JP3759850B2 - Process for producing modified polybutadiene - Google Patents

Description

【００５０】
【発明の効果】
本発明に従って、１，３−ブタジエンを、コバルト化合物、ハロゲン含有有機アルミニウム化合物、及び水からなるコバルト系触媒組成物の存在下で重合させてポリブタジエンとした後、このポリブタジエンをオルガノアルコキシシランあるはオルガノアロキシシランを用いて変性する方法により製造した変性ポリブタジエン（変性ポリブタジエンゴム）は、ムーニー粘度の増加、ゲル分率の増加、引張強度の増加、反発弾性率（転がり抵抗指数）の向上、そしてウエットスキッド抵抗の向上が実現しており、特に自動車タイヤ材料として有用性が高い。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a modified polybutadiene particularly useful as a rubber material for tire treads and a rubber composition useful as a rubber material for tire treads.
[0002]
[Prior art]
As rubbers for automobile tire treads, conjugated diene copolymer rubbers such as polybutadiene and butadiene-styrene copolymer rubber are generally used. However, in recent years, due to demands for reducing fuel consumption of automobiles and demands for running stability on snow and ice, rubber materials with even lower rolling resistance and greater road surface grip on snow and ice are required as rubber for automobile tire treads. The appearance of is desired.
[0003]
As means for solving this problem, many methods for introducing a specific atomic group into a polymer by reacting, for example, an alkali metal-containing diene polymer with a specific compound have been proposed.
[0004]
Japanese Patent Application Laid-Open Nos. 58-162604 and 59-117514 describe methods for modifying rubber components by reacting with benzophenone, and Japanese Patent Publication Nos. 6-53766 and 6-61. Japanese Patent No. 57769 and Japanese Patent Publication No. 6-78450 describe a method in which a rubber component is modified by reacting with a nitroamino compound, a nitro compound or a nitroalkyl compound.
[0005]
However, these methods currently do not provide a sufficiently satisfactory rubber material, and furthermore, the rubber materials obtained by these methods have a low cis-1,4 content in the microstructure of the polymer, There was a problem that the abrasion resistance was inferior to that of the high cis polymer. On the other hand, Co catalysts, Ni catalysts, Ti catalysts, Nd catalysts, and the like are known as catalysts that give high-cis polymers. Among these catalysts, Co catalysts, Ni catalysts, and Ti catalysts have living properties. Therefore, there are few proposals for a method for producing a modified polymer by adding a modifier to the polymerization system.
[0006]
A method for producing a modified polymer by adding a solvent to a high cis polymer and dissolving it, and bringing a catalyst and a modifier into contact with the solution is already known. For example, in Japanese Patent Application Laid-Open No. 58-142901, rubber is dissolved in a solvent, and an organic compound having a carboxyl group and an aldehyde group is reacted with the rubber having an unsaturated bond in the presence of an acid catalyst. A method of performing denaturation has been proposed. Japanese Patent Application Laid-Open No. 58-162602 proposes a method in which a rubber is dissolved in a solvent, and an organic compound having a carboxyl group and an aromatic sulfonehaloamide salt are reacted with a rubber having an unsaturated bond.
[0007]
JP-A-61-225202 describes a method of modifying a rubber by dissolving a rubber having an unsaturated bond in a solvent and reacting with benzylidenebutylamine or an organic acid halide in the presence of a Lewis acid. . Any of these methods requires a step of forming a rubber solution obtained by dissolving rubber with a solvent, and requires 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 adding a modifying agent directly to the polymerization system.
[0008]
As such a method, a method of directly adding a modifier to a conjugated diene polymer having pseudo-living properties produced using an Nd catalyst has been proposed. For example, in JP-A-63-178102, a conjugated diene is polymerized using a lanthanum series rare earth metal catalyst, and a modified halogenated organic metal is reacted with a polymer immediately after the polymerization to react with a specific halogenated organic metal. A method for producing coalescence is described. In JP-A-63-297403, a conjugated diene is polymerized using a lanthanum series rare earth metal catalyst, and a specific heterocumulene compound or a hetero three-membered ring compound is reacted with the polymer immediately after the polymerization. A method for producing a modified conjugated diene polymer has been proposed. JP-A-63-305101 discloses a modified conjugated diene by adding a specific halogen compound such as 2,4,6-trichloro-1,3,5-triazine as a modifying agent in the same manner. A method for producing a polymer is described.
[0009]
[Problems to be solved by the invention]
The present invention is a technique for producing a modified polybutadiene having excellent properties particularly as a material for a tire tread of an automobile, using a modifier exhibiting high reactivity with polybutadiene produced in the presence of a cobalt compound-containing catalyst composition. The main purpose is to provide
[0010]
[Means for Solving the Problems]
In the present invention, 1,3-butadiene is polymerized in the presence of a cobalt-based catalyst composition composed of a cobalt compound, a halogen-containing organoaluminum compound, and water to form polybutadiene. Subsequently, the polybutadiene is converted to organoalkoxysilane. More than 80% of the repeating units have a cis-1,4 structure, Mooney viscosity (ML _{1 + 4} , 100 ° C.) is in the range of 20-80, and the weight by gel permeation method The average molecular weight is in the range of 200,000 to 1,000,000 and the method for producing modified polybutadiene having a silicon content in the range of 10 to 5000 ppm.
[0011]
Is an organoalkoxysilane Sila down for use in the present invention is preferably a compound represented by the following formula.
[0012]
[Chemical 2]
R ¹ _n Si (OR ² ) _4-n
[0013]
[Wherein, R ¹ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms, and R ² represents carbon Represents an alkyl group having 1 to 10 atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms, and n is an integer of 0 to 3].
[0014]
The present invention also resides in a rubber composition characterized in that the rubber component contains at least 10% by weight of the modified polybutadiene obtained by the above production method .
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The method for producing the modified polybutadiene of the present invention and the use of the modified polybutadiene as a rubber material for a tire tread will be described in detail.
[0016]
As a cobalt compound in the case of using a cobalt-based catalyst composition, 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 carboxylic acid having 1 to 18 carbon atoms such as cobalt octylate, cobalt acetate and cobalt octoate, Cobalt naphthenate, cobalt malonate, cobalt bisacetylacetonate, trisacetylacetonate, acetoacetic acid ethyl ester, etc., cobalt halide triarylphosphine complex, trialkylphosphine complex, pyridine complex, picoline complex, etc. Various complexes, such as an organic base complex or an ethyl alcohol complex, are mentioned.
[0017]
As the halogen-containing organoaluminum compound in the case of using the cobalt-based catalyst composition, R _3-n AlX _n (wherein R represents a hydrocarbon group having 1 to 10 carbon atoms, X represents a halogen, and n represents 1 to 1). A halogen-containing alkylaluminum compound represented by formula (2). Examples thereof include dialkylaluminum halides such as dialkylaluminum chloride and dialkylaluminum bromide, alkylaluminum sesquichlorides such as alkylaluminum sesquichloride, alkylaluminum sesquibromides, alkylaluminum dihalides such as alkylaluminum dichloride and alkylaluminum dibromide, and the like. Can be mentioned. Specific examples of the compound include diethyl aluminum monochloride, diethyl aluminum monobromide, dibutyl aluminum monochloride, ethyl aluminum sesquichloride, ethyl aluminum dichloride, dicyclohexyl aluminum monochloride, diphenyl aluminum monochloride.
[0018]
The amount of cobalt compound used in the cobalt-based catalyst composition used in the production of polybutadiene is such that the cobalt compound is in the range of 1 × 10 ⁻⁷ to 1 × 10 ⁻³ mol with respect to 1 mol of 1,3-butadiene as the raw material monomer. Is preferred. The amount of halogen-containing organoaluminum compound used is in the range of 1 × 10 ⁻⁵ to 1 × 10 ⁻¹ mol per mol of cobalt compound, and the amount of water used is 1 × per mol of cobalt compound. It is preferably in the range of 10 ⁻⁵ to 1 × 10 ⁻¹ mol.
[0019]
There is no restriction | limiting in the addition order of the catalyst component to a reaction system. Each catalyst component can be added simultaneously or in any order.
[0020]
There is no restriction | limiting in particular also about the polymerization method, The polymerization method generally utilized about 1, 3- butadiene, such as block polymerization and solution polymerization, can be utilized. Solvents for 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, -Use olefinic hydrocarbons such as butene, cis-2-butene, trans-2-butene, hydrocarbon solvents such as mineral spirit, solvent naphtha, kerosene, halogenated hydrocarbon solvents such as methylene chloride, etc. it can. Further, 1,3-butadiene itself may be used as a polymerization solvent. Among these, benzene, cyclohexane, or a mixture of cis-2-butene and trans-2-butene is preferably used as a solvent for solution polymerization.
[0021]
In carrying out the polymerization reaction for the production of polybutadiene, known molecular weight regulators, for example, non-conjugated dienes such as cyclooctadiene and allene, or α-olefins such as ethylene, propylene and butene-1 are used. can do.
[0022]
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 pressure is carried out at normal pressure or under a pressure up to about 10 atmospheres (gauge pressure).
[0023]
In preparing the modified polybutadiene of the present invention, after polymerization of 1,3-butadiene, by adding organoalkoxysilane Sila down to be used as a modifier performs modification reaction.
[0024]
Organoalkoxysilanes Sila emissions used as modifiers in the present invention is preferably a compound represented by the following formula.
[0025]
[Chemical 3]
R ¹ _n Si (OR ² ) _4-n
[0026]
[Wherein, R ¹ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms, and R ² represents carbon Represents an alkyl group having 1 to 10 atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms, and n is an integer of 0 to 3].
[0027]
Examples of specific compounds of the organoalkoxysilane Sila emission represented by the above general formula, ethyltrimethoxysilane, triethoxysilane, butyl trimethoxysilane, methyltriethoxysilane, tetraethoxysilane, triethoxysilane, phenyl tri Methoxysilane, hexyltrimethoxysilane, tetrabutoxysilane, tetraphenoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, pentyltriethoxysilane, phenyltriethoxysilane, octyltriethoxysilane, tripentyloxysilane, tetramethoxysilane , Ethoxytrimethylsilane, diethoxydimethylsilane, butoxytrimethylsilane, isobutoxytrimethylsilane, 1-methylpropoxytrimethylsilane, tert- Mention may be made of butoxytrimethylsilane, butoxytrimethylsilane, dimethyldipropoxysilane, diethoxydiethylsilane, and methoxytripropylsilane. Of these compounds, tetramethoxysilane, methyltrimethoxysilane, and tetraethoxysilane are particularly preferable. These modifiers may be used alone or in combination of two or more.
[0028]
The amount of the modifier used is 0.01 to 150 mmol, preferably 1 to 100 mmol, more preferably 3 to 50 mmol, based on 100 g of polybutadiene (polybutadiene rubber) produced by polymerization. If the amount of the modifying agent used is small, the modification effect is difficult to appear. Moreover, when there is too much usage-amount, an unreacted modifier will remain easily in polybutadiene, and it takes time and effort to remove it, which is not preferable.
[0029]
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, the modification reaction is preferably performed at the same temperature as the polymerization temperature. The modification time is not particularly limited, but is usually preferably in the range of 0.5 to 6 hours. If the modification time is too short, the reaction does not proceed sufficiently, and if the modification time is too long, the polymer may be gelled.
[0030]
Further, immediately after the polymerization of 1,3-butadiene, prior to the addition of the modifier, a catalyst such as an aluminum halide or an alkyl halide (the alkyl group has 1 to 6 carbon atoms) is used to accelerate the progress of the modification reaction. It can also be added as. 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 the catalyst used is 0.01-50 mmol, preferably 0.05-30 mmol, more preferably 0.1-20 mmol, per 100 g of polybutadiene.
[0031]
The modified polybutadiene (modified polybutadiene rubber) of the present invention obtained by the above production method has a cis-1,4 structure in 80% or more of the repeating units, and has a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 20 to 20%. It is preferably in the range of 80, the weight average molecular weight by the gel permeation method is in the range of 200,000 to 1,000,000, and the silicon content is preferably in the range of 10 to 5000 ppm (particularly 30 to 1000 ppm). .
[0032]
The modified polybutadiene obtained by the present invention is blended alone or blended with other synthetic rubber or natural rubber, and if necessary, is oil-extended with process oil, and then a filler such as carbon black, a vulcanizing agent, Vulcanization accelerators and other ordinary compounding agents are added to vulcanize and used for rubber applications that require mechanical properties and wear resistance, such as tires, hoses, belts, and other various industrial products. It can also be used as a plastic modifier.
[0033]
When the modified polybutadiene obtained by the present invention is used as a rubber material for an automobile tire tread, the rubber composition comprising the rubber component and the compounding agent contains at least 10% by weight of the modified polybutadiene of the present invention in the rubber component. It is preferable to blend so as to.
[0034]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, these do not limit this invention. The 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 rubber-like polymers obtained in the following Examples and Comparative Examples The rate was measured by the following method.
[0035]
(1) Mooney viscosity (ML _{1 + 4} , 100 ° C.): In accordance with JIS-K6300, using a Mooney viscometer (SMV-200) manufactured by Shimadzu Corporation, preheat at 100 ° C. for 1 minute, and then for 4 minutes. It was measured and expressed as the Mooney viscosity of 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 spectrum analysis, cis-1,4- The content was calculated.
(3) Silicon content (ppm): The sample was dry ashed by sulfuric acid decomposition, the ash was alkali-melted with sodium carbonate, and inductively coupled high-frequency plasma atomic emission method (ICP-AES, Kyoto Koken Co., Ltd., UPP- 1-MARK-II type) (unit: ppm).
[0036]
(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 material and tetrahydrofuran as a solvent, and from the obtained molecular weight distribution curve. The weight average molecular weight (Mw) and the number average molecular weight (Mn) were calculated using the obtained calibration curve, and displayed by molecular weight distribution (Mw / Mn).
(5) Gel fraction: About 0.5 g of an unvulcanized rubber sample is taken, finely cut, and its weight is accurately measured (Rg). The weight of a separately prepared 100 mesh stainless steel basket is precisely weighed (Kg), and the weighed sample is transferred to the cage, and the weight is measured (Rg + Kg). This is immersed in a bottle with a stopper containing 100 mL of toluene and left at 23 ° C. for 24 hours. Next, the basket is pulled up, dried at 23 ° C. for 24 hours, and then dried under reduced pressure for 24 hours so as to become a constant weight at 70 ° C., and the toluene-insoluble matter is accurately weighed together with the cage (Gg + Kg). The gel fraction was determined.
[0037]
Gel fraction (%) = 100 × [G− (R × (filler part by weight / total weight of rubber composition)] / [(R × (part by weight of rubber / total weight of rubber composition)]]
However,
Part by weight of filler: part by weight of carbon black in Table 1 Total part by weight of rubber composition: total part by weight of all components in Table 1 Rubber part by weight: total weight of rubber component (NR + BR or modified BR) in Table 1 Department [0038]
In addition, 300% elastic modulus, rolling resistance index, tensile strength, and wet skid resistance index were measured by the following methods.
(1) 300% elastic modulus (M ₃₀₀ ): measured by the method defined in JIS-K6301, and indicated by a modulus at 300%.
(2) Rolling resistance index: Using a viscoelastic spectrometer VES manufactured by Iwamoto Seisakusho Co., Ltd., tan δ is measured under the conditions of a temperature of 70 ° C., an initial strain of 10%, and a dynamic strain of 2%. The resistance index was determined. A larger index value means lower rolling resistance. The rolling resistance may be 100 or more.
[0039]
Rolling resistance index = 100 × [(value of comparative example (unmodified product)) / (value of example (modified product))]
[0040]
(3) Tensile strength: measured in accordance with JIS-K-6251.
(4) Wet skid resistance index: Measured according to the method of ASTM-E303-83 using a portable skid resistance meter manufactured by Stanley. It shows that it is so favorable that a numerical value is large with the parameter | index of the grip characteristic (driving performance, braking performance, and steering performance) on the wet road surface.
[0041]
[Example 1]
In a 1.5 liter stainless steel autoclave sufficiently purged with nitrogen inside, 1 liter of a benzene-C ₄ fraction mixed solution containing 27.9% by weight of 1,3-butadiene (26.9% by weight of benzene, cis-2-butene were charged C ₄ fraction and 45.2 wt% containing) mainly composed of, then water 2 mmol, agitating by adding diethylaluminum monochloride 2.9 mmol, cyclooctadiene 4.24 mmol was added. After the temperature of the autoclave was raised and the internal temperature reached 58.5 ° C., 0.0087 mmol of cobalt octoate was added, and a polymerization reaction was performed at 60 ° C. for 30 minutes. Next, 2.0 mmol of tetramethoxysilane was added as a modifier, and a modification reaction was performed at the same temperature for 120 minutes.
[0042]
After completion of the reaction, the unreacted gas is discharged out of the system, 500 ml of toluene is added to make a toluene solution of the modified polybutadiene, 500 ml of methanol is further added, the mixture is stirred for 10 minutes, the stirring is stopped, and the autoclave is stopped. The contents were transferred to a separate container having a volume of 2 liters, and the polymer (modified polybutadiene) was separated by filtration. Next, the polymer was dissolved in 800 ml of toluene, and then 800 ml of methanol was added to precipitate the polymer, followed by filtration and separation three times. Thereafter, Irganox-1010 [tetrakis- (methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) methane] as an antioxidant is 0.11 phr with respect to the modified polybutadiene, an antioxidant. As described above, 0.45 phr of tris (nonylphenyl) phosphite was added and kneaded, followed by vacuum drying at 100 ° C. for 1.5 hours to obtain modified polybutadiene.
[0043]
[Example 2]
Except that the modifying agent was changed to the same amount of methyltriethoxysilane, the same operation as in Example 1 was performed to obtain a modified polybutadiene.
[0044]
[Example 3]
Except that the modifier was changed to the same amount of tetraethoxysilane, the same operation as in Example 1 was performed to obtain a modified polybutadiene.
[0045]
[Example 4]
A modified polybutadiene was produced in exactly the same manner as in Example 1 except that the amount of the modifying agent tetramethoxysilane was changed to 3.0 mmol.
[0046]
[Comparative Example 1]
The same operation as in Example 1 was performed, and after 1,3-butadiene was polymerized at 60 ° C. for 30 minutes, the unreacted gas was immediately discharged without adding a modifier, and thereafter the same as in Example 1 After treatment, unmodified polybutadiene was produced.
[0047]
[Vulcanized properties]
Each of the polybutadienes (modified BR or unmodified BR) obtained in Examples 1 to 4 and Comparative Example 1 was blended as shown in Table 1 to prepare a rubber composition. Next, the obtained compound was press vulcanized at 150 ° C. for 30 minutes, and as a physical property of the vulcanized product, the 300% elastic modulus, rolling resistance index, tensile strength, and wet skid resistance were measured by the above methods. The results are shown in Table 2.
[0048]
[Table 1]
Table 1 ─────────────────────
Compounding amount (parts by weight)
─────────────────────
Modified BR or BR 70
NR 30
Carbon black (ISAF) 45
Zinc flower (ZnO) 3
Stearic acid 1
Vulcanization accelerator * 1
Sulfur 1.5
─────────────────────
* N-tert-butyl-2-benzothiazolylsulfenamide
[Table 2]

[0050]
【The invention's effect】
In accordance with the present invention, 1,3-butadiene is polymerized in the presence of a cobalt-based catalyst composition comprising a cobalt compound, a halogen-containing organoaluminum compound, and water to form polybutadiene, which is then converted to an organoalkoxysilane or organo Modified polybutadiene (modified polybutadiene rubber) manufactured by a method modified with alloxysilane has increased Mooney viscosity, increased gel fraction, increased tensile strength, improved impact resilience (rolling resistance index), and wet skid. The resistance has been improved and is particularly useful as an automobile tire material.

Claims (2)

1,3-butadiene is polymerized in the presence of a cobalt-based catalyst composition comprising a cobalt compound, a halogen-containing organoaluminum compound, and water to form polybutadiene, and then the polybutadiene is modified with organoalkoxysilane. wherein, more than 80% of the repeating units having a cis-1,4 structure, there Mooney viscosity _{(ML 1 + 4, 100 ℃} ) is in the range of 20 to 80, weight average molecular weight by gel permeation method 200 A method for producing a modified polybutadiene having a silicon content in the range of 10 to 5000 ppm. Organoalkoxysilanes sila down the process of producing modified polybutadiene according to claim 1, characterized in that a compound represented by the following general formula:
[Chemical 1]
R ¹ _n Si (OR ² ) _4-n
[Wherein, R ¹ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms, and R ² represents carbon Represents an alkyl group having 1 to 10 atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms, and n is an integer of 0 to 3].