RU2415154C1 - Butyl rubber synthesis method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention pertains to a method of producing butyl rubber. The method involves preparation of a mixture from isobutylene, isoprene and returned products, copolymerisation of the mixture in a medium of a diluent - methyl chloride in several reactors working in parallel in the presence of an aluminium chloride catalyst, involving degassing the rubber, processing non-polymerised monomers and the diluent - methyl chloride, averaging, drying the ready polymer on extrusion-type machines and briquetting. The copolymerisation process is carried out in the presence of two catalyst modifiers, one of which is water and the second is selected from a group of organic substances with general formula C₆H₅-X, where X is halogen or a radical with formula -C_nH_2n+1-Hal, where n=1-2. Molar ratio AlCl₃: H₂O is kept in the range 1:0.5-20, and molar ratio AlCl₃: C₆H₅-X is kept in the range 1:50-350.

EFFECT: obtaining butyl rubber which is used in riding chambers and shaper-vulcaniser chambers.

2 cl, 21 ex, 1 tbl, 1 dwg

Description

The invention relates to the production of rubbers, in particular, to a method for producing butyl rubber, which is used in the manufacture of driving chambers and chambers of formatting vulcanizers. Butal rubber is obtained by low-temperature suspension copolymerization of isobutylene with a small amount of isoprene in a chloromethyl medium on a cationic catalyst - aluminum chloride.

A known method of producing butyl rubber, which consists in the copolymerization of isobutylene with isoprene in a hydrocarbon solvent or diluent in the presence of a Friedel-Crafts catalyst, for example aluminum trichloride dissolved in chloromethyl with a concentration of about 0.1% wt. or lower, at a temperature of minus 90 ° С supplied to the polymerization reactor, where a hydrocarbon mixture containing isobutylene, isoprene and diluent is also introduced (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.145-151). The main disadvantage of this method is the low activity of the catalyst, which leads to its increased costs and due to this to short cycles of polymerization. The increase in catalyst activity is possible due to the addition of water or anhydrous hydrogen chloride to the aluminum chloride solution (Patent EP No. 0279456, IPC C 08 F 2/06, publ. 08.24.1988; US Patent No. 5169914, IPC C 08 F 10/00, publ. . 08/12/1992; US Patent No. 5506316, IPC C 08 F 10/00, publ. 09.04.1996). However, it is not possible to establish a clear dosage of these components due to the fact that in parallel with the formation of the active catalytic complex of aluminum chloride with the cationogen, a hydrolysis reaction proceeds with the formation of an uncontrolled amount of hydrogen chloride.

Closest to the claimed is a polymerization method capable of cationically polymerizing monomers (RF Patent No. 2280651, IPC C 08 F 210/12, publ. July 27, 2006). The method includes reacting isoolefin and diene monomers in a polar solvent (including the copolymerization of isobutylene with isoprene), a Lewis acid and a modifier; the modifier corresponds to the formula:

where X is halogen, and R ₁ , R ₂ , R ₃ are alkyl and alkenyl radicals of different lengths.

Depending on the structure of the radicals in the modifier, the initial polymerization rate decreases to a greater or lesser extent compared to the process in which water or HCI is used as a modifier. At the same time, the conversion of isobutylene decreases during the passage of the reaction mass through the reactor, which is the main disadvantage of this method.

The objective of the proposed method is to obtain a stably active catalytic complex of aluminum chloride in the process of producing butyl rubber, reducing the initial copolymerization reaction rate necessary for efficient heat removal, without reducing the conversion of isobutylene during residence in the reactor, increasing the concentration of isobutylene in the charge without reducing the duration of the runs of polymerizers and in the ultimate increase in rubber production.

The problem is solved by producing butyl rubber in a manner that includes the preparation of a mixture of isobutylene, isoprene and return products, copolymerization of the mixture in a diluent — methyl chloride in several reactors in parallel in the presence of an aluminum chloride catalyst, rubber degassing, processing of unpolymerized monomers and a diluent — methyl chloride, averaging, the finished polymer on extrusion machines and its briquetting, while copolymerization is carried out in the presence of two modif Katori catalyst - aluminum chloride, one of which - water, and the other is selected from the group consisting of organic compounds of the general formula C ₆ H ₅ -X, where X - a halogen or a radical of the formula C _n H _{2n + 1} Hal, where n = 1- 2. In this case, the molar ratio of AlCl ₃ : H _{2 is} maintained within 1: 0.5 ÷ 20, the molar ratio of AlCl ₃ : C ₆ H ₅ -X is within 1: 50 ÷ 350. Both modifiers are dosed either into the mixture or into the catalyst solution, or one of them into the mixture, and the other into the catalyst solution.

In contrast to the known methods, the proposed method uses two catalyst modifiers to obtain a stably active catalytic complex, one of which, water, increases the number of reaction centers, and the second modifier with the general formula C ₆ H ₅ -X reduces the initial polymerization rate, thereby improving the possibility of heat removal in the initial period of polymerization and preventing the formation of a low molecular weight polymer, while the number of active sites of the catalyst is not reduced. This combined use of aluminum chloride modifiers is being proposed for the first time.

The advantage of the proposed method is that without additional energy costs there is an increase in rubber production from one reactor per run due to the possibility of increasing the concentration of isobutylene in the charge.

The proposed method for producing butyl rubber is carried out, for example, according to the scheme below as follows (see drawing).

The mixture for producing butyl rubber is prepared by mixing isobutylene, isoprene and the return isobutylene chloromethyl fraction (ICP) in the pipeline and contains 25-35 wt.% Isobutylene, 0.5-0.7 wt.% Isoprene, the rest is chloromethyl. Isobutylene is fed to the mixing through the tank 1 through line 2, isoprene is fed into the mixing through the tank through line 4, the recycling ICP through the tank 5 - through line 6. The mixture through line 7 is sent to the reactor with stirrer 8, where catalyst solution is introduced through line 9, for example aluminum trichloride in a solution of methyl chloride.

The temperature in the reactor is maintained due to the evaporation of ethylene supplied to the bundles of the built-in heat exchanger. The resulting suspension of butyl rubber in chloromethyl is sent along line 10 through crumb former 11 to degasser 12, where sharp steam and circulating water are supplied through lines 13 and 14. An antiagglomerator — calcium stearate — is introduced into the circulating water through line 15 to stabilize the rubber crumb. The dispersion of rubber in water from the degasser 12 is withdrawn through line 16 to a vacuum degasser 17. A suspension of antioxidant in water is introduced into line 16 through line 18 to stabilize the polymer from oxidative degradation. The dispersion of rubber in water after the degasser 17 through line 19 is averaged into apparatus 20, then through line 21 to dry into an extrusion apparatus 22 and through line 23 for briquetting.

The hydrocarbons distilled during degassing with a small amount of water vapor from degassers 12 and 17 go through line 24 to the recovery product recovery system. When carrying out the process in accordance with the claimed technical solution, catalyst modifiers are metered into the charge supply line to the polymerizers or to the supply line of the catalyst solution to the polymerizers.

The method is illustrated by the following examples.

Example 1 (by analogy).

Isobutylene in the amount of 17 t / h is fed to the preparation of the charge, isoprene is fed to the preparation of the charge in the amount of 0.51 t / h, IHP is fed to the preparation of the charge in the amount of 48 t / h with isobutylene content up to 5 wt.%, While the concentration of isobutylene in the charge is 29.6 wt.%. The mixture is fed in parallel to five reactors at a temperature of minus 90 - minus 94 ° C, and a solution of aluminum chloride in chloromethyl with a concentration of 0.06 wt.% Is also fed there. Water is dispensed into the catalyst feed line into the polymerizers in an amount of 250 ml / h. On average, 600 l of catalyst solution is supplied per hour to each reactor with a temperature of minus 90 - minus 94 ° C (3000 l of catalyst solution for 5 polymerizers). The rubber crumb in the first stage of degassing is charged with a suspension of calcium stearate in water at a rate of 0.8-1.0 wt.% Per polymer, and before entering into a vacuum degasser with a mixture of antioxidants Agidol-2 and Irganox-1010 at a rate of 0.05-0.15 wt.% Per polymer. Further, the rubber goes for drying and briquetting. The hydrocarbons distilled during degassing pass through a system of condensers and separators, then they are compressed, dried and rectified, after which the isobutylene chloromethyl fraction is fed to the charge.

Example 2 (prototype).

The method is carried out as in example 1, except that a chlorinated isobutylene dimer (2,2,4,4,4-tetramethylpentane chloride) is dosed in the amount of 45 g / h in the form of a solution in chloromethyl or individually in the line of the catalyst solution.

Example 3

The method is carried out as in example 1, except that 270 g of water are dosed into the catalyst solution, and 16.5 g of benzyl chloride are dosed into the charge supply line, while the molar ratio AlCl ₃ : H ₂ O is 1: 1, and the molar ratio All ₃ : C ₆ H ₅ CH ₂ —Cl is 1: 100.

Examples 4-8.

The method is carried out as in example 3, except that 1350 g of water is metered into the catalyst solution (AlCl ₃ : H ₂ O ratio of 1: 0.2) (example 4); 540 g (ratio AlCl ₃ : H ₂ O - 1: 0.5) (example 5); 27 g (AlCl ₃ : H ₂ O ratio - 1:10) (Example 6); 13.5 g (AlCl ₃ : H ₂ O ratio - 1:20) (Example 7); 10.8 g (AlCl ₃ : H ₂ O ratio - 1:25) (Example 8).

Examples 9-13.

The method is carried out as in example 3, except that benzyl chloride in the amount of 66 g / h is dosed into the charge line (AlCl ₃ ratio: C ₆ H ₅ CH ₂ -Cl - 1:25) (example 9); 33 g / h (AlCl ₃ : C ₆ H ₅ CH ₂ -Cl -1: 50 ratio) (Example 10); 8.25 g (AlCl ₃ : C ₆ H ₅ CH ₂ -Cl - 1: 200 ratio) (Example 11); 5.5 g (AlCl ₃ : C ₆ H ₅ CH ₂ -Cl -1: 300 ratio) (Example 12); 4.12 g (AlCl ₃ : C ₆ H ₅ CH ₂ -Cl -1: 400 ratio) (Example 13).

Example 14

The method is carried out as in example 3, except that both water and benzyl chloride are metered into the catalyst solution.

Example 15

The method is carried out as in example 3, except that both water and benzyl chloride are metered into the charge supply line.

Example 16

The method is carried out as in example 3, except that benzyl chloride is dosed into the catalyst solution, and water into the charge supply line.

Example 17

The method is carried out as in example 3, except that chlorobenzene is used as the second modifier.

Example 18

The method is carried out as in example 3, except that 1-chloro, 1-phenylethane is used as the second modifier.

Example 19

The method is carried out as in example 1, except that 22.15 t / h of isobutylene and 0.64 t / h of isoprene are fed into the polymerizer; the concentration of isobutylene in the mixture is 35 wt.%.

Example 20

The method is carried out as in example 3, except that 22.15 t / h of isobutylene and 0.64 t / h of isoprene are fed into the polymerizer; the concentration of isobutylene in the mixture is 35 wt.%.

Example 21. The method is carried out as in example 3, except that 1-chloro-3-phenylpropane is used as the second modifier.

The results obtained by implementing the method in accordance with examples 1 to 21 are shown in the table.

From the table it follows that in the method for producing butyl rubber during the copolymerization process in the presence of two catalyst modifiers - aluminum chloride, one of which is water and the other is selected from the group of organic substances with the general formula C ₆ H ₅ -X, where X is halogen or a radical with the formula C _n H _{2n + 1} -Gal, where n = 1-2, the initial reaction rate decreases, which leads to a more uniform distribution of the reaction heat throughout the reactor, an increase in the heat removal efficiency and, accordingly, an increase in the ranges of polymerizers. The total conversion of isobutylene during the passage of the reaction mass through the reactor does not decrease, but increases with certain ratios of the components of the catalytic system, which, together with an increase in the path of polymerizers, leads to an increase in rubber production. The optimal molar ratio of AlCl ₃ : H ₂ O - 1: 0.5 ÷ 20. When the ratio decreases below 0.5 (Example 4), the initial copolymerization rate significantly increases and the polymerization paths decrease, which does not allow working at five reactors during the day and ultimately reduces the daily production of rubber. When the ratio increases above 20 (example 8), there is not a sufficient activation of the catalyst. At a moderate initial copolymerization rate, the conversion of isobutylene decreases, which also leads to a decrease in rubber production.

The optimal molar ratio of AlCl ₃ : C ₆ H ₅ -X - 1: 50 ÷ 350. When this ratio decreases below 50 (Example 9), a too significant decrease in the initial copolymerization rate occurs, which in this case is accompanied by a decrease in conversion and daily production. When the ratio increases above 350 (example 13), the initial copolymerization rate decreases slightly and does not allow to stabilize the heat removal, as a result it is not possible to increase the duration of the runs of polymerizers.

When conducting experiments in accordance with examples 1-18, the concentration of isobutylene in the mixture was maintained at the same level of 29.6 wt.%. The implementation of the proposed method allows to increase this value. When increasing the concentration of isobutylene to 35 wt.% In the conditions of the copolymerization of the prototype (example 19), the runs of polymerizers are reduced to such an extent that it becomes unprofitable to carry out the process due to a sharp decrease in productivity. The process in accordance with the claimed technical solution (example 20) allows to increase the concentration of isobutylene to 35 wt.%, While the duration of the runs of the polymerizers is reduced slightly and there is the possibility of working at 5 reactors during the day, which significantly increases the daily output.

Claims (2)

1. A method of producing butyl rubber, including the preparation of a mixture of isobutylene, isoprene and return products, copolymerization of the mixture in a diluent — methyl chloride in several reactors in parallel in the presence of an aluminum chloride catalyst, including rubber degassing, processing of unpolymerized monomers and a diluent — methyl chloride, averaging, drying finished polymer on extrusion machines and its briquetting, characterized in that the copolymerization process is carried out in the presence of two modes ikatorov catalyst, one of which - water, and the other is selected from the group consisting of organic compounds of the general formula C ₆ H ₅ -X, where X - a halogen or a radical of the formula -C _n H _{2n + 1} Hal, where n = 1-2, the molar ratio of AlCl ₃ : H ₃ O is maintained within 1: 0.5 ÷ 20, and the molar ratio of AlCl ₃ : C ₆ H ₅ -X is within 1: 50 ÷ 350. 2. The method according to claim 1, in which both modifiers are dosed either in the mixture or in the catalyst solution, or one of them in the mixture, and the other in the catalyst solution.

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