JP5939333B1 - Method for producing diene rubber - Google Patents

Abstract

The present invention provides a method for producing a high-quality and high-productivity diene rubber that reduces coloring over time and exhibits excellent activity by an industrially simple method, and a diene rubber obtained thereby. A method for producing a diene rubber includes a step of aging water and organoaluminum in a temperature range of −30 to 17 ° C. from the start of ripening to the end of ripening before polymerizing the diene monomer. This is a method for producing a diene rubber that does not color with time. [Selection figure] None

Description

  The present invention relates to a method for producing a non-colored diene rubber which prevents the coloration with time that occurs with conventional diene rubbers, and a diene rubber obtained thereby.

  In general, diene rubbers often add many compounds such as various catalysts, promoters, and stabilizers in the production process. In particular, these additives are essential because the stability of the product is achieved by adding stabilizers. However, when there are many kinds and amounts of additives, side effects such as coloring and odor often occur, and unexpected problems may occur.

  In particular, when coloring occurs, there is often a big problem regarding applications in which transparency is required for products and applications in which a desired color is desired, and many solutions have been attempted so far.

  For example, in Patent Document 1, when a chloroprene polymer is produced, coloring is prevented by using diethylhydroxylamine and a phenolic anti-aging agent in combination as a polymerization terminator.

  Moreover, in patent document 2, by superposing | polymerizing 1 or more types of phenolic compounds after superposition | polymerization of a butadiene rubber, it adjusts so that pH value is the range of 4-11, and oxygen content may be 0-0.3 ppm. , Providing stable and colorless polybutadiene rubber.

  Furthermore, in the prior art document 3, at the time of polymerizing, one or more compounds selected from the group consisting of an arylphosphine compound and a silazane compound are added to the blend consisting of an antioxidant or a polymerization inhibitor. In order to prevent coloring.

  However, in any coloring prevention method, a compound is often added to the additive used in the conventional production process, and the production process is more complicated, and it is not necessarily advantageous in terms of cost.

  Therefore, the inventors have improved the coloring by controlling the ratio between the organic aluminum and the antioxidant as shown in Patent Document 4. In addition, as shown in Patent Document 5, a manufacturing method having excellent coloration with time has been invented by optimizing the aging time of organic aluminum and water.

Japanese Patent Laid-Open No. 06-345832 Special table 2003-535926 JP 2009-249308 A JP 2011-195632 A JP 2011-201972 A

  The inventors of the present invention have so far reduced coloring over time by the methods of Patent Documents 4 and 5 described above, but there has been a demand for further improvement. In the examination so far, in order to compare the experimental conditions under a constant condition, the aging temperature was made uniform at 20 ° C. and the comparison was made by changing the aging time. For example, in Example 1 of Patent Document 5, water was added to the raw material mixed solution, and after stirring and dissolving, the temperature was lowered to 10 ° C., and then organoaluminum was added. Organic aluminum and water rise in temperature due to an exothermic reaction after contact. Further, during the aging, the temperature rises due to the influence of the outside air temperature. In addition to these temperature increases, aging times have been compared under constant control at 20 ° C. by using a heat source such as hot water and ice water and a refrigerant. This 20 ° C. was set because it was easy to prepare all year round.

  Furthermore, in laboratory experiments, the temperature can be easily increased or decreased to ensure the same conditions. However, in plants that manufacture synthetic rubber industrially, the raw material butadiene and solvent are distilled and reused. The actual situation is that the temperature is well above 30 ° C.

  The present invention has been made in view of the above problems, and is a method for producing a high-quality and high-productivity diene rubber that reduces coloration with time and exhibits excellent activity by an industrially simple method. And it aims at providing the diene type rubber | gum obtained by it.

  As a result of intensive investigations to achieve the above object, the present inventors have so far required energy for cooling, and have not kept the ripening temperature at a low temperature. By controlling the temperature rise due to the reaction and the temperature rise due to the outside air temperature using a refrigerant, and controlling the temperature of the aging reaction between organoaluminum and water at a low temperature of −30 to 17 ° C. from the beginning to the end of aging. It is possible to promote the aging reaction of water and organoaluminum while suppressing the side reaction between impurities contained in the raw material and organoaluminum, thereby inhibiting the generation of color-causing substances that become side reaction products. The inventors have found that it is possible to provide a high-quality and high-productivity manufacturing method that reduces coloring with time and exhibits excellent activity, and has led to the present invention.

  That is, the present invention is a method for aging water and organoaluminum in a method for producing a diene rubber by maintaining a temperature range of −30 to 17 ° C. from the start of aging to the end of aging before polymerizing the diene monomer. The present invention relates to a method for producing a diene rubber that does not color with time.

  The present invention also relates to a diene rubber obtained by the above production method and not colored over time.

  As described above, according to the present invention, a method for producing a high-quality and high-productivity diene rubber that reduces coloration with time and exhibits excellent activity by an industrially simple method and a product obtained thereby. Diene rubber can be provided.

  The method for producing a diene rubber according to the present invention comprises (A) a diene monomer dissolved in (B) an organic solvent, (C) water dissolved therein, and then (D1) an organoaluminum cocatalyst is added. After aging the water and the organoaluminum (D2) while maintaining the temperature range of -30 to 17 ° C. from the start of ripening to the end of ripening, (E) a transition metal catalyst is added to polymerize, and after polymerization, (F) polymerization It is preferable to add a terminator and, optionally, (G) an antioxidant.

(A) Diene-based monomer Examples of the diene-based monomer include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, and the like. These may be used individually by 1 type, may mix 2 or more types, and also may be used by copolymerizing with other dienes, such as 1, 3- hexadiene. Of these, 1,3-butadiene is preferred.

  The raw material diene monomer used in the present invention may contain a polymerization inhibitor. As the polymerization inhibitor, a commonly used inhibitor can be used and is not particularly limited. For example, thiodiphenylamine, 4-tertiarybutylcatechol, 2,2-methylenebis-4-methyl-6-tersia Libutylphenol, hydroquinone, o-nitrophenol, m-nitrophenol, p-nitrophenol, 2,4-dinitrophenol, 2,4,6-trinitrophenol, p-methoxyphenol, p-benzoquinone, phenothiazine, anthraquinone 2,6-di-t-butylhydroxytoluene and the like.

  In addition, diethylhydroxylamine, dimethylhydroxylamine, methylethylhydroxylamine, dipropylhydroxylamine, dibutylhydroxylamine, dipentylhydroxylamine, phosphoric acid, phosphonic acid, phosphinic acid, diphosphonic acid, diphosphoric acid, tripolyphosphoric acid, and metaphosphoric acid A phosphoric acid compound, a dihydrogen phosphate alkyl ester compound, a hydrogen phosphate dialkyl ester compound, a phosphoric acid trialkyl ester compound, and the like selected from can also be used as a polymerization inhibitor.

  Among these, 4-tertiary butyl catechol (abbreviated as TBC) is particularly preferable.

(B) Organic solvent Examples of the organic solvent used in the present invention include aromatic hydrocarbons such as toluene, benzene and xylene, aliphatic hydrocarbons such as n-hexane, butane, heptane and pentane, cyclopentane and cyclohexane. Hydrocarbons such as alicyclic hydrocarbons, olefinic hydrocarbons such as 1-butene, cis-2-butene, trans-2-butene, mineral spirits, solvent naphtha, kerosene, and halogenated carbonization such as methylene chloride Examples thereof include hydrogen-based solvents. Further, 1,3-butadiene itself may be used as a polymerization solvent.

  The solvent is preferably a non-aromatic hydrocarbon, particularly cyclohexane.

(C) Water In the present invention, the timing of adding water is after (A) the diene monomer is dissolved in (B) an organic solvent, and then charged (D1) The molar ratio balance with the organoaluminum promoter is added. Is important.
(D1) The molar ratio (Al / H ₂ O) between the organoaluminum promoter and water is preferably 1 to 2.5, more preferably 1.05 to 2.4. If it is 1-2.3, it is especially preferable. (D1) When the molar ratio (Al / H ₂ O) between the organoaluminum cocatalyst and water is in the range of 1 to 2.5, it is possible not only to prevent color development (change in yellowish brown color). The molar ratio is also important in terms of productivity because it is possible to prevent a significant decrease in polymerization activity.

(D1) When the molar ratio (Al / H ₂ O) between the organoaluminum cocatalyst and water is less than 1 or greater than 2.5, the productivity of the rubber to be polymerized decreases and the color develops (changes in tan) This is not preferable because it tends to occur.

(D1) Organoaluminum promoter In the present invention, examples of the organoaluminum promoter that can be used include trialkylaluminum, dialkylaluminum chloride, dialkylaluminum bromide, alkylaluminum sesquichloride, alkylaluminum sesquibromide, and alkylaluminum dichloride. it can.

  One kind of these organoaluminum promoters may be used, or two or more kinds thereof may be used in combination. Of these, trialkylaluminum and dialkylaluminum chloride are particularly preferred, and when both are used in combination, the effects of the present application can be exhibited. Therefore, it is more preferable to use trialkylaluminum and dialkylaluminum chloride in combination.

  Specific compounds include trialkylaluminum such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum and tridecylaluminum; and dialkylaluminum chloride such as dimethylaluminum chloride and diethylaluminum chloride. it can.

  Further, organoaluminum halogen compounds such as sesquiethylaluminum chloride and ethylaluminum dichloride; hydrogenated organoaluminum compounds such as diethylaluminum hydride, diisobutylaluminum hydride and sesquiethylaluminum hydride are also included.

(D2) Aging temperature of water and organoaluminum The aging temperature of water and organoaluminum is −30 to 17 ° C., more preferably −15 to 15 ° C., and particularly preferably −10 to 10 ° C. When the aging temperature exceeds 17 ° C., the reaction between the organic aluminum and the impurities proceeds, and a causative substance for coloration with time is generated. In addition, the amount of alumoxane, which is an aging reaction product of organic aluminum and water, which is the original purpose of aging, is reduced and the activity is lowered. On the other hand, even if the temperature is lower than −30 ° C., side reactions between the organic aluminum and impurities can be suppressed and coloration with time can be reduced. However, it is industrially unpreferable to lower the temperature using a refrigerant.

  In general, the aging of water and organoaluminum is an exothermic reaction. For example, even when aging is started at 10 ° C., aging does not end at 10 ° C. In addition, the aging temperature is easily affected by a temperature increase due to the outside air temperature. However, normally, since energy for cooling is required, the aging temperature is not continuously controlled at a low temperature from the start to the end of aging.

On the other hand, in the present invention, it is important to keep the aging temperatures of water and organoaluminum at a low temperature from the start of aging to the end of aging using a refrigerant.
In the present invention, the aging start temperature is preferably -30 to 17 ° C, more preferably -20 to 15 ° C, and particularly preferably -15 to 10 ° C. Further, the aging end temperature is preferably -30 to 17 ° C, more preferably -20 to 15 ° C, and particularly preferably -15 to 10 ° C. The ripening start temperature and the ripening end temperature do not need to be the same, ripening is started in the temperature range of -30 to 17 ° C, ripening while maintaining the temperature range of -30 to 17 ° C, and -30 to 17 ° C. It is important that ripening is completed in the temperature range.

  In the present invention, the start of aging is (C) the time when (D1) organoaluminum is added to an organic solvent in which water is dissolved, and the end of aging is the time when (E) the transition metal catalyst is added. Point to.

In the method for producing a diene rubber of the present invention, (A) a diene monomer is dissolved in (B) an organic solvent, (C) water is dissolved therein, and then (D1) an organoaluminum promoter is added to water. The molar ratio of (Al / H ₂ O) is in the range of 1 to 2.5, and (D2) is maintained at a temperature range of −30 to 17 ° C. from the start of ripening to the end of ripening, and (D3 ) It is more effective to produce a diene rubber that does not color with time when (E) a transition metal catalyst is added and polymerized after aging for 1 to 60 minutes.

That is, (D1) By using together the conditions that limit the range of the molar ratio (Al / H ₂ O) between the organoaluminum cocatalyst and water, an effect of preventing coloration with time can be further created.

(D3) Aging time of water and organoaluminum The aging time of water and (D3) organoaluminum is particularly preferably 1 to 60 minutes, more preferably 3 to 50 minutes, and most preferably 5 to 45 minutes. If the aging time is shorter than 1 minute, the alumoxane that is an aging reaction product cannot be sufficiently formed, and the reaction between the unreacted organoaluminum and impurities proceeds. If the aging time is longer than 60 minutes, the unstable alumoxane Can not continue to be maintained, can not work in the polymerization reaction, the polymer produced per catalyst is reduced, tends to cause coloration.

(E) Transition metal catalyst In the present invention, examples of the transition metal catalyst that can be used include a cobalt-based catalyst.

  As the cobalt-based catalyst, a cobalt salt or complex is preferably used. Cobalt salts such as cobalt chloride, cobalt bromide, cobalt nitrate, cobalt octylate (ethylhexanoate), cobalt naphthenate, cobalt acetate and cobalt malonate; cobalt bisacetylacetonate and trisacetylacetonate And organic base complexes such as acetoacetic acid ethyl ester cobalt, cobalt salt pyridine complex and picoline complex, or ethyl alcohol complex.

  Among these, cobalt octylate is particularly preferable.

The diene rubber of the present invention can be produced with a catalyst other than cobalt.
Examples of catalysts other than cobalt-based catalysts include nickel-based and neodymium-based catalysts.

  Examples of the nickel-based catalyst include a catalyst system composed of a nickel compound-organoaluminum compound.

  Examples of the nickel compound include organic acid salts such as nickel naphthenate, nickel formate, nickel octylate, nickel stearate, nickel citrate, nickel benzoate and nickel toluate; organic complex compounds such as nickel acetylacetonate; Examples include nickel sulfonate; nickel oxyborate.

  Among these, nickel octylate is preferable.

  Furthermore, as the form of the diene polymer corresponding to the type of metal catalyst, lithium catalyst polymerization-polybutadiene (Li-BR), cobalt catalyst polymerization-polybutadiene (Co-BR), neodymium catalyst polymerization-polybutadiene (Nd-BR), nickel Catalytic polymerization-polybutadiene (Ni-BR), titanium catalytic polymerization-polybutadiene (Ti-BR), styrene-butadiene block copolymer (SB, SBS, SEBS), random styrene-butadiene-copolymer (L-SBR), butadiene-isoprene -Copolymer (BI), styrene-butadiene-isoprene-terpolymer (SIB) and the like.

  Of these, cobalt-catalyzed polymerization-polybutadiene (Co-BR) is particularly suitable for the method of the present invention.

  In the present invention, a known molecular weight regulator, for example, non-conjugated dienes such as cyclooctadiene and allene, or α-olefins such as ethylene, propylene and butene-1 may be added during polymerization. it can.

  In the present invention, the polymerization temperature is preferably in the range of -30 to 100 ° C, particularly preferably in the range of 30 to 80 ° C. The polymerization time is preferably in the range of 5 minutes to 12 hours, particularly preferably 10 minutes to 6 hours. The polymerization pressure is performed under normal pressure or a pressure up to about 10 atmospheres (gauge pressure).

(F) Polymerization terminator The polymerization of the diene rubber is interrupted by the addition of water, alcohol, organic acid or inorganic acid and / or phenol in the usual manner. It is advantageous in terms of cost to interrupt the polymerization according to the invention with water.

Among these, dispersibility is good, and preferable polymerization terminators include water and lower alcohols. The amount of water used is 1.38 × 10 ^{−8 to} 9.9 vol in terms of the total raw material mixture solution. %, Preferably 2.76 × 10 ^{−8 to 5} vol%, more preferably 4.14 × 10 ^{−8 to 3} vol%. The total raw material mixed solution is the total amount of the diene monomer and solvent that are raw materials charged into the reactor.

  The lower alcohol preferably has 5 or less carbon atoms, and specifically includes methanol, ethanol, propanol, isopropanol, butanol, ter-butyl alcohol, pentanol and isomers thereof. These may be used alone or in combination.

  In the present invention, (G) an antioxidant may be added as necessary after (F) the polymerization terminator, but (G) the antioxidant and (F) the polymerization terminator are added. The order may be reversed.

(G) Antioxidant Antioxidants include 4,6-bis (octylmethyl) -o-cresol, tertiary butylhydroquinone, dinitrochlorobenzene, hydroquinone and water, dimethyldithiocarbamate, sodium polysulfide, polyethylene polyamine And amine compounds such as diethylhydroxylamine and hydroxylamine, quinone compounds such as benzoquinone, sodium nitrate, sodium dithiocarbamate, phenothiazine, and 2,6-t-butyl-4-methylphenol.

  Among these, 4,6-bis (octylmethyl) -o-cresol is preferable.

The addition amount of the antioxidant is preferably from 8.256 × 10 ^{−6 to} 3.754 × 10 ⁻⁴ mol with respect to 1 mol of the diene monomer. Since the antioxidant also reacts with organoaluminum in the same manner as the impurities contained in the raw material, if the amount of the antioxidant added exceeds 3.754 × 10 ⁻⁴ , the coloration with time deteriorates, and conversely, 8. If the amount is less than 256 × 10 ⁻⁶ , the deterioration proceeds and the coloring is deteriorated.

  The diene rubber produced according to the present invention is characterized by low coloration with time. Specifically, the value of ΔYI (YI (2 months) −YI (1 week)) is preferably 15 or less.

  The diene rubber that is not colored over time produced according to the present invention is used to produce all types of vulcanizates. It can also be used for the production and for the impact modification of polymers based on vinyl aromatic compounds such as polystyrene and bulk-processed ABS-polymers.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, these do not limit the objective of this invention. First, the analysis methods used in the examples are shown below.

(Coloring measurement)
In addition to visual observation, the coloration was measured quantitatively with a yellow index (YI value) using NDJ-300A manufactured by Nippon Denshoku Industries Co., Ltd.

(Calculation of conversion)
In the case of 1 L of the raw material mixed solution (cyclohexane 20 wt%, butadiene 40 wt%, butene 40 wt%), the specific gravity is 0.65, so the weight is 650 g. Since the butadiene monomer is 40 wt% in the weight of 650 g, it can be calculated that 650 × 0.4 = 260 g.
For example, when 120 g of polybutadiene can be obtained after the polymerization reaction, 120 g / 260 g≈0.46, and the conversion is 46%.

(Mooney viscosity (ML _{1 + 4} , 100 ° C))
It measured based on JISK6300.

(Toluene solution viscosity (Tcp))
After dissolving 2.28 g of the polymer in 50 ml of toluene, a standard solution for calibrating viscometer (JIS Z 8809) was used as a standard solution, and Canon Fenske viscometer No. 400 was used and measured at 25 ° C.

Example 1
The inside of the polymerization autoclave having an internal volume of 1.5 L was purged with nitrogen, and 1 L of a raw material mixed solution (cyclohexane 20 wt%, butadiene 40 wt%, butene 40 wt%) was charged and stirred. Next, 3.64 mmol of water was added and stirring was continued at room temperature for 30 minutes. Then, after lowering to 10 ° C (ripening start temperature), 3 mmol of diethylaluminum chloride (DEAC) and 1 mmol of triethylaluminum (TEA) were added, and the temperature was kept constant at 10 ° C with ice water and hot water for 15 minutes. And matured. The molar ratio (Al / H ₂ O) between the total organoaluminum catalyst (4 mmol / l) and water is 1.10. Thereafter, 11 mmol of 1,5-cyclooctadiene (COD) is added as a molecular weight regulator, the temperature of the solution is 50 ° C., 7.8 μmol of cobalt octylate (Co (Oct) ₂ ) is added, and polymerization is started. Polymerization was carried out for 30 minutes. After the reaction, 0.2355 mmol of 4,6-bis (octylmethyl) -o-cresol (cas-number 110553-27-0) was added as an antioxidant in an ethanol solution and stirred for 1 minute.
Thereafter, the solvent was vacuum dried at 100 ° C. for 1 hour from the recovered polybutadiene solution to obtain polybutadiene. The results are shown in Table 1. The color measurement was carried out after 1 week, 2 weeks, 1 month and 2 months after production.

(Example 2)
After dissolving in water, the temperature is lowered to 10 ° C., 3 mmol of diethylaluminum chloride (DEAC) and 1 mmol of triethylaluminum (TEA) are added, and the temperature is kept constant at 15 ° C. with ice water and hot water, and the mixture is aged for 15 minutes. The procedure was the same as in Example 1 except that. The results are shown in Table 1.

(Example 3)
After dissolution in water, the temperature is lowered to 10 ° C., then 3 mmol of diethylaluminum chloride (DEAC) and 1 mmol of triethylaluminum (TEA) are added. The temperature is kept constant at 17 ° C. with ice water and hot water, and the mixture is aged for 15 minutes. The procedure was the same as in Example 1 except that. The results are shown in Table 1.

(Comparative Example 1)
After dissolving in water, the temperature was lowered to 20 ° C., 3 mmol of diethylaluminum chloride (DEAC) and 1 mmol of triethylaluminum (TEA) were added, and the temperature was kept constant at 20 ° C. with ice water and hot water, and the mixture was aged for 15 minutes. Was carried out in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
After dissolving in water, the temperature is lowered to 10 ° C., 3 mmol of diethylaluminum chloride (DEAC) and 1 mmol of triethylaluminum (TEA) are added, and the temperature is kept constant at 20 ° C. with ice water and hot water, and the mixture is aged for 15 minutes. The procedure was the same as in Example 1 except that. The results are shown in Table 1.

Example 4
After dissolving in water, the temperature was lowered to 5 ° C., 3 mmol of diethylaluminum chloride (DEAC) and 1 mmol of triethylaluminum (TEA) were added, the temperature was kept constant at 5 ° C. with ice water and hot water, and the mixture was aged by stirring for 15 minutes. Was carried out in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
After dissolving in water, the temperature was lowered to 5 ° C., 3 mmol of diethylaluminum chloride (DEAC) and 1 mmol of triethylaluminum (TEA) were added, and the temperature was kept constant at 15 ° C. with ice water and hot water, and the mixture was aged for 15 minutes. Was carried out in the same manner as in Example 1. The results are shown in Table 1.

(Example 6)
After dissolving in water, the temperature was lowered to 5 ° C., 3 mmol of diethylaluminum chloride (DEAC) and 1 mmol of triethylaluminum (TEA) were added, and the temperature was kept constant at 17 ° C. with ice water and hot water, and the mixture was aged by stirring for 15 minutes. Was carried out in the same manner as in Example 1. The results are shown in Table 1.

(Example 7)
After dissolving in water, the temperature was lowered to 5 ° C., 3 mmol of diethylaluminum chloride (DEAC) and 1 mmol of triethylaluminum (TEA) were added, and the temperature was controlled at −20 ° C. with cooled methanol water and hot water, and the mixture was stirred for 15 minutes. The same procedure as in Example 1 was performed except that the mixture was aged. The results are shown in Table 1.

(Comparative Example 3)
After dissolving in water, the temperature was lowered to 5 ° C., 3 mmol of diethylaluminum chloride (DEAC) and 1 mmol of triethylaluminum (TEA) were added, and the temperature was kept constant at 20 ° C. with ice water and hot water, and the mixture was aged by stirring for 15 minutes. Was carried out in the same manner as in Example 1. The results are shown in Table 1.

(Example 8)
A half amount of 500 mL of a raw material mixed solution (cyclohexane 20 wt%, butadiene 40 wt%, butene 40 wt%) was charged and stirred. Next, 3.64 mmol of water was added and stirring was continued at room temperature for 30 minutes. Thereafter, the temperature is lowered to 10 ° C. (ripening start temperature), 3 mmol of diethylaluminum chloride (DEAC) and 1 mmol of triethylaluminum (TEA) are added, and the temperature is kept constant at 15 ° C. with ice water and hot water and stirred for 15 minutes. And matured. Thereafter, the remaining 500 ml of the raw material mixed solution was fed. Other than that was carried out in the same manner as in Example 1. The results are shown in Table 1.

  From the results in Table 1, it can be seen that Examples 1 to 3 have lower coloration with time (change in YI per elapsed day) and higher conversion than Comparative Examples 1 and 2.

  In addition, it can be seen that Examples 4 to 7 have lower coloration with time (change in YI per elapsed day) and higher conversion than Comparative Example 3.

  Furthermore, as in Example 8, even when the ripening concentration is 200%, the aging concentration (change amount of YI per elapsed days) is low, so the aging concentration may be 100% or 200%. It turned out to be possible to go.

Example 9
The inside of the polymerization autoclave having an internal volume of 1.5 L was purged with nitrogen, and 1 L of a raw material mixed solution (cyclohexane 30 wt%, butadiene 35 wt%, butene 35 wt%) was charged and stirred. Next, 0.91 mmol of water was added and stirring was continued at room temperature for 30 minutes. Thereafter, the temperature was lowered to 10 ° C. (ripening start temperature), 2 mmol of diethylaluminum chloride (DEAC) was added, and the temperature was kept constant at 10 ° C. with ice water and hot water, and the mixture was aged for 15 minutes. The molar ratio (Al / H ₂ O) between the total organoaluminum catalyst (2 mmol / l) and water is 2.2. Thereafter, 10 mmol of 1,5-cyclooctadiene (COD) is added as a molecular weight regulator, the temperature of the solution is 50 ° C., 17 μmol of cobalt octylate (Co (Oct) ₂ ) is added, polymerization is started, and 30 minutes Polymerization was performed. After the reaction, 0.2355 mmol of 4,6-bis (octylmethyl) -o-cresol (cas-number 110553-27-0) was added as an antioxidant in an ethanol solution and stirred for 1 minute.
Thereafter, the solvent was vacuum dried at 100 ° C. for 1 hour from the recovered polybutadiene solution to obtain polybutadiene. The results are shown in Table 2.

(Example 10)
After dissolving in water, the temperature was lowered to 10 ° C., 2 mmol of diethylaluminum chloride (DEAC) was added, and the temperature was kept constant at 15 ° C. with ice water and hot water, and the mixture was aged by stirring for 15 minutes. The same was done. The results are shown in Table 2.

(Example 11)
After dissolving in water, the temperature was lowered to 10 ° C., 2 mmol of diethylaluminum chloride (DEAC) was added, and the temperature was kept constant at 17 ° C. with ice water and hot water, and the mixture was aged by stirring for 15 minutes. The same was done. The results are shown in Table 2.

(Comparative Example 4)
After dissolving in water, the temperature was lowered to 10 ° C., 2 mmol of diethylaluminum chloride (DEAC) was added, and the temperature was kept constant at 20 ° C. with ice water and hot water, and the mixture was aged by stirring for 15 minutes. The same was done. The results are shown in Table 2.

  From the results in Table 2, it can be seen that Examples 9 to 11 have lower coloration with time (change in YI per elapsed day) and higher conversion than Comparative Example 4.

  From the above, Table 1 shows a comparison when Al / H is 1.1 in a combined system of trialkylaluminum and dialkylaluminum chloride, and Table 2 shows a comparison when Al / H is 2.2 in a dialkylaluminum chloride alone system. . Under either condition, by maintaining the aging temperature at 17 ° C. or less from the beginning to the end of aging, a remarkable improvement effect was obtained in ΔYI and the conversion rate.

In addition, the improvement value of (DELTA) YI when set to 17 degrees C or less is larger in the combined use system of a trialkylaluminum and a dialkylaluminum chloride. In the case of the combined system, ΔYI = 11.7 of Example 1 and ΔII = 11.7 of Comparative Example 2 were improved to 6.7. In the case of the single system, ΔYI = 8.8 in Example 9 and ΔII = 18.8 in Comparative Example 4 are 6.4, and the improvement value is 6.4.
As described above, as the improved value of ΔYI, the combined system of trialkylaluminum and dialkylaluminum chloride is more effective, and the combined system of trialkylaluminum and dialkylaluminum chloride is the absolute value of coloring degree. Therefore, the improvement merit in this application is great.

Claims (1)

In the production method of diene rubber,
Before polymerizing diene monomer, keeping the temperature range of the completion of the aging to -30～17 ° C. from ripening starts, have a water and diethyl aluminum chloride and a step of aging 5-60 minutes triethylaluminum,
A method for producing a diene rubber, wherein the molar ratio (Al / H ₂ O) of diethylaluminum chloride and triethylaluminum to water is 1 to 2.5 .