

[0041] (II) reacting the mixed solution obtained in step (I) to obtain the polyamic acid solution;

[0042] An auxiliary agent is added in step (I) or (II), wherein the auxiliary agent is a combination of pentamethylenediamine and polyacid.

[0043] Among the auxiliary agents, the polyacid preferably includes pyrophosphoric acid and / or triphosphoric acid.

[0044] The preparation method of the invention can prepare a polyamic acid solution with controllable viscosity and high stability by utilizing specific auxiliary agents.

[0045] The free hydrogen ions in the polyacid in the additive can weaken the hydrogen bonding between polyamic acid molecules and within the molecules, and shield the polyelectrolyte effect of polyamic acid, so it has a significant effect on reducing the dynamic viscosity of the system. In addition, the groups containing reactants in the additive can make the system always proceed in the forward direction, prolong the storage time, improve the stability, and solve the problem of easy degradation and short storage period of polyamic acid solution. At the same time, because the additive can be dissolved, it does not affect the performance of subsequent materials.

[0046] In the present invention, a non-protonic polar solvent is preferably used as the solvent. As the non-protonic polar solvent, one or a combination of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide and hexamethylphosphoric triamide is preferably used.

[0047] In the present invention, as the diamine, aromatic or aliphatic diamines are preferably used, among which one or a combination of p-phenylenediamine, 4,4'-diaminodiphenyl ether, hydroquinone diether diamine, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylmethane, ethylenediamine, 1,6-hexanediamine and bisphenol A diether diamine is preferred.

[0048] In the present invention, as the aromatic dianhydride, it is preferred to use one or a combination of the following: pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ketone tetracarboxylic dianhydride, triphenyl diether dianhydride, diphenyl ether dianhydride, diphenyl sulfide dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, hydroquinone diether dianhydride, hexafluoro dianhydride, resorcinol diether dianhydride and bisphenol A diether dianhydride.

[0049] Regarding the usage ratio of the diamine and the aromatic dianhydride, in terms of molar ratio, the molar ratio of the diamine to the aromatic dianhydride may be 1:(0.995-1.01).

[0050] Furthermore, the total amount of the diamine and the aromatic dianhydride used may be 10-30% by mass relative to 100% by mass of the reaction system, wherein the reaction system is a combination of the solvent, the auxiliary agent, the diamine and the aromatic dianhydride of the present invention.

[0051] In the present invention, an auxiliary agent is added to the reaction system for polymerizing diamine and aromatic dianhydride. The auxiliary agent is a composition of pentamethylenediamine and polyacid.

[0052] Regarding the amount of the auxiliary agent added, the amount of pentamethylenediamine added is 0.1-2% by mass relative to 100% by mass of the aprotic polar solvent used in the reaction system. The amount of the polyacid added is preferably less than that of pentamethylenediamine. The mass ratio of the polyacid to pentamethylenediamine is preferably (0.01-0.5):1.

[0053] In some specific embodiments of the present invention, a non-protonic polar solvent and one of the diamine and the aromatic dianhydride can be first added to the reaction container to dissolve, and then the other of the diamine and the aromatic dianhydride is added to react to obtain the polyamic acid solution; and the auxiliary agent is added at any time before the reaction or after the reaction. There is no special limitation on the order of adding the diamine and the aromatic dianhydride. Those skilled in the art are familiar with the positive addition method of adding the diamine first and then the aromatic dianhydride, the reverse addition method of adding the aromatic dianhydride first and then the diamine, and the simultaneous addition method; preferably, the positive addition method is adopted, that is, the diamine is added first and then the aromatic dianhydride. When adding the components of the diamine and the aromatic dianhydride that have not been added first, they can be added all at once or in batches. When adding in batches, they can be added in three or more times. Preferably, a non-protonic polar solvent and diamine are first added to a reaction container to dissolve, and then aromatic dianhydride is added all at once or in batches (more preferably at least in three batches) to react to obtain the polyamic acid solution; and auxiliary agents are added at any time before the reaction or after the reaction.

[0054] There is no particular limitation on the system temperature, as long as it is a temperature at which the diamine and the aromatic dianhydride can be dissolved and the polymerization reaction can proceed. The temperature in step (I) and step (II) may be the same or different. The system temperature in step (I) and step (II) is preferably -15 to 50°C, more preferably -5 to 30°C.

[0055] The reaction time in step (II) is not particularly limited, but is preferably 1 to 10 hours, more preferably 2 to 5 hours.

[0056] According to the method for preparing a polyamic acid solution of the present invention, a polyamic acid solution having high solid content and low dynamic viscosity, which is convenient for subsequent material processing, easy to store and highly stable can be prepared.

[0057] The dynamic viscosity of the prepared polyamic acid solution is 8000 centipoise or less, preferably 6000 centipoise or less.

[0058] The solid content of the prepared polyamic acid solution is 10 wt % or more, preferably 15 wt % or more, and there is no particular upper limit, for example, 40 wt % or less.

[0059] The intrinsic viscosity of the prepared polyamic acid solution is 2.5 dL / g or less, preferably 1.8 dL / g or less.

[0060] The technical scheme of the present invention is specifically described below through examples and comparative examples, but the present invention is not limited to these examples and can of course be implemented in various modifications within the scope of the gist of the present invention.

[0061] The measuring methods used in the Examples and Comparative Examples are as follows.

[0062] (1) Solid content

[0063] The solid content was calculated by the following formula.

[0064] Solid content (%) = solid mass (g) / total mass (g) × 100

[0065] (2) Intrinsic viscosity

[0066] Use dimethylformamide to dilute to 0.5% solution, use Hangzhou Zhuoxiang Technology Co., Ltd. IV6600 Ubbelohde viscometer for measurement, select viscosity tube with inner diameter of 0.58mm. Pour the solution through filter paper to the scale line of viscosity tube at 25℃, click start, and the viscosity can be automatically obtained.

[0067] (3) Dynamic viscosity

[0068] The measurement was performed using an Anton Paar Visco QC 300 kinematic viscometer. The measurement conditions were as follows: running time 30 s, rotation speed 20 rpm, rotor No. 4, and temperature was room temperature.

[0069] (4) Storage stability

[0070] The polyamic acid solution obtained in Example 2 was stored at 10° C., and its intrinsic viscosity was measured at 0, 24, 48, 96, 168, 336, 504, 840 and 1680 hours after storage, and a curve was drawn.

[0071] Example 1

[0072] This embodiment provides a polyamic acid solution, which is prepared by the following steps:

[0073] 20 g of N-methylpyrrolidone and 0.5535 g (9.21 mmol) of ethylenediamine were added into a three-necked flask, stirred to dissolve, then 2.015 g (9.24 mmol) of pyromellitic anhydride was added, and the reaction was stirred at 0°C for 5 hours, then 0.4662 g of auxiliary agent (0.1554 g of triphosphoric acid and 0.3108 g of pentamethylenediamine) was added, and stirred evenly to obtain a polyamic acid solution with a solid content of 11 wt%, an intrinsic viscosity of 1.97 dL / g, and a dynamic viscosity of 4120 centipoise.

[0074] Example 2

[0075] This embodiment provides a polyamic acid solution, which is prepared by the following steps:

[0076] 70g of N,N-dimethylformamide and 0.1176g of auxiliary agents (0.0196g of pyrophosphoric acid and 0.098g of pentamethylenediamine) were added into a three-necked flask, stirred and dissolved at -10°C, 2.7354g (25.29mmol) of p-phenylenediamine was added, stirred and dissolved, 5.5381g (25.39mmol) of pyromellitic dianhydride was added, and the reaction was stirred at 10°C for 3 hours to obtain a polyamic acid solution with a solid content of 11wt%, an intrinsic viscosity of 2.25dL / g, and a dynamic viscosity of 6610 centipoise.

[0077] Figure 1 This is a curve diagram of the change in intrinsic viscosity of the polyamic acid solution prepared in this example when stored at 10°C. Figure 1 It can be seen that the intrinsic viscosity of the polyamic acid solution decreases slowly when stored at 10° C. for more than 1500 hours, and thus the polyamic acid solution has excellent storage stability.

[0078] Example 3

[0079] This embodiment provides a polyamic acid solution, which is prepared by the following steps:

[0080] 80.74 g of N,N-dimethylacetamide and 0.6297 g of auxiliary agents (0.1453 g of pyrophosphoric acid and 0.4844 g of pentamethylenediamine) were added to a three-necked flask, and then 3.8131 g (35.26 mmol) of p-phenylenediamine was added. After stirring and dissolving, 10.3742 g (35.26 mmol) of biphenyltetracarboxylic dianhydride was added. The reaction was stirred at 5°C for 2 hours to obtain a polyamic acid solution with a solid content of 15 wt%, an intrinsic viscosity of 1.65 dL / g, and a dynamic viscosity of 5500 centipoise.

[0081] Example 4

[0082] This embodiment provides a polyamic acid solution, which is prepared by the following steps:

[0083] 62.47g of dimethyl sulfoxide and 8.2858g (26.71mmol) of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride were added to a three-necked flask, stirred and dissolved, and then 1.2338g of auxiliary agents (0.2468g of triphosphoric acid and 0.987g of pentamethylenediamine) and 5.7839g (26.74mmol) of 4,4'-diaminodiphenyl sulfide were added. The reaction was stirred at -15°C for 4 hours to obtain a polyamic acid solution with a solid content of 18wt%, an intrinsic viscosity of 1.71dL / g, and a dynamic viscosity of 6990 centipoise.

[0084] Example 5

[0085] This embodiment provides a polyamic acid solution, which is prepared by the following steps:

[0086] 70.28g of hexamethylphosphoric acid triamide and 0.1482g of auxiliary agents (0.0287g of triphosphoric acid and 0.1195g of pentamethylenediamine) were added to a three-necked flask, and then 7.1355g (35.99mmol) of 4,4'-diaminodiphenylmethane was added. After stirring and dissolving, 10.6007g (36.03mmol) of biphenyltetracarboxylic dianhydride was added. The reaction was stirred at 25°C for 10 hours to obtain a polyamic acid solution with a solid content of 20wt%, an intrinsic viscosity of 1.88dL / g, and a dynamic viscosity of 5750 centipoise.

[0087] Example 6

[0088] This embodiment provides a polyamic acid solution, which is prepared by the following steps:

[0089] 58.13 g of dimethyl sulfoxide, 8.2822 g (38.29 mmol) of 4,4'-diaminodiphenyl sulfide and 1.023 g of additives (0.093 g of pyrophosphoric acid and 0.93 g of pentamethylenediamine) were added to a three-necked flask, stirred and dissolved, and then 16.9652 g (38.21 mmol) of hexafluorodianhydride was added. The mixture was stirred and reacted at 35°C for 7 hours to obtain a polyamic acid solution with a solid content of 30 wt%, an intrinsic viscosity of 1.63 dL / g, and a dynamic viscosity of 7970 centipoise.

[0090] Example 7

[0091] This embodiment provides a polyamic acid solution, which is prepared by the following steps:

[0092] 57.26g of N,N-dimethylformamide and 1.1567g of auxiliary agents (0.0115g of triphosphoric acid and 1.1452g of pentamethylenediamine) were added to a three-necked flask, and then 5.6083g (48.26mmol) of 1,6-hexanediamine was added. After stirring and dissolving, 10.5679g (48.45mmol) of pyromellitic dianhydride was added. The reaction was stirred at 20°C for 8 hours to obtain a polyamic acid solution with a solid content of 22wt%, an intrinsic viscosity of 1.96dL / g, and a dynamic viscosity of 6500 centipoise.

[0093] Example 8

[0094] This embodiment provides a polyamic acid solution, which is prepared by the following steps:

[0095] 80.64g N-methylpyrrolidone, 1.1539g auxiliary agent (0.0653g pyrophosphate, 1.0886g pentamethylenediamine) and 9.593g (44.35mmol) 4,4'-diaminodiphenyl sulfide were added into a three-necked flask, stirred and dissolved, and then 23.0888 (44.36mmol) bisphenol A diether dianhydride was added, and stirred at 30°C for 7 hours to obtain a polyamic acid solution with a solid content of 29wt%, an intrinsic viscosity of 1.74dL / g, and a dynamic viscosity of 7810 centipoise.

[0096] Example 9

[0097] This embodiment provides a polyamic acid solution, which is prepared by the following steps:

[0098] 90.34g of hexamethylphosphoric triamide and 2.187g of auxiliary agents (0.5789g of pyrophosphoric acid and 1.6081g of pentamethylenediamine) were added into a three-necked flask, and then 8.6891g (80.35mmol) of p-phenylenediamine was added. After stirring and dissolving, 23.2287g (79.95mmol) of biphenyltetracarboxylic dianhydride was added. The mixture was stirred and reacted at 20°C for 4 hours to obtain a polyamic acid solution with a solid content of 26wt%, an intrinsic viscosity of 1.52dL / g, and a dynamic viscosity of 6710 centipoise.

[0099] Example 10

[0100] This embodiment provides a polyamic acid solution, which is prepared by the following steps:

[0101] 76.35 g of N-methylpyrrolidone, 10.6415 g (41.21 mmol) of diphenyl sulfide dianhydride, 0.5826 g of auxiliary agents (0.055 g of triphosphoric acid, 0.5726 g of pentamethylenediamine) and 2.4791 g (41.25 mmol) of ethylenediamine were added into a three-necked flask, stirred and reacted at 40° C. for 9 hours to obtain a polyamic acid solution with a solid content of 15 wt%, an intrinsic viscosity of 1.71 dL / g and a dynamic viscosity of 3840 centipoise.

[0102] Comparative Example 1

[0103] This comparative example provides a polyamic acid solution, and its preparation steps are basically the same as those of Example 5, except that: no auxiliary agent is added in this comparative example, and the obtained polyamic acid solution has a solid content of 20wt%, an intrinsic viscosity of 2.57dL / g, and a dynamic viscosity of 30478 centipoise.

[0104] Comparative Example 2

[0105] This comparative example provides a polyamic acid solution, and its preparation steps are basically the same as those of Example 8, except that: no auxiliary agent is added in this comparative example, and the obtained polyamic acid solution has a solid content of 29wt%, an intrinsic viscosity of 2.68dL / g, and a dynamic viscosity of 38655 centipoise.

[0106] Comparative Example 3

[0107] This comparative example provides a polyamic acid solution, and its preparation steps are basically the same as those of Example 9, except that: no auxiliary agent is added in this comparative example, and the obtained polyamic acid solution has a solid content of 26wt%, an intrinsic viscosity of 2.49dL / g, and a dynamic viscosity of 35700 centipoise.

[0108] Comparative Example 4

[0109] This comparative example provides a polyamic acid solution, and its preparation steps are basically the same as those of Example 10, except that: in this comparative example, only 0.5726 g of pentamethylenediamine is added, and no triphosphoric acid is added. The obtained polyamic acid solution has a solid content of 15 wt%, an intrinsic viscosity of 2.17 dL / g, and a dynamic viscosity of 18100 centipoise.

[0110] Comparative Example 5

[0111] This comparative example provides a polyamic acid solution, and its preparation steps are basically the same as those in Example 5, except that: in this comparative example, only 0.0287 g of triphosphoric acid is added, and no pentamethylenediamine is added. The obtained polyamic acid solution has a solid content of 20 wt%, a characteristic viscosity of 2.25 dL / g, and a dynamic viscosity of 24850 centipoise.

[0112] Comparative Example 6

[0113] This comparative example provides a polyamic acid solution, and its preparation steps are basically the same as those in Example 5, except that: in this comparative example, only 0.1195 g of pentamethylenediamine is added, and no triphosphoric acid is added. The obtained polyamic acid solution has a solid content of 20 wt%, an intrinsic viscosity of 2.44 dL / g, and a dynamic viscosity of 28402 centipoise.

[0114] As can be seen from the above-mentioned Examples 1-10, the present invention uses a composition of pentamethylenediamine and polyacid as an auxiliary agent, which can reduce the dynamic viscosity of the polyamic acid solution, make the polyamic acid solution easy to store, improve its stability, and synthesize a polyamic acid solution with high stability and controllable viscosity. The polyamic acid solution can have a high solid content and has the advantages of not affecting the performance of subsequent materials and facilitating subsequent material processing. In Comparative Examples 1-6, either no auxiliary agent is added, or only one of pentamethylenediamine and polyacid in the auxiliary agent is added, and the dynamic viscosity and intrinsic viscosity of the polyamic acid solution prepared are significantly higher than those of Examples 1-10 of the present invention.

Claims

1. A method for preparing a polyamic acid solution, comprising the following steps: During the reaction of aromatic dianhydride and diamine, a combination of pentamethylenediamine and polyacid is added as an auxiliary agent.

2. The preparation method according to claim 1, wherein The preparation method of the polyamic acid solution comprises the following steps: (I) mixing a solvent, a diamine and an aromatic dianhydride; (II) reacting the mixed solution obtained in step (I) to obtain the polyamic acid solution; An auxiliary agent is added in step (I) or (II), wherein the auxiliary agent is a combination of pentamethylenediamine and polyacid.

3. The preparation method according to claim 1 or 2, wherein In the auxiliary agent, the polyacid includes pyrophosphoric acid and / or triphosphoric acid.

4. The preparation method according to claim 1 or 2, wherein: In the auxiliary agent, the mass ratio of the polyacid to pentamethylenediamine is (0.01-0.5):

1.

5. The preparation method according to claim 2, wherein: Based on 100% by mass of the solvent, the amount of pentamethylenediamine added in the auxiliary agent is 0.1-2% by mass.

6. The preparation method according to claim 2, wherein: The solvent includes an aprotic polar solvent; Preferably, the solvent comprises one or a combination of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide and hexamethylphosphoric triamide.

7. The preparation method according to claim 1 or 2, wherein: The diamine includes one or a combination of aromatic diamines and aliphatic diamines; Preferably, the diamine includes one or a combination of p-phenylenediamine, 4,4'-diaminodiphenyl ether, hydroquinone diether diamine, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylmethane, ethylenediamine, 1,6-hexanediamine and bisphenol A diether diamine.

8. The preparation method according to claim 1 or 2, wherein: The aromatic dianhydride includes one or a combination of the following: pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ketone tetracarboxylic dianhydride, triphenyl diether dianhydride, diphenyl ether dianhydride, diphenyl sulfide dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, hydroquinone diether dianhydride, hexafluoro dianhydride, resorcinol diether dianhydride and bisphenol A diether dianhydride.

9. The preparation method according to claim 1 or 2, wherein: The molar ratio of the diamine to the aromatic dianhydride is 1:(0.995-1.01).

10. The preparation method according to claim 1 or 2, wherein: The total mass of the diamine and the aromatic dianhydride accounts for 10-30% of the total mass of the reaction system.

11. The preparation method according to claim 2, wherein: The system temperature in steps (I) and (II) is -15 to 50°C.

12. The preparation method according to claim 2, wherein: The reaction time of step (II) is 1-10 hours.

13. A polyamic acid solution, which is prepared by the method for preparing a polyamic acid solution according to any one of claims 1 to 12; Preferably, the dynamic viscosity of the polyamic acid solution is 8000cp or less, more preferably 6000cp or less; Preferably, the solid content of the polyamic acid solution is greater than 10 wt %; Preferably, the intrinsic viscosity of the polyamic acid solution is 2.5 dL / g or less, more preferably 1.8 dL / g or less.

14. A raw material composition for preparing a polyamic acid solution, comprising a solvent, an auxiliary agent, and a diamine and an aromatic dianhydride, wherein the auxiliary agent is a composition of pentamethylenediamine and a polyacid; the raw material composition is used to prepare a polyamic acid solution using the preparation method described in any one of claims 1 to 12.

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