JPH0363566B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a reinforced polybutadiene rubber comprising 5 to 30% by weight of boiling n-hexane insolubles and 95 to 70% of boiling n-hexane solubles.

Cis-1,4 polybutadiene obtained by polymerizing 1,3-butadiene in the presence of a cis-1,4 polymerization catalyst is produced in large quantities as a raw material for tires and other rubber products. The physical properties of rubber products obtained from cis-1,4 polybutadiene are superior to products made from natural rubber, especially in terms of good impact resilience, low calorific value, and superior abrasion resistance. This superiority is one of the reasons why cis-1,4 polybutadiene is used in large quantities. However, cis-1,4 polybutadiene has the disadvantage that the rubber products obtained therefrom have low tear strength and low flex crack growth resistance.

As a polybutadiene rubber that improves the drawbacks of this cis-1,4 polybutadiene, 1,3-
Polymerizing butadiene in the presence of a cis-1,4 polymerization catalyst to produce cis-1,4 polybutadiene;
Subsequently, a new polybutadiene obtained by polymerizing 1,3-butadiene in the presence of a 1,2 polymerization catalyst was proposed (Japanese Patent Publication No. 49-17666).

The above publication describes an experimental example of producing polybutadiene which, when vulcanized, has high tear strength and excellent flex crack growth resistance.

However, the method for producing polybutadiene described in the above publication uses carbon disulfide as a component of the 1,2 polymerization catalyst, and adds this carbon disulfide to the 1,2 polymerization tank. After the polymerization reaction is completed, 1,3-butadiene and an inert organic solvent are added.
In particular, it is difficult to completely separate 1,3-butadiene by distillation, and carbon disulfide is difficult to handle, making it difficult to put the production of polybutadiene into practical use.

Therefore, the inventors completed this invention as a result of intensive research aimed at providing a continuous production method for polybutadiene rubber having the above-mentioned excellent physical properties.

That is, the present invention provides a method for cis-1,4 polymerization of 1,3-butadiene in an inert organic solvent and then 1,2 polymerization, which comprises: (a) combining 1,3-butadiene and an inert organic solvent; (b) adjusting the concentration of water in the obtained solution of 1,3-butadiene in an inert organic solvent _; A halogen-containing compound _represented by An organoaluminum compound and a cobalt compound, which is another component of the cis-1,4 polymerization catalyst, are added, and the resulting solution is stirred and mixed to produce cis-1,4 polybutadiene. A 1,2 polymerization catalyst obtained from a cobalt compound, an organoaluminum compound represented by the general formula AlR ₃ (where R is the same as above), and carbon disulfide is present in the polymerization reaction mixture. ,
(e) polymerizing 1,3-butadiene to produce a final polybutadiene rubber consisting of 5 to 30% by weight of boiling n-hexane insolubles and 95 to 70% of boiling n-hexane solubles; After adding a polymerization terminator to the reaction mixture, the solid content of polybutadiene rubber is separated and obtained, and (f) from the mixture containing the remaining unreacted 1,3-butadiene, an inert organic solvent, and carbon disulfide, 1,3-butadiene and an inert organic solvent are obtained as a fraction by distillation, and carbon disulfide is separated and removed by adsorption separation treatment or carbon disulfide adduct separation treatment, and carbon disulfide is substantially removed. The present invention relates to a method for producing reinforced polybutadiene rubber, characterized in that 1,3-butadiene and an inert organic solvent, which do not contain 1,3-butadiene, are recycled to the step (a).

In the method of this invention, in the first step (a), 1,3-butadiene and an inert organic solvent are preferably added to the 1,3-butadiene and the inert organic solvent based on the total amount of 1,3-butadiene and the inert organic solvent. They are mixed in such a way that the ratio of the two components is 3% by weight or more, particularly in the range of 3 to 40% by weight.

As the inert organic solvent, cis-1,4
There are no particular restrictions as long as the organic solvent can dissolve polybutadiene, but aromatic hydrocarbons such as benzene, toluene, and kyrylene, aliphatic hydrocarbons such as n-heptane and n-hexane, and alicyclic solvents such as cyclohexane and cyclopentane are used. group hydrocarbons, and their halides, such as methylene chloride, chlorobenzene, and the like.

In the method of this invention, in step (b),
The concentration of water in the liquid mixture obtained as described above is adjusted. In the method of the present invention, if a predetermined amount of water already exists in the mixed solution, it is possible to proceed to the next step (c). The water is in the mixture 1.
It is preferably contained in a concentration of 0.5 to 5 mmol. As a method for adjusting the concentration of water, a method known per se can be employed.

In the method of the present invention, after adjusting the concentration of water in the mixture of 1,3-butadiene and an inert organic solvent, preferably after cooling the mixture to 10°C or less, in step (c), The above general formula AlR _o
A halogen-containing organoaluminum compound represented by X _3-o and a cobalt compound are added, and the resulting solution is stirred and mixed to polymerize 1,3-butadiene to produce cis-1,4 polybutadiene.
In the method of this invention, it is necessary to adjust the water concentration in advance as described above before adding the halogen-containing organoaluminum compound and cobalt compound to the polymerization system.
This makes it possible to polymerize 1,3-butadiene to obtain cis-1,4 polybutadiene in high yield.

Examples of the halogen _- containing organoaluminum compound represented by the general formula AlR _o Examples include aluminum sesquichloride.

The cobalt compound, which is another component of the cis-1,4 polymerization catalyst, may be of any type as long as it is soluble in the inert organic solvent used. for example,
Examples of such cobalt compounds include cobalt β-diketone complexes such as cobalt () acetylacetonate and cobalt () acetylacetonate, cobalt β-keto acid ester complexes such as cobalt acetoacetate ethyl ester complex, and cobalt octoacetate complexes. Examples include cobalt salts of organic carboxylic acids having 6 or more carbon atoms such as cobalt ester, cobalt naphthenate, and cobalt benzoate, and cobalt halide complexes such as cobalt chloride pyridine complexes and cobalt chloride ethyl alcohol complexes.

In the method of this invention, the amount of the cis-1,4 polymerization catalyst used is such that the halogen-containing organoaluminum compound is
It is preferred that the amount of cobalt compound is at least 0.1 mmol, especially from 0.5 to 50 mmol, and at least 0.001 mmol, especially at least 0.005 mmol. Further, the molar ratio (Al/Co) of the halogen-containing organoaluminum compound to the cobalt compound is preferably 5 or more, particularly 15 or more.

In the method of this invention, the polymerization temperature for cis polymerization is preferably -20 to 80°C, particularly 5 to 50°C, the polymerization pressure may be normal pressure or increased pressure, and the polymerization time (average residence time in the cis polymerization tank Although the time varies depending on the catalyst concentration, monomer concentration, polymerization temperature, etc., it is usually preferably in the range of 10 minutes to 10 hours. Further, cis polymerization is carried out by stirring and mixing the solution in a cis polymerization tank. The polymerization tank used for cis polymerization is a polymerization tank equipped with a high viscosity liquid stirring device, for example,
The device described in Japanese Patent No. 2645 can be used.

The above cis polymerization has a cis-1,4 structure content of 90
% or more, especially 95% or more, and cis-1,4 polybutadiene having an intrinsic viscosity [η] of toluene at 30°C of 1.5 to 8, particularly 1.5 to 5 is preferably produced. [η] 30°C In order to adjust the toluene to an appropriate value, known molecular weight regulators such as non-conjugated dienes such as cyclooctadiene and allene,
Alternatively, alpha-olefins such as butene-1 can be used. Additionally, known gel inhibitors can be used to suppress the formation of gel during cis polymerization.

In the method of this invention, in step (d),
Step (c): A 1,2 polymerization catalyst obtained from a cobalt compound, an organoaluminium compound represented by the general formula _AlR3 , and carbon disulfide is present in the polymerization reaction mixture obtained in the cis polymerization step. Let me,
Polymerize 1,3-butadiene to obtain a boiling n-hexane insoluble content of 5 to 30% by weight and a boiling n-hexane soluble content of 95% by weight.
A final polybutadiene rubber consisting of ~70% by weight is produced.

Examples of the organoaluminum compound represented by the general formula AlR ₃ that is the aluminum component of the 1,2 polymerization catalyst include triethylaluminum, trimethylaluminum, triisobutylaluminum, triphenylaluminum, and the like.

Examples of the cobalt component of the 1,2 polymerization catalyst include the same cobalt compounds as mentioned above as one of the components of the cis-1,4 polymerization catalyst.

Carbon disulfide, which is a component of the 1,2 polymerization catalyst, is not particularly limited, but preferably contains no water.

The amount of the 1,2 polymerization catalyst used varies depending on the type and combination of each catalyst component and the polymerization conditions, but the cobalt compound is 0.005 mmol or more, particularly 0.01 to 5 mmol, per mole of 1,3-butadiene. Organoaluminum compound is 0.1 mmol or more,
It is particularly preferable that the amount of carbon disulfide is 0.5 to 50 mmol, and 0.001 mmol or more, especially 0.01 to 10 mmol.

In the method of this invention, if the cobalt compound in the cis polymerization catalyst and the cobalt compound in the 1,2 polymerization catalyst are the same, the amount of cobalt compound required for the 1,2 polymerization is also added during the cis polymerization. However, it is also possible to select conditions in which only the organoaluminum compound is added during the 1,2 polymerization.

In the method of this invention, the polymerization temperature for 1,2 polymerization is preferably -20 to 80°C, particularly 5 to 50°C, the polymerization pressure may be either normal pressure or increased pressure, and the polymerization time is 10 minutes to 10 minutes. A time range is preferred. Also,
The 1,2 polymerization is carried out by stirring and mixing the solution in a 1,2 polymerization tank. As the polymerization tank used for 1,2 polymerization, the viscosity of the polymerization reaction mixture becomes higher during the 1,2 polymerization, and the polymer tends to adhere to the inside of the polymerization tank, so the polymerization tank used is as described in Japanese Patent Publication No. 1982-2645. It is preferable to use a polymerization tank equipped with a scraping member.

During 1,2 polymerization, the concentration of 1,3-butadiene in the polymerization system is preferably 3 to 35% by weight.

In the method of this invention, in step (e),
Step (d): A polymerization reaction mixture containing the polybutadiene rubber obtained in the 1,2 polymerization step, unreacted 1,3-butadiene, carbon disulfide, a cobalt compound, an organoaluminum compound, and an inert organic solvent. , preferably into a polymerization stop tank, and after adding a polymerization stopper to this polymerization reaction mixture to stop the polymerization, the solid content of polybutadiene rubber is separated and obtained.

As the polymerization terminator, the above-mentioned general formula
Any compound that reacts with the halogen _- containing organoaluminum compound represented by _{AlR o} Inorganic acids such as acetic acid, organic acids such as benzoic acid, monoethanolamine, ammonia, phosphite esters such as tris(nonylphenyl) phosphite, and hydrogen chloride gas. Particularly preferred polymerization terminators include phosphorous esters.
These may be added alone to the polymerization reaction mixture, or may be added as a mixture with water, alcohol, or an inert organic solvent.

After stopping the polymerization of 1,3-butadiene, a precipitant such as methanol is added to the polymerization reaction mixture, or volatile matter is evaporated and removed by flashing (by or without blowing in steam).
The solid content of the polymer is precipitated and separated and dried to obtain polybutadiene rubber. It is preferable to add an anti-aging agent to the polybutadiene rubber by adding the anti-aging agent to a polymerization reaction mixture after stopping the polymerization of 1,3-butadiene or to a slurry of the polybutadiene rubber.

The polybutadiene rubber obtained by the method of this invention has a boiling n-hexane insoluble content of 5 to 30% by weight and a boiling n-hexane soluble content of 95 to 70% by weight.
The melting point of the boiling n-hexane insoluble matter is 180~
The temperature is 215℃.

In the method of this invention, in step (f),
From the mixture containing unreacted 1,3-butadiene, an inert organic solvent, and carbon disulfide (usually referred to as a recovery solvent), which is the residue obtained by separating the solid content of polybutadiene rubber from the polymerization reaction mixture,
1,3-butadiene and an inert organic solvent are obtained as a fraction by distillation, and carbon disulfide is separated and removed by carbon disulfide adsorption separation treatment or carbon disulfide adduct separation treatment. Then, 1,3-butadiene substantially free of carbon disulfide and an inert organic solvent are recovered.

Carbon disulfide is separated and removed from a mixture containing the above three components by adsorption separation treatment using a basic anion exchange resin such as an ion exchange resin containing an amino group, or alternatively, carbon disulfide is separated and removed by reaction with carbon disulfide. Nitrogen-containing compounds that form adducts that are insoluble in inert organic solvents, water-soluble adducts, or have a boiling point significantly higher than that of 1,3-butadiene and the inert organic solvent are combined with carbon disulfide. Carbon disulfide is separated and removed by a carbon disulfide adduct separation treatment in which the resulting adduct is separated from the solution by a method known per se, and then distilled to remove carbon disulfide, which essentially contains carbon disulfide. The 1,3-butadiene and inert organic solvent that are not present can be recovered as a fraction.

Further, from a mixture containing the three components, the three components are recovered as a fraction by distillation,
By separating and removing carbon disulfide from this fraction by the aforementioned adsorption separation or carbon disulfide adduct separation treatment, 1,3-butadiene containing substantially no carbon disulfide and inert organic The solvent can be recovered.

Or, from a mixture containing the three components mentioned above,
By distillation, 1,3-butadiene containing carbon disulfide is obtained as a fraction, and an inert organic solvent that does not substantially contain carbon disulfide is obtained as a residue, and from the fraction, the above-mentioned adsorption separation is performed. Alternatively, carbon disulfide can be separated and removed by carbon disulfide adduct separation treatment, and carbon disulfide can also be removed by distillation from the above-mentioned pot residue to obtain an inert organic solvent as a fraction. Substantially free 1,3-butadiene and inert organic solvent can be recovered.

The adsorption/separation treatment of carbon disulfide using the basic anion exchange resin may be carried out by a batch method or by a flow method, at a temperature of 5 to 60°C.
It is preferable to carry out the reaction for 1 to 60 minutes (residence time). As the basic anion exchange resin, commonly available weakly basic anion exchange resins such as Amberlite IR-45, Diaion WA-21, Dowex 3, and Durite A-7 can be used. When processing by the batch method, the amount of basic anion exchange resin depends on the amount of solution being treated.
0.1 to 10 parts by volume per 100 parts by volume is preferred. Also,
When processing using the circulation method, the space velocity (Space
Velocity) [the value obtained by subtracting the flow rate per hour (m ³ /hr) by the volume of the filler (m ³ ), usually expressed without a unit] is preferably 2 to 15. The basic anion exchange resin is preferably swollen with an inert organic solvent before treatment. In addition, when removing carbon disulfide using a weakly basic anion exchange resin, trace amounts of
Since H ₂ S is produced as a by-product, the solution treated with a weakly basic anion exchange resin must be further washed with water, or H ₂ S must be removed using a strongly basic anion exchange resin such as Diaion PA-316. is preferable.

In addition, in the above-mentioned carbon disulfide adduct separation treatment, 1 to 20 mol of a nitrogen-containing compound is added to the solution to be treated per 1 mol of carbon disulfide contained in the solution, and the temperature is 5 to 60°C. It is preferable to carry out the reaction by stirring and mixing for 5 to 120 minutes to react the carbon disulfide and the nitrogen-containing compound, and then separating the reaction product from the solution. The solution containing the reaction product is washed with water, distilled,
The reaction product of carbon disulfide and the nitrogen-containing compound may be separated from the solution by filtration or centrifugation. Examples of the nitrogen-containing compounds include melamine, guanidine, ethylenediamine, 1,6-hexamethylenediamine, 1,12-dodecamethylenediamine, diethylenetriamine, diethylamine, n-octylamine, n-lauroamine, di-n-butylamine, and the like. Aliphatic amines: aniline, 2,4-diaminophenol, 2,4-diaminotoluene, 2,6-diaminotoluene, 2,
2'-diaminodiphenylmethane, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 3,5
-diaminobenzoic acid, p-diaminoazobenzene, 4,4-diaminodiphenylamine, benzidine, 3,3-diaminobenzidine, 1,2,
Examples include aromatic amines such as 4,5-tetraaminobenzene, p,p'-diaminodiphenyl oxide, piperidine, and benzylamine, and alicyclic amines such as cyclohexylamine and cyclopentylamine.

The 1,3-butadiene substantially free of carbon disulfide and the inert organic solvent recovered by the above method can be recycled to the above step (a).

The 1,3-butadiene substantially free of carbon disulfide and the inert organic solvent recycled as described above are used in admixture with fresh 1,3-butadiene.

In addition, basic anion exchange resin that has adsorbed carbon disulfide can be washed with acid and then washed with alkali to recover carbon disulfide and regenerate the basic anion exchange resin. After purification, it can be recycled to step (f) above.

Hereinafter, the flow sheet of FIG. 1 showing an embodiment in which an inert organic solvent such as benzene having a boiling point higher than the boiling point of 1,3-butadiene is used as an inert organic solvent when carrying out the method of the present invention will be described. This invention will be further explained using the following. However, the scope of this invention is not limited to the following description.

In FIG. 1, fresh 1,3-butadiene is fed from tank 1 through conduit
- Butadiene and the purified recovered solvent (a mixture of 1,3-butadiene and an inert organic solvent) fed through the conduit 21 from the purified recovered solvent tank 2 are mixed in the mixer 3. Obtained 1,
The benzene solution of 3-butadiene is led via conduit 22 to mixer 4 . A suitable amount of water is supplied to the benzene solution of 1,3-butadiene through conduit 23. After the benzene solution of 1,3-butadiene and water are uniformly mixed in the mixer 4, the conduit 2
4 and then supplied to a cis-1,4 polymerization reaction tank 5. In addition, the cis-1,4 polymerization reaction tank 5 includes:
Conduit 25 supplies the halogen-containing organoaluminum compound, conduit 26 supplies the molecular weight regulator such as cyclooctadiene, and conduit 27 supplies the dilauryl-containing compound.
An antigel agent such as 3,3'-thiodipropionate and a cobalt compound are respectively supplied through conduit 28. In the cis-1,4 polymerization reaction tank 5, the solution is stirred and mixed to produce cis-1,4 polybutadiene.

The polymerization reaction mixture obtained in the cis-1,4 polymerization reaction tank 5 is supplied to the 1,2 polymerization reaction tank 6 via a conduit 29. Further, to the 1,2 polymerization reaction tank 6, a cobalt compound is supplied from a conduit 30, an organoaluminum compound represented by the general formula AlR ₃ is supplied from a conduit 31, and carbon disulfide is supplied from a conduit 32. Although not shown, an organoaluminum compound of the general formula AlR ₃ and/or carbon disulfide may be fed into conduit 29).
In the presence of a 1,2 polymerization catalyst obtained from these cobalt compounds, an organoaluminum compound represented by the general formula _AlR3 , and carbon disulfide, the mixture is stirred to polymerize 1,3-butadiene, and boiling n-hexane A final make-up polybutadiene rubber is produced consisting of 5-30% by weight insolubles and 95-70% by weight boiling n-hexane solubles. When 1,3-butadiene is polymerized in the 1,2 polymerization reaction tank 6, polymers that are insoluble in the inert organic solvent precipitate and the polymerization reaction mixture becomes highly viscous. A polymerization reaction tank equipped with a stirrer and a scraping member is preferably used.

The polymerization reaction mixture obtained in the 1,2 polymerization reaction tank 6 is supplied to a polymerization termination tank 40 via a conduit 39. Meanwhile, a polymerization terminator is supplied to the polymerization reaction mixture from the conduit 34 in the polymerization termination tank 40 to terminate the polymerization of 1,3-butadiene. The mixture whose polymerization has been stopped is supplied to the reinforced polybutadiene rubber separator 7 through the conduit 35, and the solid content of the reinforced polybutadiene rubber 8 is separated from the polymerization reaction mixture.
and a liquid mixture containing unreacted 1,3-butadiene, an inert organic solvent and carbon disulfide.

The remaining liquid mixture after the reinforced polybutadiene rubber 8 as a solid content is separated by the reinforced polybutadiene rubber separator 7 is passed through the conduit 36 to be subjected to carbon disulfide adsorption separation treatment or carbon disulfide adduct separation treatment. It is supplied to the container 9. The treatment device 9 separates and removes carbon disulfide 10 from the liquid mixture.

The liquid mixture containing 1,3-butadiene and an inert organic solvent from which carbon disulfide has been removed by a treatment device 9 such as carbon disulfide adsorption separation treatment or carbon disulfide adduct separation treatment is transferred to a conduit 37. It is supplied to the distillation apparatus 11 (which may be one distillation column or two distillation columns). Distillation device 11
1, which does not substantially contain carbon disulfide by
3-butadiene and an inert organic solvent are separated,
These are fed via conduit 38 to purified recovered solvent tank 2 . Further, high-boiling substances 12 are separated and removed from the distillation apparatus 11.

According to the method of the present invention, reinforced polybutadiene rubber can be continuously produced which exhibits excellent physical properties when made into a final rubber product.

Next, examples will be shown. In the implementation order, the boiling n-hexane insoluble content of reinforced polybutadiene rubber is defined as 2g of reinforced polybutadiene rubber mixed with 200ml of n-hexane.
- After dissolving most of it in hexane at room temperature, the insoluble matter was extracted using a Soxhlet extractor for 4 hours, the extracted residue was vacuum dried, and its weight was accurately weighed. In addition, the boiling n-hexane soluble content is
This was determined by evaporating n-hexane from the n-hexane solution obtained above and the extract using a Soxhlet extractor, vacuum drying, and accurately weighing the weight. In addition, the n-hexane soluble content and cis-
The cis-1,4 structure content of polybutadiene after 1,4 polymerization was measured by infrared absorption spectroscopy (IR), and the 1,2-structure content of the n-hexane insoluble portion was measured by nuclear magnetic resonance spectroscopy (NMR). The melting point of the n-hexane insoluble component was determined by the peak temperature of the endothermic curve measured using a digital differential calorimeter (DSC).

In addition, the n-hexane soluble content of the supplemented polybutadiene rubber and the intrinsic viscosity [η] of the polybutadiene after cis-1,4 polymerization are the values measured in toluene at 30°C, and the n-hexane insoluble content of the reinforced polybutadiene rubber. The reduced viscosity η _sp /C is the value measured in tetralin at 135°C.

Further, the content of carbon disulfide in the solution was measured and calculated using gas chromatography equipped with a flame photometric detector using Chromosolve 102 as a filler.

Example 1 containing 23.7% by weight of 1,3-butadiene
Water was removed from the benzene solution of 3-butadiene using a dehydration tower, water was added to the resulting solution at a rate of 40 mg (2.2 mmol), and the mixture was mixed and dissolved in a mixing tank equipped with stirring blades. After cooling this solution to -3°C,
A stainless steel autoclave with an internal volume of 20 °C and a ribbon-type stirring blade was equipped with a jacket for temperature control on the outer cylinder, and a cis-1,4 polymerization tank in which a CaCl ₂ aqueous solution at -10 °C was circulated through the jacket was heated at a rate of 50 °C per hour. 25.3g of diethylaluminum monochloride and 1,5-cyclooctadiene per hour.
60.0g, TPL (dilauryl-3,3'-thiodipropionate) 7.0g/hour, cobalt octoate 260mg/hour, 1,3 -butadiene was cis-1,4 polymerized. The amount of polybutadiene produced per hour by this cis-1,4 polymerization is 3.22
Kg, and this polybutadiene is cis-1,4
The structural content was 96% or more, [η] was 1.8, and the gel content measured using a 200-mesh wire mesh was 0.02%.

The polymerization reaction mixture obtained in the cis-1,4 polymerization tank was transferred to a polymerization tank of the same type as the cis-1,4 polymerization tank (1,
2 polymerization tank) at a rate of 50% per hour,
27.3 g/h of triethylaluminum, 842 mg/h of cobalt octoate, 840 mg/h of carbon disulfide.
1 and 2 polymerizations were carried out at a polymerization temperature of 40° C. and an average residence time of 24 minutes. The obtained polymerization reaction mixture was continuously supplied to a mixing tank equipped with stirring blades, and a small amount of tris(nonylphenyl)phosphite and then water were mixed therein to stop the polymerization. This mixture is added to a solvent evaporation tank (steam stripper) equipped with stirring blades every hour.
120, hot water and 4 Kg/cm ² G of saturated steam were fed, the mixture was dispersed in the hot water and the solvent was evaporated.

After extracting the slurry from the evaporation tank and separating water and dispersed polybutadiene crumbs, the crumbs were vacuum-dried at room temperature to obtain reinforced polybutadiene rubber.

Polymerization was carried out continuously for 14 hours, and an average weight of 3.62 kg of reinforced polybutadiene rubber was obtained per hour of polymerization time. This reinforced polybutadiene rubber has a boiling n-hexane insoluble content of 11.1%, a boiling n-hexane insoluble content having a melting point of 205°C, and η _sp /C of 2.1 (dl/
g), the 1,2-structure content was 93.1%, the boiling n-hexane soluble content had a cis-1,4 structure content of 96.9%, and [η] was 1.8.

After the polymerization reaction was completed, a benzene solution of 1,3-butadiene was flowed at a rate of 50 per hour for 30 minutes, and the polymer adhering to the stirring blades and inner walls of the polymerization tank was scraped off and dried under vacuum to obtain the adhering polymer. Ta. The amount of attached polymer is
The amount was 18 g (of which 3 g was gel content), and 99 g in the 1st and 2nd polymerization tanks.

On the other hand, the solvent evaporated from the evaporation tank was cooled and condensed to separate into an aqueous phase and a solvent phase, and 1,3-butadiene and benzene were recovered from the obtained solvent (referred to as recovered solvent) as follows. .

Recovery solvent containing 16.1% by weight of 1,3-butadiene and 12.5mg/% of carbon disulfide.
300 in a packed tower filled with basic anion exchange resin (Diaion WA-20) (packing height 70 cm,
The mixture was then passed through a packed tower (packing height 30 cm, packed tower inner diameter 10 cm) filled with a strongly basic anion exchange resin (Diaion PA-316) at a rate of 50% per hour at 15 to 20°C. After carbon disulfide was removed by distillation, high-boiling substances were removed by distillation to obtain a polymerization solvent, and the polymerization solvent was reused. Regeneration of the anion exchange resin was performed by conventional HCl and NaOH washes. Through the above treatment, more than 98% of carbon disulfide in the recovered solvent was removed, and 1,3-butadiene and benzene substantially free of carbon disulfide were recovered.

On the other hand, 65 g of hexane methylene diamine was added to the recovery solvent 300 containing 16.1% by weight of 1,3-butadiene and 12.5 mg of carbon disulfide.
was added, and the solution was stirred and mixed at room temperature (approximately 20°C) for 50 minutes. Then a 1% aqueous solution of sodium hydroxide90
After stirring and mixing vigorously, the mixture was allowed to stand, and the aqueous phase was separated and removed. After adding 90% water to the solvent part and stirring and mixing, the mixture was allowed to stand, and the aqueous phase was separated and removed twice for washing with water. High-boiling substances were removed from the solvent portion by distillation and reused as a polymerization solvent.

Through the above treatment, carbon disulfide in the recovered solvent was reduced to 95%.
% or more was removed and 1,3-butadiene and benzene substantially free of carbon disulfide were recovered.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing an embodiment in which an inert organic solvent having a boiling point higher than that of 1,3-butadiene, such as benzene, is used as an inert organic solvent in carrying out the method of the present invention. It is a schematic diagram. 1; fresh 1,3-butadiene tank,
2; Purified recovery solvent tank, 3, 4; Mixer, 5; Cis-1,4 polymerization reaction tank, 6; 1,2 polymerization reaction tank, 7; Reinforced polybutadiene rubber separation device, 8; Reinforced polybutadiene rubber, 9; treatment device for carbon disulfide adsorption separation treatment or carbon disulfide adduct separation treatment, 10; carbon disulfide, 11; distillation device, 12; high boiling point substance, 20 to 38; conduit, 40;
Polymerization stop tank.

Claims (1)

[Claims] 1 cis-1,4 polymerization of 1,3-butadiene,
Then, in the method of 1,2 polymerization, (a) 1,3-butadiene and an inert organic solvent are mixed, (b) the concentration of water in the obtained inert organic solvent solution of 1,3-butadiene is determined. (c) Then, one component of the cis-1,4 polymerization catalyst having the general formula _{AlR o} , X is a halogen atom, and n is a number from 1.5 to 2) and a cobalt compound, which is another component of the cis-1,4 polymerization catalyst, are simultaneously added. Alternatively, a cobalt compound is added within 1 minute after addition of the halogen-containing organoaluminum compound, and the resulting solution is stirred and mixed to produce cis-1,4 polybutadiene; (d) the resulting polymerization reaction A 1,2 polymerization catalyst obtained from a cobalt compound, an organoaluminum compound represented by the general formula AlR ₃ (where R is the same as above), and carbon disulfide is present in the mixed liquid,
(e) polymerizing 1,3-butadiene to produce a final polybutadiene rubber consisting of 5 to 30% by weight of boiling n-hexane insolubles and 95 to 70% of boiling n-hexane solubles; After adding a polymerization terminator to the reaction mixture, the solid content of polybutadiene rubber is separated and obtained, and (f) from the mixture containing the remaining unreacted 1,3-butadiene, an inert organic solvent, and carbon disulfide, 1,3-butadiene and an inert organic solvent are obtained as a fraction by distillation, and carbon disulfide is separated and removed by adsorption separation treatment or carbon disulfide adduct separation treatment, and carbon disulfide is substantially removed. 1. A method for producing reinforced polybutadiene rubber, characterized in that 1,3-butadiene and an inert organic solvent that do not contain carbon are recycled to the step (a).