JP2020007425A - Rubber composition and tire - Google Patents

Abstract

To provide a rubber composition that makes it possible to obtain a rubber molding having high hardness and excellent steering stability, and a tire at least partially comprising the rubber composition.SOLUTION: A rubber composition contains a rubber component comprising at least one of synthetic rubber and natural rubber (A), a filler (B), and a polymer containing a structural unit derived from 1,3,7-octatriene (C), with the structural unit derived from 1,3,7-octatriene having a 3,4-bond unit.SELECTED DRAWING: None

Description

  The present invention relates to a rubber composition and a tire.

  Conventionally, a rubber composition in which a filler such as carbon black is blended with a rubber component such as natural rubber or styrene-butadiene rubber and crosslinked to improve the mechanical strength is used for tires requiring abrasion resistance and mechanical strength. Widely used for applications. It is known that the carbon black exerts its reinforcing effect by physically or chemically adsorbing the rubber component on the particle surface. When a carbon black having a small average particle diameter of about 5 to 100 nm and a large specific surface area is used, the interaction between the carbon black and the rubber component becomes large, so that the mechanical strength and abrasion resistance of the rubber composition are reduced. The characteristics are improved. Further, when the rubber composition is used as a tire, the hardness is increased, so that the steering stability is improved.

  For example, Patent Literature 1 describes a rubber component for a tire containing a rubber component containing isoprene-based rubber and styrene-butadiene rubber, carbon black, and a liquid resin having a softening point of −20 to 20 ° C. in a specific ratio. ing. Patent Document 2 discloses a rubber in which a rubber component containing a diene rubber containing a modified styrene-butadiene copolymer and a modified conjugated diene polymer and a filler such as carbon black are blended in a predetermined ratio. A composition is described.

  Patent Literatures 3 and 4 disclose a method for polymerizing 1,3,7-octatriene.

JP 2011-195804 A JP 2010-209256 A Japanese Patent Publication No. 49-16269 JP-B-49-16268

According to the tire using the rubber composition described in Patent Documents 1 and 2 described above, although the hardness can be improved to some extent, it can be said that the steering stability due to the hardness has a sufficiently high level. No further improvement is desired.
Further, it is described that the polymer described in Patent Document 3 is useful as a raw material for various polymer materials, adhesives, and lubricants, but it is assumed that the polymer is used as a rubber composition. Not. Furthermore, it is described that the polymer described in Patent Document 4 is a substrate that can be converted into a useful industrial material by performing various chemical modifications utilizing its properties. It is not envisaged to use the coalesced as a rubber composition.

  An object of the present invention is to provide a rubber composition capable of obtaining a rubber molded product having high hardness and excellent steering stability, and a tire using at least a part of the rubber composition.

  The present inventors have found that a molded article of a rubber composition using a polymer containing a structural unit derived from 1,3,7-octatriene containing a 3,4-linkage unit has high hardness and steering stability. And found that the present invention was excellent.

That is, the present disclosure relates to the following.
[1] A rubber component (A) composed of at least one of synthetic rubber and natural rubber, a filler (B), and a polymer (C) containing a structural unit derived from 1,3,7-octatriene, A rubber composition wherein the structural unit derived from 1,3,7-octatriene contains a 3,4-bond unit.
[2] The structural unit derived from the 1,3,7-octatriene includes a 3,4-linkage unit and a 1,2-linkage unit, and the 3 based on the content of the 1,2-linkage unit. The rubber composition according to the above [1], wherein the ratio of the content of 3,4-linkage units (3,4-linkage units / 1,2-linkage units) is 0.04 to 0.7.
[3] The rubber composition according to the above [1] or [2], wherein the filler (B) is at least one of carbon black and silica.
[4] The rubber composition according to any one of the above [1] to [3], wherein the rubber component (A) is at least one of styrene butadiene rubber and natural rubber.
[5] The rubber composition according to any one of the above [1] to [4], wherein the polymer (C) has a weight average molecular weight (Mw) of 1,000 to 1,000,000.
[6] A tire using the rubber composition according to any one of [1] to [5] at least in part.

  Advantageous Effects of Invention According to the present invention, it is possible to provide a rubber composition capable of obtaining a rubber molded article having high hardness and excellent steering stability, and a tire using at least a part of the rubber composition.

[Rubber composition]
The rubber composition of the present invention comprises a rubber component (A) comprising at least one of synthetic rubber and natural rubber, a filler (B), and a polymer containing a structural unit derived from 1,3,7-octatriene ( C)
The structural unit derived from 1,3,7-octatriene includes a 3,4-bond unit.

<Rubber component (A)>
As the rubber component (A), a rubber composed of at least one of synthetic rubber and natural rubber is used. However, 1,3,7-octatriene is excluded. Specific examples of the rubber component (A) 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, and chloroprene rubber. And natural rubber. Among them, SBR, butadiene rubber, isoprene rubber and natural rubber are preferred, and SBR and natural rubber are more preferred. One type of these rubbers may be used, or two or more types may be used in combination.

(Synthetic rubber)
When synthetic rubber is used as the rubber component (A) in the present invention, 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. , Isoprene rubber and butadiene rubber are more preferred, and SBR is even more preferred.

(SBR (AI))
As the SBR, a general SBR used for tire applications can be used, and specifically, a styrene content of 0.2 to 81.8 mol% is preferable, and a styrene content of 9.2 to 65.8 mol% is preferable. Is more preferable, and 25.4 to 50.9 mol% is further preferable. Further, those having a vinyl content of 0.1 to 60 mol% are preferable, and those having a vinyl content of 0.1 to 55 mol% are more preferable.
In addition, the vinyl content referred to herein means a monomer unit having a 1,2-bond in a 1,4-bond or a 1,2-bond derived from all butadiene contained in SBR. Indicates the content. The weight average molecular weight (Mw) of the SBR is preferably from 100,000 to 2,500,000, more preferably from 150,000 to 2,000,000, and from 200,000 to 1,500,000. Is more preferable. When it is in the above range, both workability and mechanical strength can be achieved.

In the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are the molecular weight in terms of standard polystyrene determined by gel permeation chromatography (GPC) measurement. The molecular weight distribution (Mw / Mn) is a value calculated from them.
The glass transition temperature (Tg) of the SBR used in the present invention determined by the differential thermal analysis is preferably in the range of -95 to 0C, more preferably in the range of -95 to -5C. preferable. When the Tg is in the above range, the viscosity can be prevented from increasing, and the handling becomes easy.

<< SBR manufacturing method >>
SBR that can be used in the present invention is obtained by copolymerizing styrene and butadiene. The method for producing SBR is not particularly limited, 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 the emulsion polymerization method and the solution polymerization method are particularly preferable.

(I) Emulsion polymerization styrene butadiene rubber (E-SBR)
E-SBR can be produced by a usual emulsion polymerization method. For example, a predetermined amount of a styrene and butadiene monomer is emulsified and dispersed in the presence of an emulsifier, and emulsion-polymerized with a radical polymerization initiator.
As the emulsifier, for example, a long-chain fatty acid salt or a rosinate having 10 or more carbon atoms is used. Specific examples include potassium or sodium salts of fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, oleic acid, and stearic acid.
Water is generally used as the dispersion medium, and may contain a water-soluble organic solvent such as methanol or ethanol as long as the stability during polymerization is not impaired.
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 obtained E-SBR, a chain transfer agent can be used. Examples of the chain transfer agent include mercaptans such as tert-dodecyl mercaptan and n-dodecyl mercaptan; carbon tetrachloride, thioglycolic acid, diterpene, terpinolene, γ-terpinene, α-methylstyrene dimer and the like.

The temperature of the emulsion polymerization can be appropriately selected depending on the type of the radical polymerization initiator used, but is usually preferably 0 to 100 ° C, more preferably 0 to 60 ° C. 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-based 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, or potassium chloride is used as a coagulant, and if necessary, nitric acid, sulfuric acid, or the like is used. After coagulating the polymer while adjusting the pH of the coagulation system to a predetermined value by adding an acid, the polymer can be recovered as crumb by separating the dispersion solvent. The crumb is washed with water, then dehydrated, and then dried with a band dryer or the like to obtain E-SBR. In addition, at the time of coagulation, if necessary, a latex and an extension oil which has been previously emulsified and dispersed may be mixed and collected as an oil-extended rubber.
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 a usual solution polymerization method. For example, styrene and butadiene are polymerized using an active metal capable of anion polymerization in a solvent, if necessary, 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; and lanthanoid rare earth metals such as lanthanum and neodymium. . Among them, alkali metals and alkaline earth metals are preferred, and alkali metals are more preferred. 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; And the like. 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, tert-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 and potassium naphthalene; Among them, organic lithium compounds are preferable, and organic monolithium compounds are 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 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 a compound generally used for adjusting the microstructure of the butadiene site and the distribution of the styrene in the copolymer chain, without inactivating the reaction in the anionic polymerization. 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 150C, preferably 0 to 100C, more preferably 30 to 90C. The polymerization mode may be a batch type or a continuous type. In addition, in order to improve the random copolymerizability 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. Before adding the polymerization terminator, coupling of tin tetrachloride, tetrachlorosilane, tetramethoxysilane, tetraglycidyl-1,3-bisaminomethylcyclohexane, 2,4-tolylene diisocyanate, etc., which can react with the polymerization active terminal. And a polymerization terminal modifier such as 4,4′-bis (diethylamino) benzophenone and N-vinylpyrrolidone. After the termination of the polymerization reaction, the solvent can be separated from the polymerization solution by direct drying, steam stripping, or the like, and the desired S-SBR can be recovered. Before removing the solvent, the polymerization solution and the extender oil may be mixed in advance and collected as an oil-extended rubber.

(Iii) Modified styrene butadiene rubber (modified SBR)
In the present invention, a modified SBR in which a functional group has been introduced into SBR may be used. Examples of the functional group include an amino group, an alkoxysilyl group, a hydroxy group, an epoxy group, a carboxyl group, and the like.
As a method for producing the modified SBR, for example, before adding a polymerization terminator, tin tetrachloride capable of reacting with a polymerization active terminal, tetrachlorosilane, dimethyldichlorosilane, dimethyldiethoxysilane, tetramethoxysilane, tetraethoxysilane, 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 another modifier described in JP-A-2011-132298.
In this modified SBR, the position of the polymer into which the functional group is introduced may be a polymerization terminal or a side chain of a polymer chain.

(Isoprene rubber (A-II))
Examples of the isoprene rubber include Ziegler catalysts such as titanium tetrahalide-trialkylaluminum, diethylaluminum chloride-cobalt, trialkylaluminum-boron trifluoride-nickel, and diethylaluminum chloride-nickel; -A commercially available isoprene rubber polymerized using a lanthanoid-based rare earth metal catalyst such as an organic acid neodymium-Lewis acid-based 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 content. Further, an isoprene rubber having an ultra-high cis content obtained by using a lanthanoid-based 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 is 50 mol% or less, the rolling resistance performance becomes good. The lower limit of the vinyl content is not particularly limited.
Here, the vinyl content refers to a 3,4-bond and a 1,2-bond in a monomer unit composed of 1,4-bond, 1,2-bond and 3,4-bond in isoprene rubber. Represents the percentage of the content.
The glass transition temperature varies depending on the vinyl content, but is preferably -20C or lower, more preferably -30C or lower.
The weight average molecular weight (Mw) of the isoprene rubber is preferably from 90,000 to 2,000,000, and more preferably from 150,000 to 1,500,000. When Mw is in the above range, workability and mechanical strength are good.
The isoprene rubber is partially modified with a polyfunctional modifier such as tin tetrachloride, silicon tetrachloride, an alkoxysilane having an epoxy group in the molecule, or an amino group-containing alkoxysilane. It may have a branched structure or a polar functional group.

(Butadiene rubber (A-III))
Examples of the butadiene rubber include Ziegler catalysts such as titanium tetrahalide-trialkylaluminum, diethylaluminum chloride-cobalt, trialkylaluminum-boron trifluoride-nickel, and diethylaluminum chloride-nickel; triethylaluminum -Commercially available butadiene rubber polymerized using a lanthanoid-based rare earth metal catalyst such as an organic acid neodymium-Lewis acid-based or an organic alkali metal compound as in S-SBR can be used. Butadiene rubber polymerized with a Ziegler catalyst is preferred because of its high cis content. Further, a butadiene rubber having an ultra-high cis content obtained using a lanthanoid-based rare earth metal catalyst may be used.
The vinyl content of the butadiene rubber is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less. When the vinyl content is 50% by mass or less, the rolling resistance performance becomes good. 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, more preferably -50 ° C or lower.
In addition, the vinyl content here represents the ratio of the content of 1,2-bond in the monomer unit composed of 1,4-bond and 1,2-bond in butadiene rubber.
The weight average molecular weight (Mw) of the butadiene rubber is preferably from 90,000 to 2,000,000, and more preferably from 150,000 to 1,500,000. When Mw is in the above range, workability and mechanical strength are good.
The butadiene rubber is partially modified with a polyfunctional modifier, for example, by using a modifier such as tin tetrachloride, silicon tetrachloride, an alkoxysilane having an epoxy group in a molecule, or an amino group-containing alkoxysilane. It may have a branched structure or a polar functional group.

  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 together with at least one of SBR, isoprene rubber and butadiene rubber. The method for producing these is not particularly limited, and commercially available ones can be used.

(Natural rubber)
Examples of the natural rubber used in the rubber component (A) include TSR such as SMR, SIR and STR, and natural rubber generally used in the tire industry such as RSS, high-purity natural rubber, epoxidized natural rubber, and hydroxylated rubber. Modified natural rubbers such as natural rubber, hydrogenated natural rubber, and grafted natural rubber are exemplified. Above all, SMR20, STR20 and RSS # 3 are preferable from the viewpoint of small variation in quality and availability. These may be used alone or in combination of two or more.
The method for producing the rubber used for the rubber component (A) is not particularly limited, and a commercially available rubber may be used.

  In the present invention, the content of the rubber component (A) in the rubber composition is preferably 20 to 99.9% by mass, more preferably 25 to 80% by mass, and still more preferably 30 to 70% by mass.

<Filler (B)>
The filler (B) has an effect of improving physical properties such as mechanical strength of a crosslinked product of the rubber composition. It is preferable to use at least one of carbon black and silica as the filler (B).
〔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 preferred from the viewpoint of improving the vulcanization rate and mechanical strength.
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 dispersibility, mechanical strength, and hardness.
As carbon black having an average particle diameter of 5 to 100 nm, examples of commercially available furnace black include "Diablack" manufactured by Mitsubishi Chemical Corporation and "Seast" manufactured by Tokai Carbon Co., Ltd. Examples of commercially available acetylene black include “DENKA BLACK” manufactured by Denki Kagaku Kogyo Co., Ltd. As a commercially available product of Ketjen Black, for example, “ECP600JD” manufactured by Lion Corporation can be mentioned.

From the viewpoint of improving the wettability and dispersibility of the rubber component (A) and the polymer (C) described below, the carbon black is treated with an acid such as nitric acid, sulfuric acid, hydrochloric acid or a mixed acid thereof, or in the presence of air. Surface oxidation treatment by heat treatment in the above. From the viewpoint of improving the mechanical strength of the rubber composition of the present invention, heat treatment may be performed at 2,000 to 3,000 ° C. in the presence of a graphitization catalyst. Examples of the graphitization catalyst include boron, boron oxide (eg, B ₂ O ₂ , B ₂ O ₃ , B ₄ O ₃ , B ₄ O ₅ ), boron oxo acid (eg, orthoboric acid, metaboric acid, Tetraboric acid and the like, 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 the carbon black can be adjusted by pulverization or the like. For grinding carbon black, high-speed rotary mills (hammer mills, pin mills, cage mills), various ball mills (rolling mills, vibration mills, planetary mills), stirring mills (bead mills, attritors, flow tube mills, annular mills) Etc. can be used.
The average particle size of the carbon black can be determined by measuring the particle diameter with a transmission electron microscope and calculating the average value.

  When the rubber composition of the present invention contains carbon black, the content is preferably 0.1 to 120 parts by mass, more preferably 5 to 90 parts by mass, based on 100 parts by mass of the rubber component (A). More preferably, it is 10 to 80 parts by mass. When the content of carbon black is within the above range, the hardness of the obtained rubber molded product can be increased, and the steering stability can be improved.

〔silica〕
Examples of the silica include wet silica (hydrous silicic acid), dry silica (silicic anhydride), calcium silicate, aluminum silicate and the like. Among them, wet silica is preferable from the viewpoint of further improving mechanical strength and wear resistance. 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, and more preferably 5 to 150 nm, from the viewpoint of improving the processability, rolling resistance performance, mechanical strength, and abrasion resistance of the obtained rubber composition. 100 nm is more preferred.
The average particle size of the silica can be determined by measuring the particle diameter with a transmission electron microscope and calculating the average value.

  When the rubber composition of the present invention contains silica, the content is preferably 0.1 to 120 parts by mass, more preferably 5 to 90 parts by mass, based on 100 parts by mass of the rubber component (A). Preferably it is 10 to 80 parts by mass. When the content of silica is within the above range, the hardness of the obtained rubber molded product can be further improved.

[Other fillers]
The rubber composition of the present invention may further contain fillers other than silica and carbon black as needed, for the purpose of improving mechanical strength, adjusting hardness, improving economic efficiency by blending an extender, and the like. Good.

  The filler other than silica and carbon black is appropriately selected depending on the application.For example, an organic filler, clay, talc, mica, calcium carbonate, magnesium hydroxide, aluminum hydroxide, barium sulfate, titanium oxide, One or more inorganic fillers such as glass fiber and glass balloon can be used.

<Polymer (C) containing a structural unit derived from 1,3,7-octatriene containing a 3,4-linkage unit>
The rubber composition of the present invention comprises a polymer (C) containing a structural unit derived from 1,3,7-octatriene containing a 3,4-linkage unit (hereinafter, also simply referred to as polymer (C)). contains. In the present invention, since the rubber component (A), the filler (B), and the polymer (C) are used in combination, a rubber composition capable of providing a rubber molded product having high hardness and excellent steering stability is obtained. be able to.
Although the gist and technical scope of the present invention are not limited at all, it is based on the fact that the structural unit derived from 1,3,7-octatriene contained in the polymer (C) contains a 3,4-bond unit. It is considered that the improvement in hardness of the rubber composition is caused by the following effects.
That is, since the 3,4-bond unit is contained in the structural unit derived from 1,3,7-octatriene included in the polymer (C), a double bond is provided at two terminal ends of the side chain. It is considered that the polymer (C) and the rubber component (A) are easily vulcanized, and the hardness of the obtained rubber molded product can be increased.

  The structural unit derived from 1,3,7-octatriene includes a 1,2-linkage unit, a 1,4-linkage unit, and a 4,1-linkage unit in addition to a 3,4-linkage unit. There is no particular limitation on the bonding order of each bonding unit. In the present invention, the 1,4-linkage unit and the 4,1-linkage unit are regarded as the same.

  The polymer (C) contains a structural unit derived from 1,3,7-octatriene, and if the structural unit derived from 1,3,7-octatriene contains a 3,4-bonded unit, Not limited. Among them, the content ratio of the 3,4-bond unit contained in the structural unit derived from 1,3,7-octatriene is preferably 2 mol% or more, more preferably from the viewpoint of exhibiting the effect of the present invention. It is 2 to 40 mol%, more preferably 2 to 35 mol%.

The content ratio of the 1,2-linking unit contained in the structural unit derived from 1,3,7-octatriene is preferably 35 to 65 mol%, more preferably 40 to 60 mol%, and still more preferably 40 to 60 mol%. 50 mol%.
The content ratio of the 1,4-linkage unit contained in the structural unit derived from 1,3,7-octatriene is defined as the content ratio of the 3,4-linkage unit and the content ratio of the 1,2-linkage unit. The rest will be taken into account. That is, the content ratio of the 1,4-bond is determined from "100- (content ratio of 3,4-bond unit + content ratio of 1,2-bond unit)".
The content ratio of each binding unit is determined by ¹³ C-NMR measurement. Specifically, it can be determined according to the method described in the examples.

Further, the ratio of the content of the 3,4-linking unit to the content of the 1,2-linking unit (3,4-linking unit / 1,2-linking unit) is preferably 0.04 to 0.5. 7, more preferably 0.045 to 0.6, still more preferably 0.05 to 0.5, even more preferably 0.1 to 0.45, and particularly preferably 0.12 to 0.4. When the ratio (3,4-linkage unit / 1,2-linkage unit) is 0.04 or more, the side chain terminal of the 3,4-linkage unit of the structural unit derived from 1,3,7-octatriene In the rubber component (A), the vulcanization with the rubber component (A) is facilitated, and the hardness of the obtained rubber molded product can be increased. When it is 0.7 or less, an increase in the side chain density is suppressed. , Tg and viscosity are suppressed, and handling becomes easy.
The ratio (3,4-bonded unit / 1,2-bonded unit) can be adjusted to the above range by appropriately adjusting the polymerization temperature and the amount of the Lewis base.

The polymer (C) may be composed of only a structural unit derived from 1,3,7-octatriene, and a structural unit derived from 1,3,7-octatriene and 1,3,7-octatriene. It may be composed of a structural unit derived from a monomer other than octatriene.
When the polymer (C) is a copolymer, examples of the monomer other than 1,3,7-octatriene include conjugated diene compounds having 4 or more carbon atoms, aromatic vinyl compounds, and other vinyl compounds. Can be mentioned.
Examples of the conjugated diene compound having 4 or more carbon atoms include butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 4,5-diethyl-1,3-butadiene, and 2-phenyl-1,3-butadiene. , 2-hexyl-1,3-butadiene, 2-benzyl-1,3-butadiene, 2-p-toluyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3 -Pentadiene, 2,3-dimethyl-1,3-pentadiene, 2,3-diethyl-1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-hexadiene, 2,3-diethyl -1,3-heptadiene, 3-butyl-1,3-octadiene, 2,3-dimethyl-1,3-octadiene, 4,5-diethyl-1,3-octadiene, 1,3-cyclo Hexadiene, myrcene (7-methyl-3-methylene-octa-1,6-diene) and the like. Among them, at least one selected from the group consisting of butadiene and isoprene is preferable.

  Examples of the aromatic vinyl compound include styrene, α-methylstyrene, α-methyl-4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, and 4-tert-butyl. Styrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 4-n-propylstyrene, 4-isopropylstyrene, 4-tert-butylstyrene, 2,4-diisopropylstyrene, 2,4,6-trimethylstyrene, 2-ethyl-4-benzylstyrene, -(Phenylbutyl) styrene, 4- (4-phenyl-n-butyl) Styrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, 1,2-divinylbenzene, 1,3-divinylbenzene, 1,4-divinylbenzene, 1,2-divinyl-3,4-dimethylbenzene, 2,4-divinylbiphenyl, 1,3-divinylnaphthalene, 1,2,4-trivinylbenzene , 3,5,4'-trivinylbiphenyl, 1,3,5-trivinylnaphthalene, 1,5,6-trivinyl-3,7-diethylnaphthalene, vinylanthracene, N, N-diethyl-4-aminoethyl Styrene, vinylpyridine, 4-methoxystyrene, monochlorostyrene, dichlorostyrene, divinylbenzene, 2-chloro Rosuchiren, 4-chlorostyrene, and the like. Among them, styrene, α-methylstyrene and 4-methylstyrene are preferred.

  As other vinyl compounds, for example, acrylonitrile, methacrylonitrile, α, β-unsaturated nitrile such as ethacrylonitrile; acrylic acid, methacrylic acid, crotonic acid, 3-methylcrotonic acid, 3-butenoic acid, maleic acid, Α, β-unsaturated carboxylic acids such as fumaric acid, itaconic acid, citraconic acid, and mesaconic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, sec-butyl acrylate, tert-acrylic acid Butyl, hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, sec-butyl methacrylate, methacrylic acid -Tert Butyl, hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate, dibutyl fumarate, dimethyl itaconate, itacon Α, β-unsaturated carboxylic acid esters such as diethyl citrate and dibutyl itaconate; N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, N-butylacrylamide, N-octylacrylamide, N-phenylacrylamide, N- Glycidyl acrylamide, N, N'-ethylenebisacrylamide, N, N-dimethylacrylamide, N-ethyl-N-methylacrylamide, N, N-diethylacrylamide, N, N-dipro Ruacrylamide, N, N-dioctylacrylamide, N, N-diphenylacrylamide, N-ethyl-N-glycidylacrylamide, N, N-diglycidylacrylamide, N-methyl-N- (4-glycidyloxybutyl) acrylamide, N -Methyl-N- (5-glycidyloxypentyl) acrylamide, N-methyl-N- (6-glycidyloxyhexyl) acrylamide, N-acryloylpyrrolidine, N-acryloyl-L-proline methyl ester, N-acryloylpiperidine, N -Acryloylmorpholine, 1-acryloylimidazole, N, N'-diethyl-N, N'-ethylenebisacrylamide, N, N'-dimethyl-N, N'-hexamethylenebisacrylamide, di (N, N'-ethylene ) Bisua And acrylamide such as acrylamide. These may be used alone or in combination of two or more.

  Other than 1,3,7-octatriene to the total of the structural units derived from 1,3,7-octatriene and the structural units derived from monomers other than 1,3,7-octatriene in the copolymer The proportion of the structural unit derived from the monomer is preferably from 10 to 80 mol%, more preferably from 20 to 70 mol%, from the viewpoint of obtaining the effect due to the side chain of 1,3,7-octatriene. More preferably, it is 30 to 60 mol%.

  In the copolymer, 1,3,7-octatriene relative to the total amount of structural units derived from 1,3,7-octatriene and structural units derived from monomers other than 1,3,7-octatriene Is preferably 10 mol% or more, more preferably 20 mol% or more (mol%; sometimes referred to as 1,3,7-octatriene content α). It is more preferably at least 30 mol%, particularly preferably at least 40 mol%. The upper limit of the 1,3,7-octatriene content α is not particularly limited, but may be 99 mol% or less, 90 mol% or less, or 80 mol% or less. Or 70 mol% or less, or 60 mol% or less.

In the copolymer, the bonding mode of the conjugated diene compound is not particularly limited, and the bonding order and the content of each bonding mode are not particularly limited. For example, typical bonding modes of butadiene include a 1,2-bond and a 1,4-bond, and the bonding order and the content of each bonding mode are not particularly limited.
Regarding the binding mode of butadiene, for example, the content ratio of 1,2-bonds to the total binding mode is preferably 5 to 60 mol%, more preferably 10 to 50 mol%, and still more preferably 15 to 45 mol%. Is more preferable. The content of 1,4-bonds in all bonding modes is the balance of the content of 1,2-bonds in all bonding modes.

In addition, typical bonding modes of isoprene include 1,2-bond, 3,4-bond, and 1,4-bond, and the bonding order and the content ratio of each bonding mode are not particularly limited.
Regarding the bonding mode of isoprene, for example, the content ratio of 1,4-bonds to all bonding modes is preferably 40 to 95 mol%, more preferably 50 to 90 mol%, and more preferably 50 to 85 mol%. Is more preferable, and even more preferably 60 to 85 mol%. The content ratio of the 3,4-bond relative to the total bonding mode is preferably 5 to 60 mol%, more preferably 5 to 50 mol%, further preferably 5 to 40 mol%, and 15 It is even more preferred that the content is ４０40 mol%. The content of 1,2-bonds with respect to all bonding modes is the balance in consideration of the content of 1,4-bonds and the content of 3,4-bonds.
The ratio of each bonding mode is determined by ¹³ C-NMR measurement.

  In the copolymer, the bonding form between the structural unit derived from 1,3,7-octatriene and the structural unit derived from a monomer other than 1,3,7-octatriene is particularly limited. However, random, completely alternating, gradient, block, tapered, and combinations thereof are mentioned, and random or block is preferable, and random is more preferable from the viewpoint of manufacturability.

  The weight average molecular weight (Mw) of the polymer (C) is preferably from 1,000 to 1,000,000, more preferably from 4,000 to 500,000, from the viewpoint of increasing hardness and improving steering stability. More preferably, it is from 7,000 to 200,000, even more preferably from 13,000 to 200,000, particularly preferably from 50,000 to 180,000.

When carbon black having a small average particle size is used as the filler (B), the dispersibility of the carbon black in the rubber composition decreases due to the high cohesive force between the carbon blacks. When the dispersibility is reduced, the rubber composition tends to generate heat, so that the rolling resistance of the molded product is deteriorated, and the required characteristics of a so-called fuel-efficient tire may not be satisfied.
In the present invention, the rolling resistance performance is further improved by setting the weight average molecular weight (Mw) of the polymer (C) to preferably 50,000 to 180,000, more preferably 62,000 to 170,000. Can be.

  The molecular weight distribution (Mw / Mn) of the polymer (C) is preferably 4.0 or less, more preferably 3.0 or less, still more preferably 2.5 or less, and even more preferably 2.0 or less. The lower limit of the molecular weight distribution (Mw / Mn) is not particularly limited, but is usually 1.0 or more, and may be 1.05 or more.

The polymer (C) may or may not contain a structural unit derived from a coupling agent. When the polymer (C) contains a structural unit derived from a coupling agent, the content of the structural unit derived from the coupling agent is preferably 5 mol% or less, and more preferably 2 mol% in all the structural units. It is more preferred that:
Examples of the coupling agent include: divinylbenzene; polyepoxy compounds such as epoxidized 1,2-polybutadiene, epoxidized soybean oil, tetraglycidyl-1,3-bisaminomethylcyclohexane; tin tetrachloride, tetrachlorosilane; Halides such as trichlorosilane, trichloromethylsilane, dichlorodimethylsilane, dibromodimethylsilane; methyl benzoate, ethyl benzoate, phenyl benzoate, diethyl oxalate, diethyl malonate, diethyl adipate, dimethyl phthalate, dimethyl terephthalate Ester compounds such as dimethyl carbonate, diethyl carbonate and diphenyl carbonate; diethoxydimethylsilane, trimethoxymethylsilane, triethoxymethylsilane, tetramethoxysilane, tetraethoxy Shishiran, tetrabutoxysilane, tetrakis (2-ethylhexyl oxy) silane, bis (triethoxysilyl) ethane, an alkoxysilane compounds such as 3-aminopropyltriethoxysilane; 2,4-tolylene diisocyanate, and the like.

  The polymer (C) is a polymer having no living anion active species at the molecular terminal at the stage after the reaction with the terminal stopper after the polymerization reaction when produced by anionic polymerization described below. In addition, when the polymer (C) is produced by anionic polymerization described below, at the stage before the reaction with a terminal terminator after the polymerization reaction, a polymer having a living anion active species at a molecular terminal (referred to as a living anion polymer) There are times.)

(Hydride)
The polymer (C) may be a hydride of the polymer (C) from the viewpoint of heat resistance and weather resistance. When the polymer (C) is a hydride, the hydrogenation rate is not particularly limited, but in the polymer (C), at least 80 mol% of carbon-carbon double bonds are hydrogenated (hereinafter also referred to as hydrogenation). However, it is preferable that 85 mol% or more is hydrogenated, more preferably 90 mol% or more is hydrogenated, and 93 mol% is more preferable. It is particularly preferred that the above is hydrogenated, and it is most preferred that 95 mol% or more is hydrogenated. The value may be referred to as a hydrogenation rate (hydrogenation rate). The upper limit of the hydrogenation rate is not particularly limited, but may be 99 mol% or less.
The hydrogenation rate can be determined by ¹ H-NMR measurement after hydrogenation of the content of carbon-carbon double bonds.

  The content of the polymer (C) is preferably 1 to 50 parts by mass, more preferably 5 to 40 parts by mass, and still more preferably 8 to 30 parts by mass with respect to 100 parts by mass of the rubber component (A). When the content of the polymer (C) is within the above range, the hardness of the obtained rubber molded product can be increased, and the steering stability can be improved.

  It does not matter whether the polymer (C) and the rubber component (A) have a phase-separated structure, but when the phase-separated structure is formed, tan δ of the obtained vulcanized rubber increases, and it is difficult to improve the rolling resistance performance. It may be. Further, the compatibility of the phase separation interface between the polymer (C) and the rubber component (A) is reduced, and the mechanical properties such as the breaking strength of the obtained vulcanized rubber are easily reduced, so that no phase separation structure is formed. Is preferred.

  The presence or absence of a phase-separated structure between the polymer (C) and the rubber component (A) can be determined from Tg by a differential scanning calorimeter (DSC) or tan δ peak shape by dynamic viscoelasticity measurement. That is, when Tg or tan δ shows a single value, it means that the polymer (C) and the rubber component (A) are in a state of being compatible in a nanometer order (molecular level). In particular, judgment by dynamic viscoelasticity measurement is preferable.

[Method for producing polymer (C)]
The polymer (C) can be produced by performing anionic polymerization using 1,3,7-octatriene as a raw material.
There is no particular limitation on the anionic polymerization method, and a known anionic polymerization method can be used.
For example, 1,3,7-octatriene and a monomer other than the 1,3,7-octatriene used as necessary (the raw material to be polymerized may be referred to as a raw material monomer hereinafter). A polymerization reaction is carried out by supplying an anionic polymerization initiator to the mixture of the above and a polymer having a living anion active species is formed in the reaction system. Next, the polymer (C) can be produced by adding a polymerization terminator.
Moreover, you may use a Lewis base and a solvent as needed.

  The polymerization reaction is preferably performed, for example, in a reactor pressurized with an inert gas in order to prevent water, oxygen, and the like that inhibit the polymerization reaction from entering the reaction system. By using an inert gas atmosphere, consumption of the anionic polymerization initiator and the growth terminal anion by the reaction with water or oxygen can be suppressed, and the polymerization reaction can be controlled with high accuracy. The term "growth terminal anion" as used herein refers to an anion that a polymer present in a reaction system during a polymerization reaction has at a molecular terminal, and the same applies hereinafter.

Materials used in the production of the polymer, raw material monomers, anionic polymerization initiators described below, Lewis bases described below and solvents described below are substances that react with the growth terminal anions and inhibit the polymerization reaction, such as oxygen and water. , A hydroxy compound, a carbonyl compound, an alkyne compound, and the like, and are preferably stored under an inert gas atmosphere such as nitrogen, argon, or helium under light shielding.
The raw material monomer, anionic polymerization initiator, Lewis base and the like may be used after being diluted with a solvent, respectively, or may be used without dilution with a solvent.

(Anionic polymerization initiator)
Since the method for producing the polymer (C) utilizes anionic polymerization, an anionic polymerization initiator is used. The type of the anionic polymerization initiator is not limited as long as it is a compound that can initiate anionic polymerization.
As the anionic polymerization initiator, an organic alkali metal compound generally used in anionic polymerization of an aromatic vinyl compound and a conjugated diene compound can be used. Examples of the organic alkali metal compound include, for example, methyl lithium, ethyl lithium, propyl lithium, isopropyl lithium, butyl lithium, sec-butyl lithium, tert-butyl lithium, isobutyl lithium, pentyl lithium, hexyl lithium, butadienyl lithium, Cyclohexyllithium, phenyllithium, benzyllithium, p-tolyllithium, styryllithium, trimethylsilyllithium, 1,4-dilithiobutane, 1,5-dilithiopentane, 1,6-dilithiohexane, 1,10-dilithiodecane, 1,1- Dilithiodiphenylene, dilithiopolybutadiene, dilithiopolyisoprene, 1,4-dilithiobenzene, 1,2-dilithio-1,2-diphenylethane, 1,4-dilithio-2-ethyl Organic lithium compounds such as chlorohexane, 1,3,5-trilithiobenzene, 1,3,5-trilithio-2,4,6-triethylbenzene; methyl sodium, ethyl sodium, n-propyl sodium, isopropyl sodium, n Organic sodium compounds such as -butyl sodium, sec-butyl sodium, tert-butyl sodium, isobutyl sodium, phenyl sodium, sodium naphthalene, and cyclopentadienyl sodium. Among them, n-butyllithium and sec-butyllithium are preferable. One type of organic alkali metal compound may be used, or two or more types may be used in combination.

  The amount of the anionic polymerization initiator used can be appropriately set according to the desired polymer weight average molecular weight or the solid content of the reaction solution. For example, the amount of the raw material monomer / anionic polymerization initiator (molar ratio) is determined as follows. It is preferably from 10 to 3,000, more preferably from 20 to 2,500, further preferably from 30 to 2,000, and particularly preferably from 40 to 1,500.

(Lewis base)
In the method for producing the polymer (C), the viewpoint of controlling the polymerization reaction, in particular, the structural unit derived from 1,3,7-octatriene and the structural unit derived from a conjugated diene other than 1,3,7-octatriene From the viewpoint of controlling the bonding unit in the above, a Lewis base may be used, and it is preferable to use a Lewis base. The type of the Lewis base is not particularly limited as long as it is an organic compound that does not substantially react with the anionic polymerization initiator and the growth terminal anion.
When a Lewis base is used, the molar ratio (Lewis base / polymerization initiator) of the Lewis base and the polymerization initiator (anionic polymerization initiator) used for anionic polymerization is preferably 0.01 to 1,000. , 0.01 to 400, more preferably 0.1 to 200, still more preferably 0.1 to 50, and particularly preferably 0.1 to 22. Within this range, in particular, the ratio of the content of 3,4-linking unit to the content of 1,2-linking unit in the structural unit derived from 1,3,7-octatriene (3,4-linking unit) / 1,2-bonded unit) falls within the above preferred range. Also, it is easy to achieve a high conversion of 1,3,7-octatriene in a short time.

As the Lewis base, (i) a compound having at least one selected from the group consisting of an ether bond and a tertiary amino group in the molecule [hereinafter, referred to as Lewis base (i). And among the Lewis bases (i), (i-1) a compound having one atom having an unshared electron pair [hereinafter, referred to as a Lewis base (i-1). And (i-2) a compound having two or more atoms having an unshared electron pair [hereinafter referred to as Lewis base (i-2). ].
The Lewis base may be one having monodentate coordination or one having multidentate coordination. In addition, one type of Lewis base may be used, or two or more types may be used in combination.

  Specific examples of the Lewis base (i-1) include dimethyl ether, methyl ethyl ether, diethyl ether, ethyl propyl ether, dipropyl ether, diisopropyl ether, butyl methyl ether, tert-butyl methyl ether, dibutyl ether, dioctyl ether, ethyl Acyclic monoethers such as phenyl ether and diphenyl ether; cyclic monoethers preferably having a total of 2 to 40 (more preferably 2 to 20) total carbon atoms, such as tetrahydrofuran (THF) and tetrahydropyran; trimethylamine, triethylamine, triethylamine Propylamine, triisopropylamine, tributylamine, triisobutylamine, trisec-butylamine, tritert-butylamine, tritert-hexylamine, tripropylamine tert-octylamine, tritert-decylamine, tritert-dodecylamine, tritert-tetradecylamine, tritert-hexadecylamine, tritert-octadecylamine, tritert-tetracosanylamine, tritert-octakosani Amine, 1-methyl-1-amino-cyclohexane, tripentylamine, triisopentylamine, trineopentylamine, trihexylamine, triheptylamine, trioctylamine, triphenylamine, tribenzylamine, N, N- Dimethylethylamine, N, N-dimethylpropylamine, N, N-dimethylisopropylamine, N, N-dimethylbutylamine, N, N-dimethylisobutylamine, N, N-dimethylsec-butylamine, N, N-dimethyltert-butylamine, N, N-dimethylpentylamine, N, N-dimethylisopentylamine, N, N-dimethylneopentylamine, N, N-dimethylhexylamine, N, N-dimethylheptylamine, N, N-dimethyloctylamine, N, N-dimethylnonylamine, N, N-dimethyldecylamine, N, N-dimethylundecylamine, N, N-dimethyldodecylamine, N, N-dimethylphenylamine, N , N-dimethylbenzylamine, N, N-diethylmonomethylamine, N, N-dipropylmonomethylamine, N, N-diisopropylmonomethylamine, N, N-dibutylmonomethylamine, N, N-diisobutylmonomethylamine, N-disec-butylmonomethylamine, N, N-dit rt-butyl monomethylamine, N, N-dipentyl monomethylamine, N, N-diisopentyl monomethylamine, N, N-dineopentyl monomethylamine, N, N-dihexyl monomethylamine, N, N-diheptyl monomethylamine N, N-dioctylmonomethylamine, N, N-dinonylmonomethylamine, N, N-didecylmonomethylamine, N, N-diundecylmonomethylamine, N, N-didodecylmonomethylamine, N, N-diphenyl Monomethylamine, N, N-dibenzylmonomethylamine, N, N-dipropylmonomethylamine, N, N-diisopropylmonoethylamine, N, N-dibutylmonoethylamine, N, N-diisobutylmonoethylamine, N, N-di sec-butyl monoethylamine, N, N- Di-tert-butyl monoethylamine, N, N-dipentyl monoethylamine, N, N-diisopentyl monoethylamine, N, N-dineopentyl monoethylamine, N, N-dihexyl monoethylamine, N, N-diheptyl mono Ethylamine, N, N-dioctylmonoethylamine, N, N-dinonylmonoethylamine, N, N-didecylmonoethylamine, N, N-diundecylmonoethylamine, N, N-didodecylmonoethylamine, N, N- Preferably, such as diphenylmonoethylamine, N, N-dibenzylmonoethylamine, N, N-dimethylaniline, N, N-diethylaniline, N-ethylpiperazine, N-methyl-N-ethylaniline, N-methylmorpholine and the like. Total carbon number 3 to 60 (more preferably total carbon number 3 to 1) Such as tertiary monoamines), and the like.

The Lewis base (i-1) is a Lewis base having monodentate coordination with respect to the metal atom of the anionic polymerization initiator.
As the Lewis base (i-1), a structural unit derived from 1,3,7-octatriene and a structural unit derived from a conjugated diene other than 1,3,7-octatriene are used in view of controlling a polymerization reaction. From the viewpoint of controlling the bonding unit in the above, diethyl ether, diisopropyl ether, tetrahydrofuran, tetrahydropyran, triethylamine, and N, N-dimethylethylamine are preferred.
When the Lewis base (i-1) is used, the molar ratio of the atom having the lone pair in the Lewis base (i-1) to the metal atom of the polymerization initiator used in the anionic polymerization (the lone pair) is used. Is preferably from 0.01 to 1,000, more preferably from 0.1 to 500, still more preferably from 2 to 300, and more preferably from 2 to 100. Is particularly preferred, and most preferably 2 to 50. Within this range, in particular, the ratio of the content of 3,4-linking unit to the content of 1,2-linking unit in the structural unit derived from 1,3,7-octatriene (3,4-linking unit) / 1,2-bonded unit) falls within the above preferred range. Also, it is easy to achieve a high conversion of 1,3,7-octatriene in a short time.

  Specific examples of the Lewis base (i-2) include 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-diisopropoxyethane, 1,2-dibutoxyethane, and 1,2-dimethoxyethane. Phenoxyethane, 1,2-dimethoxypropane, 1,2-diethoxypropane, 1,2-diphenoxypropane, 1,3-dimethoxypropane, 1,3-diethoxypropane, 1,3-diisopropoxypropane, 1,3-dibutoxypropane, 1,3-diphenoxypropane and the like, preferably an acyclic diether having a total carbon number of 4 to 80 (more preferably a total of 4 to 40 carbon atoms); A cyclic diether having preferably a total of 4 to 80 (more preferably 4 to 40) carbon atoms, such as 2-di (tetrahydrofuryl) propane; diethylene glycol di Methyl ether, dipropylene glycol dimethyl ether, dibutylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol diethyl ether, dibutylene glycol diethyl ether, triethylene glycol dimethyl ether, tripropylene glycol dimethyl ether, tributylene glycol dimethyl ether, triethylene glycol diethyl ether, Tripropylene glycol diethyl ether, tributylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetrapropylene glycol dimethyl ether, tetrabutylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetrapropylene glycol diethyl ether A non-cyclic polyether having preferably a total of 6 to 40 (more preferably a total of 6 to 20) carbon atoms, such as tetrabutylene glycol diethyl ether; N, N, N ', N'-tetramethylethylenediamine (TMEDA); Preferably, the total carbon number of N, N, N ', N'-tetraethylethylenediamine, N, N, N, N ", N" -pentamethyldiethylenetriamine, tris [2- (dimethylamino) ethyl] amine, etc. Examples thereof include polyamines having 6 to 122 (more preferably 6 to 32 total carbon atoms, and still more preferably 6 to 15 total carbon atoms).

The Lewis base (i-2) includes a Lewis base having monodentate coordination with respect to the metal atom of the anionic polymerization initiator, and a Lewis base having polydentate coordination with respect to the metal atom of the anion polymerization initiator. There is a base.
As the Lewis base (i-2), a structural unit derived from 1,3,7-octatriene and a structural unit derived from a conjugated diene other than 1,3,7-octatriene, particularly from the viewpoint of controlling the polymerization reaction. From the viewpoint of controlling the bonding units in 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-diisopropoxyethane, 2,2-di (tetrahydrofuryl) propane, N, N, N ', N'-Tetramethylethylenediamine (TMEDA) and N, N, N', N'-tetraethylethylenediamine are preferred.

When the Lewis base (i-2) is used, a Lewis base having monodentate coordination with respect to the metal atom of the anionic polymerization initiator and a polydentate coordination with respect to the metal atom of the anion polymerization initiator (for example, There is a difference in the preferred amount of use between Lewis bases having bidentate coordination). The Lewis base (i-2) has two or more atoms having a lone pair. When attention is paid to two atoms having the lone pair, the shortest bridge carbon number connecting them is 1 one is a _{(e.g., -O-CH 2 -O -,} > N-CH 2 -N < , etc.), or a three or more _{(e.g., -O-C 3 H 6 -O} -,> N- In the case of C ₄ H ₈ —N <, —O—C ₃ H ₆ —N <, etc.), each atom tends to have monodentate coordination. On the other hand, also when focusing on one atom 2 having an unshared electron pair, the shortest cross-linking carbon atoms connecting them is two _{(e.g., -O-C 2 H 4 -O} -,> N-C _{When 2} H ₄ -N <or the like), two atoms having these lone pairs tend to be polydentate (bidentate) with respect to one metal atom of the anionic polymerization initiator.

When the Lewis base (i-2) is a Lewis base having a monodentate coordination property, an atom having an unshared electron pair in the Lewis base (i-2) and a metal atom of a polymerization initiator used in the anionic polymerization are used. The molar ratio (atom having an unshared electron pair / metal atom of the polymerization initiator) is preferably 0.01 to 1,000, more preferably 0.1 to 500, and more preferably 2 to 300. Is more preferably, 2 to 100 is particularly preferable, and 2 to 50 is most preferable. Within this range, in particular, the ratio of the content of 3,4-linking unit to the content of 1,2-linking unit in the structural unit derived from 1,3,7-octatriene (3,4-linking unit) / 1,2-bonded unit) falls within the above preferred range. Also, it is easy to achieve a high conversion of 1,3,7-octatriene in a short time.
On the other hand, when the Lewis base (i-2) is a Lewis base having polydentate coordination (bidentate coordination), the atom having an unshared electron pair in the Lewis base (i-2) and the anionic polymerization The molar ratio to the metal atom of the polymerization initiator (atom having an unshared electron pair / metal atom of the polymerization initiator) is preferably 0.01 to 50, and more preferably 0.1 to 10. Preferably, it is more preferably 0.1 to 5, and particularly preferably 0.3 to 4. Within this range, in particular, the ratio of the content of 3,4-linking unit to the content of 1,2-linking unit in the structural unit derived from 1,3,7-octatriene (3,4-linking unit) / 1,2-bonded unit) falls within the above preferred range. Also, it is easy to achieve a high conversion of 1,3,7-octatriene in a short time.
In the case of a Lewis base having both monodentate coordination and polydentate coordination (bidentate coordination), an atom having a monodentate covalent electron pair and a polydentate coordination (bidentate coordination) are used. It is preferable to pay attention to each combination of two or more atoms having an unshared electron pair having the property (1), and determine the usage amount of the Lewis base with reference to the above description.

(solvent)
The method for producing the polymer (C) can be carried out in the absence of a solvent, but is preferably carried out in the presence of a solvent for the purpose of efficiently removing heat of polymerization.
The solvent is not particularly limited as long as it does not substantially react with the anionic polymerization initiator and the growth terminal anion, but the polymerization time, the structural unit derived from 1,3,7-octatriene and 1,1 From the viewpoint of precisely controlling the binding unit in the structural unit derived from a conjugated diene other than 3,7-octatriene with the Lewis base, a hydrocarbon solvent is preferred.
Examples of the hydrocarbon solvent include isopentane (27.9 ° C .; boiling point at 1 atm; the same applies hereinafter), pentane (36.1 ° C.), cyclopentane (49.3 ° C.), and hexane (68 0.7 ° C), cyclohexane (80.7 ° C), heptane (98.4 ° C), isoheptane (90 ° C), isooctane (99 ° C), 2,2,4-trimethylpentane (99 ° C), methylcyclohexane (101 ° C) .1 ° C), cycloheptane (118.1 ° C), octane (125.7 ° C), ethylcyclohexane (132 ° C), methylcycloheptane (135.8 ° C), nonane (150.8 ° C), decane (174) Saturated aliphatic hydrocarbons such as toluene (110.6 ° C), ethylbenzene (136.2 ° C), p-xylene (138.4 ° C), and m-xylene (1 9.1 ° C.), o-xylene (144.4 ° C.), propylbenzene (159.2 ° C.), and aromatic hydrocarbons such as butyl benzene (183.4 ° C.).
It is preferable to use a solvent having a boiling point lower than 1,3,7-octatriene (boiling point: 125.5 ° C.), which is one of the raw material monomers, because the heat of polymerization can be efficiently removed by reflux condensation cooling of the solvent. From this viewpoint, as the solvent, isopentane (27.9 ° C), pentane (36.1 ° C), cyclopentane (49.3 ° C), hexane (68.7 ° C), cyclohexane (80.7 ° C), heptane (98.4 ° C), isoheptane (90 ° C), isooctane (99 ° C), 2,2,4-trimethylpentane (99 ° C), methylcyclohexane (101.1 ° C), cycloheptane (118.1 ° C), Toluene (110.6 ° C.) is preferred. From the same viewpoint, cyclohexane and n-hexane are more preferable.
One type of solvent may be used, or two or more types may be used in combination.

The amount of the solvent used is not particularly limited, but the solid content concentration of the reaction solution after completion of the anionic polymerization is preferably 10 to 80% by mass, more preferably 10 to 70% by mass, still more preferably 15 to 65% by mass, particularly preferably Preferably, it is adjusted to be 15 to 55% by mass. Further, it is preferable to adjust the concentration of the living anion polymer in the reaction system to be 5% by mass or more, and it is more preferable to adjust the concentration of the living anion polymer to be 10 to 80% by mass. When the solvent is used in such an amount, the removal of the heat of polymerization can be achieved at a level suitable for industrial production, so that the polymerization time can be easily reduced and the high conversion of 1,3,7-octatriene can be reduced. Easy to achieve. Further, if the solvent is used in such an amount, the molecular weight distribution can be easily narrowed.
In addition, from the viewpoint of simplifying the solvent removal step, it is also possible to adjust the solid content of the reaction solution after the anionic polymerization to be 35 to 80% by mass, and to be 50 to 70% by mass. It is also possible to adjust as follows.

(Reactor)
The type of the reactor is not particularly limited, and a completely mixed reactor, a tubular reactor, and a reactor in which two or more reactors are connected in series or in parallel can be used. From the viewpoint of producing a polymer having a high solution viscosity and a narrow molecular weight distribution (Mw / Mn), it is preferable to use a complete mixing type reactor. There is no particular limitation on the stirring blade of the reactor, but examples include a max blend blade, a full zone blade, a paddle blade, a propeller blade, a turbine blade, a fan turbine blade, a faudler blade, a blue margin blade, and the like. A combination of the above may be used. When the viscosity of the obtained polymer solution is high, it is preferable to use a max blend blade or a full zone blade from the viewpoint of narrowing the molecular weight distribution (Mw / Mn) and promoting heat removal from the jacket.
The stirring method may be upper stirring or lower stirring.

  The polymerization method is not particularly limited, and it may be carried out in any of a batch system, a semi-batch system, and a continuous system. The complete mixing type reactor may have a jacket outside for the purpose of heating and cooling the solution inside the reactor, and its structure is not particularly limited, and a known type can be used. Further, a cooling baffle or a cooling coil may be provided inside the reactor for the purpose of increasing the cooling heat transfer as desired. Further, a reflux condenser may be provided directly or indirectly in the gas phase portion. From the viewpoint of controlling the amount of polymerization heat removed, the reactor may be pressurized using an inert gas, or may be depressurized so as to be at or below atmospheric pressure. When the internal pressure of the reactor is reduced to the atmospheric pressure or less, a pump for exhausting the inert gas may be provided via a reflux condenser. The structure of the reflux condenser is not particularly limited, but it is preferable to use a multi-tube reflux condenser. The reflux condenser may connect a plurality of reflux condensers in series or in parallel, and may pass a different refrigerant to each reflux condenser. The temperature of the refrigerant passing through the reflux condenser is not particularly limited as long as it is in a range from a temperature at which the refluxing solvent does not freeze to a temperature of the reaction solution, but is preferably -20 to 50 ° C, more preferably 5 to 30 ° C. If a large refrigerator is not required, it is economical.

(Polymerization temperature)
The polymerization temperature is not particularly limited, but the polymerization is preferably performed at a temperature higher than the freezing point of the raw materials and the solvent to be used and at a temperature lower than the temperature at which the raw materials and the solvent to be used are not thermally decomposed. Preferably it is -50-200 degreeC, More preferably, it is -20-120 degreeC, More preferably, it is 15-100 degreeC. When the polymerization temperature is within the above range, in particular, the ratio of the content of 3,4-linkage unit to the content of 1,2-linkage unit in the structural unit derived from 1,3,7-octatriene (3,3 (4-linkage unit / 1,2-linkage unit) is in the above preferred range. In addition, while maintaining the shortening of the polymerization time and maintaining the high conversion of 1,3,7-octatriene, the mechanical properties by suppressing the production of low molecular weight polymer due to the partial thermal degradation of the growth terminal anion are improved. An excellent polymer can be produced.

(Polymerization pressure)
Polymerization can be suitably carried out as long as a substance that reacts with the growth terminal anion and inhibits the polymerization reaction, for example, the entry of air containing oxygen and water is suppressed.
When using a solvent having a boiling point lower than the polymerization temperature, the temperature may be controlled by controlling the pressure with an inert gas to control the amount of solvent vapor generated, and a solvent having a boiling point higher than the polymerization temperature may be used. When is used, the temperature may be controlled by reducing the pressure in the reaction system using an exhaust pump and controlling the amount of solvent vapor generated.
The polymerization pressure is not particularly limited, but if it is 0.01 to 10 MPaG, more preferably 0.1 to 1 MPaG, not only can the amount of inert gas used be reduced, but also a high pressure-resistant reactor and inert gas can be removed from the system. Polymerization can be carried out economically and advantageously since a pump for exhausting air is not required.

(Polymerization time)
The polymerization time is not particularly limited, but is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours, to suppress the production of a low molecular weight polymer due to partial thermal deterioration of the growth terminal anion. Further, it is easy to produce a polymer having excellent mechanical properties.

(Polymerization terminator and coupling agent)
In the method for producing the polymer (C), the polymerization reaction is preferably stopped by adding a polymerization terminator or a coupling agent to the reaction system. Examples of the polymerization terminator or the coupling agent include a hydrogen molecule; an oxygen molecule; water; methanol, ethanol, propanol, isopropanol, butanol, heptanol, cyclohexanol, phenol, benzyl alcohol, o-cresol, m-cresol, p- Alcohols such as cresol, ethylene glycol, propylene glycol, butanediol, glycerin, catechol; methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, ethyl iodide, butyl chloride, butyl bromide, butyl iodide , Benzyl chloride, benzyl bromide, benzyl iodide, trimethylsilyl fluoride, trimethylsilyl chloride, trimethylsilyl bromide, trimethylsilyl iodide, triethylsilyl fluoride, triethylsilyl chloride, triethylsilyl bromide, iodine Halogen compounds such as triethylsilyl fluoride, tributylsilyl fluoride, tributylsilyl chloride, tributylsilyl bromide, tributylsilyl iodide, triphenylsilyl fluoride, triphenylsilyl chloride, triphenylsilyl bromide and triphenylsilyl iodide; 2 Ketones such as -heptanone, 4-methyl-2-pentanone, cyclopentanone, 2-hexanone, 2-pentanone, cyclohexanone, 3-pentanone, acetophenone, 2-butanone and acetone; methyl acetate, ethyl acetate and butyl acetate; Esters: Epoxy compounds such as ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, styrene oxide and cyclohexene oxide; methyldichlorosilane, ethyldichlorosilane, propyldichlorosila , Butyldichlorosilane, pentyldichlorosilane, hexyldichlorosilane, heptyldichlorosilane, octyldichlorosilane, nonyldichlorosilane, decyldichlorosilane, phenyldichlorosilane, dimethylchlorosilane, diethylchlorosilane, dipropylchlorosilane, dibutylchlorosilane, dipentylchlorosilane, dihexyl Chlorosilane, diheptylchlorosilane, dioctylchlorosilane, dinonylchlorosilane, didecylchlorosilane, methylpropylchlorosilane, methylhexylchlorosilane, methylphenylchlorosilane, diphenylchlorosilane, dimethylmethoxysilane, dimethylethoxysilane, dimethylpropoxysilane, dimethylbutoxysilane, dimethylphenoxy Silane, dimethylbenzyl Oxysilane, diethylmethoxysilane, diethylethoxysilane, diethylpropoxysilane, diethylbutoxysilane, diethylphenoxysilane, diethylbenzyloxysilane, dipropylmethoxysilane, dipropylethoxysilane, dipropylpropoxysilane, dipropylbutoxysilane, dipropylphenoxy Silane, dipropylbenzyloxysilane, dibutylmethoxysilane, dibutylethoxysilane, dibutylpropoxysilane, dibutylbutoxysilane, dibutylphenoxysilane, dibutylbenzyloxysilane, diphenylmethoxysilane, diphenylethoxysilane, diphenylpropoxysilane, diphenylbutoxysilane, diphenyl Phenoxysilane, diphenylbenzyloxysilane, dimethylsila , Diethylsilane, dipropylsilane, dibutylsilane, diphenylsilane, diphenylmethylsilane, diphenylethylsilane, diphenylpropylsilane, diphenylbutylsilane, trimethylsilane, triethylsilane, tripropylsilane, tributylsilane, triphenylsilane, methylsilane, ethylsilane , Propylsilane, butylsilane, phenylsilane, methyldiacetoxysilane, polymethylhydrosiloxane, polyethylhydrosiloxane, polypropylhydrosiloxane, polybutylhydrosiloxane, polypentylhydrosiloxane, polyhexylhydrosiloxane, polyheptylhydrosiloxane, poly Octylhydrosiloxane, polynonylhydrosiloxane, polydecylhydrosiloxane, polyphenyl Drosiloxane, 1,1,3,3-tetramethyldisiloxane, methylhydrocyclosiloxane, ethylhydrocyclosiloxane, propylhydrocyclosiloxane, butylhydrocyclosiloxane, phenylhydrocyclosiloxane, 1,1,3,3-tetra Methyldisilazane, 1,1,3,3-tetraethyldisilazane, 1,1,3,3-tetrapropyldisilazane, 1,1,3,3-tetrabutyldisilazane, 1,1,3,3- And silyl hydride compounds such as tetraphenyldisilazane.
One type of polymerization terminator or coupling agent may be used, or two or more types may be used in combination.
The polymerization terminator or the coupling agent may be used after being diluted with a solvent that can be used for the polymerization reaction. There is no particular limitation on the amount of the polymerization terminator or the coupling agent to be used, but it is preferable from the viewpoint of solvent recovery and reuse that the polymerization terminator or the coupling agent is not excessive with respect to the growth terminal anion, and When hydrogenating a polymer, it is also preferable in that the amount of the hydrogenation catalyst used can be reduced.

  The conversion of 1,3,7-octatriene determined by gas chromatography after completion of anionic polymerization is preferably 30.0% or more, more preferably 40.0% or more, and more preferably 50.0%. More preferably, it is the above.

(Hydrogenation reaction)
From the viewpoints of heat resistance, oxidation resistance, weather resistance, ozone resistance and the like of the polymer, the carbon-carbon double bond of the polymer may be hydrogenated. Usually, a polymer solution obtained by terminating the polymerization in the method for producing a polymer or a polymer solution diluted with the solvent, if necessary, to a polymer solution by adding a hydrogenation catalyst and reacting with hydrogen. Hydride can be produced.
Examples of the hydrogenation catalyst include Raney nickel; a heterogeneous catalyst in which a metal such as Pt, Pd, Ru, Rh, and Ni is supported on a simple substance such as activated carbon, alumina, and diatomaceous earth; a transition metal compound and an alkylaluminum compound; Ziegler-type catalysts comprising a combination with a compound or the like; metallocene catalysts and the like.

  The temperature of the hydrogenation reaction is preferably −20 to 250 ° C., which is equal to or higher than the freezing point of the solvent and equal to or lower than the thermal decomposition temperature of the polymer, and is preferably 30 to 150 ° C. from the viewpoint of industrially producing a hydride of the polymer. C. is more preferable. If the temperature is 30 ° C. or higher, the hydrogenation reaction proceeds, and if the temperature is 150 ° C. or lower, the hydrogenation reaction can be carried out with a small amount of the hydrogenation catalyst even if the thermal decomposition of the hydrogenation catalyst occurs simultaneously. From the viewpoint of reducing the amount of the hydrogenation catalyst used, 60 to 100C is more preferable.

Hydrogen can be used in gaseous form, and the pressure is not particularly limited as long as it is equal to or higher than normal pressure, but is preferably 0.1 to 20 MPaG from the viewpoint of industrially producing a polymer hydride. When the pressure is 20 MPaG or less, the hydrogenation reaction can be performed with a small amount of the hydrogenation catalyst even if the hydrogenolysis of the hydrogenation catalyst occurs simultaneously. From the viewpoint of reducing the amount of the hydrogenation catalyst used, 0.5 to 10 MPaG is more preferable.
The time required for the hydrogenation reaction can be appropriately selected depending on conditions, but is preferably in the range of 10 minutes to 24 hours from the start of coexistence with the catalyst from the viewpoint of industrially producing a polymer hydride.
After completion of the hydrogenation reaction, the reaction mixture may be diluted or concentrated with the above-described solvent, if necessary, and then washed with a basic aqueous solution or an acidic aqueous solution to remove the hydrogenation catalyst.

  The polymer solution obtained after the polymerization reaction or the polymer solution obtained after the hydrogenation reaction may be supplied to an extruder after performing a concentration operation to isolate the polymer, or may be brought into contact with steam to remove a solvent or the like. The polymer may be isolated by removing the polymer, or the polymer may be isolated by bringing the polymer into contact with a heated inert gas to remove a solvent or the like.

<Vulcanization accelerator>
The rubber composition of the present invention may contain a vulcanization accelerator. Examples of the vulcanization accelerator 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 vulcanization accelerating aid is contained, its content is preferably 0.1 to 15 parts by mass, more preferably 1 to 10 parts by mass, based on 100 parts by mass of the rubber component (A).

<Vulcanizing agent>
It is preferable to add a vulcanizing agent to the rubber composition of the present invention. Examples of the vulcanizing agent include sulfur and a sulfur compound. 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 still more preferably 0.8 to 5 parts by mass with respect to 100 parts by mass of the rubber component (A). Department.

<Vulcanization accelerator>
The rubber composition of the present invention may contain a vulcanization accelerator. As the vulcanization accelerator, for example, guanidine compounds, sulfenamide compounds, thiazole compounds, thiuram compounds, thiourea compounds, dithiocarbamic acid compounds, aldehyde-amine compounds or aldehyde-ammonia compounds, imidazoline compounds And xanthate compounds. These may be used alone or in combination of two or more. When the vulcanization accelerator is contained, the content is preferably 0.1 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the rubber component (A).

<Silane coupling agent>
When the rubber composition of the present invention contains silica as the filler (B), it 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 the sulfide compound 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-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-trimethoxysilylethyl-N, -Dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, etc. No.
Examples of the mercapto compound include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane.
Examples of the vinyl compound include vinyl triethoxy silane and vinyl trimethoxy silane.
Examples of the amino compound include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, and 3- (2-aminoethyl) aminopropyltrimethoxy Examples include silane.
Examples of the glycidoxy-based compound include γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, and the like. No.
Examples of the nitro compound include 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, and the like.
Examples of the chloro compound include 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane and the like.
One of these silane coupling agents may be used, or two or more thereof may be used in combination. Among them, from the viewpoint of a large reinforcing effect, a sulfur-containing silane coupling agent such as a sulfide compound or a mercapto compound is preferable, and bis (3-triethoxysilylpropyl) disulfide, bis (3-triethoxysilylpropyl) tetra Sulfide and 3-mercaptopropyltrimethoxysilane are more preferred.

  The content of the silane coupling agent with respect to 100 parts by mass of silica is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, and still more preferably 1 to 15 parts by mass. When the content of the silane coupling agent is within the above range, dispersibility, reinforcing property, and abrasion resistance are improved.

<Other ingredients>
The rubber composition of the present invention aims at improving processability, fluidity, etc. within a range not to impair the effects of the present invention, and if necessary, silicone oil, aroma oil, TDAE (Treated Distilled Aromatic Extracts), MES ( Mild Extracted Solvates), RAE (Residual Aromatic Extracts), process oils such as paraffin oil and naphthenic oil, aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, C9 resins, rosin resins, cumarone and indene resins, phenol Resin components such as resin, low-molecular-weight polybutadiene, low-molecular-weight polyisoprene, low-molecular-weight styrene-butadiene copolymer, low-molecular-weight styrene-isoprene copolymer, and other liquid polymers, even if unmodified polymers are contained as softeners Good. In addition, 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 from 500 to 100,000 from the viewpoint of processability. When the rubber composition of the present invention contains the process oil, the resin component or the liquid polymer, and the unmodified polymer as a softening agent, the content is from 50 parts by mass to 100 parts by mass of the rubber component (A). Preferably, it is small.

The rubber composition of the present invention, within a range not to impair the effects of the present invention, for the purpose of improving weather resistance, heat resistance, oxidation resistance, etc., as necessary, an antioxidant, an antioxidant, a wax, a lubricant, Light stabilizers, anti-scorch agents, processing aids, coloring agents such as pigments and dyes, flame retardants, antistatic agents, matting agents, antiblocking agents, ultraviolet absorbers, release agents, foaming agents, antibacterial agents, One or more kinds of additives such as a mold agent and a fragrance may be contained.
Examples of the anti-aging agent include amine-ketone compounds, imidazole compounds, amine compounds, phenol compounds, sulfur compounds, and phosphorus compounds.
Examples of the antioxidant include a hindered phenol compound, a phosphorus compound, a lactone compound, a hydroxyl compound and the like.

  The rubber composition of the present invention may be vulcanized using the vulcanizing agent, or may be crosslinked by adding a crosslinking agent. Examples of the crosslinking agent include oxygen, organic peroxides, phenol resins and amino resins, quinone and quinone dioxime derivatives, halogen compounds, aldehyde compounds, alcohol compounds, epoxy compounds, metal halides and organometal halides, and silane compounds. And the like. These may be used alone or in combination of two or more. The content of the crosslinking agent is preferably from 0.1 to 10 parts by mass based on 100 parts by mass of the rubber component (A).

  The method for producing the rubber composition of the present invention is not particularly limited, and the components described above may be uniformly mixed. Examples of the method of uniformly mixing include, for example, a tangential or intermeshing type internal mixer such as a kneader ruder, a Brabender, a Banbury mixer, and an internal mixer, a single screw extruder, a twin screw extruder, a mixing roll, a roller, and the like. The reaction can be usually performed in a temperature range of 70 to 270 ° C.

  The rubber composition of the present invention can be used as a vulcanized rubber by vulcanizing. There are no particular restrictions on the vulcanization conditions and methods, but it is preferable to use a vulcanization mold under the pressure and heating conditions of a vulcanization temperature of 120 to 200 ° C. and a vulcanization pressure of 0.5 to 2.0 MPaG.

[tire]
The tire of the present invention uses at least a part of the rubber composition of the present invention. Therefore, it has high hardness and excellent steering stability.

  Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

  In each of the following examples, the conversion of 1,3,7-octatriene and isoprene, polymer yield, weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn), and 1,3,7-octatriene Were determined in accordance with the following measurement method.

(1) Method of measuring conversion ratio 5.00 g of ethylene glycol dimethyl ether was added to 5.00 g of the polymerization termination solution obtained after the completion of the polymerization reaction, and the mixture was analyzed by gas chromatography under the following measurement conditions.
The “area ratio of 1,3,7-octatriene and ethylene glycol dimethyl ether (0 hours) at the start of the polymerization reaction (S1)” and “the unreacted 1,3,7-octatriene and ethylene glycol dimethyl ether after the polymerization reaction were completed From the area ratio of (S2) ", the conversion (%) of 1,3,7-octatriene was calculated based on the following formula 1.
In addition, from “area ratio of isoprene and ethylene glycol dimethyl ether before reaction as 0 hour of the start of polymerization reaction (S3)” and “area ratio of unreacted isoprene and ethylene glycol dimethyl ether after reaction (S4)”, Based on this, the conversion of isoprene (%) was calculated.
<Gas chromatography measurement conditions>
Equipment: “GC-14B” manufactured by Shimadzu Corporation
Column: “Rxi-5ms” manufactured by Restek Corporation (inner diameter 0.25 mm, length 30 m, film thickness 0.25 μm)
Carrier gas: Helium (140.0 kPaG) was passed at a flow rate of 1.50 mL / min.
Sample injection volume: 0.1 μL of the drug solution was injected at a split ratio of 50/1.
Detector: FID
Detector temperature: 280 ° C
Evaporation chamber temperature: 280 ° C
Temperature rising conditions: After holding at 40 ° C. for 10 minutes, the temperature was raised to 250 ° C. at 20 ° C./minute, and then held for 5 minutes.

(2) Method for Measuring Yield of Polymer Based on the charged amount of the raw material monomers, the yield of the obtained polymer was determined based on the following Expression 3.

(2) Method for measuring weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) A uniform solution was prepared by adding 60.0 g of tetrahydrofuran to 0.10 g of the obtained polymer, and the solution was subjected to the following measurement conditions. Was used to determine the weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of standard polystyrene, and the molecular weight distribution (Mw / Mn) was calculated.
<Measurement conditions for gel permeation chromatography>
Apparatus: "HLC-8320GPC EcoSEC" manufactured by Tosoh Corporation
Column: Two TSKgel SuperMultipore HZ-M (inner diameter 4.6 mm, length 150 mm) manufactured by Tosoh Corporation were used in series.
Eluent: tetrahydrofuran was passed at a flow rate of 0.35 mL / min.
Sample injection volume: 10 μL
Detector: RI
Detector temperature: 40 ° C

(3) Binding unit 1.00 g of deuterated chloroform was added to 150 mg of the obtained polymer to prepare a uniform solution, and this solution was subjected to ¹³ C-NMR measurement under the following measurement conditions.
< ^13C -NMR measurement conditions>
Equipment: "JNM-LA500" manufactured by JEOL Ltd.
Reference substance: Tetramethylsilane Measurement temperature: 25 ° C
Number of accumulation: 15,000 times

As a result of the ¹³ C-NMR measurement, the “peak attributable to the carbon atom at the 7-position of the 1,2-bond unit” of 1,3,7-octatriene was changed to δ138.1 to 138.6 ppm and “1,4- The peak attributable to the 7-position carbon atom of the bonding unit and the 7-position carbon atom of the 3,4-bonding unit is δ138.8 to 139.4 ppm, and the “peak attributable to the 2-position carbon atom of the 3,4-bonding unit”. Was observed at δ 140.9 to 141.6 ppm. The peak area corresponding to the carbon atom at the 7-position of the 1,4-bond unit was calculated by subtracting the peak area of δ140.9 to 141.6 ppm from the peak area of δ138.8 to 139.4 ppm. Assigned peak area).
The ratios of 1,2-linkage units, 1,4-linkage units and 3,4-linkage units derived from 1,3,7-octatriene contained in the polymer were determined from the following formulas 4 to 6, respectively.

Further, regarding the polymer (C-9) obtained in Production Example 9 described later, the “peak attributed to the 3-position carbon atom of the 1,2-bonded unit” of isoprene was set to δ140.5 to 141.0 ppm, and “ The “peak attributable to the 3-position carbon atom of the 1,4-bond unit” is δ122.0 to 126.9 ppm, and the “peak attributable to the 1-carbon atom of the 3,4-bond unit” is δ110.2 to 112. Observed at 2 ppm.
The proportions of 1,2-bonded units, 1,4-bonded units and 3,4-bonded units derived from isoprene contained in the copolymer were determined from the following mathematical expressions 4 to 6, respectively.

(4) The ratio of the content of 3,4-linkage unit to the content of 1,2-linkage unit contained in the structural unit derived from 1,3,7-octatriene (3,4-linkage unit / 1 , 2-bonded unit)
From the ratio of the 1,2-linkage unit and the ratio of the 3,4-linkage unit contained in the structural unit derived from 1,3,7-octatriene obtained in the above (3), the ratio (3,4- (Binding unit / 1,2-binding unit) was calculated.

(Production Example 1: Production of Polymer (C-1) (Homopolymer of 1,3,7-octatriene))
After replacing the inside of a 1-L SUS316 (registered trademark) autoclave equipped with a thermometer, an electric heater, an electromagnetic induction stirrer, a chemical solution charging port, and a sampling port with argon, 232.0 g of cyclohexane was charged as a solvent. Subsequently, 60.89 g (0.563 mol) of 1,3,7-octatriene was charged. Thereafter, the internal pressure was adjusted to 0.3 MPaG with argon, and the temperature was raised to 50 ° C. over 30 minutes while stirring at 250 rpm. Under an argon stream, 3.76 g (52.12 mmol) of tetrahydrofuran (THF) was charged, followed by 8.27 g (10.42 mmol as sec-butyllithium) of a cyclohexane solution containing 1.26 mmol / g of sec-butyllithium. After that, the internal pressure was adjusted to 0.3 MPaG with argon. The reaction was performed for 1 hour while controlling the liquid temperature to be 50 ° C., with this time being 0 hour from the start of the polymerization reaction.
Thereafter, 4.586 g (11.465 mmol as ethanol) of a cyclohexane solution containing 2.5 mmol / g of ethanol was added to terminate the polymerization reaction.
Next, the whole amount of the obtained polymerization terminating solution was transferred to a 1-L eggplant-shaped flask, and most of the solvent was distilled off while heating at 40 ° C. under 100 kPaA using a rotary evaporator. Further, the eggplant flask was transferred to a reduced-pressure drier and dried for 12 hours while heating at 25 ° C. under 0.1 kPaA to obtain 57.85 g of a liquid polymer (C-1). The obtained polymer (C-1) was evaluated using the measurement method described above. Table 1 shows the results.

(Production Examples 2 to 8: Production of Polymers (C-2) to (C-8) (Homopolymer of 1,3,7-octatriene))
Polymerization reaction was carried out in the same manner as in Production Example 1 except that the reagents, their amounts used, and the reaction conditions were changed as shown in Table 1, to obtain polymers (C-2) to (C-8). Was. The obtained polymers (C-2) to (C-8) were evaluated using the above measurement method. Table 1 shows the results. In addition, in Table 1, the blank column represents no formulation.

(Production Example 9: Production of polymer (C-9) (1,3,7-octatriene-isoprene copolymer))
After replacing the inside of a 1-L SUS316 (registered trademark) autoclave equipped with a thermometer, an electric heater, an electromagnetic induction stirrer, a chemical solution charging port, and a sampling port with argon, 232.0 g of cyclohexane was charged as a solvent. Subsequently, the internal pressure was adjusted to 0.3 MPaG with argon, and the temperature was raised to 50 ° C. over 30 minutes while stirring at 250 rpm. Under an argon gas flow, 1.43 g (19.78 mmol) of tetrahydrofuran (THF) was charged, followed by 3.14 g (3.96 mmol as sec-butyllithium) of a cyclohexane solution containing 1.26 mmol / g of sec-butyllithium. After that, the internal pressure was adjusted to 0.3 MPaG with argon.
On the other hand, 87.72 g (0.811 mol) of 1,3,7-octatriene and 70.30 g (1.03 mol) of isoprene are mixed and then supplied to the autoclave containing sec-butyllithium over 0.5 hours. did. The reaction was started for 2 hours while the liquid temperature was controlled to be 50 ° C., with the time of the start of the charging being 0 hour from the start of the polymerization reaction.
Thereafter, 1.740 g (4.350 mmol as ethanol) of a cyclohexane solution containing 2.5 mmol / g of ethanol was added to stop the polymerization reaction.
Next, the whole amount of the obtained polymerization terminating solution was transferred to a 1-L eggplant-shaped flask, and most of the solvent was distilled off while heating at 40 ° C. under 100 kPaA using a rotary evaporator. Further, the eggplant flask was transferred to a reduced-pressure drier and dried for 12 hours while heating at 25 ° C. under 0.1 kPaA to obtain 146.96 g of a liquid copolymer (polymer (C-9)). The obtained polymer (C-9) was evaluated using the measurement method described above. Table 1 shows the results.

(Comparative Production Examples 1 and 2: Production of Polymers (I) and (II) (Homopolymer of 1,3,7-octatriene))
Polymerization reaction was carried out in the same manner as in Production Example 1 except that the reagents, their amounts used, and the reaction conditions were changed as shown in Table 1, to obtain polymers (I) and (II). The obtained polymers (I) and (II) were evaluated using the measurement method described above. Table 1 shows the results.

In Production Examples 1-3, 5-7, and 9 produced using tetrahydrofuran (THF) as the Lewis base (i-1), the content of the 3,4-linkage unit relative to the content of the 1,2-linkage unit Of 1,3,7-octatriene homopolymer and 1,3,7-octatriene-isoprene copolymer having a ratio of 0.055 to 0.128 were obtained.
In Production Examples 4 and 8, which were produced using N, N, N ', N'-tetramethylethylenediamine (TMEDA) as the Lewis base (i-2), 3,4 based on the content of 1,2-linkage units. -A 1,3,7-octatriene homopolymer having a binding unit content ratio of 0.313 to 0.365 was obtained.
In Comparative Production Examples 1 and 2 in which no Lewis base was used, 1,3,7-octatriene homopolymer containing no 3,4-linkage unit was obtained.

The components used in the examples and comparative examples are as follows.
[Rubber component (A)]
・ Natural rubber: "STR20" Thai natural rubber [Filler (B)]
-Carbon black: "Dia Black H" manufactured by Mitsubishi Chemical Corporation, average particle size 30 nm
[Polymer (C)]
-Polymers (C-1) to (C-8): 1,3,7-octatriene homopolymer obtained in Production Examples 1 to 8-Polymer (C-9): obtained in Production Example 9 1,3,7-octatriene-isoprene copolymer [Polymer other than polymer (C)]
Polymers (I) and (II): 1,3,7-octatriene homopolymer obtained in Comparative Production Examples 1 and 2 [Other components]
-Anti-aging agent: "Nocrack 6C" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.-Vulcanizing agent: sulfur (fine powder sulfur 200 mesh), manufactured by Tsurumi Chemical Industry Co., Ltd.-Vulcanization accelerator: "Suncellar NS-G" Sanshin Vulcanization accelerator (1): Zinc flower, "Zinc oxide" manufactured by Sakai Chemical Industry Co., Ltd. Vulcanization accelerator (2): Stearic acid, "Lunac S-20" Kao Corporation Made

(Example 1)
According to the compounding ratio (parts by mass) described in Table 2, the rubber component (A), the filler (B), the polymer (C), the antioxidant, and the vulcanization accelerating assistant were each used as a plastic lab station manufactured by Brabender. After being charged into W350E and kneaded for 20 minutes while controlling the resin temperature to 145 ° C., it was taken out of the mixer and cooled to room temperature (25 ° C.). Next, the mixture was put into a mixing roll, a vulcanizing agent and a vulcanization accelerator were added, and the mixture was kneaded at 40 ° C. for 4 minutes to obtain about 240 g of a rubber composition. The obtained rubber composition was press-molded (145 ° C., 14 minutes) to prepare a vulcanized rubber sheet (2 mm thick), and the hardness (steering stability) and tan δ [maximum number of peaks (phase Solubility)] was evaluated. Table 2 shows the results. In addition, in Table 2, the blank column shows no compounding.

(Examples 2 to 9 and Comparative Examples 1 and 2)
A rubber composition was obtained in the same manner as in Example 1 except that the types and amounts were changed to those shown in Table 2. The obtained rubber composition was press-molded (145 ° C., 14 minutes) to prepare a vulcanized rubber sheet (2 mm thick), and the hardness (steering stability) and tan δ [maximum number of peaks (phase Solubility)] was evaluated. Table 2 shows the results.
The measuring method of each evaluation is as follows.

(5) Hardness (steering stability)
Using the sheets of the rubber compositions produced in the examples and comparative examples, the hardness was measured with a type A hardness meter in accordance with JIS K6253 (2012), and used as an index of flexibility. When the numerical value is smaller than 50, the tire is greatly deformed when the composition is used for a tire, so that steering stability is deteriorated.

(6) tan δ [maximum number of peaks (compatibility)]
A test piece having a length of 40 mm and a width of 7 mm was cut out from a sheet of the rubber composition prepared in each of Examples and Comparative Examples, and was measured at a measurement temperature of -100 to 30 ° C., a frequency of 10 Hz and a static viscoelasticity using a GABO dynamic viscoelasticity measuring apparatus. The tan δ was measured under the conditions of a dynamic strain of 0.5% and a dynamic strain of 0.1%, and the maximum number of tan δ obtained was obtained.

  The rubber compositions of Examples 1 to 9 containing the polymer (C) containing a structural unit derived from 1,3,7-octatriene containing a 3,4-linkage unit contain the polymer (C). It can be seen that the hardness of the molded product is higher than that of the rubber compositions of Comparative Examples 1 and 2. Further, since the maximum peak of tan δ is single, it can be said that the rubber component (A) and the polymer (C) are in a state of being compatible at the molecular level.

(7) The value of tan δ (rolling resistance performance)
A test piece having a length of 40 mm and a width of 7 mm was cut out from the rubber composition sheets prepared in Examples 5 to 8 and Comparative Example 1, and measured using a GABO dynamic viscoelasticity measuring device at a measurement temperature of 60 ° C. and a frequency of 10 Hz. The value of tan δ was measured under the conditions of a static strain of 10% and a dynamic strain of 2%.
Since tan δ at 60 ° C. and the rolling performance of the tire show a high correlation, this value was used as an index of the rolling resistance. The numerical values of Examples 5 to 8 are relative values when the value of Comparative Example 1 is set to 100. Table 3 shows the results. The smaller the value, the better the rolling resistance performance of the rubber composition.

  It can be seen that the rubber compositions of Examples 5 to 8 in which the Mw of the polymer (C) is 50,000 or more further improve the rolling resistance performance.

Claims (6)

A rubber component (A) composed of at least one of synthetic rubber and natural rubber, a filler (B), and a polymer (C) containing a structural unit derived from 1,3,7-octatriene,
A rubber composition wherein the structural unit derived from 1,3,7-octatriene contains a 3,4-bond unit.   The structural unit derived from 1,3,7-octatriene includes a 3,4-linkage unit and a 1,2-linkage unit, and the 3,4-linkage relative to the content of the 1,2-linkage unit. The rubber composition according to claim 1, wherein the ratio of the content of the binding unit (3,4-linking unit / 1,2-linking unit) is 0.04 to 0.7.   The rubber composition according to claim 1, wherein the filler (B) is at least one of carbon black and silica.   The rubber composition according to any one of claims 1 to 3, wherein the rubber component (A) is at least one of styrene butadiene rubber and natural rubber.   The rubber composition according to any one of claims 1 to 4, wherein the polymer (C) has a weight average molecular weight (Mw) of 1,000 to 1,000,000.   A tire using at least a part of the rubber composition according to claim 1.