RU2494116C1 - Method of producing butadiene rubber - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to petrochemical industry, particularly production of butadiene rubber by solution polymerisation and can be used in production of plastic, industrial rubber articles and tyres. The method involves continuous polymerisation of butadiene in the medium of a hydrocarbon solvent in the presence of an initiating system which is an organolithium compound and a modifying additive which is a mixture of calcium, sodium and potassium alcoholates in molar ratio of 1:0.2-10:0.02-5, with molar ratio of lithium to the modifying additive of 1:0.01-1.0, respectively, with consumption of the organolithium compound of 4-10 moles per ton of butadiene.

EFFECT: invention enables to obtain polybutadiene with a mixed microstructure, Mooney viscosity of 40-60 units, viscosity (5,43 wt % rubber solution in toluene) of 150-200 mPa*s, low content of the gel fraction and low cold flow.

2 tbl, 9 ex

Description

The invention relates to the field of production of butadiene rubbers by solution polymerization, which can be used in the production of plastics, rubber products and tires.

A known method for producing polymers of conjugated dienes with a content of at least 60% vinyl units by polymerization of butadiene-1,3 or isoprene in an inert hydrocarbon solvent, for example, hexane, heptane, benzene. In the presence of an anionic initiator consisting of an organomagnesium compound of the general formula MgR ₂ , where R is a hydrocarbon radical containing from 1 to 10 carbon atoms and sodium mercaptide, of the general formula R ′ (SNa) _n , where R ′ is a hydrocarbon radical containing from 1 up to 10 carbon atoms, n is from 1 to 3, for example, sodium n-butyl mercaptide with a molar ratio of Mg: Na from 0.1: 1 to 10: 1. In the presence of an amine, for example tetramethylethylenediamine (TMEDA). With subsequent catalyst deactivation, isolation and drying of the polymer by known methods (US patent No. 4174431, IPC B01J 31/12; C08F 36/04; 36/00; 004/50; 004/54; 004/08, publ. 13.11.79) . The polymerization by this method is carried out by sequentially adding to the solution of the monomer in a hydrocarbon solvent amine, dialkyl magnesium and sodium mercaptide, keeping the polymerization mixture at a temperature of 30-80 ° C for 1-18 hours.

The disadvantages of this method are to obtain a polymer with an unpleasant odor, the formation of a gel and the "fouling" of the polymerizer with a gel-like polymer.

A known method of producing polymers of conjugated dienes with a content of 1, 2- or 3, 4-units of at least 60% by anionic polymerization of butadiene or isoprene using bimetallic initiators of the general formula NaMgR ₃ , where R is an alkyl radical with a carbon atom content of from 2 to 14 , cycloalkyl or aryl in the presence of an oligomeric oxolanylalkane: for example, dimeric 2,2-bis (2-oxalanyl) propane with a molar ratio of the latter to the bimetallic initiator from 0.5: 1.0 to 10: 1.0, deactivation of the catalyst by isolation and drying polymer famous methods. The molecular weight of the polymer depending on the polymerization conditions is in the range from 1000 to 500000 (US Patent 4,647,635, MKI C08F 36/04; 36/00; 4/00; 4/44; 004/08 publ. 04.03.87).

The disadvantage of this method is the "fouling" of the polymerizer with a gel-like polymer, which requires frequent cleaning of the polymerizer. In this case, there is a large loss of polymer in the form of an insoluble gel.

A known method of producing polydienes by polymerization of butadiene-1,3 or isoprene in an inert hydrocarbon solvent in the presence of an anionic initiator is an organomagnesium compound and a sodium-containing organic compound of the general formula RONa, where R is C ₁ -C ₁₀ alkyl or R′O (CH ₂ ) _n where R ′ is C1-C4 alkyl, an = 2-4, and the organomagnesium compound is C ₁ -C ₄ dialkyl magnesium or the product of the interaction of magnesium with butadiene-1, 3 or isoprene or pentadiene-1, 3. The polymerization process is carried out pre-formed into polymer the isolation zone of the complex of sodium-containing organic compounds with isoprene or butadiene, followed by the introduction of an organomagnesium compound (RF patent No. 2061704, IPC C08F 136/04 priority 30.09.92. publ. 10.06.96, Bull. No. 16).

The disadvantage of this method of producing polydiene is that using the specified initiating system it is impossible to obtain polybutadiene with a low content of vinyl units.

A known method of producing low molecular weight polybutadiene by polymerization of butadiene-1,3 in a hydrocarbon solvent in the presence of a catalytic system consisting of an organic compound of magnesium and an alkali metal alkoxide, where butyl-2-ethylhexyl magnesium is used as an organic compound of magnesium in an amount of 15-20 mol per ton of monomer and sodium or potassium tetrahydrofurfurylate is used as alkali metal alkoxide at a molar ratio of magnesium: alkali metal equal to from 1: 0.25 to 1: 2.0. The polymerization is carried out in toluene at a temperature of 20-80 ° C with a continuous supply of butadiene in toluene, where the catalyst system is loaded (RF patent No. 2082720, IPC C08F 136/06, priority 04/14/95. Publ. 06/27/97, bull. No. 18) .

The disadvantage of this method of obtaining low molecular weight polybutadiene is the low polymerization rate and high consumption of organomagnesium compounds, as well as the inability to obtain vinyl units below 30%.

The closest to the present invention in technical essence and the achieved result is a method for producing butadiene polymers under conditions of continuous polymerization of butadiene with low (10-20%) and controlled vinyl content, narrow MMP and low content of gel fraction. As the initiating system, an organolithium compound and a modifying additive are used, which is a mixture of magnesium, sodium and potassium alcoholates in a molar ratio of 1: 0.1-2: 0.2-1.5, with a molar ratio of lithium: modifying additive equal to 1: 0.01-1.0, and α-olefins or substituted benzenes, or mixtures thereof in a weight ratio of hydrocarbon solvent: antigel additive, equal to 98-50: 2-50 (RF patent No. 2402574, IPC C08F, are used as an anti-gel additive) 136/06, publ. 10/27/2010, bull. No. 30).

The disadvantages of this method are the high ductility and cold flow of the resulting polybutadiene. This complicates its water degassing, leads to increased consumption of steam and anti-agglomerator. And at the stages of separation and drying, there is an intensive adhesion of rubber on the surface of the equipment. In addition, the low solubility of the modifying additive in aliphatic hydrocarbon solvents and the presence of finely dispersed magnesium particles of sludge are accompanied by the precipitation of the modifier, clogging of pipelines, flow meters and, as a result, uneven supply of the modifying additive to the reaction medium.

The objective of the proposed method is to obtain polybutadiene under conditions of continuous polymerization of butadiene with a mixed microstructure, a Mooney viscosity of 40-60 units, a viscosity (5.43% by weight of a solution of rubber in toluene) 150-200 MPa · s, a low content of gel fraction and cold flow no more than 7 mm / h.

The problem is solved in that the method of producing butadiene rubbers by continuous polymerization of a monomer in a hydrocarbon solvent in the presence of an initiating system consisting of an organolithium compound and a modifying additive, which is a mixture of calcium, sodium, and potassium alcoholates in a molar ratio of 1: 0.2 ÷ 10 : 0.02 ÷ 5 with a molar ratio of lithium: modifying additive equal to 1: 0.01 ÷ 1.0, respectively, when the flow rate of the organolithium compound is 4-10 mol per ton of butadiene.

The use of a mixture of calcium, sodium, and potassium alcoholates in a modifying additive of an organolithium compound during continuous polymerization of butadiene allows one to obtain a polymer with stable, predetermined characteristics. Sodium alcoholates effectively initiate polymerization and increase the speed of the process. Potassium compounds are involved in transfer reactions of the growing polymer chain, which is necessary to suppress the formation of gel fractions. Calcium alcoholates increase the solubility of the modifying additive and increase the likelihood of chain transfer reactions to the polymer involving potassium ions, which increases the branching of the polymer and reduces its cold flow.

Obtaining a mixture of calcium, sodium and potassium alcoholates can be carried out in two ways:

1) Calcium, sodium and potassium, alcohol or a mixture of alcohols are charged into a hydrocarbon solvent. Next, the reaction mass is heated to the melting point of alkali metals. In this case, the interaction of the hydroxyl groups of the alcohol with alkali metals occurs. Then, the reaction of sodium substitution with calcium proceeds with the release of an alkali metal. Potassium under the reaction conditions is not replaced by calcium. Mixed alcoholates with a given content of calcium, sodium and potassium alcoholates are obtained depending on the reaction time. Sequential loading of alkali and alkaline earth metals is also possible.

2) Potassium hydroxide and alcohol or a mixture of alcohols are charged into a hydrocarbon solvent. The mixture is thermostated at a temperature of more than 100 ° C, while the formation of an alkali metal alcoholate and water proceeds. Water in the form of an azeotrope is removed from the reaction zone, and the solvent is returned to the reaction zone. After completion of the reaction, as evidenced by the liberated water, sodium and calcium are added to the solution, and the reaction mixture is continued to thermostat. In this case, sodium interacts with the residues of the hydroxyl groups of the alcohol, and the alkaline earth metal replaces the sodium in the alcoholate with the release of an alkali metal. Depending on the synthesis conditions, mixed alcoholates with a given content of alkaline and alkaline-earth alcoholates are obtained.

As alcohols, it is preferable to use N, N, N ′, N′-tetra (β-hydroxypropyl) ethylenediamine (Lapramol-294 according to TU 2226-010-10488057-84) and tetrahydrofurfuryl alcohol.

The concentration of the modifying additive, which is a mixture of calcium, sodium, and potassium alcoholates, is determined in terms of total alkalinity.

The alleged invention is illustrated by the following examples:

Example 1

Sodium 17.20 kg, potassium 14.60 kg, toluene 600 l and 3 kg of calcium are loaded in a stream of 1000 l, equipped with a stirrer, a jacket for supplying and removing heat, fittings for loading reacting components and unloading the finished product in the form of granules 1-3 mm in size and the contents of the apparatus are heated to 105 ° C. Then a stirrer is turned on and a mixture containing 69.00 kg of Lapramol-294 and 8.00 kg of tetrahydrofurfuryl alcohol is metered into a suspension of sodium-potassium-calcium for 2 hours. After completion of the reaction between sodium, potassium and hydroxyl groups of alcohols, as evidenced by the cessation of hydrogen evolution, the contents of the apparatus are kept at a temperature of 110-120 ° C for 12 hours. In this case, the reaction of substitution of sodium for calcium proceeds. Then the contents of the apparatus are cooled and a sample is taken for analysis.

The conditions for the preparation of mixed alcoholates and the results of their analysis are shown in table 1.

Example 2

0.65 kg of potassium hydroxide, 230 l of toluene, 70.00 kg of Lapramol-294 are loaded into a 500 liter apparatus No. 500, equipped with a stirrer, a jacket for heat supply, fittings for loading reagents and unloading the finished product, in a stream of nitrogen 32.00 kg of tetrahydrofurfuryl alcohol. The apparatus is connected to a heat exchanger in which the toluene-water azeotrope pair is condensed. The contents of the apparatus are heated to a temperature of 120 ° C. In this case, potassium hydroxide reacts with the hydroxyl group of the mixture of alcohols with the formation of potassium alcoholate and water. Water in the form of an azeotrope with toluene through a heat exchanger is collected in a tank, where it is separated from toluene. Toluene returns to the reaction zone, and water is collected and its amount is determined. 4 hours after completion of the reaction, as evidenced by the calculated amount of released water, the solution is analyzed. 1.000 kg of sodium, 14.00 kg of calcium, 400 l of toluene and the contents of the apparatus are loaded into a No. 2 unit with a volume of 1000 l, equipped with a stirrer, a jacket for supplying and removing heat, fittings for loading reacting components and unloading the finished product heated to 100 ° C, turn on the stirrer and dispense 200 l of a toluene solution of a mixture of potassium alcoholate and alcohols from apparatus No. 1 within 2 hours. After completion of the dosage of this mixture, the reaction mass is stirred for another 10 hours at a temperature of 115-120 ° C. Then the contents of the apparatus are cooled and a sample is taken for analysis.

The conditions for the preparation of mixed alcoholates and the results of their analysis are shown in table 1.

Example 3

Sodium 20.07 kg, potassium 9.75 kg, toluene 650 l and 5.00 are loaded into a 1000 l apparatus equipped with a stirrer, a jacket for supplying and removing heat, fittings for loading reacting components and unloading the finished product, in a stream of dried nitrogen kg of calcium in the form of granules 1-3 mm in size and the contents of the apparatus are heated to 105 ° C. Then the mixer is turned on and a mixture containing 50.00 kg of Lapramol-294 and 17.40 kg of tetrahydrofurfuryl alcohol is dosed to the sodium-potassium-calcium suspension for 2 hours. After completion of the reaction between sodium, potassium and hydroxyl groups of alcohols, as evidenced by the cessation of hydrogen evolution, the contents of the apparatus are kept at a temperature of 110-120 ° C for 12 hours. In this case, the reaction of substitution of sodium for calcium proceeds. Then the contents of the apparatus are cooled and a sample is taken for analysis.

The conditions for the preparation of mixed alcoholates and the results of their analysis are shown in table 1.

Example 4

In apparatus No. 1 with a volume of 500 l equipped with a stirrer, a jacket for heat supply, fittings for loading reagents and unloading the finished product, 7.20 kg of potassium hydroxide, 230 l of toluene, 175.00 kg of Lapramol-294 are loaded and 61.00 kg of tetrahydrofurfuryl alcohol. The apparatus is connected to a heat exchanger in which the toluene-water azeotrope pair is condensed. The contents of the apparatus are heated to a temperature of 120 ° C. In this case, potassium hydroxide reacts with the hydroxyl group of the mixture of alcohols with the formation of potassium alcoholate and water. Water in the form of an azeotrope with toluene through a heat exchanger is collected in a tank, where it is separated from toluene. Toluene returns to the reaction zone, and water is collected and its amount is determined. 4 hours after completion of the reaction, as evidenced by the calculated amount of released water, the solution is analyzed. In apparatus No. 2 with a volume of 1000 l, equipped with a stirrer, a jacket for supplying and removing heat, fittings for loading reacting components and unloading the finished product, 17.20 kg of sodium, 10.00 kg of calcium, 400 l of toluene and the contents of the apparatus are loaded in a stream of nitrogen heated to 100 ° C, turn on the stirrer and dosed for 2 hours 200 l of a toluene solution of a mixture of potassium alcoholate and alcohols from apparatus No. 1. After completion of the dosage of this mixture, the reaction mass is stirred for another 10 hours at a temperature of 115-120 ° C. Then the contents of the apparatus are cooled and a sample is taken for analysis.

The conditions for the preparation of mixed alcoholates and the results of their analysis are shown in table 1.

Example 5

The synthesis of polybutadiene is carried out in a battery of two reactors with a volume of 20 m ³ each, equipped with a stirrer, a supply system of solvent, monomers, catalyst and a jacket with a coolant. The butadiene charge in a hydrocarbon solvent-nefras with a toluene content of 5% is continuously fed into the first reactor along the way, at the rate of 18 t / h of solvent and 2.0 t / h of butadiene, and 230 l / h (161 kg / h) of solution -C ₄ H ₉ Li in nephras with a concentration of 0.087 mol / l and 29 l / h (38.5 kg / h) of a modifier solution in toluene obtained in Example 1 and diluted to a concentration of 0.007 mol / l. The formation of the catalytic complex occurs in the “in situ” mode. The ratio of nC ₄ H ₉ Li: modifier is 1: 0.01. The consumption of active metal is 10 mol per ton of monomer. The conversion of butadiene in the second reactor is 100%. After completion of the polymerization, the polymer solution is stabilized and sent to degassing, isolation and drying.

The resulting polybutadiene is tested according to standard methods.

The polymer properties are presented in table 2.

Example 6

The synthesis of polybutadiene is carried out as in example 5, but a dose of 115 l / h (80.5 kg / h) of a solution of HC ₄ H ₉ Li in nephras with a concentration of 0.087 mol / l and 142.8 l / h (107.1 kg / h) a solution of the modifier in toluene obtained in example 2 and diluted to a concentration of 0.035 mol / L. The formation of the catalytic complex occurs in situ. The ratio of nC ₄ H ₉ Li: modifier is 1: 0.5. The consumption of active metal is 5 mol per ton of monomer. The conversion of butadiene in the second reactor is 100%. After completion of the polymerization, the polymer solution is stabilized and sent to degassing, isolation and drying.

The resulting polybutadiene is tested according to standard methods.

The polymer properties are presented in table 2.

Example 7

The synthesis of polybutadiene is carried out as in example 5, but 183.8 l / h (128.7 kg / h) of a solution of HC ₄ H ₉ Li in nephras with a concentration of 0.087 mol / l and 160 l / h (120 kg / h) are dosed a solution of modifier in toluene obtained in example 3 and diluted to a concentration of 0.01 mol / L. The formation of the catalytic complex occurs in the “in situ” mode. The ratio of HC ₄ H ₉ Li: modifier is 1: 0.1. The consumption of active metal is 8 mol per ton of monomer. The conversion of butadiene in the second reactor is 100%. After completion of the polymerization, the polymer solution is stabilized and sent to degassing, isolation and drying.

The resulting polybutadiene is tested according to standard methods.

The polymer properties are presented in table 2.

Example 8

The synthesis of polybutadiene is carried out as in example 5, but 91.9 l / h (64.3 kg / h) of a solution of nC ₄ H ₉ Li in nephras with a concentration of 0.087 mol / l and 228.5 l / h are dosed (171, 4 kg / h) of a solution of modifier in toluene obtained in example 4 and diluted to a concentration of 0.035 mol / L. The formation of the catalytic complex occurs in the “in situ” mode. The ratio of nC ₄ H ₉ Li: modifier is 1: 1. The consumption of active metal is 4 mol per ton of monomer. The conversion of butadiene in the second reactor is 100%. After completion of the polymerization, the polymer solution is stabilized and sent to degassing, isolation and drying.

The resulting polybutadiene is tested according to standard methods.

The polymer properties are presented in table 2.

Example 9 (prototype).

The synthesis of polybutadiene is carried out in a battery of two reactors with a volume of 20 m ³ each, equipped with a mixer, a solvent supply system, catalyst monomers and a jacket with a coolant. The butadiene charge in a hydrocarbon solvent-nefras, with a toluene content of 6%, at the rate of 13 t / h of solvent and 1.5 t / h of butadiene is continuously fed into the first reactor along the way and dosed at the same time 60 l / h (40.2 kg / h ) a solution of n-C ₄ H ₉ Li in nephras with a concentration of 0.1 mol / l and 12 l / h (10.4 kg / h) of a modifier solution in toluene, which is a mixture of magnesium, sodium and potassium alcoholates in a molar ratio of 1: 2: 1.5 and diluted to a concentration of 0.005 mol / L. The formation of the catalytic complex occurs in situ. The ratio of nC ₄ H ₉ Li: modifier is 1: 0.2. The consumption of active metal is 6 mol per ton of monomer. The conversion of butadiene in the second reactor is 100%. After completion of the polymerization, the polymer solution is stabilized and sent to degassing, isolation and drying.

The resulting polybutadiene is tested according to standard methods.

The polymer properties are presented in table 2. It follows from the examples that the proposed method allows to obtain polybutadiene under conditions of continuous polymerization of butadiene with a mixed microstructure, a Mooney viscosity of 40-60 units, a viscosity (5.43% by weight of a solution of rubber in toluene) 150 -200 MPa · s, low gel fraction and cold flow no more than 7 mm / h.

table 2 The properties of the polymers according to the claimed method and prototype Example No. Number 5 Number 6 Number 7 Number 8 No. 9 on the prototype Mooney viscosity, conv. units 52 57 40 60 45 Microstructure,% wt. 1,2- eleven thirty fourteen 41 12 1,4-cis 38 32 35 24 37 1,4-trans. 51 38 51 35 51 Viscosity (5.43% by weight of a solution of rubber in toluene), MPa · s 200 165 150 177 170 Mass fraction of gel fraction,% 0.02 0.01 0.01 0.01 0.015 Cold flow, mm / h 7 3 four 5 10

Claims (1)

A method for producing butadiene rubbers by continuous polymerization of a monomer in a hydrocarbon solvent in the presence of an initiating system, characterized in that an organolithium compound and a modifying additive, which is a mixture of calcium, sodium and potassium alcoholates, in a molar ratio of 1.0: 0 are used as the initiating system , 2-10.0: 0.02-5.0 with a molar ratio of lithium: modifying additive equal to 1.0: 0.01-1.0, respectively, with an organolithium compound consumption of 4-10 mol per ton of butadiene.