Production system of flame-retardant polyamide
By adopting the method of salt first and then in-situ polymerization in the polyamide production system, the uniform dispersion and efficient utilization of flame retardant in the polyamide is achieved, and the problems of poor flame retardant performance and complex process in the prior art are solved, and the mechanical properties and production efficiency of the material are improved.
Patent Information
- Application Number
- CN202421816792.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-30
- Publication Date
- 2025-06-17
- Estimated Expiration
- 2034-07-30
AI Technical Summary
The flame retardant properties of existing polyamides are poor, the amount of flame retardant is large and uneven, which damages the mechanical properties of the material. There are compatibility and color problems with polymer flame retardant modification, which are complicated steps, large equipment investment, and limited industrial applications.
A flame retardant polyamide production system is provided. By first forming a salt and then in-situ polymerization, dibasic acid, diamine, first flame retardant additive and second flame retardant additive are mixed in a salt kettle to obtain a premixed salt solution, and then polycondensation reaction is carried out in the polymerization kettle to achieve uniform dispersion and efficient utilization of the flame retardant.
The flame retardant addition amount is extremely small and uniformly dispersed, which improves the mechanical properties of polyamides, simplifies the process flow, reduces production costs, improves production efficiency, and can be produced in an industrial manner.
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Figure CN222984356U_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the technical field of polyamides, and particularly to a production system for flame-retardant polyamides. Background Art
[0002] Polyamide (PA, commonly known as nylon) has characteristics such as high mechanical strength, good thermal stability, and excellent solvent resistance, and plays an important role in the fields of machinery, transportation, electronics, aviation, etc. It is the engineering plastic with the most applications and the largest output in the world.
[0003] However, unmodified nylon has poor flame-retardant performance and will produce a dripping phenomenon during combustion, which is extremely likely to cause fire problems during use.
[0004] Currently, the modification of polyamide is blend flame-retardant modification and polymerization flame-retardant modification. Among them, for blend flame-retardant modification to achieve the required flame-retardant effect, the addition amount of the flame retardant is large, which is not conducive to uniform dispersion and will damage the mechanical properties of the material. Polymerization flame-retardant modification has problems of compatibility and color, complex steps, large equipment investment, and limited industrial application. Summary of the Utility Model
[0005] In view of the above problems, the present disclosure is proposed. The present disclosure provides a production system for flame-retardant polyamides, in which the addition amount of the flame retardant is extremely small and is uniformly dispersed in the polyamide, and the flame-retardant system has good stability.
[0006] According to one aspect of the present disclosure, there is provided a production system for flame-retardant polyamides, including: a dibasic acid storage tank, a diamine storage tank, a first flame-retardant auxiliary storage tank, a second flame-retardant auxiliary storage tank, a salt-forming kettle, and a polymerization kettle. The outlets of the dibasic acid storage tank, the diamine storage tank, the first flame-retardant auxiliary storage tank, and the second flame retardant storage tank are respectively communicated with the inlets of the salt-forming kettle, and the liquid outlet of the salt-forming kettle is communicated with the inlet of the polymerization kettle.
[0007] Compared with the prior art, in the production system of the flame-retardant polyamide provided by the present disclosure, first, deionized water, a dibasic acid, a diamine, a first flame-retardant additive solution, and a second flame-retardant additive solution are sequentially fed into a salification kettle for mixing, and stirred evenly to obtain a premixed salt solution. Then, the premixed salt solution is fed into a polymerization kettle, and the premixed salt solution undergoes a polycondensation reaction in the polymerization kettle to obtain the flame-retardant polyamide. During this salification process, the first flame-retardant additive and the second flame-retardant additive can be well dispersed in the diamine and the dibasic acid, improving the compatibility of the first flame-retardant additive and the second flame-retardant additive in the polymerization system, enabling the dispersion of the first flame-retardant additive and the second flame-retardant additive in the polymerization system to reach the nanoscale, further improving the utilization efficiency of the flame retardant, thereby reducing the amount of flame retardant added, saving costs, and providing the mechanical properties of the polyamide. Moreover, the flame-retardant polyamide is synthesized by the method of first salifying and then in-situ polymerizing, with a simple operation process, low production cost, high production efficiency, and can be industrially produced.
[0008] As can be seen from the above, the preparation method of the flame-retardant polyamide provided by the embodiments of the present disclosure improves the mechanical properties of the polyamide and reduces the process flow and process costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] By describing the embodiments of the present disclosure in more detail in conjunction with the accompanying drawings, the above and other objects, features, and advantages of the present disclosure will become more obvious. The accompanying drawings are used to provide a further understanding of the embodiments of the present disclosure, and constitute a part of the specification, and are used to explain the present disclosure together with the embodiments of the present disclosure, and do not constitute a limitation to the present disclosure. In the accompanying drawings, the same reference numerals generally represent the same components or steps.
[0010] Figure 1 It is a process flow diagram of the production system of the flame-retardant polyamide provided by the embodiments of the present disclosure.
[0011] REFERENCE SIGNS:
[0012] 100 - dibasic acid storage tank, 200 - diamine storage tank, 300 - first flame-retardant additive storage tank, 400 - second flame-retardant additive storage tank, 500 - salification kettle, 600 - polymerization kettle, 700 - water inlet pipe; 800 - concentration kettle, 900 - steam condenser, 1000 - waste liquid recovery tower, 1100 - granulation and drying unit, 1200 - packaging unit. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0013] In order to make the objectives, technical solutions, and advantages of the present disclosure more obvious, exemplary embodiments according to the present disclosure will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments of the present disclosure. It should be understood that the present disclosure is not limited by the exemplary embodiments described herein.
[0014] Polyamide is one of the five major engineering plastics and has a wide range of applications due to its outstanding characteristics such as wear resistance, light weight, and aging resistance. When using polyamide materials, good mechanical properties are required for the polyamide materials.
[0015] However, unmodified polyamide has poor flame retardancy. Its limiting oxygen index (LOI) does not exceed 23%, and the vertical burning test grade is V-2, still belonging to flammable materials. Moreover, dripping phenomenon occurs during combustion, and fire problems are extremely likely to be caused during use.
[0016] Currently, the method of introducing flame retardants into the polyamide matrix is usually adopted to carry out flame retardant modification on polyamide. According to different modification methods, the preparation methods of flame retardant polyamide can be divided into blending flame retardant modification and polymerization flame retardant modification. Among them, the blending flame retardant modification process is simple and is the main method for producing flame retardant nylon at present. However, in order to achieve the required flame retardant effect, the addition amount of flame retardant is large, which is not conducive to uniform dispersion and will damage the mechanical properties of the material. The polymerization method is to use the flame retardant as a reaction monomer to participate in the reaction and combine it onto the main chain or side chain of polyamide, so that polyamide itself contains flame retardant components, having the advantages of good stability, low toxicity, little influence on the use performance of the material, and long-lasting flame retardancy. However, there are still compatibility and color problems, and the steps are complex, the equipment investment is large, and the industrial application is limited.
[0017] Aiming at the above problems, the embodiments of the present disclosure provide a production system for flame retardant polyamide, with extremely small addition amount of flame retardant and uniform dispersion in polyamide, and good stability of the flame retardant system. It solves the problems in the prior art that the addition amount of flame retardant is large, which is not conducive to uniform dispersion and will damage the mechanical properties of the material.
[0018] Figure 1 The process flow chart of the production system for flame retardant polyamide provided by the embodiments of the present disclosure is shown. As Figure 1 shown, the production system for flame retardant polyamide of the embodiments of the present disclosure includes: a dibasic acid storage tank 100, a diamine storage tank 200, a first flame retardant auxiliary storage tank 300, a second flame retardant auxiliary storage tank 400, a salt-forming kettle 500, and a polymerization kettle 600. The outlets of the dibasic acid storage tank 100, the diamine storage tank 200, the first flame retardant auxiliary storage tank 300, and the second flame retardant auxiliary storage tank 400 are respectively communicated with the inlet of the salt-forming kettle 500, and the liquid outlet of the salt-forming kettle 500 is communicated with the inlet of the polymerization kettle 600.
[0019] During specific implementation, the dibasic acid storage tank 100, the diamine storage tank 200, the first flame retardant auxiliary storage tank 300, and the second flame retardant auxiliary storage tank 400 can be used to transport the dibasic acid, diamine solution, first flame retardant auxiliary solution, and second flame retardant auxiliary solution into the salt-forming kettle to complete the salt-forming process and obtain a premixed salt solution. Then, the premixed salt solution after salt formation is transported into the polymerization kettle 600 for polymerization.
[0020] In an implementable manner, the outlet of the dibasic acid storage tank 100 of the embodiments of the present disclosure is also communicated with the inlet of the first flame retardant additive storage tank 300, and the outlet of the diamine storage tank 200 is also communicated with the inlet of the second flame retardant additive storage tank 400.
[0021] During specific implementation, a part of the dibasic acid in the dibasic acid storage tank 100 can be first transported into the first flame retardant additive storage tank 300 and mixed with the first nitrogen-based flame retardant solution to obtain the first flame retardant additive solution. A part of the diamine solution in the diamine storage tank 200 is transported into the second flame retardant additive storage tank 400 and mixed with the second nitrogen-based flame retardant solution to obtain the second flame retardant additive solution.
[0022] Exemplarily, the production system of the embodiments of the present disclosure further includes a water inlet pipe 700, and the water inlet pipe 700 is communicated with the inlet of the salt-forming kettle 500, and deionized water can be transported into the salt-forming kettle by using the water inlet pipe.
[0023] In an optional manner, the production system of the embodiments of the present disclosure further includes a concentration kettle 800, the liquid outlet of the salt-forming kettle 500 is communicated with the inlet of the concentration kettle 800, and the liquid outlet of the concentration kettle 800 is communicated with the inlet of the polymerization kettle 600.
[0024] During specific implementation, after the salt-forming process in the salt-forming kettle 500 is completed, the obtained premixed salt solution can first enter the concentration kettle 800 for the first-stage concentration, and then enter the polymerization kettle 600 for the subsequent concentration process after the concentration is completed.
[0025] In an example, heating devices are provided in the salt-forming kettle, the concentration kettle, and the polymerization kettle of the embodiments of the present disclosure. The heating devices are used to heat each kettle so that the required temperature can be reached inside the kettle.
[0026] In an optional manner, the production system of the embodiments of the present disclosure further includes a steam condenser 900, the gas outlet of the concentration kettle 800 is communicated with the inlet of the steam condenser 900, and the gas outlet of the polymerization kettle 600 is communicated with the inlet of the steam condenser 900.
[0027] During specific implementation, the by-product gas generated during the concentration processes of the above-mentioned concentration kettle 800 and polymerization kettle 600 can be transported into the steam condenser 900 for condensation.
[0028] Exemplarily, the production system of the embodiments of the present disclosure further includes a waste liquid recovery tower 1000, and the liquid outlet of the steam condenser 900 is communicated with the inlet of the waste liquid recovery tower 1000. After the by-product gas is condensed in the steam condenser 900, it enters the waste liquid recovery tower 1000 for recovery.
[0029] In one example, the production system of the embodiments of the present disclosure further includes a granulation and drying unit 1100, and the liquid outlet of the polymerization kettle 600 is communicated with the inlet of the granulation and drying unit 1100. The flame-retardant polyamide coming out of the polymerization kettle 600 enters the granulation and drying unit 1100 for granulation and drying treatment, so that the flame-retardant polyamide with the target specifications can be obtained.
[0030] Exemplarily, the production system of the embodiments of the present disclosure further includes a packaging unit 1200, and the outlet of the granulation and drying unit 1100 is communicated with the inlet of the packaging unit 1200. Therefore, the above-mentioned flame-retardant polyamide after granulation and drying can enter the packaging unit for packaging to complete the entire production process.
[0031] The embodiments of the present disclosure provide a preparation method of flame-retardant polyamide, which can be used to prepare the flame-retardant polyamide of the embodiments of the present disclosure. The preparation method of the flame-retardant polyamide of the embodiments of the present disclosure includes:
[0032] Step 101: Sequentially mix deionized water, a dibasic acid, a diamine, a first flame retardant additive solution and a second flame retardant additive solution in a salt-forming kettle, and stir evenly to obtain a premixed salt solution. It should be understood that the diamine may include ethylenediamine, propylenediamine, hexamethylenediamine, p-phenylenediamine or other diamines, and the dibasic acid may include oxalic acid, adipic acid, glutamic acid, aspartic acid or other dibasic acids, which are not limited herein.
[0033] Exemplarily, the dibasic acid can be fed into the salt-forming kettle, heated to 70°C to 75°C and maintained for 1h to 2h. Preferably, it is heated to 70°C and maintained for 1.5h to 1.8h, and then the diamine solution, the first flame retardant additive solution and the second flame retardant additive solution are sequentially added into the salt-forming kettle and stirred evenly. A premixed salt solution is formed in the salt-forming kettle. Among them, the mass concentration of the diamine solution is 40% to 60%, preferably 45% to 55%.
[0034] During this salt-forming process, the first flame retardant additive and the second flame retardant additive can be well dispersed in the diamine and the dibasic acid, improving the compatibility of the first flame retardant additive and the second flame retardant additive in the polymerization system, enabling the dispersion of the first flame retardant additive and the second flame retardant additive in the polymerization system to reach the nanoscale, further improving the utilization efficiency of the flame retardant, thereby reducing the amount of flame retardant added, saving costs, and providing the mechanical properties of polyamide.
[0035] In one example, the pH value of the premixed salt solution in the kettle can be adjusted to 7 to 9 by using the diamine solution, and the pH value is preferably 7.5 to 8.5 to control the addition amount of the hexamethylenediamine solution.
[0036] Step 102: Perform a polycondensation reaction using the premixed salt solution to obtain a flame-retardant polyamide.
[0037] Exemplarily, transfer the premixed salt solution into the polymerization kettle, and the premixed salt solution can be directly concentrated first and then polymerized in the polymerization kettle. For example: purge and replace the polymerization kettle with nitrogen, and then concentrate the premixed salt solution multiple times. After concentration, adjust the heat transfer oil temperature of the jacket and internal coil in the polymerization kettle to 270°C to 290°C, preferably 275°C to 285°C, so that the temperature in the concentration kettle rises to 260°C to 280°C, preferably 265°C to 275°C, and use a vacuum pumping device to pump the inside of the kettle to a negative pressure of 8 kPA to 10 kPA, preferably 8.5 kPA to 9.5 kPA, and carry out negative pressure polymerization reaction to obtain flame-retardant polyamide.
[0038] In one example, the concentration process in the above-mentioned polymerization kettle may include: according to the heating requirement, adjust the heat transfer oil temperature of the jacket and internal coil in the polymerization kettle to 250°C to 270°C, preferably 255°C to 265°C, so that the temperature in the concentration kettle rises to 200°C to 240°C, preferably 210°C to 230°C, increase the pressure in the kettle, and after the pressure in the kettle reaches 1.7 MPa(G) to 2 MPa(G), preferably 1.75 MPa(G) to 1.95 MPa(G), exhaust gas and maintain the pressure in the kettle. The exhaust time is about 1 to 3 h until the concentration of the premixed salt solution in the polymerization kettle reaches about 80% to 90%. Then, continue to adjust the heat transfer oil temperature of the jacket and internal coil in the polymerization kettle to 285°C to 295°C, carry out depolymerization reaction while exhausting gas until it drops to normal pressure, which takes about 1 h to 3 h. The concentration process is completed.
[0039] The preparation method of the flame-retardant polyamide of the embodiments of the present disclosure synthesizes the flame-retardant polyamide by the method of first forming salt and then in-situ polymerization. The operation process is simple, the production cost is low, the production efficiency is high, and it can be industrially produced. Moreover, it can ensure the uniform dispersion of the flame-retardant additive even when the addition amount of the flame-retardant additive is extremely small. The flame-retardant polyamide system has good stability, the prepared finished product is environmentally friendly, and does not sacrifice other properties of the material.
[0040] In an implementable manner, the embodiments of the present disclosure can also be provided with a concentration kettle, and the concentration process can be carried out first in the concentration kettle and then in the polymerization kettle.
[0041] Exemplarily, when using the premixed salt to carry out polycondensation reaction to obtain flame-retardant polyamide, it specifically includes: first, under the protection of inert gas, concentrate the premixed salt solution multiple times, discharge the by-product gas, and obtain the concentrated premixed salt. Then, use the concentrated premixed salt to carry out polycondensation reaction to obtain flame-retardant polyamide.
[0042] In one example, the above-mentioned concentration process of the embodiments of the present disclosure may include three concentration processes. Among them, the first concentration process is to heat the premixed salt solution to 200°C to 240°C, increase the pressure to 1.7 MPa to 2 MPa, keep the temperature and pressure for 0.3 h to 3 h for the first concentration, and discharge the by-product gas. The second concentration process may be to heat the premixed salt solution after the first concentration to 200°C to 240°C again, increase the pressure to 1.7 MPa to 2 MPa, keep the temperature and pressure for 0.3 h to 3 h for the second concentration, and discharge the by-product gas. The third concentration process may be to continue heating the premixed salt solution after the second concentration to 260°C to 280°C, reduce it to normal pressure, and discharge the by-product gas again to obtain the concentrated premixed salt.
[0043] It can be understood that in the above three concentration processes, the first concentration process can be completed in a concentration kettle. For example: purging and replacing the concentration kettle with nitrogen, adjusting the heat transfer oil temperature of the jacket and internal coil in the concentration kettle to 250°C to 270°C according to the heating requirements, preferably 255°C to 265°C, so that the temperature in the concentration kettle rises to 200°C to 240°C, preferably 210°C to 230°C, increasing the pressure in the concentration kettle. After the pressure in the concentration kettle reaches 1.7 MPa(G) to 2 MPa(G), preferably 1.75 MPa to 1.95 MPa, exhaust the gas and maintain the pressure in the kettle. The exhaust time is about 0.3 h to 3 h, preferably keep the temperature and pressure for 0.5 h to 2.5 h. When the salt solution concentration in the concentration kettle reaches about 70% to 75%, the first-stage concentration is completed. The second concentration process can be completed in a polymerization kettle. For example: purging and replacing the concentration kettle with nitrogen, adjusting the heat transfer oil temperature of the jacket and internal coil in the polymerization kettle to 250°C to 270°C according to the heating requirements, preferably 255°C to 265°C, so that the temperature in the concentration kettle rises to 200°C to 240°C, preferably 210°C to 230°C, increasing the pressure in the concentration kettle. After the pressure in the concentration kettle reaches 1.7 MPa(G) to 2 MPa(G), preferably 1.75 MPa to 1.95 MPa, exhaust the gas and maintain the pressure in the kettle. The exhaust time is about 0 h to 1 h, preferably keep the temperature and pressure for 0 h to 0.5 h. When the salt solution concentration in the polymerization kettle reaches about 80% to 90%, the second-stage concentration is completed. The third concentration process can also be completed in the polymerization kettle. For example: after the second-stage concentration stage ends, adjust the heat transfer oil temperature of the jacket and internal coil in the polymerization kettle to 270°C to 290°C, preferably 275°C to 285°C, so that the temperature in the concentration kettle rises to 260°C to 280°C, preferably 265°C to 275°C, and exhaust the gas at the same time until it drops to normal pressure, which takes about 1 to 3 h to complete the third concentration process.
[0044] In practical applications, during the concentration process of the concentration kettle, after the first-stage concentration is completed, it is necessary to open the gas-phase connection line to slowly balance the pressures of the concentration kettle and the polymerization kettle, and then transfer the material to the polymerization kettle of the polymerization and gas-phase condensation unit.
[0045] In an implementable manner, the embodiments of the present disclosure use the concentrated premixed salt to carry out a polycondensation reaction to obtain a flame-retardant polyamide, including: First, under a vacuum condition of 8 kPa to 10 kPa and at a temperature of 260 °C to 280 °C, the concentrated premixed salt is polymerized to obtain a molten end polymer. Then, the molten end polymer is pelletized and dried to obtain the flame-retardant polyamide. Among them, the reaction temperature of the polycondensation reaction is preferably 265 °C to 275 °C, the reaction pressure is preferably 8.5 kPa to 9.5 kPa, and the reaction time is 0 h to 0.5 h.
[0046] In an optional manner, before mixing the diamine, dibasic acid, first flame retardant aid, second flame retardant aid and deionized water, it is necessary to first prepare the first flame retardant aid and the second flame retardant aid. The first flame retardant aid can be prepared using a nitrogen-based flame retardant and a dibasic acid. The second flame retardant aid can be prepared using a nitrogen-based flame retardant and a diamine.
[0047] It can be understood that the above nitrogen-based flame retardants can include one or two of melamine, melamine polyphosphate and other nitrogen-based flame retardants. The flame retardant can be used as a reaction monomer and polymerized onto the main chain or side chain of polyamide (such as nylon 66), so that nylon 66 itself contains flame retardant components and has permanent flame retardancy.
[0048] Exemplarily, deionized water and a nitrogen-based flame retardant can be first mixed, and then dibasic acid is added. After stirring evenly, the reaction is carried out at 90 °C to 120 °C for 1 h to 2 h, preferably 95 °C to 115 °C, 1.2 h to 1.8 h, to prepare the first flame retardant aid solution. The diamine can be prepared into a 40% w to 60% wt diamine solution using deionized water. Then, deionized water and a nitrogen-based flame retardant are mixed, and diamine is added. After stirring evenly, the reaction is carried out at 90 °C to 120 °C for 1 h to 2 h to prepare the second flame retardant aid solution.
[0049] In an optional manner, in the above first flame retardant aid, the mass ratio of the nitrogen-based flame retardant to the dibasic acid is (20 to 30):(20 to 30). In the above second flame retardant aid, the mass ratio of the nitrogen-based flame retardant to the diamine is (30 to 40):(10 to 20).
[0050] Exemplarily, in the premixed salt solution of the embodiments of the present disclosure, the mass ratio of diamine, diacid, the first flame retardant aid, the second flame retardant aid, and deionized water is (30.85 - 37.85):(18.93 - 24.93):(11.41 - 16.41):(3.87 - 6.87):(13.94 - 34.94). Therefore, by adding a small amount of flame retardant, the uniform dispersion of the flame retardant can be achieved. At the same time, the flame retardant system has good stability, low toxicity, and does not sacrifice other properties of the material.
[0051] To verify the effect of the flame-retardant polyamide provided by the embodiments of the present disclosure, the embodiments of the present disclosure are proved by comparing examples with comparative examples.
[0052] Example 1
[0053] The embodiments of the present disclosure provide a flame-retardant polyamide, and its preparation method includes the following steps:
[0054] The first step is to prepare a premixed salt solution: by weight, 11.41 parts of the first flame retardant aid solution (wherein, 0.78 part of the first flame retardant), 3.87 parts of the second flame retardant aid solution (wherein, 1.00 part of the second flame retardant), 30.85 parts of hexamethylenediamine solution, 18.93 parts of adipic acid, and 34.94 parts of deionized water are put into the salt-forming kettle, stirred evenly for 1 h to form salt, and a premixed salt solution is obtained.
[0055] The second step is to prepare the flame-retardant polyamide: transfer the premixed salt solution to the concentration kettle, purge and displace it with nitrogen, adjust the heat transfer oil temperature of the jacket and the inner coil, raise the temperature in the kettle to 220 °C, raise the pressure to 2 MPa(G), keep the temperature and pressure for 1.5 h, and then transfer the concentrated salt solution to the polymerization kettle; the polymerization kettle is reheated to 220 °C, the pressure is raised to 2 MPa(G), after keeping the temperature and pressure for 0.3 h, adjust the heat transfer oil temperature of the jacket and the inner coil, finally raise the temperature to 270 °C, reduce to atmospheric pressure, and slowly discharge the gas for 1 h; evacuate to 10 KPa and carry out polycondensation for 0.5 h and then discharge the material. After underwater pelletizing and drying, flame-retardant nylon 66 is obtained, and the flame retardancy is good.
[0056] Example 2
[0057] The embodiments of the present disclosure provide a flame-retardant polyamide, and its preparation method includes the following steps:
[0058] The first step is to prepare a premixed salt solution: by weight, 16.41 parts of the first flame retardant aid solution, 6.87 parts of the second flame retardant aid solution, 37.85 parts of hexamethylenediamine solution, 24.93 parts of adipic acid, and 13.94 parts of deionized water are put into the salt-forming kettle, stirred evenly for 1 h to form salt, and a premixed salt solution is obtained.
[0059] Step 2, preparing flame-retardant polyamide: Transfer the premixed salt solution to the concentration kettle, purge and displace it with nitrogen, adjust the heat transfer oil temperature of the jacket and the internal coil, heat up the kettle to 220 °C, increase the pressure to 2 MPa(G), keep the temperature and pressure for 1.5 h, and then transfer the concentrated salt solution to the polymerization kettle; Reheat the polymerization kettle to 220 °C, increase the pressure to 2 MPa(G), keep the temperature and pressure for 0.3 h, then adjust the heat transfer oil temperature of the jacket and the internal coil, finally heat up to 270 °C, reduce to atmospheric pressure, and slowly discharge the gas for 1 h; Evacuate to 10 KPa and then carry out polycondensation for 0.5 h before discharging. After underwater pelletizing and drying, flame-retardant nylon 66 is obtained, with good flame-retardant performance.
[0060] Example 3
[0061] An embodiment of the present disclosure provides a flame-retardant polyamide, and its preparation method includes the following steps:
[0062] Step 1, preparing a premixed salt solution: By weight, put 11.41 parts of the first flame-retardant auxiliary solution, 3.87 parts of the second flame-retardant auxiliary solution, 30.85 parts of hexamethylenediamine solution, 18.93 parts of adipic acid, and 34.94 parts of deionized water into the salt-forming kettle, stir evenly for 1 h to form salt, and obtain the premixed salt solution.
[0063] Step 2, preparing flame-retardant polyamide: Transfer the premixed salt solution to the concentration kettle, purge and displace it with nitrogen, adjust the heat transfer oil temperature of the jacket and the internal coil, heat up the kettle to 210 °C, increase the pressure to 1.7 MPa(G), keep the temperature and pressure for 1.5 h, and then transfer the concentrated salt solution to the polymerization kettle; Reheat the polymerization kettle to 210 °C, increase the pressure to 1.7 MPa(G), keep the temperature and pressure for 0.3 h, then adjust the heat transfer oil temperature of the jacket and the internal coil, finally heat up to 275 °C, reduce to atmospheric pressure, and slowly discharge the gas for 1 h; Evacuate to 10 KPa and then carry out polycondensation for 0.5 h before discharging. After underwater pelletizing and drying, flame-retardant nylon 66 is obtained, with good flame-retardant performance.
[0064] Example 4
[0065] An embodiment of the present disclosure provides a flame-retardant polyamide, and its preparation method includes the following steps:
[0066] Step 1, preparing a premixed salt solution: By weight, put 16.41 parts of the first flame-retardant auxiliary solution, 6.87 parts of the second flame-retardant auxiliary solution, 37.85 parts of hexamethylenediamine solution, 24.93 parts of adipic acid, and 13.94 parts of deionized water into the salt-forming kettle, stir evenly for 1 h to form salt, and obtain the premixed salt solution.
[0067] Step 2: Prepare flame-retardant polyamide: Transfer the premixed salt solution to the concentration kettle, purge and displace it with nitrogen, adjust the heat transfer oil temperature of the jacket and the inner coil, heat up the kettle to 210 °C, increase the pressure to 1.7 MPa (G), keep the temperature and pressure for 1.5 h, and then transfer the concentrated salt solution to the polymerization kettle; Reheat the polymerization kettle to 210 °C, increase the pressure to 1.7 MPa (G), keep the temperature and pressure for 0.3 h, then adjust the heat transfer oil temperature of the jacket and the inner coil, finally heat up to 270 °C, reduce to atmospheric pressure, and slowly discharge the gas for 1 h; Evacuate to 10 KPa and carry out polycondensation for 0.5 h before discharging. After underwater pelletizing and drying, flame-retardant nylon 66 is obtained, and it has good flame-retardant performance.
[0068] Example 5
[0069] An embodiment of the present disclosure provides a flame-retardant polyamide, and its preparation method includes the following steps:
[0070] Step 1: Prepare the premixed salt solution: By weight, put 16.41 parts of the first flame-retardant additive solution, 6.87 parts of the second flame-retardant additive solution, 37.85 parts of hexamethylenediamine solution, 24.93 parts of adipic acid, and 13.94 parts of deionized water into the salifying kettle, stir evenly for 1 h to form salt, and obtain the premixed salt solution.
[0071] Step 2: Prepare flame-retardant polyamide: Transfer the premixed salt solution to the concentration and polymerization kettle, purge and displace it with nitrogen, adjust the heat transfer oil temperature of the jacket and the inner coil, heat up the kettle to 220 °C, increase the pressure to 2 MPa (G), keep the temperature and pressure for 1.8 h, then adjust the heat transfer oil temperature of the jacket and the inner coil, finally heat up to 275 °C, reduce to atmospheric pressure, and slowly discharge the gas for 1 h; Evacuate to 10 KPa and carry out polycondensation for 0.3 h before discharging. After underwater pelletizing and drying, flame-retardant nylon 66 is obtained, and the flame-retardant performance of the sample is good.
[0072] Comparative Example
[0073] The comparative example of the present disclosure provides a flame-retardant polyamide. Compared with Example 1 of the present disclosure, the weight fractions of the first flame-retardant additive and the second flame-retardant additive added are the same, and its preparation method includes the following steps:
[0074] Step 1: Prepare the premixed salt solution: By weight, put 0.78 parts of the first flame-retardant additive, 1.00 parts of the second flame-retardant additive, 30.85 parts of hexamethylenediamine solution, 18.93 parts of adipic acid, and 34.94 parts of deionized water into the salifying kettle, stir evenly for 1 h to form salt, and obtain the premixed salt solution.
[0075] Step 2, prepare flame-retardant polyamide: Transfer the premixed salt solution to the concentrated polymerization kettle, purge and displace it with nitrogen, adjust the heat transfer oil temperature of the jacket and the internal coil, heat up the kettle to 220 °C, boost the pressure to 2 MPa(G), keep the temperature and pressure for 1.8 h, then adjust the heat transfer oil temperature of the jacket and the internal coil, finally heat up to 270 °C, reduce to atmospheric pressure, and slowly discharge the gas for 1 h; evacuate to 10 KPa and then carry out polycondensation for 0.5 h before discharging. After underwater pelletizing and drying, flame-retardant nylon 66 is obtained, and the flame-retardant performance of the sample is good.
[0076] The present disclosure tests the limiting oxygen index and UL 94 of the flame-retardant nylon 66 prepared in the examples and comparative examples. The test methods are as follows:
[0077] Limiting oxygen index (LOI) test: Refer to the standard ASTM D2863 2010 "Determination of Flammability Characteristics of Plastics by the Oxygen Index Method", and measure it at room temperature using a limiting oxygen index tester. The sample bar specifications are: 80 mm * 10 mm * 4 mm.
[0078] UL 94 vertical burning test: Refer to the standard DIN IEC 60695 11 10 20 "Plastics - Methods of Test for Flammability - Horizontal and Vertical Methods", and measure it at room temperature using a CFZ 5 vertical burning tester. The sample bar specifications are: 125 mm * 3.2 mm * 3.2 mm.
[0079] In the examples and comparative examples of the present disclosure, in Examples 1 to 4, the salifying kettle, concentration kettle, and polymerization kettle are all operated independently, and both the first flame-retardant aid and the second flame-retardant aid are first prepared into salt solutions and then participate in salification. In Example 5, the salifying kettle and the concentrated prepolymerization kettle are operated independently, and both the first flame-retardant aid and the second flame-retardant aid are first prepared into salt solutions and then participate in salification. The weight fractions of the first flame-retardant aid and the second flame-retardant aid added in the comparative example are the same as those in Example 1 of the present disclosure. The salifying kettle and the concentrated prepolymerization kettle are operated independently, and the first flame-retardant aid and the second flame-retardant aid directly participate in salification in the salifying kettle. The test results of Examples 1 to 5 and the comparative example of the present disclosure are shown in the following table:
[0080]
[0081] As can be seen from the above table, the oxygen indices of Examples 1 to 5 of the present disclosure are significantly greater than those of the comparative examples. After the flame retardant nylon samples of Examples 1 to 5 were subjected to two 10-second combustion tests, the flame could be extinguished within 10 seconds. Therefore, the flame retardant nylon prepared in Examples 1 to 5 of the present disclosure has good flame retardancy. In terms of the reaction time of a single batch, by operating the salifying kettle, concentration kettle, and polymerization kettle independently, and preparing the first flame retardant aid and the second flame retardant aid into salt solutions first and then participating in salification, compared with directly participating in salification in the salifying kettle, the reaction time is greatly reduced, and the production capacity can be increased by up to twice, greatly improving the production efficiency.
[0082] As described above, the flame retardant polyamide and its preparation method according to the embodiments of the present disclosure have been described with reference to the accompanying drawings. The flame retardant polyamide is synthesized by a method of salifying first and then in-situ polymerization. The operation process is simple, the production cost is low, the production efficiency is high, and it can be industrially produced. Moreover, even when the addition amount of the flame retardant aid is extremely small, it can ensure that the flame retardant aid is evenly dispersed. The flame retardant polyamide system has good stability, the prepared finished product is environmentally friendly, and does not sacrifice other properties of the material.
[0083] The basic principles of the present disclosure have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, advantages, effects, etc. mentioned in the present disclosure are only examples and not limitations. It cannot be considered that these advantages, advantages, effects, etc. are essential for each embodiment of the present disclosure. In addition, the above-mentioned specific details are only for the purpose of illustration and easy understanding, rather than limitations. The above details do not limit the present disclosure to necessarily adopt the above specific details to implement.
[0084] The block diagrams of the devices, apparatuses, equipment, and systems involved in the present disclosure are only illustrative examples and do not intend to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open-ended words, meaning "including but not limited to", and can be used interchangeably with each other. The words "or" and "and" used herein refer to the word "and / or", and can be used interchangeably with each other, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to", and can be used interchangeably with each other.
[0085] In addition, as used herein, the "or" used in the enumeration of items starting with "at least one" indicates a separate enumeration. For example, the enumeration of "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). In addition, the term "exemplary" does not mean that the described examples are preferred or better than other examples.
[0086] It should also be noted that in the systems and methods of the present disclosure, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent solutions of the present disclosure.
[0087] Various changes, substitutions, and alterations to the techniques described herein can be made without departing from the techniques taught by the appended claims. In addition, the scope of the claims of the present disclosure is not limited to the specific aspects of the processes, machines, manufactures, compositions of events, means, methods, and acts described above. Current or later-developed processes, machines, manufactures, compositions of events, means, methods, or acts that perform substantially the same function or achieve substantially the same result as the corresponding aspects described herein can be utilized. Accordingly, the appended claims include such processes, machines, manufactures, compositions of events, means, methods, or acts within their scope.
[0088] The foregoing description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the aspects shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
[0089] The foregoing description has been presented for purposes of illustration and description. In addition, this description is not intended to limit the embodiments of the present disclosure to the forms disclosed herein. Although numerous example aspects and embodiments have been discussed above, those skilled in the art will recognize some of their variations, modifications, alterations, additions, and subcombinations.
Claims
1. A flame retardant polyamide production system, characterized in that: include: A dibasic acid storage tank, a diamine storage tank, a first flame retardant auxiliary storage tank, a second flame retardant auxiliary storage tank, a salt forming kettle and a polymerization kettle, wherein the outlets of the dibasic acid storage tank, the diamine storage tank, the first flame retardant auxiliary storage tank and the second flame retardant auxiliary storage tank are respectively connected to the inlet of the salt forming kettle, and the liquid outlet of the salt forming kettle is connected to the inlet of the polymerization kettle.
2. The flame retardant polyamide production system according to claim 1, characterized in that: The outlet of the dibasic acid storage tank is also communicated with the inlet of the first flame retardant auxiliary agent storage tank.
3. The flame retardant polyamide production system according to claim 1, characterized in that: The outlet of the diamine storage tank is also communicated with the inlet of the second flame retardant auxiliary agent storage tank.
4. The flame retardant polyamide production system according to claim 1, characterized in that: The production system also includes a water inlet pipe, which is connected to the inlet of the salt-forming kettle.
5. The flame retardant polyamide production system according to claim 1, characterized in that: The production system further comprises a concentration kettle, wherein the liquid outlet of the salt-forming kettle is communicated with the inlet of the concentration kettle, and the liquid outlet of the concentration kettle is communicated with the inlet of the polymerization kettle.
6. The flame retardant polyamide production system according to claim 5, characterized in that: The salt-forming kettle, the concentration kettle and the polymerization kettle are all provided with heating devices.
7. The flame retardant polyamide production system according to claim 5, characterized in that: The production system further comprises a steam condenser, the gas outlet of the concentration kettle is communicated with the inlet of the steam condenser, and the gas outlet of the polymerization kettle is communicated with the inlet of the steam condenser.
8. The flame retardant polyamide production system according to claim 7, characterized in that: The production system further comprises a waste liquid recovery tower, and the liquid outlet of the steam condenser is communicated with the inlet of the waste liquid recovery tower.
9. The flame retardant polyamide production system according to claim 1, characterized in that: The production system further comprises a granulation and drying unit, and the liquid outlet of the polymerization kettle is connected to the inlet of the granulation and drying unit.
10. The flame retardant polyamide production system according to claim 9, characterized in that: The production system further comprises a packaging unit, and the outlet of the granulation and drying unit is communicated with the inlet of the packaging unit.