Controllable low-oxygen-content polyamide acid synthesis device and synthesis method

Abstract

The invention discloses a controllable low-oxygen-content polyamide acid synthesis device and a synthesis method. The structure of the polyamide acid synthesis device is as follows: a nitrogen injection pipeline I and a pressure gauge are arranged on a solvent tank, the nitrogen injection pipeline I extends into the bottom of the solvent tank and is connected with a gas distributor I, the top of the solvent tank is connected with a tail gas absorption device through a pipeline I, and an oxygen detector I and a valve I are arranged on the pipeline I; the bottom of the solvent tank is connected with the top of the synthesis kettle through a pipeline II; a solvent pump and a liquid flowmeter are arranged on the pipeline II; the top of the synthesis kettle is connected with a nitrogen injection pipeline II and a tail gas discharge pipeline, a gas flowmeter and a valve II are arranged on the nitrogen injection pipeline II, and an oxygen detector II and a valve III are arranged on the tail gas discharge pipeline. According to the synthesis device and method, the change of the oxygen content in the whole synthesis process can be monitored in real time, reaction control is facilitated, and batch stability is guaranteed.

Description

Technical Field

[0001] The present invention relates to a device and a synthesis method for synthesizing polyamic acid with a controllable low oxygen content, belonging to the field of polymer synthesis. Background Art

[0002] Polyimide (PI) is an aromatic heterocyclic polymer compound with an imide group link in its molecular structure. It is one of the engineering plastics with the best heat resistance at present. Due to its excellent properties, it is widely used in the fields of aviation, aerospace, microelectronics, nanotechnology, liquid crystal, laser, etc. According to different usage scenarios, PI can also be divided into various types, including engineering plastics, fibers, photosensitive PI, foam materials, coatings, adhesives, films, aerogels, composite materials, etc.

[0003] During the synthesis process of polyimide precursor polyamic acid, the oxygen content in the reaction system will affect the color of the polymer, and may further affect its mechanical properties, thermal properties, etc. At present, in a conventional synthesis kettle, nitrogen is generally only introduced into the upper end of the kettle, and the exhaust is also at the upper end of the kettle cover. When nitrogen enters, it can only displace the oxygen in the space above the liquid level in the kettle. And it is easy to short-circuit and directly discharge from the upper exhaust port nearby, resulting in poor oxygen replacement effect for the solvent in the kettle.

[0004] In addition, generally an open feeding method is adopted, and the introduction of external moisture during the feeding process will cause instability in the polymer viscosity between batches, resulting in a decrease in the qualified rate and poor economic benefits. Summary of the Invention

[0005] The purpose of the present invention is to provide a device and a synthesis method for synthesizing polyamic acid with a controllable low oxygen content, which can make the reaction system in a low oxygen environment during the synthesis process, effectively control the color; at the same time, it can realize closed operation, effectively avoid the introduction of moisture in the environment, and ensure the stability of the viscosity between batches.

[0006] The device for synthesizing polyamic acid with a controllable low oxygen content provided by the present invention includes a solvent tank and a synthesis kettle;

[0007] A nitrogen injection pipeline I and a pressure gauge are provided on the solvent tank. The nitrogen injection pipeline I extends to the bottom of the solvent tank and is connected to a gas distributor I. The top of the solvent tank is connected to a tail gas absorption device through a pipeline I. An oxygen detector I and a valve I are provided on the pipeline I. The bottom of the solvent tank is connected to the top of the synthesis kettle through a pipeline II. A solvent pump and a liquid flowmeter are provided on the pipeline II;

[0008] The top of the synthesis kettle is connected to a nitrogen injection pipeline II and a tail gas discharge pipeline. A gas flowmeter and a valve II are provided on the nitrogen injection pipeline II. An oxygen detector II and a valve III are provided on the tail gas discharge pipeline. The other end of the oxygen detector II is connected to the tail gas absorption device;

[0009] A temperature sensor, a pressure gauge and a feeding valve are provided at the top of the synthesis kettle.

[0010] In the above polyamic acid synthesis device, the nitrogen injection pipeline II extends to the bottom of the synthesis kettle and is connected to the gas distributor II.

[0011] In the above polyamic acid synthesis device, both the gas distributor I and the gas distributor II are annular round pipes, and a number of downward orifices are arranged to ensure sufficient replacement of oxygen in the kettle.

[0012] In the above polyamic acid synthesis device, the feeding valve is an αβ valve.

[0013] In the above polyamic acid synthesis device, a safety valve is provided at the top of the solvent tank. When nitrogen protection is carried out, it can prevent the pressure in the solvent tank from being too high due to excessive opening of nitrogen, thus avoiding potential safety hazards.

[0014] In the above polyamic acid synthesis device, the solvent pump is a pneumatic diaphragm pump, and its internal material is PFA, which is not easy to contaminate the solvent.

[0015] When synthesizing polyamic acid with low oxygen content by using the synthesis device of the present invention, the following steps can be carried out:

[0016] S1. Turn on the oxygen detector I and the valve I, and inject nitrogen into the solvent tank through the nitrogen injection pipeline I to replace the solvent in the solvent tank; until the test value of the oxygen detector I shows that the oxygen content < 5%, preferably < 2%, then turn off the oxygen detector I and the valve I;

[0017] S2. Turn on the oxygen detector II and the valve III, and inject nitrogen into the synthesis kettle through the nitrogen injection pipeline II;

[0018] S3. When the test value of the oxygen detector II shows < 5%, preferably < 2%, turn on the solvent pump and inject the solvent into the synthesis kettle;

[0019] S4. Add diamine powder into the synthesis kettle, heat and stir until it becomes clear;

[0020] S5. Add dianhydride powder into the synthesis kettle and carry out a synthesis reaction under stirring.

[0021] During the synthesis process, record the detected values of the oxygen content throughout the process to ensure that the oxygen content < 2% throughout the process; after the reaction is completed, test the water content, viscosity and color.

[0022] The diamines applicable to the method of the present invention include at least one of p-phenylenediamine, o-phenylenediamine, m-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl methane, 4,4'-diaminodiphenyl methane, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, benzidine, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-diethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-diethyl-4,4'-diaminobiphenyl, 2,2',3,3'-tetramethyl-4,4'-diaminobiphenyl, 2,2',3,3'-tetramethyl-4,4'-diaminobiphenyl, 1,4-bis(4'-aminophenoxy)benzene, 1,3-bis(4'-aminophenoxy))benzene, 1,3-bis(3'-aminophenoxy)benzene, 1,5-naphthalenediamine, 2,6-naphthalenediamine, bis(3-aminophenoxyphenyl) sulfone, bis(4-aminophenoxy)biphenyl, bis{4-(4-aminophenoxy)phenyl} ether, 1,3-bis(2-trifluoromethyl-4-aminophenoxy)benzene, 1,4-bis(2-trifluoromethyl-4-aminophenoxy)benzene (6FAPB), 4,4'-bis(2-trifluoromethyl-4-aminophenoxy)biphenyl (6FBAB), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB), 2,2-bis[4-(2-trifluoromethyl-4-aminophenoxy)phenyl]propane, 2,2'-bis(trifluoromethoxy)-4,4'-diaminobiphenyl (TFDOB), 3-trifluoromethyl-4,4'-diaminodiphenyl ether (3FODA), 3,3'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether (6FODA), 2,2'-bis(trifluoromethoxy)-5,5'-diaminobiphenyl, 3,3'-bis(trifluoromethyl)-5,5'-diaminobiphenyl, 3,3'-bis(trifluoromethyl)-5,5'-diaminodiphenyl ether, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis(4-aminophenoxybenzene)hexafluoropropane, 3-trifluoromethyl-m-phenylenediamine, tetrafluoro-p-phenylenediamine, tetrafluoro-m-phenylenediamine, 4,4'-diaminooctafluorobiphenyl, 4,4'-diaminooctafluorodiphenyl ether, and 4,4'-diaminooctafluorodiphenyl sulfide.

[0023] The dianhydrides applicable to the method of the present invention include at least one of 4,4'-oxydiphthalic anhydride, 3,4'-oxydiphthalic anhydride, pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,2’,3,3’-biphenyltetracarboxylic dianhydride, 4,4'-phenylenedioxydiphthalic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 3,3',4,4'-diphenylmethanetetracarboxylic dianhydride, 2,2',3,3'-diphenylmethanetetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, hydrogenated pyromellitic dianhydride, 2,3,5-tricarboxycyclopentaneacetic dianhydride, hydrogenated phthalic anhydride; specifically, it can be 4,4'-oxydiphthalic anhydride;

[0024] The present invention has the following beneficial effects:

[0025] (1) The solvent tank is sealed and protected by nitrogen. Nitrogen can fully displace the oxygen in the solvent through the gas distributor at the bottom, ensuring a low oxygen content in the solvent.

[0026] (2) The solvent is transported through pipelines, and the solid powder is added by an αβ valve. The entire feeding process is operated in a closed manner, effectively avoiding the introduction of external moisture.

[0027] (3) The synthesis kettle is sealed and protected by nitrogen. Nitrogen enters from the lower end inside the kettle body through the distributor and is evenly distributed, which can effectively displace the oxygen in the kettle and ensure a low oxygen content during the synthesis process.

[0028] (4) The change in the oxygen content during the entire synthesis process can be monitored in real time, which is beneficial for the control of the reaction and ensures batch stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of the polyamic acid synthesis device with controllable low oxygen content of the present invention.

[0030] Figure 2 is a schematic structural diagram of the gas distributor in the polyamic acid synthesis device with controllable low oxygen content of the present invention.

[0031] Figure 3 is a schematic structural diagram of a conventional synthesis kettle in the prior art.

[0032] The marks in the figure are as follows:

[0033] 1. Solvent tank; 2. Gas distributors I and II; 3. Nitrogen injection pipeline I; 4. Safety valve; 5. Pressure gauge; 6. Oxygen detectors I and II; 7. Valve I; 8. Solvent pump; 9. Liquid flowmeter; 10. Gas flowmeter; 11. Temperature sensor; 12. αβ valve; 13. Tail gas treatment device; 14. High and low temperature circulation all-in-one machine. Specific embodiments

[0034] In the following examples, the experimental methods used are all conventional methods unless otherwise specified.

[0035] In the following examples, the materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified.

[0036] In the following examples, the various test methods are as follows:

[0037] Water content test: Test using Mettler C20S.

[0038] Viscosity test: Use Brookfield DV2TRVCJ0 cone-plate viscometer from the United States, and select rotor 52#.

[0039] Color test: Compare using Gardner colorimetric standard solution (No. 1-18). Use the closest label as the color value.

[0040] As Figure 1 shown, it is a schematic structural diagram of a polyamic acid synthesis device with controllable low oxygen content provided by the present invention, including a solvent tank 1 and a synthesis kettle. The solvent tank 1 is provided with a nitrogen injection pipeline I 3 and a pressure gauge 5. The nitrogen injection pipeline I 3 extends to the bottom of the solvent tank 1 and is connected to the gas distributor 2. The top of the solvent tank 1 is connected to the tail gas absorption device 13 through pipeline I. Pipeline I is provided with an oxygen detector I 6 and a valve I 7. The bottom of the solvent tank 1 is connected to the top of the synthesis kettle through pipeline II. Pipeline II is provided with a solvent pump 8 and a liquid flowmeter 9. The top of the synthesis kettle is connected to a nitrogen injection pipeline II 3 and a tail gas discharge pipeline. The nitrogen injection pipeline II 3 is provided with a gas flowmeter 10 and a valve II, and it extends to the bottom of the synthesis kettle and is connected to the gas distributor II 2. The tail gas discharge pipeline is provided with an oxygen detector II 6 and a valve III. The other end of the oxygen detector II 6 is connected to the tail gas absorption device 13. The top of the synthesis kettle is also provided with a temperature sensor 11, a pressure gauge 5 and an αβ valve 12.

[0041] In the polyamic acid synthesis device of the present invention, both the gas distributor I and the gas distributor II are annular circular pipes, and a number of downward holes are arranged, which can ensure sufficient replacement of oxygen in the kettle, as Figure 2 shown.

[0042] In the polyamic acid synthesis device of the present invention, a safety valve 4 is provided at the top of the solvent tank 1. When nitrogen protection is carried out, it can prevent the pressure in the solvent tank 1 from being too high due to excessive opening of nitrogen, thus avoiding potential safety hazards.

[0043] In the polyamic acid synthesis device of the present invention, the solvent pump 8 is a pneumatic diaphragm pump, and its internal material is PFA, which is not easy to contaminate the solvent.

[0044] Example 1

[0045] Using Figure 1 the shown device for experiments, taking a 10L scale synthesis kettle as an example, the normal feeding operation steps are as follows:

[0046] (1) Open the oxygen detector Ⅰ6 and the rear valve Ⅰ7 connected to the upper end of the solvent tank 1.

[0047] (2) Slowly open the nitrogen valve at the upper end of the solvent tank 1. Nitrogen is introduced into the bottom of the solvent tank 1 through the gas distributor Ⅰ2 to displace the oxygen in the solvent. The gas enters the oxygen detector Ⅰ6 through the upper pipeline and then enters the tail gas absorption device.

[0048] (3) Wait until the oxygen content detected by the oxygen detector Ⅰ6 shows less than 2%, and then close the rear valve Ⅰ7 of the oxygen detector.

[0049] (4) Close the nitrogen valve at the upper end of the solvent tank 1. The solvent replacement is completed.

[0050] (5) Open the oxygen detector Ⅱ6 and the rear valve of the synthesis kettle.

[0051] (6) Open the nitrogen pipeline valve of the 10L synthesis kettle, adjust the nitrogen flow rate, and make the value shown on the gas flow meter 10 stable at 300 - 400 ml / min. Nitrogen is evenly introduced into the synthesis kettle through the gas distributor Ⅱ2.

[0052] (7) Observe the oxygen detector Ⅱ6. Initially, the oxygen content shows about 21%. As nitrogen is introduced, oxygen at the bottom is displaced, and the value shown on the oxygen detector gradually decreases. After about 60 minutes, the oxygen test value is less than 2%.

[0053] (8) Open the solvent pump 8, measure through the liquid flow meter 9, and add 5.883L of the solvent N-methylpyrrolidone into the synthesis kettle, and start the stirring of the synthesis kettle. At this time, it can be clearly seen that the bubbles formed by nitrogen through the distributor 2 in the solvent N-methylpyrrolidone.

[0054] (9) Add 270.35g of p-phenylenediamine using the αβ valve 12, start the high and low temperature circulation all-in-one machine 14, and set the temperature to 25°C. Stir until the p-phenylenediamine is completely dissolved and clarified.

[0055] (10) Then, another αβ valve 12 is used to add 767.79 g of 4,4'-oxybisphthalic anhydride for the synthesis reaction.

[0056] (11) Under the condition of 25 °C, continuously stir for 8 - 12 h, and record the oxygen content every 1 h.

[0057] (12) After the reaction is completed, test the water content, viscosity and color.

[0058] (13) Close the nitrogen inlet valve and the tail gas evacuation valve.

[0059] (14) Discharge the material and fill it.

[0060] Example 2 - 3:

[0061] Completely repeat Example 1, record the oxygen content in the synthesis stage, and test the viscosity and color, as shown in Table 1 and Table 2.

[0062] Comparative Example 1,

[0063] Using Figure 3 the shown device for the experiment, taking a 10 L scale synthesis kettle as an example, the normal feeding operation steps are as follows:

[0064] (1) Open the nitrogen pipeline valve of the 10 L synthesis kettle, adjust the nitrogen flow rate, and make the display value of the gas flowmeter stable at 300 - 400 ml / min, and introduce it into the synthesis kettle.

[0065] (2) Observe the oxygen detector, and the initial display shows that the oxygen content is about 21%. As nitrogen is introduced, the display value of the oxygen detector gradually decreases. After about 100 min, the oxygen test value < 2%.

[0066] (3) Weigh 5.883 L of the solvent N - methylpyrrolidone and add it to the synthesis kettle from the charging port on the kettle cover, and start the stirring of the synthesis kettle.

[0067] (4) Weigh 270.35 g of p - phenylenediamine and add it to the synthesis kettle from the charging port on the kettle cover, start the high - low temperature circulation all - in - one machine, and set it at 25 °C. Stir until the p - phenylenediamine is completely dissolved and clarified.

[0068] (5) Weigh 767.79 g of 4,4'-oxybisphthalic anhydride and add it to the synthesis kettle from the charging port on the kettle cover for the synthesis reaction.

[0069] (6) Under the condition of 25 °C, continuously stir for 8 - 12 h, and record the oxygen content every 1 h.

[0070] (7) After the reaction is completed, test the water content, viscosity and color.

[0071] (8) Close the nitrogen inlet valve and the tail gas evacuation valve.

[0072] (9) Discharging and filling.

[0073] Comparative Example 2-3:

[0074] Completely repeat Comparative Example 1, record the oxygen content in the synthesis stage, and test the viscosity and color, as shown in Table 1 and Table 2.

[0075] Table 1 Test values of oxygen content during the synthesis of examples and comparative examples

[0076]

[0077] Table 2 Comparison of test results of examples and comparative examples

[0078] Test Number Water Content Viscosity (cp) Color Example 1 0.033％ 11650 9 Example 2 0.036％ 11365 9 Example 3 0.035％ 11596 9 Comparative Example 1 0.066％ 10847 10 Comparative Example 2 0.075％ 9239 12 Comparative Example 3 0.071％ 9675 11

[0079] Note:

[0080] 1. The timing of the synthesis process starts from the addition of 4,4'-oxydiphthalic anhydride. 0 h represents the oxygen content measured just after the addition of 4,4'-oxydiphthalic anhydride.

[0081] 2. In the comparative examples, with the addition of solvents and materials, external air will be introduced. After the feeding is completed, the oxygen content rises to about 10%, and then it will slowly decrease again with the introduction of nitrogen.

[0082] From the data in the above two tables, it can be seen that the controllable low-oxygen-content polyamic acid synthesis device and method provided by the present invention can keep the reaction system in a low-oxygen environment during the synthesis process, effectively control the color; at the same time, it can achieve closed operation, effectively avoid the introduction of moisture in the environment, and ensure the stability of viscosity between batches.

Claims

1. A polyamic acid synthesis device with controllable low oxygen content, comprising a solvent tank and a synthesis kettle; The solvent tank is provided with a nitrogen injection pipeline I and a pressure gauge. The nitrogen injection pipeline I extends to the bottom of the solvent tank and is connected to a gas distributor I. The top of the solvent tank is connected to a tail gas absorption device through pipeline I. An oxygen detector I and a valve I are provided on pipeline I. The bottom of the solvent tank is connected to the top of the synthesis kettle through pipeline II. A solvent pump and a liquid flowmeter are provided on pipeline II; The top of the synthesis kettle is connected to a nitrogen injection pipeline II and a tail gas discharge pipeline. A gas flowmeter and a valve II are provided on the nitrogen injection pipeline II. An oxygen detector II and a valve III are provided on the tail gas discharge pipeline. The other end of the oxygen detector II is connected to the tail gas absorption device; The top of the synthesis kettle is provided with a temperature sensor, a pressure gauge and a feeding valve.

2. The polyamic acid synthesis device according to claim 1, wherein: The nitrogen injection pipeline II extends into the bottom of the synthesis kettle and is connected to the gas distributor II.

3. The polyamic acid synthesis device according to claim 2, wherein: Both the gas distributor I and the gas distributor II are annular circular pipes, with a number of downward orifices arranged.

4. The polyamic acid synthesis device according to any one of claims 1-3, wherein: The feeding valve is an αβ valve.

5. The polyamic acid synthesis device according to any one of claims 1-4, wherein: A safety valve is provided at the top of the solvent tank.

6. The polyamic acid synthesis device according to any one of claims 1-5, wherein: The solvent pump is a pneumatic diaphragm pump.

7. Application of the polyamic acid synthesis device according to any one of claims 1-5 in the synthesis of polyamic acid.

8. A method for synthesizing polyamic acid with low oxygen content, comprising the following steps carried out in the polyamic acid synthesis device according to any one of claims 1-5: S1. Turn on the oxygen detector I and the valve I, inject nitrogen into the solvent tank through the nitrogen injection pipeline I to displace the solvent in the solvent tank; until the test value of the oxygen detector I shows that the oxygen content < 5%, turn off the oxygen detector I and the valve I; S2. Turn on the oxygen detector II and the valve III, inject nitrogen into the synthesis kettle through the nitrogen injection pipeline II; S3. When the test value of the oxygen detector II shows < 5%, turn on the solvent pump and inject the solvent into the synthesis kettle; S4. Add diamine powder to the synthesis kettle, heat and stir until it becomes clear; S5. Add the dianhydride powder to the synthesis kettle and carry out the synthesis reaction under stirring.

9. A polyamic acid with a low oxygen content prepared by the method according to claim 8.

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