RU2142474C1 - Method of preparing low-molecular 1,2-polybutadiene - Google Patents

Abstract

FIELD: synthetic rubber industry, more particularly preparation of anticorrosion and electroinsulating coatings, manufacture of tires and industrial rubber products. SUBSTANCE: described is method of preparing low molecular 1,2-polybutadiene by polymerization of butadiene-1,3 in hydrocarbon solvent in the presence of catalyst system comprising organic lithium compound, alkali metal alkoxide and electron donor additive. Electron donor compound is diethylene glycol diethyl ether and/or tetrahydrofurfuryl alcohol ether; alkali metal alkoxide is potassium tetrahydrofurfurylate or potassium diisobutyl aluminate, and polymerization is carried out in toluene at 20-80 C by successive addition of butadiene-1,3 to solvent to concentration of 10-60 wt % and catalyst system components provided that n-butyl lithium is used within 10-70 moles per ton of monomers and potassium to lithium molar ratios from 0.03 to 0.8 and electron donor additive to lithium molar ratio from 0.1 to 1.5. EFFECT: method makes it possible to obtain low-molecular polybutylene containing more than 60 % of vinyl links at low catalyst consumption rates and high process rate, wider range of electron donor compounds. 4 ex, 1 tbl

Description

 The invention relates to the polymerization of butadiene-1,3 and can be used in the synthetic rubber industry, and the resulting polymer serves as the basis for the manufacture of electrical insulating, anti-corrosion coatings, as a plasticizing additive in the manufacture of tires, rubber products.

 Known methods for producing 1,2-polybutadiene by polymerization of butadiene-1,3 in a hydrocarbon medium under the action of combined catalytic systems of potassium n-butyllithium tetrahydrofurfurfurylate (SU 1758042 C1, C 08 F 136/06, 02.30.92) or potassium diisobutylaluminate (RU 2017752 C1, C 08 F 136/04, 08/15/94) in the presence of additives.

 A disadvantage of the known methods is the lack of the ability to obtain polybutadiene with a high content of vinyl groups of 50 percent and a more or less assortment of electron-donating additives.

The closest to the proposed invention in technical essence, the achieved results is a method for producing polybutadiene by polymerization of butadiene-1,3 in an aromatic solvent at a temperature of from 30 to 80 ^o C, while butadiene-1,3 is introduced into the solvent sequentially to a concentration of 10- 50 wt.%, N-butyllithium in an amount of 6-40 moles / ton number, a compound selected from the group consisting of diethylene glycol dimethyl ether, permethylated polyethylene polyamines, dipiperidinethane, tetramethylethylenediamine, at a molar ratio compounds to n-butyllithium, equal to 0.5-2.0, followed by exposure of the resulting mixture for at least two minutes and the introduction of potassium tetrahydrofurfurylate with an atomic ratio of potassium to lithium equal to 0.05-2.0 (RU 2082722 C1, C 08 F 136/06, 06/27/97).

 The disadvantages of this known method also include the limited group of compounds, the need to comply with the sequence of introduction of the components of the catalytic system.

 An object of the present invention is a method for producing polybutadiene having a molecular weight of up to 50,000, containing more than 50% vinyl units, expanding the group of electron-donating compounds in any order in which the components of the catalyst system are introduced.

The essence of the proposed technical solution lies in the fact that diethylene glycol diethyl ether and / or tetrahydrofurfuryl alcohol ether, alkali metal alkoxide are used potassium tetrahydrofurfurylate or potassium diisobutylaluminate, and polymerization is carried out in toluene at 20-80 ^° C by sequential introduction into a solvent butadiene-1.3 to a concentration of 10-60 wt.% and components of the catalytic system based on the molar dosage of n-butyllithium 10-70 moles per ton of monomer and molar ratios potassium: lithium from 0.03 to 0.8 and a compound to lithium from 0.1 to 1.5.

When the polymerization temperature is lower than 20 ^o C, a decrease in the process speed is observed (quantitative polymer yield is achieved in a few days), and polymerization at a temperature of more than 80 ^o C requires special safety measures and equipment, as well as an increase in secondary reactions that degrade product quality.

 Limitations on the monomer concentration are associated with economic feasibility (lower) and process safety conditions, as well as a sharp increase in gelation reactions (upper).

 When the dosage of n-butyllithium is less than 10 mol per ton of monomer, the process speed decreases and the molecular weight of the polymer increases. The introduction of more than 70 mol per ton of monomer does not lead to significant changes in the properties of the polymer and the efficiency of the system, but requires special washing of it from catalyst residues.

 The conditions of the molar ratios of the compound and potassium to lithium are selected based on the objectives of the invention - the need to obtain more than 50% of 1,2-units in the polymer chain, maintaining high process speeds.

 After carrying out the polymerization of butadiene-1,3, an alcohol solution of an antioxidant (agidol-2) is introduced into the reaction mass, isolated by known methods (water degassing, followed by drying in an oven or on hot rollers, a rotary film evaporator, etc.).

The polymer is characterized by a Heppler dynamic viscosity at 50 ^° C. and a microstructure.

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

 The invention is illustrated by the following examples.

 Example 1 (prototype).

 850 g (977 ml) of toluene and 150 g (242 ml) of butadiene-1,3, toluene solutions of dimethyl ether are loaded into a 3-liter metal reactor equipped with devices for loading and unloading reagents, measuring temperature and pressure, a jacket for thermostating, stirring diethylene glycol (concentration 0.12 mol / l) and n-butyl lithium (concentration 0.2 mol / l) at the rate of 15 mol per ton of monomer and molar ratio of diglyme: lithium = 0.7.

 With constant stirring, they hold for 2 minutes and a toluene solution of potassium tetrahydrofurfurylate (0.3 mol / l concentration) is introduced based on the atomic ratio potassium: lithium = 0.15.

The process is carried out at 40 ^o C for 20 minutes. The polymer yield is 99 wt.%, And the content of 1,2-units is 67%, dynamic viscosity is 48 Pa • s.

 Example 2

 Carried out as described in example 1. 900 g (1034.4 ml) of toluene and 100 g (161.3 ml) of butadiene-1,3, toluene solutions of diethylene glycol diethyl ether (concentration 0.25 mol / l), n were introduced into the reactor. -butyl lithium (0.8 mol / L concentration) and potassium tetrahydrofurfurylate (0.64 mol / L concentration) based on the molar ratio of EMF: lithium = 0.7 and potassium: lithium = 0.03.

The process is carried out at a temperature of 20 ^o C for 15 minutes. The polymer yield is 99%, its dynamic viscosity is 5 Pa • s, and the content of 1,2 units is 61%.

 Example 3

 Carried out as described in example 1.

 400 g of toluene (459.8 ml) and 600 g (968 ml) of butadiene-1,3, toluene solutions of n-butyllithium (concentration 0.22 mol / l), tetrahydrofurfuryl alcohol ether (concentration 0.56 mol) are introduced into the reactor / l) and potassium diisobutylaluminate (concentration 0.65 mol / l) based on the molar ratio of the EMF: lithium = 1.5 and potassium: lithium = 0.8.

The process is carried out at a temperature of 80 ^o C for 18 minutes. The polymer yield is 100%, its dynamic viscosity is 43 Pa • s, and the content of 1,2 units is 74%.

 Example 4

 Carried out as described in example 1.

 700 g (804.6 ml) of toluene and 300 g (483.9 ml) of butadiene-1,3, toluene solutions of potassium tetrahydrofurfurylate (concentration 0.56 mol / l), n-butyllithium (concentration 0.45 mol) are introduced into the reactor / l), a mixture of diethylene glycol diethyl ether and tetrahydrofurfuryl alcohol ether (50:50 mol%) (concentration - 0.37 mol / l) based on the dosage of n-butyllithium 45 moles per ton of monomer and the molar ratio of EMF: lithium = 0 7, and potassium: lithium = 0.3.

The process is carried out at a temperature of 40 ^o C for 19 minutes. The polymer yield is 99 wt.%, Its dynamic viscosity is 77 Pa • s, and the content of 1,2 units is 66%.

Literature
1. Patent (a.s.) 1758042, 03.17.93, C 08 F 136/06, publ. BI N 32, 08/30/92.

 2. Patent 2017752, Russia, 04.17.91, C 08 F 136/04, 4/48, publ. BI N 15, 08/15/94.

 3. Patent 2082722, Russia, 05.17.95, C 08 F 136/06, publ. BI N 18, 06/27/97.

Claims (1)

A method for producing low molecular weight 1,2-polybutadiene by polymerization of butadiene-1,3 in a hydrocarbon solvent in the presence of a catalytic system consisting of n-butyllithium, an alkali metal alkoxide and an electron donor additive, characterized in that diethylene glycol diethyl ether and / or are used as an electron donor additive tetrahydrofurfuryl alcohol ether, potassium tetrahydrofurfurylate or potassium diisobutylaluminate is used as alkali metal alkoxide, and polymerization is carried out in toluene at 20 - 80 ^o C by sequentially introducing butadiene-1.3 into the solvent to a concentration of 10-60 wt.% And components of the catalytic system based on the dosage of n-butyllithium in the range of 10 - 70 mol per ton of monomer and molar ratios of potassium: lithium from 0, 03 to 0.8 and electron-donating additive: lithium from 0.1 to 1.5.

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