RU2091396C1 - Method of preparing polyisobutylene - Google Patents

Abstract

FIELD: preparation of polymeric materials. SUBSTANCE: polyisobutylene having low molecular weight is prepared by polymerization of isobutylene in toluene at 0-60 C. The catalyst is titanium tetrachloride or titanium tetrachloride and trialkyl aluminium at titanium to aluminium molar ratio of 1-100. Amount of titanium tetrachloride is 0.1-2.5 moles per 100 kg of monomer. 10-50 wt % of its total amount are first introduced followed by portionwise addition of the remaining isobutylene and polymerization thereof at temperature given above. Each subsequent portion is added at conversion of at least 90%, and process is carried out to final polymer content of 50-80 wt % in solution. EFFECT: more efficient preparation method. 1 tbl

Description

 The invention relates to the technology of polymerization processes of isobutylene and can be used in the synthetic rubber industry, and the resulting polymer in the manufacture of additives, lubricants, adhesives, perfumes and many other purposes.

A known method of producing polyisobutylene by polymerization of isobutylene in n-heptane at 0 ^o C in the presence of triethylaluminum and titanium trichloride with a molar ratio of 1 to 8-9 [1]
The disadvantage of this method is to obtain insoluble products.

Known methods for producing low molecular weight polyisobutylene with different molecular weights from 600 to 3500 and up to 20 • 10 ³ by polymerization of isobutylene in butanbutylene fraction in the presence of a catalyst of aluminum trichloride or a complex of aluminum trichloride with alkyl aromatic compounds (toluene, butylbenzene, etc.) when temperature -20 30 ^o C and below, the content of isobutylene 15-60 wt. [2]
The molecular weight is controlled by changing the amount of catalyst, which leads to very high costs in case of obtaining low values (less than 3500), the need to divide the product by distillation, special washing, high energy costs for removing the heat of reaction.

The closest to the proposed invention in technical essence and the achieved result is a method for producing polyisobutylene by polymerization of isobutylene in isooctane at a temperature of from (-25) to 75 ^o C. In this case, triethyl aluminum and titanium tetrachloride catalysts are successively introduced into the solvent based on the molar ratio titanium aluminum 2 : 1 or 1: 16 and further, isobutylene is introduced for 2.5-3.0 hours. The amount of catalyst is determined based on 1 wt. aluminum triethyl in solvent [3]
In the known method, a very high consumption of components of the catalytic system, a large (relatively) molecular weight of the obtained polymer and its wide molecular weight distribution, low conversion of the monomer at temperatures above 0 ^o C (about 30% for 3 hours).

 The objective of the present technical solution is to obtain polyisobutylene having a narrow molecular weight distribution, at low catalyst costs and with a high polymer content in toluene at the end of the process, using widely used titanium and aluminum compounds.

The essence of the invention lies in the fact that the polymerization of isobutylene is carried out in toluene in the presence of titanium tetrachloride or titanium tetrachloride and aluminum trialkyl, taken from the calculation of titanium tetrachloride in an amount of from 0.1 to 2.5 mol per 10 kg of monomer and molar ratio of titanium aluminum from 100: 1 to 1: 1 and the process is carried out at 0-60 ^o C and the initial introduction of the monomer in an amount of 10-50 wt. of its total amount with subsequent portioned introduction of the remaining monomer and polymerization of it at the same temperature, with each subsequent portion being introduced at a conversion of at least 90% and the process is carried out until the final polymer content in the solution is 50-80 wt.

 The limits on the concentration of titanium tetrachloride are established from a decrease in the efficiency of the process or the insignificance of the influence of this parameter on the process and the properties of the polymer with a further increase. Limitations on the initial introduction of the monomer are associated with certain requirements for the molecular weight and polydispersity index of polyisobutylene, as well as difficulties in removing the heat of reaction. The choice of catalyst is dictated by the requirements for the molecular weight of the polymer, the speed of the process, the possible implementation of the number of portions (stages) while maintaining the total time within 2.5-3 hours. Combination with the conditions is the know-how of the invention.

 Within the indicated titanium: aluminum ratios, the conditions for the implementation of a multi-stage process and the achievement of the maximum level of polyisobutylene are created. A higher value is difficult to achieve due to the death of a large amount of catalyst associated with microimpurities falling during the additional introduction of the monomer and, as a result, changes in the molecular parameter of the polymer. Low values of the polymer content with the necessary properties can be achieved with a one-stage version, i.e. without additional technological complications, with the exception of heat removal.

Maintaining the reaction temperature below 0 ^o C requires special refrigerants (except typical brine), which complicates the process and increases the molecular weight of polyisobutylene, and the upper limit is chosen from the conditions of safety, the availability of equipment, and the possibility of secondary reactions.

 After the polymerization of isobutylene, an aliphatic alcohol is introduced into the reaction mass to destroy the catalyst residues and is isolated by known methods by washing with water with soda or alkali and water and distilling off the solvent on a rotary film evaporator.

, динамической вязкостью по Хепплера, молекулярной массе по Штаудингеру (хлороформ, 20^oC).The polymer is characterized by molecular parameters

, Heppler dynamic viscosity, Staudinger molecular weight (chloroform, 20 ^o C).

 The absolute values of the process conditions are calculated based on the data presented in the table, which also shows the properties of the polymer.

Example 1 (prototype). In a four-necked flask equipped with a stirrer, a bubbler, a reflux condenser and a thermometer, placed in a thermostatic bath, the calculated amount of isooctane is introduced, from which air is removed by washing with nitrogen. Then, in a weak stream of isobutylene, the calculated amount of triethyl aluminum (15% solution in kerosene) and titanium tetrachloride (TiCl ₄ ) (100%) are fed into the flask and isobutylene is bubbled continuously for 2.5 hours. The process is carried out at 8 ^o C, the conversion of monomer is 83.7%
Example 2 (prototype conducted by the authors). In a metal laboratory reactor with a capacity of 3 l, equipped with devices for loading and unloading reagents, measuring pressure and temperature, a stirrer and a jacket for thermostating, 845 g (1221.1 ml) of isooctane, previously dried over active aluminum oxide and deoxygenated, 255.5 g are introduced isobutylene (425.8 ml), then a solution of triethylaluminum in kerosene at the rate of 1.0 wt. in a solvent (concentrations of 16.7 wt.), i.e. 60 g or 90 ml and a solution of titanium tetrachloride in isooctane based on the molar ratio of aluminum to titanium 1: 2 (concentrations of 1.82 mol / l). All loading and unloading operations are carried out in a stream of dried and oxygen-free nitrogen.

The process is carried out at 30 ^o C for 4 hours, the polymer yield (conversion) is 56.1%. In this and other examples, the calculation of the concentration of the mixture (total amount of solvent) is carried out taking into account the amount of solvent supplied with the catalyst components.

Example 3. Carried out as described in example 2. In the reactor load a mixture consisting of 356.5 g (409.8 ml) of toluene and 600 g (1000 ml) of isobutylene, cooled to -15 20 ^o C. Next, toluene solutions of tetrachloride are fed. titanium (with a concentration of 0.12 mol / L) at the rate of 0.6 mol per 100 kg of isobutylene and 2 minutes after stirring, a toluene solution of triisobutylaluminum (with a concentration of 0.18 mol / L) is supplied at a molar ratio of titanium: aluminum of 1: 1.

The process is carried out at 60 ^o C for 5 minutes, the polymer yield is 100%
The polymerization process of the first portion is carried out at 30 ^o C for 5 min, the polymer yield of 99%
Next, isobutylene is fed into the reactor in an amount of 10% wt. of the total and at the same temperature, the polymerization process is carried out 5 minutes before the 99% conversion. Similar operations are repeated 8 more times (i.e., only 9 additional stages and the initial one). The final polymer content for a total time of 50 min reaches 80% wt.

Example 4. Carried out as described in example 2. Initially, in the reactor charge, consisting of 706.5 g (812.1 ml) of toluene and 250 g of isobutylene (416.7 ml) and cooled to -15-20 ^o C, a solution titanium tetrachloride (concentrations of 0.125 mol / l) in an amount of 2.5 mol per 100 kg of total monomer.

The polymerization process of the first portion is carried out at 60 ^o C for 30 minutes and the polymer yield is 98%
Next, isobutylene in an amount of 25 wt. of the total and at the same temperature, the polymerization process is carried out 30 minutes before the conversion of 98%. A similar operation is repeated 1 more time (i.e. only 2 additional stages and the initial one). The final polymer content for a total time of 90 minutes is 50% wt.

Example 5 (according to the invention). An initial step is carried out as described in Example 2. A mixture consisting of 913 g (1049.4 ml) of toluene and 80 g (133.3 ml) of isobutylene, cooled to -15 ^o C, a solution of titanium tetrachloride (concentration of 0.10 mol / l) in an amount of 0, is loaded into the reactor. 5 mol for the whole monomer and a solution of triisobutylaluminum (concentration of 0.1 mol / l) based on the molar ratio of titanium aluminum 1: 1.

Example 6. Carried out as described in example 2. Initially, a charge consisting of 867.4 g (997.0 ml) of toluene and 130 g (216.7 ml) of isobutylene, cooled to -15-20 ^o C tetrachloride solution is loaded into the reactor titanium (concentration of 0.065 mol / l) in an amount of 0.1 mol per 100 kg of monomer and after 2 min a solution of triethylaluminum (concentration of 0.065 mol / l) based on the molar ratio titanium aluminum 100 1. The process is carried out at 40 ^o C for 15 min the polymer yield is 100%
Then served in the reactor isobutylene at the rate of 20 wt. of the total amount and at the same temperature, the polymerization process is carried out for 15 minutes, the polymer yield is 100% wt. Similarly, the operation is repeated 3 more times (i.e., the number of additional stages 4 and the initial one). The final polymer content over a total time of 75 minutes is 65 wt.

Example 7. It is carried out as described in example 2. Initially, a charge consisting of 787.0 g (904.6 ml) of toluene and 200 g (333.3 ml) of isobutylene, cooled to -15) -20 ^o C, is loaded into the reactor, a solution of titanium tetrachloride (concentration 0.12 mol / L) in an amount of 0.6 mol per 100 kg of total monomer and a solution of triisobutylaluminum (concentration 0.12 mol / L) based on a molar ratio of titanium aluminum 2: 1. The polymerization process is carried out at 0 ^o C for 4 minutes, the polymer yield is 99 wt.

Then served in the reactor isobutylene at the rate of 5 wt. of the total amount and at the same temperature, the polymerization process is carried out for 4 minutes to a conversion of 99%
Similar operations are repeated 9 more times (i.e., the total number of additional stages is 10 and the initial one). The final polymer content for a total time of 44 minutes is 75% wt.

 As can be seen from the results presented in the table and obtained by examples, the proposed technical solution allows to obtain polyisobutylene with a very low molecular weight at a high polymer content in the solvent.

Claims (1)

A method of producing polyisobutylene by polymerization of isobutylene in a hydrocarbon solvent in the presence of a catalyst containing titanium tetrachloride, characterized in that toluene is used as a hydrocarbon solvent, titanium tetrachloride or titanium tetrachloride and trialkyl aluminum are used at a molar ratio of titanium aluminum of 1,100, when the amount of titanium tetrachloride 0.1 to 2.5 mol per 100 kg of monomer, the process is carried out at 0 60 ^o With the initial introduction of the monomer 10 50 wt. of its total amount, followed by portionwise introduction of the remaining isobutylene and polymerization of it at the same temperature, with each subsequent portion being introduced at a conversion of at least 90% and the process is carried out to a final polymer content of 50 to 80 wt.

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