Method for continuously producing VAE emulsion
By using continuous production methods and a DCS control system, the problems of low production efficiency and inconsistent quality of VAE emulsions have been solved, achieving efficient and stable VAE emulsion production, reducing energy consumption and safety hazards, and improving the degree of automation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YANTAI HUAGONG ENGINEERING TECHNOLOGY CO LTD
- Filing Date
- 2026-03-11
- Publication Date
- 2026-05-01
AI Technical Summary
Existing VAE emulsion production facilities employ intermittent or semi-intermittent processes, resulting in low production efficiency, inconsistent product quality, low automation, high energy consumption, significant safety hazards, and excessive non-productive time.
A continuous production method is adopted, in which polymerization reactors are connected in series, and materials flow continuously in the reactors. Steady-state production is achieved through multi-stage polymerization reactors and modification regulating reactors. Combined with a DCS control system, automated management is carried out to reduce human intervention.
It has achieved efficient and stable production of VAE emulsions, with uniform product quality, reduced energy consumption and safety hazards, improved production efficiency and automation, and reduced non-productive time and labor costs.
Abstract
Description
Technical Field
[0001] This invention relates to the field of VAE emulsion preparation technology, and in particular to a method for continuous production of VAE emulsions. Background Technology
[0002] Currently, the vast majority of VAE emulsion production plants worldwide employ batch or semi-batch processes. This means that raw materials are added to a single reactor, either all at once or in stages, and the entire polymerization reaction is completed under set conditions. After the reaction, the entire batch of material is discharged for further processing (such as blending, filtration, and packaging), and then the reactor is cleaned in preparation for the next batch of production.
[0003] However, this method has low production efficiency, with a significant amount of non-productive time (feeding, heating, cleaning, etc.); product quality consistency may vary between batches, requiring strict quality control to ensure consistency; and operating costs are high due to the low level of automation and potentially high energy consumption caused by frequent heating and cooling. Regarding safety, each batch operation requires manual intervention, posing safety hazards and potentially causing errors that could affect the overall response. Summary of the Invention
[0004] To address the above problems, this invention provides a method for continuous production of VAE emulsions, comprising the following steps: 1) Connect the outlets and inlets of polymerization reactors 1, 2 and 3 one after the other in sequence. Connect the outlet of polymerization reactor 3 to the inlet of the next polymerization reactor. Connect the outlet of the next polymerization reactor to the inlet of the modification and conditioning reactor. 2) Ethylene gas is simultaneously introduced into polymerization reactors 1, 2, and 3. Emulsifier, deionized water, and auxiliary agent are injected into polymerization reactor 1. VAc, initiator, and reducing agent are injected into polymerization reactor 2. Initiator and reducing agent are injected into polymerization reactor 3. The temperature is increased to carry out the reaction. 3) Inject reducing agent and oxidizing agent into the post-polymerization reactor, and start degassing to recover the generated gas phase; 4) Inject other additives, emulsifiers and pH adjusters into the modification and conditioning reactor. The outlet of the modification and conditioning reactor is connected to the intermediate tank. The material discharged from the intermediate tank is dehydrated to obtain VAE emulsion.
[0005] The functions of polymerization reactors 1, 2, and 3 are to initiate the polymerization reaction of materials such as ethylene and VAc under suitable temperature, pressure, and with the aid of initiators and reducing agents, laying the foundation for the formation of VAE emulsions. Polymerization reactor 1 serves as the starting point of the reaction. The emulsifier injected into it reduces the surface tension at the oil-water interface, allowing the reactants to disperse better and form an emulsion system. Deionized water provides the reaction medium, and a 3.5% acetic acid solution helps regulate the reaction environment, creating suitable reaction conditions to promote the effective progress of subsequent reactions. In polymerization reactor 1, at 30℃ and 3.5MPa, the materials are initially mixed and begin a slow reaction. In polymerization reactor 2, by injecting VAc, 1% sodium persulfate initiator, and 0.5% sodium formaldehyde sulfoxylate solution as a reducing agent, at 60℃ and 3.5MPa, the initiator decomposes to generate free radicals, initiating the polymerization reaction between VAc and ethylene, further intensifying the polymerization reaction and significantly increasing the degree of polymerization of the materials. Polymerization reactor 3 is also injected with 1% sodium persulfate initiator and 0.5% sodium formaldehyde sulfoxylate solution as a reducing agent. Under conditions of 50℃ and 1.6MPa, the reaction is further controlled and refined to ensure a more complete and stable polymerization reaction, guaranteeing the formation of a polymer product with specific properties. These three polymerization reactors are connected sequentially, allowing for continuous material flow and reaction. This achieves continuity and stability in the reaction process, providing a solid foundation for subsequent polymerization reactors and modification regulating reactors. This ensures that the entire continuous production process can efficiently and stably produce VAE emulsions of uniform quality.
[0006] After polymerization in the first three polymerization reactors, the post-polymerization reactor serves to further react and refine the polymerization product. Injecting a 10% solution of sodium formaldehyde sulfoxylate (a reducing agent) and a 10% solution of tert-butyl hydrogen peroxide (an oxidizing agent) at 70°C and 0 Pa promotes the continued polymerization of unreacted monomers, increasing monomer conversion and reducing residual monomer content. Simultaneously, initiating a degassing operation effectively removes bubbles generated during the reaction, preventing them from negatively impacting product quality, such as affecting emulsion stability and appearance. The generated gas phase is recovered, which not only reduces production costs and raw material waste but also prevents gaseous substances from polluting the environment, aligning with the principles of green production.
[0007] After processing in the post-polymerization reactor, the material enters the modification and conditioning reactor. In the modification and conditioning reactor, 15% calcium formate solution and other additives, 18% polyvinyl alcohol solution as an emulsifier, and 10% sodium hydroxide solution as a pH adjuster are injected. Under conditions of 70℃, the other additives can improve certain properties of the VAE emulsion, such as increasing its adhesion and water resistance; the emulsifier can further stabilize the emulsion system and prevent emulsion separation or demulsification; the pH adjuster is used to adjust the pH of the emulsion to a suitable value, ensuring the stability and performance of the emulsion. The outlet of the modification and conditioning reactor is connected to an intermediate tank, which acts as a buffer and storage tank, ensuring the material is in a relatively stable state before entering the dehydration process. The material discharged from the intermediate tank enters the dehydration process to obtain the VAE emulsion. The dehydration process removes excess water from the emulsion, increasing its solids content to meet the needs of different users.
[0008] Compared to existing batch or semi-batch processes, the continuous VAE emulsion production method of this invention offers significant advantages. The entire production process operates uninterruptedly for extended periods under steady-state conditions, avoiding the substantial non-productive time required for feeding, heating, and cleaning in batch processes. This results in high output per unit time and high production efficiency. Because the system is in a steady state, the reaction conditions in each reactor are relatively stable, leading to uniform product quality and minimal variation between batches, reducing the cost and difficulty of strict quality control. Furthermore, this method is highly automated, minimizing human intervention and reducing the impact of safety hazards and operational errors on the reaction. Overall energy consumption is also reduced by avoiding frequent heating and cooling, resulting in significant improvements in production efficiency, product quality, operating costs, and safety.
[0009] To ensure the stable implementation of the method of the present invention, the entire process includes five units: raw materials, batching, polymerization, degassing, and packaging.
[0010] a) Raw Material Unit: Liquid ethylene is unloaded from purchased tank trucks into an ethylene storage tank, then pressurized by a cryogenic pump and evaporated into gaseous ethylene via an ethylene evaporator, which is then stored in a high-pressure ethylene storage tank for later use. When ethylene is needed during production, it enters the reactor from the high-pressure ethylene storage tank at a controlled pressure via a pipeline pressure regulating valve. Purchased vinyl acetate (VAc) is stored in a vinyl acetate storage tank. During production, VAc is pumped and metered before being continuously fed into the reactor.
[0011] b) Batching unit: Based on the required additives, multiple mixing tanks with stirring and weighing functions are needed. According to the formula requirements, the corresponding aqueous solutions of emulsifiers, surfactants, initiators, pH adjusters, and modifiers are prepared. The prepared solutions that meet the requirements are transferred to their respective metering tanks. During production, according to the process batching requirements, they are continuously added to the system through metering pumps and flow meters.
[0012] c) Polymerization Unit: This is a five-stage series reactor. The prepared emulsifier system, dispersant, pure water, and auxiliary agents are metered into polymerization reactor P1. Once a certain liquid level is reached, the reactor agitator is turned on, and ethylene is introduced into the reactor. When the set pressure is reached, the ethylene valve is automatically closed, and the reactor's self-controlled transfer valve is opened to transfer material to polymerization reactor P2 (automatically metered transfer amount). The PI reactor is continuously fed according to the set ratio. After reactor P2 reaches a certain liquid level, the corresponding VAc monomer is metered in, agitation is started, and the temperature is increased. Simultaneously, ethylene gas and initiator are introduced (the feed is continuously metered according to the set values), and the polymerization reaction begins. When the temperature, pressure, and liquid level of polymerization reactor P2 reach the set values (reactor temperature and pressure are automatically regulated), samples are taken for analysis. Once the reaction indicators reach the set targets, the transfer valve is opened to transfer material to the next stage reactor P3 (automatically metered transfer amount). Once reactor P3 reaches a certain liquid level, the agitator is activated, and ethylene gas and initiator are simultaneously introduced (continuously added according to set values). When the temperature, pressure, and liquid level of reactor P3 reach the set values (reactor temperature and pressure are automatically regulated), samples are taken for analysis. After the reaction indicators reach the set targets, the transfer valve is opened to transfer material to the next stage reactor P4. The first three reactors operate under pressure (pressure is automatically controlled according to set values), while reactor P4 is an atmospheric pressure reactor. Once reactor P4 reaches a certain liquid level, the agitator is activated, and initiator and additives are continuously added (continuously added according to set values). Reactor P4 contains the post-polymerization reaction material and operates at atmospheric pressure. The material entering reactor P4 undergoes reduced pressure flash evaporation, and the gas phase is condensed to a vapor-liquid separator. The small amount of entrained liquid is separated and returned to reactor P4 for reuse. The separated tail gas contains more than 92% ethylene and a small amount of VAC and water, which is sent to the tail gas recovery system to recover the ethylene (the ethylene is pressurized by a compressor, purified by a condenser, and then recycled back to the reactor feed system to reduce unit consumption). Once the liquid level in reactor P4 reaches the set value, a sample is taken for analysis. If the sample passes the analysis, the reactants are transferred to the degassing and regulating unit. The post-polymerization reactor is configured with two or more reactors, allowing for easy switching and control of the polymerization endpoint, thus ensuring stable product quality.
[0013] d) Degassing Unit: After the reaction, the VAE emulsion is sent to the P5 reactor (degassing and conditioning reactor). pH adjusters and other conditioning aids are continuously metered into the reactor. The reactor temperature is automatically controlled. Degassing is performed using vacuum degassing. After a certain time, material samples are taken for analysis. If the samples pass the analysis, the emulsion is sent to a buffer tank, and then filtered before being sent to the finished product tank. Residual ethylene from degassing is sent to the tail gas treatment system. The degassing and conditioning reactor can be configured with two or more reactors for switching purposes.
[0014] e) Packaging Unit: The finished emulsion product in the finished product tank is pumped to the automatic filling station for barrel filling or sent to the spray drying device to dry into powder for bagging as needed.
[0015] This invention involves the continuous flow of materials in reactors connected in series. Raw materials continuously enter from one end of the reactor, while reaction products continuously flow out from the other end into the next reactor. The entire process operates uninterruptedly for extended periods under steady-state conditions, resulting in high output and efficiency per unit time. The system remains in a steady state, ensuring consistent product quality. This invention employs an advanced DCS control system for process control, reducing human intervention, enhancing safety, increasing automation, lowering labor costs, and reducing energy consumption per unit product. Detailed Implementation
[0016] The present invention will be described below with reference to examples. These examples are only used to explain the present invention and are not intended to limit the scope of the present invention.
[0017] Example 1 A method for continuous production of VAE emulsion includes the following steps: 1. Preparation: Inspect the raw material unit to ensure that liquid ethylene has been unloaded from the purchased tank trucks into the ethylene storage tank, pressurized by a cryogenic pump, evaporated into gaseous ethylene by an ethylene evaporator, and then stably stored in the high-pressure ethylene storage tank; the purchased vinyl acetate (VAc) has also been properly stored in the vinyl acetate storage tank. Simultaneously, in the batching unit, multiple mixing kettles equipped with stirring and weighing functions have precisely prepared the corresponding aqueous solutions of emulsifiers, surfactants, initiators, pH adjusters, and modifiers according to the formula requirements, and transferred them to their respective metering tanks. Specifically, the emulsifier is an 18% polyvinyl alcohol solution, the surfactant is a suitable anionic surfactant, the initiator is a 1% sodium persulfate solution, the pH adjuster is a 10% sodium hydroxide solution, and the modifier is a 15% calcium formate solution. These solutions are waiting in the metering tanks, ready to be continuously added to the system via metering pumps and flow meters according to the process batching requirements.
[0018] 2. Polymerization Reaction: The prepared emulsifier system, dispersant, pure water, and auxiliary agents are metered and added to polymerization reactor P1. When polymerization reactor P1 reaches a certain liquid level, the reactor agitator is turned on, and then ethylene is introduced into the reactor. When the set pressure is reached, the ethylene valve is automatically closed, and the reactor's automatic transfer valve is opened, transferring material to polymerization reactor P2 according to the automatically controlled metered transfer rate. At the same time, polymerization reactor P1 is continuously fed according to the set ratio.
[0019] Once the polymerization reactor P2 reaches a certain liquid level, the corresponding VAc monomer is metered in, stirring is started and the temperature is raised. Simultaneously, ethylene gas and initiator are continuously introduced according to the set values to begin the polymerization reaction. When the temperature, pressure, and liquid level of the polymerization reactor P2 reach the set values (the reactor temperature and pressure are automatically regulated), samples are taken for analysis. When the reaction indicators reach the set targets, the transfer valve is opened, and the material is transferred to the next stage reactor P3 according to the automatically controlled metered transfer rate.
[0020] Once the polymerization reactor P3 reaches a certain liquid level, the agitator is activated, and ethylene gas and initiator are continuously introduced according to the set values. When the temperature, pressure, and liquid level of the polymerization reactor P3 reach the set values (the reactor temperature and pressure are automatically regulated), samples are taken for analysis. After the reaction indicators reach the set targets, the transfer valve is opened to transfer the material to the next stage reactor P4. The first three reactors operate under pressure, and the pressure is automatically controlled according to the set values.
[0021] Once the polymerization reactor P4 reaches a certain liquid level, the agitator is activated, and initiator and additives are continuously added according to the set values. The polymerization reactor P4 is an atmospheric pressure reactor. The material entering P4 undergoes vacuum flash evaporation, and the vapor phase is condensed into a vapor-liquid separator. The small amount of entrained liquid is separated and returned to P4 for reuse. The separated tail gas contains over 92% ethylene and small amounts of VAC and water. This is sent to the tail gas recovery system to recover the ethylene. The ethylene is then pressurized by a compressor, purified by a condenser, and recycled back to the reactor feed system to reduce unit consumption. When the liquid level in the polymerization reactor P4 reaches the set value, a sample is taken for analysis. If it passes the test, the reactants are transferred to the degassing and regulating unit.
[0022] 3. Degassing Treatment: After the reaction, the VAE emulsion is sent to the P5 reactor (degassing and conditioning reactor). pH adjusters and other conditioning agents are continuously metered into the reactor, and the reactor temperature is automatically regulated. Degassing is performed using vacuum degassing. After a certain time, the material is sampled and analyzed. If it passes the test, the emulsion is sent to a buffer tank, and then filtered before being sent to the finished product tank. Residual ethylene from degassing is sent to the tail gas treatment system. The degassing and conditioning reactor can be set up with two or more reactors for switching purposes.
[0023] 4. Packaging: The finished emulsion product in the finished product tank is pumped to an automatic filling station for drum filling as needed, or sent to a spray drying device to dry into powder for bagging.
[0024] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for continuous production of VAE emulsion, characterized in that, Includes the following steps: 1) Connect the outlets and inlets of polymerization reactors 1, 2 and 3 one after the other in sequence. Connect the outlet of polymerization reactor 3 to the inlet of the next polymerization reactor. Connect the outlet of the next polymerization reactor to the inlet of the modification and conditioning reactor. 2) Ethylene gas is simultaneously introduced into polymerization reactors 1, 2, and 3. Emulsifier, deionized water, and auxiliary agent are injected into polymerization reactor 1. VAc, initiator, and reducing agent are injected into polymerization reactor 2. Initiator and reducing agent are injected into polymerization reactor 3. The temperature is increased to carry out the reaction. 3) Inject reducing agent and oxidizing agent into the post-polymerization reactor, and start degassing to recover the generated gas phase; 4) Inject other additives, emulsifiers and pH adjusters into the modification and conditioning reactor. The outlet of the modification and conditioning reactor is connected to the intermediate tank. The material discharged from the intermediate tank is dehydrated to obtain VAE emulsion.
2. The method for continuous production of VAE emulsion according to claim 1, characterized in that, The auxiliary agent in the polymerization reactor 1 is a 3.5% acetic acid solution, and the emulsifier is an 18% polyvinyl alcohol solution.
3. The method for continuous production of VAE emulsion according to claim 1, characterized in that, In the polymerization reactor 2, the initiator is 1% sodium persulfate and the reducing agent is 0.5% sodium formaldehyde sulfoxylate solution.
4. The method for continuous production of VAE emulsion according to claim 1, characterized in that, In the polymerization reactor 3, the initiator is 1% sodium persulfate and the reducing agent is 0.5% sodium formaldehyde sulfoxylate solution.
5. The method for continuous production of VAE emulsion according to claim 1, characterized in that, In the post-polymerization reactor, the reducing agent is a 10% solution of sodium formaldehyde sulfoxylate, and the oxidizing agent is a 10% solution of tert-butyl hydrogen peroxide.
6. The method for continuous production of VAE emulsion according to claim 1, characterized in that, In the modified regulating vessel, other additives include a 15% calcium formate solution, an 18% polyvinyl alcohol solution as emulsifier, and a 10% sodium hydroxide solution as pH adjuster.
7. The method for continuous production of VAE emulsion according to claim 1, characterized in that, The temperature of polymerization reactor 1 is 30℃ and the pressure is 3.5MPa; the temperature of polymerization reactor 2 is 60℃ and the pressure is 3.5MPa; the temperature of polymerization reactor 3 is 50℃ and the pressure is 1.6MPa; the temperature of post-polymerization reactor is 70℃ and the pressure is 0Pa; the temperature of modification regulating reactor is 70℃.