RU2177957C2 - Continuous solution copolymerization process and polymerizer for implementation thereof - Google Patents

Abstract

FIELD: polymer production. SUBSTANCE: invention, in particular, relates to ethylene-propylene or ethylene-propylene-diene copolymers. Process involves dissolution in hydrocarbon solvent of monomers and catalytic complex components: cocatalyst or cocatalysts and catalyst; feeding gas-liquid mixture and solutions of cocatalyst or cocatalysts and catalyst into bottom part of polymerizer provided with stirrer, and copolymerization of reaction mixture at stirring and elevated pressure and temperature, provided that solutions of cocatalyst or cocatalysts and catalyst are introduced over the surface of reaction mixture in coaxial, parallel, or crossed streams. Cocatalyst or cocatalysts are diluted with solvent, to which polymerizate was preliminarily added at ratio 1: (0.001-0.1), and mixing of solvent with cocatalyst or cocatalysts is performed consecutively in tubular attachment of connecting pipe for introduction of catalytic complex components under turbulent conditions. Polymerizer has covered casing with heat-exchange jacket, stirring mechanism with drive, inlet connecting pipes for gas-liquid mixture and solutions of cocatalyst or cocatalysts and catalyst, and outlet connecting pipes for recycle gas and polymerizate, inlet connecting pipe for solutions of cocatalyst or cocatalysts and catalyst being provided with coaxial tubular attachments, each of which has turbulization steps, their number coinciding with number of components added to solvent, whereas turbulization steps have at least one convergent-diffuser section. EFFECT: stabilized composition and quality of copolymers. 3 cl, 4 dwg, 2 tbl, 6 ex

Description

 The invention relates to the field of production of polymers, to the rubber industry, and in particular to a method for producing ethylene propylene or ethylene propylene diene copolymers. The invention also relates to devices for the copolymerization of these rubbers.

 A known method of continuous solution copolymerization of ethylene, propylene and 1,4-hexadiene and a device for its implementation (German patent 2413139, application. 19.03.74, US priority from 19.03.74 342423, publ. 11.09.80). The monomers are copolymerized with stirring in the presence of hydrogen and a coordination catalyst obtained by pre-mixing the catalyst components with a solvent in a rotary body mixer and continuously injecting the coordination catalyst solution into the reactor. A device for implementing this method consists of a mixer for pre-mixing and a reactor. The cylindrical mixing chamber is made with feed channels, and inside it there is a rotating mixer, capable of scrapping precipitated reaction products from the walls of the mixing chamber during rotation.

 However, the disadvantage of this method is the formation of large in size and perfect in structure crystals of the catalytic complex, which leads to a decrease in the rate of copolymerization, unevenness of its flow throughout the reactor volume and overspending of the components of the catalytic complex. The resulting crystals have high activity and are capable of intense interfacial interaction and precipitation on the walls of the mixing chamber, as a result of which it should often be cleaned. In addition, the device is structurally complex, energy-intensive and insufficient reliability of the equipment due to the sedimentation of the reaction products on the channels leaving the mixing chamber.

The closest is a method for producing ethylene-propylene copolymers (patent RU 2141871, IPC ⁶ V 01 J 19/18, C 08 F 210/16, publ. 11/27/99), including dissolving monomers, hydrogen and components of the catalytic complex in a hydrocarbon solvent, supplying a solution a gas-liquid mixture of monomers, solvent and hydrogen into the lower part of the polymerizer equipped with a stirrer, feeding solutions of the components of the catalytic complex by means of inlet fittings into the polymerization unit, copolymerization with stirring of the reaction mixture with increased yes at a temperature and temperature, while before feeding the solutions of the components of the catalytic complex to the polymerizer, which is carried out separately, the corresponding components of the catalytic complex are prepared in a solvent or solvent flow containing monomers, with turbulent mixing in the nozzles of the corresponding inlet nozzles, while the interaction of the components of the catalytic complex is carried out in a gaseous medium at the intersection or contact of dispersible streams inside the polymerizer.

 The described method does not allow to stably obtain a copolymer of ethylene with propylene, because the regenerated solvent after appropriate preparation has impurities that reduce the efficiency of separately diluted cocatalyst and catalyst. It is difficult to track the quality of the solvent in the stream, hence there is a spread in the quality of the resulting product and an increased consumption of hydrogen and catalyst.

 A continuous reactor-mixer is known, comprising a housing with inlet fittings, inside of which, along the component supply, a central cylindrical turbulizing device with an axial hole and external grooves in the form of a multi-thread and an inlet fitting is installed. Moreover, the reactor is equipped with additional nozzles for supplying the starting components located radially opposite each groove and located in front of the inlet nozzle with a replaceable nozzle with the formation of a reaction chamber between it and the turbulizing device (AS USSR 1210884, IPC B 01 J 19/20, publ. 15.02. 1986).

 The mixing reactor is designed to mix components, but is difficult to manufacture and operate.

Closest to the claimed technical solution is a polymerization unit for continuous solution copolymerization (patent RU 2141871, IPC ⁶ B 01 J 19/18, C 08 F 210/16, publ. 27.11.99), comprising a housing with a lid and a heat exchange jacket, a mixing device with a drive and technological fittings for introducing a gas-liquid mixture and components of the catalytic complex, for recirculating gas and polymerizate removal, and the fittings for separately introducing the components of the catalytic complex are equipped with tubular turbulent nozzles and placed E pipes inside the polymerizer.

 However, the presence of several pipes in the space above the reaction mass creates additional difficulties in their manufacture, installation and maintenance.

 The objective of the invention is to develop a method and device that allows continuous solution copolymerization to obtain copolymers of stable composition and quality.

 To obtain copolymers of stable composition and quality, a method of continuous solution copolymerization is proposed, comprising dissolving in a hydrocarbon solvent monomers, hydrogen and components of the catalytic complex: cocatalyst or cocatalysts and catalyst; supplying a gas-liquid mixture to the lower part of the polymerizer equipped with a mixing device; separately feeding solutions of the components of the catalytic complex into the polymerizer above the surface of the reaction mass; and copolymerizing while stirring the reaction mass at elevated pressure and temperature. In this case, the supply of solutions of the components of the catalytic complex is carried out in coaxial, or parallel, or crossed flows. Moreover, the cocatalyst or cocatalysts are diluted with a solvent into which the polymerization agent is preliminarily introduced in a ratio of 1: (0.001-0.1), and the solvent and cocatalyst or cocatalysts are mixed sequentially in a coaxial tube nozzle of the inlet of the solution for introducing the components of the catalytic complex in a turbulent mode.

 According to the proposed method, continuous solution copolymerization is carried out using a polymerization device containing a housing with a lid and a heat exchange jacket, a mixing device with a drive and technological fittings for introducing a gas-liquid mixture, solutions of the components of the catalytic complex, recirculating gas and polymerizate. Moreover, the nozzle for separate input of solutions of the components of the catalytic complex is equipped with a coaxial tubular nozzle containing inner and outer tubes, each of which has turbulization stages according to the number of components introduced into the solvent, and turbulization stages have at least one confuser-diffuser section.

 Distinctive features of the proposed method of copolymerization is that the separate supply of solutions of the components of the catalytic complex is carried out over the surface of the reaction mass in coaxial, or parallel, or crossed flows, moreover, the cocatalyst or cocatalysts are diluted with a solvent into which the polymerizate is preliminarily introduced in a ratio of 1: (0.001-0 , 1), and the mixing of the solvent, the polymerizate and the cocatalyst or cocatalysts is carried out sequentially in the coaxial tubular nozzle of the nozzle BB ode to solutions of the components of the catalytic complex in a turbulent mode.

 The hydrocarbon solvent used in the copolymerization is continuously circulated through the technological process, but despite appropriate purification, it carries the remains of monomers, carbon dioxide, sulfur, water and other impurities.

 When diluting the cocatalyst or cocatalysts with a hydrocarbon solvent having monomers and other impurities, their interaction begins with the formation of products with a network structure (gel). Next, the solution of the cocatalyst or cocatalysts with the gel formed is mixed and interacts with the catalyst solution.

The reaction of the formation of a catalytic complex proceeds quickly and the copolymerization process begins with it to form a polymer. In this case, the gel formed earlier falls into the polymer volume, which reduces the quality of the obtained product and interferes with obtaining stable characteristics of ethylene-propylene units in the product. Removing these impurities from a regenerated solvent is possible with a whole system for its purification, including hydrogenation, but this is a complex and expensive process, and given the large volumes of recycle solvent, the price of the resulting product should increase sharply. Elimination of the existing drawback is possible by feeding the polymerizate into the solvent. The polymerizate is a copolymer solution with an unwashed and unsuppressed catalytic complex in a hydrocarbon solvent
The catalytic complex completed the copolymerization process, but it still retained a number of active sites capable of interaction.

 The catalytic complex of the polymerizate, getting into the regenerated solvent, begins to interact with the monomers present in it, water, sulfur and other impurities, thereby cleaning the regenerated solvent from impurities that impede the normal conduct of the process, and the catalytic complex is completely neutralized.

 Purified from impurities, a hydrocarbon solvent with a polymerizate, when cocatalyst or cocatalysts are introduced into it, performs only the functions of a diluent. The amount of polymerizate supplied to the solvent varies depending on the content of impurities and their type in the solvent.

 Given the different density and viscosity characteristics of the hydrocarbon solvent and the polymerizate and the need for their complete and quick mixing, the process is carried out in a coaxial tubular nozzle of the nozzle for introducing solutions of the components of the catalytic complex in a turbulent mode. Since the formation of the catalytic complex in the process of interaction of the components is fast, it is necessary to distribute the supply of components through different streams. This should be done either coaxial, or parallel, or intersecting streams, but each time the streams should interact at the greatest possible distance from the nozzles or on the surface of the reaction mass.

 This is due to the fact that flows interacting near the nozzles form crystals of the catalytic complex and, ultimately, the crystals engage on the surface of the nozzle, a copolymer forms on it, and so on. The process becomes a chain. The feed nozzles of the cocatalyst or cocatalysts and catalyst are overgrown with copolymer and clogged. The process stops.

 Distinctive features of the inventive polymerization device is that the polymerization nozzle for separate injection of solutions of the components of the catalytic complex is equipped with a coaxial tube nozzle containing inner and outer tubes, each of which has turbulization stages according to the number of components introduced into the solvent, and turbulization stages have at least one confuser -diffuser section.

 The choice of the design of the tubular nozzles for the separate supply of solutions of the cocatalyst or cocatalysts and the catalyst is due to the proximity of the flows and the shortest time for the formation of the catalytic complex above or on the surface of the reaction mixture.

 In this case, the basis is the stability of the tubular nozzle, the exclusion of polymer buildup on it and the provision through the use of turbulization stages after the introduction of the next component of quick and high-quality mixing.

 This achieves a high degree of purification of the solvent from impurities, eliminating the formation of a gel in a solution of cocatalyst or cocatalysts.

 We have not found in the literature the use of a combination of features of a continuous solution solution copolymerization method and a polymerization agent for its implementation, which indicates compliance with the patentability criteria.

 In FIG. 1 shows a longitudinal section through a polymeriser.

 The polymerizer contains a housing 1 with a cover, a heat exchange jacket 2, a mixing device 3 with a drive, technological fittings for introducing a gas-liquid mixture 4, introducing solutions of the components of the catalytic complex 5, venting the recirculation gas 6 and draining the polymerizate 7. The fitting 5 is equipped with a coaxial tube nozzle 8. The fitting 7 is connected to a pipe 9 discharging the polymerizate. From the pipe 9, the polymerizate is dispensed by the metering pump 10 through the pipe 11 into the tubular nozzle 8.

 In FIG. 2 shows a section through the nozzle 5 for introducing solutions of the components of the catalytic complex. The fitting 5 is attached to the wall of the housing of the polymerization unit 1 and is equipped with a coaxial tube nozzle 8. The inner pipe 12 contains a solvent supply pipe 13, a catalyst supply pipe 14 and confuser-diffuser sections 15. The inner pipe 12 ends with a nozzle 16, the outer pipe 17 is made coaxially inner, has solvent supply pipe 18, polymerizate supply pipe 19, confuser-diffuser sections 20, cocatalyst or cocatalyst 21 supply pipe, confuser-diffuser sections 22 and ends with nozzle 23.

The position of the nozzles 16 and 23 can be coaxial (Fig. 2), parallel (Fig. 3) or non-parallel (Fig. 4). The angle of rotation of the axes of the nozzles 16 and 23 relative to the axis of the nozzle 13 is determined by the length of the nozzle inside the polymerizer and can be from 60 to 120 ^o . The polymerizer works as follows. The cooled gas-liquid mixture in certain proportions through the nozzle 4 is fed into the polymerization unit. At the same time through the nozzle 5 separately serves solutions of the components of the catalytic complex. The catalyst is introduced through the pipe 14 of the inner tube 12 of the coaxial tube nozzle (Fig. 2), and the solvent through the pipe 13. The stream, passing through the turbulization section 15, equalizes the concentration of the catalyst by volume and then passes through the nozzle 16 into the gaseous medium above the surface of the reaction mixture.

 The cocatalyst or cocatalysts are fed through the pipe 21 of the outer pipe 17 of the coaxial tubular nozzle 8. The solvent through the pipe 18 is introduced into the inner cavity of the outer pipe 17 located coaxially to the inner pipe 12. The polymerizate is introduced through the pipe 19 and is evenly distributed throughout the solvent when moving through the pipe stage 20 .

 Turbulization is necessary due to the limited mixing time of liquids with different viscosities and densities.

 The catalytic complex of the polymerizate evenly distributed in the solvent, having a certain number of active centers, interacts with the monomeric and other impurities of the solvent, purifying it. The cocatalyst or cocatalysts are introduced into the purified solvent through the pipe 21, which are quickly and uniformly mixed into the stream in the steps of turbulization 22.

 Due to the absence of impurities in the solvent, dilution with it of the cocatalyst or cocatalysts does not cause gel formation.

 Nozzles 16 and 23 are located coaxially, providing an initial separate supply of flows near their mouth. Thus, the mouths of nozzles 16 and 23 remain moistened with one of the components of the catalytic complex, which excludes the formation of nascent crystals of the catalytic complex on them and the subsequent copolymerization of monomers on them, which ultimately leads to clogging of the nozzles by the copolymer. Nozzles 16 and 23 can be parallel to each other or non-parallel, but the mixing of the components of the catalytic complex should be carried out either above the surface or on the surface of the reaction mass.

 The resulting catalytic complex is evenly distributed over the volume of the reaction mass and the copolymerization process is carried out continuously. The resulting copolymer in the form of a solution (polymerizate) is discharged through the nozzle 7 from the polymerization unit. From the outlet pipe 9 by the pump 10 (Fig. 1), the polymerizate is fed into the pipe 19 of the coaxial tubular nozzle 8 of the nozzle 5 (Fig. 2).

 All of the above is confirmed by the following examples.

Example 1
A gas-liquid mixture with a volume of 2500 ± 15 kg / h, cooled to a temperature of minus 10 ^o C, is introduced into a polymerizer with a volume of 16.6 m ³ at a speed of rotation of the mixing device of 120 rpm The gas-liquid mixture contains (wt. Shares):
Liquid propylene (GOST 25043-87) - 0.15
Ethylene (GOST 25070-87) - 0.1
Purified hydrogen (GOST 3022-80) - 0.05
Recirculation gas (ethylene, propylene, hydrogen) - 0.7
Solutions of components of the catalytic complex are introduced through a coaxial tube nozzle of the polymerization nozzle.

Through the inner tube with a diameter of 10 mm of the tubular nozzle, the VOC1 ₃ catalyst (TU 48-4-533-90) - 1.5 ± 0.1 kg / h in fresh nefras (TU 38.1011 228-90) - 50 kg / h. Through an outer pipe with a diameter of 80 mm, A1 (C ₂ H ₅ ) C1 cocatalyst - 15 ± 0.2 kg / h in recirculated nefras (TU 38.1011 228-90) - 5000 kg / h. In the nephras, introduced into the outer tube, add the polymerizate taken from the bypass pipe of the polymerizer in an amount of 250 kg / h, which is 0.05 wt. parts relative to the supplied nephras. Its input is provided by the pump NSh-06.

 In the coaxial tubular nozzle of the input port of the components of the catalytic complex, each pipe is equipped with turbulization stages, each of which has two confuser-diffuser sections. An exception is the stage of turbulization after entering the polymerizate into the nephras - 3 sections.

 The turbulization stages of the tubular nozzle are presented in table 1.

The coaxial tube nozzle extends into the internal volume of the polymerization unit, and the nozzles of the tubes are coaxially and at an angle of 90 ^° to the axis of the component inlet and 0.45 m from the surface of the reaction mass. The nozzle mouths are in one line and have a slight narrowing (up to 10 -15% of the area of each pipe). The flows of the catalyst and cocatalyst in nefras, flowing coaxially from the mouth of the nozzles of the tubular nozzle, do not contact each other at the beginning, and then some of them come into contact in the gas phase above the surface of the reaction mass to form a catalytic complex, and the other, getting on the surface of the reaction mass, is near each other is mixed in the liquid phase.

The pressure inside the polymerization apparatus is 0.40 MPa, the temperature of the reaction mixture in the polymerization apparatus is maintained within the range of 35-45 ^{° C.} due to heat removal through the jacket and evaporation of liquid monomers.

 When feeding nefras for the solvent of the catalyst and cocatalyst under a pressure of 0.6 MPa, the issues of achieving a speed of more than 0.25 m / s are structurally solved, which ensures the creation of a turbulent flow and the mixing intensity of each input component, and the flow of the cocatalyst solution moves at a speed of at least twice as much, which provides intensive and rapid mixing of the solvent and the polymerizate and the process of binding monomers, water and other impurities in the solvent.

 The discharge of the polymerizate (copolymer solution) is carried out through the fitting. Then the polymerizate is fed to the isolation step. The characteristics of the finished copolymer (SKEP) are shown in table 2, experiment 1.

Example 2 (prototype)
The conditions of the experiment as described in example 1, but the supply of the polymerizate to nefras, going to dilute the cocatalyst, is absent. The characteristics of the finished copolymer are shown in table 2, experiment 2.

Example 3
The conditions of the experiment are shown in example 1.

 A liquid monomer, ethylidene norbornene, in the amount of 55 kg per ton of finished ternary copolymer (SKEPT) is additionally introduced into the gas-liquid mixture. The experimental results are shown in table 2, experiment 3.

Example 4
The experimental conditions as described in example 1. The tubular nozzle of the nozzle is made coaxial, and the nozzles for supplying the solutions of cocatalyst and catalyst are spaced apart, the axis of the nozzle for feeding the catalyst is located relative to the axis of the tubular nozzle at 90 ^o , and the axis of the nozzle for feeding the cocatalyst is under 105 ^o , i.e. . the axis of the nozzles are not parallel, which ensures the displacement of the flows relative to each other and their mixing is carried out on the surface of the reaction mass
The results of the experiment are shown in table 2, experiment 4.

Example 5
Conditions as in example 1. As cocatalysts, use A1 (C ₂ H ₅ ) ₂ C1 and ACO (cobalt act TU 6-09-17-236-93) in a ratio of 10: 0.5. In this case, the second ACO cocatalyst is supplied for dissolution in nephras into the inner tube of the tubular nozzle together with the VOC1 catalyst in a ratio of 1: 0.5. The results of the experiment are shown in table 2, experiment 5.

Example 6
The conditions as in example 3. The quantity of polymerisate fed varies: 0.001, 0.005, 0.01, 0.1, 0.13 parts by weight of the dry copolymer relative to the solvent fed, taken as 1, experiments 6-10, respectively.

The recycled solvent contains about an average of C ₃ 0.15 - 0.2%, ENB 0.05%, water 0.002%, sulfur 0.0002% and lower, and the concentration of the catalytic complex in the polymerizate is 0.2%, although the content it can vary from 0.03 to 2.0% depending on the consumption of components and the depth of the copolymerization process. The characteristics of the obtained copolymer are shown in Table 2. It can be seen from the above examples that the preparation of the copolymer of the required quality (TU 2294-022-05766801-94) and the stability of the copolymerization process are determined by introducing the polymerizate into the hydrocarbon solvent used to dilute the cocatalyst, its ratio ranges from 0.001 -0.1 to the solvent and it is determined both by the amount of impurities contained in it and by the amount of residues of the catalytic complex supplied with the polymerizate. Although it is not possible to get rid of the presence of gel in the copolymer, its amount does not interfere with processing and the operational properties of the copolymer are improved. In addition, a necessary condition for the stability of the process of continuous copolymerization is the creation of conditions for the separate supply of solutions of the components of the catalytic complex, in which they are mixed with the formation of the catalytic complex either in the gaseous medium and on the surface of the reaction mass or only on the surface of the reaction mass.

 The polymerizer is easy to upgrade and maintain, stable in operation.

Claims (2)

 1. The method of continuous solution copolymerization, comprising dissolving in a hydrocarbon solvent monomers, hydrogen and components of the catalytic complex: cocatalyst or cocatalysts and catalyst; feeding a gas-liquid mixture to the lower part of the polymerization device equipped with a mixing device, separately feeding solutions of the components of the catalyst complex into the polymerizer above the surface of the reaction mass and copolymerizing while mixing the reaction mass at elevated pressure and temperature, characterized in that the feeding of the solutions of the components of the catalyst complex is carried out in coaxial or parallel or cross flows, wherein the cocatalyst or cocatalysts are diluted with a solvent in which dvaritelno administered polymer in a ratio of 1: (0.001-0.1), and solvent mixture, the polymer and the cocatalyst or co-catalysts is carried out sequentially in a coaxial tubular nozzle fitting solutions input component of the catalyst complex in the turbulent regime.  2. The polymerizer for continuous solution copolymerization, comprising a housing with a lid and a heat exchange jacket, a mixing device with a drive and technological fittings for introducing a gas-liquid mixture and solutions of the components of the catalytic complex, exhaust gas recirculation and polymerizate, characterized in that the polymerization nozzle for separate input solutions of components the catalytic complex is equipped with a coaxial tube nozzle containing inner and outer tubes, each of which has stages bulizatsii in the number of components administered to the solvent, and the turbulence level are not less than a confuser-diffuser section.

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