RU2440371C2 - Method of producing cis-1,4-polybutadiene - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: cis-1,4-polybutadiene is obtained in the medium of an aliphatic solvent, e.g. hexane, in the presence of a Ziegler-Natta catalyst system containing a neodymium salt solution, a chlorine-containing component and an organoaluminium compound, which are fed into a polymerisation cell separately. The chlorine-containing compound is fed fractionally into the first and the last reactor in amount of 30-40 wt % and 60-70 wt % respectively, and the remaining components - a complex containing the organoaluminium compound and the neodymium salt, are fed into the first reactor. That method of feeding components of the catalytic complex allows more flexible control of the polymerisation process and regulation of the quality of the polymer.

EFFECT: obtaining polybutadiene with low plasticity and cold flow, good combination of physical and mechanical characteristics, with good strength properties.

1 cl, 2 tbl, 3 ex

Description

The invention relates to a technology for producing cis-1,4-polybutadiene under the influence of Ziegler-Natta catalyst systems and can be used in the synthetic rubber industry for the production of tires and other rubber products.

Known methods for producing cis-1,4-polybutadiene under the action of catalytic systems based on compounds of rare-earth elements (REE) (AS No. 1539199, 01/30/90, C08F 4/42, 136/06).

There is a method according to which the polymerization of butadiene is carried out under the influence of a catalytic complex preformed in the presence of monomer, consisting of REE carboxylate, alkyl aluminum sesquichloride and organoaluminum compound (AOC) (Synthetic butadiene rubber SKD-6. TU 38.403778-93).

The disadvantage of this method is the relatively high consumption of catalyst, as well as high ductility and cold flow of polybutadiene.

Closest to the technical nature of the claimed invention is a method for producing cis-1,4-polybutadiene by solution polymerization in an aromatic or aliphatic solvent (toluene or hexane) in six reactors connected in series in the presence of a catalytic system comprising a solution of an organoaluminum compound, a neodymium salt and a chlorine-containing component moreover, a solution of a component of a catalytic complex containing neodymium carboxylate and isobutylaluminium sesquichloride is preformed in the presence of diene. The organoaluminum compound and the catalyst component containing neodymium carboxylate are fed separately to the first cascade reactor [Patent RU No. 2139298 C1, IPC 6 C08F 136/06, 4/54, 1999]. This method of separate feeding of the components of the catalytic complex allows to obtain cis-1,4-polybutadiene with reduced ductility and cold flow, more flexible control of the polymerization process and to regulate the quality of the polymer by changing the amount supplied to the battery of the organoaluminum compound AOS and the molar ratio AOC / REE = 20 / one.

The disadvantage of this method is the high cold flow and ductility and low conversion of 95% of the obtained polymer.

The objective of the invention is to develop a method for producing cis-1,4-polybutadiene with reduced ductility and cold flow and high physical and mechanical properties of vulcanizates.

The specified technical result is achieved by the fact that in the claimed method, the preparation of cis-1,4-polybutadiene is carried out in an aliphatic solvent, for example, in hexane, in the presence of a Ziegler-Natta catalyst system containing a solution of neodymium salt, a chlorine-containing component and an organoaluminum compound, which are fed into separate polymerisation battery of reactors. In this case, the chlorine-containing component is fed fractionally to the first and last reactor, with 30-40 wt.% To the first reactor, and 60-70 wt.% To the last reactor, and the remaining components of the catalyst system are fed to the first reactor. The chlorine-containing compound is fed by a separate feed line.

The method is as follows.

A mixture consisting of a solution of butadiene in an aliphatic solvent - hexane and a solution of the Ziegler-Natta catalyst system containing a solution of a neodymium salt, a chlorine-containing component and an organoaluminum compound are separately fed to a polymerization battery consisting of three series-connected reactors. In this case, neodymium chloride (REE) is used as the neodymium salt, and ethylaluminium sesquichloride (EASC) as the chlorine-containing compound. The organoaluminum compound is trizobutylaluminum (TIBA).

A solution of neodymium salt and an organoaluminum compound are fed into the first reactor together in the form of a complex, the chlorine-containing component is supplied separately and fractionally, with 30-40 wt.% In the first reactor and 60-70 wt.% In the last reactor.

The inventive method allows to obtain a polymer with reduced ductility and cold flow and high physical and mechanical characteristics of the vulcanizates.

A distinctive feature of the proposed method in comparison with the closest analogue is that the chlorine-containing component, ethylaluminium sesquichloride (EASC), is fed fractionally to the first and last reactors. In this case, 30-40 wt.% Is fed into the first reactor, and 60-70 wt.% Into the last reactor. The remaining components of the catalytic system, TIBA and REE, are fed into the first reactor.

The parameters of the process for producing cis-1,4-polybutadiene according to specific examples 1-3 are presented in table 1.

An example of a prototype.

The polymerization of butadiene in the presence of a catalytic system is carried out in six reactors connected in series, where 30 t / h of a charge, which is a 10% solution of butadiene (3 t / h) in hexane (27 t / h), are fed. At the same time, the components of the catalytic system are separately supplied to the first reactor: 419 l / h (90 mol / h) triisobutyl aluminum solution (TIBA) and 57.7 l / h (7.5 mol REE / h) preformed solution of neodymium carboxylate and alkylaluminium sesquichloride (AACX) in hexane. CHIBA / neodymium = 12/1. The conversion of the monomer in the sixth polymerizer 95%. (Patent RU No. 2139298 C1, IPC 6 C08F 136/06, 4/54, 1999)

Example 1. The polymerization of butadiene in the presence of a catalytic system is carried out in series-connected three reactors, which serves 30 t / h of the mixture, which is a 10% (wt.) Solution of butadiene (3 t / h) in hexane (27 t / h) and 120 kg / h of a catalytic system based on neodymium chloride, a solution of ethyl aluminum sesquichloride (EASC) and triisobutyl aluminum (TIBA) in hexane. The chlorine-containing component (EAC) is supplied fractionally, with the first 40 wt.% (0.0296 kmol / h - molar flow rate; 7.32 kg / h - mass flow rate) and the last apparatus 60 wt.% (0.0324 kmol / h - molar flow rate; 8.06 kg / h - mass flow rate). The molar ratio of chlorine / neodymium in the catalytic system for the reactors: in the first and second reactor is 1.6 / 1, in the third 4/1. The conversion of the monomer in the third polymerizer is 98–99%.

Example 2. The polymerization of butadiene in the presence of a catalytic system is carried out in series-connected three reactors, which serves 30 t / h of the mixture, which is a 10% (wt.) Solution of butadiene (3 t / h) in hexane (27 t / h) and 120 kg / h of a catalytic system based on neodymium chloride, a solution of ethyl aluminumsexvichloride (EACC) and triisobutylaluminum (TIBA) in hexane. The chlorine-containing component (EAC) is supplied fractionally, with the first 30 wt.% (0.033 kmol / h - molar flow rate; 8.16 kg / h - mass flow rate) and the last apparatus 70 wt.% (0.051 kmol / h - molar flow rate; 12.72 kg / h - mass flow rate). The molar ratio of chlorine / neodymium in the catalytic system for the reactors: in the first and second reactors, 1.8 / 1, in the third 6/1. The conversion of the monomer in the third polymerizer is 98–99%.

Example 3. The polymerization of butadiene in the presence of a catalytic system is carried out in series-connected three reactors, which serves 30 t / h of the mixture, which is a 10% (wt.) Solution of butadiene (3 t / h) in hexane (27 t / h) and 120 kg / h of a catalytic system based on neodymium chloride, a solution of ethyl aluminumsexvichloride (EACC) and triisobutylaluminum (TIBA) in hexane. The chlorine-containing component (EAC) is supplied fractionally, with the first 90 wt.% (0.036 kmol / h - molar flow rate; 8.88 kg / h - mass flow rate) and the last apparatus 10 wt.% (0.003 kmol / h - molar flow rate; 0.84 kg / h - mass flow rate). The molar ratio of chlorine / neodymium in the catalytic system for the reactors: in the first and second reactors 2/1 in the third 2.22 / 1. The conversion of the monomer in the third polymerizer 93 ÷ 96%.

From the above examples it is seen that the most optimal mode of obtaining cis-1,4-polybutadiene by the claimed method is a fractional supply of a chlorine-containing component (EAC) to the first and last reactors in a ratio of 30-40 wt.% To 60-70 wt.%.

Examples 1-3 show that the proposed method has several advantages and makes it possible to obtain cis-1,4-polybutadiene by solution polymerization in a hexane solvent in series reactors in the presence of a neodymium catalyst system with reduced ductility and cold flow and a high set of physicomechanical characteristics vulcanizates through a significant reduction in the cost of well-known technologies for the synthesis of SKDN.

The results of physical and mechanical tests of cis-1,4-polybutadiene samples obtained by the present method and the prototype method, as well as comparative characteristics are presented in table 2.

Thus, the proposed method makes it possible to obtain cis-1,4-polybutadiene under the influence of a neodymium-containing catalyst system with reduced ductility, high physicomechanical parameters of vulcanizates at a lower catalyst consumption. The method of separately supplying the components of the catalytic complex also allows more flexible control of the polymerization process and the quality of the polymer by changing the amount supplied to the battery of the organoaluminum compound (AOC) and the molar ratio of AOC / REE.

Claims (1)

A method of producing cis-1,4-polybutadiene by solution polymerization in an aliphatic solvent, for example, hexane, in the presence of a Ziegler-Natta catalyst system comprising a solution of a neodymium salt, a chlorine-containing component and an organoaluminum compound, with a separate supply of individual components, characterized in that the salt solution neodymium and the organoaluminum compound are fed together as a complex into the first reactor, the chlorine-containing component is fed separately and fractionally, with 30-40 wt.% in the first reactor and 60-70 in the last reactor wt.%.