Process for the preparation of halogenated copolymers and applications, systems for the preparation of halogenated copolymers and applications

Abstract

This invention relates to the field of halogenated copolymers, and discloses a method for preparing halogenated copolymers and their applications, as well as a system for preparing halogenated copolymers and their applications. The preparation method includes the following steps: S1, subjecting a copolymer solution, a halogenating reagent, and a halogenation initiator to a halogenation reaction to obtain a halogenated copolymer solution; S2, neutralizing the halogenated copolymer solution in the presence of an alkaline substance to obtain the halogenated copolymer; wherein the halogenation reaction is an N-stage halogenation reaction, and nitrogen gas is introduced in the Nth stage of the halogenation reaction, where N≥2. This preparation method, by introducing nitrogen gas during the halogenation reaction stage, not only suppresses the occurrence of side reactions and reduces the gel content of the product, but also carries away most of the byproduct hydrogen halide, reducing the amount of alkaline substance used in the subsequent neutralization reaction.

Description

Technical Field

[0001] This invention relates to the field of halogenated copolymers, and more specifically, to a method for preparing halogenated copolymers and its application, and a system for preparing halogenated copolymers and its application. Background Technology

[0002] Halogenated isoisobutylene-alkylstyrene copolymers, especially brominated isobutylene-p-methylstyrene copolymers, possess superior overall properties compared to halogenated isobutylene-isoprene rubbers due to their fully saturated molecular backbone, particularly in heat resistance. Furthermore, the presence of highly reactive benzyl halogen functional groups allows for vulcanization and co-vulcanization with a wider range of rubbers, and also offers greater modification potential. This product, when blended with nylon to create dynamic vulcanization alloys for producing the airtight layer of tires, can be made both lightweight and thin.

[0003] The halogenation reaction of isomonoolefin-alkylstyrene copolymers generally employs a solution method. In current industrial production, there are three different sol-gel processes before halogenation of butyl rubber, each with significantly different controllable water content in the rubber solution. The wet sol-gel process involves stripping butyl rubber slurry obtained from slurry polymerization with water coagulation to obtain a granular slurry. After simple dehydration of the granular slurry, it is sol-gelled, followed by further dehydration of the rubber solution. This sol-gel process can control a minimum water content of 0.3 wt% in the rubber solution, but this is almost impossible to achieve in actual production. In practice, the water content of the rubber solution is typically controlled within the range of 0.7 wt% to 1.5 wt%. The dry sol-gel process involves stripping butyl rubber slurry obtained from slurry polymerization with water coagulation to obtain a granular slurry. This granular slurry undergoes a complete dehydration and post-treatment drying system to obtain a completely dry base rubber, which is then sol-gelled. The water content of the rubber solution can be controlled between 300 ppm and 1500 ppm. The hexane stripping sol process directly uses hot hexane solvent to strip chloromethane and unreacted monomers from butyl rubber slurry. While removing chloromethane and monomers, the rubber particles dissolve in hexane, directly yielding the sol for halogenation. The water content of the sol can be controlled below 100 ppm. Currently, the industrial halogenation reaction of butyl rubber is mainly carried out in tubular reactors, where the reaction time and temperature are not adjustable. However, the halogenation reaction time of isomonoolefin-alkylstyrene copolymers is highly dependent on the water content of the sol and the reaction temperature.

[0004] On the other hand, hydrogen halide byproducts are generated during the halogenation reaction of isomonoolefin-alkylstyrene copolymers. In the absence of acid-electrolyting agents such as water, alcohols, or alkalis, and with a severe lack of halogen free radicals, hydrogen halide can induce a dehalogenation side reaction of benzyl halide under the influence of light, heat, or free radical initiators. The resulting large benzyl free radicals undergo coupling reactions, and when the reaction proceeds to a certain extent, a significant gel will form, especially in the middle and later stages of the reaction. Therefore, it is necessary to remove the generated hydrogen halide in a timely manner. A common method is to add alkaline compounds, such as carbonates, bicarbonates, and basic oxides. However, these substances are solid at room temperature and cannot be directly added to the halogenation reactor in industrial production. Another method is to add alcohols, such as monohydric alcohols, dihydric alcohols, trihydric alcohols, and tetrahydric alcohols. However, alcohols react with hydrogen halide to produce halogenated hydrocarbons and water, which not only reduces the halogenation reaction rate but also leaves residual halogenated hydrocarbon impurities in the product, affecting product quality.

[0005] To achieve flexible adjustment of the halogenation reaction time of isomonoolefin-alkylstyrene copolymers and effectively remove byproducts of the halogenation reaction without affecting product quality, it is necessary to develop a method for preparing halogenated isomonoolefin-alkylstyrene copolymers suitable for industrial-scale production with low gel content in the product. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems in existing methods for preparing halogenated copolymers, particularly halogenated isomonoolefin-alkylstyrene copolymers, where byproducts cannot be effectively removed and the product has a high gel content. This invention provides a method for preparing halogenated copolymers and its applications, as well as a system for preparing halogenated copolymers and its applications. In this preparation method, by introducing nitrogen gas during the halogenation reaction stage, not only can the occurrence of side reactions be suppressed and the gel content of the product reduced, but most of the byproduct hydrogen halide is also carried away, reducing the amount of alkaline substances used in the subsequent neutralization reaction.

[0007] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a halogenated copolymer, characterized in that the preparation method includes the following steps:

[0008] S1. The copolymer solution, halogenating reagent and halogenating initiator are subjected to a halogenation reaction to obtain the halogenated copolymer solution;

[0009] S2. In the presence of an alkaline substance, the halogenated copolymer solution is neutralized to obtain a halogenated copolymer;

[0010] The halogenation reaction is an N-stage halogenation reaction, in which nitrogen gas is introduced, and N≥2.

[0011] A second aspect of the present invention provides a system for preparing halogenated copolymers, characterized in that the system comprises N halogenation reactors 1, neutralization reactors 2, and transfer pumps 4;

[0012] The copolymer solution, halogenating reagent and halogenating initiator are introduced into the halogenating reactor 1 to carry out the halogenation reaction and obtain the halogenated copolymer solution.

[0013] The halogenated copolymer solution is fed into the neutralization vessel 2 via a transfer pump 4, where it comes into contact with an alkaline substance to undergo a neutralization reaction, thereby obtaining the halogenated copolymer.

[0014] Nitrogen gas is introduced into the Nth halogenation reactor 1, where N≥2.

[0015] The third aspect of the present invention provides the application of the method for preparing the halogenated copolymer described in the first aspect and / or the system for preparing the halogenated copolymer described in the second aspect in the preparation of the halogenated copolymer.

[0016] In the preparation method of the halogenated copolymer provided by the present invention, nitrogen gas is introduced during the halogenation reaction stage, which can not only suppress the occurrence of side reactions and reduce the gel content of the product, but also carry away most of the by-product hydrogen halide, reducing the amount of alkaline substances used in the subsequent neutralization reaction.

[0017] Furthermore, the method for preparing the halogenated copolymer provided by this invention does not introduce any additional impurities, thus ensuring the quality of the final halogenated copolymer. On the other hand, nitrogen and hydrogen halides can be recycled after separation, reducing costs and facilitating large-scale industrial production. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart of the preparation method of the halogenated copolymer of the present invention.

[0019] Explanation of reference numerals in the attached figures

[0020] 1-1, First halogenation reactor; 1-2, Second halogenation reactor; 1-3, Third halogenation reactor; 2, Neutralization reactor; 3, Separation equipment; 4, Transfer pump. Detailed Implementation

[0021] 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.

[0022] The first aspect of the present invention provides a method for preparing a halogenated copolymer, characterized in that the preparation method includes the following steps:

[0023] S1. The copolymer solution, halogenating reagent and halogenating initiator are subjected to a halogenation reaction to obtain the halogenated copolymer solution;

[0024] S2. In the presence of an alkaline substance, the halogenated copolymer solution is neutralized to obtain a halogenated copolymer;

[0025] The halogenation reaction is an N-stage halogenation reaction, in which nitrogen gas is introduced, and N≥2.

[0026] In this invention, during the preparation of the halogenated copolymer, nitrogen gas is introduced into the Nth stage of the halogenation reaction. This not only inhibits the occurrence of side reactions and reduces the gel content of the product, but also carries away most of the byproduct hydrogen halide, reducing the amount of alkaline substances used in the subsequent neutralization reaction.

[0027] Furthermore, the method for preparing the halogenated copolymer provided by this invention does not introduce any additional impurities, thus ensuring the quality of the final halogenated copolymer. On the other hand, nitrogen and hydrogen halides can be recycled after separation, reducing costs and facilitating large-scale industrial production.

[0028] According to the present invention, N is 2-3.

[0029] According to the present invention, the molar ratio of nitrogen to the halogenating reagent is 1-10:1.

[0030] In this invention, when the molar ratio of nitrogen to halogenating reagent is controlled to meet the above-mentioned range, nitrogen can remove most of the byproduct hydrogen halide and inhibit the occurrence of side reactions, ultimately reducing the gel content of the product.

[0031] Furthermore, the molar ratio of nitrogen to the halogenating reagent is 4-6:1.

[0032] According to the present invention, the temperature of the nitrogen gas is 40-70°C and the pressure is 120-350 kPa.

[0033] In this invention, when the temperature and pressure of the nitrogen gas are controlled to meet the above-mentioned range, the nitrogen gas distribution is more uniform, making it easier to control the halogenation reaction rate.

[0034] Furthermore, the nitrogen gas has a temperature of 52-60°C and a pressure of 130-300 kPa.

[0035] According to the present invention, the copolymer content in the copolymer solution is 5-20 wt%, preferably 8-15 wt%.

[0036] According to the present invention, the water content of the copolymer solution is less than 0.3 wt%.

[0037] In this invention, controlling the water content in the copolymer solution to meet the above-mentioned range ensures the halogenation reaction and makes it easy to control the halogenation reaction rate.

[0038] Furthermore, the water content of the copolymer solution is 0.001-0.2 wt%.

[0039] According to the present invention, the copolymer solution is an alkane solution of isobutylene-p-methylstyrene copolymer.

[0040] In this invention, the type of alkane is not particularly limited and can be any conventional alkane solvent in the art, such as C4-C8 straight-chain, branched, or cyclic alkanes, including n-butane, isobutane, n-pentane, isopentane, neopentane, cyclopentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,3-dimethylbutane, cyclohexane, methylcyclopentane, n-heptane, 2-methylhexane, 3-methylhexane, 2-ethylpentane, and 3-ethylpentane. At least one of 2,3-dimethylpentane, 2,4-dimethylpentane, n-octane, 2-methylheptane, 3-methylheptane, 4-methylheptane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, 3-ethylhexane, 2,2,3-trimethylpentane, 2,3,3-trimethylpentane, 2,4,4-trimethylpentane, and 2-methyl-3-ethylpentane, preferably n-hexane and / or cyclohexane.

[0041] In this invention, the type of halogenation initiator is not particularly limited. It can be any conventional free radical initiator in the art capable of promoting the reaction of copolymers, especially isomonoolefin-alkylstyrene copolymers, with halogens. Preferably, it is an oil-soluble free radical initiator, such as an azo radical initiator, preferably selected from at least one of azobisisobutyronitrile, azobisisovalerate, and azobisisoheptanenitrile. In this invention, the amount of halogenation initiator is not particularly limited, as long as the amount of halogenation initiator is sufficient to initiate the halogenation reaction. Preferably, the weight ratio of the halogenation initiator to the copolymer is 0.01-1:100, more preferably 0.05-0.5:100.

[0042] In this invention, the halogenation initiator is preferably provided in solution form, and the solvent is preferably the same as the solvent of the isomonoolefin-alkylstyrene copolymer solution.

[0043] According to the present invention, the halogenating agent is selected from bromine and / or chlorine, preferably bromine.

[0044] According to the present invention, the molar ratio of the halogenation initiator to the halogenation reagent is 0.01-0.5:1.

[0045] In this invention, when the molar ratio of the halogenation initiator to the halogenation reagent is controlled to meet the above-mentioned range, the initiator can ensure the occurrence of the halogenation reaction and achieve control over the halogenation reaction rate.

[0046] Furthermore, the molar ratio of the halogenation initiator to the halogenation reagent is 0.02-0.2:1.

[0047] According to the present invention, the conditions for the halogenation reaction include: a reaction temperature of 40-70°C and an operating pressure of 110-300 kPa.

[0048] In this invention, the halogenation reaction is carried out under the above conditions, which ensures the normal progress of the halogenation reaction and enables control of the halogenation reaction rate.

[0049] Furthermore, the conditions for the halogenation reaction include: a reaction temperature of 52-60°C and an operating pressure of 120-250 kPa.

[0050] In this invention, the halogenation reaction time can be adjusted according to the operating temperature and the water content of the solution. For example, the halogenation reaction time is 1-30 min, preferably 4-20 min.

[0051] In one specific embodiment of the present invention, the halogenation reaction is a three-stage halogenation reaction, which includes the following steps:

[0052] The copolymer solution, halogenating reagent, and halogenation initiator were subjected to a first-stage halogenation reaction under first-stage halogenation reaction conditions to obtain a first-stage product;

[0053] The first product is subjected to a second halogenation reaction under two-stage halogenation conditions to obtain a two-stage product.

[0054] The second-stage product was subjected to a third-stage halogenation reaction under nitrogen gas to obtain the halogenated copolymer solution.

[0055] In this invention, the conditions for the first-stage halogenation reaction, the second-stage halogenation reaction, and the third-stage halogenation reaction each independently include: a reaction temperature of 40-70°C; an operating pressure of 110-300 kPa; and a reaction time of 1-30 min.

[0056] In this invention, the operating pressure P1 of the first-stage halogenation reaction, the operating pressure P2 of the second-stage halogenation reaction, and the operating pressure P3 of the third-stage halogenation reaction satisfy the following condition: P3≤P2≤P1.

[0057] In this invention, by controlling the pressure of the three-stage halogenation reaction to meet the above-mentioned range, it is possible to ensure that the material enters the next reactor from the previous reactor.

[0058] Furthermore, P1-P2 is 10-50 kPa, and P1-P3 is 50-100 kPa.

[0059] According to the present invention, the alkaline substance is selected from potassium hydroxide and / or sodium hydroxide, preferably sodium hydroxide.

[0060] According to the present invention, the molar ratio of the alkaline substance to the halogenating reagent is 0.1-1:1.

[0061] In this invention, when the molar ratio of the alkaline substance to the halogenating reagent is controlled to meet the above-mentioned range, it can be ensured that the hydrogen halide generated by the halogenation reaction is completely neutralized by the alkaline substance, so that the product quality of the obtained halogenated copolymer is stable and the product has a low gel content.

[0062] Furthermore, the molar ratio of the alkaline substance to the halogenating reagent is 0.3-0.8:1.

[0063] In this invention, the amount of alkaline substance used is such that the pH value of the halogenated copolymer solution reaches 8-10.

[0064] In this invention, the alkaline substance is preferably provided in the form of a solution, for example, in the form of a hot aqueous solution.

[0065] According to the present invention, the conditions for the neutralization reaction include: an operating temperature of 60-90°C and a neutralization time of 5-40 min.

[0066] Furthermore, the conditions for the neutralization reaction include: an operating temperature of 70-80°C and a neutralization time of 10-30 min.

[0067] A second aspect of the present invention provides a system for preparing halogenated copolymers, characterized in that the system comprises N halogenation reactors 1, neutralization reactors 2, and transfer pumps 4;

[0068] The copolymer solution, halogenating reagent and halogenating initiator are introduced into the halogenating reactor 1 to carry out the halogenation reaction and obtain the halogenated isomonoolefin-alkylstyrene copolymer solution.

[0069] The halogenated copolymer solution is fed into the neutralization vessel 3 via a transfer pump 4, where it comes into contact with an alkaline substance to undergo a neutralization reaction, thereby obtaining the halogenated copolymer.

[0070] Nitrogen gas is introduced into the Nth halogenation reactor 1, where N≥2.

[0071] In the system for preparing halogenated copolymers provided by this invention, nitrogen gas is introduced into the Nth halogenation reactor 1 to contact the products of the halogenation reaction. This not only inhibits the occurrence of side reactions during the halogenation reaction and reduces the gel content of the product, but also carries away most of the byproduct hydrogen halide, reducing the amount of alkaline substances used in the subsequent neutralization reaction.

[0072] According to the present invention, N is 2-3.

[0073] According to the present invention, the halogenation reactor is a vertical stirred tank, preferably a jacketed vertical stirred tank.

[0074] In this invention, hot water and / or hot oil are preferably introduced into the jacket of the vertical stirring vessel for heating and heat preservation.

[0075] According to the present invention, the agitator in the vertical mixing vessel is selected from at least one of a ribbon agitator, a turbine agitator, and an anchor agitator.

[0076] In this invention, preferably, the neutralization vessel 2 is equipped with a mechanical stirrer and / or a jacket, in which hot water and / or hot oil are circulated for heating and heat preservation.

[0077] According to the present invention, the system further includes a separation device 3.

[0078] According to the present invention, the separation device 3 is used to separate nitrogen and hydrogen halide from the top of the Nth reactor 1 to obtain hydrogen halide and nitrogen.

[0079] In this invention, the preparation method of the halogenated copolymer does not introduce any additional impurities, thus ensuring the quality of the final halogenated copolymer. Preferably, the separated nitrogen gas is returned to the Nth reactor 1 for the halogenation reaction, realizing the recycling of nitrogen gas, reducing costs, and facilitating large-scale industrial production.

[0080] The third aspect of the present invention provides the application of the method for preparing the halogenated copolymer described in the first aspect and / or the system for preparing the halogenated copolymer described in the second aspect in the preparation of the halogenated copolymer.

[0081] One specific embodiment of the present invention is as follows: Figure 1 As shown, the preparation method of the halogenated copolymer includes the following steps:

[0082] (1) The copolymer solution, halogenating reagent and halogenating initiator are introduced into halogenating reactor 1-1. Under the conditions of a first-stage halogenating reaction, the first-stage halogenating reaction is carried out to obtain a first-stage product.

[0083] (2) The first product is fed into the halogenation reactor 1-2, and the second halogenation reaction is carried out under the conditions of the second halogenation reaction to obtain the second product;

[0084] (3) The second-stage product is introduced into the halogenation reactor 1-3. Nitrogen gas is introduced into the bottom of the halogenation reactor 1-3. Under the three-stage halogenation reaction conditions, the third-stage halogenation reaction is carried out. The halogenated copolymer solution is obtained in the halogenation reactor 1-3, and a mixed gas containing nitrogen and hydrogen halide is obtained at the top of the halogenation reactor 1-3.

[0085] (4) The halogenated copolymer solution is fed into the neutralization vessel 2 via the transfer pump 4 and neutralized by contact with alkaline substances to obtain the halogenated copolymer.

[0086] (5) The mixed gas containing nitrogen and hydrogen halide is separated into hydrogen halide and nitrogen by separation device 3, and the nitrogen is returned to halogenation reactor 1-3.

[0087] The present invention will be described in detail below through embodiments.

[0088] In the following examples, the gel rate test method is as follows: Take W2 grams of halogenated copolymer, cut it into pieces, wrap the pieces in a cylinder made of filter paper with a mass of W1 grams, place it in a Soxhlet extractor, use tetrahydrofuran as the extractant, reflux for 8 hours, then take out the filter paper cylinder, dry it, and weigh it. At this time, the mass of the residual sample and filter paper is W3 grams, then the gel rate % = (W3-W1) / W2×100%.

[0089] Example A

[0090] To illustrate the effect of water content in the copolymer solution on the halogenation reaction, the reaction was considered complete when the deep red color of bromine faded to a pale yellow.

[0091] Example A1

[0092] 400 g of a hexane solution of isobutylene-p-methylstyrene copolymer (10 wt% isobutylene-p-methylstyrene copolymer, 0.015 wt% water) was added to a 1 L three-necked flask. The flask, equipped with a stirrer and containing the glue solution, was fixed in a 56 °C constant temperature water bath and stirred for 30 min. Before the bromination reaction, 0.06 g of azobisisobutyronitrile (ABVN) was weighed and added to a 10 mL volumetric flask, and dissolved in 5 mL of hexane. 0.44 mL of liquid bromine was pipetted into 10 mL of hexane and then added to the glue solution. The hexane solution containing ABVN was then added to initiate the bromination reaction. The bromination reaction was carried out under light-protected conditions. Observation of the color of the glue solution revealed that it turned pale yellow after 6 minutes of bromination and became almost colorless after 8 minutes.

[0093] Examples A2-A4

[0094] The copolymer solution was halogenated according to the method of Example A1, except that the water content of the copolymer solution was different, as shown in Table 1.

[0095] Table 1

[0096] Example A1 Example A2 Example A3 Example A4 Water content, wt% 0.015 0.1 0.2 0.3 Halogenation reaction time, min 6 8 16 >30

[0097] As can be seen from Table 1, the halogenation reaction time increases with the increase of water content in the copolymer solution. Furthermore, when the water content in the copolymer solution is too high, the halogenation reaction time is too long, which is not conducive to industrial production.

[0098] Example B1

[0099] (1) A hexane solution of isobutylene-p-methylstyrene copolymer (10 wt% isobutylene-p-methylstyrene copolymer, 0.015 wt% water), a solution of halogenating reagent liquid bromine, and a solution of halogenating initiator ABVN (2 wt% ABVN) were introduced into halogenation reactor 1-1. Under the conditions of a first-stage halogenation reaction, a first-stage halogenation reaction was carried out to obtain a first-stage product. The mass ratio of ABVN to isobutylene-p-methylstyrene copolymer was 0.2:100, and the molar ratio of ABVN to liquid bromine was 0.03:1. The conditions for the first-stage halogenation reaction were: temperature 56℃, pressure 250 kPa, and time 2 min.

[0100] (2) The first product is fed into the halogenation reactor 1-2, and the second halogenation reaction is carried out under the conditions of the second halogenation reaction to obtain the second product; the conditions of the second halogenation reaction are: temperature 56℃, pressure 200kPa, and time 2min.

[0101] (3) The second-stage product is introduced into halogenation reactor 1-3. Nitrogen gas is introduced into the bottom of halogenation reactor 1-3. Under the three-stage halogenation reaction conditions, the third-stage halogenation reaction is carried out. The halogenated copolymer solution is obtained in halogenation reactor 1-3, and a mixed gas containing nitrogen and hydrogen halide is obtained at the top of halogenation reactor 1-3. The temperature of nitrogen is 56℃, the pressure is 200kPa, and the molar ratio of nitrogen to liquid bromine is 5:1. The conditions for the three-stage halogenation reaction include: temperature 56℃, pressure 150kPa, and time 4min.

[0102] (4) The halogenated copolymer solution is pumped into neutralization vessel 2 via pump 4 and neutralized by contact with an alkaline substance (sodium hydroxide solution at 80°C, sodium hydroxide content 0.5 wt%) to obtain the halogenated copolymer. The neutralization reaction is controlled under the following conditions: temperature 80°C, neutralization time 20 minutes. The pH of the obtained halogenated copolymer solution is 9. The molar ratio of alkaline substance to liquid bromine is 0.6:1.

[0103] (5) The mixed gas containing nitrogen and hydrogen halide is separated into hydrogen halide and nitrogen by separation device 3, and the nitrogen is returned to halogenation reactors 1-3. The amount of materials used in each step, the specific process conditions, and the pH and gel content of the halide copolymer solution are shown in Table 2.

[0104] Examples B2-B8

[0105] The halogenated copolymer was prepared according to the method of Example B1, except that the amount of materials used in each step and the specific process conditions differed from those in Example B1, as shown in Table 2. The pH and gel content of the obtained halogenated copolymer solution are shown in Table 2.

[0106] Comparative Example B1

[0107] The halogenated copolymer was prepared according to the method in Example B1, except that nitrogen gas was introduced during the first halogenation stage at a pressure of 300 kPa. Other parameters are shown in Table 2. The pH and gel content of the obtained halogenated copolymer solution are shown in Table 2.

[0108] Comparative Example B2

[0109] The halogenated copolymer was prepared according to the method in Example B1, except that nitrogen gas was not introduced during the third halogenation stage. Other parameters are shown in Table 2. The pH and gel content of the obtained halogenated copolymer solution are shown in Table 2.

[0110] Comparative Example B3

[0111] The halogenated copolymer was prepared according to the method of Example B1, except that the second and third halogenation stages were not performed, and nitrogen gas was not introduced during the first halogenation stage. Other parameters are shown in Table 2. The pH and gel content of the obtained halogenated copolymer solution are shown in Table 2.

[0112] Table 2

[0113]

[0114]

[0115] Table 2 (continued)

[0116]

[0117]

[0118] As can be seen from Table 1, compared with Comparative Examples B1-B3, the halide copolymer solutions prepared by Examples B1-B8 using the preparation method of the present invention have a low gel content, and the pH of the halide copolymer solutions prepared by Comparative Examples B1-B3 is lower, below 8, indicating that the hydrogen halide in the halogenation reaction products is not sufficiently neutralized. Post-treatment such as drying of the halide copolymer solution will lead to an adverse deterioration in product quality.

[0119] Specifically, in Comparative Example B1, although nitrogen gas was introduced during the first halogenation reaction stage, the nitrogen gas introduced during this stage could not remove the hydrogen halides produced in the second and third halogenation reaction stages because the gel mainly forms in the later stages of the halogenation reaction. This resulted in an unfavorable increase in the gel content of the product. Simultaneously, the nitrogen gas introduced during the first halogenation reaction stage could only remove the hydrogen halides produced in the first stage, while the hydrogen halides produced in the second and third stages could not be removed. Consequently, with the same amount of alkaline substance, the pH of the halogenated copolymer solution after neutralization was lower.

[0120] Compared to Examples B1-B7, in Example B8, the molar ratio of nitrogen to halogenating reagent was too low, resulting in a less effective removal of hydrogen halides. The hydrogen halides could not be completely neutralized, leading to a lower pH value in the resulting halogenated copolymer solution and an unfavorable increase in the gel content of the product.

[0121] Compared to Example B1, the molar ratio of nitrogen to halogenating reagent is increased in Example B7. Although this can further reduce the gel content in the product, the pH of the resulting halogenated copolymer solution increases to above 10, resulting in a waste of alkaline substances.

[0122] 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 method for preparing a halogenated copolymer, characterized in that, The preparation method includes the following steps: S1. The copolymer solution, halogenating reagent and halogenating initiator are subjected to a halogenation reaction to obtain the halogenated copolymer solution; S2. In the presence of an alkaline substance, the halogenated copolymer solution is neutralized to obtain a halogenated copolymer; Wherein, the copolymer solution is a solution of isomonoolefin-alkylstyrene copolymer; the halogenation reaction is an N-stage halogenation reaction, in which nitrogen gas is introduced; 2≤N≤3; the molar ratio of nitrogen gas to the halogenating reagent is 1-10:

1.

2. The production method according to claim 1, wherein The nitrogen gas has a temperature of 40-70℃ and a pressure of 120-350kPa.

3. The production method according to claim 2, wherein, The molar ratio of nitrogen to the halogenating reagent is 4-6:

1.

4. The production method according to any one of claims 1 to 3, wherein The copolymer content in the copolymer solution is 5-20 wt%; And / or, the water content of the copolymer solution is less than 0.3 wt%.

5. The production method according to claim 4, wherein, The copolymer content in the copolymer solution is 8-15 wt%; And / or, the water content of the copolymer solution is 0.001-0.2 wt%.

6. The production method according to any one of claims 1 to 3, wherein The weight ratio of the halogenation initiator to the copolymer is 0.01-1:

100.

7. The preparation method according to any one of claims 1-3, wherein the weight ratio of the halogenation initiator to the copolymer is 0.05-0.5:

100.

8. The production process according to any one of claims 1 to 3, wherein The halogenating agent is selected from bromine and / or chlorine; And / or, the molar ratio of the halogenation initiator to the halogenation reagent is 0.01-0.5:

1.

9. The production process according to any one of claims 1 to 3, wherein The molar ratio of the halogenation initiator to the halogenation reagent is 0.02-0.2:

1.

10. The method of making according to any one of claims 1-3, wherein, The conditions for the halogenation reaction include: a reaction temperature of 40-70℃; an operating pressure of 110-300kPa; and a reaction time of 1-30min.

11. The preparation method according to claim 10, wherein, The conditions for the halogenation reaction include: a reaction temperature of 52-60℃; an operating pressure of 120-250 kPa; and a reaction time of 4-20 min.

12. The method of making according to any one of claims 1-3, wherein, The alkaline substance is selected from potassium hydroxide and / or sodium hydroxide; And / or, the molar ratio of the alkaline substance to the halogenating reagent is 0.1-1:

1.

13. The method of making according to claim 12, wherein, The alkaline substance is sodium hydroxide; And / or, the molar ratio of the alkaline substance to the halogenating reagent is 0.3-0.8:

1.

14. The method of making according to any one of claims 1-3, wherein, The conditions for the neutralization reaction include: an operating temperature of 60-90℃ and a neutralization time of 5-40 min.

15. A system for the preparation method of the halogenated copolymer according to any one of claims 1-14, characterized in that, The system includes N halogenation reactors (1), neutralization reactors (2), and transfer pumps (4); The copolymer solution, halogenating reagent and halogenating initiator are introduced into the halogenating reactor (1) to carry out the halogenation reaction and obtain the halogenated copolymer solution; The halogenated copolymer solution is fed into the neutralization vessel (2) via a transfer pump (4) and neutralized by contact with an alkaline substance to obtain the halogenated copolymer. Nitrogen gas is introduced into the Nth halogenation reactor (1), where 2≤N≤3.

16. The system of claim 15, wherein, The halogenation reactor is a vertical stirred tank.

17. The system of claim 16, wherein, The halogenation reactor is a jacketed vertical stirred tank.

18. The system of claim 16 or 17, wherein, The agitator in the vertical mixing vessel is selected from at least one of a ribbon agitator, a turbine agitator, and an anchor agitator.

19. The system of any of claims 15-17, wherein, The system also includes a separation device (3); The separation device (3) is used to separate nitrogen and hydrogen halide from the top of the Nth reactor (1) to obtain hydrogen halide and nitrogen. And / or, return the nitrogen gas to the Nth reactor (1).

20. The method for preparing the halogenated copolymer according to any one of claims 1-14 or the system for preparing the halogenated copolymer according to any one of claims 15-19 is used in the preparation of the halogenated copolymer.

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