A process and apparatus for producing epoxy resin that improves the recycling rate of stripping water.

Abstract

This invention belongs to the field of epoxy resin technology, specifically relating to an epoxy resin production process and apparatus for improving the recycling rate of stripping water. The epoxy resin production process for improving the recycling rate of stripping water includes the following steps: Epoxy resin reaction: collecting the aqueous phase from vacuum distillation and the bubbling azeotropic aqueous phase in a stripping tower, and then feeding them into a stripping water treatment vessel. Alkali dechlorination, toluene extraction, and epoxy resin purification: the resin liquid from the reaction vessel in step a is fed into a purification vessel, and the toluene phase obtained in step d is added. After completion, the reaction liquid is subjected to stepwise settling and separation to obtain toluene resin, and benzene removal to obtain the finished epoxy resin. The epoxy resin production process and apparatus for improving the recycling rate of stripping water provided by this invention are simple and easy to implement, require no significant addition of equipment, have low processing costs, and can effectively remove organic chlorine from stripping water, allowing it to be directly reused in production.

Description

Technical Field

[0001] This invention belongs to the field of epoxy resin technology, specifically relating to an epoxy resin production process and equipment for improving the recycling rate of stripping water. Background Technology

[0002] Epoxy resins, especially bisphenol A type epoxy resins, are typically produced through a process of polycondensation of epichlorohydrin and bisphenol A under alkaline conditions. This typical process includes stages such as dissolution, reaction, purification (washing, extraction), and benzene removal. Depending on the reaction conditions, the synthesis methods for bisphenol A type epoxy resins are mainly divided into one-step and two-step methods. The one-step method involves directly performing ring-opening and ring-closing polycondensation reactions of bisphenol A and epichlorohydrin under the action of sodium hydroxide. This process is relatively mature, but the reaction time is long and the consumption of epichlorohydrin is high. The two-step method first involves an etherification reaction between bisphenol A and epichlorohydrin to generate chlorohydrin ethers, followed by a single addition of alkaline solution for ring-closing reaction. This method has a shorter reaction time, more stable operation, and produces less waste, making it the preferred mainstream process route.

[0003] During the reaction stage, to promote the forward reaction and recover excess epichlorohydrin, the system often employs vacuum distillation. The distilled mixture is condensed and allowed to settle and separate into layers. The epichlorohydrin-enriched lower layer can be directly returned to the system as a production feedstock, while the upper aqueous phase (i.e., stripper water) enters the stripping section for further treatment. The stripper water has the following significant characteristics: firstly, it has an extremely high chemical oxygen demand (COD) (up to 50,000 mg / L), containing a large amount of incompletely separated organic matter; secondly, it contains dissolved organochlorine byproducts generated from the hydrolysis of epichlorohydrin. Actual testing shows that the total chlorine content of the stripper water is typically 1000–2000 ppm, and the vast majority of it is organochlorine, mainly including chloropropanediol and other chlorinated alcohols. In the stripping tower, steam is introduced to further remove residual recyclable epichlorohydrin from the water. However, even after treatment, its chemical oxygen demand can still reach about 20,000 mg / L, and the stripping operation has extremely limited ability to remove dissolved organochlorine byproducts.

[0004] To reduce production costs and achieve water resource recycling, some manufacturers have attempted to directly reuse stripping water in the refining process to extract salts from the reaction system. However, because stripping water carries a large amount of organochlorine compounds such as monochloropropanediol, these compounds enter the resin phase during reuse, leading to a significant increase in the total chlorine content of the final epoxy resin. This severely affects the quality of the epoxy resin, particularly key indicators such as its electrical insulation properties. Simultaneously, the amount of epoxy resin wastewater discharged is approximately 2 to 2.5 times the amount of product. If the high concentrations of sodium chloride and organic solvents contained in this wastewater are not effectively recovered and utilized, it not only causes serious resource waste but also poses significant challenges to downstream biochemical treatment. Epoxy resin production wastewater mainly includes epichlorohydrin, bisphenol A, toluene, aged resin, monochloropropanediol, and other organic matter, while also containing a small amount of sodium hydroxide. The wastewater has a COD as high as 30,000 mg / kg, a TOC of 10,000 mg / kg, and a solid content (including salts and organic matter) of approximately 30.0 wt%.

[0005] For the treatment of epoxy resin wastewater containing organochlorine or high concentrations of organic matter, various treatment methods have been developed in the prior art. For example, Chinese patent CN109231637A discloses a method for the resource utilization of epoxy resin wastewater. After pretreatment in a stripping tower, the bottom water of the tower undergoes primary evaporation and concentration, pH adjustment to neutral, and secondary evaporation and concentration. The concentrate is then chlorinated and distilled under reduced pressure to obtain high-purity dichloropropanol. Although this method achieves the resource conversion of glycerol and monochloropropanol in the wastewater into dichloropropanol, the process is complex, involving multiple concentration and chlorination steps. The COD of the distillation condensate produced in the process is still as high as 1200 mg / L, and the water quality is difficult to meet the requirements for direct reuse in the epoxy resin refining process, which has strict purity requirements. In addition, the method disclosed in CN110746270A, which recovers monochloropropanediol from wastewater through processes such as stripping, reaction extraction, distillation and hydrolysis distillation, also has problems such as long process flow, large equipment investment and high operating costs. Moreover, the treated effluent still needs further biochemical treatment, making it difficult to achieve direct and safe reuse. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide an epoxy resin production process and production device that improves the recycling rate of stripping water. It is simple and easy to implement, does not require a large amount of new equipment, has low processing cost, and can effectively remove organic chlorine from stripping water so that it can be directly reused in production.

[0007] The epoxy resin production process for improving the recycling rate of stripping water according to the present invention includes the following steps: a. Reaction: Bisphenol A and epichlorohydrin are added to a reaction vessel, and then a benzyltriethylammonium chloride epichlorohydrin solution is added to react. An alkaline solution is added, and the mixture is distilled under reduced pressure to separate water and epichlorohydrin. The epichlorohydrin is returned to the reaction vessel, and the aqueous phase finally enters the stripping tower. Bubbling is performed after the reaction is completed. b. Collect stripping water: Collect the aqueous phase from the vacuum distillation in step a and the bubbling azeotropic aqueous phase in the stripping tower, and then pump it into the stripping water treatment vessel. c. Alkaline dechlorination: Add an alkaline solution to the stripping water treatment vessel, adjust the pH to 8-13, add a selective accelerator, heat to 60-110℃, and maintain the temperature for reaction; d. Toluene extraction: Add toluene to the stripped water after the reaction, stir thoroughly, let stand and separate into layers to obtain a purified aqueous phase and a toluene phase. Separate the purified aqueous phase to a reclaimed water tank. e. Refining: The resin liquid in the reaction vessel of step a is pumped into the refining vessel, and the toluene phase obtained in step d (the mass ratio of bisphenol A to toluene phase is 1:1.9) is added to the refining vessel. The temperature is raised to 70~90℃ for reaction. After the reaction is completed, the reaction solution is separated by stepwise static separation to obtain toluene resin. Benzene is removed to obtain the epoxy resin product.

[0008] In step a, the initial temperature is 40-45℃, the mass ratio of bisphenol A to epichlorohydrin is 1:2.0-3.0, and the mixture is kept at this temperature for 30-45 minutes under anaerobic conditions. Then, the temperature is raised to 50-60℃, and a benzyltriethylammonium chloride solution in epichlorohydrin is added. The reaction is allowed to proceed for 2-3 hours. The benzyltriethylammonium chloride solution in epichlorohydrin is a solution obtained by dissolving benzyltriethylammonium chloride in epichlorohydrin. Furthermore, in this step, the mass ratio of bisphenol A, epichlorohydrin (referring only to epichlorohydrin that dissolves benzyltriethylammonium chloride), and benzyltriethylammonium chloride is 1:0.03-0.05:0.01-0.02.

[0009] In step a, the alkaline solution is added dropwise under controlled conditions of 20-23 kPa and 60-65°C. The mass fraction of the alkaline solution is 40-50%, and the dropwise addition time is 3-5 hours.

[0010] The bubbling conditions in step a are: pressure 1~5 kPa, temperature 120~130℃, and steam bubbling for 30~60 min.

[0011] The stripping water from the stripping water treatment vessel in step b has a total chlorine content of 1000~2000ppm and a pH of 7~9.

[0012] In step c, the accelerator is one of tert-butanol, isopropanol, or ethylene glycol monomethyl ether, and the mass of the accelerator added is 0.5-1% of the mass of the stripping water.

[0013] In step d, the volume of toluene added is 0.2 to 1 times the volume of stripping water, and the mixture is stirred thoroughly for 10 to 60 minutes.

[0014] The specific steps for the step-by-step separation and settling in step e are as follows: Step 1: Add benzyltriethylammonium chloride and a 10-15% (w / w) alkaline solution to the reaction solution, and allow the mixture to stand and separate after the reaction. Step 2: Stir with recycled water for 10-30 minutes, let stand and separate the liquid to remove salt and impurities, and send the lower aqueous phase to the wastewater tank. Step 3: Add 1-2% (w / w) of disodium hydrogen phosphate aqueous solution, stir for 10-30 minutes, let stand and separate the liquids, and send the lower aqueous phase to the water tank for recycling. Step 4: Add pure water, stir for 10-30 minutes, let stand and separate the liquids, and send the lower aqueous phase to the recycling tank; Step 5: Heat to 110~120℃, remove water, filter, and obtain toluene resin.

[0015] In step e, benzene removal involves feeding toluene resin into a benzene removal reactor, reducing the pressure to 1-5 kPa, heating to 130-150°C, recovering toluene, and then bubbling with steam for 30-60 minutes to obtain the epoxy resin product.

[0016] The epoxy resin production process for improving the recycling rate of stripping water uses a production apparatus including a reactor and a stripping tower. The gas phase pipeline at the top of the stripping tower is connected to a second water separator, which is connected to a stripped water tank. The stripped water tank is connected to a stripping water treatment reactor. The bottom discharge pipeline of the stripping water treatment reactor is connected to a recycled water tank, which is connected to a refining reactor. The middle discharge pipeline of the stripping water treatment reactor is connected to a toluene resin clear liquid tank. An alkaline solution pipeline and a toluene pipeline are installed on the stripping water treatment reactor.

[0017] Preferably, the reactor is equipped with a feed pipe.

[0018] Preferably, the reactor is connected to a water separator via a pipeline, the water separator is connected to a reaction tank via a water pump, and the reaction tank is connected to a stripping tower via a water pump.

[0019] Preferably, the top of the stripping tower is connected to the second water distributor via a pipeline, the second water distributor is connected to the stripped water tank via a pipeline, and the stripped water tank is connected to the stripped water treatment vessel via a stripping water pump.

[0020] Preferably, the reaction liquid in the reactor is connected to the purification reactor via a pipeline.

[0021] Preferably, the stripping water treatment vessel is equipped with an alkaline solution pipeline and a toluene pipeline.

[0022] Preferably, the bottom pipeline of the stripping water treatment vessel is connected to the recycled water tank, and the recycled water tank is connected to the refining vessel through a recycled water pump.

[0023] Preferably, the middle part of the stripping water treatment vessel is connected to the toluene resin clearing tank via a pipeline, and the toluene resin clearing tank is connected to the refining vessel via a clearing pump.

[0024] Preferably, the bottom of the refining vessel is equipped with two pipelines, one connected to the wastewater tank and the other connected to the recycled water tank.

[0025] Preferably, the lower part of the refining vessel is connected to a filter via a pipeline, and the filter is connected to the benzene removal vessel via a pipeline.

[0026] Specifically, the epoxy resin production process for improving the recycling rate of stripping water according to the present invention includes the following steps: a. Reaction: In a reaction vessel, at an initial temperature of 40-45℃, add bisphenol A and epichlorohydrin, making the mass ratio of bisphenol A to epichlorohydrin 1:2.0-3.0. Maintain the temperature and stir for 30-45 minutes under anaerobic conditions. Continue heating the reaction vessel to 50-60℃, then add a benzyltriethylammonium chloride solution in epichlorohydrin and stir until homogeneous. React for 2-3 hours. Under conditions of 20-23 kPa and 60-65℃, add a 40-50% alkaline solution dropwise to the reaction vessel over 3-5 hours under negative pressure (2...). The distillation reaction is carried out at 0~23kPa. During the reaction, epichlorohydrin and water are recovered to the water separator. Epichlorohydrin is returned to the reactor, and the aqueous phase is pumped to the reaction water tank and then into the stripping tower. After the main reaction is completed, the reactor is heated to 120~130℃ and the reactor pressure reaches 1~5kPa. Steam is bubbled for 30~60min. Using the azeotropic principle, the epichlorohydrin and water generated by steam bubbling in the system are recovered to the water separator. The water in the upper layer of the water separator is pumped into the reaction water tank. According to the production schedule, the reaction water in the reaction water tank is pumped into the stripping tower for stripping.

[0027] b. Collection of stripping water: Collect the aqueous phase from the vacuum distillation in step a and the bubbling azeotropic aqueous phase in the stripping tower. The aqueous phase after stripping is the stripping water, which contains organochlorine compounds such as 1-chloro-2,3-propanediol, with a total chlorine content of 1000~2000ppm and a pH of 7~9. This stripping water is sent out for the next step of alkaline dechlorination treatment.

[0028] c. Alkaline dechlorination: Add an alkaline solution to the stripping tower, adjust the pH to 8-13, add a selective promoter, heat to 60-110℃, and maintain the temperature for 0.5-3 hours.

[0029] In this reaction: CH2Cl-CH(OH)-CH2OH+OH - →CH2(O)CH-CH2OH+Cl- +H2O, organic chlorine is converted into inorganic chloride ions, and glycidol is generated at the same time.

[0030] d. Toluene extraction: Add toluene to the stripped water after step c. The volume of toluene added is 0.2 to 1 times the volume of the stripped water. Stir thoroughly for 10 to 60 minutes to transfer glycidol from the aqueous phase to the toluene phase. Allow to stand and separate into layers to obtain a purified aqueous phase and a toluene phase. The total chlorine in the purified aqueous phase is significantly reduced (inorganic chloride ion content ≤ 500 ppm, organic chlorine not detected). The toluene phase contains toluene and the extracted glycidol. The purified aqueous phase is separated and sent to a reclaimed water tank for reuse.

[0031] e. Refining: The resin liquid in the reaction vessel of step a is pumped into the refining vessel, and the toluene phase obtained in step d (mass ratio of bisphenol A to toluene phase 1:1.9) is added to the refining vessel. The temperature is raised to 70~90℃ for reaction. After the reaction is completed, the reaction liquid is separated by stepwise settling. The toluene resin is filtered and pumped into the benzene removal vessel. The pressure is reduced to 1~5kPa, the temperature is raised to 130~150℃, the toluene is recovered, and then steam is bubbled for 30~60min to obtain the epoxy resin product. The stepwise settling and separation method is as follows: Step 1: Add benzyltriethylammonium chloride (catalyst) and a 10-15% (w / w) alkaline solution, stir for 2-3 hours, and let stand to separate the liquids; Step 2: Stir with recycled water for 10-30 minutes, let stand and separate the liquids; remove salts and impurities, and send the lower aqueous phase to the wastewater tank; Step 3: Add 1-2% (w / w) of disodium hydrogen phosphate aqueous solution, stir for 10-30 minutes, let stand and separate the liquids, and send the lower aqueous phase to the water tank for recycling. Step 4: Add pure water, stir for 10-30 minutes, let stand and separate the liquids, and send the lower aqueous phase to the recycling tank; Step 5: Heat to 110~120℃, perform dehydration, filter, and obtain toluene resin.

[0032] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention solves the technical problem of removing organic chlorine (such as monochloropropanediol) from stripping water by using a two-step synergistic treatment of alkaline dechlorination and toluene extraction. Organic chlorine was not detected in the purified water phase after treatment, and the total chlorine content was significantly reduced to below 500 ppm. The water quality is high and can be directly reused in the epoxy resin refining process, which has extremely strict requirements for ion content. This truly realizes the high-value recycling of stripping water within the closed-loop process and avoids the adverse effects on key indicators such as the electrical performance of the product caused by substandard water quality in traditional methods.

[0033] (2) The process of this invention is simple and easy to implement, requiring no significant addition of complex equipment, and has low processing costs. Compared with the complex process of existing technologies that require multiple steps such as multi-stage evaporation and concentration, chlorination reaction, and distillation, this invention only requires adding alkali and accelerator to the stripped water treatment vessel for heating and reaction, followed by extraction with toluene to complete the purification. At the same time, the toluene phase rich in glycidol after extraction can be directly reused as the extractant in the refining section without additional separation and regeneration, significantly reducing equipment investment and operating energy consumption, and achieving high operating efficiency.

[0034] (3) This invention achieves efficient recycling and utilization of resources throughout the entire process. On the one hand, the organic chlorine pollutants in the stripping water are converted into glycidol and extracted and recovered by toluene, ultimately participating in the refining reaction, turning waste into treasure; on the other hand, the purified water phase completely replaces the fresh water and is reused in the washing step of the refining section, significantly reducing the amount of high-concentration organic wastewater generated and the amount of fresh water consumed. The entire process is green and environmentally friendly, conforms to the concept of circular economy, and significantly reduces the load and cost of subsequent wastewater treatment. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the apparatus used in the treatment process of epoxy resin production stripping water according to the present invention.

[0036] In the diagram: 1. Water separator one; 2. Water pump one; 3. Reaction water tank; 4. Water pump two; 5. Stripping tower; 6. Water separator two; 7. Stripped water tank; 8. Stripped water pump; 9. Stripped water treatment vessel; 10. Reclaimed water tank; 11. Reclaimed water pump; 12. Toluene resin clear liquid tank; 13. Clear liquid pump; 14. Refining vessel; 15. Filter; 16. Benzene removal vessel; 17. Alkaline solution pipeline; 18. Toluene pipeline; 19. Feed pipeline; 20. Reaction vessel; 21. Wastewater tank. Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments.

[0038] The epoxy resin production process for improving the recycling rate of stripping water of the present invention employs a production apparatus including a reaction vessel 20 and a stripping tower 5. The gas phase pipeline at the top of the stripping tower 5 is connected to a water separator 6, the water separator 6 is connected to a stripped water tank 7, the stripped water tank 7 is connected to a stripping water treatment vessel 9, the bottom discharge pipeline of the stripping water treatment vessel 9 is connected to a recycled water tank 10, the recycled water tank 10 is connected to a refining vessel 14, the middle discharge pipeline of the stripping water treatment vessel 9 is connected to a toluene resin clear liquid tank 12, and an alkaline solution pipeline 17 and a toluene pipeline 18 are provided on the stripping water treatment vessel 9.

[0039] The reactor 20 is equipped with a feed pipe 19.

[0040] The reactor 20 is connected to the water separator 1 via a pipeline. The water separator 1 is connected to the reaction water tank 3 via the water pump 2. The reaction water tank 3 is connected to the stripping tower 5 via the water pump 4.

[0041] The top of the stripping tower 5 is connected to the second water distributor 6 via a pipeline. The second water distributor 6 is connected to the stripped water tank 7 via a pipeline. The stripped water tank 7 is connected to the stripped water treatment vessel 9 via the stripped water pump 8.

[0042] The reaction liquid in the reactor 20 is connected to the purification reactor 14 through a pipeline.

[0043] The stripping water treatment vessel 9 is equipped with an alkaline solution pipeline 17 and a toluene pipeline 18.

[0044] The bottom pipeline of the stripping water treatment vessel 9 is connected to the recycled water tank 10, and the recycled water tank 10 is connected to the refining vessel 14 through the recycled water pump 11.

[0045] The middle part of the stripping water treatment vessel 9 is connected to the toluene resin clear liquid tank 12 via a pipeline, and the toluene resin clear liquid tank 12 is connected to the refining vessel 14 via the clear liquid pump 13.

[0046] The bottom of the refining vessel 14 is equipped with two pipelines, one of which is connected to the wastewater tank 21 and the other is connected to the recycled water tank 10.

[0047] The lower part of the refining vessel 14 is connected to the filter 15 via a pipeline, and the filter 15 is connected to the benzene removal vessel 16 via a pipeline.

[0048] Water separator 1: Stores and separates reaction water; Pump 2: Primarily transports reaction water to the reaction water tank; Reaction water tank 3: Primarily stores reaction water; Pump 4: Primarily transports stripping water to the stripping tower; Stripping tower 5: Primarily transports a mixture containing epichlorohydrin and water through the liquid phase outlet to water separator 2; Water separator 6: Primarily separates epichlorohydrin and stripping water; Post-stripping water tank 7: Primarily stores stripping water; Stripping water pump 8: Primarily pumps stripping water to the stripping water treatment vessel according to production schedule; Stripping water treatment vessel 9: Primarily treats organochlorine compounds such as 1-chloro-2,3-propanediol in the stripping water and extracts epichlorohydrin after the reaction, featuring heating, Stirring and depressurization functions; Reclaimed water tank 10: mainly used to store the treated stripped aqueous phase; Reclaimed water pump 11: mainly used to send reclaimed water to the refining kettle; Toluene resin clarifying tank 12: mainly used to store the treated stripped toluene phase; Clarifying pump 13: mainly used to send the stripped toluene phase to the refining kettle; Refining kettle 14: has heating and stirring functions, mainly used for further refining of epoxy resin; Filter 15: mainly used to filter impurities in toluene resin; Benzene removal kettle 16: has heating, stirring, and depressurization functions, mainly used to remove toluene from toluene epoxy resin; Reactor 20: has heating, cooling, stirring, and depressurization functions, mainly used to dissolve reactants and provide conditions for the main reaction; Wastewater tank 21: used to store high-salt wastewater.

[0049] When the above apparatus is in operation, the reaction raw materials first enter the reactor 20 through the feed pipe 19 for the main reaction. The mixture of epichlorohydrin and water vapor produced during the reaction enters the water separator 1 for settling and stratification. The separated upper aqueous phase is transported to the reaction tank 3 by the water pump 2 for temporary storage, while the lower epichlorohydrin phase is returned to the reactor 20 for reuse. The aqueous phase in the reaction tank 3 is sent to the stripping tower 5 by the water pump 4 according to the production schedule.

[0050] In stripping tower 5, recyclable epichlorohydrin is further removed from the water by steam stripping. The gas-phase mixture at the top of the stripping tower enters water separator 6 for further stratification, the epichlorohydrin is recycled, and the treated stripped water, rich in organic chlorine, enters the post-stripping water tank 7 for temporary storage. The stripped water in the post-stripping water tank 7 is pumped into the stripped water treatment vessel 9 by stripped water pump 8.

[0051] In the stripping water treatment vessel 9, alkaline solution and an accelerator are added through alkaline solution pipeline 17, and the mixture is heated and kept at a constant temperature to carry out the alkaline dechlorination reaction. After the reaction, toluene is added through toluene pipeline 18 for extraction, and the mixture is allowed to stand and separate into layers. The upper toluene phase containing glycidol is discharged from the middle of the vessel and temporarily stored in the toluene resin clear liquid tank 12; the lower purified aqueous phase is discharged from the bottom of the vessel and temporarily stored in the recycled water tank 10.

[0052] The toluene phase in the toluene resin clearing tank 12 is transported to the refining tank 14 via the clearing pump 13. Simultaneously, the reaction liquid after the reaction in the reactor 20 is sent to the refining tank 14. The purified aqueous phase in the recycled water tank 10 is also sent to the refining tank 14 via the recycled water pump 11 as washing water for the refining section.

[0053] In the refining reactor 14, the material undergoes refining operations such as adding alkali, adding catalyst, and multi-step water washing, followed by settling and stratification. Depending on the water quality, the lower aqueous phase is either discharged into wastewater tank 21 to collect high-salt wastewater, or returned to reclaimed water tank 10 for recycling. The upper toluene resin phase is discharged from the lower part of the refining reactor 14 and enters filter 15 to filter impurities. The filtered clear liquid enters the benzene removal reactor 16. In the benzene removal reactor 16, toluene is removed by depressurization and heating, ultimately yielding the epoxy resin product. The entire process, through the coordinated operation of various pumps, tanks, and reactors, achieves closed-loop treatment and resource recycling of the stripping water.

[0054] Example 1 The epoxy resin production process for improving the recycling rate of stripping water according to the present invention includes the following steps: a. Reaction: In reactor 20, at an initial temperature of 40℃, bisphenol A and epichlorohydrin were added, making the mass ratio of bisphenol A to epichlorohydrin 1:2.0. The mixture was kept at this temperature and stirred for 30 minutes under anaerobic conditions. The temperature of reactor 20 was then increased to 50℃, and a benzyltriethylammonium chloride solution in epichlorohydrin (mass ratio of bisphenol A, epichlorohydrin, and benzyltriethylammonium chloride 1:0.03:0.01) was added. The mixture was stirred until homogeneous and reacted for 2 hours. Then, under conditions of 20 kPa and 60℃, 40% NaO was added dropwise. Solution H is added to reactor 20 and added dropwise over 3 hours. The distillation reaction is carried out under a negative pressure of 20 kPa. During the reaction, epichlorohydrin and water are recovered to water separator 1. Epichlorohydrin is returned to reactor 20, and the aqueous phase is pumped to reaction water tank 3 and then into stripping tower 5. After the main reaction is completed, the reactor is heated to 120°C and the reactor pressure reaches 1 kPa. Steam is bubbled for 30 minutes. Using the azeotropic principle, the epichlorohydrin and water generated by steam bubbling in the system are recovered to water separator 1. The water in the upper layer of water separator 1 is pumped into reaction water tank 3.

[0055] b. Collection of stripping water: The aqueous phase from vacuum distillation in step a and the bubbling azeotropic aqueous phase are collected in stripping tower 5. The aqueous phase after stripping is the stripping water, which contains organochlorine compounds such as 1-chloro-2,3-propanediol, with a total chlorine content of 1000 ppm and a pH of 7. This stripping water is sent to the stripping water treatment vessel 9 through water separator 6 and stripping water tank 7 for the next step of alkaline dechlorination treatment.

[0056] c. Alkali dechlorination: Add 10wt% NaOH solution to the stripping water treatment vessel 9, adjust the pH to 8, and add the selective accelerator tert-butanol (the mass of the accelerator added is 0.5% of the mass of the stripping water). Heat to 60℃ and keep the reaction at this temperature for 0.5h.

[0057] d. Toluene extraction: Toluene is added to the stripped water after step c. The volume of toluene added is 0.2 times the volume of the stripped water. Stir thoroughly for 10 minutes, let stand to separate the layers, and obtain the purified water phase and the toluene phase. The total chlorine in the purified water phase is significantly reduced (inorganic chloride ion content ≤500ppm, organic chlorine not detected). The purified water phase is separated and sent to the reclaimed water tank for reuse.

[0058] e. Refining: The resin liquid in the reaction vessel 20 of step a is pumped into the refining vessel 14, and the toluene phase obtained in step d (the mass ratio of bisphenol A to toluene phase is 1:1.9) is added to the refining vessel 14. The temperature is raised to 70°C for reaction. After the reaction is completed, the reaction liquid is separated by stepwise settling. The toluene resin is filtered and pumped into the benzene removal vessel 16. The pressure is reduced to 1 kPa and the temperature is raised to 130°C to recover toluene. Then, the resin is steamed for 30 min to obtain the epoxy resin product. The stepwise settling and separation method is as follows: Step 1: Add benzyltriethylammonium chloride (the mass ratio of bisphenol A to benzyltriethylammonium chloride is 1:0.0005) and 10% NaOH solution (the mass ratio of bisphenol A to 10% alkaline solution is 1:0.17) to the reaction solution in refining vessel 14, stir the reaction for 2 hours, and let it stand to separate the liquids; Step 2: Add recycled water (the mass ratio of bisphenol A to recycled water is 1:1.1), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to wastewater tank 21. Step 3: Add a 1% (w / w) aqueous solution of disodium hydrogen phosphate to the organic phase (the mass ratio of bisphenol A to the 1% (w / w) aqueous solution of disodium hydrogen phosphate is 1:0.45), stir for 10 min, let stand and separate the liquids, and send the lower aqueous phase to the water tank 10. Step 4: Add pure water to the organic phase (the mass ratio of bisphenol A to pure water is 1:0.55), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the recycling tank 10. Step 5: The organic phase is heated to 110°C to remove water, then filtered to obtain toluene resin.

[0059] Example 2 The epoxy resin production process for improving the recycling rate of stripping water according to the present invention includes the following steps: a. Reaction: In reactor 20, at an initial temperature of 45℃, bisphenol A and epichlorohydrin were added, making the mass ratio of bisphenol A to epichlorohydrin 1:3.0. The mixture was kept at this temperature and stirred for 30 minutes under anaerobic conditions. The temperature of reactor 20 was then increased to 50℃, and a benzyltriethylammonium chloride solution in epichlorohydrin (mass ratio of bisphenol A, epichlorohydrin, and benzyltriethylammonium chloride 1:0.05:0.02) was added. The mixture was stirred until homogeneous and reacted for 3 hours. Then, under conditions of 23 kPa and 65℃, 50% NaO was added dropwise. Solution H is added to reactor 20 and added dropwise over 5 hours. The distillation reaction is carried out under a negative pressure of 23 kPa. During the reaction, epichlorohydrin and water are recovered to water separator 1. Epichlorohydrin is returned to reactor 20, and the aqueous phase is pumped to reaction water tank 3 and then into stripping tower 5. After the main reaction is completed, the reactor is heated to 130°C and the reactor pressure reaches 5 kPa. Steam is bubbled for 60 minutes. Using the azeotropic principle, the epichlorohydrin and water generated by steam bubbling in the system are recovered to water separator 1. The water in the upper layer of water separator 1 is pumped into reaction water tank 3.

[0060] b. Collection of stripping water: The aqueous phase from vacuum distillation in step a and the bubbling azeotropic aqueous phase are collected in stripping tower 5. The aqueous phase after stripping is the stripping water, which contains organochlorine compounds such as 1-chloro-2,3-propanediol, with a total chlorine content of 2000 ppm and a pH of 9. This stripping water is sent to the stripping water treatment vessel 9 through water separator 6 and stripping water tank 7 for the next step of alkaline dechlorination treatment.

[0061] c. Alkali dechlorination: Add 10wt% NaOH solution to stripping water treatment vessel 9, adjust the pH to 13, and add isopropanol as a selective promoter (the mass of the promoter added is 1% of the mass of stripping water). Heat to 110℃ and keep the reaction at this temperature for 3 hours.

[0062] d. Toluene extraction: Toluene is added to the stripped water after step c, with the volume of toluene being 1 times that of the stripped water. The mixture is stirred thoroughly for 60 minutes to transfer the glycidol from the aqueous phase to the toluene phase. After standing and separating the layers, a purified aqueous phase and a toluene phase are obtained. The total chlorine in the purified aqueous phase is significantly reduced (inorganic chloride ion content ≤500ppm, organic chlorine not detected). The toluene phase contains toluene and the extracted glycidol. The purified aqueous phase is separated and sent to a reclaimed water tank for reuse.

[0063] e. Refining: The resin liquid in the reaction vessel 20 of step a is pumped into the refining vessel 14, and the toluene phase obtained in step d (the mass ratio of bisphenol A to toluene phase is 1:1.9) is added to the refining vessel 14. The temperature is raised to 90°C for reaction. After the reaction is completed, the reaction liquid is separated by stepwise settling. The toluene resin is filtered and pumped into the benzene removal vessel 16. The pressure is reduced to 5 kPa and the temperature is raised to 150°C to recover toluene. Then, the mixture is steamed for 60 min to obtain the epoxy resin product. The stepwise settling and separation method is as follows: Step 1: Add benzyltriethylammonium chloride (the mass ratio of bisphenol A to benzyltriethylammonium chloride is 1:0.0005) and 15% NaOH solution (the mass ratio of bisphenol A to 15% alkaline solution is 1:0.11) to the reaction solution in refining vessel 14, stir the reaction for 3 hours, and let it stand to separate the liquids; Step 2: Add recycled water (the mass ratio of bisphenol A to recycled water is 1:1.1), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to wastewater tank 21. Step 3: Add a 1% (w / w) aqueous solution of disodium hydrogen phosphate to the organic phase (the mass ratio of bisphenol A to the 1% (w / w) aqueous solution of disodium hydrogen phosphate is 1:0.45), stir for 10 min, let stand and separate the liquids, and send the lower aqueous phase to the water tank 10. Step 4: Add pure water to the organic phase (the mass ratio of bisphenol A to pure water is 1:0.55), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the recycling tank 10. Step 5: Heat the organic phase to 120°C, perform dehydration, filter, and obtain toluene resin.

[0064] Example 3 The epoxy resin production process for improving the recycling rate of stripping water according to the present invention includes the following steps: a. Reaction: In reactor 20, at an initial temperature of 40℃, bisphenol A and epichlorohydrin were added, making the mass ratio of bisphenol A to epichlorohydrin 1:2.4. The mixture was kept at this temperature and stirred for 30 minutes under anaerobic conditions. The temperature of reactor 20 was then increased to 50℃, and a benzyltriethylammonium chloride solution in epichlorohydrin (mass ratio of bisphenol A, epichlorohydrin, and benzyltriethylammonium chloride 1:0.04:0.014) was added. The mixture was stirred until homogeneous and reacted for 3 hours. Then, under conditions of 21 kPa and 62℃, 44% NaOH was added dropwise. The solution is added to reactor 20, with a dripping time of 3.5 hours. The distillation reaction is carried out under a negative pressure of 21 kPa. During the reaction, epichlorohydrin and water are recovered to water separator 1. Epichlorohydrin is returned to reactor 20, and the aqueous phase is pumped to reaction water tank 3 and then into stripping tower 5. After the main reaction is completed, the reactor is heated to 123°C and the reactor pressure reaches 3 kPa. Steam is bubbled for 40 minutes. The epichlorohydrin and water generated by steam bubbling in the system are recovered to water separator 1 using the azeotropic principle. The water in the upper layer of water separator 1 is pumped into reaction water tank 3.

[0065] b. Collection of stripping water: The aqueous phase from vacuum distillation in step a and the bubbling azeotropic aqueous phase are collected in stripping tower 5. The aqueous phase after stripping is the stripping water, which contains organochlorine compounds such as 1-chloro-2,3-propanediol, with a total chlorine content of 1200 ppm and a pH of 8. This stripping water is sent to the stripping water treatment vessel 9 through water separator 6 and stripping water tank 7 for the next step of alkaline dechlorination treatment.

[0066] c. Alkali dechlorination: Add 10wt% NaOH solution to stripping water treatment vessel 9, adjust the pH to 11, and add selective accelerator ethylene glycol monomethyl ether (the mass of the accelerator added is 0.8% of the mass of stripping water). Heat to 60℃ and keep the reaction at this temperature for 0.5h.

[0067] d. Toluene extraction: Toluene is added to the stripped water after step c. The volume of toluene added is 0.2 times the volume of the stripped water. Stir thoroughly for 10 minutes, let stand to separate the layers, and obtain the purified water phase and the toluene phase. The total chlorine in the purified water phase is significantly reduced (inorganic chloride ion content ≤500ppm, organic chlorine not detected). The purified water phase is separated and sent to the reclaimed water tank for reuse.

[0068] e. Refining: The resin liquid in the reaction vessel 20 of step a is pumped into the refining vessel 14, and the toluene phase obtained in step d (the mass ratio of bisphenol A to toluene phase is 1:1.9) is added to the refining vessel 14. The temperature is raised to 75°C for reaction. After the reaction is completed, the reaction liquid is separated by stepwise settling. The toluene resin is filtered and pumped into the benzene removal vessel 16. The pressure is reduced to 3 kPa and the temperature is raised to 140°C to recover toluene. Then, the resin is steamed for 40 min to obtain the epoxy resin product. The stepwise settling and separation method is as follows: Step 1: Add benzyltriethylammonium chloride (the mass ratio of bisphenol A to benzyltriethylammonium chloride is 1:0.0005) and 13% NaOH solution (the mass ratio of bisphenol A to 13% NaOH solution is 1:0.17) to the reaction solution in refining vessel 14, stir and react for 2.5 hours, then let stand and separate the contents. Step 2: Add recycled water (the mass ratio of bisphenol A to recycled water is 1:1.1), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to wastewater tank 21. Step 3: Add a 1.2% (w / w) aqueous solution of disodium hydrogen phosphate to the organic phase (the mass ratio of bisphenol A to the 1.2% (w / w) aqueous solution of disodium hydrogen phosphate is 1:0.45), stir for 10 min, let stand and separate the liquids, and send the lower aqueous phase to the water tank 10. Step 4: Add pure water to the organic phase (the mass ratio of bisphenol A to pure water is 1:0.55), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the recycling tank 10. Step 5: The organic phase is heated to 115°C to remove water, then filtered to obtain toluene resin.

[0069] Example 4 The epoxy resin production process for improving the recycling rate of stripping water according to the present invention includes the following steps: a. Reaction: In reactor 20, at an initial temperature of 43℃, bisphenol A and epichlorohydrin were added, making the mass ratio of bisphenol A to epichlorohydrin 1:2.8. The mixture was kept at this temperature and stirred for 30 minutes under anaerobic conditions. The temperature of reactor 20 was then increased to 50℃, and a benzyltriethylammonium chloride solution in epichlorohydrin (mass ratio of bisphenol A, epichlorohydrin, and benzyltriethylammonium chloride 1:0.04:0.018) was added. The mixture was stirred until homogeneous and reacted for 2.7 hours. Then, under conditions of 22 kPa and 64℃, 48% NaO was added dropwise. H solution is added to reactor 20, with a dropping time of 4.5 h. Distillation reaction is carried out under a negative pressure of 22 kPa. During the reaction, epichlorohydrin and water are recovered to water separator 1. Epichlorohydrin is returned to reactor 20, and the aqueous phase is pumped to reaction water tank 3 and then into stripping tower 5. After the main reaction is completed, the reactor is heated to 128°C and the reactor pressure reaches 4 kPa. Steam is bubbled for 50 min. Using the azeotropic principle, the epichlorohydrin and water generated by steam bubbling in the system are recovered to water separator 1. The water in the upper layer of water separator 1 is pumped into reaction water tank 3.

[0070] b. Collection of stripping water: The aqueous phase from vacuum distillation in step a and the bubbling azeotropic aqueous phase are collected in stripping tower 5. The aqueous phase after stripping is the stripping water, which contains organochlorine compounds such as 1-chloro-2,3-propanediol, with a total chlorine content of 1800 ppm and a pH of 8.5. This stripping water is sent to the stripping water treatment vessel 9 through water separator 6 and stripping water tank 7 for the next step of alkaline dechlorination treatment.

[0071] c. Alkali dechlorination: Add 10wt% NaOH solution to the stripping water treatment vessel 9, adjust the pH to 12, and add the selective accelerator tert-butanol (the mass of the accelerator added is 0.8% of the mass of the stripping water). Heat to 90℃ and keep the reaction at this temperature for 2.5h.

[0072] d. Toluene extraction: Toluene is added to the stripped water after step c, with the volume of toluene being 0.8 times the volume of the stripped water. The mixture is stirred thoroughly for 50 minutes to transfer the glycidol from the aqueous phase to the toluene phase. After standing and separating the layers, a purified aqueous phase and a toluene phase are obtained. The total chlorine in the purified aqueous phase is significantly reduced (inorganic chloride ion content ≤500ppm, organic chlorine not detected). The toluene phase contains toluene and the extracted glycidol. The purified aqueous phase is separated and sent to a reclaimed water tank for reuse.

[0073] e. Refining: The resin liquid in the reaction vessel 20 of step a is pumped into the refining vessel 14, and the toluene phase obtained in step d (the mass ratio of bisphenol A to toluene phase is 1:1.9) is added to the refining vessel 14. The temperature is raised to 85°C for reaction. After the reaction is completed, the reaction liquid is separated by stepwise settling. The toluene resin is filtered and pumped into the benzene removal vessel 16. The pressure is reduced to 4 kPa and the temperature is raised to 140°C to recover toluene. Then, the mixture is steamed for 45 min to obtain the epoxy resin product. The stepwise settling and separation method is as follows: Step 1: Add benzyltriethylammonium chloride (the mass ratio of bisphenol A to benzyltriethylammonium chloride is 1:0.0005) and 14% NaOH solution (the mass ratio of bisphenol A to 14% NaOH solution is 1:0.13) to the reaction solution in refining vessel 14. Stir the reaction for 2 hours and let it stand to separate the liquids. Step 2: Add recycled water (the mass ratio of bisphenol A to recycled water is 1:1.1), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to wastewater tank 21. Step 3: Add a 1% (w / w) aqueous solution of disodium hydrogen phosphate to the organic phase (the mass ratio of bisphenol A to the 1% (w / w) aqueous solution of disodium hydrogen phosphate is 1:0.45), stir for 10 min, let stand and separate the liquids, and send the lower aqueous phase to the water tank 10. Step 4: Add pure water to the organic phase (the mass ratio of bisphenol A to pure water is 1:0.55), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the recycling tank 10. Step 5: The organic phase is heated to 118°C to remove water, then filtered to obtain toluene resin.

[0074] The apparatus used in the following comparative examples is similar to that of the present invention. The apparatus can be implemented by simply switching the pipeline according to the process conditions of the comparative examples.

[0075] Comparative Example 1 A method for preparing an epoxy resin includes the following steps: a. Reaction: In a reaction vessel, at an initial temperature of 40℃, bisphenol A and epichlorohydrin were added, making the mass ratio of bisphenol A to epichlorohydrin 1:2.0. The mixture was kept at this temperature and stirred for 30 minutes under anaerobic conditions. The temperature of the reaction vessel was then increased to 50℃, and a benzyltriethylammonium chloride solution in epichlorohydrin (mass ratio of bisphenol A, epichlorohydrin, and benzyltriethylammonium chloride 1:0.03:0.01) was added. The mixture was stirred until homogeneous and reacted for 2 hours. Then, under conditions of 20 kPa and 60℃, a 40% (by mass) solution was added dropwise. Add NaOH solution to the reactor and drop it over 3 hours. The distillation reaction is carried out under a negative pressure of 20 kPa. During the reaction, epichlorohydrin and water are recovered to the water separator. Epichlorohydrin is returned to the reactor, and the aqueous phase is pumped to the reaction water tank and then into the stripping tower. After the main reaction is completed, the reactor is heated to 120°C and the reactor pressure reaches 1 kPa. Steam is bubbled for 30 minutes. Using the azeotropic principle, the epichlorohydrin and the water generated by steam bubbling in the system are recovered to the water separator. The water in the upper layer of the water separator is pumped into the reaction water tank.

[0076] b. Collection of stripping water: Collect the aqueous phase from the vacuum distillation in step a and the bubbling azeotropic aqueous phase in the stripping tower. The aqueous phase after stripping is the stripping water, which contains organochlorine compounds such as 1-chloro-2,3-propanediol, with a total chlorine content of 1000 ppm and a pH of 7. This stripping water is then sent for the next step of alkaline dechlorination treatment.

[0077] c. Alkali dechlorination: Add 10wt% NaOH solution to the stripping water treatment vessel, adjust the pH to 8, heat to 60℃, and keep the reaction at this temperature for 0.5h.

[0078] d. Toluene extraction: Toluene is added to the stripped water after step c. The volume of toluene added is 0.2 times the volume of the stripped water. Stir thoroughly for 10 minutes, let stand to separate the layers, and obtain the purified water phase and the toluene phase. The total chlorine in the purified water phase is significantly reduced (inorganic chloride ion content ≤500ppm, organic chlorine not detected). The purified water phase is separated and sent to the reclaimed water tank for reuse.

[0079] e. Refining: The resin liquid in the reaction vessel of step a is pumped into the refining vessel, and the toluene phase obtained in step d (the mass ratio of bisphenol A to toluene phase is 1:1.9) is added to the refining vessel. The temperature is raised to 70°C for reaction. After the reaction is completed, the reaction liquid is separated by stepwise settling. The toluene resin is filtered and pumped into the benzene removal vessel. The pressure is reduced to 1 kPa and the temperature is raised to 130°C to recover the toluene. Then, the mixture is steamed for 30 minutes to obtain the epoxy resin product. The stepwise settling and separation method is as follows: Step 1: Add benzyltriethylammonium chloride (the mass ratio of bisphenol A to benzyltriethylammonium chloride is 1:0.0005) and 10% NaOH solution (the mass ratio of bisphenol A to 10% NaOH solution is 1:0.17) to the reaction solution, stir for 2 hours, and let stand to separate the contents. Step 2: Add recycled water (the mass ratio of bisphenol A to recycled water is 1:1.1), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the wastewater tank. Step 3: Add a 1% (w / w) aqueous solution of disodium hydrogen phosphate to the organic phase (the mass ratio of bisphenol A to the 1% (w / w) aqueous solution of disodium hydrogen phosphate is 1:0.45), stir for 10 min, let stand and separate the liquids, and send the lower aqueous phase to the water recycling tank. Step 4: Add pure water to the organic phase (the mass ratio of bisphenol A to pure water is 1:0.55), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the recycling tank. Step 5: The organic phase is heated to 110°C to remove water, then filtered to obtain toluene resin.

[0080] Comparative Example 2 A method for preparing an epoxy resin includes the following steps: a. Reaction: In a reaction vessel, at an initial temperature of 45℃, bisphenol A and epichlorohydrin are added, making the mass ratio of bisphenol A to epichlorohydrin 1:3.0. The mixture is kept at this temperature and stirred for 30 minutes under anaerobic conditions. The temperature of the reaction vessel is then increased to 50℃, and a benzyltriethylammonium chloride solution in epichlorohydrin (mass ratio of bisphenol A, epichlorohydrin, and benzyltriethylammonium chloride 1:0.05:0.02) is added. The mixture is stirred until homogeneous and reacted for 3 hours. Under conditions of 23 kPa and 65℃, a 50% (w / w) NaOH solution is added dropwise to the reaction vessel. The distillation reaction was carried out under a negative pressure of 23 kPa for 5 hours. During the reaction, epichlorohydrin and water were recovered to the water separator. Epichlorohydrin was returned to the reactor, and the aqueous phase was pumped to the reaction water tank and then into the stripping tower. After the main reaction was completed, the reactor was heated to 130°C and the reactor pressure reached 5 kPa. Steam was bubbled for 60 minutes. Using the azeotropic principle, the epichlorohydrin and the water generated by steam bubbling in the system were recovered to the water separator. The water in the upper layer of the water separator was pumped into the reaction water tank. According to the production schedule, the reaction water in the reaction water tank was pumped into the stripping tower for stripping.

[0081] b. Collection of stripping water: Collect the aqueous phase from the vacuum distillation in step a and the bubbling azeotropic aqueous phase in the stripping tower. The aqueous phase after stripping is the stripping water, which contains organochlorine compounds such as 1-chloro-2,3-propanediol, with a total chlorine content of 2000 ppm and a pH of 9. This stripping water is then sent for the next step of alkaline dechlorination treatment.

[0082] c. Alkali dechlorination: Add isopropanol (1% of the mass of the stripped water) to the stripped water treatment vessel and heat to 110°C. Keep the temperature for 3 hours.

[0083] d. Toluene extraction: Toluene is added to the stripped water after step c, with the volume of toluene being 1 times that of the stripped water. The mixture is stirred thoroughly for 60 minutes to transfer the glycidol from the aqueous phase to the toluene phase. After standing and separating the layers, a purified aqueous phase and a toluene phase are obtained. The total chlorine in the purified aqueous phase is significantly reduced (inorganic chloride ion content ≤500ppm, organic chlorine not detected). The toluene phase contains toluene and the extracted glycidol. The purified aqueous phase is separated and sent to a reclaimed water tank for reuse.

[0084] e. Refining: The resin liquid in the reaction vessel of step a is pumped into the refining vessel, and the toluene phase obtained in step d (the mass ratio of bisphenol A to toluene phase is 1:1.9) is added to the refining vessel. The temperature is raised to 90°C for reaction. After the reaction is completed, the reaction liquid is separated by stepwise settling. The toluene resin is filtered and pumped into the benzene removal vessel. The pressure is reduced to 5 kPa and the temperature is raised to 150°C to recover the toluene. Then, the mixture is steamed for 60 min to obtain the epoxy resin product. The stepwise settling and separation method is as follows: Step 1: Add benzyltriethylammonium chloride (the mass ratio of bisphenol A to benzyltriethylammonium chloride is 1:0.0005) and 15% NaOH solution (the mass ratio of bisphenol A to 15% NaOH solution is 1:0.11) to the reaction solution, stir for 3 hours, and let stand to separate the liquids. Step 2: Add recycled water (the mass ratio of bisphenol A to recycled water is 1:1.1), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the wastewater tank. Step 3: Add a 1% (w / w) aqueous solution of disodium hydrogen phosphate to the organic phase (the mass ratio of bisphenol A to the 1% (w / w) aqueous solution of disodium hydrogen phosphate is 1:0.45), stir for 10 min, let stand and separate the liquids, and send the lower aqueous phase to the water recycling tank. Step 4: Add pure water to the organic phase (the mass ratio of bisphenol A to pure water is 1:0.55), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the recycling tank. Step 5: Heat the organic phase to 120°C, perform dehydration, filter, and obtain toluene resin.

[0085] Comparative Example 3 A method for preparing an epoxy resin includes the following steps: a. Reaction: In a reaction vessel, at an initial temperature of 40℃, bisphenol A and epichlorohydrin are added, making the mass ratio of bisphenol A to epichlorohydrin 1:2.4. The mixture is kept at this temperature and stirred for 30 minutes under anaerobic conditions. The temperature of the reaction vessel is then increased to 50℃, and a benzyltriethylammonium chloride solution in epichlorohydrin (mass ratio of bisphenol A, epichlorohydrin, and benzyltriethylammonium chloride 1:0.04:0.014) is added. The mixture is stirred until homogeneous and reacted for 3 hours. Under conditions of 21 kPa and 62℃, a 44% (w / w) NaOH solution is added dropwise to the reaction vessel. The distillation reaction was carried out under a negative pressure of 21 kPa for 3.5 hours. During the reaction, epichlorohydrin and water were recovered to the water separator. The epichlorohydrin was returned to the reactor, and the aqueous phase was pumped to the reaction water tank and then into the stripping tower. After the main reaction was completed, the reactor was heated to 123°C and the reactor pressure reached 3 kPa. Steam was bubbled for 40 minutes. The epichlorohydrin and the water generated by steam bubbling in the system were recovered to the water separator using the azeotropic principle. The water in the upper layer of the water separator was pumped into the reaction water tank. According to the production schedule, the reaction water in the reaction water tank was pumped into the stripping tower for stripping.

[0086] b. Collection of stripping water: Collect the aqueous phase from the vacuum distillation in step a and the bubbling azeotropic aqueous phase in the stripping tower. The aqueous phase after stripping is the stripping water, which contains organochlorine compounds such as 1-chloro-2,3-propanediol, with a total chlorine content of 1200 ppm and a pH of 8. This stripping water is then sent for the next step of alkaline dechlorination treatment.

[0087] c. Alkali dechlorination: Add 10wt% NaOH solution to the stripping water treatment vessel, adjust the pH to 11, and add the selective accelerator ethylene glycol monomethyl ether (the mass of the accelerator added is 0.8% of the mass of the stripping water). Heat to 60℃ and keep the reaction at this temperature for 0.5h.

[0088] d. The treated stripped water is transferred to a reclaimed water tank for reuse.

[0089] e. Refining: The resin liquid in the reaction vessel of step a is pumped into the refining vessel, and fresh toluene is added to the refining vessel so that the mass ratio of bisphenol A to toluene is 1:1.9. The temperature is raised to 75°C for reaction. After the reaction is completed, the reaction liquid is separated by stepwise settling. The toluene resin is filtered and pumped into the benzene removal vessel, the pressure is reduced to 3 kPa, the temperature is raised to 140°C, the toluene is recovered, and then steam is bubbled for 40 min to obtain the epoxy resin product. The stepwise settling and separation method is as follows: Step 1: Add benzyltriethylammonium chloride (the mass ratio of bisphenol A to benzyltriethylammonium chloride is 1:0.0005) and 13% NaOH solution (the mass ratio of bisphenol A to 13% NaOH solution is 1:0.17) to the reaction solution, stir the reaction for 2.5 hours, and let it stand to separate the liquids; Step 2: Add recycled water (the mass ratio of bisphenol A to recycled water is 1:1.1), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the wastewater tank. Step 3: Add a 1.2% (w / w) aqueous solution of disodium hydrogen phosphate to the organic phase (the mass ratio of bisphenol A to the 1.2% (w / w) aqueous solution of disodium hydrogen phosphate is 1:0.45), stir for 10 min, let stand and separate the liquids, and send the lower aqueous phase to the water recycling tank. Step 4: Add pure water to the organic phase (the mass ratio of bisphenol A to pure water is 1:0.55), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the recycling tank. Step 5: The organic phase is heated to 115°C to remove water, then filtered to obtain toluene resin.

[0090] Comparative Example 4 A method for preparing an epoxy resin includes the following steps: a. Reaction: In a reaction vessel, at an initial temperature of 43℃, bisphenol A and epichlorohydrin were added, making the mass ratio of bisphenol A to epichlorohydrin 1:2.8. The mixture was kept at this temperature and stirred for 30 minutes under anaerobic conditions. The temperature of the reaction vessel was then increased to 50℃, and a benzyltriethylammonium chloride solution in epichlorohydrin (mass ratio of bisphenol A, epichlorohydrin, and benzyltriethylammonium chloride 1:0.04:0.018) was added. The mixture was stirred until homogeneous and reacted for 2.7 hours. Under conditions of 22 kPa and 64℃, a 48% (w / w) NaOH solution was added dropwise to the reaction vessel. The addition time is 4.5 hours, and the distillation reaction is carried out under a negative pressure of 22 kPa. During the reaction, epichlorohydrin and water are recovered to the water separator, and the epichlorohydrin is returned to the reactor. The aqueous phase is pumped to the reaction water tank and then into the stripping tower. After the main reaction is completed, the reactor is heated to 128°C and the reactor pressure reaches 4 kPa. Steam is bubbled for 50 minutes. Using the azeotropic principle, the epichlorohydrin and the water generated by steam bubbling in the system are recovered to the water separator. The water in the upper layer of the water separator is pumped into the reaction water tank. According to the production schedule, the reaction water in the reaction water tank is pumped into the stripping tower for stripping.

[0091] b. Collect stripping water: Collect the aqueous phase from the vacuum distillation in step a and the bubbling azeotropic aqueous phase in the stripping tower. The aqueous phase after stripping is the stripping water, which contains organochlorine compounds such as 1-chloro-2,3-propanediol, with a total chlorine content of 1800 ppm and a pH of 8.5. The stripping water is then transferred to a reclaimed water tank for reuse.

[0092] c. Refining: The resin liquid in the reaction vessel of step a is pumped into the refining vessel, and fresh toluene is added to the refining vessel so that the mass ratio of bisphenol A to toluene is 1:1.9. The temperature is raised to 85°C for reaction. After the reaction is completed, the reaction liquid is separated by stepwise settling. The toluene resin is filtered and pumped into the benzene removal vessel, the pressure is reduced to 4 kPa, the temperature is raised to 140°C, the toluene is recovered, and then steam is bubbled for 45 min to obtain the epoxy resin product. The stepwise settling and separation method described above: Step 1: Add benzyltriethylammonium chloride (the mass ratio of bisphenol A to benzyltriethylammonium chloride is 1:0.0005) and 14% NaOH solution (the mass ratio of bisphenol A to 14% NaOH solution is 1:0.13) to the reaction solution, stir for 2 hours, and let stand to separate the contents. Step 2: Add recycled water (the mass ratio of bisphenol A to recycled water is 1:1.1), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the wastewater tank. Step 3: Add a 1% (w / w) aqueous solution of disodium hydrogen phosphate to the organic phase (the mass ratio of bisphenol A to 1% (w / w) aqueous solution of disodium hydrogen phosphate is 1:0.45), stir for 10 min, let stand and separate the liquids, and send the lower aqueous phase to the recycling tank. Step 4: Add pure water to the organic phase (the mass ratio of bisphenol A to pure water is 1:0.55), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the recycling tank. Step 5: The organic phase is heated to 118°C to remove water, then filtered to obtain toluene resin.

[0093] Comparative Example 5 A method for preparing an epoxy resin includes the following steps: a. Reaction: In a reaction vessel, at an initial temperature of 43℃, bisphenol A and epichlorohydrin were added, making the mass ratio of bisphenol A to epichlorohydrin 1:2.8. The mixture was kept at this temperature and stirred for 30 minutes under anaerobic conditions. The temperature of the reaction vessel was then increased to 50℃, and a benzyltriethylammonium chloride solution in epichlorohydrin (mass ratio of bisphenol A, epichlorohydrin, and benzyltriethylammonium chloride 1:0.04:0.018) was added. The mixture was stirred until homogeneous and reacted for 2.7 hours. Under conditions of 22 kPa and 64℃, a 48% (w / w) NaOH solution was added dropwise to the reaction vessel. The addition time is 4.5 hours, and the distillation reaction is carried out under a negative pressure of 22 kPa. During the reaction, epichlorohydrin and water are recovered to the water separator, and the epichlorohydrin is returned to the reactor. The aqueous phase is pumped to the reaction water tank and then into the stripping tower. After the main reaction is completed, the reactor is heated to 128°C and the reactor pressure reaches 4 kPa. Steam is bubbled for 50 minutes. Using the azeotropic principle, the epichlorohydrin and the water generated by steam bubbling in the system are recovered to the water separator. The water in the upper layer of the water separator is pumped into the reaction water tank. According to the production schedule, the reaction water in the reaction water tank is pumped into the stripping tower for stripping.

[0094] b. Collection of stripping water: Collect the aqueous phase from the vacuum distillation in step a and the bubbling azeotropic aqueous phase in the stripping tower. The aqueous phase after stripping is the stripping water, which contains organochlorine compounds such as 1-chloro-2,3-propanediol, with a total chlorine content of 1800 ppm and a pH of 8.5. The stripping water is treated as wastewater.

[0095] c. Refining: The resin liquid in the reaction vessel of step a is pumped into the refining vessel, and fresh toluene is added to the refining vessel so that the mass ratio of bisphenol A to toluene is 1:1.9. The temperature is raised to 85°C for reaction. After the reaction is completed, the reaction liquid is separated by stepwise settling. The toluene resin is filtered and pumped into the benzene removal vessel, the pressure is reduced to 4 kPa, the temperature is raised to 140°C, the toluene is recovered, and then steam is bubbled for 45 min to obtain the epoxy resin product. The stepwise settling and separation method is as follows: Step 1: Add benzyltriethylammonium chloride (the mass ratio of bisphenol A to benzyltriethylammonium chloride is 1:0.0005) and 14% NaOH solution (the mass ratio of bisphenol A to 14% NaOH solution is 1:0.13) to the reaction solution, stir for 2 hours, and let stand to separate the contents. Step 2: Add recycled water (the mass ratio of bisphenol A to recycled water is 1:1.1), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the wastewater tank. Step 3: Add a 1% (w / w) aqueous solution of disodium hydrogen phosphate to the organic phase (the mass ratio of bisphenol A to the 1% (w / w) aqueous solution of disodium hydrogen phosphate is 1:0.45), stir for 10 min, let stand and separate the liquids, and send the lower aqueous phase to the water recycling tank. Step 4: Add pure water to the organic phase (the mass ratio of bisphenol A to pure water is 1:0.55), stir for 10 minutes, let stand and separate the liquids, and send the lower aqueous phase to the recycling tank. Step 5: The organic phase is heated to 118°C to remove water, then filtered to obtain toluene resin.

[0096] The test indicators of the epoxy resins prepared by the above examples and comparative examples are shown in Table 1 below.

[0097] Table 1. Epoxy Resin Testing Indicators

[0098] Based on the comparison of the test data of the examples and comparative examples in Table 1, it can be seen that: the addition of the accelerator significantly improves the removal of organochlorine from the stripping water. The total chlorine of the finished resin in Example 1 was 998 ppm, while in Comparative Example 1, without the addition of the accelerator, the total chlorine increased to 1058 ppm, and the hydrolyzed chlorine and viscosity also increased slightly. pH adjustment is crucial in the alkaline dechlorination process. In Example 2, the total chlorine was only 863 ppm under pH 13 conditions, while in Comparative Example 2, without pH adjustment and only with the addition of the accelerator, the total chlorine soared to 1442 ppm, indicating that an alkaline environment is key to the conversion of organochlorine. The toluene extraction step has a significant effect on maintaining the stability of resin viscosity. The resin viscosity of Example 3 after extraction was 10500 mPa·s, while in Comparative Example 3, the stripping water was directly reused without extraction, resulting in increased viscosity. The total chlorine content was 11500 mPa·s, but the difference in total chlorine was not significant, indicating that extraction mainly affects the removal of components such as glycidol, thus affecting viscosity. In Comparative Example 4, the stripping water was reused directly without any treatment, resulting in a total chlorine content of 1628 ppm and hydrolyzed chlorine content of 241 ppm in the finished product, which is much higher than the 842 ppm and 136 ppm in Example 4, proving that the combined process of alkaline dechlorination and toluene extraction of the present invention can effectively control the chlorine content of the product. In addition, Comparative Example 5 abandoned the reuse of stripping water, which reduced the total chlorine content to 847 ppm, but the wastewater generation was as high as 1.85 times the resin production, which is significantly higher than the 1.224 times of Example 4. This shows that the present invention significantly reduces wastewater discharge while ensuring product quality and achieves efficient recycling of stripping water.

Claims

1. An epoxy resin production process for improving the recycling rate of stripping water, characterized in that, Includes the following steps: a. Reaction: Bisphenol A and epichlorohydrin are added to a reaction vessel, and then a benzyltriethylammonium chloride epichlorohydrin solution is added to react. An alkaline solution is added, and the mixture is distilled under reduced pressure to separate water and epichlorohydrin. The epichlorohydrin is returned to the reaction vessel, and the aqueous phase finally enters the stripping tower. Bubbling is performed after the reaction is completed. b. Collect stripping water: Collect the aqueous phase from the vacuum distillation in step a and the bubbling azeotropic aqueous phase in the stripping tower, and then pump it into the stripping water treatment vessel. c. Alkaline dechlorination: Add an alkaline solution to the stripping water treatment vessel to adjust the pH to 8-13, add a selective accelerator, heat to 60-110℃, and maintain the temperature for reaction; the selective accelerator is one of tert-butanol, isopropanol, or ethylene glycol monomethyl ether, and the mass of the accelerator added is 0.5-1% of the mass of the stripping water; d. Toluene extraction: Add toluene to the stripped water after the reaction, stir thoroughly, let stand and separate into layers to obtain the purified aqueous phase and the toluene phase; e. Refining: The resin liquid in the reaction vessel of step a is pumped into the refining vessel, and the toluene phase obtained in step d is added. The temperature is raised to 70~90℃ for reaction. After the reaction is completed, the reaction solution is separated by stepwise settling to obtain toluene resin. Benzene is removed to obtain the epoxy resin product.

2. The epoxy resin production process for improving the recycling rate of stripping water according to claim 1, characterized in that, In step a, the initial temperature is 40-45℃, the mass ratio of bisphenol A to epichlorohydrin is 1:2.0-3.0, and the temperature is maintained for 30-45 minutes under anaerobic conditions. Then, the temperature is raised to 50-60℃ and an epichlorohydrin solution of benzyltriethylammonium chloride is added. The reaction is carried out for 2-3 hours.

3. The epoxy resin production process for improving the recycling rate of stripping water according to claim 2, characterized in that, In step a, the alkaline solution is added dropwise under controlled conditions of 20-23 kPa and 60-65°C. The mass fraction of the alkaline solution is 40-50%, and the dropwise addition time is 3-5 hours.

4. The epoxy resin production process for improving the recycling rate of stripping water according to claim 3, characterized in that, The bubbling conditions in step a are: pressure 1~5 kPa, temperature 120~130℃, and steam bubbling for 30~60 min.

5. The epoxy resin production process for improving the recycling rate of stripping water according to claim 1, characterized in that, The total chlorine content of the stripping water in the stripping water treatment vessel in step b is 1000~2000ppm, and the pH is 7~9.

6. The epoxy resin production process for improving the recycling rate of stripping water according to claim 1, characterized in that, In step d, the volume of toluene added is 0.2 to 1 times the volume of stripping water, and the mixture is stirred thoroughly for 10 to 60 minutes.

7. The epoxy resin production process for improving the recycling rate of stripping water according to claim 1, characterized in that, The specific steps for the step-by-step separation and settling in step e are as follows: Step 1: Add benzyltriethylammonium chloride and a 10-15% (w / w) alkaline solution to the reaction solution, and allow the mixture to stand and separate after the reaction. Step 2: Stir with recycled water for 10-30 minutes, let stand and separate the liquid to remove salt and impurities, and send the lower aqueous phase to the wastewater tank. Step 3: Add 1-2% (w / w) of disodium hydrogen phosphate aqueous solution, stir for 10-30 minutes, let stand and separate the liquids, and send the lower aqueous phase to the water tank for recycling. Step 4: Add pure water, stir for 10-30 minutes, let stand and separate the liquids, and send the lower aqueous phase to the recycling tank; Step 5: Heat to 110~120℃, remove water, filter, and obtain toluene resin.

8. The epoxy resin production process for improving the recycling rate of stripping water according to claim 7, characterized in that, In step e, benzene removal involves feeding toluene resin into a benzene removal reactor, reducing the pressure to 1-5 kPa, heating to 130-150°C, recovering toluene, and then bubbling with steam for 30-60 minutes to obtain the epoxy resin product.

9. A production apparatus used in the epoxy resin production process for improving the recycling rate of stripping water according to any one of claims 1-8, characterized in that, The reactor includes a reaction vessel (20) and a stripping tower (5). The top gas phase pipeline of the stripping tower (5) is connected to the second water separator (6). The second water separator (6) is connected to the stripped water tank (7). The stripped water tank (7) is connected to the stripped water treatment vessel (9). The bottom discharge pipeline of the stripped water treatment vessel (9) is connected to the recycled water tank (10). The recycled water tank (10) is connected to the refining vessel (14). The middle discharge pipeline of the stripped water treatment vessel (9) is connected to the toluene resin clear liquid tank (12). An alkaline solution pipeline (17) and a toluene pipeline (18) are provided on the stripped water treatment vessel (9).

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