JP6423322B2 - Rubber composition and tire - Google Patents

Description

  The present invention relates to a rubber composition containing a rubber component, a filler, and a polymer of farnesene, and a tire using at least a part of the rubber composition.

In order to improve various performances such as tire grip performance and steering stability performance, various rubber compositions have been studied. In recent years, it has also begun to consider incorporating a farnesene polymer into a rubber composition for tires.
For example, Patent Document 1 describes specific branched conjugated dienes such as myrcene and farnesene for the purpose of providing a tire rubber composition that improves the wear resistance and grip performance of a tire and is excellent in workability. A rubber composition comprising a branched conjugated diene copolymer obtained by copolymerizing a compound and a specific conjugated diene compound is disclosed.
Patent Document 2 discloses a specific branched conjugated diene compound such as myrcene and farnesene for the purpose of providing a tire rubber composition having improved wear resistance and grip performance of a tire and excellent workability. A rubber composition comprising a branched conjugated diene copolymer obtained by copolymerizing a specific conjugated diene compound and a specific vinyl compound is disclosed.
Patent Document 3 describes the modification of rubber components, silica, and farnesene for the purpose of providing a rubber composition capable of obtaining a rubber molded product having excellent rolling resistance performance, operational stability, mechanical strength, and wear resistance. A rubber composition comprising a polymer is disclosed.

International Publication No. 2013/115011 International Publication No. 2013/115010 International Publication No. 2015/025762

As described above, Patent Documents 1 to 3 disclose techniques for incorporating a farnesene polymer into a rubber composition for tires. However, Patent Documents 1 to 3 do not discuss a rubber composition that can improve the balance between the wet grip performance of a tire and the low fuel consumption performance and improve the steering stability. The technology for incorporating a farnesene polymer into a rubber composition for tires has just started to be studied, and further studies are required.
The present invention has been made in view of the above circumstances, and can improve the balance between the wet grip performance and the low fuel consumption performance of a tire and improve the steering stability, and the rubber composition. A tire using at least a part thereof is provided.

  As a result of intensive studies, the present inventors have found that a molded product of a rubber composition containing a specific farnesene copolymer has an excellent balance between tire wet grip performance and fuel efficiency, and excellent steering stability. The present invention has been completed.

That is, the present invention relates to [1] and [2] below.
[1] A rubber component (A) composed of at least one of synthetic rubber and natural rubber, a filler (B) and a modified farnesene copolymer (C), and the filler relative to 100 parts by mass of the rubber component (A) A rubber composition containing 20 to 150 parts by mass of (B) and 1 to 20 parts by mass of the modified farnesene copolymer (C) and satisfying the following requirements (i) to (ii).
<Requirements>
(I) The monomer unit constituting the modified farnesene copolymer (C) is 1 to 99% by mass of the unit (1) derived from farnesene and 1 to 1 unit (2) derived from the aromatic vinyl compound. 99% by mass is contained.
(Ii) The glass transition temperature (TgA) of the rubber component (A) determined by differential thermal analysis and the glass transition temperature (TgC) of the modified farnesene copolymer (C) satisfy the following relational expression.
−50 ° C. <(TgA) − (TgC) <30 ° C.
[2] A tire using at least a part of the rubber composition according to [1].

  According to the present invention, there is provided a rubber composition capable of improving the balance between wet grip performance and low fuel consumption performance of a tire and improving steering stability, and a tire using at least a part of the rubber composition. it can.

[Rubber composition]
The rubber composition according to the present embodiment includes a rubber component (A) composed of at least one of synthetic rubber and natural rubber, a filler (B), and a modified farnesene copolymer (C), and the rubber component (A) A rubber composition containing 20 to 150 parts by mass of the filler (B) and 1 to 20 parts by mass of the modified farnesene copolymer (C) with respect to 100 parts by mass and satisfying the following requirements (i) to (ii): It is a thing.
<Requirements>
(I) The monomer unit constituting the modified farnesene copolymer (C) is 1 to 99% by mass of the unit (1) derived from farnesene and 1 to 1 unit (2) derived from the aromatic vinyl compound. 99% by mass is contained.
(Ii) The glass transition temperature (TgA) of the rubber component (A) determined by differential thermal analysis and the glass transition temperature (TgC) of the modified farnesene copolymer (C) satisfy the following relational expression.
−50 ° C. <(TgA) − (TgC) <30 ° C.

<Rubber component (A)>
The rubber component (A) is composed of at least one of synthetic rubber and natural rubber. Examples thereof include styrene butadiene rubber (hereinafter also referred to as “SBR”), butadiene rubber, isoprene rubber, butyl rubber, halogenated butyl rubber, ethylene propylene diene rubber, butadiene acrylonitrile copolymer rubber, chloroprene rubber, natural rubber, and the like. . Among these, SBR, butadiene rubber, isoprene rubber, and natural rubber are more preferable, and SBR and natural rubber are more preferable. These rubbers may be used alone or in combination of two or more.

[Synthetic rubber]
When a synthetic rubber is used as the rubber component (A) in the present embodiment, SBR, butadiene rubber, isoprene rubber, butyl rubber, halogenated butyl rubber, ethylene propylene diene rubber, butadiene acrylonitrile copolymer rubber, chloroprene rubber and the like are preferable. , SBR, isoprene rubber, and butadiene rubber are more preferable, and SBR is more preferable.

(SBR)
As SBR, those commonly used for tire applications can be used. Specifically, those having a styrene content of 0.1 to 70 mol% are preferred, those having 5 to 60 mol% are more preferred, and 5 More preferred is ˜50 mol%. Moreover, the thing whose vinyl content is 0.1-80 mol% is preferable, and the thing of 5-70 mol% is more preferable. In addition, the vinyl content here represents content of the monomer unit which has a vinyl group among the units derived from all the butadienes contained in SBR. Similarly, the vinyl content of the rubber component (A) represents the content of monomer units actually having a vinyl group with respect to the total amount of monomer units that can have a vinyl group depending on the bonding form.
The weight average molecular weight (Mw) of SBR is preferably 100,000 to 2,500,000, more preferably 150,000 to 2,000,000, and 150,000 to 1,500,000. More preferably. When it is in the above range, the processability, the balance between the wet grip performance and the low fuel consumption performance, and the steering stability are excellent.
In addition, Mw in this specification is the value measured by the method as described in the below-mentioned Example.
The glass transition temperature (Tg) obtained by the differential thermal analysis method of SBR used in the present embodiment is preferably in the range of −95 to 0 ° C., and is preferably in the range of −95 to −5 ° C. More preferably, it is in the range of −95 to −10 ° C., more preferably in the range of −95 to −15 ° C., and still more preferably in the range of −95 to −20 ° C. By setting Tg within the above range, it is possible to suppress an increase in viscosity and to facilitate handling.

≪SBR manufacturing method≫
SBR that can be used in the present embodiment is obtained by copolymerizing styrene and butadiene. There is no restriction | limiting in particular about the manufacturing method of SBR, and any of an emulsion polymerization method, a solution polymerization method, a gas phase polymerization method, and a bulk polymerization method can be used, and an emulsion polymerization method and a solution polymerization method are especially preferable.

(I) Emulsion polymerization styrene butadiene rubber (E-SBR)
E-SBR can be produced by an ordinary emulsion polymerization method. For example, a predetermined amount of styrene and butadiene monomers are emulsified and dispersed in the presence of an emulsifier, and emulsion polymerization is performed using a radical polymerization initiator.
As the emulsifier, for example, a long chain fatty acid salt or rosin acid salt having 10 or more carbon atoms is used. Specific examples include potassium salts or sodium salts of fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, oleic acid and stearic acid.
As the dispersant, water is usually used, and it may contain a water-soluble organic solvent such as methanol and ethanol as long as the stability during polymerization is not inhibited.
Examples of the radical polymerization initiator include persulfates such as ammonium persulfate and potassium persulfate, organic peroxides, hydrogen peroxide, and the like.
In order to adjust the molecular weight of the obtained E-SBR, a chain transfer agent can also be used. Examples of the chain transfer agent include mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan; carbon tetrachloride, thioglycolic acid, diterpene, terpinolene, γ-terpinene, α-methylstyrene dimer, and the like.

Although the temperature of emulsion polymerization can be suitably selected according to the kind of radical polymerization initiator to be used, 0-100 degreeC is preferable normally and 0-60 degreeC is more preferable. The polymerization mode may be either continuous polymerization or batch polymerization. The polymerization reaction can be stopped by adding a polymerization terminator.
Examples of the polymerization terminator include amine compounds such as isopropylhydroxylamine, diethylhydroxylamine, and hydroxylamine; quinone compounds such as hydroquinone and benzoquinone, and sodium nitrite.
After termination of the polymerization reaction, an antioxidant may be added as necessary. After the polymerization reaction is stopped, unreacted monomers are removed from the obtained latex as necessary, and then a salt such as sodium chloride, calcium chloride, potassium chloride is used as a coagulant, and nitric acid, sulfuric acid, etc. The polymer can be recovered as crumbs by adding the acid and coagulating the polymer while adjusting the pH of the coagulation system to a predetermined value and then separating the dispersion solvent. E-SBR can be obtained by washing the crumb with water, followed by dehydration and drying with a band dryer or the like. In addition, at the time of coagulation, if necessary, a latex and an extending oil that has been made into an emulsified dispersion may be mixed and recovered as an oil-extended rubber. In addition, when considering content of the rubber composition which concerns on this Embodiment, extension oil is not included in a rubber component (A).
Examples of commercially available E-SBR include oil-extended styrene butadiene rubber “JSR1723” manufactured by JSR Corporation.

(Ii) Solution-polymerized styrene butadiene rubber (S-SBR)
S-SBR can be produced by an ordinary solution polymerization method. For example, an active metal capable of anion polymerization in a solvent is used, and styrene and butadiene are polymerized in the presence of a polar compound as desired.
Examples of the anion-polymerizable active metal include alkali metals such as lithium, sodium and potassium; alkaline earth metals such as beryllium, magnesium, calcium, strontium and barium; lanthanoid rare earth metals such as lanthanum and neodymium . Of these, alkali metals and alkaline earth metals are preferable, and alkali metals are more preferable. Further, among alkali metals, organic alkali metal compounds are more preferably used.
Examples of the solvent include aliphatic hydrocarbons such as n-butane, n-pentane, isopentane, n-hexane, n-heptane and isooctane; alicyclic hydrocarbons such as cyclopentane, cyclohexane and methylcyclopentane; benzene, And aromatic hydrocarbons such as toluene. These solvents are preferably used in a range where the monomer concentration is 1 to 50% by mass.

Examples of the organic alkali metal compound include organic monolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stilbenelithium; dilithiomethane, 1,4-dilithiobutane, 1,4 -Polyfunctional organic lithium compounds such as dilithio-2-ethylcyclohexane and 1,3,5-trilithiobenzene; sodium naphthalene, potassium naphthalene and the like. Among these, an organic lithium compound is preferable, and an organic monolithium compound is more preferable. The amount of the organic alkali metal compound used is appropriately determined depending on the required molecular weight of S-SBR.
The organic alkali metal compound can also be used as an organic alkali metal amide by reacting with a secondary amine such as dibutylamine, dihexylamine, and dibenzylamine.
The polar compound is not particularly limited as long as it is usually used for adjusting the microstructure of the butadiene site and the distribution in the copolymer chain of styrene without deactivating the reaction in anionic polymerization. Examples include ether compounds such as dibutyl ether, tetrahydrofuran and ethylene glycol diethyl ether; tertiary amines such as tetramethylethylenediamine and trimethylamine; alkali metal alkoxides and phosphine compounds.

The temperature of the polymerization reaction is usually in the range of −80 to 150 ° C., preferably 0 to 100 ° C., more preferably 30 to 90 ° C. The polymerization mode may be either batch polymerization or continuous polymerization. In order to improve the random copolymerization of styrene and butadiene, styrene and butadiene are continuously or intermittently supplied into the reaction solution so that the composition ratio of styrene and butadiene in the polymerization system falls within a specific range. Is preferred.
The polymerization reaction can be stopped by adding an alcohol such as methanol or isopropanol as a polymerization terminator. Coupling of tin tetrachloride, tetrachlorosilane, tetramethoxysilane, tetraglycidyl-1,3-bisaminomethylcyclohexane, 2,4-tolylene diisocyanate, etc. that can react with the polymerization active terminal before adding the polymerization terminator An agent, or a polymerization terminal modifier such as 4,4′-bis (diethylamino) benzophenone or N-vinylpyrrolidone may be added. The polymerization solution after termination of the polymerization reaction can recover the target S-SBR by separating the solvent by direct drying, steam stripping or the like. In addition, before removing the solvent, the polymerization solution and the extending oil may be mixed in advance and recovered as an oil-extended rubber.

(Iii) Modified styrene butadiene rubber (modified SBR)
In the present embodiment, modified SBR in which a functional group is introduced into SBR may be used. Examples of the functional group include an amino group, an alkoxysilyl group, a hydroxy group, an epoxy group, and a carboxyl group.
As a method for producing the modified SBR, for example, before adding a polymerization terminator, tin tetrachloride, tetrachlorosilane, dimethyldichlorosilane, dimethyldiethoxysilane, tetramethoxysilane, tetraethoxysilane, which can react with a polymerization active terminal, Coupling agents such as 3-aminopropyltriethoxysilane, tetraglycidyl-1,3-bisaminomethylcyclohexane, 2,4-tolylene diisocyanate, 4,4′-bis (diethylamino) benzophenone, N-vinylpyrrolidone, etc. And a method of adding other modifiers described in JP-A-2011-132298.
In this modified SBR, the position of the polymer into which the functional group is introduced may be the polymerization terminal or the side chain of the polymer chain.

(Isoprene rubber)
Examples of the isoprene rubber include Ziegler catalysts such as titanium tetrahalide-trialkylaluminum, diethylaluminum chloride-cobalt, trialkylaluminum-boron trifluoride-nickel, and diethylaluminum chloride-nickel; -Commercially available isoprene rubber polymerized using a lanthanoid rare earth metal catalyst such as an organic acid neodymium-Lewis acid or the like, or an organic alkali metal compound in the same manner as S-SBR can be used. Isoprene rubber polymerized with a Ziegler catalyst is preferred because of its high cis isomer content. Further, isoprene rubber having an ultra-high cis body content obtained using a lanthanoid rare earth metal catalyst may be used.

The vinyl content of the isoprene rubber is preferably 50 mol% or less, more preferably 40 mol% or less, and still more preferably 30 mol% or less. When the vinyl content exceeds 50 mol%, the rolling resistance performance (low fuel consumption performance) tends to deteriorate. The lower limit of the vinyl content is not particularly limited. The glass transition temperature varies depending on the vinyl content, but is preferably −20 ° C. or lower, and more preferably −30 ° C. or lower.
The weight average molecular weight (Mw) of the isoprene rubber is preferably 90,000 to 2,000,000, and more preferably 150,000 to 1,500,000. When Mw is in the above range, the workability, the balance between the wet grip performance and the low fuel consumption performance, and the steering stability are excellent.
The isoprene rubber is partly composed of a polyfunctional modifier such as tin tetrachloride, silicon tetrachloride, an alkoxysilane having an epoxy group in the molecule, or an amino group-containing alkoxysilane. You may have the formed branched structure or polar functional group.

(Butadiene rubber)
Examples of the butadiene rubber include Ziegler catalysts such as titanium tetrahalide-trialkylaluminum, diethylaluminum chloride-cobalt, trialkylaluminum-boron trifluoride-nickel, and diethylaluminum chloride-nickel; -Commercially available butadiene rubber polymerized using a lanthanoid rare earth metal catalyst such as organic acid neodymium-Lewis acid or the like, or an organic alkali metal compound in the same manner as S-SBR can be used. Butadiene rubber polymerized with a Ziegler catalyst is preferred because of its high cis isomer content. Moreover, you may use the butadiene rubber of the ultra high cis body content obtained using a lanthanoid type rare earth metal catalyst.
The vinyl content of the butadiene rubber is preferably 50 mol% or less, more preferably 40 mol% or less, and still more preferably 30 mol% or less. When the vinyl content exceeds 50 mol%, the rolling resistance performance (low fuel consumption performance) tends to deteriorate. The lower limit of the vinyl content is not particularly limited. The glass transition temperature varies depending on the vinyl content, but is preferably −40 ° C. or lower, and more preferably −50 ° C. or lower.
The weight average molecular weight (Mw) of the butadiene rubber is preferably 90,000 to 2,000,000, and more preferably 150,000 to 1,500,000. When Mw is in the above range, the workability, the balance between the wet grip performance and the low fuel consumption performance, and the steering stability are excellent.
A part of the butadiene rubber is a polyfunctional type modifier such as tin tetrachloride, silicon tetrachloride, an alkoxysilane having an epoxy group in the molecule, or an amino group-containing alkoxysilane. You may have the formed branched structure or polar functional group.

Along with at least one of SBR, isoprene rubber, and butadiene rubber, one or more of butyl rubber, halogenated butyl rubber, ethylene propylene diene rubber, butadiene acrylonitrile copolymer rubber, chloroprene rubber and the like can be used. Moreover, these manufacturing methods are not specifically limited, What is marketed can be used.
In this embodiment, SBR, isoprene rubber, butadiene rubber and other synthetic rubbers are used in combination with filler (B) and modified farnesene copolymer (C), which will be described later, to achieve a balance between wet grip performance and low fuel consumption performance. , And handling stability can be improved.
When two or more kinds of synthetic rubbers are used in combination, the combination can be arbitrarily selected within a range not impairing the effects of the present embodiment, and by the combination, wet grip performance, low fuel consumption performance, driving stability, etc. Can be adjusted.

[Natural rubber]
Examples of the natural rubber used in the rubber component (A) include TSR such as SMR, SIR, and STR, natural rubber generally used in the tire industry such as RSS, high-purity natural rubber, epoxidized natural rubber, and hydroxylation. Examples thereof include modified natural rubber such as natural rubber, hydrogenated natural rubber, and grafted natural rubber. Among these, SMR20, STR20, and RSS # 3 are preferable from the viewpoint of little variation in quality and easy availability. These may be used alone or in combination of two or more.
In the present embodiment, the balance between wet grip performance and low fuel consumption performance and steering stability can be improved by using natural rubber, filler (B) described later, and modified farnesene copolymer (C) in combination.
The synthetic rubber and natural rubber may be used in combination.
In addition, there is no restriction | limiting in particular in the manufacturing method of the natural rubber used for a rubber component (A), You may use a commercially available thing.

  In this Embodiment, 20-99.9 mass% is preferable, as for content of the rubber component (A) in a rubber composition, 25-80 mass% is more preferable, and 30-70 mass% is still more preferable.

<Filler (B)>
Various fillers are used as the filler (B), and at least one of silica and carbon black is preferable from the viewpoint of obtaining a tire having a balance between wet grip performance and low fuel consumption performance and excellent driving stability. Is more preferable.

〔silica〕
Examples of silica include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, and the like. Among these, wet silica is preferable from the viewpoint of further improving the balance between wet grip performance and low fuel consumption performance and steering stability. These may be used alone or in combination of two or more.
The average particle diameter of silica is preferably 0.5 to 200 nm, more preferably 5 to 150 nm, from the viewpoint of improving the processability of the rubber composition obtained, the balance between wet grip performance and fuel efficiency, and driving stability. Preferably, 10 to 100 nm is more preferable.
The average particle diameter of silica can be determined by measuring the diameter of the particles with a transmission electron microscope and calculating the average value.

〔Carbon black〕
As the carbon black, for example, carbon black such as furnace black, channel black, thermal black, acetylene black, and ketjen black can be used. Among these, furnace black is preferable from the viewpoint of the balance between the vulcanization speed wet grip performance and the low fuel consumption performance and the improvement of the handling stability.
The average particle size of the carbon black is preferably 5 to 100 nm, more preferably 5 to 80 nm, and still more preferably 5 to 70 nm, from the viewpoint of improving the balance between wet grip performance and fuel efficiency and handling stability. .
As carbon black having an average particle diameter of 5 to 100 nm, examples of furnace black commercial products include “Dia Black” manufactured by Mitsubishi Chemical Corporation, “Shiest” manufactured by Tokai Carbon Co., Ltd., and the like. Examples of commercially available acetylene black include “DENKA BLACK” manufactured by Denki Kagaku Kogyo Co., Ltd. Examples of commercially available ketjen black include “ECP600JD” manufactured by Lion Corporation.

From the viewpoint of improving the wettability and dispersibility to the rubber component (A) and the modified polymer (C), the above-described carbon black is subjected to acid treatment with nitric acid, sulfuric acid, hydrochloric acid or a mixed acid thereof, or in the presence of air. Surface oxidation treatment by heat treatment in may be performed. Moreover, you may heat-process at 2,000-3,000 degreeC in presence of a graphitization catalyst from a viewpoint of the mechanical strength improvement of the rubber composition of this Embodiment. As the graphitization catalyst, boron, boron oxide (for example, B ₂ O ₂ , B ₂ O ₃ , B ₄ O ₃ , B ₄ O _5, etc.), boron oxo acid (for example, orthoboric acid, metaboric acid, Tetraboric acid etc.) and salts thereof, boron carbide (eg B ₄ C, B ₆ C etc.), boron nitride (BN) and other boron compounds are preferably used.

The particle size of carbon black can be adjusted by pulverization or the like. For carbon black pulverization, high-speed rotary pulverizer (hammer mill, pin mill, cage mill), various ball mills (rolling mill, vibration mill, planetary mill), stirring mill (bead mill, attritor, distribution pipe mill, annular mill) Etc. can be used.
The average particle size of carbon black can be determined by measuring the particle diameter with a transmission electron microscope and calculating the average value.

[Other fillers]
The rubber composition of the present embodiment further contains a filler other than silica and carbon black as necessary for the purpose of improving mechanical strength, adjusting the hardness, improving economy by blending an extender, and the like. May be.

The filler other than silica and carbon black is appropriately selected according to the application, for example, organic filler, clay, talc, mica, calcium carbonate, magnesium hydroxide, aluminum hydroxide, barium sulfate, titanium oxide, One or more inorganic fillers such as glass fiber, fibrous filler, and glass balloon can be used.
The content of the filler (B) is 20 to 150 parts by mass with respect to 100 parts by mass of the rubber component (A) from the viewpoint of improving the balance between wet grip performance and low fuel consumption performance and driving stability. -130 mass parts is preferable, and 20-120 mass parts is more preferable.
Moreover, when using silica as a filler (B), content of a silica is 20-150 mass parts with respect to 100 mass parts of rubber components (A) from the same viewpoint, and 20-130 mass parts is preferable, 20-120 mass parts is more preferable.

<Modified farnesene copolymer (C)>
In the modified farnesene copolymer (C) of the present embodiment, the monomer unit constituting the modified farnesene copolymer (C) is 1 to 99% by mass of the unit (1) derived from farnesene, aromatic vinyl. 1 to 99% by mass of the unit (2) derived from the compound is contained.
Here, the monomer unit constituting the modified farnesene copolymer (C) does not include a modified group (functional group).
This modified farnesene copolymer (C) can be suitably produced by introducing a functional group into an unmodified farnesene copolymer (hereinafter also referred to as “unmodified copolymer”).

[Unmodified copolymer]
The unmodified copolymer contains 1 to 99% by mass of the unit (1) derived from farnesene and 1 to 99% by mass of the unit (2) derived from the aromatic vinyl compound.

(Unit derived from farnesene (1))
As the unit (1) derived from farnesene, at least one of α-farnesene and β-farnesene represented by the formula (I) can be used. From the viewpoint of ease of production of the modified polymer, the rolling resistance performance is improved. From the viewpoint, it is preferable to include a monomer unit derived from β-farnesene.

  The content of the unit (1) derived from farnesene in the unmodified copolymer is 1 to 99% by mass. If the content is less than 1% by mass, the effect derived from farnesene that lowers the melt viscosity and improves processability cannot be sufficiently obtained. Moreover, when it exceeds 99 mass%, abrasion resistance will fall. From this viewpoint, the content of the unit (1) derived from farnesene in the unmodified copolymer is preferably 1 to 98% by mass, more preferably 1 to 90% by mass, and still more preferably 1 to 80% by mass. It is.

(Unit derived from aromatic vinyl compound (2))
Examples of the aromatic vinyl compound include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-t-butylstyrene, 4-cyclohexylstyrene, 4- Dodecylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 2,4,6-trimethylstyrene, 2-ethyl-4-benzylstyrene, 4- (phenylbutyl) styrene, 1-vinylnaphthalene, 2- Aromatic vinyl compounds such as vinylnaphthalene, vinylanthracene, N, N-diethyl-4-aminoethylstyrene, vinylpyridine, 4-methoxystyrene, monochlorostyrene, dichlorostyrene, divinylbenzene, and the like can be given. Among these, styrene, α-methylstyrene, and 4-methylstyrene are preferable.

  The content of the unit (2) derived from the aromatic vinyl compound in the unmodified copolymer is from 1 to 99% by mass from the viewpoints of wet grip performance and low fuel consumption performance (rolling resistance performance). That is, when it is 1% by mass or more, wet grip performance is improved. Further, when it is 99% by mass or less, low fuel consumption performance (rolling resistance performance) is improved. From this viewpoint, the content of the unit (2) derived from the aromatic vinyl compound in the unmodified copolymer is preferably 1 to 98% by mass, more preferably 1 to 80% by mass, and still more preferably 1 to 70% by mass.

(Units derived from conjugated dienes other than farnesene (3))
The modified farnesene copolymer (C) may contain units other than the unit (1) derived from the farnesene and the unit (2) derived from the aromatic vinyl compound.
When units other than these units (1) and units (2) are included, the unit is preferably a unit (3) derived from a conjugated diene other than farnesene. When the unit (3) derived from a conjugated diene other than farnesene is included, fuel efficiency tends to be improved.
Examples of the unit (3) derived from conjugated dienes other than farnesene include conjugated dienes having 12 or less carbon atoms. Examples of the conjugated diene having 12 or less carbon atoms include butadiene, isoprene, 2,3-dimethyl-butadiene, 2-phenyl-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3- Examples include hexadiene, 1,3-octadiene, 1,3-cyclohexadiene, 2-methyl-1,3-octadiene, 1,3,7-octatriene, myrcene, chloroprene and the like. Of these, butadiene, isoprene, and myrcene are more preferable. These conjugated dienes may be used alone or in combination of two or more.

The content of the unit (3) derived from the conjugated diene other than farnesene in the unmodified copolymer is preferably 0 to 99% by mass, more preferably 0 to 90% by mass, and still more preferably 0 to 80% by mass. It is. It is also a preferred embodiment that the unmodified copolymer does not contain the unit (3).
In addition, when the unit (3) derived from conjugated dienes other than farnesene is included, the content thereof is preferably 1 to 99% by mass, more preferably 1 to 98% by mass, and still more preferably 1 to 90% by mass, and more. Still more preferably, it is 5-80 mass%.

In the present specification, the vinyl content of the unmodified copolymer or the modified farnesene copolymer (C) is a single amount having a vinyl group among the units (3) derived from conjugated diene compounds other than all farnesene. It is content of a body unit, and can be measured by a method using ¹ H-NMR described in Examples described later.

  In the unmodified copolymer, the total content of units derived from farnesene (1), units derived from aromatic vinyl compounds (2), and units derived from conjugated dienes other than farnesene (3) is preferably It is 80 mass% or more, More preferably, it is 90 mass% or more, More preferably, it is 95 mass% or more, More preferably, it is 99 mass% or more.

The glass transition temperature of the unmodified copolymer varies depending on the vinyl content, farnesene, and the content of monomers other than farnesene as required, but is preferably −90 to 10 ° C., preferably −90 to 0 ° C. Is more preferable, and −90 to −5 ° C. is still more preferable. When it is in the above range, the rolling resistance performance is good. Moreover, it can suppress that a viscosity becomes high and can handle it easily.
The vinyl content of the unmodified copolymer is preferably 99 mol% or less, more preferably 90 mol% or less.
In the unmodified copolymer, the glass transition temperature (TgA) of the rubber component (A) obtained by differential thermal analysis and the glass transition temperature (TgC ′) of the unmodified copolymer satisfy the following relational expression. It is preferable.
−40 ° C. <(TgA) − (TgC ′) <40 ° C.
When “(TgA) − (TgC ′)” is within the above range, the balance between the wet grip performance and the low fuel consumption performance and the steering stability are improved. From this viewpoint, “(TgA)-(TgC ′)” is preferably −40 to 40 ° C., more preferably −35 to 40 ° C., and still more preferably −30 to 40 ° C.

[Production method of unmodified copolymer]
The unmodified copolymer can be produced by an emulsion polymerization method, a method described in International Publication No. 2010/027463, International Publication No. 2010/027464, or the like. Among these, an emulsion polymerization method or a solution polymerization method is preferable, and a solution polymerization method is more preferable.

(Emulsion polymerization method)
As an emulsion polymerization method for obtaining an unmodified copolymer, a known method can be applied. For example, a predetermined amount of farnesene monomer is emulsified and dispersed in the presence of an emulsifier, and emulsion polymerization is performed using a radical polymerization initiator.
As the emulsifier, for example, a long chain fatty acid salt or rosin acid salt having 10 or more carbon atoms is used. Specific examples include potassium salts or sodium salts of fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, oleic acid and stearic acid.
As the dispersant, water is usually used, and it may contain a water-soluble organic solvent such as methanol and ethanol as long as the stability during polymerization is not inhibited.
Examples of the radical polymerization initiator include persulfates such as ammonium persulfate and potassium persulfate, organic peroxides, and hydrogen peroxide.
In order to adjust the molecular weight of the resulting unmodified copolymer, a chain transfer agent can also be used. Examples of the chain transfer agent include mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan; carbon tetrachloride, thioglycolic acid, diterpene, terpinolene, γ-terpinene, α-methylstyrene dimer, and the like.
The emulsion polymerization temperature can be appropriately selected depending on the type of the radical polymerization initiator to be used. The polymerization mode may be either continuous polymerization or batch polymerization. The polymerization reaction can be stopped by adding a polymerization terminator.
Examples of the polymerization terminator include amine compounds such as isopropylhydroxylamine, diethylhydroxylamine, and hydroxylamine, quinone compounds such as hydroquinone and benzoquinone, and sodium nitrite.
After termination of the polymerization reaction, an antioxidant may be added as necessary. After the polymerization reaction is stopped, unreacted monomers are removed from the obtained latex as necessary, and then a salt such as sodium chloride, calcium chloride, potassium chloride is used as a coagulant, and nitric acid, sulfuric acid, etc. The unmodified copolymer is coagulated while adjusting the pH of the coagulation system to a predetermined value by adding an acid, and then the unmodified copolymer is recovered by separating the dispersion solvent. Next, after washing with water and dehydration, drying is performed to obtain an unmodified copolymer. In the course of coagulation, if necessary, latex and an extending oil that has been made into an emulsified dispersion may be mixed and recovered as an oil-modified unmodified copolymer.

(Solution polymerization method)
As a solution polymerization method for obtaining an unmodified copolymer, a known method can be applied. For example, a farnesene monomer is polymerized in a solvent using a Ziegler catalyst, a metallocene catalyst, and an anion-polymerizable active metal, if desired, in the presence of a polar compound.
Examples of the anion-polymerizable active metal include alkali metals such as lithium, sodium and potassium; alkaline earth metals such as beryllium, magnesium, calcium, strontium and barium; lanthanoid rare earth metals such as lanthanum and neodymium .
Of these, alkali metals and alkaline earth metals are preferable, and alkali metals are more preferable. Further, among alkali metals, organic alkali metal compounds are more preferably used.
Examples of the solvent include aliphatic hydrocarbons such as n-butane, n-pentane, isopentane, n-hexane, n-heptane and isooctane; alicyclic hydrocarbons such as cyclopentane, cyclohexane and methylcyclopentane; benzene, Aromatic hydrocarbons such as toluene and xylene are exemplified.
Examples of the organic alkali metal compound include organic monolithium compounds such as methyllithium, ethyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, hexyllithium, phenyllithium, stilbenelithium; dilithiomethane, dilithionaphthalene Polyfunctional organolithium compounds such as 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene; sodium naphthalene, potassium naphthalene and the like. Among these, an organic lithium compound is preferable, and an organic monolithium compound is more preferable. The amount of the organic alkali metal compound used is appropriately determined depending on the required molecular weight of the farnesene copolymer, but is preferably 0.01 to 50 parts by mass with respect to 100 parts by mass of farnesene.
The organic alkali metal compound can also be used as an organic alkali metal amide by reacting with a secondary amine such as dibutylamine, dihexylamine, and dibenzylamine.
The polar compound is used to adjust the microstructure of the farnesene moiety in anionic polymerization without deactivating the reaction. For example, ether compounds such as dibutyl ether, tetrahydrofuran, ethylene glycol diethyl ether; tetramethylethylenediamine, trimethylamine, etc. Tertiary amines; alkali metal alkoxides, phosphine compounds and the like. The polar compound is preferably used in an amount of 0.01 to 1,000 molar equivalents relative to the organic alkali metal compound.

The temperature of the polymerization reaction is usually in the range of −80 to 150 ° C., preferably 0 to 100 ° C., more preferably 10 to 90 ° C. The polymerization mode may be either batch polymerization or continuous polymerization.
The polymerization reaction can be stopped by adding an alcohol such as methanol or isopropanol as a polymerization terminator. The unmodified copolymer can be isolated by pouring the obtained polymerization reaction solution into a poor solvent such as methanol to precipitate the unmodified copolymer, or washing the polymerization reaction solution with water, separating, and drying. .

[Modification method of unmodified copolymer]
The modified farnesene copolymer (C) is added to the unmodified copolymer with a modifier such as tetraethoxysilane, carbon dioxide, or ethylene oxide that can react with the polymerization active terminal before adding a polymerization terminator. After the addition of a polymerization terminator, the method can be obtained by a modification method such as a method (II) of grafting a modifier such as maleic anhydride onto an unmodified copolymer.

Examples of the functional group introduced into the unmodified copolymer include an amino group, an ammonium group, an amide group, an imino group, an imidazole group, a urea group, an alkoxysilyl group, a silanol group, a hydroxy group, an epoxy group, and an ether group. , Carboxy group, carbonyl group, carboxylic acid ester group, sulfonic acid group, sulfonic acid ester group, phosphoric acid group, phosphoric ester group, mercapto group, isocyanate group, nitrile group, silicon halide group, tin halide group, pyridine Examples thereof include a cyclic group and a functional group derived from an acid anhydride. Among these, one or more selected from a carboxy group, an amino group, a hydroxy group, an alkoxysilyl group, an epoxy group, a pyridine ring group, and a functional group derived from an acid anhydride are preferable, and a function derived from an acid anhydride is preferable. As the group, a functional group derived from maleic anhydride is more preferable.
In addition, about the position where a functional group is introduced in the modified farnesene copolymer (C), it may be a polymerization terminal or a side chain of a polymer chain, but a plurality of functional groups can be easily introduced. From the viewpoint of being capable of being made, it is preferably a side chain of a polymer chain. Moreover, the said functional group may be contained individually by 1 type, and may be contained 2 or more types. Therefore, the modified farnesene copolymer (C) may be modified with one modified compound, or may be modified with two or more modified compounds.

Examples of the modifier that can be used in the method (I) include dimethyldiethoxysilane, tetramethoxysilane, tetraethoxysilane, 3-aminopropyltriethoxysilane, tetraglycidyl-1,3-bisaminomethylcyclohexane. 2,4-tolylene diisocyanate, carbon dioxide, ethylene oxide, succinic anhydride, 4,4′-bis (diethylamino) benzophenone, N-vinylpyrrolidone, N-methylpyrrolidone, vinylpyridine, 4-dimethylaminobenzylideneaniline, Examples include denaturing agents such as dimethylimidazolidinone, and other denaturing agents described in JP2011-132298A.
The modifying agent is preferably in the range of 0.01 to 100 molar equivalents relative to the organic alkali metal compound.
The reaction temperature is usually in the range of -80 to 150 ° C, preferably 0 to 100 ° C, more preferably 10 to 90 ° C.
Also, before adding a polymerization terminator, the above modifier is added to introduce a functional group into the unmodified copolymer, and then a modifier capable of reacting with the functional group is added to co-polymerize another functional group. It may be introduced into the coalescence.

  Examples of the modifier that can be used in the method (II) include unsaturated carboxylic acid anhydrides such as maleic anhydride, citraconic anhydride, 2,3-dimethylmaleic anhydride and itaconic anhydride; maleic acid and fumaric acid Unsaturated carboxylic acids such as citraconic acid and itaconic acid; unsaturated carboxylic acid esters such as maleic acid ester, fumaric acid ester, citraconic acid ester and itaconic acid ester; maleic acid amide, fumaric acid amide, citraconic acid amide and itaconic acid Unsaturated carboxylic acid amides such as amides; Unsaturated carboxylic acid imides such as maleic imides, fumaric imides, citraconic imides, itaconic imides; maleimides, bis [3- (triethoxysilyl) propyl] tetrasulfide, bis [ 3- (Triethoxysilyl) propyl] disulfide (3-mercaptopropyl) trimethoxysilane, (3-mercaptopropyl) triethoxysilane, triethoxymethylsilane, hydroxyacetic acid, (3-aminopropyl) triethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxy Silane etc. are mentioned.

  In the method (II), the method for grafting the modifying agent to the unmodified copolymer is not particularly limited. For example, by adding the unmodified copolymer, the modifying agent, and a radical catalyst as necessary, A method of heating in the presence or absence of an organic solvent can be employed. Examples of the organic solvent used in the above method generally include hydrocarbon solvents and halogenated hydrocarbon solvents. Among these organic solvents, hydrocarbon solvents such as n-butane, n-hexane, n-heptane, cyclohexane, benzene, toluene and xylene are preferable.

In the modification methods such as the method (I) and the method (II), the modifying agent is preferably 0.1 to 100 parts by mass, more preferably 0.1 to 90 parts by mass with respect to 100 parts by mass of the unmodified copolymer. Parts, more preferably 0.5 to 70 parts by mass, and still more preferably 0.5 to 50 parts by mass. When the amount of the functional group added in the modified farnesene copolymer (C) is within this range, the fuel efficiency is improved, and the steering stability is improved due to the increase in the elastic modulus. The amount of the functional group added to the modified farnesene copolymer (C) can be calculated based on the reaction rate of the modifier, or can be determined by the method described in the examples described later.
The reaction temperature is usually preferably in the range of 0 to 200 ° C, more preferably in the range of 50 to 200 ° C. Moreover, when performing reaction which introduce | transduces a modifier | denaturant, you may add an anti-aging agent from a viewpoint etc. which suppress a side reaction.
Further, after grafting a modifying agent to the unmodified copolymer and introducing a functional group, a modifying agent capable of reacting with the functional group may be added to introduce another functional group into the polymer. Specifically, after grafting a carboxylic anhydride to an unmodified polymer obtained by living anion polymerization, a method of reacting a compound such as 2-hydroxyethyl methacrylate, methanol, water, ammonia, amine, etc. Can be mentioned.

By reacting these compounds, the carboxylic anhydride portion in the modified farnesene copolymer (C) undergoes a ring-opening reaction, and has a functional group such as a dicarboxylic acid group, a dicarboxylic acid monoester group, or a dicarboxylic acid monoamide group. A farnesene copolymer (C) can be obtained.
In the case of producing a modified farnesene copolymer (C) that has undergone a ring-opening reaction of the carboxylic anhydride moiety in the modified farnesene copolymer (C) to produce a secondary modified, the amount of the compound used in the ring-opening reaction is 0.5-5 molar equivalent is preferable with respect to the carboxylic anhydride group in a coalescence, and 0.8-5 molar equivalent is more preferable. By performing the above modification, the elastic modulus is increased and the steering stability is improved.

  The reaction rate of the modifier with respect to the modified farnesene copolymer (C) is preferably 40 to 100%, more preferably 60 to 100%, and still more preferably 80 to 100%. When the reaction rate of the modifier is within the above range, the balance between the wet grip performance and the low fuel consumption performance and the steering stability are improved. The reaction rate of the modifier can be calculated as a ratio of the amount introduced into the polymer with respect to the total amount of modifier charged during the modification reaction.

[Physical properties of modified farnesene copolymer (C)]
The weight average molecular weight (Mw) of the modified farnesene copolymer (C) is preferably 2,000 to 500,000, more preferably 2,000 to 400,000, still more preferably 2,000 to 300,000, 000 to 200,000 is even more preferable. When the Mw of the modified farnesene copolymer (C) is 2,000 or more, crosslinking with the rubber component (A) is likely to occur, so that the wear resistance is improved. Moreover, the workability of a rubber composition improves that Mw is 500,000 or less.
In the present specification, the Mw of the modified farnesene copolymer (C) is a value determined by the method described in Examples described later.
In the present embodiment, two types of modified farnesene copolymers (C) having different Mw may be used in combination.

  The melt viscosity at 38 ° C. of the modified farnesene copolymer (C) is preferably 0.1 to 3,000 Pa · s, more preferably 0.1 to 2,500 Pa · s, and 0.1 to 2,000 Pa · s. Is more preferable, and 0.1 to 1,500 Pa · s is still more preferable. When the melt viscosity of the modified farnesene copolymer (C) is within the above range, kneading of the resulting rubber composition becomes easy and processability is improved. In the present specification, the melt viscosity of the modified farnesene copolymer (C) is a value determined by the method described in Examples described later.

  The glass transition temperature (TgC) of the modified farnesene copolymer (C) is preferably -90 to 10 ° C, more preferably -90 to 0 ° C, still more preferably -90 to -5 ° C. When it is in the above range, the fuel efficiency is good. Moreover, it can suppress that a viscosity becomes high and can handle it easily.

The modified farnesene copolymer (C) has a glass transition temperature (TgA) of the rubber component (A) obtained by differential thermal analysis and a glass transition temperature (TgC) of the modified farnesene copolymer (C). The following relational expression is satisfied.
−50 ° C. <(TgA) − (TgC) <30 ° C.
When “(TgA) − (TgC)” is within the above range, the balance between the wet grip performance and the low fuel consumption performance and the steering stability are improved. From this viewpoint, “(TgA)-(TgC)” is preferably −45 to 30 ° C., more preferably −40 to 30 ° C., and still more preferably −35 to 30 ° C.

  The vinyl content (degree of vinylation) of the modified farnesene copolymer (C) is preferably from 0 to 90 mol%, more preferably from 0 to 85 mol%, still more preferably from 0 to 80 mol%. When the vinyl content is within the above range, wet grip performance is improved, elastic modulus is improved, steering stability is improved, and fuel efficiency is further improved.

  The functional group amount (modified amount) added to the modified farnesene copolymer (C) is preferably 0.1 to 100 parts by mass, more preferably 0.1 to 100 parts by mass of the unmodified copolymer. -50 mass parts, More preferably, it is 0.5-50 mass parts, More preferably, it is used in 0.5-30 mass parts. When the amount of the functional group added to the modified farnesene copolymer (C) is within this range, the fuel efficiency is improved, and the steering stability is improved due to the increase in the elastic modulus. The amount of the functional group added to the modified farnesene copolymer (C) can be calculated based on the reaction rate of the modifier, or can be determined by the method described in the examples described later.

  In this modified farnesene copolymer (C), the position at which the functional group is introduced is as described above.

  In the present embodiment, the content of the modified farnesene copolymer (C) with respect to 100 parts by mass of the rubber component (A) is 1 to 20 parts by mass, preferably 2 to 15 parts by mass, and 2.5 to 15 Part by mass is more preferable. When the content of the modified farnesene copolymer (C) is within the above range, the mechanical strength and rolling resistance performance are good. In addition, it has excellent wear resistance, and when used in a tire or the like, the deformation of the tire is small, and the steering stability can be improved.

<Vulcanizing agent>
The rubber composition of the present embodiment preferably contains a vulcanizing agent. Examples of the vulcanizing agent include sulfur and sulfur compounds. These may be used alone or in combination of two or more. The content of the vulcanizing agent is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 10 parts by mass, and further 0.8 to 5 parts by mass with respect to 100 parts by mass of the rubber component (A). preferable.

<Vulcanization accelerator>
The rubber composition of the present embodiment may contain a vulcanization accelerator. Examples of the vulcanization accelerator include guanidine compounds, sulfenamide compounds, thiazole compounds, thiuram compounds, thiourea compounds, dithiocarbamic acid compounds, aldehyde-amine compounds or aldehyde-ammonia compounds, imidazoline compounds. Compounds, xanthate compounds, and the like. These may be used alone or in combination of two or more. When it contains the said vulcanization accelerator, 0.1-15 mass parts is preferable with respect to 100 mass parts of rubber components (A), and 0.1-10 mass parts is more preferable.

<Vulcanization aid>
The rubber composition of the present embodiment may contain a vulcanization aid. Examples of the vulcanization aid include fatty acids such as stearic acid, metal oxides such as zinc white, and fatty acid metal salts such as zinc stearate. These may be used alone or in combination of two or more. When the said vulcanization | cure adjuvant is contained, 0.1-15 mass parts is preferable with respect to 100 mass parts of rubber components (A), and 1-10 mass parts is more preferable.

<Silane coupling agent>
The rubber composition of the present embodiment preferably contains a silane coupling agent. Examples of the silane coupling agent include sulfide compounds, mercapto compounds, vinyl compounds, amino compounds, glycidoxy compounds, nitro compounds, and chloro compounds.
Examples of sulfide compounds include bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, and bis (2-trimethoxy). Silylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (3-trimethoxysilylpropyl) Disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N, -Dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, etc. Can be mentioned.
Examples of the mercapto compound include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the like.
Examples of the vinyl compound include vinyl triethoxysilane and vinyl trimethoxysilane.
Examples of amino compounds include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, and 3- (2-aminoethyl) aminopropyltrimethoxy. Silane etc. are mentioned.
Examples of glycidoxy compounds include γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and γ-glycidoxypropylmethyldimethoxysilane. Can be mentioned.
Examples of the nitro compound include 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane.
Examples of the chloro compound include 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, and the like.
These silane coupling agents may be used alone or in combination of two or more. Of these, silane coupling agents containing sulfur such as sulfide compounds and mercapto compounds are preferred from the viewpoint of a large reinforcing effect, and bis (3-triethoxysilylpropyl) disulfide and bis (3-triethoxysilylpropyl) tetra Sulfide and 3-mercaptopropyltrimethoxysilane are more preferable.

  0.1-30 mass parts is preferable, as for content of the said silane coupling agent with respect to 100 mass parts of rubber components (A), 0.5-20 mass parts is more preferable, and 1-15 mass parts is still more preferable. When the content of the silane coupling agent is within the above range, dispersibility, reinforcement, and abrasion resistance are improved.

<Other ingredients>
The rubber composition of the present embodiment is intended to improve processability, fluidity, etc. within a range that does not impair the effects of the invention, and if necessary, silicon oil, aroma oil, TDAE (Treated Distilled Aromatic Extracts), MES (Mild Extracted Solvates), RAE (Residual Aromatic Extracts), paraffin oil, naphthenic oil and other process oils, aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, C9 resins, rosin resins, coumarone / indene resins, It contains a resin component such as a phenolic resin, a low molecular weight polybutadiene, a low molecular weight polyisoprene, a low molecular weight styrene butadiene copolymer, a liquid polymer such as a low molecular weight styrene isoprene copolymer, and an unmodified polymer as a softening agent. Also good. The copolymer may be in any polymerization form such as block or random. The weight average molecular weight (Mw) of the liquid polymer is preferably 500 to 100,000 from the viewpoint of processability. When the rubber composition of the present embodiment contains the above process oil, resin component or liquid polymer, and unmodified polymer as a softening agent, the content thereof is 50 mass with respect to 100 mass parts of the rubber component (A). The amount is preferably less than the part.

The rubber composition of the present embodiment is an anti-aging agent, an antioxidant, a wax, and a lubricant as needed for the purpose of improving weather resistance, heat resistance, oxidation resistance, etc., as long as the effects of the invention are not impaired. , Light stabilizers, scorch prevention agents, processing aids, colorants such as pigments and dyes, flame retardants, antistatic agents, matting agents, antiblocking agents, UV absorbers, mold release agents, foaming agents, antibacterial agents, You may contain 1 type (s) or 2 or more types of additives, such as an antifungal agent and a fragrance | flavor.
Examples of the antioxidant include hindered phenol compounds, phosphorus compounds, lactone compounds, hydroxyl compounds, and the like.
Examples of the antiaging agent include amine-ketone compounds, imidazole compounds, amine compounds, phenolic compounds, sulfur compounds, and phosphorus compounds.

  The rubber composition of the present embodiment can be used after being vulcanized using the above vulcanizing agent and by being crosslinked by adding a crosslinking agent. Examples of the cross-linking agent include oxygen, organic peroxide, phenol resin and amino resin, quinone and quinonedioxime derivatives, halogen compounds, aldehyde compounds, alcohol compounds, epoxy compounds, metal halides and organometallic halides, and silane compounds. Etc. These may be used alone or in combination of two or more. As for content of a crosslinking agent, 0.1-10 mass parts is preferable with respect to 100 mass parts of rubber components (A).

  The method for producing the rubber composition according to the present embodiment is not particularly limited, and the above components may be mixed uniformly. Examples of the uniform mixing method include, for example, a tangential or meshing type closed kneader such as a kneader ruder, brabender, banbury mixer, internal mixer, single screw extruder, twin screw extruder, mixing roll, roller, etc. Usually, and can be performed in a temperature range of 70 to 270 ° C.

  The rubber composition of the present embodiment can be used as a vulcanized rubber by vulcanization. There are no particular restrictions on the vulcanization conditions and method, but it is preferably carried out using a vulcanization mold under a vulcanization temperature of 120 to 200 ° C. and a vulcanization pressure of 0.5 to 2.0 MPa.

[tire]
In the tire of the present embodiment, the rubber composition of the present embodiment is used at least in part. Therefore, the balance between the wet grip performance and the low fuel consumption performance is excellent, and the steering stability is also excellent.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.
Each component used in the examples and comparative examples is as follows.

Rubber component (A)
Oil-extended styrene butadiene rubber: “JSR1723” manufactured by JSR Corporation
Weight average molecular weight (Mw) = 850,000
Styrene content = 23.5% by mass
Manufactured by emulsion polymerization
Oil content = 37.5% by mass
Vinyl content = 19 mol%
Glass transition temperature (Tg) = − 53 ° C.

Silica (B)
"ULTRASIL 7000GR"
Evonik Degussa Japan wet silica: average particle size 14nm
Modified farnesene copolymer (C)
Modified farnesene copolymers C-1 to C-6 produced in the following Production Examples 1 to 6
Other Copolymers Copolymers Y-1 to Y-4 produced in Production Examples 7 to 10 below.

TDAE: “VivaTec500” H & R Silane Coupling Agent (2): “Si69” Evonik Degussa Japan Zinc Hana: “Zinc Oxide” Sakai Chemical Industry Co., Ltd. Stearic Acid: “Lunac S-20” Kao Corporation Wax: “Suntite S” Seiko Chemical Co., Ltd. Anti-aging agent (1): “NOCRACK 6C” manufactured by Ouchi Shinsei Chemical Industry

Vulcanizing agent Sulfur (fine powder 200 mesh, manufactured by Tsurumi Chemical Co., Ltd.)
Vulcanization accelerator Vulcanization accelerator (1): “Noxeller CZ-G” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Vulcanization accelerator (2): “Noxeller D” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. (3): “Noxeller TBT-N” vulcanization aid manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Also, the modified farnesene copolymer (C) and the copolymer (hereinafter referred to simply as “copolymer”) Various measurement methods related to rubber compositions and the like are as follows.

(1) Measuring method of weight average molecular weight Mw of the copolymer was calculated | required by GPC (gel permeation chromatography) by the standard polystyrene conversion molecular weight. The measuring apparatus and conditions are as follows.
・ Device: GPC device “GPC8020” manufactured by Tosoh Corporation
Separation column: “TSKgel G4000HXL” manufactured by Tosoh Corporation
Detector: “RI-8020” manufactured by Tosoh Corporation
・ Eluent: Tetrahydrofuran ・ Eluent flow rate: 1.0 ml / min ・ Sample concentration: 5 mg / 10 ml
-Column temperature: 40 ° C

(2) Method for measuring the amount of modification (Method for measuring the reaction rate of the modifying agent)
To 3 g of the sample after the denaturation reaction, 180 mL of toluene and 20 mL of ethanol were added and dissolved, and then neutralization titration with an ethanol solution of 0.1 N potassium hydroxide was performed to determine the acid value.
Acid value (mgKOH / g) = (A−B) × F × 5.661 / S
A: A drop amount of ethanol solution of 0.1N potassium hydroxide required for neutralization (mL)
B: 0.1N potassium hydroxide ethanol solution drop volume in a blank containing no sample (mL)
F: Potency of ethanol solution of 0.1N potassium hydroxide S: Weight of sample weighed (g)
The sample after the denaturation reaction was washed 4 times with methanol (5 mL relative to 1 g of the sample) to remove unreacted maleic anhydride, and then the sample was dried under reduced pressure at 80 ° C. for 12 hours. The acid value was determined by the method. The reaction rate of the modifier was calculated based on the following formula.
[Modification rate of modifier] = [Acid value after washing] / [Acid value before washing] × 100

(Equivalent functional group)
The sample after the denaturation reaction was washed with methanol four times (5 mL with respect to 1 g of the sample) to remove impurities, and then the sample was dried under reduced pressure at 80 ° C. for 12 hours. To 3 g of this sample, 180 mL of toluene and 20 mL of ethanol were added and dissolved, and then neutralization titration with an ethanol solution of 0.1 N potassium hydroxide was performed to determine the acid value.
Acid value (mgKOH / g) = (A−B) × F × 5.661 / S
A: A drop amount of ethanol solution of 0.1N potassium hydroxide required for neutralization (mL)
B: 0.1N potassium hydroxide ethanol solution drop volume in a blank containing no sample (mL)
F: Potency of ethanol solution of 0.1N potassium hydroxide S: Weight of sample weighed (g)

Next, the mass of the functional group contained per 1 g of the modified polymer (C) and the mass other than the functional group contained per 1 g (polymer main chain mass) were calculated from the acid value. The functional group equivalent (g / eq) was calculated from the following formula.
[Functional group mass per gram of polymer] = [Acid value] / [56.11] × [Functional group molecular weight] / 1,000
[Polymer main chain mass per gram of polymer] = 1- [Functional group mass per gram of polymer]
[Equivalent functional group] = [polymer main chain weight per 1 g of polymer] / ([functional group weight per 1 g of polymer] / [functional group molecular weight]

(Modification amount)
Based on the following formula, the amount of functional group (modified amount) added to 100 parts by mass of the unmodified polymer was calculated [parts by mass].
[Amount of functional group added] = [Functional group mass per 1 g of polymer] / [Polymer main chain mass per 1 g] × 100

(Average number of functional groups per molecule of polymer)
Production Examples 4-9 or Production Example 10
To 3 g of the sample after the modification reaction obtained in Production Examples 4 to 9 or Production Example 10, 180 mL of toluene and 20 mL of ethanol were added and reacted at room temperature for 30 minutes. Thereafter, the solution was vacuum-dried at 60 ° C. for 12 hours, and the obtained sample was sampled using ¹ H-NMR (500 MHz) manufactured by JEOL Ltd. at a concentration of sample / deuterated chloroform = 100 mg / 1 mL, accumulated number of times 512 times, measurement temperature. Measured at 30 ° C. The average number of functional groups per molecule of the modified polymer (C) was calculated from the area ratio of the peak derived from the methylene group of the ethyl ester in the obtained spectrum to the peak derived from the end of the polymer initiator.

(3) Measuring method of glass transition temperature (Tg) 10 mg of the copolymer after modification was sampled in an aluminum pan, and a thermogram was measured at a heating rate condition of 10 ° C./min by differential scanning calorimetry (DSC). The value of the peak top of DDSC was taken as the glass transition temperature (TgC).
Further, 10 mg of rubber component (A) was collected in an aluminum pan, a thermogram was measured under a temperature increase rate condition of 10 ° C./min by differential scanning calorimetry (DSC), and the peak top value of DDSC was determined as the glass transition temperature ( TgA).
Based on these, the value of “(TgA) − (TgC)” was calculated.
For the unmodified copolymer, the glass transition temperature (TgC ′) is measured by the same method as that for the above-mentioned modified copolymer, and the value of “(TgA) − (TgC ′)” is calculated. did.

(4) Method for Measuring Vinyl Content of Rubber Component and Modified Copolymer A solution in which 50 mg of rubber component or 50 mg of modified copolymer is dissolved in 1 ml of CDCl ₃ is measured with 1,024 integration times using 400 MHz ¹ H-NMR. did. The 4.82-5.27 ppm portion of the chart obtained by the measurement is the vinyl structure-derived spectrum in the monomer unit (3) derived from the conjugated diene compound other than farnesene, the 5.27-5.69 ppm portion The vinyl content in the monomer unit (3) was calculated as the synthetic spectrum of the vinyl structure and 1,4 bonds, based on the following formula.
{Vinyl content} = 2 × (integral value of 4.82 to 5.27 ppm) / {2 × (integral value of 5.27 to 5.69 ppm} + (integral value of 4.82 to 5.27 ppm))

(5) Method for measuring melt viscosity at 38 ° C. The melt viscosity at 38 ° C. of the copolymer was measured with a Brookfield viscometer (manufactured by BROOKFIELD ENGINEERING LABS. INC.).

(6) Rolling resistance performance at 60 ° C (low fuel consumption performance)
A test piece of 40 mm length × 7 mm width was cut out from the rubber composition sheets prepared in Examples and Comparative Examples, and measured using a dynamic viscoelasticity measuring device manufactured by GABO, measuring temperature 60 ° C., frequency 10 Hz, static strain 10 % And dynamic strain 2%, tan δ was measured and used as an index of rolling resistance. The numerical value of each Example and Comparative Example is a relative value when the value of Comparative Example 5 is 100. In addition, the rolling resistance performance of a rubber composition is so favorable that a numerical value is small.

(7) Rolling resistance performance at 0 ° C (wet grip performance)
A test piece of length 40 mm × width 7 mm was cut out from the rubber composition sheet prepared in the examples and comparative examples, and measured using a dynamic viscoelasticity measuring device manufactured by GABO, measuring temperature 0 ° C., frequency 10 Hz, static strain 10 % And dynamic strain 2%, tan δ was measured and used as an index of wet grip performance. The numerical value of each Example and Comparative Example is a relative value when the value of Comparative Example 5 is 100. In addition, the wet grip performance of a rubber composition is so favorable that a numerical value is large.

(8) Mooney viscosity As an index of processability of the rubber composition, the Mooney viscosity (ML1 + 4) of the rubber composition before vulcanization was measured at 100 ° C. in accordance with JIS K6300.
The Mooney viscosity in Table 2 is a relative value when the value of Comparative Example 5 is 100. The smaller the value, the better the workability.

(9) Elastic Modulus A test piece of 40 mm length × 7 mm width was cut out from the rubber composition sheets prepared in Examples and Comparative Examples, and measured using a dynamic viscoelasticity measuring device manufactured by GABO at a measurement temperature of 25 ° C. and a frequency of 10 Hz. The storage elastic modulus E ′ was measured under the conditions of 10% static strain and 2% dynamic strain, and used as an index of rigidity. The numerical value of each Example and Comparative Example is a relative value when the value of Comparative Example 5 is 100. In addition, the larger the numerical value, the smaller the deformation of the tire when the rubber composition is used for the tire, and the better the steering stability.

Production Example 1: Production of modified farnesene copolymer C-1 In a pressure-resistant container purged with nitrogen and dried, 580 g of cyclohexane as a solvent and 169 g of sec-butyllithium (10.5 mass% cyclohexane solution) as an initiator were charged. After the temperature was raised to 50 ° C., 3 g of tetrahydrofuran and a mixture of β-farnesene and styrene prepared in advance (1,687 g of β-farnesene and 562 g of styrene were mixed in a cylinder) were added at 22.5 g at 12.5 ml / min. Polymerized for 1 hour. The obtained polymerization reaction liquid was treated with methanol, and the polymerization reaction liquid was washed with water. The polymerization reaction solution after washing and water were separated and dried at 70 ° C. for 12 hours to obtain an unmodified farnesene-styrene random copolymer.
Next, 500 g of the unmodified farnesene-styrene random copolymer obtained in the pressure vessel, 0.5 g of Nocrack 6C as an anti-aging agent, and 25 g of maleic anhydride were charged, and after nitrogen substitution, the temperature was raised to 170 ° C. And reacted for 24 hours. Further, 9.8 g of methanol (1.2 molar equivalents relative to maleic anhydride) was added and reacted at 80 ° C. for 5 hours, whereby maleic acid-modified farnesene-styrene random copolymer C- having physical properties shown in Table 1 was obtained. 1 was obtained. The measurement results of the physical property values are shown in Table 1.

Production Example 2: Production of Modified Farnesene Copolymer C-2 A pressure-resistant container purged with nitrogen and dried was charged with 524 g of cyclohexane as a solvent and 225 g of sec-butyllithium (10.5 mass% cyclohexane solution) as an initiator, After raising the temperature to 50 ° C., 32.5 g of tetrahydrofuran and a mixture of β-farnesene, butadiene and styrene prepared in advance (1124 g of β-farnesene, 788 g of butadiene and 337 g of styrene mixed in a cylinder) 1250 ml / min And polymerized for 1 hour. The obtained polymerization reaction liquid was treated with methanol, and the polymerization reaction liquid was washed with water. The polymerization reaction solution after washing and water were separated and dried at 70 ° C. for 12 hours to obtain an unmodified farnesene-butadiene-styrene random copolymer.
Next, 500 g of the unmodified farnesene-butadiene-styrene random copolymer obtained in the pressure vessel, 0.5 g of Nocrack 6C as an antiaging agent, and 50 g of maleic anhydride were charged, and after nitrogen substitution, up to 170 ° C. The temperature was raised and reacted for 24 hours. Further, 19.6 g of methanol (1.2 molar equivalents relative to maleic anhydride) was added and reacted at 80 ° C. for 5 hours, whereby maleic acid-modified farnesene-butadiene-styrene random copolymer having the physical properties shown in Table 1 was obtained. C-2 was obtained. The measurement results of the physical property values are shown in Table 1.

Production Examples 3, 4, and 6: Production of Modified Farnesene Copolymers C-3, C-4, and C-6 In the same manner as in Production Example 2 except that the compositions shown in Table 1 were used, maleic acid-modified farnesene-butadiene- Styrene random copolymers C-3, C-4, and C-6 were obtained. The measurement results of the physical property values are shown in Table 1.

Production Example 5: Production of modified farnesene copolymer C-5 Maleic anhydride-modified farnesene-butadiene-, in the same manner as in Production Example 2, except that the composition shown in Table 1 was not used and ring-opening with methanol was not performed. Styrene random copolymer C-5 was obtained. The measurement results of the physical property values are shown in Table 1.

Production Example 7: Production of Copolymer Y-1 Copolymer Y-1 was obtained in the same manner as in Production Example 2 except that the modification was not performed and the composition shown in Table 1 was used. The measurement results of the physical property values are shown in Table 1.

Production Examples 8 to 10: Production of Copolymers Y-2 to Y-4 Copolymers Y-2 to Y-4 were obtained in the same manner as Production Example 2 except that the compositions shown in Table 1 were used. The measurement results of the physical property values are shown in Table 1.

Examples 1-6 and Comparative Examples 1-5
According to the blending ratio (parts by mass) described in Table 2, rubber component (A), filler (B), modified polymer (C), copolymer, TDAE, silane coupling agent, zinc white, stearic acid, wax The anti-aging agent and the anti-aging agent were respectively put into a closed Banbury mixer, kneaded for 6 minutes so that the starting temperature was 60 ° C. and the resin temperature was 160 ° C., then taken out of the mixer and cooled to room temperature. Subsequently, this mixture was again put into a Banbury mixer, a vulcanizing agent and a vulcanization accelerator were added, and kneaded at 100 ° C. for 75 seconds to obtain a rubber composition. The Mooney viscosity of the obtained rubber composition was measured by the above method.
Further, the obtained rubber composition is press-molded (160 ° C., 30 to 50 minutes) to produce a vulcanized rubber sheet (thickness 2 mm). Based on the above methods, low fuel consumption performance, wet grip performance, elastic modulus Evaluated. The results are shown in Table 2.

The rubber compositions of Examples 1 to 6 are excellent in the balance between wet grip performance and low fuel consumption performance, and steering stability.
On the other hand, the rubber composition of Comparative Example 1 is inferior in the balance between wet grip performance and low fuel consumption performance and steering stability because the copolymer is not modified.
Since the copolymer of Comparative Example 2 does not contain the unit (1) derived from farnesene, the rubber composition is inferior in balance between wet grip performance and low fuel consumption performance, processability, and handling stability.
The rubber composition of Comparative Example 3 is inferior in balance between wet grip performance and low fuel consumption performance and steering stability because the copolymer does not contain the unit (3) derived from the conjugated diene compound.
Since the rubber composition of Comparative Example 4 does not satisfy the condition of “−50 ° C. <(TgA) − (TgC) <30 ° C.”, it is inferior in the balance between the wet grip performance and the low fuel consumption performance and the steering stability.

Claims (6)

Rubber component (A) which is at least one selected from natural rubber, styrene butadiene rubber, butadiene rubber and isoprene rubber (however, modified farnesene copolymer (C) is not included) , filler (B) and modified farnesene Containing the polymer (C), 20 to 150 parts by mass of the filler (B) with respect to 100 parts by mass of the rubber component (A), 1 to 20 parts by mass of the modified farnesene copolymer (C),
The modified farnesene copolymer (C) is composed of one or more functional groups selected from a carboxy group, an amino group, a hydroxy group, an alkoxysilyl group, an epoxy group, a pyridine ring group, and a functional group derived from an acid anhydride (X )
A rubber composition that satisfies the following requirements (i) to (ii).
<Requirements>
(I) said modified farnesene copolymer (C) is 1 to 99 wt% of units (1) derived from farnesene, unmodified containing 1 to 99 wt% of units (2) derived from an aromatic vinyl compound A functional group (X) is introduced into the copolymer .
(Ii) The glass transition temperature (TgA) of the rubber component (A) determined by differential thermal analysis and the glass transition temperature (TgC) of the modified farnesene copolymer (C) satisfy the following relational expression.
−50 ° C. <(TgA) − (TgC) <30 ° C. The modified farnesene copolymer (C) contains units (3) derived from conjugated diene compounds other than farnesene,
The monomer unit constituting the modified farnesene copolymer (C) is 1 to 98% by mass of the unit (1) derived from farnesene and 1 to 98% by mass of the unit (2) derived from the aromatic vinyl compound. those containing 1 to 98 wt% of units (3) derived from a conjugated diene compound other than farnesene, rubber composition according to claim 1. In the modified farnesene copolymer (C), of the total amount of units (3) derived from a conjugated diene compound other than full Arunesen, the content of the monomer units having a vinyl group (vinyl content) of 90 mol% or less The rubber composition according to claim 2, wherein   The rubber composition according to any one of claims 1 to 3, wherein the modified farnesene copolymer (C) has a weight average molecular weight (Mw) of 2,000 to 500,000.   The rubber composition according to any one of claims 1 to 4, wherein the modified farnesene copolymer (C) has a melt viscosity at 38 ° C of 0.1 to 3,000 Pa · s. Tire using at least a portion of the rubber composition according to any one of claims 1-5.