JP2017132958A - Rubber composition and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition excellent in low fuel consumption and a tire using the same.SOLUTION: There are provided a rubber composition by blending (C) a rubber reinforcement agent of 10 to 100 pts.wt. based on 100 pts.wt. of a rubber component (A)+(B) consisting of 10 to 90 pts.wt. of a vinyl cis-polybutadiene rubber (A) containing 1,2-polybutadiene having the melting point of 60 to 150°C (A) of 1 to 20 wt.% and 1,2-polybutadiene having the melting point of 160 to 197°C (B) of 1 to 25 wt.% and having percentage content of a graft body of 5 to 25 wt.% and 90 to 10 pts.wt. of a diene rubber (B) other than (A), and a tire using the same.SELECTED DRAWING: None

Description

  The present invention relates to a rubber composition and a tire using the rubber composition. More specifically, the present invention relates to a rubber composition using vinyl cis-polybutadiene rubber and a tire using the rubber composition.

  Conventionally, vinyl cis-polybutadiene rubber has been produced by converting 1,3-butadiene into cis-1, using a predetermined catalyst in an inert organic solvent mainly composed of hydrocarbons such as benzene, toluene and xylene. 4 polymerization, and then syndiotactic-1,2 polymerization (hereinafter sometimes simply referred to as “1,2 polymerization”).

  In addition, vinyl cis-polybutadiene rubber is desired to be improved in various properties depending on the use of the rubber composition. For example, in Patent Document 1, when 1,3-butadiene is polymerized in cis-1,4, when a rubber composition is prepared by previously mixing dissolved 1,2-polybutadiene, the extrudability is increased. And vinyl cis-polybutadiene rubber with improved tensile stress are described. Further, Patent Documents 2 to 4 describe vinyl cis-polybutadiene rubbers that are further improved and have excellent exothermic properties and resistance to stretch fatigue.

JP 2008-163144 A JP 2012-207052 A JP 2012-214735 A JP 2012-214765 A

  However, in the vinyl cis-polybutadiene rubbers described in Patent Documents 1 to 4, which are various improved vinyl cis-polybutadiene rubbers, when a rubber composition for a tire is used, other fuel efficiency such as low fuel consumption can be obtained. Regarding physical properties, there is still room for improvement.

  The present invention has been made in view of the above problems, and an object thereof is to provide a rubber composition excellent in low fuel consumption and a tire using the rubber composition.

  As a result of intensive studies to achieve the above object, the present inventors have incorporated 1,2-polybutadiene having a specific melting point into the vinyl cis-polybutadiene rubber compounded in the rubber composition, and grafted. The inventors have found that a rubber composition having excellent fuel efficiency can be produced by adjusting the body content, and have reached the present invention.

  That is, the present invention is 1 to 20% by weight of 1,2-polybutadiene (A) having a melting point of 60 to 150 ° C. and 1 to 25% by weight of 1,2-polybutadiene (B) having a melting point of 160 to 197 ° C. The vinyl cis-polybutadiene rubber (A) is 10 to 90 parts by weight and the diene rubber (B) other than (A) is 90 to 10 parts by weight. The present invention relates to a rubber composition comprising 10 to 100 parts by weight of a rubber reinforcing agent (C) per 100 parts by weight of a rubber component (A) + (B), and a tire using the rubber composition.

  As described above, according to the present invention, it is possible to provide a rubber composition excellent in fuel efficiency and a tire using the rubber composition.

<Vinyl cis-polybutadiene rubber (A)>
The vinyl cis-polybutadiene rubber (A) used in the rubber composition of the present invention contains 1 to 20% by weight of 1,2-polybutadiene (a) having a melting point of 60 to 150 ° C. in polybutadiene as a matrix component, and 1 to 25% by weight of 1,2-polybutadiene (b) having a melting point of 160 to 197 ° C. is contained, and the graft body content is 5 to 25% by weight.

(1,2-polybutadiene (a))
In the vinyl cis-polybutadiene rubber (A) according to the present invention, the melting point of 1,2-polybutadiene (a) is 60 to 150 ° C, preferably 80 to 120 ° C, and preferably 95 to 99 ° C. More preferably. If the melting point of 1,2-polybutadiene (a) is lower than 60 ° C or higher than 150 ° C, the crack resistance deteriorates, which is not preferable.

  The content of 1,2-polybutadiene (a) is 1 to 20% by weight, preferably 2 to 10% by weight, more preferably 3 to 7% by weight based on the vinyl cis-polybutadiene rubber (A). . When the content is more than 20% by weight, the fuel efficiency is deteriorated, and when the content is less than 1% by weight, the crack resistance is deteriorated.

  1,2-polybutadiene (a) is produced by adding or synthesizing vinyl cis-polybutadiene rubber (a) in an inert organic solvent in the first step of the method for producing vinyl cis-polybutadiene rubber (A) described later. The above content can be contained in the polybutadiene rubber (A). For example, when 1,2-polybutadiene (a) is added or synthesized in the third step, a graft body is not generated and crack resistance deteriorates, which is not preferable.

(1,2-polybutadiene (b))
In the vinyl cis-polybutadiene rubber (A) used in the present invention, the melting point of 1,2-polybutadiene (b) is 160 to 197 ° C, preferably 170 to 195 ° C, and preferably 175 to 190 ° C. More preferably. If the melting point of 1,2-polybutadiene (b) is lower than 160 ° C., the die swell is deteriorated, which is not preferable. If it is higher than 197 ° C., the fuel efficiency is deteriorated.

  The content of 1,2-polybutadiene (b) is 1 to 25% by weight, preferably 5 to 20% by weight, and more preferably 10 to 15% by weight based on the vinyl cis-polybutadiene rubber (A). . If the content is more than 25% by weight, the fuel efficiency is deteriorated, which is not preferable. If the content is less than 1% by weight, the crack resistance is deteriorated, which is not preferable.

  1,2-polybutadiene (b) is produced by syndiotactic-1,2 polymerization of 1,3-butadiene in the third step of the method for producing vinyl cis-polybutadiene rubber (A) described later. The above content can be contained in the vinyl cis-polybutadiene rubber (A).

  The peak top molecular weight (Mp) of 1,2-polybutadiene (b) is preferably from 5,000 to 300,000, more preferably from 20,000 to 150,000. When the peak top molecular weight (Mp) is larger than 300,000, the compound Mooney viscosity tends to be high and the processability tends to deteriorate, and when it is smaller than 5,000, the die swell tends to deteriorate. In the present invention, the peak top molecular weight (Mp) is the molecular weight of the peak top in an elution curve obtained by gel permeation chromatography (GPC) measurement, and can be calculated from a calibration curve obtained using polystyrene as a standard substance. .

(Polybutadiene)
In the vinyl cis-polybutadiene rubber (A) used in the present invention, the polybutadiene which is a matrix component is converted into 1,3-butadiene in the second step of the vinyl cis-polybutadiene rubber (A) described later. It is obtained by 1,4 polymerization. The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the polybutadiene is preferably 20 to 60, and more preferably 25 to 45. Further, the cis-1,4 structure content of polybutadiene is preferably 90% or more, and particularly preferably 95% or more.

  Moreover, the weight average molecular weight of the polybutadiene which is a matrix component is preferably 200,000 to 800,000, more preferably 400,000 to 650,000. Moreover, 2.00-5.00 are preferable and, as for ratio (Mw / Mn) of a weight average molecular weight and a number average molecular weight, 2.20-3.50 are more preferable.

  Moreover, the polybutadiene obtained by cis-1,4 polymerization contains substantially no gel content.

(Graft)
Furthermore, the vinyl cis-polybutadiene rubber (A) used in the present invention has a graft content of 5 to 25% by weight, preferably 15 to 22% by weight. The graft product is obtained by subjecting 1,3-butadiene to cis-1,4 polymerization in dissolved 1,2-polybutadiene (a), 1,2-polybutadiene (a), and polybutadiene as a matrix component. Is a partially chemically bonded substance. When the graft body content is 5 to 25% by weight, the fuel efficiency is good, and it is preferable from the viewpoint of balance with crack resistance.

<Method for producing vinyl cis-polybutadiene rubber (A)>
As a method for producing the vinyl cis-polybutadiene rubber (A) used in the present invention, 1,2-polybutadiene (a) having a melting point of 60 to 150 ° C., 1,3-butadiene, and hydrocarbons as main components are used. A first step of preparing a mixture with an inert organic solvent, and a mixture comprising water, an organoaluminum compound and a soluble cobalt compound, or an organoaluminum compound, a nickel compound and a fluorine compound in the mixture prepared in the first step Addition of catalyst to cis-1,4 polymerization of 1,3-butadiene, and syndiotactic-1,2 polymerization of 1,3-butadiene in the polymerization reaction mixture obtained in the second step And a third step of adding a melting point depressant that lowers the melting point of the resulting 1,2-polybutadiene (b) in the third step.

(First step)
The 1,2-polybutadiene (a) having a melting point of 60 to 150 ° C. used in the method for producing the vinyl cis-polybutadiene rubber (A) used in the present invention is a cobalt compound, general formula AlR ₃ (where R is carbon An organoaluminum compound and carbon disulfide represented by the formula (1 to 10 hydrocarbon groups), and alcohol, aldehyde, ketone, ester, nitrile, sulfoxide, amide, and phosphate ester as necessary. It is produced by polymerizing 1,3-butadiene using a catalyst comprising one or two or more selected compounds. The 1,2-polybutadiene (a) has a 1,2 structure content of preferably 40 to 99%, particularly preferably 50 to 95%. The 1,2-polybutadiene (a) is preferably syndiotactic-1,2-polybutadiene.

  In the method for producing the vinyl cis-polybutadiene rubber (A) used in the present invention, the amount of 1,2-polybutadiene (a) added is 1 to 20% by weight based on the obtained vinyl cis-polybutadiene (A). 2 to 15% by weight is preferable, and 3 to 10% by weight is more preferable. If the amount added is more than 20% by weight, the fuel efficiency tends to deteriorate, and if it is less than 1% by weight, the crack resistance tends to deteriorate, such being undesirable.

  Examples of the inert organic solvent used in the method for producing the vinyl cis-polybutadiene rubber (A) used in the present invention include aromatic hydrocarbons such as toluene, benzene and xylene, and fats such as n-hexane, butane, heptane and pentane. Hydrocarbons, alicyclic hydrocarbons such as cyclohexane and cyclopentane, the above olefin compounds and olefinic hydrocarbons such as cis-2-butene and trans-2-butene, hydrocarbons such as mineral spirits, solvent naphtha and kerosene And halogenated hydrocarbon solvents such as methylene chloride. Further, 1,3-butadiene monomer itself may be used as a polymerization solvent.

  Among the above inert organic solvents, toluene, cyclohexane, and a mixture of cis-2-butene and trans-2-butene are preferably used.

  In the method for producing the vinyl cis-polybutadiene rubber (A) used in the present invention, 1,2-polybutadiene (a) having a melting point of 60 to 150 ° C., 1,3-butadiene, and a hydrocarbon as a main component. The mixture with the active organic solvent can be prepared by dissolving 1,2-polybutadiene (a) in a mixture with 1,3-butadiene and the inert organic solvent. When 1,2-polybutadiene (a) is difficult to dissolve, it can be dissolved by heating to 30 to 180 ° C. Alternatively, a mixture may be prepared by synthesizing and dissolving 1,2-polybutadiene (a) in the mixture of 1,3-butadiene and an inert organic solvent using the above catalyst system.

(Second step)
Next, the concentration of moisture in the mixture adjusted in the first step is adjusted. The water concentration is preferably in the range of 0.1 to 1.4 mol, particularly preferably 0.2 to 1.2 mol, per mol of the organoaluminum compound used in the cis-1,4 polymerization. Outside this range, the catalytic activity is lowered, the cis-1,4 structure content is lowered, and the molecular weight is abnormally low or high. Further, outside the above range, it is not preferable because the generation of gel during polymerization cannot be suppressed, so that the gel adheres to the polymerization tank and the continuous polymerization time cannot be extended. A known method can be applied as a method of adjusting the moisture concentration. A method of adding and dispersing through a porous filter medium (Japanese Patent Laid-Open No. 4-85304) is also effective.

  An organoaluminum compound is added to the mixture obtained by adjusting the water concentration as described above. Examples of the organoaluminum compound include trialkylaluminum, dialkylaluminum chloride, dialkylaluminum bromide, alkylaluminum sesquibromide, alkylaluminum sesquibromide, and alkylaluminum dichloride.

Of the above organoaluminum compounds, trialkylaluminum represented by the general formula AlR ₃ (where R is a hydrocarbon group having 1 to 10 carbon atoms) can be preferably used. Examples of trialkylaluminums include trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, trioctyl Mention may be made of aluminum, triphenylaluminum, tri-p-tolylaluminum and tribenzylaluminum. The alkyl groups in the trialkylaluminum may be the same as or different from each other.

  In addition to the above organoaluminum compounds, dialkylaluminum chlorides such as dimethylaluminum chloride and diethylaluminum chloride, organoaluminum halogen compounds such as sesquiethylaluminum chloride and ethylaluminum dichloride, diethylaluminum hydride, diisobutylaluminum hydride and sesquiethylaluminum hydride An organoaluminum hydride compound can also be used.

  Two or more kinds of these organoaluminum compounds can be used in combination.

The amount of the organoaluminum compound used is 0.1 mmol or more per mole of 1,3-butadiene, particularly 0 when cis-1,4 polymerization is carried out using a catalyst system comprising water, an organoaluminum compound and a soluble cobalt compound. It is preferably 5 to 50 mmol. In addition, when cis-1,4 polymerization is performed using a catalyst system composed of an organoaluminum compound, a nickel compound, and a fluorine compound, the amount is 1 × 10 ⁻⁵ to 1 × 10 ⁻¹ mol per mol of 1,3-butadiene. It is preferable.

  Next, a soluble cobalt compound is added to the mixture to which the organoaluminum compound has been added, and 1,3-butadiene is polymerized in a cis-1,4 manner. Soluble cobalt compounds are those that are soluble in an inert organic solvent or liquid 1,3-butadiene based on hydrocarbons or that can be uniformly dispersed, for example, cobalt (II) acetylacetonate and cobalt (III) Cobalt β-diketone complexes such as acetylacetonate, cobalt β-keto acid ester complexes such as cobalt acetoacetate ethyl ester complex, organic compounds having 6 or more carbon atoms such as cobalt octoate, cobalt naphthenate and cobalt benzoate Cobalt halides such as cobalt salts of carboxylic acids, cobalt chloride pyridine complexes and cobalt chloride ethyl alcohol complexes are used. The amount of the soluble cobalt compound used is preferably 0.001 mmol or more, more preferably 0.005 mmol or more, per mol of 1,3-butadiene. Further, the molar ratio (Al / Co) of the organoaluminum compound to the soluble cobalt compound is 10 or more, and particularly preferably 50 or more.

  Further, instead of the soluble cobalt compound, 1,3-butadiene may be polymerized cis-1,4 by adding a nickel compound and a fluorine compound to a mixture to which an organoaluminum compound is added. In this case, water may or may not be added as a component of the cis-1,4 polymerization catalyst.

As the nickel compound, 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 carboxylic acid having 1 to 18 carbon atoms such as nickel octylate, nickel acetate, nickel octoate, Nickel naphthenate, nickel malonate, nickel bisacetylacetonate and trisacetylacetonate, nickel complexes such as ethyl acetoacetate, nickel halide triarylphosphine complex, trialkylphosphine complex, pyridine complex and picoline complex Examples include organic base complexes and various complexes such as ethyl alcohol complexes. The amount of nickel compound used is preferably 1 × 10 ⁻⁷ to 1 × 10 ⁻³ mol per mol of 1,3-butadiene.

As the fluorine compound, boron trifluoride ether, alcohol, or a mixture of these mixtures, or hydrogen fluoride ether, alcohol, or a mixture of these complexes is preferably used. Particularly preferred are boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, hydrogen fluoride diethyl etherate, and hydrogen fluoride dibutyl etherate. The amount of the fluorine compound used is preferably 1 × 10 ⁻⁴ to 1 mol per mol of 1,3-butadiene.

  The temperature for cis-1,4 polymerization of 1,3-butadiene is more than 0 ° C and not more than 100 ° C, preferably 10 to 100 ° C, more preferably 20 to 100 ° C. The polymerization time is preferably in the range of 10 minutes to 2 hours. The cis-1,4 polymerization is preferably performed so that the polymer concentration after the cis-1,4 polymerization is 5 to 26% by weight. The polymerization is carried out by stirring and mixing the solution in a polymerization tank (polymerizer). As a polymerization tank used for the polymerization, a polymerization tank equipped with a high-viscosity liquid stirring apparatus, for example, an apparatus described in JP-B-40-2645 can be used.

  At the time of cis-1,4 polymerization, known molecular weight regulators, for example, non-conjugated dienes such as cyclooctadiene, allene, methylallene (1,2-butadiene), or α-olefins such as ethylene, propylene, and butene-1 Can be used. Moreover, in order to further suppress the production | generation of the gel at the time of superposition | polymerization, a well-known gelation inhibitor can be used.

(Third step)
Next, 1,3-butadiene in the polymerization reaction mixture obtained in the second step is subjected to syndiotactic-1,2. At that time, 1,3-butadiene may or may not be added to the obtained cis-1,4 polymer. Further, when the 1,2 polymerization is carried out, an organoaluminum compound represented by the general formula AlR ₃ (where R is a hydrocarbon group having 1 to 10 carbon atoms), carbon disulfide, and, if necessary, It is preferable to add 1,2-butadiene to 1,2 by adding a soluble cobalt compound, and water may be added to the polymerization system when 1,2-polymerizing.

As the organoaluminum compound represented by the general formula AlR ₃ , trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, triphenylaluminum, and the like are preferable. The organoaluminum compound is preferably 0.1 mmol or more, particularly 0.5 to 50 mmol, per mol of 1,3-butadiene. The concentration of carbon disulfide is 20 mmol / L or less, particularly preferably 0.01 to 10 mmol / L. As an alternative to carbon disulfide, a known phenyl isothiocyanate or xanthate compound may be used. Water is preferably added to the polymerization system after contacting 1,3-butadiene with the organoaluminum compound. The amount of water added is preferably 0.1 to 1.5 mol per mol of the organoaluminum compound. As the soluble cobalt compound, the same compounds as those described in the second step can be used.

  In the production method of the present invention, in the third step, a melting point depressant that lowers the melting point of the resulting 1,2-polybutadiene (b) is added. Examples of the melting point depressant include dimethyl sulfoxide (DMSO), acetone and the like, and dimethyl sulfoxide (DMSO) is particularly preferable from the viewpoint of separation and purification from unreacted 1,3-butadiene.

  The addition amount of the melting point depressant is preferably 0.1 to 10, more preferably 0.3 to 5, and particularly preferably 0.5 to 3 with respect to the organoaluminum compound added in the third step. By adding the above amount of the melting point depressant, the melting point of 1,2-polybutadiene (b) obtained in the third step can be adjusted to 160 to 197 ° C. If the molar ratio of the added amount is more than 10, the melting point is excessively lowered and the die swell tends to deteriorate, and if it is less than 0.1, the effect of improving the fuel efficiency tends to be small.

  The temperature for the 1,2 polymerization is preferably -5 to 100 ° C, particularly preferably -5 to 80 ° C. In the polymerization system for 1,2 polymerization, 1-50 parts by weight, preferably 1-20 parts by weight of 1,3-butadiene per 100 parts by weight of the cis-1,4 polymer obtained in the second step is used. Add. Thereby, the yield of 1,2-polybutadiene (b) at the time of 1,2 polymerization can be increased. The polymerization time is preferably in the range of 2 minutes to 2 hours. The 1,2 polymerization is preferably performed so that the polymer concentration after the 1,2 polymerization is 9 to 29% by weight. The polymerization is carried out by stirring and mixing the polymerization solution in a polymerization tank (polymerizer). As the polymerization tank used for 1,2 polymerization, the viscosity becomes higher during the 1,2 polymerization, and the polymer tends to adhere to the polymerization tank. For example, a polymerization tank equipped with a high-viscosity liquid stirring device, for example, disclosed in JP-B-40-2645. Can be used.

  After the polymerization reaction reaches a predetermined polymerization rate, a known anti-aging agent can be added according to a conventional method. Anti-aging agents include phenol-based 2,6-di-t-butyl-p-cresol (BHT), phosphorus-based trinonylphenyl phosphite (TNP), and sulfur-based 4,6-bis (octylthio). Methyl) -o-cresol and dilauryl-3,3′-thiodipropionate (TPL). These may be used alone or in combination of two or more, and the addition of the antioxidant is 0.001 to 5 parts by weight based on 100 parts by weight of vinyl cis-polybutadiene.

  For the polymerization reaction, a large amount of an alcohol such as methanol and ethanol or a polar solvent such as water is added to the polymerization solution, an inorganic acid such as hydrochloric acid and sulfuric acid, an organic acid such as acetic acid and benzoic acid, or hydrogen chloride gas is polymerized. The reaction is stopped using a method known per se, such as a method of introducing the solution. The resulting vinyl cis-polybutadiene is then separated, washed and subsequently dried according to conventional methods.

<Rubber composition>
The rubber composition of the present invention comprises 10 to 90 parts by weight of the vinyl cis-polybutadiene rubber (A) and 90 to 10 parts by weight of a diene rubber (B) other than (A) (A) + ( B) 10 to 100 parts by weight of the rubber reinforcing agent (C) is blended with 100 parts by weight.

(Diene rubbers other than (A) (B))
In the present invention, the diene rubber other than the component (B) of the component (B) is, for example, at least one diene rubber selected from natural rubber, isoprene rubber, butadiene rubber, emulsion polymerization or solution polymerization styrene-butadiene rubber. Rubber can be used, and it is particularly preferable to use natural rubber and butadiene rubber. When mixing the component (B) with the component (A), it may be mixed at the time of kneading such as a conventional banbury, roll, etc., or a premixed and dried state in the solution state after polymerization is used. May be.

  The ratio of the component (A) to the component (B) is preferably 10 to 90 parts by weight of the component (A) and 90 to 10 parts by weight of the component (B), particularly 10 to 60 parts by weight of the component (A). When the parts by weight and component (B) are 90 to 40 parts by weight, they are optimal as a rubber composition for tires.

(Rubber reinforcement (C))
In the present invention, as the rubber reinforcing agent of component (C), various carbon black, white carbon, activated calcium carbonate, ultrafine magnesium silicate and other inorganic reinforcing agents, syndiotactic-1,2-polybutadiene resin, polyethylene Examples thereof include organic reinforcing agents such as resin, polypropylene resin, high styrene resin, phenol resin, lignin, modified melamine resin, coumarone indene resin, and petroleum resin.
Particularly preferred is carbon black having a particle size of 90 nm or less and a dibutyl phthalate (DBP) oil absorption of 70 ml / 100 g or more, and examples thereof include FEF, FF, GPF, SAF, ISAF, SRF, and HAF.

  (C) As for the mixture ratio of a component, 10-100 weight part is preferable with respect to 100 weight part of rubber components (A) + (B), and 20-60 weight part is more preferable. When the component (C) is less than 20, the tensile stress tends to decrease, and when it exceeds 60, the workability tends to deteriorate.

(Other ingredients)
The rubber composition of the present invention is usually used in the rubber industry as necessary, such as vulcanizing agent, vulcanization aid, anti-aging agent, filler, process oil, zinc white, stearic acid, and the like as other components. You may knead | mix a chemical | medical agent.

  As the vulcanizing agent, known vulcanizing agents such as sulfur, organic peroxides, resin vulcanizing agents, and metal oxides such as magnesium oxide are used.

  As the vulcanization accelerator, known vulcanization accelerators such as aldehydes, ammonia, amines, guanidines, thioureas, thiazoles, thiurams, dithiocarbamates, xanthates and the like are used.

  Examples of the filler include calcium carbonate, basic magnesium carbonate, clay, Lissajous, diatomaceous earth, recycled rubber, and powder rubber.

  Examples of the antiaging agent include amine-ketone, imidazole, amine, phenol, sulfur, and phosphorus.

  The process oil may be any of aromatic, naphthenic, and paraffinic.

  The rubber composition of the present invention can be obtained by kneading the above components using a conventional Banbury, open roll, kneader, biaxial kneader or the like.

  The vulcanized rubber composition obtained by vulcanizing the rubber composition of the present invention is used for tire applications such as studless tires, snow tires and all-season tires, and large tire applications by taking advantage of the improved fuel economy. Is also applicable.

  The rubber composition according to the present invention can be used for each part of a tire such as a sidewall, a cap tread, a base tread, a side reinforcing rubber and a beat filler, and is particularly preferably used for a tire sidewall.

  The tire using the rubber composition according to the present invention is preferably a pneumatic tire, and as a gas to be filled, normal or oxygen partial pressure adjusted air, nitrogen, and inert such as argon and helium There is gas.

  When the rubber composition according to the present invention is used for a sidewall of a tire, the rubber composition according to the present invention containing each component is processed at an unvulcanized stage, and is applied by a normal method on a tire molding machine. A green tire can be obtained by molding. The green tire can be heated and pressurized with a vulcanizer to obtain a tire.

  The rubber composition according to the present invention can be used for anti-vibration rubber, seismic isolation rubber, belt (belt conveyor), rubber crawler, various hoses, Moran, etc., in addition to tire applications.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, these do not limit the objective of this invention. The physical properties of the vinyl cis-polybutadiene rubber (A) and the rubber composition were measured as follows.

<Vinyl cis-polybutadiene rubber (A)>
1. Mooney viscosity (ML _{1 + 4} , 100 ° C)
The Mooney viscosity (ML _{1 + 4} , 100 ° C.) was measured by a Mooney viscometer (SMV-202, manufactured by Shimadzu Corporation) in accordance with JIS K6300, with a preheat 1 minute measurement at 100 ° C. for 4 minutes.

2. Low melting point SPB (1,2-polybutadiene (a)) content The content of low melting point SPB (1,2-polybutadiene (a)) was calculated using the following formula (1).
Content of low melting point SPB (1,2-polybutadiene (a)) = low melting point SPB amount added in the polymerization system ÷ obtained vinyl cis-polybutadiene rubber amount × 100 (1)

3. Graft body content The graft body content was obtained by dissolving 100 mg of the polybutadiene rubber obtained in the second step in 50 mL of tetrahydrofuran, and gel permeation chromatography (HLC-8220 GPC, manufactured by Tosoh Corporation, column: KF-805L × 2). , Detector: RI), and the obtained elution curve was obtained using a commercially available waveform separation software (ORIGIN Pro 8.0), and a peak search and a peak in the vicinity of a molecular weight of 10 ^ 6.10 (or Shoulder) was specified, and the waveform was separated with 500 iterations and an allowable value of 1E-15, and the area ratio of the high molecular weight component was determined.

4). High melting point SPB (1,2-polybutadiene (b)) content (HI)
The infrared spectrum was measured, and the microstructure was calculated from the absorption intensity ratio of cis 740 cm ⁻¹ , trans 967 cm ⁻¹ , vinyl 910 cm ⁻¹ , and 1,2-polybutadiene (a), 1,2-polybutadiene (b), The vinyl 1,2-structure content of the vinyl cis-polybutadiene rubber (A) was calculated.
1,2-polybutadiene (b) (g) was calculated by substituting the calculated vinyl 1,2-structure content and the numerical value obtained from the polymerization conditions and results into the following formula (2).
(1,2-polybutadiene (a) amount (g)) * (vinyl 1,2-structure content of 1,2-polybutadiene (a)) + {(vinyl cis-polybutadiene rubber (A) yield (g) )-(1,2-polybutadiene (a) amount (g)-(1,2-polybutadiene (b) amount (g))} * 0.01+ (1,2-polybutadiene (b) amount (g)) * (Vinyl 1,2-structure content of 1,2-polybutadiene (b)) = (yield of vinyl cis-polybutadiene rubber (A) (g)) * (vinyl 1 of vinyl cis-polybutadiene rubber (A) 1 , 2-structure content) (2)
By substituting the calculated 1,2-polybutadiene (b) amount (g) into the following formula (3), the H.V. I. The amount was calculated.
(HI amount of vinyl cis-polybutadiene rubber (%)) = (1,2-polybutadiene (b) amount (g)) / (yield of vinyl cis-polybutadiene rubber (A) (g) * 100 ... Formula (3)

5. Melting point of high melting point SPB (1,2-polybutadiene (b)) The melting point of high melting point SPB (1,2-polybutadiene (b)) is a value obtained when the sample is about 10 mg and the heating rate is 10 ° C./min. It measured with the scanning calorimeter (the Shimadzu Corporation make, DSC-50).

6). Peak top molecular weight (Mp) of high melting point SPB (1,2-polybutadiene (B))
The peak top molecular weight (Mp) of the high melting point SPB (1,2-polybutadiene (B)) was obtained by dissolving the n-hexane insoluble matter recovered by Soxhlet extraction with orthodichlorobenzene (ODCB) at 145 ° C. and then filtering while hot. The product was subjected to high-temperature GPC measurement (GPC / V2000 type manufactured by Waters) at 145 ° C., and the peak top molecular weight (Mp) of SPB was calculated from a calibration curve obtained using polystyrene as a standard substance.

<Vulcanized product>
1. Low fuel consumption (tan δ)
tan δ was measured using a viscoelasticity measuring apparatus (manufactured by Alpha Technologies, RPA2000) at a temperature of 50 ° C., a frequency of 1 Hz, and a dynamic strain of 3%. Comparative Example 1 was taken as 100, and the reciprocal of tan δ was displayed as an index. Higher values indicate better fuel economy.

(Synthesis Examples 1 to 3)
Low-melting-point SPB (1,2-polybutadiene (a) component: RB830 manufactured by JSR Corporation) and cyclohexane (450 mL) in the amounts shown in Table 1 are put into a 1.5-L stainless steel autoclave that has helical wings and has been replaced with nitrogen. The autoclave was sealed, and then 1,3-butadiene (450 mL) was pumped to prepare 900 ml of a raw material solution (FB). By adding water (H ₂ O) to the raw material solution using a syringe so as to have the concentration shown in Table 1, the autoclave is heated up to 60 ° C. and stirred at 500 rpm for 30 minutes. The melting point SPB was completely dissolved. After the autoclave was cooled to 25 ° C., diethylaluminum chloride and triethylaluminum (molar ratio 3: 1) shown in Table 1 were added using a syringe and stirred for 5 minutes. Next, 1,5-cyclooctadiene (COD) shown in Table 1 was added using a syringe, and the temperature was raised to the temperature shown in Table 1. Cobalt octoate (Co (Oct) ₂ ) shown in Table 1 was added using a syringe, and cis-1,4 polymerization was carried out at the polymerization time and temperature shown in Table 1. To the obtained polymerization reaction mixture, triethylaluminum (TEA) shown in Table 2 was added using a syringe and held for 2 minutes, and then cobalt octoate (Co (Oct) ₂ ) shown in Table 2 was added using a syringe. Hold for another 2 minutes, and further add dimethyl sulfoxide (DMSO) shown in Table 2 using a syringe, and finally add carbon disulfide (CS ₂ ) shown in Table 2 using a syringe. The polymerization was carried out at the polymerization temperature and time described in 1. A polymerization terminator was added to the resulting polymerization reaction mixture to terminate syndiotactic-1,2 polymerization. Thereafter, the autoclave was cooled and depressurized, and the polymerization reaction mixture was taken out into a vat. The entire vat was put into a vacuum dryer warmed to 100 ° C., and unreacted butadiene and solvent were removed to obtain vinyl cis-polybutadiene described in Synthesis Examples 1 to 3. Table 3 shows the physical properties of the obtained vinyl cis-polybutadiene.

(Comparative Synthesis Example 1)
Low-melting-point SPB (1,2-polybutadiene (A) component: RB830 manufactured by JSR Corporation) and cyclohexane (100 mL) in the amounts shown in Table 1 are put into a 1.5 L stainless steel autoclave that has been equipped with helical wings and has been replaced with nitrogen. The autoclave was sealed, and then 500 ml of a mixed solution of 1,3-butadiene and 2-butene (weight ratio 50:50) was pumped to prepare 600 ml of a raw material solution (FB). Water (H ₂ O) and carbon disulfide (CS ₂ ) are added to the raw material solution using a syringe so that the concentrations shown in Table 1 are obtained, and then the autoclave is heated to 60 ° C. for 30 minutes. The low melting point SPB was completely dissolved by stirring at 500 rpm. After the autoclave was cooled to 25 ° C., diethylaluminum chloride and triethylaluminum (molar ratio 3: 1) shown in Table 1 were added using a syringe and stirred for 5 minutes. Next, 1,5-cyclooctadiene (COD) shown in Table 1 was added using a syringe, and the temperature was raised to the temperature shown in Table 1. Cobalt octoate (Co (Oct) ₂ ) shown in Table 1 was added using a syringe, and cis-1,4 polymerization was carried out at the polymerization time and temperature shown in Table 1. To the obtained polymerization reaction mixture, triethylaluminum (TEA) shown in Table 2 was added using a syringe and held for 2 minutes, and then cobalt octoate (Co (Oct) ₂ ) shown in Table 2 was added using a syringe. Then, syndiotactic-1, 2 polymerization was carried out at the polymerization temperature and time described in Table 2. A polymerization terminator was added to the resulting polymerization reaction mixture to terminate syndiotactic-1,2 polymerization. Thereafter, the autoclave was cooled and depressurized, and the polymerization reaction mixture was taken out into a vat. The entire vat was put into a vacuum dryer heated to 100 ° C., and unreacted butadiene and the solvent were removed to obtain vinyl cis-polybutadiene described in Comparative Synthesis Example 1. Table 3 shows the physical properties of the obtained vinyl cis-polybutadiene.

  The vinyl cis-polybutadiene rubbers obtained in Synthesis Examples 1 to 3 and Comparative Synthesis Example 1 are kneaded by adding carbon black, natural rubber, process oil, zinc white, stearic acid and anti-aging agent with a plastmill according to Table 4. A primary blend was performed, followed by a secondary blend in which the vulcanization accelerator and sulfur were added on a roll to create a blend. Further, this blend was molded and press vulcanized at 160 ° C. to obtain a vulcanized product, and then the fuel economy (tan δ) was measured. Table 5 shows the measurement results of physical properties of the vulcanizates.

  From the above, it can be seen that the blends and vulcanizates according to the examples have improved fuel economy compared to the blends and vulcanizates of the comparative examples.

Claims (5)

  1 to 20% by weight of 1,2-polybutadiene (a) having a melting point of 60 to 150 ° C. and 1 to 25% by weight of 1,2-polybutadiene (b) having a melting point of 160 to 197 ° C. Rubber component (A) + comprising 10 to 90 parts by weight of vinyl cis-polybutadiene rubber (A) having a rate of 5 to 25% by weight, and 90 to 10 parts by weight of diene rubber (B) other than (A) + (B) The rubber composition characterized by mix | blending 10-100 weight part of rubber reinforcement agents (C) with respect to 100 weight part. The vinyl cis-polybutadiene rubber (A) is
A first step of preparing a mixture of 1,2-polybutadiene (a) having a melting point of 60 to 150 ° C., 1,3-butadiene and an inert organic solvent mainly containing hydrocarbons;
A catalyst comprising water, an organoaluminum compound and a soluble cobalt compound, or a catalyst comprising an organoaluminum compound, a nickel compound and a fluorine compound is added to the mixture prepared in the first step, and 1,3-butadiene is converted to cis-1. , 4-polymerization second step,
A third step of syndiotactic-1,2 polymerization of 1,3-butadiene in the polymerization reaction mixture obtained in the second step,
The rubber composition according to claim 1, wherein the rubber composition is obtained by a production method of adding a melting point depressant which lowers the melting point of the resulting 1,2-polybutadiene (b) in the third step.   The rubber composition according to claim 1 or 2, wherein the melting point depressant is dimethyl sulfoxide.   A tire using the rubber composition according to claim 1. A tire comprising the rubber composition according to claim 1 as a sidewall.