A process for the preparation of vinyl chloride polymers with the regulation of the polymerization by an organic base compound

Abstract

The application discloses a preparation process of an organic base compound for regulating polymerization of vinyl chloride, and relates to the technical field of chlorinated polyvinyl chloride plastics, and the specific steps of the preparation process are as follows: selecting a regulator, preparing a reaction system, pH regulation in an initiation period, pH regulation in a growth period, pH regulation in a termination period, and post-treatment; the heterocyclic organic base containing a piperazine ring and a hydroxyethyl substituent is selected as a pH regulator, the alkaline regulation characteristics of the piperazine ring and the adsorption performance of the hydroxyethyl substituent are utilized to form a synergistic effect, the heterocyclic organic base molecule forms a stable structure through N atoms on the piperazine ring and the hydroxyethyl substituent, the heterocyclic organic base molecule can not only play a precise pH regulation function in the polymerization system, but also can change the surface charge state of the resin particles through the interaction between the hydroxyethyl substituent and the surface of the resin particles, reduce the interaction force between the particles, avoid the occurrence of particle agglomeration, and guarantee the chemical stability of the polymerization system, so that the smooth progress of the polymerization reaction is provided, and the regularity of the resin particle morphology is ensured.

Description

Technical Field

[0001] This invention relates to the field of chlorinated polyvinyl chloride plastics technology, specifically to a preparation process for regulating the polymerization of vinyl chloride using organic base compounds. Background Technology

[0002] Chlorinated polyvinyl chloride (PVC), as a high-performance synthetic material, has been widely used in construction, chemical, and municipal fields due to its excellent corrosion resistance, high temperature resistance, and mechanical strength. For example, it is used in the manufacture of key components such as pipes, valves, and sheets. Its market demand continues to grow with the advancement of industrial upgrading and infrastructure construction, making it one of the key development directions in the field of polymer materials in recent years. Optimizing and upgrading related preparation processes has important industrial value and practical significance.

[0003] However, in existing vinyl chloride polymerization processes, pH adjustment often uses inorganic bases or conventional organic amines as regulators. Inorganic bases have a delayed response and are difficult to adapt to the dynamic changes in the polymerization process, making precise control impossible. Conventional organic amines lack specific functional groups that interact with resin particles and have limited structural stability. Furthermore, existing technologies do not implement differentiated pH control for the different needs of the polymerization initiation, growth, and termination phases, resulting in unstable initiation efficiency, easy particle agglomeration during the growth phase, and easy resin degradation during the termination phase, affecting the structural integrity and performance of the final product. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a preparation process for regulating vinyl chloride polymerization using organic base compounds. This invention selects a heterocyclic organic base containing a piperazine ring and a hydroxyethyl substituent as a pH adjuster. It utilizes the synergistic effect of the basicity adjustment properties of the piperazine ring and the adsorption properties of the hydroxyethyl substituent. The heterocyclic organic base molecule forms a stable structure with the hydroxyethyl through the N atom on the piperazine ring. In the polymerization system, it can not only play a precise pH adjustment role, but also change the surface charge state of the particles through the interaction between the hydroxyethyl and the surface of the resin particles, reduce the interaction forces between particles, avoid particle agglomeration, and ensure the chemical stability of the polymerization system. This provides a foundation for the smooth progress of the polymerization reaction and ensures the regularity of the resin particle morphology.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a preparation process for regulating the polymerization of vinyl chloride with organic base compounds, the specific steps of which are as follows: Selected pH adjuster: Heterocyclic organic bases containing piperazine rings and hydroxyethyl substituents are selected as pH adjusters; Preparation of the reaction system: Add vinyl chloride monomer, initiator and dispersant to the polymerization reaction equipment, and stir until the components are mixed evenly to form the initial reaction system; pH control during initiation: When the polymerization reaction enters the initiation phase, a low concentration of heterocyclic organic base is added to the initial reaction system to adjust the pH value of the reaction system to the corresponding range, thus obtaining the reaction system for the initiation stage; pH control during the growth phase: When the polymerization reaction enters the growth phase, based on the real-time pH change trend of the reaction system during the initiation phase, heterocyclic organic bases are gradually added to raise the pH of the reaction system to the corresponding range, thus forming the reaction system during the growth phase. pH control during termination and post-treatment: When the polymerization reaction enters the termination phase, the addition state of the heterocyclic organic base is adjusted to bring the pH value of the reaction system in the growth phase back to the corresponding range. After the vinyl chloride polymerization reaction is completed, the reaction products are subjected to conventional post-treatment processes of degassing, separation and drying to obtain chlorinated polyvinyl chloride resin products.

[0006] Furthermore, in the selected regulator, the piperazine ring of the heterocyclic organic base is chemically bonded to the hydroxyethyl substituent through the N atom on the piperazine ring, and the number of hydroxyethyl substituents is 1-2. The heterocyclic organic base needs to be purified, and the purification process includes vacuum distillation and recrystallization. The purity of the purified heterocyclic organic base is controlled to be ≥99.5%, and the content of metal ion impurities is <1ppm. The metal ions include iron ions, calcium ions, and magnesium ions.

[0007] Furthermore, the specific steps for preparing heterocyclic organic bases using the selected regulator are as follows: using piperazine and a hydroxyethylating agent as raw materials, with chloroethanol or bromoethanol as the hydroxyethylating agent, the reaction temperature is controlled at 60-80℃ and the reaction time is 4-6h under the protection of an inert gas atmosphere of nitrogen or argon to carry out a nucleophilic substitution reaction. After the reaction is completed, impurities are removed by vacuum distillation and then further purified by recrystallization to obtain the target heterocyclic organic base.

[0008] Furthermore, in the preparation reaction system, the filling coefficient of vinyl chloride monomer is 0.4-0.6 based on the effective volume of the polymerization reaction equipment, the mass ratio of initiator to vinyl chloride monomer is 0.001-0.005:1, the mass ratio of dispersant to vinyl chloride monomer is 0.002-0.008:1, the stirring speed of the stirring component in the polymerization reaction equipment is 250-400 r / min, and the stirring time is 30-60 min.

[0009] Furthermore, in the preparation reaction system, the initiator is an azo initiator or a peroxide initiator. The azo initiator includes azobisisobutyronitrile and azobisisoheptanenitrile, and the peroxide initiator includes benzoyl peroxide and dilauryl peroxide. The dispersant is one of polyvinyl alcohol, hydroxypropyl methylcellulose, and gelatin.

[0010] Furthermore, in the pH control during the initiation period, the initiation period is defined as the stage from the start of the polymerization reaction until the conversion rate of vinyl chloride monomer in the reaction system reaches 10%-20%, corresponding to a duration of 0.5-2h; the concentration of the heterocyclic organic base is 0.1-0.3g / L, and the addition method is continuous dripping with a dripping rate of 0.5-1.5mL / min.

[0011] Furthermore, in the pH control during the initiation period, the corresponding pH range of the reaction system is 6.0-6.5. During the addition process, an online pH monitor is used to collect the pH data of the reaction system, and the monitoring frequency is once every 8-12 minutes. The dropping rate is finely adjusted according to the pH monitoring data. At the same time, the temperature of the reaction system is maintained at 45-55℃ through the jacket heat exchange components of the polymerization reaction equipment, and the heat exchange medium is hot water or heat transfer oil.

[0012] Furthermore, in the pH control during the growth period, the growth period is defined as the stage from the end of the initiation period until the conversion rate of vinyl chloride monomer in the reaction system reaches 70%-80%, corresponding to a duration of 2-6 hours; the total amount of heterocyclic organic base added is 1.2-1.8 times the amount added during the initiation period, and the initial addition rate is 0.3-0.8 mL / min, dynamically adjusted based on pH monitoring data; the corresponding pH range of the reaction system is 6.8-7.2, while the temperature of the reaction system is maintained at 50-60℃ through the jacketed heat exchange components of the polymerization reaction equipment.

[0013] Furthermore, in the aforementioned pH control and post-treatment during the termination period, the definition of the termination period is the stage from the end of the growth period to the completion of the vinyl chloride polymerization reaction, corresponding to a duration of 6-8 hours; the addition status of the heterocyclic organic base is adjusted by stopping or reducing the addition, with the rate of reduced addition being 10%-30% of the average addition rate during the growth period, and the pH value recovery time is controlled within 1-2 hours, with the corresponding pH value range of the reaction system being 6.2-6.5.

[0014] Furthermore, in the pH adjustment and post-treatment at the termination period, the degassing process is carried out at a temperature of 70-80℃ for 1-2 hours, with the pressure reduced to 0.05-0.1MPa; the centrifugation speed is 3000-5000r / min for 20-40min; and the drying process is carried out under vacuum at a temperature of 80-100℃ for 3-5 hours, resulting in a resin product with a moisture content of <0.5% after drying.

[0015] Compared with existing technologies, this preparation process for regulating vinyl chloride polymerization with an organic base compound has the following advantages: I. This invention selects a heterocyclic organic base containing a piperazine ring and a hydroxyethyl substituent as a pH adjuster. It utilizes the synergistic effect of the basicity adjustment properties of the piperazine ring and the adsorption properties of the hydroxyethyl substituent. The heterocyclic organic base molecule forms a stable structure with the hydroxyethyl through the N atom on the piperazine ring. In the polymerization system, it can not only perform precise pH adjustment but also change the surface charge state of the particles through the interaction between the hydroxyethyl and the resin particle surface, reducing the interparticle forces and preventing particle aggregation. Simultaneously, it ensures the chemical stability of the polymerization system, providing a foundation for the smooth progress of the polymerization reaction and ensuring the regularity of the resin particle morphology.

[0016] II. This invention divides the polymerization process into three stages: initiation, growth, and termination. Differential pH control is implemented for each stage based on its reaction characteristics. During the initiation stage, a heterocyclic organic base is added to provide a suitable acid-base environment for the reaction, ensuring the stability of the initial reaction. During the growth stage, a regulator is gradually added based on the initial system state to maintain the acid-base balance of the reaction process and promote the uniform growth of resin particles. During the termination stage, the pH is adjusted back to create favorable conditions for the reaction to end, inhibiting inappropriate reactions in the resin chain. The control logic of each stage is coherent and synergistic, ensuring that the polymerization reaction remains stable throughout, guaranteeing the structural regularity and performance consistency of the resin product.

[0017] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1 A flowchart illustrating the preparation process of vinyl chloride polymerization using an organic base compound; Figure 2 A framework diagram of a preparation process for the polymerization of vinyl chloride using an organic base compound; Figure 3 This is a framework diagram of pH control and post-treatment during the termination phase in the preparation process of vinyl chloride polymerization using an organic base compound. Detailed Implementation

[0020] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0021] Example 1: In the large-scale production workshop of chlorinated polyvinyl chloride in a large chemical enterprise, the preparation of heterocyclic organic bases was first carried out. A 50L stainless steel synthesis reactor was selected as the preparation equipment. Piperazine and chloroethanol were added to the synthesis reactor, and nitrogen was introduced as a protective gas. The temperature of the synthesis reactor was controlled to 75°C and maintained at this temperature for 5.5 hours to complete the nucleophilic substitution reaction. After the reaction, the vacuum distillation component of the synthesis reactor was turned on to remove low-boiling-point impurities and obtain the reaction solution. The reaction solution was then transferred to a recrystallization tank for purification treatment, and finally a heterocyclic organic base with a purity of 99.8% was obtained: 1-hydroxyethylpiperazine. The piperazine ring of this heterocyclic organic base is chemically bonded to the hydroxyethyl substituent through the N atom. The total content of metal ion impurities such as iron ions, calcium ions, and magnesium ions was detected to be 0.6 ppm.

[0022] A 1000L polymerization reactor was used as the equipment for vinyl chloride polymerization. Vinyl chloride monomer was injected, with a filling factor of 0.55 calculated based on the effective volume of the reactor. Azobisisobutyronitrile (AIBN) was then added as an initiator, with a mass ratio of AIBN to vinyl chloride monomer of 0.004:1. Polyvinyl alcohol (PVA) was then added as a dispersant, with a mass ratio of dispersant to vinyl chloride monomer of 0.007:1. The stirring assembly of the polymerization reactor was started, and the stirring speed was set to 350 rpm for 55 minutes to ensure thorough mixing of the vinyl chloride monomer, initiator, and dispersant, forming a homogeneous and stable initial reaction system. Figure 1 As shown.

[0023] After the polymerization reaction starts and enters the initiation phase, this stage lasts until the conversion rate of vinyl chloride monomer in the reaction system reaches 18%, with an actual duration of 1.8 hours. Heterocyclic organic bases are continuously added to the initial reaction system via a dropping pump at a concentration of 0.25 g / L and a dropping rate of 1.3 mL / min. During the addition process, an online pH monitor collects the pH data of the system every 12 minutes. The control unit fine-tunes the operating parameters of the dropping pump in real time based on the feedback data to stabilize the pH of the reaction system at 6.4. At the same time, heat transfer oil is circulated into the jacket heat exchange components of the polymerization reactor to maintain the temperature of the reaction system at 53°C.

[0024] After the initiation period, the reaction enters the growth period, which lasts until the conversion rate of vinyl chloride monomer in the reaction system reaches 78%, lasting 5 hours. Based on the real-time pH change trend of the reaction system during the initiation period, the replenishment rate of the heterocyclic organic base is adjusted, with the total replenishment amount being 1.7 times the amount added during the initiation period, and the initial replenishment rate set at 0.7 mL / min. Throughout the growth period, the pH of the reaction system is steadily increased to 7.1 through online monitoring and dynamic adjustment. At the same time, the jacketed heat exchange components continue to work to maintain the temperature of the reaction system at 58℃.

[0025] After the growth period, the termination period begins, lasting 2 hours until the vinyl chloride polymerization reaction is complete. The addition of heterocyclic organic base is adjusted to a reduced-feed method, with the rate of reduced-feed being 28% of the average feed rate during the growth period. After 1.8 hours, the pH of the reaction system is precisely adjusted back to 6.5. After the polymerization reaction is complete, the reaction product is transported to a degassing tower, where the temperature is controlled at 78°C for 1.8 hours. During this process, the pressure inside the tower is reduced to 0.09 MPa using a pressure reducing device to remove unreacted vinyl chloride monomer and volatile impurities. After degassing, the product enters a centrifuge, with the centrifuge speed set at 4800 r / min and a separation time of 38 minutes, separating the wet resin product. Finally, the wet resin is sent to a vacuum drying oven and dried at 98°C for 4.5 hours to obtain chlorinated polyvinyl chloride resin product. Testing shows that the moisture content after drying is 0.35%.

[0026] In summary, heterocyclic organic bases containing piperazine rings and hydroxyethyl substituents are prepared by a synthesis reactor. After purification, the purity and impurity content are ensured to meet the requirements. A polymerization reactor is selected to construct the initial reaction system, allowing for thorough mixing of vinyl chloride monomer, initiator, and dispersant. Subsequently, differentiated pH control is implemented according to different stages of the polymerization reaction. The heterocyclic organic base is added during the initiation stage, a regulator is added based on the previous system state during the growth stage, and the pH value is adjusted back during the termination stage. Temperature is maintained and pH is monitored throughout the process. After the reaction is completed, post-processing steps such as degassing, separation, and drying are performed to finally obtain a stable chlorinated polyvinyl chloride resin product. The entire process is coherent and meets the requirements for large-scale production.

[0027] Example 2: In the pilot plant of the Institute of Polymer Materials, heterocyclic organic bases were prepared using a 30L stainless steel synthesis reactor. Piperazine and bromoethanol were added to the reactor in a specific ratio, and argon gas was introduced as a protective gas. The reactor temperature was controlled at 62°C, and the reaction was continued for 4.2 hours to complete the nucleophilic substitution reaction. After the reaction, impurities in the reaction system were first removed by vacuum distillation, and then the purified solution was transferred to a recrystallization device for further processing. Finally, a heterocyclic organic base with a purity of 99.6% was obtained: 1,4-dihydroxyethylpiperazine, which was used as a pH adjuster. Figure 2As shown, this heterocyclic organic base contains two hydroxyethyl substituents, both of which are chemically bonded to the piperazine ring via an N atom. The metal ion impurity content was detected to be 0.5 ppm.

[0028] A 500L polymerization reactor was used for the polymerization of vinyl chloride. Vinyl chloride monomer was added, and the filling factor calculated based on the effective volume of the polymerization reactor was 0.42. Subsequently, dilauryl peroxide was added as an initiator, with a mass ratio of initiator to vinyl chloride monomer of 0.0015:1. Gelatin was then added as a dispersant, with a mass ratio of dispersant to vinyl chloride monomer of 0.003:1. The stirring assembly of the polymerization reactor was started, and the stirring speed was set to 260 r / min. Stirring was continued for 32 minutes to ensure that all components were fully mixed and a homogeneous initial reaction system was formed.

[0029] After the polymerization reaction starts, it enters the initiation phase, which ends when the conversion rate of vinyl chloride monomer in the reaction system reaches 11%, lasting for 1.1 hours. Heterocyclic organic bases are continuously added to the initial reaction system via a dropping assembly at a concentration of 0.12 g / L and a dropping rate of 0.6 mL / min. During the addition process, the pH value of the reaction system is collected every 8 minutes by an online pH monitor, and the dropping rate of the dropping assembly is finely adjusted based on the collected data to stabilize the pH value of the reaction system at 6.1. At the same time, hot water is circulated through the jacket heat exchange assembly of the polymerization reactor to maintain the temperature of the reaction system at 46°C.

[0030] After the initiation phase, the reaction enters the growth phase, which lasts until the vinyl chloride monomer conversion rate in the reaction system reaches 71%, lasting 3.2 hours. Based on the pH data recorded during the initiation phase, heterocyclic organic bases are gradually added, with the total amount added being 1.3 times the amount added during the initiation phase, and the initial addition rate is set to 0.4 mL / min. During the addition process, pH data is read periodically and the addition rate is dynamically adjusted to raise the pH of the reaction system to 6.8. At the same time, hot water is continuously introduced into the jacketed heat exchange components to maintain the temperature of the reaction system at 51°C.

[0031] After the growth period ends, the period ends, such as... Figure 3As shown, this stage lasts for 1.5 hours until the polymerization reaction is complete. The operator adjusts the addition of the heterocyclic organic base to a reduced-feed method, with the reduced-feed rate being 12% of the average feed rate during the growth phase. After 1.1 hours, the pH of the reaction system is adjusted back to 6.2. After the polymerization reaction is complete, the reaction product is transferred to a small degassing device, where the degassing temperature is controlled at 71°C for 1.1 hours, with the pressure reduced to 0.06 MPa during the process. After degassing, the product is sent to a centrifuge at a speed of 3200 r / min for 22 minutes to obtain wet resin. Finally, the wet resin is placed in a vacuum drying oven and dried at 82°C for 3.2 hours to obtain chlorinated polyvinyl chloride resin product. The moisture content of the dried chlorinated polyvinyl chloride resin product is 0.4%.

[0032] In summary, the target heterocyclic organic base was prepared in a synthesis reactor. After purification by vacuum distillation and recrystallization, its structure and purity were ensured to meet the standards. The initial reaction system was formed by mixing vinyl chloride monomer, initiator, and dispersant in a polymerization reactor. The heterocyclic organic base was added, replenished, and its addition status was adjusted according to the characteristics of the initiation, growth, and termination phases. The temperature of the reaction system was kept stable by heat exchange components, and the pH value was dynamically controlled by online monitoring data. After standardized post-processing, qualified chlorinated polyvinyl chloride resin products were obtained.

[0033] Comparative example: The same 1000L polymerization reactor as in Example 1 was used to prepare chlorinated polyvinyl chloride resin. Sodium hydroxide was selected as the pH adjuster. There was no need to prepare a special heterocyclic organic base in advance. Industrial grade sodium hydroxide solid was used directly with a purity of 98.5% and a metal ion impurity content of 5ppm.

[0034] The same amount of vinyl chloride monomer as in Example 1 was injected into the polymerization reactor, with a filling factor of 0.5. Azobisisobutyronitrile was added as an initiator, with a mass ratio of initiator to vinyl chloride monomer of 0.004:1. Polyvinyl alcohol was added as a dispersant, with a mass ratio of dispersant to vinyl chloride monomer of 0.007:1. The stirring assembly was started, and the stirring speed was set to 350 r / min. Stirring was continued for 55 minutes to form a uniform initial reaction system.

[0035] After the polymerization reaction was started, sodium hydroxide aqueous solution was added to the initial reaction system at once to adjust the pH value of the system to 6.5. No differentiated control was performed for the initiation, growth and termination phases. During the reaction, pH data was collected every 12 minutes using an online pH monitor. It was found that the pH value of the reaction system dropped rapidly to 5.8 after 1 hour in the initiation phase, and then continued to fluctuate during the growth phase, rising to a maximum of 7.5 and dropping to a minimum of 6.0, unable to maintain a stable range. At the same time, heat transfer oil was introduced through the jacket heat exchange components of the polymerization reactor to maintain the system temperature at 53-58℃.

[0036] During the reaction, obvious particle agglomeration was observed in the growth stage system, and a large number of blocky polymerization products were attached to the inner wall of the polymerization reactor. The total polymerization reaction time was the same as in Example 1, which was 8.8 hours. After the reaction was completed, degassing, centrifugation and drying were carried out in the same post-processing as in Example 1: degassing temperature 78℃, duration 1.8 hours, pressure reduced to 0.09MPa; centrifugation speed 4800r / min, duration 38 minutes; vacuum drying temperature 98℃, duration 4.5 hours.

[0037] The final chlorinated polyvinyl chloride resin product was in the form of an irregular block and fine powder mixture. The product moisture content was 0.8% after testing. The resin particles were severely agglomerated and the particle size distribution was uneven. In addition, due to the loss of pH control in the final stage, some resin was degraded. The purity of the product was 96.2%, which was lower than the purity level of the product in Example 1.

[0038] In summary, Example 1 uses a heterocyclic organic base containing a piperazine ring and hydroxyethyl substituents as a pH adjuster. Differential pH control is implemented based on the characteristics of each stage of the polymerization reaction, ensuring a stable acid-base environment throughout the reaction process. Combined with standardized post-processing, the resulting chlorinated polyvinyl chloride resin product has a regular morphology, low impurity content, and meets the required moisture content. In contrast, the comparative example uses a traditional inorganic base as a adjuster without staged pH control, leading to drastic pH fluctuations during the reaction, resulting in resin particle agglomeration and degradation. The product purity and moisture content do not meet the requirements. The comparison demonstrates that the preparation process of this invention effectively addresses the shortcomings of existing technologies and improves the production quality and stability of chlorinated polyvinyl chloride resin.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A process for the preparation of an organic base compound to regulate the polymerization of vinyl chloride, characterized in that, The specific steps of this preparation process are as follows: Selected pH adjuster: Heterocyclic organic bases containing piperazine rings and hydroxyethyl substituents are selected as pH adjusters; Preparation of the reaction system: Add vinyl chloride monomer, initiator and dispersant to the polymerization reaction equipment, and stir until the components are mixed evenly to form the initial reaction system; pH control during initiation: When the polymerization reaction enters the initiation phase, a low concentration of heterocyclic organic base is added to the initial reaction system to adjust the pH value of the reaction system to the corresponding range, thus obtaining the reaction system for the initiation stage; pH control during the growth phase: When the polymerization reaction enters the growth phase, based on the real-time pH change trend of the reaction system during the initiation phase, heterocyclic organic bases are gradually added to raise the pH of the reaction system to the corresponding range, thus forming the reaction system during the growth phase. pH control during termination and post-treatment: When the polymerization reaction enters the termination phase, the addition state of the heterocyclic organic base is adjusted to bring the pH value of the reaction system in the growth phase back to the corresponding range. After the vinyl chloride polymerization reaction is completed, the reaction products are subjected to conventional post-treatment processes of degassing, separation and drying to obtain chlorinated polyvinyl chloride resin products.

2. The process for preparing a vinyl chloride polymer by adjusting polymerization of vinyl chloride with an organic base compound according to claim 1, characterized by, In the selected regulator, the piperazine ring of the heterocyclic organic base is chemically bonded to the hydroxyethyl substituent through the N atom on the piperazine ring. The number of hydroxyethyl substituents is 1-2. The heterocyclic organic base needs to be purified. The purification process includes vacuum distillation and recrystallization. The purity of the purified heterocyclic organic base is controlled to be ≥99.5%, and the content of metal ion impurities is <1ppm.

3. The process for preparing a vinyl chloride polymer by adjusting polymerization of vinyl chloride with an organic base compound according to claim 2, characterized by, The specific steps for preparing heterocyclic organic bases using the selected regulator are as follows: using piperazine and a hydroxyethylating agent as raw materials, the hydroxyethylating agent is selected as chloroethanol or bromoethanol, and under the protection of nitrogen or argon inert gas atmosphere, the reaction temperature is controlled at 60-80℃ and the reaction time is 4-6h to carry out nucleophilic substitution reaction. After the reaction is completed, impurities are removed by vacuum distillation and then further purified by recrystallization to obtain the target heterocyclic organic base.

4. The preparation process for regulating vinyl chloride polymerization with an organic base compound according to claim 1, characterized in that, In the preparation reaction system, the filling coefficient of vinyl chloride monomer is 0.4-0.6 based on the effective volume of the polymerization reaction equipment, the mass ratio of initiator to vinyl chloride monomer is 0.001-0.005:1, the mass ratio of dispersant to vinyl chloride monomer is 0.002-0.008:1, the stirring speed of the stirring component in the polymerization reaction equipment is 250-400 r / min, and the stirring time is 30-60 min.

5. The preparation process for regulating vinyl chloride polymerization with an organic base compound according to claim 4, characterized in that, In the preparation reaction system, the initiator is an azo initiator or a peroxide initiator. The azo initiator includes azobisisobutyronitrile and azobisisoheptanenitrile, and the peroxide initiator includes benzoyl peroxide and dilauryl peroxide. The dispersant is one of polyvinyl alcohol, hydroxypropyl methylcellulose, and gelatin.

6. The preparation process for regulating vinyl chloride polymerization with an organic base compound according to claim 1, characterized in that, In the pH control of the initiation period, the initiation period is defined as the stage from the start of the polymerization reaction until the conversion rate of vinyl chloride monomer in the reaction system reaches 10%-20%, which corresponds to a duration of 0.5-2h; the concentration of the heterocyclic organic base is 0.1-0.3g / L, and the addition method is continuous dripping with a dripping rate of 0.5-1.5mL / min.

7. The preparation process for regulating vinyl chloride polymerization with an organic base compound according to claim 1, characterized in that, During the initiation phase pH control, the corresponding pH range of the reaction system is 6.0-6.

5. During the addition process, an online pH monitor is used to collect the pH data of the reaction system. The monitoring frequency is once every 8-12 minutes. The dropping rate is finely adjusted according to the pH monitoring data. At the same time, the temperature of the reaction system is maintained at 45-55℃ through the jacket heat exchange components of the polymerization reaction equipment. The heat exchange medium is hot water or heat transfer oil.

8. The preparation process for regulating vinyl chloride polymerization with an organic base compound according to claim 1, characterized in that, In the pH control during the growth phase, the growth phase is defined as the period from the end of the initiation phase to the point where the vinyl chloride monomer conversion rate in the reaction system reaches 70%-80%, corresponding to a duration of 2-6 hours. The total amount of heterocyclic organic base added is 1.2-1.8 times the amount added during the initiation phase, with an initial addition rate of 0.3-0.8 mL / min, dynamically adjusted based on pH monitoring data. The corresponding pH range of the reaction system is 6.8-7.2, while the reaction system temperature is maintained at 50-60℃ through the jacketed heat exchange components of the polymerization equipment.

9. The preparation process for regulating vinyl chloride polymerization with an organic base compound according to claim 1, characterized in that, In the aforementioned pH control and post-treatment during the termination period, the termination period is defined as the stage from the end of the growth period to the completion of the vinyl chloride polymerization reaction, which corresponds to a duration of 6-8 hours. The addition status of heterocyclic organic base is adjusted by stopping or reducing the addition. When reducing the addition, the rate is 10%-30% of the average addition rate during the growth period. The pH value recovery time is controlled within 1-2 hours, and the corresponding pH value range of the reaction system is 6.2-6.

5.

10. The preparation process for regulating vinyl chloride polymerization with an organic base compound according to claim 1, characterized in that, In the pH adjustment and post-treatment of the termination period, the degassing process is carried out at a temperature of 70-80℃ for 1-2 hours, with the pressure reduced to 0.05-0.1MPa; the centrifugation speed is 3000-5000r / min for 20-40min; the drying is carried out under vacuum at a temperature of 80-100℃ for 3-5 hours, and the moisture content of the resin product after drying is <0.5%.

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