A chloroprene monomer refining and polymerization device and a chloroprene monomer refining method

Abstract

The invention belongs to the field of monomer refining technology in the process of preparing chloroprene rubber, and specifically relates to a method for improving the quality of chloroprene monomer, which can reduce the impurity content in chloroprene monomer. The method has a simple process flow, and the chloroprene monomer impurities are treated by increasing the molecular sieve adsorption and screening process, and the monomer impurity content is reduced, thereby improving the quality of rubber products. The treatment method of the present invention is easy to implement, economical and environmentally friendly, the molecular sieve can be reused after regeneration treatment, and the screening effect is equivalent to the first use effect. The present invention is particularly better for the treatment of methyl vinyl ketone and 4-chloro-2-butanone, dimer, and inhibitor. By comparing the emulsion polymerization experimental results and the chloroprene rubber test results, it can be seen that the monomer quality has a more obvious effect on the emulsion polymerization and rubber quality, and the rubber comprehensive performance obtained by the emulsion polymerization of the chloroprene monomer after treatment is better, and the emulsion polymerization process is stable without gel phenomenon.

Description

Technical Field

[0001] The invention belongs to the technical field of monomer refining in the process of preparing chloroprene rubber, and specifically relates to a chloroprene monomer refining and polymerization device and a chloroprene monomer refining method. Background Art

[0002] Chloroprene monomer is a colorless organic flammable liquid, slightly soluble in water, with a boiling point of 59.4°C and is volatile. Chloroprene is polymerized by emulsion polymerization to obtain chloroprene polymer, namely chloroprene rubber. Since DuPont first produced chloroprene rubber in 1930, it has a history of more than 90 years. Because its polymer molecules contain polar chlorine atoms, it can reduce the activity of double bonds while increasing the stability of the polymer, making chloroprene rubber have excellent oil resistance, corrosion resistance, ozone resistance, flame resistance and good mechanical properties. Therefore, chloroprene rubber can never be completely replaced.

[0003] The quality of chloroprene monomer is the key to the performance of chloroprene rubber. The industrial production of chloroprene mainly includes the carbide acetylene method and the butadiene method. Due to the abundant domestic calcium carbide resources and low cost, and the high technical requirements and large initial investment of the butadiene method, domestic manufacturers currently use the carbide acetylene method to prepare chloroprene. Although the domestic production of chloroprene rubber has a history of more than 60 years, there is still a large gap between the monomer quality and rubber quality and the international advanced level.

[0004] The production of chloroprene by the carbide acetylene method mainly includes two process steps. First, acetylene dimerizes to form vinyl acetylene; then, vinyl acetylene undergoes an addition reaction to form chloroprene. The reaction equation is as follows:

[0005] .

[0006] In addition to the above main reactions, a large number of side reactions also occur in the process of producing chloroprene by carbide acetylene, thus producing methyl vinyl ketone (MVK), vinyl acetylene (MVA), divinyl acetylene (DVA), 4-chloro-2-butanone (X 2 ), peroxide and other impurities, and the presence of these impurities directly affects the chloroprene rubber emulsion polymerization process, and ultimately leads to a decrease in the performance of rubber products. The effects of impurities in chloroprene on emulsion polymerization and rubber are shown in Table 1.

[0007] Table 1 Effects of impurities in chloroprene on emulsion polymerization and rubber

[0008]

[0009] Therefore, improving monomer quality and reducing impurity content are key steps to improve chloroprene rubber. At present, there are literature reports on the impact of related impurities on chloroprene rubber, but some impurities have not yet been systematically studied, and there are few reports on how to remove these impurities. Summary of the invention

[0010] The object of the present invention is to provide a chloroprene monomer refining and polymerization device and a chloroprene monomer refining method, that is, to reduce the impurity content in the chloroprene monomer, especially to treat methyl vinyl ketone and 4-chloro-2-butanone, dimer, and inhibitor better. The method has a simple process flow, and by adding molecular sieve adsorption and screening processes, the chloroprene monomer impurities are treated to reduce the monomer impurity content, thereby improving the quality of rubber products.

[0011] The present invention is realized by the following technical scheme: a chloroprene monomer refining and polymerization device, the device is a chloroprene latex polymerization kettle provided with an impurity removal device, the impurity removal device is a first molecular sieve tower feed port connected to the outlet of a circulation pump, the discharge port of the first molecular sieve tower is connected to the feed port of the second molecular sieve tower, the discharge port of the second molecular sieve tower is connected to the feed port of the polymerization kettle, and the discharge port of the polymerization kettle is connected to the chloroprene latex tank.

[0012] The top of the first molecular sieve tower and the top of the second molecular sieve tower are connected to nitrogen, and the bottom of the first molecular sieve tower (3) and the bottom of the second molecular sieve tower are connected to a chloroprene distillation system.

[0013] The method for refining chloroprene monomer by using the chloroprene monomer refining and monomer polymerization device is specifically as follows: the chloroprene monomer is sent into a first molecular sieve tower through a circulation pump for molecular sieve screening, the screened chloroprene monomer is continuously sent into a second molecular sieve tower for further adsorption screening, and the treated chloroprene monomer is analyzed and determined by gas chromatography; after the chloroprene monomer screening is completed, nitrogen is opened to purge the molecular sieve to ensure that the monomer is completely replaced, the discharge ports of the first molecular sieve tower and the second molecular sieve tower are closed, and the molecular sieve is protected by nitrogen.

[0014] The molecular sieve is any one of 3A molecular sieve, 4A molecular sieve, 5A molecular sieve, 10X molecular sieve, 13X molecular sieve, 13XAPG, ZSM-800, REY, or HY30 molecular sieve.

[0015] The specific method of nitrogen purging molecular sieve is: first use cold nitrogen for the first purge, the temperature of cold nitrogen is controlled at 0-5℃, the purge time is determined according to the gas detection index, and the exhaust gas is analyzed by gas chromatography every 1.5 hours of purge. When the chloroprene detection index is ≤5%, stop the cold nitrogen purge; after the monomer in the molecular sieve is purged clean, hot nitrogen purge is performed to remove the adsorbed impurities for regeneration, the temperature is controlled at 200-500℃, the purge time is 2-6 hours, and finally the cold nitrogen purge is cooled to 20-30℃ before it can be used again.

[0016] Molecular sieve is a kind of aluminosilicate with many micropores. It adsorbs or repels molecules of different substances according to the size of the pores inside its crystal. The adsorption function of molecular sieve is mainly achieved through physical adsorption (van der Waals force). The crystal pores have strong polarity and Coulomb field, and show stronger adsorption capacity for polar molecules (such as water) and unsaturated molecules. The screening function of molecular sieve is because the molecular sieve pore size distribution is very uniform. Only substances with molecular diameters smaller than the pore diameter can enter the crystal pores of molecular sieve, otherwise they are rejected.

[0017] Common types of molecular sieves include 3A molecular sieve, 4A molecular sieve, 5A molecular sieve, 10X molecular sieve, 13X molecular sieve, 13XAPG, ZSM-800, REY, HY30 molecular sieve, etc. Due to the high adsorption capacity and strong selectivity of molecular sieves, they have been widely used in organic chemical and petrochemical industries, such as drying of various liquids, gases, refrigerants, ethylene, acetylene, propylene, butadiene, etc. However, there have been no relevant reports on their application in the refining of chloroprene monomer.

[0018] Compared with the prior art, the present invention has better treatment effects on methyl vinyl ketone, 4-chloro-2-butanone, dimer and inhibitor. By comparing the results of emulsion polymerization experiment and the test results of chloroprene rubber, it can be seen that the quality of monomer has a significant effect on emulsion polymerization and rubber quality. The rubber obtained by emulsion polymerization of treated chloroprene monomer has better comprehensive performance, and the emulsion polymerization process is stable without gelation.

[0019] The present invention removes some impurities in chloroprene monomer by molecular sieve adsorption screening method, but also considers the application of synthetic rubber and other thermoplastic elastomers in a broader sense. Various polymerized monomers have great commonality. The impurities, synthetic by-products and polar molecules in the monomers have great consistency in material properties and principles. This method is applied to treat polymerized monomers in a broader sense, but is not limited to the scope of the present invention.

[0020] The embodiment of the present invention only compares and analyzes different types of molecular sieves and the treatment of chloroprene impurities by using different types of molecular sieves in combination, and does not optimize the best experimental conditions. According to known technologies, the screening effect is related to the type of molecular sieve, the contact time between the monomer and the molecular sieve, the contact area and other factors have a certain relationship. The ratio between the cross-sectional area diameter and the column height of the molecular sieve packing column of the present invention is 1: (3-10), and the experimental scheme can be optimized by orthogonal test, and better experimental results can be obtained by combining various factors.

[0021] The present invention only verifies that some impurities in chloroprene monomer can be removed by molecular sieve adsorption and screening methods, but also takes into account the application of synthetic rubber and other thermoplastic elastomers in a broader sense. Various polymerized monomers have great commonality, and the impurities, synthetic by-products, and polar molecules in the monomers have great consistency in material properties and principles. This method is applied to treat polymerized monomers in a broader sense, and is not limited to the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of the chloroprene monomer refining and monomer polymerization device of the present invention;

[0023] In the figure: 1-polymerization kettle; 2-circulation pump; 3-first molecular sieve tower; 4-second molecular sieve tower; 5-chloroprene rubber latex tank; 6-chloroprene distillation system. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, and the disclosure and materials cited therein are hereby incorporated by reference.

[0026] Technical equivalents to the specific embodiments described that are apparent to those skilled in the art using no more than routine experimentation are intended to be encompassed by this application.

[0027] The experimental methods in the following examples are all conventional methods unless otherwise specified. The instruments and equipment used in the following examples are all conventional laboratory instruments and equipment unless otherwise specified; the experimental materials used in the following examples are all purchased from conventional biochemical reagent stores unless otherwise specified.

[0028] 1. Experimental instruments and materials: glass tube chromatograph, circulation pump, beaker, conical flask, iron stand, glass tube, silicone tube, nitrogen, chloroprene monomer, molecular sieve, experimental polymerization kettle, rubber testing instrument.

[0029] Analytical instruments: SP-3420 gas chromatograph, BF-2002 chromatography workstation; detector type: hydrogen flame ionization; injector split ratio: 30:1; temperature: 250°C.

[0030] Chloroprene monomer refining and polymerization equipment, such as Figure 1 As shown, the device is a chloroprene latex polymerization kettle 1 equipped with an impurity removal device, wherein the impurity removal device is a first molecular sieve tower 3 feed port connected to the outlet of a circulating pump 2, the first molecular sieve tower 3 discharge port is connected to the feed port of a second molecular sieve tower 4, the second molecular sieve tower 4 discharge port is connected to the feed port of the polymerization kettle 1, and the discharge port of the polymerization kettle 1 is connected to a chloroprene latex tank 5.

[0031] The top of the first molecular sieve tower 3 and the top of the second molecular sieve tower 4 are connected to nitrogen, and the bottom of the first molecular sieve tower 3 and the bottom of the second molecular sieve tower 4 are connected to the chloroprene distillation system 6.

[0032] 2. Experimental methods

[0033] Glass tube chromatography column specifications: 600mm / 24×24; filler models: 3A molecular sieve, 4A molecular sieve, 5A molecular sieve, 10X molecular sieve, 13X molecular sieve, ZSM-800, HY30; filler height: 50cm.

[0034] The two chromatography columns were filled with molecular sieves and connected in series. The chloroprene monomer entered the chromatography column through a circulation pump for adsorption and screening treatment. The detection indicators of the chloroprene monomer treated with the molecular sieve and without the molecular sieve were compared to examine the quality of the monomer.

[0035] Example 1: Take 1000g of chloroprene monomer, the molecular sieve model is 3A, the circulation pump speed is 60rpm, and the circulation is 40min.

[0036] Example 2: Take 1000g of chloroprene monomer, the molecular sieve model is 3A, the circulating pump speed is 60rpm, and the circulation is 20min.

[0037] Example 3: Take 1000g of chloroprene monomer, the molecular sieve model is 3A, the circulation pump speed is 30rpm, and the circulation is 20min.

[0038] Example 4: Take 3000g of chloroprene monomer, the molecular sieve model is 3A, the circulation pump speed is 30rpm, and the circulation is 20min.

[0039] Example 5: Take 3000g of chloroprene monomer, the molecular sieve model is 4A, the circulation pump speed is 30rpm, and the circulation is 20min.

[0040] Example 6: Take 3000g of chloroprene monomer, the molecular sieve model is 5A, the circulation pump speed is 30rpm, and the circulation is 20min.

[0041] Example 7: Take 3000g of chloroprene monomer, the molecular sieve model is 10X, the circulation pump speed is 30rpm, and the circulation is 20min.

[0042] Example 8: Take 3000g of chloroprene monomer, the molecular sieve model is 13X, the circulation pump speed is 30rpm, and the circulation is 20min.

[0043] Example 9: Take 3000g of chloroprene monomer, the molecular sieve model is ZSM-800, the circulation pump speed is 30rpm, and the circulation is 20min.

[0044] Example 10: Take 3000g of chloroprene monomer, the molecular sieve model is HY30, the circulation pump speed is 30rpm, and the circulation is 20min.

[0045] Example 11: Take 3000g of chloroprene monomer, the molecular sieve model is 5A+HY30, the circulation pump speed is 30rpm, and the circulation is 20min.

[0046] Example 12: Take 3000g of chloroprene monomer, the molecular sieve model is 5A+4A, the circulation pump speed is 30rpm, and the circulation is 20min.

[0047] Example 13: Take 3000g of chloroprene monomer, the molecular sieve model is 5A+10X, the circulation pump speed is 30rpm, and the circulation is 20min.

[0048] Example 14: Take 3000g of chloroprene monomer, the molecular sieve model is 3A+4A, the circulation pump speed is 30rpm, and the circulation is 20min.

[0049] Example 15: Take 3000g of chloroprene monomer, the molecular sieve model is 10X+HY30, the circulation pump speed is 30rpm, and the circulation is 20min.

[0050] Example 16: 3000 g of chloroprene monomer from the same batch was taken each time, the molecular sieve model was 5A+HY30, the circulating pump speed was 30 rpm, and the circulation was 20 min. The experiment was repeated until the treatment effect was significantly reduced. The experiments were numbered according to the number of times the molecular sieve was used.

[0051] Example 17: The molecular sieve used in Example 16 was regenerated and then used again. 3000 g of chloroprene monomer was taken, and the circulating pump speed was 30 rpm, and the circulation was continued for 20 min.

[0052] Comparative Example 1: 1000 g of chloroprene monomer was taken, the packing column was empty, the circulating pump speed was 60 rpm, and the circulation was carried out for 20 min.

[0053] Comparative Example 2: 1000 g of chloroprene monomer was taken, the packing column was empty, the circulating pump speed was 60 rpm, and the circulation was carried out for 40 minutes.

[0054] Comparative Example 3: 3000 g of chloroprene monomer was taken, the packing column was empty, the circulating pump speed was 30 rpm, and the circulation was carried out for 20 min.

[0055] 3. Emulsion polymerization experiment

[0056] The monomer of comparative example 3 and the chloroprene monomer treated in example 11 were subjected to emulsion polymerization experiments to investigate the polymerization process and the improvement of rubber properties.

[0057] The characterization results of chloroprene are shown in Table 2, the characterization results of chloroprene in Examples 16 and 17 are shown in Table 3, the results of the emulsion polymerization experiment are shown in Table 4, and the results of the mercaptan-adjusted rubber property test are shown in Tables 5 and 6.

[0058] Table 2: Chloroprene characterization results

[0059]

[0060] Table 3 Characterization results of chloroprene in Examples 16 and 17

[0061]

[0062] Table 4 Emulsion polymerization experimental results

[0063]

[0064] Table 5: Test results of mercaptan-adjusted rubber properties

[0065]

[0066] Table 6: Test results of sulfur-adjusted rubber properties

[0067]

[0068] As can be seen from the data in the above table, different types of molecular sieves have different adsorption and screening effects on impurities in chloroprene. Among them, 3A, 4A, 5A, and 10X have certain treatment effects on methyl vinyl ketone and 4-chloro-2-butanone, and 5A has the best effect. 10X is only effective for methyl vinyl ketone, and HY30 has a better treatment effect on dimers and inhibitors. Methyl vinyl ketone and 4-chloro-2-butanone are by-products of the chloroprene synthesis system. It is very difficult to suppress them during the production process of the synthesis tower, and the distillation system cannot be refined. Dimers and inhibitors have a great influence on the activity of chloroprene monomers, which has been troubled by chloroprene rubber production for many years and has a great influence on the performance of chloroprene rubber products. This invention has a good separation effect on the four impurities, and the treatment method is easy to implement, economical and environmentally friendly. The molecular sieve can be reused after regeneration, and the screening effect is equivalent to the initial use effect.

[0069] It is well known that different molecular sieves have different principles, such as adsorption, catalysis, ion exchange, etc., and the present invention mainly utilizes the adsorption and screening functions of molecular sieves to remove impurities in chloroprene monomer. Different molecular sieves have different adsorption and screening capabilities for impurities in chloroprene monomer. The components with molecular weights greater than the size of the pores inside the crystal can be rejected, while the components with molecular weights less than the size of the pores inside the crystal are adsorbed. Different impurities have different molecular weights and molecular structures, and the van der Waals forces of molecular sieves on them are different, resulting in differences in physical adsorption capacity, and there are strong polarity and Coulomb fields inside the crystal pores, which show stronger adsorption capacity for polar molecules and unsaturated molecules. Combining the above reasons, the monomer refining process can utilize a combination of different molecular sieves to remove different impurities.

[0070] By comparing the emulsion polymerization experimental results and the chloroprene rubber test results in the embodiment, it can be seen that after the chloroprene monomer is treated by the method of the present invention, the contents of methyl vinyl ketone, 4-chloro-2-butanone, dimer and inhibitor in the monomer are significantly reduced; by comparing the emulsion polymerization processes of the two groups of monomers, it can also be seen that the emulsion polymerization process of the chloroprene monomer after treatment is stable, the latex in the polymerization process has no gel phenomenon, the viscosity index of the chloroprene rubber obtained after the latex is dried is controllable, and the comprehensive properties such as strength, stretching, and elongation are better. Therefore, it is fully proved that the non-target components in the monomers refined by molecular sieves no longer have a negative impact on the polymerization system and rubber quality, thereby improving the rubber quality grade.

[0071] The embodiment of the present invention only compares and analyzes different types of molecular sieves and the treatment of chloroprene impurities by using different types of molecular sieves in combination, and does not optimize the best experimental conditions. According to known technologies, the screening effect is related to the type of molecular sieve, the contact time between the monomer and the molecular sieve, the contact area and other factors have a certain relationship, so the experimental scheme can be optimized through orthogonal experiments to obtain better experimental results.

[0072] The present invention only verifies that some impurities in chloroprene monomer can be removed by molecular sieve adsorption and sieving, but this method can also be considered to be applied to treat polymerized monomers in a broader sense, without being limited to the scope of the present invention.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for refining chloroprene monomer using a chloroprene monomer refining and polymerization device, characterized in that: The specific method is as follows: the chloroprene monomer is sent into the first molecular sieve tower through a circulation pump for molecular sieve screening, the chloroprene monomer after screening is continuously sent into the second molecular sieve tower for further adsorption screening, and the treated chloroprene monomer is detected and analyzed by gas chromatography; after the chloroprene monomer screening is completed, nitrogen is opened to purge the molecular sieve to ensure that the monomer is completely replaced, the discharge ports of the first molecular sieve tower and the second molecular sieve tower are closed, and the molecular sieve is protected by nitrogen; The molecular sieve is HY30 molecular sieve, 5A+HY30 or 10X+HY30; The device is a chloroprene latex polymerization kettle (1) provided with an impurity removal device, wherein the impurity removal device is a first molecular sieve tower (3) feed port connected to the outlet of a circulation pump (2), the first molecular sieve tower (3) discharge port is connected to the feed port of a second molecular sieve tower (4), the second molecular sieve tower (4) discharge port is connected to the polymerization kettle (1) feed port, and the polymerization kettle (1) discharge port is connected to the chloroprene latex tank (5).

2. The method according to claim 1, characterized in that: The top of the first molecular sieve tower (3) and the top of the second molecular sieve tower (4) are connected to nitrogen, and the bottom of the first molecular sieve tower (3) and the bottom of the second molecular sieve tower (4) are connected to a chloroprene distillation system (6).

3. The method according to claim 1, characterized in that: The specific method of nitrogen purging molecular sieve is: first use cold nitrogen for the first purge, the temperature of cold nitrogen is controlled at 0-5℃, the purge time is determined according to the gas detection index, and the exhaust gas is analyzed by gas chromatography every 1.5 hours of purge. When the chloroprene detection index is ≤5%, stop the cold nitrogen purge; after the monomer in the molecular sieve is purged clean, hot nitrogen purge is performed to remove the adsorbed impurities for regeneration, the temperature is controlled at 200-500℃, the purge time is 2-6 hours, and finally the cold nitrogen purge is cooled to 20-30℃ before it can be used again.

4. The method according to claim 1, characterized in that: The ratio between the cross-sectional diameter of the molecular sieve packing column and the column height is 1:3-10.

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