JP2001302703A - Preparation method of modified polybutadiene, modified polybutadiene, and rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a preparation method of a modified polybutadiene as a rubber component having low rolling resistance and excellent wet skid resistance when used as a rubber material for automobile tires. SOLUTION: A polybutadiene which is obtained by polymerizing 1,3-butadiene in the presence of a cobalt-based catalyst composition comprising a cobalt compound, a halogen-containing organic aluminium compound and water or a nickel-based catalyst composition comprising a nickel compound, an organic aluminum compound and a fluorine compound is modified with an organic silicon compound having at least an epoxy group and an alkoxy group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As a rubber for an automobile tire tread,
Conjugated diene copolymer rubbers such as polybutadiene and butadiene-styrene copolymer rubber are generally used. However, in recent years, due to the demand for low fuel consumption of automobiles and the demand for running stability on snow and ice, rubber materials having a lower rolling resistance and a larger road grip on snow and ice have been used as rubber for automobile tire treads. The emergence of is desired.

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. .

For example, JP-A-58-162604 and JP-A-59-117514 describe a method of modifying a rubber component by reacting it with benzophenone, and Japanese Patent Publication No. 6-53766. , Tokuhei 6-57
No. 769 and Japanese Patent Publication No. 6-78450 describe a method of modifying a rubber component by reacting it with a nitroamino compound, a nitro compound or a nitroalkyl compound.

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 low. 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, there are few proposals on a method for producing a modified polymer by adding a modifying agent to a polymerization system.

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 of obtaining a modified rubber having a high cis content without such a complicated operation by directly adding a modifying agent to the polymerization system.

As such a method, a method has been proposed in which a modifier is directly added to a conjugated diene polymer having a pseudo-living property 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. Also, JP-A-63-30
No. 5101 discloses a method similar to that described in US Pat.
A method for producing a modified conjugated diene polymer by adding a specific halogen compound such as 4,6-trichloro-1,3,5-triazine is described.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to the use of a modifier having high reactivity with polybutadiene produced in the presence of a cobalt-based catalyst composition or a nickel-based catalyst composition, particularly for automobile tires. It is a main object to provide a technique for producing a modified polybutadiene having excellent properties as a material for a tread.

[0010]

According to the present invention, 1,3-butadiene is prepared from a cobalt-based catalyst composition comprising a cobalt compound, a halogen-containing organoaluminum compound and water, or a nickel compound, an organoaluminum compound and a fluorine compound. An object of the present invention is to provide a method for producing a modified polybutadiene, which comprises modifying a polybutadiene polymerized in the presence of a nickel-based catalyst composition with an organosilicon compound having at least an epoxy group and an alkoxy group.

The organosilicon compound having at least an epoxy group and an alkoxy group used in the present invention is 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, or diethoxy-3.
-Glycidoxypropylmethylsilane is preferred.

The present invention also relates to a modified polybutadiene obtained by the above-mentioned production method, wherein
% Or more has a cis-1,4 structure, and has a Mooney viscosity (ML
_{1 + 4} , 100 ° C.) in the range of 20 to 80, and a weight average molecular weight by gel permeation of 200,000.
１，1,000,000 and the silicon content is 10
It provides modified polybutadiene in the range of 5,000 ppm.

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

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing a modified polybutadiene, a modified polybutadiene, and a rubber composition of the present invention will be described in detail.

As the cobalt compound as a component of the cobalt catalyst composition used in the production method of the present invention, 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, trisacetylacetonate, and ethyl acetoacetate; triarylphosphine complexes of cobalt halides; trialkylphosphine complexes; pyridine complexes and picoline complexes Various complexes such as an organic base complex and an ethyl alcohol complex are exemplified.

The halogen-containing organoaluminum compound as a component of the cobalt-based catalyst composition includes R
_3-n AlX _n (wherein, R represents a hydrocarbon group having 1 to 10 carbon atoms, X represents a halogen, and n is an integer of 1 to 2).
And a halogen-containing alkylaluminum compound represented by the following formula: 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 diethyl aluminum monochloride, diethyl aluminum mono bromide, dibutyl aluminum monochloride,
Ethyl aluminum sesquichloride, ethyl aluminum dichloride, dicyclohexyl aluminum monochloride, diphenyl aluminum monochloride and the like can be mentioned.

As the nickel compound as a component of the nickel-based catalyst composition used in the production method of the present invention, a salt or complex of nickel 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.

Examples of the organoaluminum compound as a component of the nickel-based catalyst composition include a trialkylaluminum represented by AlR ₃ (R represents a hydrocarbon group having 1 to 10 carbon atoms). . Examples thereof include trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, trioctylaluminum and trioctylaluminum. Examples thereof include phenyl aluminum, tri-p-tolyl aluminum, and tribenzyl aluminum. The three alkyl groups of the trialkylaluminum may be the same or different from each other.

The fluorine compound as a component of the nickel-based catalyst composition may be a complex of boron trifluoride ether, alcohol, or a mixture thereof, or a hydrogen fluoride ether, alcohol, or a complex of these complexes. A mixture is used. Particularly preferred fluorine compounds include boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, hydrogen fluoride diethyl etherate, and hydrogen fluoride dibutyl etherate.

In the process for producing the modified polybutadiene of the present invention, the amount of each catalyst component used is 1 to 1,3-butadiene when a cobalt-based catalyst composition comprising a cobalt compound, a halogen-containing organoaluminum compound and water is used.
1 × 10 ⁻⁷ to about 10 mol for the cobalt compound
It is preferably in the range of 1 × 10 ^-3 mol, 1 × 10 ^-5 ~1 × for halogen-containing organic aluminum compound
It is preferably in the range of 10 ^-1 mol, and for water, it is preferably in the range of 1 x 10 ^-5 to 1 x 10 ^-1 mol.

When a nickel-based catalyst composition comprising a nickel compound, an organoaluminum compound and a fluorine compound is used, 1 × 10 ^-7 to 1 mol of the nickel compound is used per mole of 1,3-butadiene. × 10
^-3 mol, preferably 1 × 10 ^-5 to 1 × 10 ^-1 mol for the organoaluminum compound, and 1 × 10 mol for the fluorine compound.
It is preferably in the range of ^-4 to 1 mol.

The order of addition of 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 production of polybutadiene, a known molecular weight regulator, for example, a non-conjugated diene such as cyclooctadiene or arene, or an α-olefin such as ethylene, propylene or butene-1 may be used during the polymerization reaction. Kinds can be used.

[0025] 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, after a polymerization of 1,3-butadiene, a modification reaction is performed by adding an organosilicon compound having at least an epoxy group and an alkoxy group used as a modifying agent.

As the organosilicon compound having at least an epoxy group and an alkoxy group used as a modifier in the present invention, 3-glycidoxypropyltrimethoxysilane,
Preferred is 3-glycidoxypropyltriethoxysilane or diethoxy-3-glycidoxypropylmethylsilane. These modifiers may be used alone,
Alternatively, a plurality of types may be used in combination.

The modifier is used in an amount of 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 is small, the modifying effect is less likely to appear. Also,
If the amount is too large, the unreacted modifier tends to remain in the polybutadiene, and it takes time and effort to remove it, which is not preferable.

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 the catalyst to be used is 0.01 to 50 mmol, preferably 0.05 to 30 mmol, more preferably 0.01 to 20 mmol, per 100 g of polybutadiene.

In the modified polybutadiene (modified butadiene rubber) of the present invention obtained by the above-mentioned production method of the present invention, 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 silicon content is 10 to 5000 ppm. , Especially 30 to
It is desirable to be in the range of 1000 ppm.

The modified polybutadiene obtained by the process of the present invention may be blended alone or blended with another synthetic rubber or natural rubber, if necessary, oil-extended with a process oil, and then a filler such as carbon black, Vulcanizing agents, vulcanization accelerators and other usual compounding agents are added and vulcanized to produce tires
Used for rubber applications requiring mechanical properties and abrasion resistance, such as hoses, belts and other various industrial products. Also,
It can also be used as a plastic modifier.

When the modified polybutadiene obtained by the production method of the present invention is used as a rubber material for an automobile tire tread, at least the modified polybutadiene of the present invention is contained in the rubber component in a rubber composition comprising a rubber component and a compounding agent. Is preferably added so as to contain 10% by weight.

[0034]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but these do not limit the present invention. The rubbery polymers obtained in the following Examples and Comparative Examples have Mooney viscosities (ML _{1 + 4} , 100 ° C.)
The 1,4-content, silicon content, weight average molecular weight, molecular weight distribution and gel fraction were measured by the following methods.

(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 (%): The cis-content was determined by measuring the polymer microstructure using a 0.4% by weight carbon disulfide solution by infrared absorption spectroscopy.
The 1,4-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, manufactured by Kyoto Koken Co., Ltd., UPP) -1 (MARK-II type) (unit: ppm).

(4) Weight average molecular weight and molecular weight distribution: obtained using gel permeation (permeation) chromatography (GPC, manufactured by Tosoh Corporation) at a temperature of 40 ° C. using polystyrene as a standard substance and tetrahydrofuran as a solvent. The weight-average molecular weight (Mw) and the number-average molecular weight (Mw) were calculated using a calibration curve obtained from the obtained molecular weight distribution curve.
n) was determined and expressed as molecular weight distribution (Mw / Mn). (5) Gel fraction: About 0.5 g of an unvulcanized rubber sample is taken, cut into small pieces, and its weight is measured accurately (Rg). 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 immersed in a stoppered bottle 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, further dried under reduced pressure at 70 ° C. for 24 hours to a constant weight, and the toluene-insoluble matter is accurately weighed together with the basket (Gg + Kg). The gel fraction was determined.

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 Total parts by weight of the rubber component (NR + modified BR or unmodified BR) in Table 1

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 strain of 10%, and a dynamic strain of 2%, and the rolling was calculated by the following equation. The resistance index was determined. A higher index value indicates a lower rolling resistance. 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-6251. (4) Wet skid resistance index: ASTM-E303- using a portable skid resistance meter manufactured by Stanley.
The measurement was carried out according to the method of Example 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,
C ₄ distillate containing 45.2% by weight of benzene -C ₄ fraction mixed l of solution (mainly containing benzene 40 wt% and cis-2-butene containing 1,3 butadiene 27.9 wt% ) Was added, and 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, 0.0087 mmol of cobalt octoate was added, and a polymerization reaction was performed at 60 ° C for 30 minutes. next,
Immediately at 60 ° C., 1.78 mmol of 3-glycidoxypropyltrimethoxysilane as a denaturant was added, and a denaturation reaction was performed at the same temperature for 120 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 contents of the autoclave were transferred to a separate vessel having a volume of 2 liters, and the polymer (modified polybutadiene) was separated by filtration. Next, an operation of dissolving the polymer with 800 ml of toluene, adding 800 ml of methanol to precipitate the polymer, and performing filtration and separation was repeated three times. Thereafter, Irganox-101 was used as an antioxidant.
0 [tetrakis- (methylene-3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionate) methane] with respect to the modified polybutadiene at 0.11 phr,
As an antiaging agent, 0.45 phr of tris (nonylphenyl) phosphate was added and kneaded, followed by vacuum drying at 100 ° C. for 1.5 hours to obtain a modified polybutadiene.

Example 2 A modified polybutadiene was obtained in exactly the same manner as in Example 1, except that the modifying agent was changed to the same amount of 3-glycidoxypropyltriethoxysilane.

Example 3 The same amount of diethoxy-
The same operation as in Example 1 was performed except that 3-glycidoxypropylmethylsilane was used, to obtain a modified polybutadiene.

Example 4 A modified polybutadiene was obtained in exactly the same manner as in Example 1 except that the amount of the modifier, 3-glycidoxypropyltrimethoxysilane, was changed to 3.0 mmol.

[Comparative Example 1] The same operation as in Example 1 was performed, 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,
An unmodified polybutadiene was obtained.

[Vulcanization Properties] Using each of the polybutadienes (modified BR or unmodified BR) obtained in Examples 1 to 4 and Comparative Example 1, rubber compositions were prepared according to the formulations shown in Table 1. Next, the obtained rubber composition was
Press-vulcanized at 50 ° C. for 30 minutes to determine the physical properties of the vulcanized product according to the above-mentioned method, 300% elastic modulus, rolling resistance index,
The tensile strength and wet skid resistance index were measured and are shown in Table 2.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

According to the process for producing the modified polybutadiene of the present invention, the Mooney viscosity is increased, the gel fraction is increased, the tensile strength is increased, and the rebound resilience (rolling resistance index) is improved. A modified polybutadiene (modified butadiene rubber) having high utility as a tire material can be produced.

 ──────────────────────────────────────────────────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. 4J028 AA01A AB00A AC47A AC48A BA00A BA01B BB00A BB01B CA32C CB12C EB13 EC01 FA01 FA02 GA01 GA11 4J100 AS02P BA77H CA01 DA01 DA09 HA55 HC78 HE41 JA29

Claims (4)

[Claims] 1. A method for preparing 1,3-butadiene from 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. A method for producing a modified polybutadiene, characterized in that the polybutadiene polymerized in (1) is modified with an organosilicon compound having at least an epoxy group and an alkoxy group. 2. The organic silicon compound having at least an epoxy group and an alkoxy group is 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, or diethoxy-3-glycidoxypropylmethylsilane. The method for producing a modified polybutadiene according to claim 1, wherein 3. A modified polybutadiene obtained by the method according to claim 1 or 2, wherein 80% or more of the 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,
Weight average molecular weight of 20 by gel permeation method
A modified polybutadiene having a silicon content in a range of 000 to 1,000,000 and a silicon content of 10 to 5,000 ppm. 4. A rubber composition comprising the modified polybutadiene according to claim 3 in a rubber component at least 10% by weight.