RU2155195C1 - Butyl rubber production process - Google Patents

Abstract

FIELD: rubber industry. SUBSTANCE: in a butyl rubber production process involving isobutylene-isoprene copolymerization in solution or dispersion in hydrocarbon solvent in presence of Friedel-Crafts catalyst also including preparation and deactivation of catalyst, stabilization of polymer with antioxidant, water degassing of rubber, processing of return products, preparation of charge mixture, and drying of rubber, catalyst solution is introduced into reaction zone by two streams. First stream containing 50- 85% of total catalyst intake is fed into lower part of reaction zone and stabilized at specified level. The second stream, fed into upper part of reaction zone, contains 15 to 50% of the total catalyst intake in dependence on Mooney viscosity of rubber, this stream being directed at angle 30-65 deg to radial cross-section of reactor. Feed rate of cat solution is advantageously maintained between 0.5 and 5.0 m/s. EFFECT: increased reactor run and improved quality of rubber and performance characteristics of rubber production. 2 cl, 1 dwg, 5 tbl, 14 ex

Description

 The invention relates to the field of synthetic rubbers, in particular butyl rubber, and can be used in the petrochemical industry.

A known method of producing butyl rubber by low-temperature copolymerization of isobutylene with isoprene in a hydrocarbon solvent or diluent in the presence of a Friedel-Crafts catalyst, for example aluminum chloride dissolved in methyl chloride with a concentration of about 0.1 wt.% At a temperature of minus 90 ^o C supplied to the lower part of the reactor for polymerization, which also introduces a hydrocarbon mixture containing 17-20% isobutylene, 0.5-0.7% isoprene and a diluent or hydrocarbon solvent and mixed with a catalyst solution axial pump. [The album of technological schemes of the main industries of the synthetic rubber industry. P.A. Kirpichnikov, V.V. Berestnev, L.M. Popova, L .: Chemistry, 1986, p. 145-147].

 The disadvantage of this method is the inhomogeneous distribution of the catalyst in the reaction volume of the reactor, which contributes to the sticking on the inner surface of the reactor, the spread of plastoelastic properties of rubber, inefficient use of the catalyst, short polymerization cycles.

Closest to the claimed method for producing butyl rubber is a method consisting in copolymerizing isobutylene with isoprene in solution or in a dispersion in a hydrocarbon solvent or diluent in the presence of a Friedel-Crafts catalyst, introduced into the reaction zone in a hydrocarbon solvent or diluent, which also includes preparation, deactivation of the catalyst, stabilization of the polymer with an antioxidant, water degassing of rubber, processing of return products and preparation of the charge, and drying of the rubber, moreover, kata izator fed to the bottom of the reactor through three input centrifugal pump under a pressure of 8 atm at a temperature of minus 95 ^o C with a concentration of 0.05-0.10 wt. %, the charge is also sent to the lower part of the reactor. [Basics of petrochemical synthesis technology. Gostoptekhizdat. M., 1960, p. 656-659].

 The disadvantage of this method is the insufficient efficiency of controlling the copolymerization process due to the complexity of taking into account the delay in the system, the presence of high concentrations of catalyst in various places of the reaction zone, caused by poor distribution of the catalyst due to low flow rates, a large spread of indicators that determine the quality of the rubber. In particular, the standard deviation of the Mooney rubber viscosity reaches 8.5-10.0 units, the catalyst consumption varies between 0.1-0.5 kg / t of rubber even with a constant quality of raw materials.

 The heterogeneity of the distribution of the catalyst in the reaction volume promotes the formation of conglomerates of catalyst and rubber, clogging of the outlet pipes from the reactor, which leads to a change in the run length of the reactors from 25 to 60 hours during copolymerization in a diluent and from 270 to 560 hours during copolymerization in a hydrocarbon solvent.

 The objective of the proposed method for producing butyl rubber is to increase the mileage of reactors, improving the quality of rubber and improving technical and economic indicators of production.

 This problem is solved in that in the known method for producing butyl rubber by copolymerization of isobutylene with isoprene in solution or in a dispersion in a hydrocarbon solvent or diluent in the presence of a Friedel-Crafts catalyst, introduced into the reaction zone in a hydrocarbon solvent or diluent, which also includes preparation, deactivation of the catalyst, stabilization polymer antioxidant, water degassing of rubber, processing of return products and preparation of the mixture and drying of the rubber, a catalyst solution is introduced the reaction zone in two streams, (50-85)% of the total catalyst consumption is directed to the lower part of the reaction zone in the first part and stabilized at a predetermined level, (15-50)% of the total catalyst consumption is fed to the upper part of the reaction zone in the second depending on the Mooney viscosity of the rubber, the catalyst solution being supplied through a second stream at an angle of 30-65 degrees to the radial section of the reactor.

 The speed of the catalyst solution introduced into the reaction zone is maintained, preferably, in the range of 0.5-5.0 m / s.

 In contrast to the known method, in the proposed method for producing butyl rubber by introducing the catalyst solution in two streams into two zones, the Mooney viscosity dispersion is reduced in rubber, especially when the catalyst solution is fed into the upper reaction zone at an angle of 30-65 degrees to the radial section of the reactor. Due to this, the dispersion of the Mooney viscosity is reduced to 3-5 units, which is especially characteristic when using high rates of catalyst injection.

 If in existing plants the feed rate of the catalyst solution reaches 0.035-0.075 m / s, then the use of catalyst injection rates in the range of 0.5-5.0 m / s not only helps to increase the uniformity of rubber, but also reduces the cost of the catalyst and increases the conversion of monomers and increased mileage of reactors. At a high speed of the process of copolymerization of isobutylene with isoprene, the uniformity of the distribution of the catalyst in the reaction volume reaches a significant value.

 By introducing (50-85)% of the total catalyst consumption into the lower reaction zone, with the required purity of the feed, almost 65-75% conversion of the monomers is achieved. Perturbations on the part of the feedstock and the conditions of heat removal through the metal wall to evaporating ethylene require adjustment at the final stage of the copolymerization process. The necessary Mooney rubber viscosity and performance are provided by introducing a catalyst into the second to upper reaction zone. The remaining (15-50)% of the total catalyst consumption allows us to obtain the desired result — to achieve not only the required Mooney rubber value, but also significantly increase the reactor run time.

 The inventive method for producing butyl rubber is carried out according to the scheme shown in the drawing.

 The scheme contains: lines 1,4,5,6,12,13,14,15,16,22,24,25 and 28 for supplying a hydrocarbon charge, a catalyst for the first stream into the lower reaction zone, a catalyst for a second stream in the upper reaction zone ethylene to the evaporator, acute water vapor for degassing rubber, circulating water, an anti-agglomerator suspension, an aqueous solution of alkali, methanol, rubber dispersion for final degassing, an antioxidant suspension at the pump inlet and in line with circulating water and acute water vapor to the ejector, respectively; lines 8,9,17,19,20,22,26,29,30 and 32 - output of ethylene vapor to the compressor, dispersion of rubber or solution for degassing, vapor degassing to condensation, condensate to separation, rubber dispersion to the pump inlet, dispersion rubber for final degassing, vapor degassing for the ejector, vapor degassing for the first stage of degassing, dispersion of rubber at the pump inlet and dispersion of rubber for concentration, crushing water from the crumbs and drying the rubber crumbs; 2 - reactor, 3 - stirrer, 7 - ethylene evaporator, 10 - crumb binder, 11 - degasser, 18 - condenser, 21.31 - pumps, 23 - vacuum or low pressure degasser, 27 - ejector.

 The method of copolymerization of isobutylene with isoprene is carried out, for example, as follows.

 A hydrocarbon charge, which is a mixture of isobutylene, isoprene and methyl chloride isobutylene fraction containing 20-25 wt.% Isobutylene and 0.6-0.8 wt. % isoprene or a mixture of isobutylene, isoprene and isopentanisobutylene fraction and methyl chloride, ethyl chloride or methylene chloride with a content of 45-60 wt. % of isobutylene and 1.2-2.5 wt.% of isoprene are sent via line 1 to reactor 2 with stirrer 3, where Friedel-Crafts catalyst solution, for example, aluminum chloride in a solution of methyl chloride or ethyl aluminum sesquichloride in a solution of isopentane, is introduced through lines 4 and 5.

 (50-85)% of the total catalyst consumption in line 4 is introduced into the lower reaction zone in reactor 2, (15-50)% of the total catalyst consumption with catalyst concentration is introduced into the upper reaction zone in line 5, preferably 0.08- 0.12 wt. %, and the catalyst solution in the upper reaction zone is fed through line 5 at an angle of 30-65 degrees to the radial section of the reactor. The speed of the catalyst solution introduced into the reaction zone is maintained, preferably, 0.5-5.0 m / s.

 In contrast to the known method, when the catalyst is introduced into only one zone, the introduction of the catalyst in two streams, the first to the lower part of the reaction zone, the second to the upper part of the reaction zone at an angle of 30-65 degrees allows not only to achieve a more uniform distribution of the catalyst but also to reduce the costs of the catalyst and raw materials for production, as well as significantly increase the mileage of the reactors before washing them due to less sticking of polymer particles and catalyst on the surface of the reactor and the tubes of the ethylene evaporator at a lower rate of clogging of the outlet pipe from the reactor. The temperature in the reactor 2 is maintained due to the evaporation of ethylene supplied through line 6 to the evaporator 7. Ethylene vapors through line 8 are led to a compressor (not shown in the diagram), and the resulting butyl rubber product in the form of a dispersion or solution is sent through line 9 to the crumb binder 10 degasser 11. In the crumbling agent 10 line 12 serves sharp water vapor and line 13 - circulating water. A suspension of the anti-agglomerator is sent along line 14, and an aqueous alkali solution is sent along line 15. When copolymerization of monomers in a diluent-methyl chloride medium is carried out, steam and circulating water supplied through lines 12 and 13 are used as a deactivator; when copolymerization of monomers in isopentane is used, for example, methanol supplied through line 16.

 The hydrocarbons distilled during degassing with a small amount of water vapor are removed from the degasser 11 through line 17 to a condenser 18 and then through line 19 for processing (not shown in the diagram).

 The dispersion of rubber in water from the degasser 11 is withdrawn through line 20 by pump 21 and then through line 22 to a vacuum degasser (or degasser under slight overpressure) 23. A suspension of the antioxidant is fed through line 24 to the pump inlet 21, and, if necessary, via line 25 to the circulation water line 13. Vapors from the degasser 23 are sent via line 26 to the ejector 27, into which working steam is supplied via line 28, and then, via line 29, they are led to the degasser 11. During solution polymerization of the monomers, the degassing vapors discharged via line 26 are sent on condensation (on with heme not shown). The dispersion of rubber in water, filled with an antioxidant, is sent from the degasser 23 through line 30 to the pump 31 and then along line 32 to concentration, the water is squeezed out of the rubber crumb and dried in worm-squeezed drying units (not shown in the diagram). After condensation, drying and compression in the form of condensate or partially in the form of vapors, hydrocarbon degassing vapors are subjected to separation in distillation columns (not shown in the diagram) and withdrawn in the form of a pure hydrocarbon solvent or hydrocarbon diluent to prepare a catalyst, or isobutylene and return isobutylene methyl chloride fraction or isobutylene isopentane fractions for the preparation of the mixture.

 The method is illustrated by the following examples.

 Example 1 (control).

Butyl rubber is obtained by a known method by copolymerization of isobutylene with isoprene in a reactor with a volume of 16 m ³ with a paddle type mixer. In the reactor serves 15 t / h of the mixture of the following composition, wt.%: Isobutylene 21.5; isoprene 0.6; methyl chloride 77.9. The temperature of the mixture is minus 95 ^o C, the temperature of the catalyst solution minus 90 ^o C. As a catalyst use a solution of aluminum chloride in methyl chloride concentration of 0.1 wt.%. The catalyst solution is introduced into the lower reaction zone at a speed of 0.04 m / s, with a pressure in the pump discharge line of 0.8 MPa. The average copolymerization temperature minus 92.0 ^o C. the charge is also served in the lower part of the reactor.

Key process indicators:
monomer conversion,% - 75.2
dry solids,% - 16.6
catalyst consumption, kg / t butyl rubber - 0.3
mileage of the reactor, h - 46.7
rubber production per cycle, t - 116.3
Mooney rubber viscosity - 50.9
the range of the viscosity of the Mooney rubber is 8.0
unsaturation, mol.% - 1,6
Examples 2-4.

Butyl rubber is obtained by the proposed method by copolymerization of isobutylene with isoprene in a reactor with a volume of 16 m ³ with a paddle type mixer. 15 t / h of a mixture of a composition similar to that described in Example 1 are fed into the reactor. The temperature of the mixture is minus 95 ^o C, of the catalyst solution minus 90 ^o C. Aluminum chloride in methyl chloride with a concentration of 0.1 wt.% Is used as a catalyst. % The catalyst solution is introduced in two streams, the first to the lower reaction zone under the lower stirrer blade at a height of 1.7 m from the bottom of the reactor, the second to the upper reaction zone, 2.0 m above the first stream. The amount of catalyst solution is introduced in the amount (50-85)% of the total flow rate in the radial section, (15-50)% of the total flow rate of the catalyst solution at an angle of 45 ^o C to the radial section of the reactor is introduced into the upper reaction zone, and the flow rate of the catalyst is stabilized in the lower zone at a predetermined level, in the upper reaction zone, the flow rate of the catalyst changes yayut depending on the Mooney viscosity of the rubber. The rate of introduction of the catalyst solution is 0.035-0.080 m / s. The pressure in the discharge line of the pump is 0.8 MPa. The mixture is introduced into the lower zone of the reactor.

 Key process indicators, see table. 1.

Examples 5-7
Butyl rubber is prepared according to the proposed method in methyl chloride environment. The composition of the mixture, the temperature of the mixture and the catalyst solution are the same as in example 1. The concentration of the catalyst solution of aluminum chloride in methyl chloride is 0.1 wt.%. The pressure in the discharge line of the pump at a catalyst feed of 2.0 MPa. The catalyst solution is introduced in two streams, in the lower reaction zone and in the upper reaction zone at different angles to the radial section. The feed rate of the catalyst solution is 1.5 m / s. The reactor is the same as in Example 1. An equal amount of catalyst is introduced into each zone.

 Key process indicators (see table. 2).

 Example 8-10

 Butyl rubber is prepared according to the proposed method in a manner analogous to the conditions given in Examples 5-7, only the rate of introduction of the catalyst solution into both reaction zones is changed.

 Key process indicators (see table. 3).

 Examples 11-12.

 Butyl rubber is obtained by a known method (example 11) and by the proposed method (example 12) in a solution of isopentane.

 In an industrial reactor equipped with an axial pump, 11 t / h of a hydrocarbon charge containing 55 wt.% Isobutylene are fed; 1.65 wt.% Isoprene; 8 wt. % ethyl chloride and 35.35 wt.% isopentane. In one case, 30 l / h of a solution of ethyl aluminum sesquichloride in isopentane with a degree of protonation of 50% with water is fed into the lower zone of the reactor (Example 11). The concentration of the catalyst in the isopentane solution was 8.3 g / L. In another case (Example 12), 20 l / h of a solution of ethyl aluminum sesquichloride in isopentane of the same degree of protonation and concentration are fed into the lower zone of the reactor, and 10 l / h of the same solution of ethyl aluminum sesquichloride are introduced into the upper reaction zone.

The copolymerization of isobutylene with isoprene in both cases is carried out at an average temperature of minus 77 ^o C. The reaction is stopped with methanol, then the polymer solution is supplied for degassing and stabilization, the rubber crumb is dried and sent for briquetting and packaging.

 Key process indicators (see table. 4).

Examples 13-14. Butyl rubber is prepared according to the known (example 13) and proposed methods (example 14) in a methyl chloride medium in a reactor with a volume of 20 m ³ with a paddle mixer.

The catalyst is a solution of aluminum chloride in methyl chloride with a concentration of 0.12 wt. % The composition of the mixture, wt.%: Isobutylene - 22.3; isoprene 0.6 and methyl chloride 77.1. The temperature of the mixture is minus 95 ^o C, the temperature of the catalyst solution minus 90 ^o C. In example 13, the catalyst solution is introduced into the lower reaction zone depending on the temperature at the outlet of the products from the reactor, in example 14, the catalyst solution in the lower reaction zone is stabilized at 50% of the average flow rate into the reactor, and the remaining amount of catalyst is fed to the upper reaction zone, which is adjusted depending on the Mooney rubber viscosity at the outlet of the first rubber degassing stage.

 Key process indicators (see table. 5).

 As can be seen from the examples, the introduction of the proposed method for producing butyl rubber can improve the technical and economic efficiency of the process, reduces catalyst consumption by 12.5-40.0%, increases the conversion of monomers by 3.3-5.9% and increases the duration of the polymerization cycles.

Claims (2)

1. A method of producing butyl rubber by copolymerization of isobutylene with isoprene in a hydrocarbon solvent or methyl chloride diluent in the presence of a Friedel-Crafts catalyst introduced into the reaction zone in a hydrocarbon solvent or diluent, which also includes preparation of the catalyst, catalyst deactivation, polymer stabilization with an antioxidant, rubber rubber degassing, processing return products and the preparation of the mixture and drying of the rubber, characterized in that the catalyst solution is introduced into the reaction zone Well, in two streams, according to the first - 50 - 85% of the total catalyst consumption is directed to the lower part of the reaction zone and stabilized at a predetermined level, and 15 - 50% of the total catalyst consumption is fed to the upper part of the reaction zone, depending on the viscosity Mooney rubber, and the catalyst solution in the second stream serves at an angle of 30 - 65 ^o to the radial section of the reactor.  2. The method according to claim 1, characterized in that the speed of the catalyst introduced into the reaction zone is preferably maintained between 0.5 and 5.0 m / s.

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