JP2000212213A - Method for producing modified polybutadiene, modified polybutadiene, and rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a modified polybutadiene which becomes a rubber component having a low rolling resistance and a high wet skid resistance when used as a rubber material for automobile tires. SOLUTION: In a preparation process of a modified polybutadiene, 1,3-butadiene is polymerized in the presence of a cobalt catalyst composition comprising a cobalt compound, a halogen-containing organic aluminum compound and water or a nickel catalyst composition comprising a nickel compound, an organic aluminum compound and a fluorine compound to obtain a polybutadiene, which is subsequently modified with an aromatic compound having at least two amino groups and one carboxyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a modified polybutadiene which is particularly useful as a rubber material for a tire tread, a method for producing the same, and a rubber composition which can be effectively used as a rubber material for a tire tread.

[0002]

2. Description of the Related Art Conjugated diene copolymer rubbers such as polybutadiene and butadiene-styrene copolymer rubber have been used as rubbers for treads of automobile tires. Demand for running stability in automobiles, as rubber for automobile tire treads,
There is a demand for a rubber material having a small rolling resistance and a large road grip on snow and ice.

As a means for solving this problem, many methods have been proposed for introducing a specific atomic group into a polymer by, for example, reacting an alkali metal-containing diene polymer with a specific compound. .

[0004] JP-A-58-162604 and JP-A-59-117514 describe a method of modifying a rubber component by reacting it with benzophenone. JP-A-6-57769 and JP-B-6-78450 describe a method in which a rubber component is modified by reacting it with a nitroamino compound, a nitro compound or a nitroalkyl compound.

[0005] However, at present, it has not been possible to obtain a sufficiently satisfactory rubber material by these methods. Further, in the rubber material obtained by these methods, the cis-1,4 content in the microstructure of the polymer is not obtained. And the abrasion resistance is inferior to the high cis polymer. On the other hand, as a catalyst that provides a high cis polymer, a Co catalyst, a Ni catalyst, a Ti catalyst, an Nd catalyst, and the like are known.
Since the catalyst and the Ti catalyst do not have a living property, a method for producing a modified polymer by adding a modifying agent to a polymerization system has not been proposed.

A method for producing a modified polymer by adding a solvent to a high cis polymer, dissolving the solution, and bringing a catalyst and a modifier into contact with the solution is already known. For example, JP
JP-A-8-142901 discloses that a rubber is dissolved in a solvent, and a rubber having an unsaturated bond is reacted with an organic compound having a carboxyl group and an aldehyde group in the presence of an acid catalyst.
Methods for modifying rubber have been proposed. See also
JP-A-8-162602 proposes a method in which a rubber is dissolved in a solvent, and a rubber having an unsaturated bond is reacted with an organic compound having a carboxyl group and a salt of an aromatic sulfone halamide.

Japanese Patent Application Laid-Open No. Sho 61-225202 describes a method in which a rubber having an unsaturated bond is dissolved in a solvent, and benzylidenebutylamine or an organic acid halide is reacted in the presence of a Lewis acid to modify the rubber. Have been. All of these methods require a step of forming a rubber solution in which rubber is dissolved with a solvent, and thus require a large amount of solvent. Therefore, it has been desired to develop a method for obtaining a modified rubber having a high cis content by saving such a complicated operation by directly adding a modifying agent to the polymerization system.

As this method, there has been proposed a method in which a modifier is directly added to a conjugated diene polymer having pseudo-living properties produced using an Nd catalyst. For example, Japanese Unexamined Patent Publication (Kokai) No. 63-178102 discloses that a conjugated diene is polymerized by using a lanthanum series rare earth metal catalyst, and a polymer immediately after the polymerization is reacted with a specific organic metal halide to form a modified conjugated diene-based polymer. A method for producing a coalescence is described. JP-A-63-297403 discloses that a conjugated diene is polymerized by using a lanthanum series rare earth metal catalyst, and a polymer immediately after the polymerization is reacted with a specific heterocumulene compound or a hetero three-membered ring compound. A method for producing a modified conjugated diene polymer has been proposed. JP-A-63-305101 discloses a modified conjugated diene polymer in the same manner as described above, except that a specific halogen compound such as 2,4,6-trichloro-1,3,5-triazine is added as a modifier. Are described.

[0009]

However, the polymerization reaction of a conjugated diene using a lanthanum series rare earth metal catalyst has a disadvantage that the polymerization reaction rate per unit catalyst amount is lower than that of a Co catalyst or a Ni catalyst. . On the other hand, performing the same modification reaction with a Co catalyst or a Ni catalyst as in the case of a lanthanum series rare earth metal catalyst is difficult with a Co catalyst or an N catalyst.
Since the i catalyst has no living property or pseudo-living property,
It was considered impossible.

[0010]

Means for Solving the Problems Accordingly, the present inventors have:
Considering the possibility of introducing a modifying agent into a rubber having an unsaturated bond by producing a high-cis structure polybutadiene rubber with high activity and adding a modifying agent immediately after polymerization, we have earnestly based on this idea. As a result of the research, a cobalt-based catalyst composition (a composition containing a cobalt compound, a halogen-containing organoaluminum compound and water as active ingredients) or a nickel-based catalyst composition (containing a nickel compound, an organoaluminum compound and a fluorine compound as active ingredients) Composition)), an aromatic compound having at least two amino groups and one carboxyl group is added as a modifier to the polybutadiene immediately after polymerization obtained by polymerizing 1,3-butadiene. To produce modified polybutadiene with excellent properties. Thus, the present invention has been attained.

Accordingly, the present invention provides a cobalt catalyst composition comprising a cobalt compound, a halogen-containing organoaluminum compound and water, or a nickel catalyst comprising a nickel compound, an organoaluminum compound and a fluorine compound. After polymerization in the presence of the catalyst composition to polybutadiene, this polybutadiene,
A method for producing a modified polybutadiene, comprising modifying with an aromatic compound having at least two amino groups and one carboxyl group.

The present invention also relates to a modified polybutadiene obtained by the above production method of the present invention, wherein at least 80% of its repeating units have a cis-1,4 structure and a Mooney viscosity (ML _{1 + 4} , 100 ° C.) is in the range of 20 to 80, and the weight average molecular weight by gel permeation method is 2
There is also a modified polybutadiene characterized in that the modified polybutadiene is in the range of from 0.00000 to 1,000,000 and the nitrogen content is in the range of from 10 to 5000 ppm.

[0013] The present invention also provides a rubber composition comprising the above-mentioned modified polybutadiene in a rubber component at least 10% by weight.

The catalyst composition used in the method for producing a modified polybutadiene according to the present invention is preferably a cobalt-based catalyst composition.
All amounts per mol of 1,3-butadiene are 1 × 10 ⁻⁷ to 1 × 10 ⁻³ mol for the cobalt compound and 1 × 10 ⁻³ mol for the halogen-containing organoaluminum compound.
× 10 ^-5 to 1 × 10 ^-1 mol, and 1 for water
Desirably, it is from × 10 ^-5 to 1 × 10 ^-1 mol.

In the method for producing a modified polybutadiene of the present invention, a nickel-based catalyst composition may be used instead of a cobalt-based catalyst composition as a catalyst composition. For 1 mol of 1,3-butadiene, 1 × 10
^-7 to 1 × 10 ^-3 mol, 1 × 10 ^-5 to 1 × 10 ^-1 mol for the organoaluminum compound (organoaluminum compound containing no halogen atom) component, and 1 × 10 ^-1 mol for the fluorine compound. It is preferably from ^-4 to 1 mol.

In the present invention, the cobalt compound is preferably a cobalt salt of a carboxylic acid having 1 to 18 carbon atoms, and the halogen-containing organoaluminum compound is preferably a dialkylaluminum halide having 2 to 10 carbon atoms in total. , Alkyl aluminum dihalide,
Alternatively, it is preferably an alkyl aluminum sesquihalide. As the diamine compound, the number of carbon atoms is 2
It is preferable to use from 6 to 6 diaminoalkanes.

[0017]

Next, the method for producing the modified polybutadiene of the present invention, the modified polybutadiene obtained by the production method, and the use of the modified polybutadiene as a rubber material for a tire tread will be described in more detail.

When a cobalt-based catalyst composition is used, a cobalt salt or complex is preferably used. Particularly preferred are cobalt halides such as cobalt chloride and cobalt bromide, cobalt salts of inorganic acids such as cobalt nitrate, cobalt octylate, cobalt acetate, and cobalt carboxylate having 1 to 18 carbon atoms such as cobalt octoate; Cobalt complexes such as cobalt naphthenate, cobalt malonate, cobalt bisacetylacetonate, cobalt trisacetylacetonate, and ethyl acetoacetate; triarylphosphine complexes, cobalt halide halides, trialkylphosphine complexes, pyridine complexes and picoline complexes Various complexes such as an organic base complex and an ethyl alcohol complex are exemplified.

When the nickel-based catalyst composition is used, a nickel salt or complex is preferably used. Particularly preferred are nickel halides such as nickel chloride and nickel bromide, nickel salts of inorganic acids such as nickel nitrate, nickel octylate, nickel acetate, nickel carboxylate having 1 to 18 carbon atoms such as nickel octoate, Nickel complexes such as nickel naphthenate, nickel malonate, nickel bisacetylacetonate, trisacetylacetonate, ethyl acetoacetate, nickel halide triarylphosphine complex, trialkylphosphine complex, pyridine complex and picoline complex Various complexes such as an organic base complex and an ethyl alcohol complex are exemplified.

When a cobalt-based catalyst composition is used, the halogen-containing organoaluminum compound may be R _3-n Al
X _n (where R is a hydrocarbon group having 1 to 10 carbon atoms, X
Represents a halogen, and n is an integer of 1 to 2. )) Can be mentioned. Examples thereof include dialkyl aluminum chloride, dialkyl aluminum halide such as dialkyl aluminum bromide, alkyl aluminum sesquichloride, alkyl aluminum sesquihalide such as alkyl aluminum sesquibromide, alkyl aluminum dichloride, and alkyl aluminum dibromide such as alkyl aluminum dibromide. No. Specific compounds include diethylaluminum monochloride, diethylaluminum monobromide, dibutylaluminum monochloride, ethylaluminum sesquichloride, ethylaluminum dichloride, dicyclohexylaluminum monochloride, diphenylaluminum monochloride and the like.

As the organoaluminum compound when a nickel-based catalyst composition is used, a trialkylaluminum represented by AlR ₃ (R represents a hydrocarbon group having 1 to 10 carbon atoms) can also be preferably used. Examples of such trialkylaluminums include trimethylaluminum, triethylaluminum, tri-aluminum.
n-propyl aluminum, triisopropyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum, tripentyl aluminum, trihexyl aluminum, tricyclohexyl aluminum, trioctyl aluminum, triphenyl aluminum,
Tri-p-tolyl aluminum and tribenzyl aluminum can be mentioned. The three alkyl groups in the trialkylaluminum may be the same or different from each other.

When the nickel-based catalyst composition is used, the fluorine compound may be a boron trifluoride ether, an alcohol, or a complex of a mixture thereof, or a hydrogen fluoride ether, an alcohol, or a mixture of these complexes. Can be Particularly preferred fluorine compounds include
Boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, hydrogen fluoride diethyl etherate, and hydrogen fluoride dibutyl etherate can be mentioned.

As the catalyst composition used in the method for producing a polybutadiene to be modified according to the present invention, a cobalt-based catalyst composition is preferable. The amount of the cobalt compound used is preferably in the range of 1 × 10 ⁻⁷ to 1 × 10 ⁻³ mol per 1 mol of 1,3-butadiene as the raw material monomer. The amount of the halogen-containing organoaluminum compound is 1 × 10
In the range of ^-5 to 1 × 10 ^-1 mol, and it is preferable that the amount of water used is in the range of 1 × 10 ^-5 ~1 × 10 ^-1 mol per 1 mol of the cobalt compound.

The order of adding the catalyst components to the reaction system is not limited. Each catalyst component can be added simultaneously or in any order.

The polymerization method is not particularly limited, and polymerization methods generally used for 1,3-butadiene, such as bulk polymerization and solution polymerization, can be used. Examples of the solvent in the solution polymerization include aromatic hydrocarbons such as toluene, benzene, and xylene; aliphatic hydrocarbons such as n-hexane, butane, heptane, and pentane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; Olefinic hydrocarbons such as -butene, cis-2-butene, trans-2-butene, mineral spirits, solvent naphtha, kerosene and the like; and hydrocarbon solvents such as methylene chloride and the like can be used. it can. Further, 1,3-butadiene itself may be used as a polymerization solvent. Among them, benzene, cyclohexane, a mixture of cis-2-butene and trans-2-butene, and the like are suitably used as a solvent for solution polymerization.

In the process for producing polybutadiene according to the present invention, a known molecular weight regulator, for example, a non-conjugated diene such as cyclooctadiene or arene, or ethylene, propylene or butene-1 or the like may be used during the polymerization reaction. Α-
Olefins can be used.

[0027] 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 10 minutes to 12 hours, particularly preferably 30 minutes to 6 hours. The polymerization is carried out under normal pressure or under pressure up to about 10 atmospheres (gauge pressure). In the production of the modified polybutadiene of the present invention, an aromatic compound having at least two amino groups and one carboxyl group is immediately used as a modifying agent immediately after polymerization of 1,3-butadiene at a predetermined temperature for a predetermined time. A denaturation reaction is performed by the addition.

In the method for producing a modified polybutadiene of the present invention, an aromatic compound having at least two amino groups and one carboxyl group is used as a modifying agent. Examples of specific compounds include 2,3-diaminobenzoic acid,
Examples include 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,4-diaminobenzoic acid, and 3,5-diaminobenzoic acid. Particularly preferred is
3,4-diaminobenzoic acid and 3,5-diaminobenzoic acid.

These modifiers may be used alone,
Alternatively, a plurality of combinations may be used.

The amount of the modifier used is 0.01 to 100 g per 100 g of the produced polybutadiene (polybutadiene rubber).
It is 150 mmol, preferably 1 to 100 mmol, more preferably 3 to 50 mmol. If the amount of the modifying agent is small, the modifying effect is less likely to appear. On the other hand, if the amount is too large, the unreacted modifier tends to remain in the polybutadiene, and it takes time to remove it, which is not preferable.
In addition, it is preferable that the Mooney viscosity of the modified product is increased by one or more as compared with that before the modification.

The denaturation temperature is preferably in the range of 0 to 100 ° C, more preferably in the range of room temperature to 70 ° C. If the temperature is too low, the progress of the modification reaction is slow, and if the temperature is too high, the polymer gels, which is not preferable. Usually, it is preferable to carry out the modification reaction at the same temperature as the polymerization temperature. The denaturation time is not particularly limited, but is usually preferably in the range of 0.5 to 6 hours. If the denaturation time is too short, the reaction does not proceed sufficiently, and if the denaturation time is too long, the polymer may gel, which is not preferable.

Also, immediately after the polymerization of 1,3-butadiene,
Prior to the addition of the modifying agent, an aluminum halide or an alkyl halide (the alkyl group has 1 to 6 carbon atoms) may be added as a catalyst in order to accelerate the progress of the modifying reaction. Examples of aluminum halides include aluminum chloride, aluminum bromide, and aluminum iodide. Examples of the alkyl halide include ethyl bromide, ethyl iodide, butyl chloride, butyl bromide, and butyl iodide. The amount of this catalyst to be used is 0.01 to 50 mmol, preferably 0.05 to 30 mmol, more preferably 0.1 to 20 mmol, per 100 g of polybutadiene.

In the modified polybutadiene (modified polybutadiene rubber) of the present invention obtained by the above-mentioned production method, 80% or more of its repeating units have a cis-1,4 structure,
Mooney viscosity (ML _{1 + 4} , 100 ° C.) is in the range of 20 to 80, weight average molecular weight by gel permeation is in the range of 200,000 to 1,000,000, and nitrogen content is 10 to 5000 ppm. Is desirably within the range.

The modified polybutadiene obtained according to the present invention is blended alone or blended with another synthetic rubber or natural rubber, and if necessary, oil-extended with a process oil, and then a filler such as carbon black, vulcanization, etc. Vulcanization by adding an agent, a vulcanization accelerator and other usual compounding agents, and is used for rubber applications requiring mechanical properties and abrasion resistance of tires, hoses, belts and other various industrial products. It can also be used as a plastic modifier.

When the modified polybutadiene obtained by the present invention is used as a rubber material for an automobile tire tread, at least 10 parts of the modified polybutadiene of the present invention are contained in the rubber component of a rubber composition comprising a rubber component and a compounding agent. It is preferable to mix them so as to contain them by weight.

[0036]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but these do not limit the present invention. In addition, Mooney viscosity (ML _{1 + 4} , 100 ° C.), cis-1,4-content, nitrogen content, weight average molecular weight, molecular weight distribution and gel content of the rubbery polymers obtained in the following Examples and Comparative Examples. The rate was measured by the following method.

(1) Mooney viscosity (ML _{1 + 4} , 100
° C): 1 according to JIS-K6300 using a Mooney viscometer (SMV-200) manufactured by Shimadzu Corporation.
After preheating at 00 ° C for 1 minute, it was measured for 4 minutes and indicated as the Mooney viscosity of the rubber (ML _{1 + 4} , 100 ° C). (2) cis-1,4-content (%): By measuring the microstructure of the polymer using a 0.4% by weight carbon disulfide solution by infrared absorption spectroscopy,
The 1,4-content was calculated. (3) Nitrogen content (ppm): Determined by the Kjeldahl method according to JIS-K0102.

(4) Weight average molecular weight and molecular weight distribution: Gel permeation (permeation) chromatography (GPC, manufactured by Tosoh Corporation) was performed at a temperature of 40 ° C. using polystyrene as a standard substance and tetrahydrofuran as a solvent, and the obtained molecular weight. The weight average molecular weight (Mw) and number average molecular weight (Mw) were calculated using a calibration curve obtained from the distribution curve.
n) was determined, and the weight average average molecular weight and the molecular weight distribution (Mw / Mn) were displayed. (5) Method of measuring gel fraction: about 0.5% of unvulcanized rubber sample
g, cut into small pieces and accurately weigh (R
g). The weight of a separately prepared 100-mesh stainless steel basket is precisely weighed (Kg), the weighed sample is entirely transferred to the basket, and the weight is measured (Rg + Kg). This is toluene 1
Immersed in a bottle with a cap
Leave for 4 hours. Next, the basket was lifted and the temperature was set to 2 at 23 ° C.
After drying for 4 hours, further adjust to a constant weight at 70 ° C.
After drying under reduced pressure for 4 hours, the toluene-insoluble matter was accurately weighed together with the basket (Gg + Kg), and the gel fraction was determined by the following equation.

Gel fraction (%) = 100 × [G− (R ×
(Filler parts ÷ rubber composition total parts)] ÷ [(R ×
(Parts by weight of rubber: total parts by weight of rubber composition)] However, parts by weight of filler: parts by weight of carbon black in Table 1 Total parts by weight of rubber composition: total parts by weight of all components in Table 1 Parts by weight of rubber: The rubber components (NR + BR or modified B
R) total weight parts

Further, 300% elastic modulus, rolling resistance index,
The tensile strength and wet skid resistance index were measured by the following methods. (1) 300% modulus (M _300): JIS-K6301
And the modulus at 300%. (2) Rolling resistance index: Using a viscoelastic spectrometer VES manufactured by Iwamoto Seisakusho, tan δ was measured at a temperature of 70 ° C., an initial distortion of 10%, and a dynamic strain of 2%, and the rolling resistance was calculated by the following equation. An index was determined. A larger index value indicates a lower rolling resistance, and the rolling resistance may be 100 or more.

Rolling resistance index = 100 × [(value of comparative example (unmodified product)) / (value of example (modified product)]]

(3) Tensile strength: Measured according to JIS-K-6301. (4) Wet skid resistance index: ASTM-E303- using a portable skid resistance meter manufactured by Stanley.
83. Indices of grip characteristics (driving performance, braking performance and steering performance) on a wet road surface indicate that the larger the value, the better.

[Example 1]
In a 5-liter stainless steel autoclave,
Benzene -C ₄ fraction mixed l of solution (benzene 26.9% by weight containing 1,3-butadiene 27.9 wt%, the C ₄ fraction composed mainly of cis-2-butene 4
Then, 2 mmol of water and 2.9 mmol of diethylaluminum monochloride were added thereto, followed by stirring, and 4.24 mmol of cyclooctadiene was added. The temperature of the autoclave was raised, and after the internal temperature reached 58.5 ° C., cobalt octoate 0.008
After adding 7 mmol, a polymerization reaction was carried out at 60 ° C. for 30 minutes. Then, immediately at 60 ° C., 1.0 mmol of 3,4-diaminobenzoic acid was added as a denaturant,
The denaturation reaction was performed for 0 minutes.

After completion of the reaction, unreacted gas is discharged out of the system,
500 ml of toluene was added to make a modified polybutadiene solution in toluene, and then methanol 500
After stirring for 10 minutes, the stirring was stopped, the content of the autoclave was transferred to a separate vessel having a volume of 2 liters, and the polymer (modified polybutadiene) was separated by filtration. Next, after dissolving the polymer in 800 ml of toluene, 800 ml of methanol was added to precipitate the polymer and the operation of filtration and separation was repeated three times, and then Irganox-1010 [tetrakis- (methylene- 3- (3,5-Di-t-butyl-4-hydroxyphenyl) propionate) methane]
0.11 phr with respect to the modified polybutadiene and 0.45 phr of tris (nonylphenyl) phosphite as an antioxidant were added and kneaded.
After drying under vacuum for a period of time, a modified polybutadiene was obtained.

Example 2 A modified polybutadiene was obtained in exactly the same manner as in Example 1 except that the modifier was changed to 3,5-diaminobenzoic acid.

Example 3 A modified polybutadiene was produced in exactly the same manner as in Example 1, except that the amount of the modifier, 4,4-diaminobenzoic acid, was changed to 1.8 mmol.

Example 4 A modified polybutadiene was produced in exactly the same manner as in Example 2, except that the amount of the modifier, 3,5-diaminobenzoic acid, was changed to 1.5 mmol.

Comparative Example 1 The same operation as in Example 1 was carried out, and after polymerization of 1,3-butadiene was performed at 60 ° C. for 30 minutes, the unreacted gas was immediately discharged without adding a modifier. After that, the same post-processing as in Example 1 is performed,
Unmodified polybutadiene was produced.

[Vulcanization properties] Polybutadiene (modified BR or unmodified BR) obtained in Examples 1 to 4 and Comparative Example 1
Were blended as shown in Table 1 to prepare rubber compositions. Then, the obtained formulation is heated at 150 ° C. for 30 minutes.
After press vulcanization for one minute, the physical properties of the vulcanized product were measured for the 300% elastic modulus, the rolling resistance index, the tensile strength, and the wet skid resistance by the above-mentioned methods, and the results are shown in Table 2.

[0050]

[Table 1] Table 1 配 Mixing amount (parts by weight) ────────────── {Modified BR or BR 70 NR 30 carbon black (ISAF) 45 zinc white (ZnO) 3 stearic acid 1 vulcanization accelerator * 1 sulfur 1.5} ────────── * N-tert.-butyl-2-benzothiazolylsulfenamide

[0051]

Table 2 Table 2 Example Comparative Example 1 1 2 3 4 ( (Undenatured) ───────────────────────────────── Nitrogen content (ppm) 250 240 340 310 Not detected -1,4 content (%) 98.2 98.3 98.3 98.2 98.2 Weight average molecular weight (million) 42.9 42.8 43.6 43.6 42.0 Molecular weight distribution 2.34 2.31 2.38 2.35 2.39 Mooney viscosity 35 35 36 36 33 Gel fraction (%) 33 34 37 35 30 cis -1,4 content (%) 98.2 98.3 98.3 98.2 98.2 ───────────────────────────────── 300% elastic modulus (MPa) 14 14 16 15 12 Rolling resistance index 108 106 112 111 100 Tensile strength (MPa) 22 21 19 20 19 Wet skid index 104 104 110 107 100 ──────────────── ─────────────────

[0052]

According to the present invention, 1,3-butadiene is converted to a cobalt-based catalyst composition comprising a cobalt compound, a halogen-containing organoaluminum compound and water, or a nickel-based catalyst composition comprising a nickel compound, an organoaluminum compound and a fluorine compound. After polymerization in the presence of a catalyst composition to form polybutadiene, modified polybutadiene (modified polybutadiene rubber) produced by a method of modifying this polybutadiene with an aromatic compound having at least two amino groups and one carboxyl group is It has realized an increase in Mooney viscosity, an increase in gel fraction, an increase in tensile strength, an improvement in rebound resilience (rolling resistance index), and an improvement in wet skid resistance, and are particularly useful as automotive tire materials.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuji Nakajima 8-1, Goi Minami Coast, Ichihara-shi, Chiba Ube Industries, Ltd. Chiba Petrochemical Plant (72) Inventor Kiyoshige Muraoka Tsutsui, Chuo-ku, Kobe-shi, Hyogo 2-1-1 Sumitomo Rubber Industries, Ltd. (72) Inventor Noriko Yagi 2-1-1 Tsutsui-cho, Chuo-ku, Kobe-shi, Hyogo F-term in Sumitomo Rubber Industries, Ltd. 4J002 AC01X AC11W AE053 FD010 GM02 GN01 4J028 AA01A AB00A AC47A AC48A BA00A BA01A BA01B BB00A BB01A BB01B BC15A BC15B BC16A BC16B BC17A BC17B BC19A BC19B CA17A CA17B CA17C CB22A CB22B CB22C CB27A CB27B CB27C CB94A CB94B CB94C EA01 EB02 EB04 EB05 EB13 EB16 EB17 FA09 GA01 GA04 GA11 4J100 AS02P CA01 CA31 DA01 DA09 FA08 FA12 HA61 HC27 HC43 JA29

Claims (7)

[Claims] 1. A 1,3-butadiene comprising a cobalt compound, a halogen-containing organoaluminum compound, and a cobalt-based catalyst composition comprising water or a nickel compound,
After polymerizing in the presence of a nickel-based catalyst composition comprising an organoaluminum compound and a fluorine compound into polybutadiene, the polybutadiene is modified with an aromatic compound having at least two amino groups and one carboxyl group. A method for producing a modified polybutadiene, comprising: 2. The catalyst composition to be used is a cobalt-based catalyst composition, and the amount of the catalyst component used is 1,
For 1 mol of 3-butadiene, 1 × 10 ⁻⁷ to 1 × 10 ⁻³ mol for the cobalt compound and 1 × 10 ⁻⁵ to 1 × 1 for the halogen-containing organoaluminum compound.
0 ^-1 mol, and 1 × 10 ⁻⁵ to 1 × 1 for water.
2. The method for producing a modified polybutadiene according to claim 1, wherein the amount is 0 ^-1 mol. 3. The method according to claim 1, wherein the cobalt compound has 1 to 18 carbon atoms.
3. The method for producing a modified polybutadiene according to claim 1, wherein the salt is a cobalt salt of a carboxylic acid. 4. The modified product according to claim 1, wherein the halogen-containing organoaluminum compound is a dialkylaluminum halide, alkylaluminum dihalide or alkylaluminum sesquihalide having a total of 2 to 10 carbon atoms. A method for producing polybutadiene. 5. The method according to claim 1, wherein the aromatic compound having at least two amino groups and one carboxyl group is 3,4-diaminobenzoic acid or 3,5-diaminobenzoic acid. A method for producing the modified polybutadiene as described above. 6. A modified polybutadiene obtained by the production method according to any one of claims 1 to 5, wherein 80% or more of its repeating units have a cis-1,4 structure, and have a Mooney structure. 20 viscosity (ML _{1 + 4} , 100 ° C)
A modified polybutadiene having a weight-average molecular weight by gel permeation of from 200,000 to 1,000,000 and a nitrogen content of from 10 to 5000 ppm. 7. A rubber composition comprising the modified polybutadiene according to claim 6 in a rubber component at least 10% by weight.