Large-capacity semi-dull nylon 66 resin continuous polymerization device for civil filaments and production process

Abstract

The invention relates to a large-capacity semi-dull nylon 66 resin continuous polymerization device for civil filaments and a production process, and through a whole-process continuous design (salification-concentration-polymerization-pelletizing) and an intelligent regulation and control system, the production efficiency and the product consistency are remarkably improved. According to the process, high-efficiency production is realized, and meanwhile, the product quality and the functional applicability are greatly improved through innovative structural design; the dispersity of TiO2 master batches in resin is effectively improved through high-shear mixing of a screw system, so that the spinnability is further improved; the continuous process supports the flexible adaptation of the antioxidant and the extinction master batch, reduces the waste of raw materials, lowers the comprehensive production cost, and obviously enhances the market competitiveness.

Description

Technical Field

[0001] This invention relates to the field of nylon resin processing equipment technology, specifically to a large-capacity continuous polymerization device and production process for semi-dull nylon 66 resin for civilian use. Background Technology

[0002] Nylon (PA) is a polymer with an amide backbone in its macromolecular backbone. Nylon 66 (polyhexamethylene adipamide), as the leading engineering plastic, is widely used in civilian textiles, aerospace, automotive manufacturing, and medical devices due to its excellent properties such as high strength, heat resistance, abrasion resistance, and fatigue resistance. Especially in the civilian textile sector, where high requirements exist for moisture absorption, abrasion resistance, and surface gloss, semi-matte finishing is necessary to improve the fiber's soft texture and antistatic properties, meeting the demands of high-end textiles. Its excellent overall performance makes it a highly commercially viable material.

[0003] However, the traditional production process of semi-dull nylon 66 resin for civilian use generally employs batch polymerization reactors, which suffers from low capacity, high energy consumption, and uneven molecular weight distribution, making it difficult to meet the demands of the civilian nylon market for high stability, low cost, and large-scale continuous production. While current continuous polymerization technology can improve production efficiency, it still faces multiple challenges in the industrial application of nylon 66: First, the real-time control precision of monomer conversion rate and by-products (such as moisture and oligomers) during continuous polymerization is insufficient, easily leading to product viscosity fluctuations and affecting spinning uniformity; second, semi-dull modification requires uniform dispersion of matting agents (such as titanium dioxide) during the polymerization stage, but traditional static mixers struggle to achieve stable dispersion of nanoparticles in a continuous system, easily causing fiber surface defects; third, the thermodynamic balance control of large-capacity devices is complex, with a wide distribution of melt residence time, restricting batch-to-batch product consistency. Furthermore, with increasingly stringent environmental regulations and growing demand for differentiated fibers from downstream industries, developing a continuous polymerization process that combines high efficiency, energy saving, high stability, and precise modification has become an urgent industry need.

[0004] This patent addresses the aforementioned technical pain points by proposing an innovative large-capacity continuous polymerization device and process. It aims to achieve efficient and continuous production of semi-dull nylon 66 resin for civilian use by optimizing reactor structure design, improving the dispersion mechanism of matting agent, and implementing intelligent process control. At the same time, it ensures the uniformity of semi-dull performance, providing reliable technical support for the high-end civilian nylon field.

[0005] The current technical problem to be solved is how to design a reasonable and feasible continuous polymerization device and production process for civilian semi-dull nylon 66 resin that can significantly reduce production costs, increase raw material utilization, and significantly improve production efficiency and product consistency through continuous design and intelligent control system, suitable for large-scale industrial production. Summary of the Invention

[0006] To address the aforementioned issues, this invention proposes a large-capacity continuous polymerization apparatus and production process for semi-dull nylon 66 resin used in civilian filaments. The aim is to achieve efficient and continuous production of semi-dull nylon 66 resin for civilian filaments by optimizing reactor structure design, improving the dispersion mechanism of the matting agent, and implementing intelligent process control. Simultaneously, it ensures the uniformity of the semi-dull properties, providing reliable technical support for the high-end civilian filament sector.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a large-capacity continuous polymerization device for semi-dull nylon 66 resin for civilian use, comprising a salt forming system, a salt storage system, an additive system, an evaporator, a condenser, a reactor, a flash evaporator, a polymerizer, a screw system, a pipeline system, and a control system. The salt forming system and the salt storage system are connected in sequence. The additive system is located between the salt storage system and the evaporator. The condenser, reactor, flash evaporator, polymerizer, and screw system are located after the evaporator in sequence. The control system is used to control the coordinated production of each subsystem.

[0008] The above are the basic embodiments of the present invention, and further improvements, refinements and limitations can be made on the basis of the above: the salt formation system includes a crude salt reactor and a refined salt reactor, wherein the crude salt reactor contains demineralized water, adipic acid and hexamethylenediamine for the preliminary preparation of crude salt, and the refined salt reactor contains demineralized water and hexamethylenediamine for the purification of crude salt.

[0009] The above is the basic embodiment of the present invention, and further improvements, refinements and limitations can be made on the basis of the above: As described, the salt storage system includes a crude salt storage tank and a refined salt storage tank. The crude salt storage tank is located between the crude salt reactor and the refined salt reactor, and the refined salt storage tank is located after the refined salt reactor. The crude salt storage tank and the refined salt storage tank are used to store crude salt and refined salt, respectively.

[0010] The above are the basic embodiments of the present invention, and further improvements, refinements and limitations can be made on the basis of the above: as described, the crude salt reactor is provided with a self-circulating crude salt circulation pipeline, and the crude salt circulation pipeline is provided with a crude salt heat exchanger for heating the salt solution and a crude salt pump for connecting to the crude salt storage tank; the crude salt storage tank is provided with a supply pump connected to the refined salt storage tank.

[0011] The above is the basic embodiment of the present invention, and further improvements, refinements and limitations can be made on the basis of the above: as described, the refined salt storage tank is also equipped with an annular filter, a cooler, a pH meter and a refractometer.

[0012] The above are the basic embodiments of the present invention. Further improvements, refinements and limitations can be made on the basis of the above: such as the control system adjusting the nylon 66 salt solution with different pH values ​​at different temperatures, and adjusting the amount and type of additives and process parameters according to production needs.

[0013] A production process for a large-capacity continuous polymerization apparatus for semi-dull nylon 66 resin for civilian use includes the following steps. Step 1: Under nitrogen sealing conditions of 3 bar, deoxygenated demineralized water, adipic acid, and hexamethylenediamine are mixed and reacted in a crude salt reactor to prepare a crude salt solution, which is then stored in a crude salt storage tank. The concentration of the crude salt solution is 53-63%, the molar ratio of adipic acid to hexamethylenediamine is 1.8-2.4:1, the reaction temperature is 50-70 °C, the temperature of the crude salt storage tank is 55-75 °C, and the pH value of the salt solution is 3.9-5.2. Step 2: The crude salt solution in the crude salt storage tank from Step 1 is supplied to the refined salt reactor via a supply pump. Hexamethylenediamine and demineralized water are added to the nitrogen-sealed refined salt reactor to further adjust the pH value of the salt solution to the required level, and then stored in the refined salt storage tank. The concentration of the refined salt solution is 53-65%, the molar ratio of adipic acid to hexamethylenediamine is 1:0.95-1.1, the reaction temperature is 50-70 ℃, the temperature of the refined salt storage tank is 80-100 ℃, and the pH value of the salt solution is 7.40-7.75. Step 3: The refined salt solution prepared in Step 2 is transported to the evaporator through a pipeline by a supply pump, and the required additives are added through an additive system. The salt solution concentration is completed in the evaporator. After degassing and concentration, the salt solution concentration is 65-78%. At this time, the temperature in the evaporator is 140-158 ℃ and the pressure is 250-300 kPa. The added additives are one or a combination of antioxidant 168, antioxidant 1098, antioxidant 1010, S~EED, antioxidant DNP, and hypophosphite. Step 4: After the concentrated salt in the evaporator is filtered, it is further heated to 185~210 ℃ in the condenser under the action of the pump and further concentrated before entering the bottom of the reactor. In the reactor, it is heated to 225~245 ℃ and begins the polymerization reaction to form a prepolymer. The pressure at this time is 1400~1650 kPa. Step 5: The prepolymer in the reactor is further heated by the flash evaporator supply pump through the heating jacket and transported to the flash evaporator. Moisture is further discharged through negative pressure. The temperature in the flash evaporator reaches 270~280 ℃, and the moisture content is <1%. Step 6: The polymer transfer pump delivers the material to the polymerizer for further heating to 280~288 ℃. Negative pressure is used to increase viscosity to ensure the polymer reaches the required viscosity. The polymer then passes through a heating sleeve. At the polymerizer outlet valve, a certain amount of TiO2 semi-dull masterbatch is injected into the conveying pipeline through the additive system. After being sheared and mixed with the polymer melt by the screw system, the polymer is sent to the pelletizing system through the conveying pipeline. Step 7: The chips from the pelletizing system enter the drying system for further drying and sieving. The chips are then collected and tested for relevant properties in the downstream packaging process.

[0014] The above is the basic implementation of the present invention. Further improvements, refinements and limitations can be made on the basis of the above: for example, the additives added in step three are one or more of antioxidant 168, antioxidant 1098, antioxidant 1010, S-EED, antioxidant DNP, and hypophosphite.

[0015] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention significantly improves production efficiency and product consistency through a continuous process design (salt formation-concentration-polymerization-granulation) and an intelligent control system. Compared with the traditional batch process, the capacity and energy consumption are optimized: the annual capacity of a single continuous polymerization unit can reach 40,000 tons, and the unit energy consumption is reduced by 30%; the nitrogen-sealed crude salt tank + online pH / refractive index monitoring system reduces the fluctuation range of salt concentration to ±0.3% and the pH value stability to ±0.1, ensuring the uniformity of the polymerization reaction from the source.

[0016] (2) While achieving high-efficiency production, this process significantly improves product quality and functional applicability through innovative structural design: TiO2 masterbatch is effectively dispersed in resin through high-shear mixing of screw system, further improving spinnability; this continuous process supports flexible adaptation of antioxidants and matting masterbatch, reduces raw material waste, reduces overall production cost, and significantly enhances market competitiveness. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the apparatus and reaction process of the present invention. Detailed Implementation

[0018] The specific embodiments of the present invention will be further described in detail below with reference to examples.

[0019] A large-capacity continuous polymerization device for semi-dull nylon 66 resin for civilian use includes a salt-forming system, a salt storage system, an additive system, an evaporator, a condenser, a reactor, a flash evaporator, a polymerizer, a screw system, a piping system, and a control system. The salt-forming system and the salt storage system are connected in sequence. The additive system is located between the salt storage system and the evaporator. The condenser, reactor, flash evaporator, polymerizer, and screw system are located after the evaporator in sequence. The control system is used to control the coordinated production of each subsystem.

[0020] The above are the basic embodiments of the present invention, and further improvements, refinements and limitations can be made on the basis of the above: As described, the salt formation system includes a crude salt reactor and a refined salt reactor, wherein the crude salt reactor contains demineralized water, adipic acid and hexamethylenediamine for the preliminary preparation of crude salt, anhydrous hexamethylenediamine is mixed with adipic acid and softened water in the crude salt tank, and the crude salt tank achieves self-circulation through a crude salt pump; the refined salt reactor contains demineralized water and hexamethylenediamine for purifying crude salt.

[0021] The above is the basic embodiment of the present invention, and further improvements, refinements and limitations can be made on the basis of the above: As described, the salt storage system includes a crude salt storage tank and a refined salt storage tank. The crude salt storage tank is located between the crude salt reactor and the refined salt reactor, and the refined salt storage tank is located after the refined salt reactor. The crude salt storage tank and the refined salt storage tank are used to store crude salt and refined salt, respectively.

[0022] The above is a basic embodiment of the present invention, and further improvements, refinements, and limitations can be made based on the above: For example, the crude salt reactor is equipped with a self-circulating crude salt circulation pipeline, which includes a crude salt heat exchanger for heating the salt solution and a crude salt pump for connecting to the crude salt storage tank; the crude salt storage tank is equipped with a supply pump connected to the refined salt storage tank, enabling self-circulation of crude salt to ensure the uniformity of the components in the supply tank; a certain proportion of hexamethylenediamine solution is metered and added to the refined salt tank from the hexamethylenediamine storage tank to control the salt concentration, and the set proportion is adjusted according to the crude salt supply rate. The amount of hexamethylenediamine added is adjusted by the refined salt delivery pump to control the pH value of the salt solution. By adjusting the amount of softened water added to the refined hexamethylenediamine, a certain concentration of hexamethylenediamine solution can be prepared to achieve the final salt concentration.

[0023] The above is the basic embodiment of the present invention, and further improvements, refinements and limitations can be made on the basis of the above: as described, the refined salt storage tank is also equipped with a ring filter, a cooler, a pH meter and a refractometer; the ring filter is used to remove some solid particles that may interfere with the instrument; the cooler is used to control the temperature for more accurate pH measurement; the pH meter is used to control the amount of refined hexamethylenediamine added; the refractometer is used to control the amount of softened water added; the salt solution will flow directly into the nitrogen-sealed salt storage tank, and the storage tank supplies the salt solution to the evaporator for continuous polymerization. Each storage tank has a circulation pipeline for mixing the salt solution to ensure that the salt solution composition is uniform.

[0024] The above describes the basic implementation of this invention, and further improvements, refinements, and limitations can be made based on this: for example, the control system can adjust the pH value of nylon 66 salt solution at different temperatures according to production needs, and regulate the amount and type of additives and process parameters; the required additives can be added before the salt solution is pumped from the salt storage tank to the evaporator. In the evaporator, the salt solution is boiled to evaporate some of the water, thereby concentrating the salt. After filtration, the concentrated salt in the evaporator is pumped and enters the bottom of the reactor through a condenser.

[0025] A production process for a large-capacity continuous polymerization apparatus for semi-dull nylon 66 resin for civilian use includes the following steps. Step 1: Under nitrogen atmosphere, deoxygenated deionized water, adipic acid, and hexamethylenediamine are mixed and reacted in a crude salt reactor to prepare a crude salt solution, which is then stored in a crude salt storage tank. The concentration of the crude salt solution is 53-63%, the molar ratio of adipic acid to hexamethylenediamine is 1.8-2.4:1, the reaction temperature is 50-70 °C, the temperature of the crude salt storage tank is 55-75 °C, and the pH value of the salt solution is 3.9-5.2. Step 2: The crude salt solution in the crude salt storage tank from Step 1 is supplied to the refined salt reactor via a supply pump. Hexamethylenediamine and demineralized water are added to the nitrogen-sealed refined salt reactor to further adjust the pH value of the salt solution to the required level, and then stored in the refined salt storage tank. The concentration of the refined salt solution is 53-65%, the molar ratio of adipic acid to hexamethylenediamine is 1:0.95-1.1, the reaction temperature is 50-70 ℃, the temperature of the refined salt storage tank is 80-100 ℃, and the pH value of the salt solution is 7.40-7.75. Step 3: The refined salt solution prepared in Step 2 is transported to the evaporator through a pipeline by a supply pump, and the required additives are added through an additive system. The salt solution concentration is completed in the evaporator. After degassing and concentration, the salt solution concentration is 65-78%. At this time, the temperature in the evaporator is 140-158 ℃ and the pressure is 250-300 kPa. The added additives are one or a combination of antioxidant 168, antioxidant 1098, antioxidant 1010, S-EED, antioxidant DNP, and hypophosphite. Step 4: After the concentrated salt in the evaporator is filtered, it is further heated to 185~210 ℃ in the condenser under the action of the pump and further concentrated before entering the bottom of the reactor. In the reactor, it is heated to 225~245 ℃ and begins the polymerization reaction to form a prepolymer. The pressure at this time is 1400~1650 kPa. Step 5: The prepolymer in the reactor is further heated and transported to the flash evaporator via a flash pump through a DP:DPO bushing. Moisture is further removed under negative pressure. The temperature in the flash evaporator reaches 270~280 ℃, and the moisture content is <1%. Step 6: The polymer transfer pump delivers the material to the polymerizer for further heating to 280~288 ℃. Negative pressure is used to increase viscosity to ensure the polymer reaches the required viscosity. The polymer then passes through a jacketed pipe heated by DP:DPO. At the polymerizer outlet valve, a certain amount of TiO2 semi-dull masterbatch is injected into the conveying pipeline through the additive system. After being sheared and mixed with the polymer melt by the screw system, the polymer is sent to the pelletizing system through the conveying pipeline. Step 7: The chips from the pelletizing system enter the drying system for further drying and sieving. The chips are then collected and tested for relevant properties in the downstream packaging process.

[0026] The above is the basic implementation of the present invention. Further improvements, refinements and limitations can be made on the basis of the above: for example, the additives added in step three are one or more of antioxidant 168, antioxidant 1098, antioxidant 1010, S~EED, antioxidant DNP, and hypophosphite.

[0027] After preparation, the product is tested using the following methods: The tensile strength and elongation at break of the specimens were tested according to standard GB / T 1040. Type 5 specimens with a thickness of 2±0.2 mm were used, and the test rate was 50 mm / min.

[0028] Differential scanning calorimetry was performed in accordance with the standard GB / T 19466.

[0029] The relative viscosity test shall be conducted in accordance with the provisions of standard GB / T 12006.1-2009.

[0030] The end-group content test shall be conducted in accordance with the provisions of standard Q / NL012.2023.

[0031] Spinability testing was conducted on civilian silk spinning equipment.

[0032] The pH test conditions for PA66 brine were 10 wt% and 20 ± 0.5 °C.

[0033] The relevant performance parameters of the three groups of semi-dull nylon 66 resins for civilian use and a commercial semi-dull nylon 66 resin for civilian use (Comparative Example 1) prepared by the present invention are recorded in Table 1.

[0034] pH value relative viscosity terminal amino Melting point Tensile strength Fiber breaking strength Full roll rate Color fastness Example 1 7.36 2.53 47 263.3 80.2 4.7 95 Level 4 Example 2 7.48 2.56 49 263.6 81.4 5.2 97 Level 4.5 Example 3 7.59 2.47 50 262.9 81.7 5.3 96 Level 4.5 Comparative Example 1 - 2.55 49 262.5 80.3 5.1 97 Level 4.5 Table 1 is a comparison table of various performance parameters of the product test. The performance parameters tested above show that the semi-dull nylon 66 resin for civilian use produced by the device and production method of this invention is close to the performance parameters of commercial nylon 66.

[0035] During the implementation of this invention, researchers found that the method is also applicable to the production process of other civilian nylon 66 resins (such as fully matte civilian nylon 66 resin, glossy civilian nylon 66 resin, etc.). In subsequent research, this method can be used as a basis to explore production processes and formulations suitable for other nylon materials, which can greatly broaden the application field of this method.

[0036] The preferred embodiments and examples of the present invention have been described in detail above with reference to the table. However, the present invention is not limited to the above embodiments and examples. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the concept of the present invention.

Claims

1. A large-capacity continuous polymerization device for semi-dull nylon 66 resin for civilian use, characterized in that: It includes a salt-forming system, a salt storage system, an additive system, an evaporator, a condenser, a reactor, a flash evaporator, a polymerizer, a screw system, a piping system, and a control system. The salt-forming system and the salt storage system are connected in sequence. The additive system is located between the salt storage system and the evaporator. The condenser, reactor, flash evaporator, polymerizer, and screw system are located after the evaporator in sequence. The control system is used to control the coordinated production of each subsystem.

2. The continuous polymerization apparatus for large-capacity civilian-use semi-dull nylon 66 resin according to claim 1, characterized in that: The salt-forming system includes a crude salt reactor and a refined salt reactor. The crude salt reactor contains demineralized water, adipic acid, and hexamethylenediamine for the initial preparation of crude salt, while the refined salt reactor contains demineralized water and hexamethylenediamine for the purification of crude salt.

3. The continuous polymerization apparatus for large-capacity civilian-use semi-dull nylon 66 resin according to claim 2, characterized in that: The salt storage system includes a crude salt storage tank and a refined salt storage tank. The crude salt storage tank is located between the crude salt reactor and the refined salt reactor, and the refined salt storage tank is located after the refined salt reactor. The crude salt storage tank and the refined salt storage tank are used to store crude salt and refined salt, respectively.

4. The continuous polymerization apparatus for large-capacity civilian-use semi-dull nylon 66 resin according to claim 3, characterized in that: The crude salt reactor is equipped with a self-circulating crude salt circulation pipeline, which includes a crude salt heat exchanger for heating the brine and a crude salt pump for connecting to a crude salt storage tank. The crude salt storage tank is equipped with a supply pump that connects to a refined salt storage tank.

5. The continuous polymerization apparatus for large-capacity civilian-use semi-dull nylon 66 resin according to claim 3, characterized in that: The refined salt storage tank is also equipped with a ring filter, a cooler, a pH meter, and a refractometer.

6. The continuous polymerization apparatus for large-capacity civilian-use semi-dull nylon 66 resin according to claim 1, characterized in that: The control system adjusts the amount and type of additives and process parameters at different temperatures and pH values ​​according to production needs.

7. A production process for a large-capacity continuous polymerization apparatus for semi-dull nylon 66 resin for civilian use, characterized in that: Includes the following steps, Step 1: Under nitrogen sealing conditions of 3 bar, deoxygenated demineralized water, adipic acid, and hexamethylenediamine are mixed and reacted in a crude salt reactor to prepare a crude salt solution, which is then stored in a crude salt storage tank. The concentration of the crude salt solution is 53-63%, the molar ratio of adipic acid to hexamethylenediamine is 1.8-2.4:1, the reaction temperature is 50-70 °C, the temperature of the crude salt storage tank is 55-75 °C, and the pH value of the salt solution is 3.9-5.

2. Step 2: The crude salt solution in the crude salt storage tank from Step 1 is supplied to the refined salt reactor via a supply pump. Hexamethylenediamine and demineralized water are added to the nitrogen-sealed refined salt reactor to further adjust the pH value of the salt solution to the required level, and then stored in the refined salt storage tank. The concentration of the refined salt solution is 53-65%, the molar ratio of adipic acid to hexamethylenediamine is 1:0.95-1.1, the reaction temperature is 50-70 ℃, the temperature of the refined salt storage tank is 80-100 ℃, and the pH value of the salt solution is 7.40-7.

75. Step 3: The refined salt solution prepared in Step 2 is transported to the evaporator through a pipeline by a supply pump, and the required additives are added through an additive system. The salt solution concentration is completed in the evaporator. After degassing and concentration, the salt solution concentration is 65-78%. At this time, the temperature in the evaporator is 140-158 ℃ and the pressure is 250-300 kPa. The added additives are one or a combination of antioxidant 168, antioxidant 1098, antioxidant 1010, S~EED, antioxidant DNP, and hypophosphite. Step 4: After the concentrated salt in the evaporator is filtered, it is further heated to 185~210℃ in the condenser under the action of the pump and further concentrated before entering the bottom of the reactor. In the reactor, it is heated to 225~245℃ and the polymerization reaction begins to form a prepolymer. The pressure at this time is 1400~1650 kPa. Step 5: The prepolymer in the reactor is further heated by the flash evaporator supply pump through the heating jacket and transported to the flash evaporator. Moisture is further discharged through negative pressure. The temperature in the flash evaporator reaches 270~280 ℃, and the moisture content is <1%. Step 6: The polymer transfer pump delivers the material to the polymerizer for further heating to 280~288 ℃. Negative pressure is used to increase viscosity to ensure the polymer reaches the required viscosity. The polymer then passes through a heating sleeve. At the polymerizer outlet valve, a certain amount of TiO2 semi-dull masterbatch is injected into the conveying pipeline through the additive system. After being sheared and mixed with the polymer melt by the screw system, the polymer is sent to the pelletizing system through the conveying pipeline. Step 7: The chips from the pelletizing system enter the drying system for further drying and sieving. The chips are then collected and tested for relevant properties in the downstream packaging process.

8. The production process of a large-capacity civilian-use semi-dull nylon 66 resin continuous polymerization device according to claim 7, characterized in that: The additives added in step three are one or more of antioxidant 168, antioxidant 1098, antioxidant 1010, S~EED, antioxidant DNP, and hypophosphite.

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