JP6754575B2 - Rubber composition and tires - Google Patents

Description

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

Conventionally, vinyl cis-polybutadiene rubber has been produced by converting 1,3-butadiene into cis-1,3-butadiene in an inert organic solvent containing hydrocarbons such as benzene, toluene and xylene as main components using a predetermined catalyst. It is carried out by a method of 4-polymerization, followed by syndiotactic-1 and 2 polymerization (hereinafter, may be simply referred to as "1,2 polymerization").

Further, it is desired that the vinyl cis-polybutadiene rubber has various properties improved depending on the use when it is made into a rubber composition. For example, Patent Document 1 states that when 1,3-butadiene is polymerized as cis-1,4, melted 1,2-polybutadiene is mixed in advance to obtain an extrusion processability when a rubber composition is obtained. And vinyl cis-polybutadiene rubber with improved tensile stress is described. Further, Patent Documents 2 to 4 describe vinyl cis-polybutadiene rubber which is further improved and has excellent heat generation property and stretch fatigue resistance.

Japanese Unexamined Patent Publication No. 2008-163144 JP 2012-207052 Japanese Unexamined Patent Publication No. 2012-214735 Japanese Unexamined Patent Publication No. 2012-214765

However, even in the vinyl cis-polybutadiene rubbers described in Patent Documents 1 to 4, which are various improved vinyl cis-polybutadiene rubbers, other rubber compositions for tires, such as low fuel consumption, are obtained. There is still room for improvement in terms of physical properties.

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

As a result of diligent studies in order to achieve the above object, the present inventors have added 1,2-polybutadiene having a specific melting point to the vinyl cis-polybutadiene rubber blended in the rubber composition, and grafted the rubber. We 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, in the present invention, 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. It is composed of 10 to 90 parts by weight of vinyl cis-polybutadiene rubber (A) and 90 to 10 parts by weight of diene rubber (B) other than (A), which is contained and has a grafted body content of 5 to 25% by weight. The present invention relates to a rubber composition characterized by blending 10 to 100 parts by weight of a rubber reinforcing agent (C) with respect to 100 parts by weight of a rubber component (A) + (B), and a tire using the same.

As described above, according to the present invention, it is possible to provide a rubber composition having excellent 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. It contains 1 to 25% by weight of 1,2-polybutadiene (b) having a melting point of 160 to 197 ° C., and has a grafted body content of 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 95 to 99 ° C. Is even more preferable. 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). .. If the content is more than 20% by weight, the fuel efficiency is deteriorated, and if it is less than 1% by weight, the crack resistance is deteriorated, which is not preferable.

The 1,2-polybutadiene (a) is produced by adding or synthesizing the 1,2-polybutadiene (a) in an inert organic solvent in the first step of the method for producing the vinyl cis-polybutadiene rubber (A) described later. The above content can be contained in the polybutadiene rubber (A). It should be noted that, for example, when 1,2-polybutadiene (a) is added or synthesized in the third step, a graft body is not formed and the crack resistance is deteriorated, 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, preferably 175 to 190 ° C. Is even more preferable. If the melting point of 1,2-polybutadiene (b) is lower than 160 ° C, the die swell deteriorates, which is not preferable, and if it is higher than 197 ° C, the fuel efficiency deteriorates, which is not preferable.

The content of 1,2-polybutadiene (b) is 1 to 25% by weight, preferably 5 to 20% by weight, more preferably 10 to 15% by weight, based on the vinyl cis-polybutadiene rubber (A). .. If the content is more than 25% by weight, fuel efficiency is deteriorated, which is not preferable, and if it is less than 1% by weight, 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 5,000 to 300,000, more preferably 20,000 to 150,000. When the peak top molecular weight (Mp) is larger than 300,000, the Mooney viscosity of the formulation tends to be high and the processability tends to deteriorate, and when it is less than 5,000, the die swell tends to deteriorate. In the present invention, the peak top molecular weight (Mp) is the peak top molecular weight in the elution curve obtained by gel permeation chromatography (GPC) measurement, and can be calculated from the calibration curve obtained using polystyrene as a standard substance. ..

(Polybutadiene)
In the vinyl cis-polybutadiene rubber (A) used in the present invention, the polybutadiene as a matrix component contains 1,3-butadiene in the second step of the method for producing the vinyl cis-polybutadiene rubber (A) described later. Obtained by 1,4 polymerization. The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of polybutadiene is preferably 20 to 60, 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.

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

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

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

<Manufacturing method of 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 are the main components. The first step of preparing a mixture with an inert organic solvent, and the mixture prepared in the first step comprises a catalyst composed of water, an organic aluminum compound and a soluble cobalt compound, or an organic aluminum compound, a nickel compound and a fluorine compound. The second step of polymerizing 1,3-butadiene with cis-1,4 by adding a catalyst, and the syndiotactic-1 and 2 polymerization of 1,3-butadiene in the polymerization reaction mixture obtained in the second step. A third step is provided, and in the third step, a melting point lowering agent for lowering the melting point of the obtained 1,2-polybutadiene (b) is added.

(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, the general formula AlR ₃ (where R is carbon). From the group consisting of organic aluminum compounds and carbon disulfides represented by (hydrocarbon groups having 1 to 10 atoms) and, if necessary, alcohols, aldehydes, ketones, esters, nitriles, sulfoxides, amides and phosphoric acid esters. It is produced by polymerizing 1,3-butadiene using a catalyst composed of one or more selected compounds. The 1,2 structure content of the 1,2-polybutadiene (a) is preferably 40 to 99%, particularly preferably 50 to 95%. Further, 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, which is not preferable.

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. Group hydrocarbons, alicyclic hydrocarbons such as cyclohexane and cyclopentane, the above olefin compounds and olefin hydrocarbons such as cis-2-butene and trans-2-butene, hydrocarbons such as mineral spirit, solvent naphtha and kerosine Examples thereof include based solvents and halogenated hydrocarbon solvents such as methylene chloride. Further, the 1,3-butadiene monomer itself may be used as the polymerization solvent.

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

In the method for producing 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-based solvent are not used. The mixture with the active organic solvent can be prepared by dissolving 1,2-polybutadiene (a) in the 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. Further, in a mixture of 1,3-butadiene and an inert organic solvent, 1,2-polybutadiene (a) may be synthesized and dissolved using the above-mentioned catalyst system to prepare a mixture.

(Second step)
Next, the concentration of water 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 1 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, which is not preferable. Further, outside the above range, the generation of gel during polymerization cannot be suppressed, which causes the gel to adhere to the polymerization tank or the like, and the continuous polymerization time cannot be further extended, which is not preferable. As a method for adjusting the water concentration, a known method can be applied. A method of adding and dispersing through a porous filter medium (Japanese Patent Laid-Open No. 4-85304) is also effective.

The organoaluminum compound is added to the mixture obtained by adjusting the water concentration as described above. Organoaluminium compounds include trialkylaluminum, dialkylaluminum chloride, dialkylaluminum bromide, alkylaluminum sesquichloride, alkylaluminum sesquibromide, alkylaluminum dichloride and the like.

Among 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 trialkylaluminum include trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, and trioctyl. Aluminum, triphenylaluminum, tri-p-tolylaluminum, and tribenzylaluminum can be mentioned. The alkyl groups in the trialkylaluminum may be the same or different from each other.

In addition to the above-mentioned 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 and the like. It is also possible to use the hydrided organoaluminum compound of.

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 1 mol of 1,3-butadiene, particularly 0 when cis-1,4 polymerization is carried out using a catalyst system composed of water, an organoaluminum compound and a soluble cobalt compound. It is preferably 5 to 50 mmol. In the case of cis-1,4 polymerization 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 1 mol of 1,3-butadiene. Is preferable.

Then, a soluble cobalt compound is added to the mixture to which the organoaluminum compound is added to carry out cis-1,4 polymerization of 1,3-butadiene. As the soluble cobalt compound, it is soluble in an inert organic solvent containing a hydrocarbon as a main component or liquid 1,3-butadiene, or can be uniformly dispersed, for example, cobalt (II) acetylacetonate and cobalt. (III) Organic β-diketone complex of cobalt such as acetylacetonate, β-ketoate complex of cobalt such as cobalt acetate acetate ethyl ester complex, organic such as cobalt octoate, cobalt naphthenate and cobalt benzoate. Cobalt salts of carboxylic acids, cobalt halide complexes such as 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, particularly 0.005 mmol or more, per mole of 1,3-butadiene. 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, a nickel compound and a fluorine compound may be added to the mixture to which the organoaluminum compound is added to carry out cis-1,4 polymerization of 1,3-butadiene. 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 a 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 carboxylates such as nickel octylate, nickel acetate and nickel octate, and nickel carboxylates having 1 to 18 carbon atoms. Nickel complexes such as nickel naphthenate, nickel malonate, bisacetylacetonate and trisacetylacetonate of nickel, ethyl acetate ester, triarylphosphine complex of nickel halide, trialkylphosphine complex, pyridine complex, picolin complex and the like. Examples thereof include organic base complexes and various complexes such as ethyl alcohol complexes. The amount of the nickel compound used is preferably 1 × 10 ^-7 to 1 × 10 ^-3 mol per 1 mol of 1,3-butadiene.

As the fluorine compound, a complex of boron trifluoride ether, alcohol, or a mixture thereof, or a mixture of hydrogen fluoride ether, alcohol, or a mixture thereof 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 1 mol of 1,3-butadiene.

The temperature at which 1,3-butadiene is polymerized with cis-1,4 is more than 0 ° C. and 100 ° C. or lower, preferably 10 to 100 ° C., and more preferably 20 to 100 ° C. The polymerization time is preferably in the range of 10 minutes to 2 hours. It is preferable to carry out the cis-1,4 polymerization so that the polymer concentration after the cis-1,4 polymerization is 5 to 26% by weight. Polymerization is carried out by stirring and mixing the solutions in a polymerization tank (polymerizer). As the polymerization tank used for polymerization, a polymerization tank equipped with a high-viscosity liquid agitator, for example, the apparatus described in Japanese Patent Publication No. 40-2645 can be used.

During cis-1,4 polymerization, known molecular weight modifiers such as non-conjugated diene such as cyclooctadiene, allenes, methylallenes (1,2-butadiene) or α-olefins such as ethylene, propylene, butene-1 Kind can be used. Further, in order to further suppress the formation of gel during polymerization, a known antigelling agent can be used.

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

As the organoaluminum compound represented by the general formula AlR ₃ , trimethylaluminum, triethylaluminum, triisobutylaluminum, trin-hexylaluminum, triphenylaluminum and the like are suitable. The organoaluminum compound is preferably 0.1 mmol or more, particularly 0.5 to 50 mmol, per mole 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, known phenyl isothiocyanate or xanthate compounds 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 one as described in the second step can be used.

The production method of the present invention is characterized in that a melting point lowering agent for lowering the melting point of the obtained 1,2-polybutadiene (b) is added in the third step. Examples of the melting point lowering agent include dimethyl sulfoxide (DMSO) and acetone, and dimethyl sulfoxide (DMSO) is particularly preferable from the viewpoint of separation and purification from unreacted 1,3-butadiene.

The amount of the melting point lowering agent added is preferably 0.1 to 10 in molar ratio, 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 lowering agent, 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 amount added is more than 10, the melting point tends to be excessively lowered and the die swell tends to be deteriorated, and if it is less than 0.1, the effect of improving fuel efficiency tends to be small, which is not preferable.

1, 2, the polymerization temperature is preferably −5 to 100 ° C., particularly preferably −5 to 80 ° C. In the polymerization system for 1,2 polymerization, 1 to 50 parts by weight, preferably 1 to 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 added. 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. It is preferable to carry out 1,2 polymerization so that the polymer concentration after 1,2 polymerization is 9 to 29% by weight. 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 1,2 polymerization and the polymer easily adheres to the polymerization tank. Therefore, it is described in a polymerization tank equipped with a high-viscosity liquid stirrer, for example, Japanese Patent Publication No. 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 phenolic 2,6-di-t-butyl-p-cresol (BHT), phosphorus-based trinonylphenylphosphite (TNP), and sulfur-based 4,6-bis (octylthio). Methyl) -o-cresol and dilauryl-3,3'-thiodipropionate (TPL) and the like. These may be used alone or in combination of two or more, and the addition of the antiaging agent is 0.001 to 5 parts by weight with respect to 100 parts by weight of vinyl cis-polybutadiene.

The polymerization reaction is a method in which a large amount of alcohol such as methanol and ethanol or a polar solvent such as water is added to the polymerization solution, inorganic acids such as hydrochloric acid and sulfuric acid, organic acids such as acetic acid and benzoic acid, or hydrogen chloride gas is polymerized. Stop using a method known per se, such as a method of introduction into a solution. The vinyl cis-polybutadiene produced is then separated, washed and then dried according to conventional methods.

<Rubber composition>
The rubber composition of the present invention comprises a rubber component (A) + (a) consisting of 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). B) Add 10 to 100 parts by weight of the rubber reinforcing agent (C) to 100 parts by weight.

(Diene rubber (B) other than (A))
In the present invention, as the diene-based rubber other than the component (A) of the component (B), at least one type of diene-based rubber selected from, for example, natural rubber, isoprene rubber, butadiene rubber, emulsified polymerization or solution-polymerized styrene-butadiene rubber Rubber can be used, and it is particularly preferable to use natural rubber and butadiene rubber. When the component (B) is mixed with the component (A), it may be mixed during the usual kneading of Banbury, roll, etc., or it may be mixed in advance in the state of the solution after polymerization and dried. You may.

The ratio of the component (A) to the component (B) is preferably 10 to 90 parts by weight for the component (A) and 90 to 10 parts by weight for the component (B), and particularly 10 to 60 parts by weight for the component (A). When the weight portion and the component (B) are 90 to 40 parts by weight, it is most suitable as a rubber composition for a tire.

(Rubber reinforcement (C))
In the present invention, the rubber reinforcing agent of the component (C) includes various inorganic reinforcing agents such as carbon black, white carbon, activated calcium carbonate, ultrafine magnesium silicate, syndiotactic-1,2-polybutadiene resin, and polyethylene. Examples thereof include organic reinforcing agents such as resins, polypropylene resins, high styrene resins, phenol resins, lignins, modified melamine resins, kumaron inden resins and petroleum resins.
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.

The blending ratio of the component (C) is preferably 10 to 100 parts by weight, more preferably 20 to 60 parts by weight, based on 100 parts by weight of the rubber component (A) + (B). If the component (C) is less than 20, the tensile stress tends to decrease, and if it is more than 60, the workability tends to deteriorate.

(Other ingredients)
The rubber composition of the present invention is usually used in the rubber industry, such as other components such as vulcanizing agent, vulcanization aid, antiaging agent, filler, process oil, zinc oxide, and stearic acid, if necessary. The chemical may be kneaded.

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, lisage, diatomaceous earth, recycled rubber and powdered rubber.

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

As the process oil, any of aromatic type, naphthenic type and paraffin type may be used.

The rubber composition of the present invention can be obtained by kneading each of the above components using a commonly used rubbery, open roll, kneader, twin-screw 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 for large tires by taking advantage of its improved fuel efficiency. 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 beet 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 the gas to be filled includes air, nitrogen, and inert gas such as argon and helium whose oxygen partial pressure is adjusted. There is gas and so on.

When the rubber composition according to the present invention is used for a tire sidewall, the rubber composition according to the present invention containing each component is processed at an unvulcanized stage and pasted on a tire molding machine by a usual method. It is molded and a raw tire can be obtained. The raw tire can be obtained by heating and pressurizing with a vulcanizer injection.

Further, 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, morran, etc.

Hereinafter, the present invention will be specifically described based on examples, but these do not limit the object of the present 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. 1. Mooney viscosity (ML _{1 + 4} , 100 ° C)
The Mooney viscosity (ML _{1 + 4} , 100 ° C.) was measured in accordance with JIS K6300 at 100 ° C. for 1 minute of preheating, and the value for 4 minutes was measured with a Mooney viscometer (SMV-202, manufactured by Shimadzu Corporation).

2. 2. Low melting point SPB (1,2-polybutadiene (a)) content The content of the 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)) = amount of low melting point SPB added to the polymerization system / amount of vinyl cis-polybutadiene rubber obtained × 100 ... (1)

3. 3. Graft content The content of the graft is determined by dissolving 100 mg of polybutadiene rubber obtained in the second step in 50 mL of tetrahydrofuran and performing gel permeation chromatography (manufactured by Tosoh Corporation, HLC-8220 GPC, column: KF-805L × 2). , Detector: RI), and the obtained elution curve was measured using a commercially available waveform separation software (ORIGIN Pro8.0), and a peak search was performed to find the peak top and the peak (or peak around 10 ^ 6.10 in molecular weight). Shoulder) was specified, the number of repetitions was 500, and the waveform was separated with 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 , and vinyl 910 cm ^-1 , and 1,2-polybutadiene (a), 1,2-polybutadiene (b), The vinyl 1,2-structure content of each vinyl cis-polybutadiene rubber (A) was calculated.
1,2-Polybutadiene (b) (g) was calculated by substituting the calculated numerical values obtained from each vinyl 1,2-structure content and the polymerization conditions / 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 (g) of vinyl cis-polybutadiene rubber (A)) * (Vinyl 1 of vinyl cis-polybutadiene rubber (A)) , 2-Structural content) ・ ・ ・ Equation (2)
By substituting the calculated amount (g) of 1,2-polybutadiene (b) into the following formula (3), H.I. 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 ... Equation (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 differential value when the sample is about 10 mg and the heating rate is 10 ° C./min. It was measured by a scanning calorimeter (DSC-50, manufactured by Shimadzu Corporation).

6. Peak top molecular weight (Mp) of high melting point SPB (1,2-polybutadiene (B))
For the peak top molecular weight (Mp) of the high melting point SPB (1,2-polybutadiene (B)), the n-hexane insoluble component recovered by Soxhlet extraction was dissolved in orthodichlorobenzene (ODCB) at 145 ° C. and then filtered 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 the calibration line obtained using polystyrene as a standard substance.

<Vulcanized product>
1. 1. Fuel economy (tan δ)
tan δ was measured using a viscoelasticity measuring device (RPA2000 manufactured by Alpha Technologies, Inc.) at a temperature of 50 ° C., a frequency of 1 Hz, and a dynamic strain of 3%. Comparative Example 1 was set to 100, and the reciprocal of tan δ was expressed as an exponential notation. The higher the value, the better the fuel efficiency.

(Synthesis Examples 1 to 3)
Low melting point SPB (1,2-polybutadiene (a) component: JSR RB830) and cyclohexane (450 mL) in the amounts shown in Table 1 were added to a 1.5 L stainless steel autoclave equipped with helical wings and completed nitrogen replacement. The autoclave was sealed and then 1,3-butadiene (450 mL) was pumped to prepare 900 ml of raw material solution (FB). At a concentration shown in Table 1 in a raw material solution, water (H 2 _O) was added via syringe, then the autoclave was heated to 60 ° C., followed by stirring for 30 minutes · 500 rpm, low The melting point SPB was completely dissolved. After cooling the autoclave to 25 ° C., diethylaluminum chloride and triethylaluminum (molar ratio 3: 1) shown in Table 1 were added using a syringe, and the mixture was stirred for 5 minutes. Then, 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 times and temperatures 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, hold for another 2 minutes, 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, and add Table 2 Syndiotactic-1 and 2 polymerizations were carried out at the polymerization temperature and time described in 1. A polymerization inhibitor was added to the obtained polymerization reaction mixture to terminate syndiotactic-1 and 2 polymerization. Then, the autoclave was cooled and depressurized, and the polymerization reaction mixture was taken out into a vat. The vinyl cis-polybutadiene described in Synthesis Examples 1 to 3 was obtained by putting the whole vat into a vacuum dryer warmed to 100 ° C. and removing unreacted butadiene and a solvent. The physical properties of the obtained vinyl cis-polybutadiene are shown in Table 3.

(Comparative Synthesis Example 1)
Low melting point SPB (1,2-polybutadiene (A) component: JSR RB830) and cyclohexane (100 mL) in the amounts shown in Table 1 were added to a 1.5 L stainless steel autoclave equipped with helical wings and completed nitrogen replacement. 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). As a concentration shown in Table 1 in a raw material solution, water (H 2 _O) and carbon disulfide (CS ₂₎ was added using a syringe, then the autoclave was heated to 60 ° C., 30 minutes, The low melting point SPB was completely dissolved by stirring at 500 rpm. After cooling the autoclave to 25 ° C., diethylaluminum chloride and triethylaluminum (molar ratio 3: 1) shown in Table 1 were added using a syringe, and the mixture was stirred for 5 minutes. Then, 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 times and temperatures shown in Table 1. Triethylaluminium (TEA) shown in Table 2 was added to the obtained polymerization reaction mixture 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 and 2 polymerizations were carried out at the polymerization temperatures and times shown in Table 2. A polymerization inhibitor was added to the obtained polymerization reaction mixture to terminate syndiotactic-1 and 2 polymerization. Then, the autoclave was cooled and depressurized, and the polymerization reaction mixture was taken out into a vat. The vinyl cis-polybutadiene described in Comparative Synthesis Example 1 was obtained by putting the whole vat into a vacuum dryer warmed to 100 ° C. and removing unreacted butadiene and a solvent. The physical properties of the obtained vinyl cis-polybutadiene are shown in Table 3.

The vinyl cis-polybutadiene rubbers obtained in Synthesis Examples 1 to 3 and Comparative Synthesis Example 1 are kneaded with a plastomill according to Table 4 by adding carbon black, natural rubber, process oil, zinc oxide, stearic acid and an antiaging agent. The primary formulation was carried out, and then the secondary formulation was carried out by adding a vulcanization accelerator and sulfur on a roll to prepare a formulation. Further, this compound was molded and press-vulcanized at 160 ° C. to obtain a vulcanized product, and then the fuel efficiency (tan δ) was measured. Table 5 shows the measurement results of the physical properties of the vulcanized product.

From the above, it can be seen that the formulations and vulcanized products according to the examples are improved in fuel efficiency as compared with the formulations and vulcanized products of the comparative examples.

Claims (3)

Rubber with respect to 10 to 90 parts by weight of vinyl cis-polybutadiene rubber (A) and 100 parts by weight of rubber component (A) + (B) consisting of 90 to 10 parts by weight of diene rubber (B) other than (A). A rubber composition containing 10 to 100 parts by weight of the reinforcing agent (C).
The vinyl-cis - polybutadiene rubber (A) is polybutadiene cis-1,4 structure content of 90% or more, a melting point of 60 to 150 ° C. 1,2-polybutadiene (a), a melting point of one hundred sixty to one hundred and ninety-seven ° C. 1,2-Polybutadiene (b), and the 1,2-polybutadiene (a) and the polybutadiene having a cis-1,4 structure content of 90% or more are partially bonded to each other. ,
The content of the 1,2-polybutadiene (a) with respect to the vinyl cis-polybutadiene rubber (A) is 1 to 20% by weight, and the 1,2-polybutadiene (b) with respect to the vinyl cis-polybutadiene rubber (A). ) Is 1 to 25% by weight, and the cis-1,4 structure content is 90% or more. The graft with respect to the total amount of the polybutadiene, the 1,2-polybutadiene (a) and the graft body. A rubber composition having a body content of 5 to 25% by weight. A tire using the rubber composition according to claim 1. A tire using the rubber composition according to claim 1 for a sidewall.