A continuous production device of low-chlorine polyamide polyamine epichlorohydrin wet strength agent

Abstract

The utility model relates to the technical field of chemical synthesis, specifically relates to a kind of continuous production device of low-chlorine polyamide polyamine epichlorohydrin wet strength agent, including polyamide polyamine epichlorohydrin synthesis system, polyamide polyamine epichlorohydrin synthesis system is connected with ion resin adsorption purification regeneration system, ion resin adsorption purification regeneration system includes multistage resin adsorption column group, its top is connected with steam pipeline, methanol feed pipeline, wet strength agent finished product pipeline, bottom is connected with wet strength agent crude product pipeline, methanol rinsing liquid pipeline, steam condensate pipeline.The continuous production device uses ion resin adsorption purification regeneration system to adsorb small molecule organic chlorine and other impurities in wet strength agent crude product, avoid the problem that wastewater quantity is large, processing difficulty is brought by heat vacuum dehydration technique purification, methanol rinsing liquid produced by impurity removal can be rectified and reused by subsequent treatment process, with obvious economic and environmental protection benefits.

Description

Technical Field

[0001] This utility model relates to the technical field of chemical synthesis, specifically to a continuous production apparatus for a low-chlorinated polyamide polyamine epichlorohydrin wet strength agent. Background Technology

[0002] In the paper industry, polyamide polyamine epichlorohydrin (PAE) wet strength agent has become a key additive in the production of various packaging papers and household paper products due to its ability to significantly improve the wet strength of paper and its good binding properties with fibers. Its synthesis process first prepares polyamide polyamine (PAA) from adipic acid and polyamines (such as diethylenetriamine), and then generates the target polymer through the cyclization and crosslinking reaction of PAA with epichlorohydrin. However, epichlorohydrin has high reactivity and a complex reaction pathway. While generating the PAE main chain structure, it inevitably produces a variety of difficult-to-separate impurities. On the one hand, epichlorohydrin is prone to hydrolysis and ring-opening side reactions, generating small-molecule hydrolyzable organic chlorines such as 1,3-dichloro-2-propanol (DCP) and 3-chloro-1,2-propanediol (MCPD). These impurities not only have poor chemical stability but also slowly release acidic substances during storage, accelerating the degradation and aging of PAE resin. On the other hand, unreacted epichlorohydrin, adipic acid, and other monomers in the reaction system, as well as the inorganic sodium chloride generated by the reaction, will further aggravate product performance defects. Residual monomers can easily cause resin to stratify and exhibit abnormal viscosity fluctuations during storage. Inorganic sodium chloride will adhere to the inner wall of the equipment during subsequent paper sizing, causing long-term accumulation and corrosion of metal parts, shortening the service life of the equipment. At the same time, it will also release irritating odors during the paper drying process, affecting the production environment and the user experience of the end product.

[0003] Crucially, with increasingly stringent food packaging safety standards and environmental requirements for household paper, the restriction on the organic chlorine content in PAE wet strength agents has shifted from "trace amounts allowed" to "near-zero control." These impurities have become the core technical barrier restricting the application of PAE wet strength agents in food contact packaging paper (such as milk carton lining paper and fast food box paper) and high-end household paper (such as baby wipes and medical wipes).

[0004] Currently, mainstream impurity removal technologies in the industry struggle to overcome this bottleneck. Thermal vacuum dehydration technology attempts to volatilize small-molecule chloropropanol using high temperatures of 100-120℃ and negative pressures of -0.08 to -0.1 MPa, but this process suffers from three major drawbacks: First, the high-temperature environment easily triggers cross-linking and degradation of PAE polymer chains, leading to a 10%-15% decrease in the product's wet strength; second, negative pressure operation requires high-power vacuum pumps and sealing equipment, consuming over 30% of the energy in the entire PAE production process, and can only remove 30%-40% of DCP and MCPD, with even lower removal efficiency for MCPD; third, this technology cannot separate inorganic sodium chloride and residual monomers, requiring subsequent water washing processes, further increasing wastewater treatment costs.

[0005] While membrane dialysis technology can remove salts and some small molecule impurities through concentration gradients, it also has significant limitations: firstly, PAE resin molecules easily adsorb and aggregate on the membrane surface, leading to membrane pore blockage. Typically, it needs to be shut down for cleaning after 4-6 hours of operation, and the throughput is reduced from the initial 50 L / (m²). 2 •h) decreased to 15L / (m 2 The membrane has several drawbacks: firstly, it is difficult to meet the requirements of continuous industrial production; secondly, the membrane has extremely poor selectivity for MCPD (molecular diameter of about 0.8nm), which has a molecular size similar to PAE monomers, with a separation factor of only 1.2-1.5, which cannot effectively retain it, resulting in a fluctuation range of 50-200ppm in the organic chlorine content of the finished product, which is far higher than the ≤10ppm standard required for food packaging paper; and thirdly, the replacement cost of membrane modules is high, with the price of membrane material exceeding 2,000 yuan per square meter, and the cleaning process requires the use of strong acids and alkalis, which can easily cause membrane material aging and further increase production costs.

[0006] Furthermore, existing technologies suffer from common problems such as the difficulty in balancing impurity removal efficiency with product performance, and the incompatibility of intermittent operations with continuous production. For example, while increasing temperature in thermal vacuum dehydration technology can improve impurity removal rates, it also exacerbates resin degradation; similarly, while increasing operating pressure in membrane dialysis technology can increase flux, it increases the risk of membrane fouling. These technological bottlenecks not only result in domestic PAE wet strength agent products being concentrated in the low-to-mid-end market, with the high-end market long dominated by foreign brands, but also hinder the transformation of my country's papermaking industry towards "green and high-end" production. Therefore, developing a new impurity removal technology and supporting equipment suitable for crude PAE wet strength agents has become an urgent need to break through the bottlenecks in high-end PAE wet strength agent production and promote the upgrading of my country's papermaking additives industry. Utility Model Content

[0007] To address the problems of high energy consumption, low impurity removal rate, and high maintenance cost in existing polyamide polyamine epichlorohydrin wet strength agent removal technologies, this invention provides a continuous production device for low-chlorinated polyamide polyamine epichlorohydrin wet strength agent. This device achieves precise targeted adsorption of impurities such as small-molecule organic chlorine, simultaneously removing residual monomers and salts. Furthermore, it meets the requirements for continuous operation of more than 72 hours in industrial production while ensuring no damage to PAE performance and no secondary pollution.

[0008] The specific technical solution is as follows: A continuous production apparatus for a low-chlorinated polyamide polyamine epichlorohydrin wet-strength agent includes a polyamide polyamine epichlorohydrin synthesis system. The polyamide polyamine epichlorohydrin synthesis system is connected to an ion exchange resin adsorption purification and regeneration system. The ion exchange resin adsorption purification and regeneration system includes a multi-stage resin adsorption column assembly. The top of the multi-stage resin adsorption column assembly is connected to a steam pipe, a methanol feed pipe, and a wet-strength agent finished product pipe. The bottom of the multi-stage resin adsorption column assembly is connected to a wet-strength agent crude product pipe, a methanol eluent pipe, and a steam condensate pipe. Valves are installed on the steam pipe, methanol feed pipe, wet-strength agent finished product pipe, wet-strength agent crude product pipe, methanol eluent pipe, and steam condensate pipe. The ion exchange resin adsorption purification and regeneration system is connected to the polyamide polyamine epichlorohydrin synthesis system via the wet-strength agent crude product pipe.

[0009] The aforementioned continuous production unit utilizes an ion exchange resin adsorption purification and regeneration system to adsorb and purify impurities in the crude wet-strength agent. This system can precisely remove specific impurities, particularly small-molecule organic chlorine compounds, and is characterized by simple operation and low energy consumption. Simultaneously, through a combination of dedicated pipelines and valves, four main functions—crude product feeding, finished product discharging, methanol regeneration, and steam desorption—can be independently controlled, preventing cross-contamination between different media. Precise valve control can adjust material flow rate and steam / methanol usage to adapt to different purification requirements, improving impurity removal rate and regeneration efficiency.

[0010] Furthermore, the ion exchange resin adsorption purification and regeneration system is connected to the wet strength agent finished product storage system via a finished product pipeline. This device enables integrated continuous production from raw material synthesis, crude product purification, and finished product storage, reducing intermediate material transfer links and lowering material loss and external contamination risks. At the same time, each system has a clear division of labor, facilitating individual parameter control (such as synthesis temperature and adsorption flow rate), thereby improving overall production efficiency and product stability.

[0011] Furthermore, the multi-stage resin adsorption column assembly includes at least a first-stage resin adsorption column, a second-stage resin adsorption column, and a final-stage resin adsorption column. Each stage of the resin adsorption column is connected sequentially via a communicating vessel. The top of the final-stage resin adsorption column is connected to the bottom of the first-stage resin adsorption column via a loop pipe. Multi-stage series adsorption can improve the impurity removal rate by progressively trapping impurities, solving the problem of incomplete adsorption in single columns. The loop pipe creates a "final-to-first-stage" circulation path, and the stable material flow from the communicating vessel allows the regenerated resin column to be quickly integrated into production, achieving continuous adsorption and reducing downtime and maintenance costs.

[0012] Furthermore, the polyamide polyamine epichlorohydrin synthesis system includes a first reactor, a second reactor, and a crude wet-strength agent storage tank. The inlet of the first reactor is connected to the adipic acid storage tank, the diethylenetriamine storage tank, and the soft water storage tank; the inlet of the second reactor is connected to the epichlorohydrin storage tank and the dilute sulfuric acid storage tank; the inlet of the second reactor is connected to the outlet of the first reactor; and the second reactor is connected to the crude wet-strength agent storage tank via a material pipeline. The first and second reactors have clearly defined functions, respectively synthesizing polyamide polyamine (PAA) prepolymer and crude wet-strength agent. Stepwise temperature control and precise feed of raw materials ensure sufficient synthesis reaction and reduce by-product generation. Simultaneously, the crude wet-strength agent storage tank buffers the crude product, preventing production interruptions caused by mismatches between synthesis and purification schedules.

[0013] Furthermore, the methanol eluent pipeline and the steam condensate pipeline are shared pipelines, with the flow direction controlled by valves. This reduces the number of pipelines laid, lowering equipment installation costs and space occupation; precise valve flow control prevents the simultaneous flow of the two media, ensuring the independent functions of methanol eluent recovery (desorption of impurities) and steam condensate recovery (energy saving), while also simplifying pipeline maintenance procedures.

[0014] Furthermore, the valve is an electric valve, which can realize remote automated control, replace manual operation, and reduce labor costs; at the same time, it reduces the delay of manual operation, improves the accuracy of valve opening and closing and flow regulation, avoids material waste or process parameter deviation caused by human operation error, and ensures production stability.

[0015] Furthermore, both the first and second reaction vessels are equipped with jackets. By introducing heating or cooling media (such as steam or cold water) through the jackets, the temperature inside the reaction vessels can be precisely controlled to meet the requirements of the wet strength agent production process. The jackets provide uniform temperature control, which can prevent the decomposition of raw materials or the generation of by-products caused by excessively high local temperatures, thereby improving the purity of the crude product.

[0016] Furthermore, the wet strength agent finished product storage system includes a wet strength agent finished product storage tank, which is connected to a multi-stage resin adsorption column assembly via a wet strength agent finished product pipeline. The finished product pipeline directly connects to the multi-stage resin adsorption column assembly and the finished product storage tank, helping to reduce external contamination during finished product transfer. The finished product storage tank serves as a buffer for the wet strength agent, preventing production stoppages due to delayed subsequent filling or transportation, while also facilitating unified management of the quantity and quality of the finished product.

[0017] The beneficial effects of this utility model are as follows: 1. This continuous production unit uses an ion exchange resin adsorption purification and regeneration system to remove small-molecule organic chlorine and other impurities from the crude polyamide polyamine epichlorohydrin wet strength agent. This avoids the problems of large wastewater volume and difficult treatment caused by thermal vacuum dehydration technology. The methanol wash liquid generated during the impurity removal process can be recycled by distillation through subsequent treatment processes. The remaining distillation product is separated by extraction, turning the original pollutants into by-products, which has significant economic and environmental benefits.

[0018] 2. Using the above-mentioned continuous production equipment to purify crude PAE wet strength agent is a simple process with high purification accuracy, significantly improved product quality, and low equipment maintenance costs. All valves in the equipment are electrically interlocked and controlled, and the entire system is continuously and automatically operated using PLC programming. This simplifies operation, reduces manual labor intensity, and minimizes product contamination caused by operational errors. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the continuous production apparatus for low-chlorinated polyamide polyamine epichlorohydrin wet strength agent in Embodiment 1 of this utility model.

[0021] In the diagram: 1. Adipic acid storage tank; 2. Diethylenetriamine storage tank; 3. Soft water storage tank; 4. First reaction vessel; 5. Second reaction vessel; 6. Epichlorohydrin storage tank; 7. Dilute sulfuric acid storage tank; 8. Crude wet strength agent storage tank; 9. Crude wet strength agent pipeline; 10. Steam pipeline; 11. Methanol feed pipeline; 12. Finished wet strength agent pipeline; 13. Loop pipeline; 14. Multi-stage resin adsorption column assembly; 15. Methanol eluent pipeline; 16. Finished wet strength agent storage tank; 17. Steam condensate pipeline. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0023] Example 1 A continuous production apparatus for a low-chlorinated polyamide polyamine epichlorohydrin wet strength agent includes a polyamide polyamine epichlorohydrin synthesis system, an ion exchange resin adsorption purification and regeneration system, and a wet strength agent finished product storage system connected in sequence.

[0024] The polyamide polyamine epichlorohydrin synthesis system includes a first reactor 4, a second reactor 5, and a crude wet-strength agent storage tank 8. The inlet of the first reactor 4 is connected to an adipic acid storage tank 1, a diethylenetriamine storage tank 2, and a soft water storage tank 3. The inlet of the second reactor 5 is connected to an epichlorohydrin storage tank 6 and a dilute sulfuric acid storage tank 7. The inlet of the second reactor 5 is connected to the outlet of the first reactor 4. The second reactor 5 and the crude wet-strength agent storage tank 8 are connected via a material pipeline. Both the first reactor 4 and the second reactor 5 are equipped with jackets.

[0025] The ion exchange resin adsorption purification and regeneration system includes a multi-stage resin adsorption column group 14, which comprises a first-stage resin adsorption column, a second-stage resin adsorption column, and a final-stage resin adsorption column. These columns are sequentially connected via a communicating vessel. The top of the final-stage resin adsorption column is connected to the bottom of the first-stage resin adsorption column via a loop pipe 13. Each resin adsorption column in the multi-stage resin adsorption column group 14 has three sets of pipes connected to its top: a steam pipe 10, a methanol feed pipe 11, and a wet-strength agent finished product pipe 12. Each resin adsorption column also has three sets of pipes connected to its bottom: a wet-strength agent crude product pipe 9, a methanol eluent pipe 15, and a steam condensate pipe 17. Valves are installed on all three pipes, all controlled by electric valve interlocks. The entire system operates continuously and automatically using PLC programming. Among them, the methanol wash liquid pipeline 15 and the steam condensate pipeline 17 are shared pipelines, and the flow direction is controlled by valves.

[0026] The wet strength agent finished product storage system includes a wet strength agent finished product storage tank 16, and the wet strength agent finished product storage tank 16 and the multi-stage resin adsorption column group 14 are connected through a wet strength agent finished product pipeline 12.

[0027] Example 2 The low-chlorinated polyamide polyamine epichlorohydrin wet strength agent was produced using the continuous production equipment described in Example 1. The specific steps are as follows: (1) Add a certain mass of adipic acid and ethylenetriamine to the first reaction vessel 4, heat to 160°C, react for 3 hours, cool to 80°C, add a certain amount of soft water to the first reaction vessel 4 to dilute, and obtain a polyamide polyamine (PAA) solution. (2) After the temperature of the PAA solution drops to 50°C, the PAA solution is added to the second reaction vessel 5, and epichlorohydrin is slowly added dropwise. During the dropwise addition, the temperature is controlled not to exceed 70°C. The temperature is kept for 2 hours, and dilute sulfuric acid is added to adjust the pH to terminate the reaction. The crude wet strength agent is obtained and placed in the crude wet strength agent storage tank 8. (3) The crude wet strength agent first enters from the feed valve at the bottom of the first-stage resin adsorption column and enters the multi-stage resin adsorption column group 14 in series. The qualified product is discharged from the top of the last-stage resin adsorption column and flows into the wet strength agent finished product storage tank 16 through the wet strength agent finished product pipeline 12. When the discharge amount reaches a certain adsorption multiple, one adsorption process is completed. (4) After adsorption is complete, the first-stage resin adsorption column is saturated. Open the valve of the methanol feed pipe 11, let it enter from the top of the first-stage resin adsorption column, and then flow out from the bottom of the first-stage resin adsorption column and into the methanol eluent pipe 15 for discharge. (5) Open the valve of the steam pipe 10. Steam enters from the top of the first-stage resin adsorption column. When the amount of steam reaches a certain amount, all the methanol adsorbed by the resin adsorption column is blown out. After cooling, it flows out through the steam condensate pipe 17. (6) After the resin adsorption column is cooled down, adjust the valve of the wet strength agent crude product pipeline 9. The crude product enters from the bottom of the second-stage resin adsorption column, passes through the series closed loop of the multi-stage resin adsorption column group 14, and exits from the top of the first-stage resin adsorption column after regeneration and cooling, thus carrying out the second cycle of adsorption separation.

[0028] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the present invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be included within the protection scope of the present invention.

Claims

1. A continuous production apparatus for a low-chlorinated polyamide polyamine epichlorohydrin wet strength agent, comprising a polyamide polyamine epichlorohydrin synthesis system, characterized in that, The polyamide polyamine epichlorohydrin synthesis system is connected to an ion exchange resin adsorption purification and regeneration system. The ion exchange resin adsorption purification and regeneration system includes a multi-stage resin adsorption column assembly. The top of the multi-stage resin adsorption column assembly is connected to a steam pipe, a methanol feed pipe, and a wet strength agent finished product pipe. The bottom of the multi-stage resin adsorption column assembly is connected to a wet strength agent crude product pipe, a methanol eluent pipe, and a steam condensate pipe. Valves are installed on the steam pipe, methanol feed pipe, wet strength agent finished product pipe, wet strength agent crude product pipe, methanol eluent pipe, and steam condensate pipe. The ion exchange resin adsorption purification and regeneration system is connected to the polyamide polyamine epichlorohydrin synthesis system through the wet strength agent crude product pipe.

2. The continuous production apparatus for a low-chlorinated polyamide polyamine epichlorohydrin wet strength agent as described in claim 1, characterized in that, The ion exchange resin adsorption purification and regeneration system is connected to the wet strength agent finished product storage system via a finished product pipeline.

3. The continuous production apparatus for a low-chlorinated polyamide polyamine epichlorohydrin wet strength agent as described in claim 1, characterized in that, The multi-stage resin adsorption column assembly includes at least a first-stage resin adsorption column, a second-stage resin adsorption column, and a final-stage resin adsorption column. Each stage of the resin adsorption column is connected to the next stage via a communicating vessel. The top of the final-stage resin adsorption column is connected to the bottom of the first-stage resin adsorption column via a loop pipe.

4. The continuous production apparatus for a low-chlorinated polyamide polyamine epichlorohydrin wet strength agent as described in claim 1, characterized in that, The polyamide polyamine epichlorohydrin synthesis system includes a first reactor, a second reactor, and a crude wet strength agent storage tank. The inlet of the first reactor is connected to an adipic acid storage tank, a diethylenetriamine storage tank, and a soft water storage tank. The inlet of the second reactor is connected to an epichlorohydrin storage tank and a dilute sulfuric acid storage tank. The inlet of the second reactor is connected to the outlet of the first reactor. The second reactor and the crude wet strength agent storage tank are connected via a material pipeline.

5. The continuous production apparatus for a low-chlorinated polyamide polyamine epichlorohydrin wet strength agent as described in claim 1, characterized in that, The methanol wash liquid pipeline and the steam condensate pipeline are shared pipelines, and the flow direction is controlled by valves.

6. A continuous production apparatus for a low-chlorinated polyamide polyamine epichlorohydrin wet strength agent as described in claim 1 or 5, characterized in that, The valve is an electric valve.

7. The continuous production apparatus for a low-chlorinated polyamide polyamine epichlorohydrin wet strength agent as described in claim 4, characterized in that, Both the first and second reactors are equipped with jackets.

8. The continuous production apparatus for a low-chlorinated polyamide polyamine epichlorohydrin wet strength agent as described in claim 2, characterized in that, The wet strength agent finished product storage system includes a wet strength agent finished product storage tank, and the wet strength agent finished product storage tank and a multi-stage resin adsorption column group are connected by a wet strength agent finished product pipeline.

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