Polymerization reaction system and use thereof

Abstract

The present application relates to the field of polymerization equipment and preparation of ethylene modified polyvinyl alcohol, and in particular to a polymerization reaction system and application thereof. The polymerization reaction system comprises an oxygen removal device (A) and a reaction device (B) connected in sequence; the oxygen removal device (A) comprises an oxygen remover tank body (1), a liquid monomer feeding port (2) and a bubbling gas feeding port (3) arranged at the top of the oxygen remover tank body (1); the reaction device (B) comprises a reactor tank body (8), a deoxygenated liquid monomer feeding port (9) and a gas phase monomer feeding port (12) arranged at the top of the reactor tank body (8), and a heat exchange coil (13) arranged in the reactor tank body (8). The system has excellent heat removal effect, low leakage risk and high safety.

Description

Technical Field

[0001] This invention relates to the field of polymerization equipment and the preparation of ethylene-modified polyvinyl alcohol, specifically to polymerization reaction systems and their applications. Background Technology

[0002] Ethylene-modified polyvinyl alcohol (PVA) is a modified PVA product obtained by alcoholysis of ethylene-vinyl acetate copolymer. The ethylene-vinyl acetate copolymer is obtained by copolymerizing ethylene and vinyl acetate in solution. This copolymerization reaction is exothermic, and to ensure its smooth progress, the heat generated during the reaction needs to be removed promptly. Because ethylene participates in the reaction, the raw material solvent and vinyl acetate cannot reach an azeotropic state, and conventional external heat removal methods cannot meet the heat removal requirements.

[0003] CN115991810A discloses a method for preparing EPVA under low-pressure conditions, including a polymerization reaction step: a copolymer system undergoes polymerization in a reaction environment to obtain a copolymer resin; the raw materials of the copolymer system include ethylene, vinyl ester compounds, solvent, and initiator; the copolymer system includes a polymerization liquid and a gas phase consisting of ethylene, vaporized vinyl ester compounds, and vaporized solvent; during the polymerization reaction, the gas phase is discharged from the reaction environment and flows in parallel with the liquid phase consisting of vinyl ester compounds and solvent, and then after cooling, a condensate and a non-condensable gas are formed; the condensate is transported back to the reaction environment, and the non-condensable gas is pressurized and then transported back to the reaction environment; and the polymerization liquid containing the copolymer resin is continuously collected from the reaction environment.

[0004] CN115991803A discloses a method for preparing ethylene-modified polyvinyl alcohol based on external circulation, including a polymerization reaction step: a copolymer system undergoes polymerization in a reaction environment to obtain a copolymer resin; the raw materials of the copolymer system include ethylene, ethylene ester compounds and an initiator; the copolymer system includes a polymerization liquid, which flows out from the reaction environment during the polymerization reaction and is returned to the reaction environment after cooling.

[0005] The above methods all involve removing the reactants from the reaction system and exchanging heat externally, which requires additional reaction system conveying devices, resulting in complex equipment and posing a safety risk of leakage.

[0006] There is an urgent need to develop a polymerization reaction system that can efficiently and safely remove heat from the reaction in order to achieve the safe preparation of ethylene-modified polyvinyl alcohol. Summary of the Invention

[0007] This invention addresses the problems of complex heat removal equipment for polymerization reactions, easy leakage at equipment connections, and high safety risks in the preparation of ethylene-modified polyvinyl alcohol, by providing a polymerization reaction system and its application.

[0008] To achieve the above objectives, a first aspect of the present invention provides a polymerization reaction system, the polymerization reaction system comprising a deoxygenation device A and a reaction device B connected in sequence;

[0009] The deoxygenation device A includes a deoxygenator tank 1, and a liquid phase monomer inlet 2 and a bubbling gas inlet 3 located on the top of the deoxygenator tank 1.

[0010] The reaction device B includes a reactor tank 8, a deoxygenated liquid phase monomer inlet 9 and a gas phase monomer inlet 12 located at the top of the reactor tank 8, and a heat exchange coil 13 located inside the reactor tank 8.

[0011] The second aspect of this invention provides the application of the polymerization reaction system described in the first aspect in the preparation of ethylene-modified polyvinyl alcohol.

[0012] The polymerization reaction system provided by this invention includes a deoxygenation device and a reaction device. The reaction device employs a built-in heat removal unit, resulting in a relatively simple system composition with excellent heat removal performance, low leakage risk, and high safety. This system is particularly suitable for the polymerization reaction of ethylene monomers and ethylene ester monomers in the preparation of ethylene-modified polyvinyl alcohol. Attached Figure Description

[0013] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0014] Figure 1 This is a schematic diagram of a polymerization reaction system according to one embodiment of the present invention.

[0015] Explanation of reference numerals in the attached figures

[0016] A-Deoxygenation device B-Reaction device 1-Deoxygenator tank

[0017] 2-Liquid phase monomer inlet; 3-Blowing gas inlet; 4-Blower.

[0018] 5-Deaerator agitator; 6-Condenser; 7-Deaeratored liquid monomer discharge port. 8-Reactor tank; 9-Deoxygenated liquid monomer inlet; 10-Solvent inlet

[0019] 11-Initiator inlet; 12-Gas phase monomer inlet; 13-Heat exchange coil

[0020] 13-1-Cooling medium inlet 13-2-Cooling medium outlet 14-Reaction stirrer

[0021] 15-Temperature detector 16-Pressure detector 17-Explosion-proof disc

[0022] 18-Polymerization product outlet Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0025] The first aspect of this invention provides a polymerization reaction system, such as Figure 1 As shown, the polymerization reaction system includes a deoxygenation device A and a reaction device B connected in sequence.

[0026] The deoxygenation device A includes a deoxygenator tank 1, and a liquid phase monomer inlet 2 and a bubbling gas inlet 3 located on the top of the deoxygenator tank 1.

[0027] The reaction device B includes a reactor tank 8, a deoxygenated liquid phase monomer inlet 9 and a gas phase monomer inlet 12 located at the top of the reactor tank 8, and a heat exchange coil 13 located inside the reactor tank 8.

[0028] According to the present invention, in the polymerization reaction system, the deoxygenation device A is used to deoxygenate the liquid monomer using bubbling gas to obtain deoxygenated liquid monomer. The deoxygenation device A can reduce or remove oxygen in the liquid monomer, thereby facilitating the efficient and smooth progress of subsequent polymerization reactions.

[0029] According to the present invention, in the polymerization reaction system, in the deoxygenation device A, both the liquid monomer inlet 2 and the bubbling gas inlet 3 can be connected to the outside via corresponding pipelines. For example, the liquid monomer inlet 2 can be connected to a liquid monomer storage tank via a liquid monomer inlet pipe. Figure 1 (Not shown in the image); the bubbling gas inlet 3 can be connected to the bubbling gas storage tank via the bubbling gas inlet pipe. Figure 1 (Not shown in the image).

[0030] According to the present invention, in the polymerization reaction system, in the deoxygenation device A, preferably, a bubbler 4 is provided inside the deoxygenator tank 1, and the bubbler 4 is connected to the bubbling gas inlet 3. The bubbling gas enters the bubbler 4 through the bubbling gas inlet 3, and a large number of bubbles are generated by the bubbler 4, so as to better perform the functions of bubbling and deoxygenation.

[0031] In this invention, the definition of the bubbler 4 is relatively broad, and any bubbler device can be used, but a ring-shaped bubbler is preferred.

[0032] According to the present invention, in the polymerization reaction system, in the deoxygenation device A, preferably, the deoxygenator tank 1 is provided with a deoxygenation agitator 5, which is used to bubble under stirring conditions to obtain a better deoxygenation effect.

[0033] According to the present invention, in the polymerization reaction system, in the deoxygenation device A, preferably, a condenser 6 is connected to the top of the deoxygenator tank 1. The condenser 6 is used to condense the bubbling gas that rises to the top of the deoxygenator tank 1 after the deoxygenation treatment, and to incorporate the condensed product into the deoxygenated liquid monomer.

[0034] According to the present invention, preferably, the condenser 6 is disposed on the top of the deaerator tank 1 and located outside the deaerator tank 1.

[0035] In this invention, the definition of the condenser 6 is relatively broad, and any condensation device capable of condensing gaseous substances to obtain liquid-phase condensation products can be used.

[0036] According to the present invention, in the polymerization reaction system, in the deoxygenation device A, the bottom of the deoxygenator tank 1 is provided with a deoxygenated liquid monomer outlet 7.

[0037] According to the present invention, in the deoxygenation device A, liquid monomer (e.g., ethylene ester monomer) enters the deoxygenator tank 1 through the liquid monomer inlet 2. The deoxygenation agitator 5 is turned on, and under agitation conditions, bubbling gas (e.g., nitrogen) enters the bubbler 4 through the bubbling gas inlet 3. A large number of bubbles are generated by the bubbler 4, and oxygen is removed from the liquid monomer by bubbling action to obtain deoxygenated liquid monomer. Then, the bubbling gas (carrying some liquid monomer) rises to the upper part of the deoxygenator tank 1 and enters the condenser 6. Through condensation, the liquid monomer carried in the bubbling gas is cooled and condensed into a liquid stream, which returns to the deoxygenator tank 1 and is incorporated into the deoxygenated liquid monomer. The deoxygenated liquid monomer leaves the deoxygenation device A through the liquid monomer outlet 7 at the bottom of the deoxygenator tank 1.

[0038] According to the present invention, in the polymerization reaction system, the reaction device B is used to polymerize the deoxygenated liquid-phase monomer and the gaseous monomer (e.g., ethylene) to obtain the polymerization product. A large amount of heat is released during the polymerization reaction, and it is necessary to remove the heat generated during the polymerization process in a timely manner.

[0039] According to the present invention, in the polymerization reaction system, preferably, the reactor tank 8 is provided with a jacket on its exterior. The jacket is used to heat the reactor tank 8.

[0040] According to the present invention, in the polymerization reaction system, the jacket of the reactor tank 8 is relatively wide, and a conventional reactor jacket structure can be adopted. Heat can be provided for the start-up of the polymerization reaction by circulating hot oil, hot water, or hot steam in the jacket, while simultaneously providing thermal insulation for the polymerization process.

[0041] According to the present invention, in the polymerization reaction system, the deoxygenated liquid monomer inlet 9 of the reaction device B is connected to the deoxygenated liquid monomer outlet 7 of the deoxygenation device A.

[0042] According to the present invention, in the polymerization reaction system, the top of the reactor tank 8 in the reaction device B is further provided with a solvent inlet 10 and an initiator inlet 11.

[0043] According to the present invention, both the solvent inlet 10 and the initiator inlet 11 can be connected to the outside via corresponding pipelines. For example, the solvent inlet 10 can be connected to a solvent storage tank via a solvent inlet pipe. Figure 1 (Not shown in the image); the initiator inlet 11 can be connected to the initiator storage tank via an initiator inlet pipe. Figure 1 (Not shown in the image).

[0044] According to the present invention, in the polymerization reaction system, in the reaction device B, a gas phase monomer feed valve is provided at the gas phase monomer feed inlet 12. Figure 1 (Not shown in the diagram). The feed rate of the gaseous monomer and the reaction pressure inside the reactor tank 8 are adjusted by controlling the opening of the gaseous monomer feed valve.

[0045] According to the present invention, in the polymerization reaction system, in the reaction device B, the bottom of the reactor tank 8 is provided with a polymerization product outlet 18 for discharging the polymerization product outside the polymerization reaction system.

[0046] In this invention, the heat exchange coil 13 is subject to a wide range of restrictions, and any conventional heat exchange coil can be used. An immersion coil heat exchange coil is preferred, which is beneficial for obtaining better heat removal effect, has a simple structure, high safety, and low leakage risk.

[0047] According to the present invention, preferably, the cooling medium inlet 13-1 and the cooling medium outlet 13-2 of the heat exchange coil 13 are both located at the top of the deaerator tank 1.

[0048] According to the present invention, preferably, a cooling medium inlet valve is provided at the cooling medium inlet 13-1. The flow rate of the cooling medium is adjusted by controlling the opening degree of the cooling medium inlet valve, thereby adjusting the heat dissipation process and the heat in the reaction system.

[0049] According to the present invention, in the polymerization reaction system, in the reaction device B, a reaction stirrer 14 is provided inside the reactor tank 8.

[0050] According to the present invention, in the polymerization reaction system, preferably, the reactor tank 8 is provided with a temperature detector 15 for monitoring temperature changes during the polymerization reaction.

[0051] In this invention, the temperature detector 15 is broadly defined and can be any conventional temperature detector, such as a thermometer.

[0052] According to the present invention, preferably, the temperature detector 15 is connected to the cooling medium feed valve through a temperature regulating valve, so as to automatically control the opening of the cooling medium feed valve according to the temperature change during the polymerization reaction, thereby controlling the temperature of the reaction system.

[0053] According to the present invention, in the polymerization reaction system, preferably, a pressure detector 16 and an explosion-proof plate 17 are provided on the top of the reactor tank 8 in the reaction device B.

[0054] In this invention, the definition of the pressure detector 16 is broad, and any conventional pressure detector, such as a pressure gauge, can be used.

[0055] According to the present invention, preferably, the pressure detector 16 is connected to the gas phase monomer feed valve through a solenoid valve, so that when the pressure of the reaction system (reaction pressure) is lower than the set pressure value, the opening of the gas phase monomer feed valve is automatically increased, and vice versa.

[0056] According to the present invention, in the polymerization reaction system, in the reaction device B, the explosion-proof plate 17 is used to release pressure when the reaction pressure exceeds the limit, thereby ensuring equipment safety.

[0057] According to the present invention, the material of the cooling medium used in the heat exchange coil 13 is broadly defined, for example, water, reaction solvent (i.e., the solvent used in the polymerization reaction), or liquid monomer (i.e., the raw material liquid monomer used in the polymerization reaction) can be used. Preferably, the liquid monomer can be used as the cooling medium, and through heat exchange, the reaction system can be cooled down while the raw material liquid monomer is preheated.

[0058] According to the present invention, in the polymerization reaction system, the cooling medium inlet 13-1 is optionally connected to the deaerator tank 1, and when the cooling medium inlet 13-1 is connected to the deaerator tank 1, the cooling medium outlet 13-2 is connected to the deoxygenated liquid monomer inlet 9. By adopting this connection method, a portion of the deoxygenated liquid monomer can be used as the cooling medium.

[0059] In this invention, the cooling medium inlet 13-1 is connected to the deaerator tank 1. Specifically, it is preferable to connect the cooling medium inlet 13-1 to the liquid phase monomer outlet 7 of the deaerator tank 1.

[0060] According to the present invention, in the reaction apparatus B, the deoxygenated liquid monomer, gaseous monomer, solvent, and initiator enter the reactor tank 8 through the deoxygenated liquid monomer inlet 9, gaseous monomer inlet 12, solvent inlet 10, and initiator inlet 11, respectively. The reaction stirrer 14 is turned on to uniformly mix the above raw materials to obtain a reaction system. Then, a polymerization reaction is carried out at a certain reaction temperature. During the reaction, when the temperature of the reaction system is higher than the set reaction temperature, the cooling medium inlet valve in the heat exchange coil 13 is automatically opened. The cooling medium carries away the heat in the reaction system through the heat exchange coil 13. After heat exchange, the temperature of the reaction system decreases. When the temperature of the reaction system is lower than the set temperature, the cooling medium inlet valve in the heat exchange coil 13 is automatically closed. The heat of the reaction system is maintained, and the reaction continues, realizing continuous feeding and continuous polymerization. The polymerization product (polymer liquid) leaves the reaction apparatus B through the polymerization product outlet 18 at the bottom of the reactor tank 8.

[0061] The polymerization reaction system provided by this invention has the advantages of simple structure, high safety, and good heat removal effect, which is more conducive to the smooth progress of the polymerization reaction and improves the stability of the reaction process. This system is particularly suitable for the polymerization reaction of ethylene monomers and ethylene ester monomers in the preparation of ethylene-modified polyvinyl alcohol, ensuring stable reaction and consistent raw material conversion.

[0062] The second aspect of this invention provides the application of the polymerization reaction system described in the first aspect in the preparation of ethylene-modified polyvinyl alcohol.

[0063] The preparation steps for ethylene-modified polyvinyl alcohol mainly include polymerization (polymerization of ethylene monomers and ethylene ester monomers), alcoholysis, and product separation. The application described in this invention includes carrying out the polymerization reaction of ethylene monomers and ethylene ester monomers in the polymerization reaction system described in the first aspect above.

[0064] According to the present invention, in the said application, the vinyl ester monomer may be selected from at least one of vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, and vinyl lauryl acetate, preferably vinyl acetate.

[0065] According to the present invention, the solvent used in the polymerization reaction is broadly defined and can be selected from conventional polymerization solvents in the art, preferably at least one of methanol, ethanol, propanol and isobutanol, and more preferably methanol.

[0066] According to the present invention, the initiator used in the polymerization reaction is broadly defined and can be a conventional initiator in the art, selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, bis(4-tert-butylcyclohexyl) peroxydicarbonate, tert-pentyl peroxypentanoate, bis(2-ethylhexyl) peroxydicarbonate, bis(3,5,5-trimethylacetyl) peroxydicarbonate, potassium persulfate, ammonium persulfate, sodium bisulfite, and tartaric acid, preferably azobisisobutyronitrile.

[0067] According to the present invention, in the stated application, the amount of raw materials fed into the polymerization reaction can be selected conventionally in the art. Preferably, the weight ratio of the ethylene ester monomer:solvent:initiator is (250-6500):(100-3500):0.1.

[0068] According to the present invention, in the stated application, the polymerization reaction can be carried out under conditions conventional in the art. Preferably, the conditions for the polymerization reaction include: an ethylene pressure of 0.5-15 bar, more preferably 1-12 bar; a polymerization temperature of 40-80°C, more preferably 45-75°C; and a polymerization reaction time of 2-6.5 h, more preferably 2.5-5.5 h.

[0069] In this invention, ethylene pressure refers to the pressure of ethylene in the reaction environment (e.g., a polymerization reactor), which can be read from the pressure gauge of the polymerization reactor.

[0070] According to the present invention, in the aforementioned application, the polymerization reaction system described in the first aspect is used to carry out the polymerization reaction of ethylene monomer and ethylene ester monomer, which enables the heat of reaction generated during the polymerization process of ethylene monomer and ethylene ester monomer to be removed in a timely manner, resulting in low leakage risk, high safety, ensuring the smooth progress of the polymerization reaction, and improving the stability of the reaction process.

[0071] According to the present invention, in the stated application, the product of the polymerization reaction (ethylene-ethylene ester copolymer) is subjected to alcoholysis and product separation to obtain ethylene-modified polyvinyl alcohol. In the present invention, there are no particular limitations on the alcoholysis and product separation; alcoholysis and separation methods known in the art can be used.

[0072] The present invention will be described in detail below through examples. Unless otherwise specified, all materials used are common commercially available products.

[0073] Degree of alcoholysis of polyvinyl alcohol: determined according to the method specified in Appendix D of GB / T 12010.2-2010.

[0074] Viscosity of polyvinyl alcohol aqueous solution: determined according to the method specified in Appendix E of GB / T 12010.2-2010 and using a Brookfield viscometer.

[0075] Degree of polymerization of polyvinyl alcohol: determined according to the method specified in GB / T 12010.5-2010.

[0076] Ethylene content in polyvinyl alcohol: determined by proton nuclear magnetic resonance spectroscopy.

[0077] Example 1

[0078] (1) Polymerization reaction:

[0079] use Figure 1 The system shown undergoes a polymerization reaction. In deoxygenation device A, vinyl acetate enters deoxygenator tank 1 through liquid monomer inlet 2, and deoxygenation agitator 5 is turned on, with the stirring speed controlled at 100 rpm. Nitrogen gas enters annular bubbler 4 through bubbling gas inlet 3, generating a large number of bubbles. The bubbling action removes oxygen from the vinyl acetate, resulting in deoxygenated vinyl acetate. Then, nitrogen gas (carrying some vinyl acetate) rises to the upper part of deoxygenator tank 1 and enters condenser 6. After condensation, the vinyl acetate carried by the nitrogen gas is cooled and condensed into a liquid stream, which returns to deoxygenator tank 1 and is mixed with the deoxygenated vinyl acetate. The liquid then leaves deoxygenation device A through liquid monomer outlet 7 at the bottom of deoxygenator tank 1 and enters reaction device B.

[0080] In reaction apparatus B, deoxygenated vinyl acetate, ethylene, methanol, and azobisisobutyronitrile (AIBN) enter reactor tank 8 through the deoxygenated liquid monomer inlet 9, gaseous monomer inlet 12, solvent inlet 10, and initiator inlet 11, respectively. The weight ratio of deoxygenated vinyl acetate:methanol:AIBN is controlled at 700:300:0.1, and the ethylene pressure (polymerization pressure, i.e., reactor gauge pressure) is 12 bar. (Before the ethylene feedstock is fed, nitrogen is purged twice sequentially in reactor tank 8.) After ethylene is introduced three times for replacement, the reaction stirrer 14 is turned on (stirring speed controlled at 80 rpm) to ensure uniform mixing of the above raw materials to obtain the reaction system. Circulating hot water at 70°C is then introduced into the outer jacket of the reactor tank 8, and the polymerization reaction is carried out at the set reaction temperature (65°C). During the reaction, the reaction is monitored by a temperature detector 15 (connected to the cooling medium feed valve via a temperature control valve) and a pressure detector 16 (connected to the gaseous monomer feed valve via a solenoid valve). In response to temperature and pressure changes during the process, the explosion-proof plate 17 can release pressure when the reaction pressure exceeds the limit, ensuring system safety. During the reaction, when the temperature of the reaction system exceeds 65°C, the cooling medium inlet valve at the cooling medium inlet 13-1 of the heat exchange coil 13 automatically opens, and the cooling medium (secondary demineralized water) flows into the heat exchange coil 13 (immersion coil heat exchange coil) and flows out from the cooling medium outlet 13-2 of the heat exchange coil 13. Through heat exchange, the heat in the reaction system is carried away, and the temperature of the reaction system decreases. When the temperature of the reaction system falls below 65°C, the cooling medium inlet valve automatically closes, and the heat of the reaction system is maintained. When the reaction pressure is below 12 bar, the opening of the gas phase monomer inlet valve automatically increases, and vice versa, the opening of the gas phase monomer inlet valve automatically decreases to maintain the reaction pressure. The reaction continues, and after 5 hours of reaction, the polymerization liquid continuously leaves the reaction device B from the polymerization product outlet 18. By adjusting the outflow rate of the polymerization liquid, the liquid level in the reaction device B is kept constant, and the reaction time is also maintained.

[0081] (2) Alcohololysis and product separation: Unreacted residual monomers were blown out of the polymerization liquid, and methanol was added to adjust the polymer resin concentration to 40% by weight. Then, a sodium hydroxide methanol solution (the methanol and sodium hydroxide were prepared into a sodium hydroxide methanol solution, wherein the molar ratio of sodium hydroxide to the polymer product was 0.03:1) was added for alcohololysis (alcohololysis temperature was 40℃, and alcohololysis time was 1h). Then, acetic acid was added to terminate the reaction. The product was washed with methanol, and then centrifuged and dried (drying temperature was 110℃, and drying time was 3.5h) to obtain a white ethylene-modified polyvinyl alcohol product (denoted as P1).

[0082] The product P1 has a degree of polymerization of 988, a degree of alcoholysis of 98.5 mol%, an ethylene content of 8.5 mol%, and a viscosity of 13.4 mPa·s for a 4% by weight aqueous solution of P1.

[0083] The polymerization and alcoholysis conditions and results in the above preparation process are detailed in Table 1, and the parameters of the ethylene-modified polyvinyl alcohol product are detailed in Table 2.

[0084] Examples 2-5

[0085] The method of Example 1 was followed, except that different raw material feeding ratios and polymerization conditions were used in the polymerization stage, and different alcoholysis conditions were used in the alcoholysis stage. All other steps and conditions were the same as in Example 1, yielding ethylene-modified polyvinyl alcohol products (denoted as P2-P5).

[0086] The polymerization and alcoholysis conditions and results in the above preparation process are detailed in Table 1, and the parameters of the ethylene-modified polyvinyl alcohol product are detailed in Table 2.

[0087] The polymerization conditions and results in the above preparation process are detailed in Table 1, and the product parameters of ethylene-modified polyvinyl alcohol are detailed in Table 2.

[0088] Table 1

[0089]

[0090] Note: In Table 1, for the heat removal effect, if the difference between the measured temperature inside the reaction device and the set exothermic reaction temperature does not exceed ±1.0℃ when the polymerization is carried out continuously for no less than 3 hours, it is considered to be effective heat removal.

[0091] Continued from Table 1

[0092]

[0093] Table 2

[0094]

[0095] As can be seen from the above embodiments, the polymerization reaction system provided by the present invention uses a built-in heat removal unit. In the process of preparing ethylene-modified polyvinyl alcohol, the polymerization reaction of ethylene monomers and ethylene ester monomers is carried out using this system, which can achieve excellent heat removal effect. The system composition is relatively simple, with low leakage risk and high safety.

[0096] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A polymerization reaction system, characterized in that, The polymerization reaction system includes a deoxygenation device (A) and a reaction device (B) connected in sequence; The deoxygenation device (A) includes a deoxygenator tank (1), and a liquid phase monomer inlet (2) and a bubbling gas inlet (3) located on the top of the deoxygenator tank (1). The reaction device (B) includes a reactor tank (8), a deoxygenated liquid phase monomer inlet (9) and a gas phase monomer inlet (12) located at the top of the reactor tank (8), and a heat exchange coil (13) located inside the reactor tank (8).

2. The polymerization reaction system according to claim 1, wherein, In the deoxygenation device (A), a bubbler (4) is provided inside the deoxygenator tank (1), and the bubbler (4) is connected to the bubbling gas inlet (3); And / or, the deaerator tank (1) is equipped with a deaerator agitator (5).

3. The polymerization reaction system according to claim 1 or 2, wherein, In the deoxygenation device (A), the top of the deoxygenator tank (1) is connected to a condenser (6); And / or, the bottom of the deaerator tank (1) is provided with a liquid phase monomer outlet (7) after deoxygenation.

4. The polymerization reaction system according to any one of claims 1-3, wherein, In the reaction device (B), the reactor tank (8) is provided with a jacket on the outside.

5. The polymerization reaction system according to any one of claims 1-4, wherein, In the reaction apparatus (B), the top of the reactor tank (8) is also provided with a solvent inlet (10) and an initiator inlet (11); And / or, the bottom of the reactor tank (8) is provided with a polymerization product outlet (18).

6. The polymerization reaction system according to any one of claims 1-5, wherein, In the reaction device (B), the cooling medium inlet (13-1) and cooling medium outlet (13-2) of the heat exchange coil (13) are located at the top of the deaerator tank (1); Preferably, a cooling medium inlet valve is provided at the cooling medium inlet (13-1); And / or, the reactor tank (8) is equipped with a reaction stirrer (14).

7. The polymerization reaction system according to claim 6, wherein, In the reaction apparatus (B), the reactor tank (8) is equipped with a temperature detector (15); Preferably, the temperature detector (15) is connected to the cooling medium feed valve via a temperature control valve.

8. The polymerization reaction system according to claim 6 or 7, wherein, In the reaction device (B), a pressure detector (16) and an explosion-proof plate (17) are installed on the top of the reactor tank (8); And / or, the cooling medium inlet (13-1) may optionally be connected to the deaerator tank (1), and when the cooling medium inlet (13-1) is connected to the deaerator tank (1), the cooling medium outlet (13-2) is connected to the deoxygenated liquid phase monomer inlet (9).

9. The application of the polymerization reaction system according to any one of claims 1-8 in the preparation of ethylene-modified polyvinyl alcohol.

10. The application according to claim 9, wherein, The application includes performing polymerization reactions of ethylene monomers and ethylene ester monomers in the polymerization reaction system.

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