Preparation method of halogenated butyl rubber

[0038] The invention provides a kind of preparation method of halogenated butyl rubber, comprises the following steps:

[0039]a) sending butyl rubber glue, halogenating agent, oxidizing agent and modifier into a halogenation reactor to carry out halogenation reaction to obtain halogenated butyl rubber liquid;

[0040] b) using an alkali metal hydroxide to neutralize the halogenated butyl rubber solution to obtain a primary neutralization solution;

[0041] c) using calcium chloride to carry out secondary neutralization to the primary neutralization solution to obtain a secondary neutralization solution;

[0042] d) removing the solvent from the secondary neutralization solution and drying to obtain halogenated butyl rubber;

[0043] The improver is selected from one or more of stearic acid and stearate;

[0044] The butyl rubber glue is the butyl rubber glue obtained by hexane stripping.

[0045] In the preparation method provided by the invention, in the halogenation reaction unit, in addition to adding the reaction raw materials---the butyl rubber glue obtained by the hexane stripping process and the halogenating agent, an oxidizing agent and an improver (the improver is selected from stearic acid and one or more of the stearates), wherein, the addition of the above-mentioned specific improver can effectively inhibit the isomerization of the Type II secondary structure to the Type III primary structure in the halogenated product, and improve the Type II secondary structure in the product. Bit structure content, thereby improving product quality. At the same time, the utilization rate of the halogenating agent and the oxidizing agent can also be improved. In the neutralization unit, the present invention adopts two-step neutralization, the first step is neutralized as metal hydroxide neutralization, the second step introduces calcium chloride for neutralization, and the water-soluble stearate produced by the halogenation unit is converted into stearic acid, which eliminates the risk of foaming in the subsequent coagulation desolventization system and also reduces negative impacts on the downstream wastewater treatment system.

[0046] Regarding step a): the butyl rubber glue, the halogenating agent, the oxidizing agent and the modifier are sent into a halogenation reactor to carry out a halogenation reaction to obtain a halogenated butyl rubber liquid.

[0047] In the present invention, the butyl rubber glue is the butyl rubber glue obtained by hexane stripping. In principle, the present invention has no special restrictions on the method of obtaining butyl rubber glue by solvent stripping, which is a conventional solvent stripping method well known to those skilled in the art; in order to cooperate with steps a) to c), the quality of halogenated products is further improved , the process of obtaining the butyl rubber glue solution by the solvent stripping method preferably includes:

[0048] S1, contacting the polymer slurry with hexane solvent and catalyst deactivator in a flash tank to obtain glue A;

[0049] S2, sending the glue solution A into a stripping tower, and contacting the hexane vapor in reverse in the stripping tower to obtain glue solution B;

[0050] S3, performing a water addition treatment, a dehydration treatment, a concentration adjustment treatment and a heat exchange treatment on the glue B in sequence to obtain a butyl rubber glue;

[0051] The catalyst kill is a catalyst kill of the residual catalyst in the polymer slurry.

[0052] For step S1: the polymer slurry is contacted with a solvent and a catalyst deactivator in a flash tank to obtain glue A.

[0053] The present invention has no special limitation on the type and source of the polymer slurry, which is the polymer slurry produced when the butyl rubber base rubber is prepared by the slurry method well known to those skilled in the art. For example, using halogenated alkanes as the medium, the monomers are polymerized under the action of a catalyst to obtain polymer slurry.

[0054] The medium used for butyl rubber slurry polymerization usually needs to meet the following conditions: first, the polymer is in a slurry state in the medium; second, it can dissolve monomer and catalyst at the same time; third, it is liquid at the polymerization temperature; therefore, in industry The medium used for polymerization is usually haloalkane, preferably methyl chloride.

[0055] The monomer preferably includes a first monomer and a second monomer. Among them, the first monomer is preferably one or more of C4-C7 isomeric monoolefins, more preferably isobutylene; the second monomer is preferably C4-C14 conjugated dienes and methyl One or more of styrene, more preferably isoprene.

[0056] The catalyst preferably includes a main catalyst and a cocatalyst; wherein the main catalyst is preferably HCl and/or water; the cocatalyst is preferably a Friedel-Crafts catalyst, more preferably BF 3 、TiCl 4 , AlCl 3 , AlEtCl 2 and AlEt 2 One or more of Cl.

[0057] The polymerization temperature of the polymerization reaction is preferably -100°C to -90°C. In the above-mentioned polymerization reaction, there is no special limitation on the usage amount of each material, and it can be carried out according to the conventional ratio of industrial production of butyl rubber in this field. Taking isobutylene/isoprene copolymerization to produce butyl rubber as an example, in normal industrial production, in the mixed material entering the reactor, the concentration of isobutylene is 20wt%-40wt%, and the ratio of isoprene to isobutylene is Between 2.0wt% and 4.0wt%. The above-mentioned polymerization reaction is very fast, and the reaction is completed within milliseconds or even microseconds, and the polymerization product butyl rubber is insoluble in the medium, so the entire polymerization system is a slurry heterogeneous system, and the material in the system is polymer slurry.

[0058] In the present invention, before entering the flash tank, the flow rate, temperature and pressure of the polymer slurry have no special restrictions, that is, there are no special restrictions on the feed parameters of the polymer slurry, and it can be carried out according to the delivery conditions of the conventional production process in this field .

[0059] In the present invention, the water content of the solvent needs to be strictly controlled. During the flashing and stripping process, due to the difference in polarity, the water in the solvent is more likely to enter into the methyl chloride. If the water content of the solvent is too high, it will easily affect the water value of the recovered material after polymerization, which will affect the subsequent polymerization reaction, and then affect the performance of the halogenated butyl rubber product, and bring many adverse effects to the methyl chloride and monomer recovery system. . In this way, the methyl chloride and monomer recovery system needs to add additional drying and impurity removal units, which makes the whole methyl chloride system very large and complex, and will cause a significant increase in the unit consumption of methyl chloride, which has the same problem as the steam stripping method, and loses Advantages of Solvent Stripping. In the present invention, the water content of the solvent is preferably ≤100 ppm, more preferably ≤50 ppm, even more preferably ≤10 ppm.

[0060] In the present invention, before entering the flash tank, there is no special limitation on the process parameters of the solvent, that is, there is no special limitation on the feed parameters of the solvent, and it can be carried out according to the delivery conditions of the conventional production process in this field; as long as most of the methyl chloride and untreated The reaction monomer enters the recovery system and at the same time obtains a suitable concentration of butyl rubber solution. The temperature of the solvent is preferably 30-200°C.

[0061] In the present invention, a catalyst deactivator is also added into the flash tank to deactivate the residual catalyst and active centers in the polymer slurry. In the present invention, there is no special limitation on the type of the catalyst deactivator, and it can be any deactivator known to those skilled in the art that can deactivate the catalyst in the polymer slurry. Preferably, the catalyst deactivator is selected from one or more of alcohol compounds, ether compounds, organic carboxylic acids and derivatives thereof, aldehyde compounds, ketone compounds, organic amines and sulfur-containing compounds, and more Alcohol compounds are preferred.

[0062] Wherein, the alcohol compound is preferably one or more of C1-C8 monohydric alcohols and C1-C8 polyhydric alcohols; the polyhydric alcohols include dihydric alcohols, trihydric alcohols and more polyhydric alcohols. More preferably, the alcohol compound is selected from one or more of methanol, ethanol, propanol, butanol, tert-butanol, ethylene glycol, diethylene glycol and triethylene glycol. The ether compound is preferably one or more of C2-C8 ether compounds; more preferably dimethyl ether, diethyl ether, methyl ethyl ether, n-butyl ether, tetrahydrofuran, 1,4-dioxane and One or several kinds of anisole. The organic carboxylic acid is preferably one or more of C1-C18 organic carboxylic acids; more preferably one or more of formic acid, acetic acid, propionic acid, n-butyric acid, isobutyric acid and stearic acid . The derivative of the organic carboxylic acid is preferably one or more of C2~C20 acyl, nitrile, anhydride and ester; more preferably acetamide, methylacetamide, acetonitrile, acetic anhydride, ethylene propionic anhydride, acetic acid One or more of methyl ester, ethyl acetate and stearate. The aldehyde compound is preferably one or more of C1-C18 aldehyde compounds; more preferably one or more of formaldehyde, acetaldehyde, butyraldehyde and crotonaldehyde. The ketone compound is preferably one or more of C2-C18 ketone compounds; more preferably one or more of acetone, butanone and cyclohexanone. The organic amine is preferably a C1-C18 primary amine (i.e. primary amine, RNH 2 ), C1~C18 secondary amines (i.e. secondary amines, R 2 NH) and C1~C18 tertiary amines (i.e. tertiary amines, R 3 N) one or more; more preferably one or more of methylamine, aniline, ethylenediamine, diisopropylamine and triethanolamine. The sulfur-containing compound is preferably one or more of hydrogen sulfide, sulfide and mercaptan; more preferably one or more of hydrogen sulfide, methyl mercaptan, ethyl mercaptan, methyl sulfide and ethyl sulfide kind.

[0063] The content of the catalyst deactivator in glue A is preferably 50-5000 ppm, more preferably 100-1000 ppm. If the content is too low, the inactivation effect will be poor. If the content is too high, the subsequent halogenation reaction will be affected.

[0064] The polymer slurry, catalyst deactivator and solvent are transported to the flash tank through their respective delivery pipelines. Before being transported to the flash tank, the three delivery pipelines can be merged in advance, that is, the feed of the flash tank The mouth is connected with a feed pipe, and the feed pipe is respectively connected with the delivery pipeline of the polymer slurry, the delivery pipeline of the solvent, and the delivery pipeline of the catalyst deactivator; the catalyst deactivator and the solvent can also be delivered through the same pipeline to the flash tank. The polymer slurry, solvent and catalyst deactivator are conveyed to the above-mentioned feeding pipe through their respective conveying pipes for mixing, and then sent together into the flash tank.

[0065] In the present invention, the working temperature and pressure of the flash tank are not particularly limited, and can be executed according to the process parameters of the conventional production process in this field; in some embodiments of the present invention, the working temperature of the flash tank is 30-70 ℃, the working pressure is 1~5bar. After the above three stocks are fully mixed in the flash tank, most of the methyl chloride and unreacted monomers in the polymer slurry are vaporized, and part of the gas phase solvent is discharged from the top of the flash tank, and then recovered through the recovery system, and the polymerization Most of the methyl chloride and unreacted monomers in the slurry are removed. At the same time, the catalyst deactivator reacts with the catalyst and active center in the polymer slurry to deactivate the catalyst and active center and reduce the adverse effect of the catalyst. The butyl rubber in the polymer slurry is quickly dissolved in a solvent to form a butyl rubber solution, and the butyl rubber solution, i.e. glue A, is obtained at the bottom of the flash tank. The concentration of the glue A is preferably 5wt%-15wt%.

[0066] For step S2: the glue solution A is sent to a stripping tower, and the glue solution B is obtained by reverse contacting with hexane vapor in the stripping tower.

[0067] The present invention has no special restrictions on the flow rate, temperature and pressure of the glue solution A sent to the stripper, that is, the feed parameters of the stripper have no special restrictions, and can be carried out according to the delivery conditions of the conventional production process in this field.

[0068] The present invention does not have special restriction to stripper structure, just can be the conventional stripper of this area; In some embodiments of the present invention, the number of trays in the stripper is 55, and wherein, there is 30 trays, 25 trays in the lower part.

[0069]In the present invention, the glue solution A enters into the stripping tower and is in reverse contact with the hexane vapor. The hexane vapor may come from the solvent vapor separately fed into the stripping tower, or from the bottom material of the tower. In the present invention, the water content of the solvent is preferably ≤100 ppm, more preferably ≤50 ppm, even more preferably ≤10 ppm. The present invention has no special restrictions on the flow rate, temperature and pressure of the hexane vapor, which can be carried out according to the delivery conditions of the conventional production process in the field. In some embodiments of the present invention, the hexane vapor comes from the bottom material of the tower; the purpose of stripping is achieved by heating the circulating material at the bottom of the tower to generate solvent vapor. The present invention has no special restrictions on the operating temperature and pressure of the stripper, and it can be executed according to the process parameters of the conventional production flow in the art; in some embodiments of the present invention, the operating temperature at the bottom of the stripper is 50 to 90 ℃, the working pressure is 0.05~5bar.

[0070] After glue solution A and hexane vapor are reversely contacted in the stripping tower, the residual methyl chloride and unreacted monomer in glue solution A and part of the gas phase solvent form the tower top material, which is discharged from the top of the stripping tower to further remove the glue. Residual methyl chloride and unreacted monomer in liquid A, and glue B is obtained at the bottom of the tower simultaneously. The concentration of the glue B is 5wt%-15wt%, wherein the content of unreacted monomeric isoprene is ≤20ppm, preferably ≤10ppm, more preferably ≤5ppm.

[0071] For step S3: performing a water addition treatment, a dehydration treatment, a concentration adjustment treatment and a heat exchange treatment on the glue solution B in order to obtain a butyl rubber glue solution.

[0072] In the present invention, the purpose of adding water at one time is to further deactivate the residual catalyst in the glue solution, so as to reduce the Mooney drop. The amount of water added in the primary water treatment is preferably 0.1 wt% to 10 wt%, more preferably 0.5 wt% to 5 wt%. In the present invention, the amount of water added refers to the ratio of the mass of water added to the material to the mass of the total material after water is added. The water is preferably deionized water, refer to standard ISO/TC 147.

[0073] In the present invention, the primary water addition treatment is preferably performed under the first high-speed mixing condition; the high-speed mixing can be realized by means of a high-speed mixer with agitation. As preferably, the shear rate of the first high-speed mixing is ≤300s -1; The processing time of the first high-speed mixing is 10-60s. If the shear rate is too low, it is not conducive to the rapid and uniform mixing of the two materials; if the shear rate is too high, the polymer molecular chain is easily broken, resulting in an increase in the Mooney drop. The mixing time has the same result. If the mixing time is too long, on the one hand, the energy consumption will increase, and on the other hand, the Mooney drop will increase due to the breakage of the polymer molecular chain; if the mixing time is too short, it is not conducive to the uniform mixing of the two materials. Under the above mixing conditions, the glue solution is fully mixed with water, and the residual catalyst is terminated, which is beneficial to reduce the Mooney drop.

[0074] Dehydration treatment is carried out after the above-mentioned primary water treatment. There are three purposes of dehydration treatment: one is to reduce the acidic substances after deactivation of the residual catalyst in the glue/water mixed system by removing the water phase, and reduce its negative impact on the subsequent halogenation reaction; the other is to stabilize the glue concentration; It can remove some types of water-soluble catalyst deactivators to avoid the impact on the subsequent halogenation reaction. In the present invention, the dehydration treatment is preferably performed until the water content of the material is 0.1wt%-1.0wt%, more preferably 0.3wt%-1.0wt%. Most of the acidic water is removed through the dehydration treatment, which can reduce its adverse effect on the subsequent halogenation reaction, and can also make the concentration distribution of the obtained glue solution more uniform, which is beneficial to the improvement of the performance of the subsequent halogenated rubber product.

[0075] In the present invention, the dehydration treatment is preferably carried out by means of a standing water-splitting tank, in which most of the water in the material will settle and stratify from the glue to the bottom of the tank by itself; in some of the present invention In an embodiment, the residence time of the material in the standing water separation tank is 6 to 12 hours. If the residence time is too short, the purpose of dehydration and homogenization of the glue cannot be fully achieved; if the residence time is too long, the investment and operation costs are too high, and the dehydration effect will not be much better. After the above-mentioned residence time, the water content of the material can reach the above-mentioned target dehydration amount and basically remain stable.

[0076] In the present invention, in the dehydration treatment, in addition to using a standing water separation tank, a receiving tank and an output tank are preferably connected in parallel, the receiving tank is used to receive the glue and mix it evenly, and the output tank is used to mix the glue after the dehydration treatment. The liquid is sent to the subsequent process.

[0077] After the above-mentioned dehydration treatment, the concentration adjustment treatment is carried out. In the present invention, the concentration adjustment treatment preferably includes concentration-enhancing treatment or concentration-decreasing treatment; If the concentration of the delivered glue solution is too high, the concentration can be reduced by adding metered solvent; the concentration adjustment process can be carried out in the concentration regulator. In the present invention, it is preferred to adjust the concentration so that the material concentration is 5wt%-25wt%, more preferably 10wt%-20wt%.

[0078] It is very difficult to control the concentration of butyl rubber glue, mainly due to the characteristics of butyl rubber polymerization, and the butyl polymerization reactor needs to stop the reaction regularly for cleaning operations. In actual production, there are usually 3 to 5 polymerization reactors. Generally, when one reactor stops the reaction, another reactor starts feeding to ensure that the entire production system is as stable as possible; During the process, the amount of butyl rubber sent to the butyl rubber glue preparation system from the stop reactor gradually decreased, and the amount of butyl rubber sent to the glue preparation system from the reaction kettle that started the reaction gradually increased, resulting in the actual amount of butyl rubber sent to the glue preparation system The amount of butyl rubber is always in a fluctuating state, and the concentration of the resulting butyl rubber glue is no longer stable, and has been in a fluctuating state. This will bring great troubles to the subsequent halogenation reaction and the quality of halogenated butyl rubber products. It is difficult to obtain high-quality halogenated butyl rubber products, and the product quality stability is poor, and it is difficult to achieve continuous large-scale production of qualified halogenated butyl rubber products. However, the present invention sets the concentration adjustment processing step, and carries out the concentration adjustment processing of the glue solution in advance, if the concentration of the glue solution delivered is on the high side, the concentration reduction treatment is carried out, and if the concentration of the glue solution delivered is on the low side, the thickening treatment is carried out, The concentration of the glue solution is kept stable in an appropriate concentration range, thereby overcoming the above-mentioned problems, which is conducive to obtaining high-quality products, and can realize the smooth progress of continuous large-scale production and ensure the stable quality of each batch of products.

[0079] After the above treatment, heat exchange treatment is carried out. The heat exchange treatment can be carried out by means of a heat exchange device to adjust the glue solution to a suitable temperature. In the present invention, the heat exchange treatment preferably makes the material temperature reach 30-60°C. After the above treatment, the glue solution reaches a suitable temperature, which is conducive to improving the quality of subsequent halogenated butyl rubber products.

[0080] Through the above steps S1-S3, the butyl rubber glue is obtained. According to step a), the butyl rubber glue, the halogenating agent, the oxidizing agent and the improver are sent to a halogenation reactor for halogenation reaction to obtain the halogenated butyl rubber glue.

[0081] In the present invention, the halogenating agent is preferably Cl 2 、Br 2 or capable of releasing Cl under halogenation conditions 2 /Br 2 One or more of the compounds, more preferably Br 2 (i.e. bromine). In the present invention, the amount of the halogenating agent is preferably 2.5wt% to 4.0wt% of the amount of dry glue in the butyl rubber glue; in some embodiments of the present invention, the amount is 3.0%, 3.3% or 3.5%.

[0082] Halogenating agent Br 2 For example, the reaction between bromine and butyl rubber is a substitution reaction, that is, when a bromine atom is inserted into the main chain of the polymer, a by-product hydrogen bromide is generated. The reaction formula is as follows:

[0083]

[0084] There are three structures in the produced brominated butyl rubber product: ①TypeI is a structure that does not participate in the bromination reaction, that is, the original butyl rubber structure; ②TypeII is a secondary structure; ③TypeIII is a primary structure, and the primary structure is secondary Structural isomers. Generally speaking, after butyl rubber is brominated, the main structure of the brominated product is a secondary structure. Since the primary structure is thermodynamically more stable than the secondary structure, during the bromination reaction of butyl rubber, a part of the secondary structure will be isomerized into the primary structure. Temperature and the presence of Lewis acids and transition metal ions have an influence on the relative content of primary structures. However, during the isomerization process, the increase of the Type III structure content is inevitably accompanied by the degradation of the polymer and the deepening of the product color.

[0085] When butyl rubber is brominated, the by-product HBr itself is an isomerization catalyst. With the increase of reaction time, the content of TypeIII structure in the product increased, accompanied by severe degradation. The applicant found that during the bromination reaction, the by-product HBr was oxidized to bromine in situ by introducing an oxidizing agent. On the one hand, the reduction of HBr can significantly reduce the isomerization of the product structure; on the other hand, the bromine generated by the oxidation of HBr can continue to participate in the bromination reaction of butyl rubber, which improves the utilization rate of bromine. Generally speaking, as long as the standard electrode potential or substances with higher oxidation ability than bromine can be used as oxidants, such as hypochlorous acid, perchloric acid, hypobromous acid, perbromic acid and its salts, ozone, peroxide Or azo compounds and so on.

[0086] The present invention selects the peroxide oxidizing agent, preferably hydrogen peroxide. Taking the oxidant hydrogen peroxide as an example, the oxidation process of HBr is shown in the following formula 1:

[0087] 2HBr+H 2 o 2 →Br 2 +2H 2 O Formula 1;

[0088] The applicant also found in the research process that the water generated by the oxidation reaction (including the water introduced by the aqueous hydrogen peroxide solution) can dissolve and absorb the bromination reaction by-product HBr, further reducing the isomerization. Therefore, the present invention preferably adopts hydrogen peroxide oxidizing agent. In the present invention, the hydrogen peroxide is preferably introduced in the form of an aqueous solution (ie hydrogen peroxide). The concentration of the hydrogen peroxide is preferably 15wt%˜60wt%. In the present invention, the molar ratio of the oxidizing agent to the halogenating agent is preferably 0.2-3.0; in some embodiments of the present invention, the molar ratio is 0.7, 1.5 or 2.6.

[0089] In the present invention, the improver is one or more of stearic acid and stearate. Described stearate is preferably one or more in sodium stearate, calcium stearate, zinc stearate and magnesium stearate.

[0090] According to the applicant's research, it is found that the introduction of the above-mentioned improver at the same time as the introduction of the oxidizing agent has a better effect on inhibiting the isomerization of the halogenated product, and it is better to increase the utilization rate of the halogenating agent and the oxidizing agent at the same time. On the one hand, the HBr produced by the improver and the halogenation reaction reacts as follows to consume a part of the HBr (taking sodium stearate as an example, the reaction formula is shown in the following formula 2), reducing the isomerization; on the other hand, whether it is hard The fatty acid salt itself, or the reaction product stearic acid, can improve the dispersion effect of the hydrogen peroxide aqueous solution in the butyl rubber glue to a certain extent. Specifically, the dispersed phase of the aqueous hydrogen peroxide solution is more uniformly distributed in the glue solution, and the phase diameter is smaller, thereby improving the utilization rate of the halogenating agent and the oxidizing agent.

[0091] C 17 h 35 COONa+HBr→C 17 h 35 COOH+NaBr Formula 2.

[0092]In the prior art, the halogenated butyl rubber liquid is formed in the halogenation unit, and after the halogenated butyl rubber liquid is neutralized by the neutralization unit, additives such as antioxidants and stabilizers are sometimes added in the post-processing of the rear system, Among them, stearate additives are mainly used as stabilizers to improve the thermal stability of products. And completely different from the prior art, in the present invention, add stearic acid or stearate class improver in the halogenation unit of preorder production link (in the prior art, the halogenation unit usually only adds reaction raw material -- butyl Rubber glue and halogenating agent, without adding other additives); and its effect also changes, in the present invention, it is to suppress the isomerization in the halogenation reaction, improve the content of the halogenated product of Type II secondary structure; it can also improve the efficiency of the oxidant , thereby improving the utilization rate of halogenating agents (such as bromine).

[0093] In the present invention, the mass ratio of the amount of the improver to the amount of dry glue in the butyl rubber glue is preferably (0.001-0.01): 1; in some embodiments of the present invention, the amount is 0.001: 1. 0.005:1 or 0.008:1. If the amount is too low, it will be difficult to effectively improve the halogenation reaction and product quality stability; if the amount is too high, it will increase the difficulty of subsequent neutralization and reduce the utilization rate of the halogenating agent. Once the neutralization is not complete, the residual acidic substances will affect the product. Storage stability and product performance may be negatively affected.

[0094] In the present invention, the temperature of the halogenation reaction is preferably ≤80°C, specifically 20-80°C, more preferably 30-80°C. The time for the halogenation reaction is preferably 3-60 min. After the above halogenation reaction, a halogenated butyl rubber liquid is produced in the halogenation reactor.

[0095] Regarding steps b) to c): the halogenated butyl rubber liquid is neutralized with an alkali metal hydroxide to obtain a primary neutralized liquid; the primary neutralized liquid is neutralized with calcium chloride for a second time to obtain Secondary neutralizer.

[0096] After the halogenation reaction is completed, the halogenated material enters the neutralization system for neutralization reaction. In the present invention, two-step neutralization is carried out; in actual operation, two series-connected neutralization tanks can be set up to carry out neutralization in sequence. In the present invention, the first step of neutralization is first carried out in the first kettle, and the first step of neutralization uses an alkali metal hydroxide as a neutralizing agent, and the alkali metal hydroxide is preferably sodium hydroxide. The first neutralization is mainly to neutralize the residual halogenating agent (such as bromine) and the by-product HBr in the halogenated material to obtain a primary neutralization liquid. In the present invention, the addition amount of the alkali metal hydroxide is preferably such that the pH of the primary neutralization solution reaches 5-12. According to actual production needs, a reducing agent can also be added in the first neutralization process. The reducing agent preferably includes one or more of sodium sulfite, sodium pyrosulfite and sodium thiosulfate. The molar ratio of the reducing agent to the halogenating agent is preferably (0.2˜1.2):1.

[0097] Taking sodium hydroxide neutralizing agent as an example, and using sodium sulfite as a reducing agent, the first kettle neutralization mainly includes the following reactions:

[0098] HBr+NaOH→NaBr+H 2 O;

[0099] C 17 h 35 COOH+NaOH→C 17 h 35 COONa+H 2 O;

[0100] Br 2 +Na 2 SO 3 +2NaOH→Na 2 SO 4 +2NaBr+H 2 O;

[0101] h 2 o 2 +Na 2 SO 3 →Na 2 SO 4 +H 2 O.

[0102] After the first step of neutralization is completed, the resulting primary neutralization liquid enters the second neutralization tank together with calcium chloride for the second step of neutralization. In the second neutralization tank, the main reactions are as follows:

[0103] 2C 17 h 35 COONa+CaCl 2 →Ca(C 17 h 35 COO) 2 +2NaCl converts the sodium stearate produced in the first step of neutralization into calcium stearate by adding calcium chloride.

[0104] In the present invention, depending on the modifier used, the molar ratio of the calcium chloride to the modifier added in the halogenation system is preferably (0.55-1.2): 1; in some embodiments of the invention, the molar The ratio is 0.55:1 or 1.2:1. After the above secondary neutralization, a secondary neutralization solution is obtained.

[0105] Regarding step d): removing the solvent from the secondary neutralization solution and drying to obtain halogenated butyl rubber.

[0106] The present invention has no special restrictions on the method of removing the solvent and drying, and it can be carried out according to the conventional operation in the field, specifically, the secondary neutralization solution and necessary auxiliary agents (such as antioxidant, stabilizer and/or stearin Calcium acid calcium) mixed evenly, sent to the flash tank of the coagulation system to remove the solvent, and at the same time to form colloidal water; then the colloidal water was further removed from the solvent by the stripping tank, and then entered the post-treatment dehydration drying system for dehydration and drying treatment to obtain Finished halobutyl rubber. The water removed by the dehydration drying unit is sent to the bromine-containing sewage treatment plant for wastewater treatment.

[0107] Wherein, the antioxidant is preferably selected from non-polluting hindered phenols, such as Irganox 1010, 1076, 264 and the like. The stabilizer is preferably epoxidized soybean oil. Calcium stearate can also optionally be added directly to the flash tank.

[0108] The improver (stearic acid or stearate) that the present invention introduces in the halogenation reaction process can suppress isomerization and improve the utilization ratio of halogenation agent and oxidizing agent; Simultaneously, stearic acid contained in the material after halogenation enters After neutralizing the system, it reacts with an alkaline substance (sodium hydroxide) to generate sodium stearate. Sodium stearate is a very strong emulsifier. The presence of sodium stearate will have two effects: First, the emulsification of sodium stearate can significantly improve the dispersion effect of oil-water two-phase, improve the neutralization efficiency, reduce Residues of acidic substances such as stearic acid in the glue. But on the other hand, when sodium stearate enters the follow-up coagulation system (i.e. the follow-up coagulation desolventization link), there will be obvious foaming. The system brings great troubles; at the same time, sodium stearate is a water-soluble substance, which makes the COD of sewage entering the bromine-containing salt sewage treatment system increase accordingly, and the reverse osmosis system in the sewage treatment system will be greatly affected, and the treatment capacity will also be reduced. will drop accordingly. However, the present invention introduces calcium chloride for secondary neutralization and converts sodium stearate into calcium stearate. On the one hand, the risk of foaming in the subsequent coagulation system is eliminated, and the negative impact on the sewage treatment system is also reduced. At the same time, as mentioned earlier, the converted calcium stearate itself is one of the necessary additives for halogenated butyl rubber products. In the prior art, calcium stearate is only added in the glue solution after the neutralization reaction is completed or in the flash kettle. It has three functions, the first is the release agent of the colloidal particles in the colloidal water system to control the particle size of the colloidal particles in the colloidal water system; The vulcanization speed of the product; third, calcium stearate is also a heat stabilizer for halogenated butyl rubber.

[0109] The preparation method of halogenated butyl rubber provided by the invention has the following beneficial effects:

[0110] (1) Introducing a modifier (stearic acid or stearate) into the halogenation reaction to produce the following effects: one is to improve the effect of the halogenation reaction, inhibit isomerization, and increase the utilization rate of the halogenation agent and oxidant; With the cooperation of calcium chloride, the risk of foaming in the subsequent coagulation system is eliminated, and at the same time, it does not add additional burden to the sewage treatment system containing bromine salt; the third is that it does not bring additional components to the halogenated butyl rubber product, To prevent unpredictable product quality risks.

[0111] (2) Adopt hydrogen peroxide as oxidizing agent, can reduce isomerization, can also improve the utilization ratio of halogenating agent (bromine).

[0112] (3) Calcium chloride is introduced into the neutralization unit for secondary neutralization, and the stearic acid or stearate by-products introduced by the front halogenation unit are converted into useful additives and at the same time play the role of defoaming, eliminating the subsequent The risk of foaming in the coagulation system also reduces negative impacts on the sewage system.

[0114] Example 1

[0115] use figure 2 The device shown was prepared, figure 2 It is a schematic diagram of the production equipment used in the examples of the present invention. Among them, 1-6 are systems for preparing butyl rubber glue, and 7-12 are systems for preparing butyl rubber glue into halogenated butyl rubber. Specifically: 1 is a polymerization reactor, 2 is a flash tank, 3 is a stripper, 4 is the first high-speed mixer, 5 is a buffer device, 6 is a concentration regulator; 7 is a halogenation reactor, 8 and 9 are Neutralization system (8 is the first tank, 9 is the second neutralization tank), 10 is the flash tank, 11 is the stripping tank, and 12 is the drying system.

[0116] 1.1 Preparation of butyl rubber glue:

[0117] With methyl chloride as the medium, AlEtCl 2 and HCl as catalyst (AlEtCl 2 : The mass ratio of HCl is 18:1), and isobutylene and isoprene are monomers (the mass ratio of isobutylene:isoprene is 100:3). AlEtCl 2 Dissolve in methyl chloride to obtain a catalyst solution with a concentration of 0.3 wt% and a flow rate of 0.6 kg/h. The concentration of the mixed material obtained by mixing the monomer and methyl chloride is 30 wt%, and the flow rate is 10 kg/h. The polymerization reaction was carried out in the polymerization reactor 1 (the polymerization temperature was -95° C.), and the monomer conversion rate was 90%.

[0118] The above polymer slurry is sent to the flash tank 2 (flow rate 10.6kg/h, temperature -93°C, pressure 2bar), at the same time, the hexane hot solvent and ethanol deactivator are sent to the flash tank through the pipeline 2-1 2. The flow rate of hot hexane is 25.0kg/h, the temperature is 138°C, and the pressure is 6bar; the flow rate of ethanol is 23.6g/h, the temperature is 25°C, and the pressure is 6bar. After the three shares of materials were mixed in the flash tank 2, most of the methyl chloride, unreacted monomer and part of hexane were discharged from the top of the flash tank 2 into the methyl chloride recovery system (during discharge, the flow rate of this part of the material was 11.7kg/h , a temperature of 50°C and a pressure of 1.51 bar). A hexane solution of butyl rubber was obtained at the bottom of the tank, that is, glue solution A, with a concentration of 11.3 wt % and an ethanol content of 110 ppm.

[0119]The glue solution A is pumped into the stripping tower 3 through the delivery pump (flow rate 24.0kg/h, temperature is 50°C, pressure 1.52bar), and is in reverse contact with the hexane vapor generated at the bottom of the tower, and the two materials are in reverse contact, so that Part of the methyl chloride and unreacted monomer and part of the gas phase solvent in the glue A form a tower top material, which is discharged from the top of the stripping tower. Simultaneously, remaining glue solution A dissolves in solvent to form tower bottom glue solution. Among them, the tower top material is divided into two stocks, one material (flow rate 2.8kg/h, temperature 41 ℃, pressure 1.21 bar) enters the methyl chloride recovery system together with the decompressed gas phase discharged from the flash tank 2, and the other material It flows back into the stripper 3 through a heat exchanger, a buffer tank and a delivery pump in turn. The glue at the bottom of the tower is also divided into two strands. One strand of glue is sent to the reboiler for reboiling treatment by means of a delivery pump, and then refluxed into the stripping tower 3 to heat the glue at the bottom of the tower; the other glue B (flow rate 21.2kg/h, temperature 84°C, pressure 1.61bar, concentration 12.8wt%, isoprene monomer content 1.6ppm) is sent to the first high-speed mixer 4 through a delivery pump.

[0120] At the same time, water is sent to the first high-speed mixer 4 through the pipeline 4-1 (the flow rate is 1.1 kg/h, the temperature is 25° C., and the pressure is 5 bar). Glue B and water are uniformly mixed in the first high-speed mixer 4, and during the mixing process, the shear rate is 250s -1 , the residence time is 20s, and the amount of water added is 5.0wt%. After mixing, the resulting glue C (at a temperature of 55° C.) is sent to the buffer device 5 (such as image 3 As shown, there are three static water separation tanks, one for receiving glue, one for sending glue, and one for static water separation), and stay in the static water separation tank for 8 hours. During the standing period, a total of 7.9kg of water was discharged from the bottom of the tank to the bromine-containing salt sewage treatment system, and the water content of the dehydrated material was 0.5wt%.

[0121] The dehydrated material is sent to the concentration regulator 6 for concentration treatment, a part of the hexane is steamed out (flow 6.4kg/h, temperature 83°C, pressure 1.71bar), and the glue obtained at the bottom of the tank (concentration is 18.3wt%) , water content 0.37wt%) through a heat exchanger for heat exchange treatment to obtain butyl rubber glue (temperature 40 ° C, water content 0.37wt%, monomer content 1.8ppm).

[0122] 1.2 Preparation of halogenated butyl rubber

[0123] a) transport materials to the halogenation reactor 7, including:

[0124] The butyl rubber glue obtained in step 1.1: flow rate 14.8kg/h, concentration 18.3wt%, water content 0.37wt%, temperature 43°C;

[0125] Bromine: The flow rate is 94.9g/h, and the weight ratio of bromine to dry glue is 35.0:1000;

[0126] Hydrogen peroxide: the concentration is 30wt%, the flow rate is 47.06g/h, and the molar ratio of hydrogen peroxide to bromine is 0.7:1;

[0127] Sodium stearate hexane suspension: concentration 5wt%, flow rate 54.2g/h, the weight ratio of sodium stearate improver and dry gum is 0.001:1.

[0128] The above-mentioned materials were reacted in the halogenation reactor 7 at 50° C. for 5 minutes to obtain a halogenated butyl rubber liquid.

[0129] b) The obtained halogenated butyl rubber liquid is sent into the neutralization system, and first enters the first kettle 8. At the same time, NaOH solution and sodium bisulfite solution are added to the first kettle (the mol ratio of sodium bisulfite to bromine is 0.5: 1), stay in the first kettle for 5 minutes, and the pH of the primary neutralization solution obtained is 8.0.

[0130] c) The resulting primary neutralization solution is sent to the second neutralization tank 9, and calcium chloride is added (the molar ratio of the calcium chloride dosage and the sodium stearate improver added in the halogenation unit is 0.55:1), The secondary neutralization tank was left to react for 5 minutes to obtain a secondary neutralization solution.

[0131] d) The secondary neutralization liquid is sent to the condensation unit (composed of the flash tank 10 and the stripping tank 11), and the high-temperature water vapor enters the flash tank and the stripping tank through the pipelines 10-1 and 11-1 respectively, and is removed solvent. Finally, it enters the drying system 12 to remove moisture to obtain bromobutyl rubber. At the same time, the sewage separated from the drying system enters the downstream bromine-containing salt sewage treatment system for bromine salt separation and sewage recovery treatment.

[0132] 1.3 Performance testing

[0133] The bromobutyl rubber products were characterized by primary site structure, Mooney drop test, bromine content analysis and gel content test. Among them, the structural characterization of the brominated product adopts the AVANCE400MHz NMR wave spectrum instrument of Swiss Bruker Company, the magnetic field strength is 9.40 tesla, and the diameter of the sample tube is 5mm. As an internal standard, tested at room temperature. The Mooney of the polymer is determined according to the standard ASTM D1646, and the instrument model used is Alpha MV2000. The bromine content of the brominated product was obtained by XRF. XRF adopts the external standard method, so the instrument is Rigaku Supermini200. The gel content of the brominated product was obtained by centrifugation: firstly, the sample (the sample was taken after neutralization and before the addition of additives) was dissolved in toluene at 25°C for 30 minutes at a concentration of 12.5g/l, and then the sample was dissolved in an ultracentrifuge (20000rpm) at 25°C for 1 hour, the insoluble matter was taken out and then dried to calculate the gel content of the sample.

[0134] The test results show that the Mooney drop of the obtained bromobutyl rubber is 10.5%; the content of the primary position III structure in the brominated structure in the bromobutyl rubber product is 10.2%; the gel content of the product is 0.10wt%. The bromine content of the bromobutyl rubber product is 2.09wt%, and the bromine utilization rate is calculated to be 59.71%.

[0135] Example 2

[0136] 1.1 Preparation of butyl rubber glue

[0137] Prepare butyl rubber glue according to the preparation process of Example 1, the difference is that the catalyst deactivator added in flash tank 2 is n-butyl ether, and the n-butyl ether content in glue A is 210ppm; add the first high-speed mixing The amount of water added to device 4 is 3.5wt%. After the heat exchange treatment of the heat exchanger, the temperature of the glue solution is 40°C. The concentration of the final butyl rubber solution is 18.3wt%, the monomer content is 1.9ppm, and the water content is 0.37 wt%, the temperature is 40°C.

[0138] 1.2 Preparation of halogenated butyl rubber

[0139] Utilize gained butyl rubber solution to prepare brominated butyl rubber according to the preparation process of embodiment 1, difference is:

[0140] Bromine sent to the halogenation reactor: the flow rate is 89.5g/h, the weight ratio of bromine to dry glue is 33.0:1000; hydrogen peroxide: the flow rate is 44.38g/h, and the molar ratio of hydrogen peroxide to bromine is 0.7: 1; the improving agent that adopts is calcium stearate, and calcium stearate hexane suspension: concentration 5wt%, flow rate 271.2g/h, the weight ratio of calcium stearate improving agent and dry glue is 0.005: 1. In the neutralization system, the molar ratio of the calcium chloride added in the second neutralization tank to the calcium stearate improver added in the halogenation unit is 1.2:1.

[0141] According to the test method of Example 1, various parameters of the obtained bromobutyl rubber were tested, and the results are shown in Table 1.