JP7235225B2 - Rubber composition and tire - Google Patents

Description

The present invention relates to rubber compositions and tires.

Conventionally, rubber components such as natural rubber and styrene-butadiene rubber are blended with fillers such as carbon black and crosslinked to improve mechanical strength. Widely used for various purposes. The carbon black is known to exhibit its reinforcing effect by physically or chemically adsorbing the rubber component on the particle surface. When carbon black having a small average particle size of about 5 to 100 nm and a large specific surface area is used, the interaction between the carbon black and the rubber component increases, so the mechanical strength and wear resistance of the rubber composition are improved. Improves properties. Moreover, when the rubber composition is used as a tire, the steering stability is improved because the hardness is increased.

For example, Patent Document 1 describes a rubber composition for tires containing a rubber component containing an isoprene rubber and a styrene-butadiene rubber, carbon black, and a liquid resin having a softening point of -20 to 20°C in a specific ratio. ing. Further, Patent Document 2 describes a rubber obtained by blending 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 in a predetermined ratio. A composition is described.

Further, Patent Documents 3 and 4 describe a method for polymerizing 1,3,7-octatriene.

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

According to the tires using the rubber compositions described in Patent Documents 1 and 2, although the hardness can be improved to some extent, the steering stability due to the hardness is also at a sufficiently high level. However, further improvement is desired.
Moreover, although it is described that the polymer described in Patent Document 3 is useful as a raw material for various polymer materials, adhesives, and lubricants, 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 can be used as a base material that can be converted into a useful industrial material by performing various chemical modifications utilizing its properties. It is not envisioned that the coalescence will be used as a rubber composition.

An object of the present invention is to provide a rubber composition from which a rubber molded article having high hardness and excellent steering stability can be obtained, and a tire at least partially using 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-bond unit has high hardness and steering stability. The present invention was completed by discovering that it is excellent in

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 structural units derived from 1,3,7-octatriene, A rubber composition in which the structural unit derived from 1,3,7-octatriene includes a 3,4-linkage unit.
[2] The structural unit derived from 1,3,7-octatriene includes a 3,4-bonding unit and a 1,2-bonding unit, and the 3 ,4-linkage unit content ratio (3,4-linkage unit/1,2-linkage unit) is from 0.04 to 0.7.
[3] The rubber composition according to [1] or [2] above, wherein the filler (B) is at least one of carbon black and silica.
[4] The rubber composition according to any one of [1] to [3] above, 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 [1] to [4] above, wherein the polymer (C) has a weight average molecular weight (Mw) of 1,000 to 1,000,000.
[6] A tire at least partially using the rubber composition according to any one of [1] to [5] above.

ADVANTAGE OF THE INVENTION According to this invention, the rubber composition which can obtain the rubber molding with high hardness and excellent steering stability, and the tire which used the said rubber composition for at least one part can be provided.

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

<Rubber component (A)>
Rubber comprising at least one of synthetic rubber and natural rubber is used as the rubber component (A). 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. , natural rubber and the like. Among them, SBR, butadiene rubber, isoprene rubber, and natural rubber are preferred, and SBR and natural rubber are more preferred. These rubbers may be used alone or in combination of two or more.

[Synthetic rubber]
When a synthetic rubber is used as the rubber component (A) in the present invention, SBR, butadiene rubber, isoprene rubber, butyl rubber, halogenated butyl rubber, ethylene propylene diene rubber, butadiene acrylonitrile copolymer rubber, chloroprene rubber, etc. are preferred, and among these, SBR is preferred. , isoprene rubber, and butadiene rubber are more preferred, and SBR is even more preferred.

(SBR(AI))
As the SBR, a general one used for tire applications can be used. is more preferred, and 25.4 to 50.9 mol% is even more preferred. Also, the vinyl content is preferably 0.1 to 60 mol %, more preferably 0.1 to 55 mol %.
Incidentally, the vinyl content referred to here refers to the number of monomer units having 1,2-bonds among the monomer units consisting of 1,4-bonds and 1,2-bonds derived from all butadiene contained in SBR. Represents the content. The weight average molecular weight (Mw) of SBR is preferably 100,000 to 2,500,000, more preferably 150,000 to 2,000,000, and 200,000 to 1,500,000. is more preferable. When it is within 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 molecular weights in terms of standard polystyrene obtained by gel permeation chromatography (GPC) measurement. Moreover, the molecular weight distribution (Mw/Mn) is a value calculated therefrom.
The glass transition temperature (Tg) of the SBR used in the present invention determined by differential thermal analysis is preferably in the range of -95 to 0°C, more preferably in the range of -95 to -5°C. preferable. By setting the Tg within the above range, it is possible to suppress an increase in viscosity and facilitate handling.

<<Manufacturing method of SBR>>
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 emulsion polymerization method, solution polymerization method, gas phase polymerization method and bulk polymerization method can be used, and emulsion polymerization method and solution polymerization method are particularly preferable.

(i) Emulsion polymerized styrene-butadiene rubber (E-SBR)
E-SBR can be produced by an ordinary emulsion polymerization method, for example, predetermined amounts of styrene and butadiene monomers are emulsified and dispersed in the presence of an emulsifier, and emulsion polymerization is performed with a radical polymerization initiator.
As the emulsifier, for example, a long-chain fatty acid salt or 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 usually used as the dispersion medium, and it may contain a water-soluble organic solvent such as methanol or ethanol as long as the stability during polymerization is not impaired.
Examples of radical polymerization initiators include persulfates such as ammonium persulfate and potassium persulfate, organic peroxides, and hydrogen peroxide.
A chain transfer agent can also be used to adjust the molecular weight of the resulting E-SBR. Examples of chain transfer agents include mercaptans such as tert-dodecylmercaptan and n-dodecylmercaptan; carbon tetrachloride, thioglycolic acid, diterpene, terpinolene, γ-terpinene, α-methylstyrene dimer and the like.

The emulsion polymerization temperature can be appropriately selected depending on the type of 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. Polymerization reactions can be terminated by the addition of a polymerization terminating agent.
Examples of the polymerization terminator include amine compounds such as isopropylhydroxylamine, diethylhydroxylamine and hydroxylamine; quinone compounds such as hydroquinone and benzoquinone; and sodium nitrite.
After termination of the polymerization reaction, an anti-aging agent may be added as necessary. After stopping the polymerization reaction, unreacted monomers are removed from the obtained latex if necessary, and then salts such as sodium chloride, calcium chloride and potassium chloride are used as coagulants, and if necessary nitric acid, sulfuric acid and the like are added. After the polymer is coagulated while adjusting the pH of the coagulation system to a predetermined value by adding an acid, the polymer can be recovered as crumbs by separating the dispersion solvent. E-SBR is obtained by washing the crumb with water, dehydrating it, and drying it with a band dryer or the like. At the time of coagulation, if necessary, latex and extender oil emulsified and dispersed may be mixed in advance and recovered as oil-extended rubber.
Commercially available E-SBR products 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 conventional solution polymerization methods, for example, using anionically polymerizable active metals in a solvent to polymerize styrene and butadiene, optionally in the presence of polar compounds.
Examples of anionically polymerizable active metals include alkali metals such as lithium, sodium and potassium; alkaline earth metals such as beryllium, magnesium, calcium, strontium and barium; lanthanoid rare earth metals such as lanthanum and neodymium. . Among them, alkali metals and alkaline earth metals are preferred, and alkali metals are more preferred. Furthermore, among alkali metals, organic alkali metal compounds are more preferably used.
Examples of solvents include aliphatic hydrocarbons such as n-butane, n-pentane, isopentane, n-hexane, n-heptane and isooctane; alicyclic hydrocarbons such as cyclopentane, cyclohexane and methylcyclopentane; toluene and the like. and aromatic hydrocarbons. These solvents are preferably used within a range in which the monomer concentration is 1 to 50% by mass.

Examples of organic alkali metal compounds include organic monolithium compounds such as n-butyllithium, sec-butyllithium, tert-butyllithium, hexyllithium, phenyllithium and stilbenelithium; - polyfunctional organic lithium compounds such as dilithio-2-ethylcyclohexane and 1,3,5-trilithiobenzene; sodium naphthalene, potassium naphthalene and the like. Among them, an organic lithium compound is preferred, and an organic monolithium compound is more preferred. The amount of the organic alkali metal compound to be used is appropriately determined according to the required molecular weight of S-SBR.
The organic alkali metal compound can also be used as an organic alkali metal amide by reacting it with a secondary amine such as dibutylamine, dihexylamine or dibenzylamine.
The polar compound is not particularly limited as long as it is normally used for adjusting the microstructure of the butadiene moiety and the distribution in the styrene copolymer chain without deactivating 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 -80 to 150°C, preferably 0 to 100°C, more preferably 30 to 90°C. The polymerization mode may be either a batchwise system or a continuous system. In order to improve the random copolymerizability of styrene and butadiene, styrene and butadiene are continuously or intermittently supplied to the reaction solution so that the composition ratio of styrene and butadiene in the polymerization system is within a specific range. is preferred.
The polymerization reaction can be stopped by adding an alcohol such as methanol or isopropanol as a polymerization terminator. Coupling of tin tetrachloride, tetrachlorosilane, tetramethoxysilane, tetraglycidyl-1,3-bisaminomethylcyclohexane, 2,4-tolylene diisocyanate, etc. that can react with the polymerization active terminal before adding the polymerization terminator. A polymerization terminal modifier such as 4,4'-bis(diethylamino)benzophenone, N-vinylpyrrolidone, etc. may be added. After termination of the polymerization reaction, the polymerization solution can be subjected to direct drying, steam stripping, or the like to separate the solvent and recover the target S-SBR. Before removing the solvent, the polymerization solution and the extender oil may be mixed in advance and recovered as an oil-extended rubber.

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

(Isoprene rubber (A-II))
Examples of 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 an organic alkali metal compound, such as neodymium organic acid-Lewis acid, or a lanthanide rare earth metal catalyst, or an organic alkali metal compound as in S-SBR can be used. Isoprene rubber polymerized with a Ziegler-based catalyst is preferred because of its high cis-isomer content. An isoprene rubber having an ultra-high cis-isomer content obtained using a lanthanoid-based rare earth metal catalyst may also be used.

The vinyl content of the isoprene rubber is preferably 50 mol % or less, more preferably 40 mol % or less, still more preferably 30 mol % or less. When the vinyl content is 50 mol % or less, good rolling resistance performance is obtained. The lower limit of the vinyl content is not particularly limited.
The vinyl content referred to here means 3,4-bonds and 1,2-bonds in monomer units consisting of 1,4-bonds, 1,2-bonds and 3,4-bonds in isoprene rubber. represents the percentage of the content of
Although the glass transition temperature varies depending on the vinyl content, it is preferably -20°C or lower, more preferably -30°C or lower.
The weight average molecular weight (Mw) of the isoprene rubber is preferably 90,000 to 2,000,000, more preferably 150,000 to 1,500,000. When Mw is within the above range, workability and mechanical strength are improved.
Part of the isoprene rubber is obtained by using a polyfunctional modifier such as tin tetrachloride, silicon tetrachloride, alkoxysilane having an epoxy group in the molecule, or alkoxysilane containing an amino group. It may have a branched structure or a polar functional group.

(Butadiene rubber (A-III))
Examples of butadiene rubber include Ziegler catalysts such as titanium tetrahalide-trialkylaluminum, diethylaluminum chloride-cobalt, trialkylaluminum-boron trifluoride-nickel, and diethylaluminum chloride-nickel; A commercially available butadiene rubber polymerized using an organic acid neodymium-lewis acid-based lanthanoid-based rare earth metal catalyst, or an organic alkali metal compound as in S-SBR can be used. Butadiene rubber polymerized with a Ziegler-based catalyst is preferred because of its high cis-isomer content. Also, a butadiene rubber having an ultra-high cis-isomer 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 even more preferably 30% by mass or less. When the vinyl content is 50% by mass or less, good rolling resistance performance is obtained. The lower limit of the vinyl content is not particularly limited. Although the glass transition temperature varies depending on the vinyl content, it is preferably -40°C or lower, more preferably -50°C or lower.
The term "vinyl content" as used herein refers to the ratio of the content of 1,2-bonds to the monomer units composed of 1,4-bonds and 1,2-bonds in the butadiene rubber.
The weight average molecular weight (Mw) of the butadiene rubber is preferably 90,000 to 2,000,000, more preferably 150,000 to 1,500,000. When Mw is within the above range, workability and mechanical strength are improved.
Part of the butadiene rubber is obtained by using a polyfunctional modifier such as tin tetrachloride, silicon tetrachloride, alkoxysilane having an epoxy group in the molecule, or alkoxysilane containing an amino group. It may have a branched structure or a polar functional group.

At least one of SBR, isoprene rubber, and butadiene rubber can be used together with one or more of butyl rubber, halogenated butyl rubber, ethylene propylene diene rubber, butadiene acrylonitrile copolymer rubber, chloroprene rubber, and the like. Moreover, the method for producing these is not particularly limited, and commercially available products can be used.

[Natural rubber]
Examples of the natural rubber used in the rubber component (A) include TSRs such as SMR, SIR, and STR, natural rubbers commonly used in the tire industry such as RSS, high-purity natural rubbers, epoxidized natural rubbers, and hydroxylated rubbers. Modified natural rubbers such as natural rubber, hydrogenated natural rubber, and grafted natural rubber can be mentioned. Among them, SMR20, STR20 and RSS#3 are preferable in terms of less variation in quality and availability. These may be used alone or in combination of two or more.
There are no particular restrictions on the method for producing the rubber used for the rubber component (A), and commercially available products may be used.

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

<Filler (B)>
The filler (B) has the effect of improving physical properties such as mechanical strength in the crosslinked product of the rubber composition. At least one of carbon black and silica is preferably used as the filler (B).
〔Carbon black〕
Examples of carbon black that can be used include furnace black, channel black, thermal black, acetylene black, and ketjen black. Among these, furnace black is preferable from the viewpoint of improving vulcanization speed and mechanical strength.
The average particle diameter of the carbon black is preferably 5 to 100 nm, more preferably 5 to 80 nm, even more preferably 5 to 70 nm, from the viewpoint of improving dispersibility, mechanical strength and hardness.
Examples of carbon black having an average particle size of 5 to 100 nm include commercially available furnace blacks such as Mitsubishi Chemical "Dia Black" and Tokai Carbon Co., Ltd. "Seist". Commercially available products of acetylene black include, for example, "Denka Black" manufactured by Denki Kagaku Kogyo. Commercially available products of Ketjenblack include, for example, "ECP600JD" manufactured by Lion Corporation.

From the viewpoint of improving the wettability and dispersibility of the rubber component (A) and the polymer (C) described later, the carbon black is subjected to acid treatment with nitric acid, sulfuric acid, hydrochloric acid, or a mixed acid thereof, or in the presence of air. A surface oxidation treatment may be performed by heat treatment at . Further, 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. Graphitization catalysts include boron, boron oxides (e.g., _{B2O2 , B2O3 , B4O3 , B4O5 ,} etc.), boron oxo acids (e.g., orthoboric acid, metaboric acid, tetraboric acid, etc.) and salts thereof, boron carbides (eg, B ₄ C, B ₆ C, etc.), boron nitride (BN), and other boron compounds are preferably used.

The particle size of carbon black can be adjusted by pulverization or the like. For pulverizing carbon black, high-speed rotary pulverizers (hammer mill, pin mill, cage mill), various ball mills (rolling mill, vibration mill, planetary mill), stirring mills (bead mill, attritor, circulation tube type mill, annular mill) are used. etc. can be used.
The average particle diameter of carbon black can be obtained by measuring the diameter of the particles with a transmission electron microscope and calculating the average value.

When the rubber composition of the present invention contains carbon black, its 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 10 to 80 parts by mass. When the content of carbon black is within the above range, the hardness of the resulting rubber molded article can be increased, and steering stability can be improved.

〔silica〕
Examples of silica include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate. 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 size of silica is preferably 0.5 to 200 nm, more preferably 5 to 150 nm, more preferably 10 to 10 nm, from the viewpoint of improving the processability, rolling resistance performance, mechanical strength, and wear resistance of the resulting rubber composition. 100 nm is more preferred.
The average particle size of silica can be obtained by measuring the diameter of particles with a transmission electron microscope and calculating the average value.

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

[Other fillers]
The rubber composition of the present invention may further contain a filler other than silica and carbon black as necessary for the purpose of improving mechanical strength, adjusting hardness, improving economy by blending an extender, etc. good.

Fillers other than silica and carbon black are appropriately selected depending on the application. Examples include organic fillers, clay, talc, mica, calcium carbonate, magnesium hydroxide, aluminum hydroxide, barium sulfate, titanium oxide, One or more inorganic fillers such as glass fibers and glass balloons can be used.

<Polymer (C) Containing Structural Unit Derived from 1,3,7-octatriene Containing 3,4-Linking Unit>
The rubber composition of the present invention comprises a polymer (C) containing structural units derived from 1,3,7-octatriene containing 3,4-linkage units (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, it is possible to obtain a rubber composition having high hardness and capable of providing a rubber molded article excellent in steering stability. be able to.
Although it does not limit the gist and technical scope of the present invention, it is due to the inclusion of a 3,4-bond unit in the structural unit derived from 1,3,7-octatriene of the polymer (C). It is considered that the improvement in the hardness of the rubber composition is due to the following effects.
That is, since the polymer (C) contains a 3,4-bond unit in the structural unit derived from 1,3,7-octatriene, the side chain has double bonds at two terminal ends, It is considered that the polymer (C) and the rubber component (A) are easily vulcanized, and the hardness of the obtained rubber molding can be increased.

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

Polymer (C) contains a structural unit derived from 1,3,7-octatriene, particularly if the structural unit derived from 1,3,7-octatriene contains a 3,4-linking unit Not limited. Among them, the content of the 3,4-bonding unit contained in the structural unit derived from 1,3,7-octatriene is preferably 2 mol % or more, more preferably 2 mol % or more, from the viewpoint of exhibiting the effects of the present invention. 2 to 40 mol %, more preferably 2 to 35 mol %.

The content of the 1,2-bonding unit contained in the structural unit derived from 1,3,7-octatriene is preferably 35 to 65 mol%, more preferably 40 to 60 mol%, still more preferably 40 to 50 mol %.
The content ratio of the 1,4-linkage unit contained in the structural unit derived from 1,3,7-octatriene is the content ratio of the 3,4-linkage unit and the content ratio of the 1,2-linkage unit. Consider the remainder. That is, the content ratio of the 1,4-bond is obtained from "100-(content ratio of 3,4-bond unit+content ratio of 1,2-bond unit)".
The content ratio of each bond unit is determined by ¹³ C-NMR measurement. Specifically, it can be determined according to the method described in Examples.

Also, the ratio of the content of the 3,4-linkage unit to the content of the 1,2-linkage unit (3,4-linkage unit/1,2-linkage unit) is preferably 0.04 to 0.04. 7, more preferably 0.045 to 0.6, still more preferably 0.05 to 0.5, even more preferably 0.1 to 0.45, 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 possessed by the structural unit derived from 1,3,7-octatriene increases the number of double bonds present in the rubber component (A), making it easier to vulcanize with the rubber component (A) and increasing the hardness of the resulting rubber molded product. , Tg and viscosity increases are suppressed, making handling easier.
The ratio (3,4-bond unit/1,2-bond unit) can be set within the above range by appropriately adjusting the polymerization temperature and the amount of the Lewis base.

The polymer (C) may be composed only of structural units derived from 1,3,7-octatriene, and structural units derived from 1,3,7-octatriene and 1,3,7- It may be composed of a structural unit derived from a monomer other than octatriene.
When the polymer (C) is a copolymer, examples of monomers 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 conjugated diene compounds 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-cyclohexadiene, myrcene ( 7-methyl-3-methyleneocta-1,6-diene) and the like. Among them, at least one selected from the group consisting of butadiene and isoprene is preferable.

Examples of aromatic vinyl compounds include styrene, α-methylstyrene, α-methyl-4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 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, 4 -(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-divinyl biphenyl, 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-aminoethylstyrene, vinylpyridine, 4-methoxystyrene, monochlorostyrene, dichlorostyrene, divinylbenzene, 2-chlorostyrene, 4-chlorostyrene, and the like. be done. Among them, styrene, α-methylstyrene and 4-methylstyrene are preferred.

Other vinyl compounds include α,β-unsaturated nitriles such as acrylonitrile, methacrylonitrile and 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, mesaconic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, -sec-butyl acrylate, -tert-acrylate 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, itaconic acid α,β-unsaturated carboxylic acid esters such as dimethyl, diethyl itaconate, and dibutyl itaconate; N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, N-butylacrylamide, N-octylacrylamide, N-phenylacrylamide , N-glycidylacrylamide, N,N'-ethylenebisacrylamide, N,N-dimethylacrylamide, N-ethyl-N-methylacrylamide, N,N-diethylacrylamide, N,N-dipropylacrylamide, 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-acryloyl imidazole, N,N'-diethyl-N,N'-ethylenebisacrylamide, N,N'-dimethyl-N,N'-hexamethylenebisacrylamide, di(N,N'-ethylene) acrylamide such as sacrylamide; These may use 1 type and may use 2 or more types together.

Structural units derived from 1,3,7-octatriene in the copolymer and structural units other than 1,3,7-octatriene relative to the sum of structural units derived from monomers other than 1,3,7-octatriene is preferably 10 to 80 mol%, more preferably 20 to 70 mol%, from the viewpoint of obtaining the effect resulting from the side chain of 1,3,7-octatriene, More preferably 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 The content of structural units derived from (mol%; sometimes referred to as 1,3,7-octatriene content α) is preferably 10 mol% or more, and is preferably 20 mol% or more. It is more preferably 30 mol % or more, and particularly preferably 40 mol % or more. The upper limit of the 1,3,7-octatriene content α is not particularly limited, but it may be 99 mol% or less, 90 mol% or less, or 80 mol% or less. may be 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 content ratio of each bonding mode are not particularly limited. For example, typical bonding modes of butadiene include 1,2-bond and 1,4-bond, and there are no particular restrictions on the bonding order and content ratio of each bonding mode.
Regarding the bond mode of butadiene, for example, the content of 1,2-bonds relative to the total bond mode is preferably 5 to 60 mol%, more preferably 10 to 50 mol%, and 15 to 45 mol%. is more preferable. The proportion of 1,4-bonds in all bonding modes is the remainder of the proportion of 1,2-bonds in all bonding modes.

Typical bonding modes of isoprene include 1,2-bonding, 3,4-bonding and 1,4-bonding, and there are no particular restrictions on the bonding order and content ratio of each bonding mode.
Regarding the bonding mode of isoprene, for example, the content of 1,4-bonds relative to the total bonding mode is preferably 40 to 95 mol%, more preferably 50 to 90 mol%, and 50 to 85 mol%. is more preferable, and 60 to 85 mol % is even more preferable. The content of 3,4-bonds relative to the total bonding mode is preferably 5 to 60 mol%, more preferably 5 to 50 mol%, even more preferably 5 to 40 mol%. Even more preferably ~40 mol%. The content ratio of 1,2-bonds with respect to all bonding modes is the balance of the content ratio of 1,4-bonds and 3,4-bonds.
The proportion of each binding mode is determined by ¹³ C-NMR measurements.

In the copolymer, the form of bonding 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 restricted. However, random, fully alternating, gradient, block, tapered, and combinations thereof are included, with random or block being preferred, and random being more preferred from the standpoint of manufacturability.

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

Further, 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 is lowered due to the high cohesive force between the carbon blacks. When the dispersibility is lowered, the rubber composition tends to generate heat, which leads to deterioration of the rolling resistance performance of the molded product, and may not satisfy the characteristics required for so-called fuel-efficient tires.
In the present invention, the weight average molecular weight (Mw) of the polymer (C) is preferably 50,000 to 180,000, more preferably 62,000 to 170,000, thereby further improving rolling resistance performance. can be done.

The molecular weight distribution (Mw/Mn) of the polymer (C) is preferably 4.0 or less, more preferably 3.0 or less, even more preferably 2.5 or less, still more preferably 2.0 or less. Although the lower limit of the molecular weight distribution (Mw/Mn) is not particularly limited, it 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, preferably 2 mol%, of all structural units. The following are more preferable.
Examples of the coupling agent include divinylbenzene; polyepoxy compounds such as epoxidized 1,2-polybutadiene, epoxidized soybean oil, and 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, diphenyl carbonate, and other ester compounds; alkoxysilane compounds such as ethylhexyloxy)silane, bis(triethoxysilyl)ethane, 3-aminopropyltriethoxysilane; and 2,4-tolylene diisocyanate.

When the polymer (C) is produced by anionic polymerization, which will be described later, the polymer (C) is a polymer that does not have a living anionic active species at the molecular terminal at the stage after the reaction with the terminal terminator after the polymerization reaction. Further, when the polymer (C) is produced by the anionic polymerization described later, at the stage before reacting the terminal terminator after the polymerization reaction, a polymer having a living anionic active species at the molecular terminal (referred to as a living anionic polymer There is something.) is.

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

The content of the polymer (C) is preferably 1 to 50 parts by mass, more preferably 5 to 40 parts by mass, still more preferably 8 to 30 parts by mass, based on 100 parts by mass of the rubber component (A). When the content of the polymer (C) is within the above range, it is possible to increase the hardness of the obtained rubber molding and improve the steering stability.

The presence or absence of a phase separation structure between the polymer (C) and the rubber component (A) does not matter, but when a phase separation structure is formed, the tan δ of the resulting vulcanized rubber increases, making it difficult to improve rolling resistance performance. may be. In addition, the compatibility at the phase separation interface between the polymer (C) and the rubber component (A) is reduced, and the resulting vulcanized rubber is likely to have reduced mechanical properties such as breaking strength, so that a phase separation structure is not formed. is preferred.

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

[Method for producing polymer (C)]
Polymer (C) can be produced by anionic polymerization using 1,3,7-octatriene as a raw material.
The anionic polymerization method is not particularly limited, and a known anionic polymerization method can be applied.
For example, 1,3,7-octatriene and optionally used monomers other than 1,3,7-octatriene (hereinafter, raw materials to be polymerized are sometimes referred to as raw material monomers). By supplying an anionic polymerization initiator to a mixture of and, polymerization reaction is performed to form a polymer having a living anionic active species in the reaction system. Then, the polymer (C) can be produced by adding a polymerization terminator.
A Lewis base and solvent may also be used if desired.

The polymerization reaction is preferably carried out inside a reactor pressurized with an inert gas, for example, in order to prevent water, oxygen, etc., which inhibit the polymerization reaction, from entering the reaction system. By using an inert gas atmosphere, it is possible to suppress the consumption of the anionic polymerization initiator and the growth terminal anion by the reaction with water or oxygen, and to control the polymerization reaction with high accuracy. Here, the term "growing terminal anion" refers to an anion that a polymer present in a reaction system during a polymerization reaction has at its molecular terminal, and the same applies hereinafter.

Raw material monomers, the anionic polymerization initiator described later, the Lewis base described later, the solvent described later, and the like used in the production of the polymer contain substances that inhibit the polymerization reaction by reacting with growing terminal anions, such as oxygen and water. , hydroxy compounds, carbonyl compounds, alkyne compounds, etc., and preferably stored in an atmosphere of an inert gas 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, or may be used as they are without being diluted 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 capable of initiating anionic polymerization.
As an anionic polymerization initiator, organic alkali metal compounds generally used in anionic polymerization of aromatic vinyl compounds and conjugated diene compounds can be used. Examples of the organic alkali metal compound include methyllithium, ethyllithium, propyllithium, isopropyllithium, butyllithium, sec-butyllithium, tert-butyllithium, isobutyllithium, pentyllithium, hexyllithium, butadienyllithium, cyclohexyllithium, phenyllithium, benzyllithium, p-toluyllithium, 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-ethylcyclohexane, 1,3, Organolithium compounds such as 5-trilithiobenzene, 1,3,5-trilithio-2,4,6-triethylbenzene; methyl sodium, ethyl sodium, n-propyl sodium, isopropyl sodium, n-butyl sodium, sec-butyl organic sodium compounds such as sodium, tert-butyl sodium, isobutyl sodium, phenyl sodium, sodium naphthalene, cyclopentadienyl sodium; Among them, n-butyllithium and sec-butyllithium are preferred. One of the organic alkali metal compounds may be used, or two or more thereof may be used in combination.

The amount of the anionic polymerization initiator used can be appropriately set according to the desired weight average molecular weight of the polymer or the solid content concentration of the reaction solution. It is preferably 10 to 3,000, more preferably 20 to 2,500, even more preferably 30 to 2,000, and particularly preferably 40 to 1,500.

(Lewis base)
In the method for producing the polymer (C), from the viewpoint of controlling the polymerization reaction, in particular, structural units derived from 1,3,7-octatriene and structural units derived from conjugated dienes other than 1,3,7-octatriene From the viewpoint of controlling the binding unit in , a Lewis base may be used, and is preferably used. 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 growing terminal anion.
When a Lewis base is used, the molar ratio (Lewis base/polymerization initiator) between the Lewis base and the polymerization initiator (anionic polymerization initiator) used for anionic polymerization is preferably 0.01 to 1,000. , more preferably 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-linkage units to the content of 1,2-linkage units in structural units derived from 1,3,7-octatriene (3,4-linkage units /1,2-bonding unit) is the preferred range described above. In addition, it is easy to achieve a high conversion rate of 1,3,7-octatriene in a short time.

The Lewis base includes (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). ], Among the Lewis bases (i), (i-1) a compound having one atom having a lone pair of electrons [hereinafter referred to as Lewis base (i-1). ] and (i-2) a compound having two or more atoms having a lone pair of electrons [hereinafter referred to as Lewis base (i-2). ] is mentioned.
The Lewis base may have monodentate coordination or multidentate coordination. Also, one Lewis base may be used, or two or more thereof 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 having preferably a total carbon number of 2 to 40 (more preferably a total carbon number of 2 to 20) such as tetrahydrofuran (THF) and tetrahydropyran; trimethylamine, triethylamine, tri Propylamine, triisopropylamine, tributylamine, triisobutylamine, trisec-butylamine, tritert-butylamine, tritert-hexylamine, tritert-octylamine, tritert-decylamine, tritert-dodecylamine, tritert- Tetradecylamine, tri-tert-hexadecylamine, tri-tert-octadecylamine, tri-tert-tetracosanylamine, tri-tert-octacosanylamine, 1-methyl-1-amino-cyclohexane, tripentylamine, triisopentyl amines, 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,N-disec-butylmonomethylamine, N,N-di-t ert-butylmonomethylamine, N,N-dipentylmonomethylamine, N,N-diisopentylmonomethylamine, N,N-dineopentylmonomethylamine, N,N-dihexylmonomethylamine, N,N-diheptylmonomethylamine , 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-butylmonoethylamine, N,N-ditert-butylmonoethylamine, N,N-dipentylmonoethylamine, N,N-diisopentylmonoethylamine, N,N-dineopentylmonoethylamine, N,N-dihexyl monoethylamine, N,N-diheptylmonoethylamine, N,N-dioctylmonoethylamine, N,N-dinonylmonoethylamine, N,N-didecylmonoethylamine, N,N-diundecylmonoethylamine, N,N -didodecylmonoethylamine, N,N-diphenylmonoethylamine, N,N-dibenzylmonoethylamine, N,N-dimethylaniline, N,N-diethylaniline, N-ethylpiperazine, N-methyl-N-ethylaniline , N-methylmorpholine, etc., preferably having a total carbon number of 3 to 60 (more preferably a total carbon number of 3 to 15).

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), from the viewpoint of controlling the polymerization reaction, in particular, structural units derived from 1,3,7-octatriene and structural units derived from conjugated dienes other than 1,3,7-octatriene Diethyl ether, diisopropyl ether, tetrahydrofuran, tetrahydropyran, triethylamine, and N,N-dimethylethylamine are preferred from the viewpoint of controlling the bonding unit in .
When the Lewis base (i-1) is used, the molar ratio between the atoms having a lone pair in the Lewis base (i-1) and the metal atom of the polymerization initiator used for the anionic polymerization (lone pair / metal atom of the polymerization initiator) is preferably 0.01 to 1,000, more preferably 0.1 to 500, even more preferably 2 to 300, 2 to 100 is particularly preferred, and 2-50 is most preferred. Within this range, in particular, the ratio of the content of 3,4-linkage units to the content of 1,2-linkage units in structural units derived from 1,3,7-octatriene (3,4-linkage units /1,2-bonding unit) is the preferred range described above. In addition, it is easy to achieve a high conversion rate 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, 1,2-di phenoxyethane, 1,2-dimethoxypropane, 1,2-diethoxypropane, 1,2-diphenoxypropane, 1,3-dimethoxypropane, 1,3-diethoxypropane, 1,3-diisopropoxypropane, Acyclic diethers preferably having a total carbon number of 4 to 80 (more preferably a total carbon number of 4 to 40) such as 1,3-dibutoxypropane and 1,3-diphenoxypropane; 1,4-dioxane, 2, Cyclic diethers preferably having a total carbon number of 4 to 80 (more preferably a total carbon number of 4 to 40) such as 2-di(tetrahydrofuryl)propane; diethylene glycol dimethyl 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, tetrabutylene glycol diethyl ether, etc., preferably having a total carbon number of 6 to 40 (more preferably a total carbon number of 6 to 20) N,N,N',N'-tetramethylethylenediamine (TMEDA), N,N,N',N'-tetraethylethylenediamine, N,N,N,N'',N''- Polyamines such as pentamethyldiethylenetriamine, tris[2-(dimethylamino)ethyl]amine, etc., preferably having a total carbon number of 6 to 122 (more preferably a total carbon number of 6 to 32, still more preferably a total carbon number of 6 to 15) is mentioned.

Among the Lewis bases (i-2), Lewis bases having monodentate coordination to the metal atom of the anionic polymerization initiator and Lewis bases having multidentate coordination to the metal atom of the anionic polymerization initiator There is a base.
As the Lewis base (i-2), from the viewpoint of controlling the polymerization reaction, in particular, structural units derived from 1,3,7-octatriene and structural units derived from conjugated dienes other than 1,3,7-octatriene 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-diisopropoxyethane, 2,2-di(tetrahydrofuryl)propane, N,N,N ',N'-tetramethylethylenediamine (TMEDA), 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 Lewis base having multidentate coordination with respect to the metal atom of the anionic polymerization initiator (e.g. 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. one (eg, —O—CH ₂ —O—, >N—CH ₂ —N<, etc.) or three or more (eg, —O—C ₃ H ₆ —O—, >N- C ₄ H ₈ —N<, —O—C ₃ H ₆ —N<, etc.), each atom tends to have monodentate coordination. On the other hand, when focusing on two atoms similarly having lone pairs, the number of shortest bridging carbons connecting them is two (for example, —O—C ₂ H ₄ —O—, >N—C ₂ H ₄ —N<, etc.), the two atoms with their lone pair of electrons tend to be multidentate (bidentate) to one metal atom of the anionic polymerization initiator.

When the Lewis base (i-2) is a Lewis base having monodentate coordination, the atom having a lone pair in the Lewis base (i-2) and the metal atom of the polymerization initiator used for the anionic polymerization The molar ratio (atom having lone pair/metal atom of polymerization initiator) is preferably 0.01 to 1,000, more preferably 0.1 to 500, and 2 to 300. is more preferred, 2 to 100 is particularly preferred, and 2 to 50 is most preferred. Within this range, in particular, the ratio of the content of 3,4-linkage units to the content of 1,2-linkage units in structural units derived from 1,3,7-octatriene (3,4-linkage units /1,2-bonding unit) is the preferred range described above. In addition, it is easy to achieve a high conversion rate of 1,3,7-octatriene in a short time.
On the other hand, when the Lewis base (i-2) is a Lewis base having multidentate coordination (bidentate coordination), an atom having a lone pair in the Lewis base (i-2) and the anionic polymerization The molar ratio of the metal atom of the polymerization initiator used in (atom having an unshared electron pair/metal atom of the polymerization initiator) is preferably 0.01 to 50, more preferably 0.1 to 10. It is preferably from 0.1 to 5, and particularly preferably from 0.3 to 4. Within this range, in particular, the ratio of the content of 3,4-linkage units to the content of 1,2-linkage units in structural units derived from 1,3,7-octatriene (3,4-linkage units /1,2-bonding unit) is the preferred range described above. In addition, it is easy to achieve a high conversion rate of 1,3,7-octatriene in a short time.
In the case of a Lewis base that has both monodentate and multidentate (bidentate) coordination, an atom having a monodentate lone pair of electrons and a polydentate (bidentate It is preferable to pay attention to each combination of two or more atoms having a lone pair of electrons having a (characteristic) and refer to the above description to determine the amount of Lewis base to be used.

(solvent)
Although the method for producing the polymer (C) can be carried out in the absence of a solvent, it is preferably carried out in the presence of a solvent for the purpose of efficiently removing the heat of polymerization.
The type of solvent is not particularly limited as long as it does not substantially react with the anionic polymerization initiator and the growing terminal anion. A hydrocarbon-based solvent is preferable from the viewpoint of accurately controlling the bonding unit in the structural unit derived from a conjugated diene other than 3,7-octatriene by the Lewis base.
Hydrocarbon solvents include, for example, isopentane (27.9°C; boiling point at 1 atm; hereinafter the same), pentane (36.1°C), cyclopentane (49.3°C), hexane (68°C), .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), 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.), m-xylene (139.1 ° C.), o- Aromatic hydrocarbons such as xylene (144.4° C.), propylbenzene (159.2° C.) and butylbenzene (183.4° C.) can be mentioned.
It is preferable to use a solvent having a boiling point lower than that of 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 point of view, solvents include 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 point of view, cyclohexane and n-hexane are more preferred.
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 It is preferably adjusted to 15 to 55% by mass. Further, the concentration of the living anionic polymer in the reaction system is preferably adjusted to 5% by mass or more, more preferably 10 to 80% by mass. By using the solvent in such an amount, the heat of polymerization can be removed at a level suitable for industrial production, so that the polymerization time can be easily shortened and a high conversion of 1,3,7-octatriene can be achieved. easy to achieve. Furthermore, if the solvent is used in such an amount, it is easy to narrow the molecular weight distribution.
From the viewpoint of simplifying the solvent removal step, it is also possible to adjust the solid content concentration of the reaction solution after the completion of the anionic polymerization to be 35 to 80% by mass, and 50 to 70% by mass. It is also possible to adjust the

(Reactor)
The type of reactor is not particularly limited, and a complete mixing reactor, a tubular reactor, and a reaction apparatus in which two or more of these are connected in series or in parallel can be used. From the viewpoint of producing a polymer with a high solution viscosity and a narrow molecular weight distribution (Mw/Mn), it is preferable to use a complete mixing reactor. There are no particular restrictions on the stirring blades of the reactor, but examples include Maxblend blades, full zone blades, paddle blades, propeller blades, turbine blades, fan turbine blades, Faudler blades, Blue Margin blades, etc. Any two of these blades may be used. A combination of the above may also be used. When the viscosity of the resulting polymer solution is high, it is preferable to use Maxblend impellers and full zone impellers from the viewpoint of narrowing the molecular weight distribution (Mw/Mn) and promoting jacket heat removal.
The stirring method may be upper stirring or lower stirring.

There are no particular restrictions on the polymerization method, and any of a batch system, a semi-batch system, and a continuous system may be used. The complete mixing reactor may have an external jacket for the purpose of heating and cooling the solution inside the reactor. Also, cooling baffles or cooling coils or the like may be provided inside the reactor for the purpose of increasing cooling heat transfer as desired. Furthermore, a reflux condenser may be attached directly or indirectly to the gas phase portion. From the viewpoint of controlling the amount of heat of polymerization to be removed, the reactor may be pressurized using an inert gas, or may be decompressed to the atmospheric pressure or less. When the internal pressure of the reactor is reduced to atmospheric pressure or lower, a pump for exhausting the inert gas may be installed via a reflux condenser. Although the structure of the reflux condenser is not particularly limited, it is preferable to use a multitubular reflux condenser. A plurality of reflux condensers may be connected in series or in parallel, and a different refrigerant may be passed through each reflux condenser. The temperature of the refrigerant passing through the reflux condenser is not particularly limited as long as it is in the range from the temperature at which the refluxing solvent does not freeze to the temperature of the reaction solution, preferably -20 to 50°C, more preferably 5 to 30°C. It is economical because it does not require a large refrigerator.

(polymerization temperature)
Although the polymerization temperature is not particularly limited, it is preferably carried out at a temperature above the freezing point of the raw materials and solvent used and below a temperature at which the raw materials and solvent used are not thermally decomposed. It is preferably -50 to 200°C, more preferably -20 to 120°C, still more preferably 15 to 100°C. When the polymerization temperature is within the above range, the ratio of the content of 3,4-linkage units to the content of 1,2-linkage units in structural units derived from 1,3,7-octatriene (3, 4-linkage unit/1,2-linkage unit) is the preferred range above. In addition, while maintaining a shortened polymerization time and a high conversion rate of 1,3,7-octatriene, the mechanical properties are obtained by suppressing the formation of low-molecular-weight polymers caused by partial thermal degradation of growing terminal anions. Excellent polymers can be produced.

(polymerization pressure)
Polymerization can be carried out favorably as long as contamination with substances that inhibit the polymerization reaction by reacting with growing terminal anions, such as air containing oxygen and water, is suppressed.
When using a solvent having a boiling point below the polymerization temperature, the temperature may be controlled by controlling the pressure with an inert gas to control the amount of solvent vapor generated. is used, the temperature may be controlled by reducing the pressure in the reaction system using an exhaust pump and controlling the amount of vapor generated from the solvent.
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 the amount of inert gas used can be reduced, but also the reactor with high pressure resistance and the inert gas can be removed from the system. Polymerization can be economically advantageous because a pump for exhausting the gas is not required.

(polymerization time)
The polymerization time is not particularly limited, but it is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours, in order to suppress the formation of low-molecular-weight polymers due to partial thermal degradation of growing terminal anions. It is easy to produce a polymer having excellent mechanical properties.

(Polymerization terminator and coupling agent)
In the method for producing the polymer (C), it is preferable to terminate the polymerization reaction by adding a polymerization terminator or a coupling agent to the reaction system. Polymerization terminator or coupling agent includes, for example, hydrogen molecule; 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, triethylsilyl iodide, tributylsilyl fluoride Halogen compounds such as , tributylsilyl chloride, tributylsilyl bromide, tributylsilyl iodide, triphenylsilyl fluoride, triphenylsilyl chloride, triphenylsilyl bromide, triphenylsilyl iodide; 2-heptanone, 4-methyl- Ketones such as 2-pentanone, cyclopentanone, 2-hexanone, 2-pentanone, cyclohexanone, 3-pentanone, acetophenone, 2-butanone, and acetone; Esters such as methyl acetate, ethyl acetate, and butyl acetate; Ethylene oxide, propylene oxide, Epoxy compounds such as 1,2-butylene oxide, 2,3-butylene oxide, styrene oxide, cyclohexene oxide; Chlorosilane, octyldichlorosilane, nonyldichlorosilane, decyldichlorosilane, phenyldichlorosilane, dimethylchlorosilane, diethylchlorosilane, dipropylchlorosilane, dibutylchlorosilane, dipentylchlorosilane, dihexylchlorosilane, diheptylchlorosilane, dioctylchlorosilane, dinonylchlorosilane, didecyl Chlorosilane, methylpropylchlorosilane, methylhexylchlorosilane, methylphenylchlorosilane, diphenylchlorosilane, dimethylmethoxysilane, dimethylethoxysilane, dimethylpropoxysilane, dimethylbutoxysilane, dimethylphenoxysilane, dimethylbenzyl Oxysilane, diethylmethoxysilane, diethylethoxysilane, diethylpropoxysilane, diethylbutoxysilane, diethylphenoxysilane, diethylbenzyloxysilane, dipropylmethoxysilane, dipropylethoxysilane, dipropylpropoxysilane, dipropylbutoxysilane, dipropylphenoxysilane Silane, dipropylbenzyloxysilane, dibutylmethoxysilane, dibutylethoxysilane, dibutylpropoxysilane, dibutylbutoxysilane, dibutylphenoxysilane, dibutylbenzyloxysilane, diphenylmethoxysilane, diphenylethoxysilane, diphenylpropoxysilane, diphenylbutoxysilane, diphenyl Phenoxysilane, diphenylbenzyloxysilane, dimethylsilane, diethylsilane, dipropylsilane, dibutylsilane, diphenylsilane, diphenylmethylsilane, diphenylethylsilane, diphenylpropylsilane, diphenylbutylsilane, trimethylsilane, triethylsilane, tripropylsilane, tributylsilane, triphenylsilane, methylsilane, ethylsilane, propylsilane, butylsilane, phenylsilane, methyldiacetoxysilane, polymethylhydrosiloxane, polyethylhydrosiloxane, polypropylhydrosiloxane, polybutylhydrosiloxane, polypentylhydrosiloxane, poly Hexylhydrosiloxane, polyheptylhydrosiloxane, polyoctylhydrosiloxane, polynonylhydrosiloxane, polydecylhydrosiloxane, polyphenylhydrosiloxane, 1,1,3,3-tetramethyldisiloxane, methylhydrocyclosiloxane, ethylhydrocyclosiloxane siloxane, propylhydrocyclosiloxane, butylhydrocyclosiloxane, phenylhydrocyclosiloxane, 1,1,3,3-tetramethyldisilazane, 1,1,3,3-tetraethyldisilazane, 1,1,3,3- Examples include silyl hydride compounds such as tetrapropyldisilazane, 1,1,3,3-tetrabutyldisilazane and 1,1,3,3-tetraphenyldisilazane.
The polymerization terminator or coupling agent may be used alone or in combination of two or more.
The polymerization terminator or coupling agent may be used after being diluted with a solvent that can be used in the polymerization reaction. The amount of the polymerization terminator or coupling agent to be used is not particularly limited, but it is preferable from the viewpoint of solvent recovery and reuse that the amount of the polymerization terminator or coupling agent is not excessive with respect to the growing terminal anion, and It is also preferable in that the amount of the hydrogenation catalyst used can be reduced when the polymer is hydrogenated.

The conversion rate of 1,3,7-octatriene obtained by gas chromatography after anionic polymerization is preferably 30.0% or more, more preferably 40.0% or more, and more preferably 50.0%. It is more preferable that it is above.

(Hydrogenation reaction)
From the viewpoint of heat resistance, oxidation resistance, weather resistance, ozone resistance, etc. of the polymer, the carbon-carbon double bond of the polymer may be hydrogenated. Usually, a hydrogenation catalyst is added to a polymer solution obtained by terminating polymerization in the above-described method for producing a polymer or a polymer solution diluted with the solvent as necessary, and reacted with hydrogen to produce a polymer. Can produce hydrides.
Hydrogenation catalysts include, for example, Raney nickel; heterogeneous catalysts in which metals such as Pt, Pd, Ru, Rh, and Ni are supported on simple substances such as activated carbon, alumina, and diatomaceous earth; transition metal compounds, alkylaluminum compounds, and alkyllithium Ziegler-type catalysts in combination with other compounds; metallocene-based catalysts;

The temperature of the hydrogenation reaction is preferably −20 to 250° C., which is higher than the freezing point of the solvent and lower than the thermal decomposition temperature of the polymer. °C is more preferred. 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 hydrogenation catalyst even if thermal decomposition of the hydrogenation catalyst occurs concurrently. From the viewpoint of reducing the amount of hydrogenation catalyst used, 60 to 100° C. is more preferable.

Hydrogen can be used in a gaseous state, and its pressure is not particularly limited as long as it is normal pressure or higher. If the pressure is 20 MPaG or less, the hydrogenation reaction can be carried out with a small amount of the hydrogenation catalyst used even if the hydrogenation catalyst is simultaneously hydrocracked. From the viewpoint of reducing the amount of hydrogenation catalyst used, 0.5 to 10 MPaG is more preferable.
The time required for the hydrogenation reaction can be appropriately selected depending on the conditions, but from the viewpoint of industrially advantageous production of hydrogenated polymer, it is preferably in the range of 10 minutes to 24 hours from the start of coexistence with the catalyst.
After completing the hydrogenation reaction, the reaction mixture can be diluted or concentrated with the 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 subjected to a concentration operation and then supplied to an extruder 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 it, or the polymer may be isolated by contacting it with a heated inert gas to remove the solvent and the like.

<Vulcanization accelerator aid>
The rubber composition of the present invention may contain an auxiliary vulcanization accelerator. Examples of vulcanization acceleration aids include fatty acids such as stearic acid, metal oxides such as zinc oxide, and fatty acid metal salts such as zinc stearate. These may be used alone or in combination of two or more. When the vulcanization accelerator is contained, its content is preferably 0.1 to 15 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of the rubber component (A).

<Vulcanizing agent>
A vulcanizing agent is preferably added to the rubber composition of the present invention. Vulcanizing agents include, for example, sulfur and sulfur compounds. These may be used alone or in combination of two or more. The content of the vulcanizing agent is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 10 parts by mass, and 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>
A vulcanization accelerator may be added to the rubber composition of the present invention. Examples of vulcanization accelerators include guanidine-based compounds, sulfenamide-based compounds, thiazole-based compounds, thiuram-based compounds, thiourea-based compounds, dithiocarbamic acid-based compounds, aldehyde-amine-based compounds or aldehyde-ammonia-based compounds, and imidazoline-based compounds. compound, xanthate-based compound, and the like. These may be used alone or in combination of two or more. When the vulcanization accelerator is contained, its content is preferably 0.1 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, per 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. Silane coupling agents include sulfide-based compounds, mercapto-based compounds, vinyl-based compounds, amino-based compounds, glycidoxy-based compounds, nitro-based compounds, chloro-based compounds, and the like.
Examples of sulfide compounds include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxy silylethyl) tetrasulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(3-trimethoxysilylpropyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(3-trimethoxysilylpropyl) Disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide and the like.
Mercapto-based compounds include, for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane and the like.
Vinyl compounds include, for example, vinyltriethoxysilane and vinyltrimethoxysilane.
Examples of amino compounds include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane. Silane etc. are mentioned.
Examples of glycidoxy-based compounds include γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, and the like. mentioned.
Nitro compounds include, for example, 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane.
Examples of chloro-based compounds include 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, and 2-chloroethyltriethoxysilane.
These silane coupling agents may be used alone or in combination of two or more. Among them, silane coupling agents containing sulfur such as sulfide-based compounds and mercapto-based compounds are preferable from the viewpoint of a large reinforcing effect. Sulfide, 3-mercaptopropyltrimethoxysilane is 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, still more preferably 1 to 15 parts by mass. When the content of the silane coupling agent is within the above range, dispersibility, reinforcing properties, and abrasion resistance are improved.

<Other ingredients>
The rubber composition of the present invention is intended to improve processability, fluidity, etc., within a range that does not impair the effects of the present invention, and if necessary, silicone oil, aromatic 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, coumarone/indene resins, phenol Resin components such as system resins, liquid polymers such as low-molecular-weight polybutadiene, low-molecular-weight polyisoprene, low-molecular-weight styrene-butadiene copolymers, low-molecular-weight styrene-isoprene copolymers, and unmodified polymers as softeners. good. The copolymer may be in any form of polymerization such as block or random. The weight average molecular weight (Mw) of the liquid polymer is preferably 500 to 100,000 from the viewpoint of workability. When the rubber composition of the present invention contains the process oil, resin component, liquid polymer, or unmodified polymer as a softening agent, the content is from 50 parts by mass to 100 parts by mass of the rubber component (A). Less is preferred.

The rubber composition of the present invention may optionally contain an antioxidant, an antioxidant, a wax, a lubricant, and the like for the purpose of improving weather resistance, heat resistance, oxidation resistance, etc., to the extent that the effects of the present invention are not impaired. 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, antibacterial agents One or two or more additives such as fungicides and fragrances may be contained.
Anti-aging agents include, for example, amine-ketone compounds, imidazole compounds, amine compounds, phenol compounds, sulfur compounds and phosphorus compounds.
Examples of antioxidants include hindered phenol compounds, phosphorus compounds, lactone compounds, hydroxyl compounds 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. Cross-linking agents include, for example, oxygen, organic peroxides, phenol resins and amino resins, quinones and quinonedioxime derivatives, halogen compounds, aldehyde compounds, alcohol compounds, epoxy compounds, metal halides and organic metal halides, and silane compounds. etc. These may be used alone or in combination of two or more. The content of the cross-linking agent is preferably 0.1 to 10 parts by mass per 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 above components may be uniformly mixed. Examples of uniform mixing methods include tangential or intermeshing internal kneaders such as Kneaderruder, Brabender, Banbury mixer, and internal mixer, single-screw extruders, twin-screw extruders, mixing rolls, rollers, and the like. and can be carried out in a temperature range of 70 to 270°C.

The rubber composition of the present invention can also be used as a vulcanized rubber by vulcanization. Although there are no particular restrictions on the vulcanization conditions and method, it is preferable to use a vulcanization mold and pressurize and heat at 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 the rubber composition of the present invention at least in part. Therefore, it has high hardness and excellent steering stability.

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

In each of the following examples, 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 The bonding unit and ratio (3,4-bonding unit/1,2-bonding unit) of were obtained according to the following measurement method.

(1) Method for Measuring Conversion Rate To 5.00 g of the polymerization termination solution obtained after the completion of the polymerization reaction, 1.00 g of ethylene glycol dimethyl ether was added, and this mixture was analyzed by gas chromatography under the following measurement conditions.
It should be noted that "the area ratio (S1) of 1,3,7-octatriene and ethylene glycol dimethyl ether at the start of the polymerization reaction at 0 hours" and "unreacted 1,3,7-octatriene and ethylene glycol dimethyl ether after the polymerization reaction The conversion rate (%) of 1,3,7-octatriene was calculated based on the following formula 1 from the area ratio (S2) of ".
Further, from the "area ratio of isoprene to ethylene glycol dimethyl ether before reaction (S3) at time 0 after the start of the polymerization reaction" and "area ratio of unreacted isoprene to ethylene glycol dimethyl ether after reaction (S4)", the following formula 2 is obtained. Based on this, the conversion rate (%) of isoprene was calculated.
<Gas chromatography measurement conditions>
Apparatus: "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
Vaporization 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./min and held for 5 minutes.

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

(2) Measurement method of weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn) To 0.10 g of the obtained polymer was added 60.0 g of tetrahydrofuran to prepare a uniform solution, and this solution was subjected to the following measurement conditions. was analyzed by gel permeation chromatography, the weight average molecular weight (Mw) and number average molecular weight (Mn) were determined in terms of standard polystyrene, and the molecular weight distribution (Mw/Mn) was calculated.
<Gel permeation chromatography measurement conditions>
Apparatus: "HLC-8320GPC EcoSEC" manufactured by Tosoh Corporation
Column: Two "TSKgel Super Multipore HZ-M" manufactured by Tosoh Corporation (inner diameter 4.6 mm, length 150 mm) were used by connecting them 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) Coupling Unit To 150 mg of the obtained polymer was added 1.00 g of deuterated chloroform to prepare a uniform solution, and this solution was subjected to ¹³ C-NMR measurement under the following measurement conditions.
< ¹³ C-NMR measurement conditions>
Device: "JNM-LA500" manufactured by JEOL Ltd.
Reference substance: Tetramethylsilane Measurement temperature: 25°C
Accumulated times: 15,000 times

As a result of the ¹³ C-NMR measurement, the "peak attributable to the 7-position carbon atom of the 1,2-bond unit" of 1,3,7-octatriene was δ 138.1 to 138.6 ppm, and "1,4- The peak attributed to the 7-position carbon atom of the bonding unit and the 7-position carbon atom of the 3,4-bond unit” to δ 138.8 to 139.4 ppm, and the “peak attributed to the 2-position carbon atom of the 3,4-bond unit ” was observed at δ 140.9 to 141.6 ppm. The peak area corresponding to the 7-position carbon atom of the 1,4-bond unit (1,4-bond attributed peak area).
The proportions of 1,2-, 1,4-, and 3,4-bond units derived from 1,3,7-octatriene contained in the polymer were obtained from the following formulas 4 to 6, respectively.

Further, regarding the polymer (C-9) obtained in Production Example 9 described later, the "peak attributable to the 3-position carbon atom of the 1,2-bond unit" of isoprene was set to δ 140.5 to 141.0 ppm, and " The peak attributed to the 3-position carbon atom of the 1,4-bond unit” is δ122.0-126.9 ppm, and the “peak attribute to the 1-position carbon atom of the 3,4-bond unit” is δ110.2-112. Observed at 2 ppm.
The proportions of isoprene-derived 1,2-linkage units, 1,4-linkage units and 3,4-linkage units contained in the copolymer were obtained from the following formulas 4 to 6, respectively.

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

(Production Example 1: Production of polymer (C-1) (1,3,7-octatriene homopolymer))
After purging the inside of a 1 L capacity SUS316 (registered trademark) autoclave equipped with a thermometer, an electric heater, an electromagnetic induction stirrer, a chemical feed 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. Then, after the internal pressure was adjusted to 0.3 MPaG with argon, 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 of a cyclohexane solution containing 1.26 mmol/g of sec-butyllithium (10.42 mmol as sec-butyllithium). After that, the internal pressure was adjusted to 0.3 MPaG with argon. This point was defined as the 0th hour of the polymerization reaction, and the reaction was continued for 1 hour while controlling the liquid temperature to 50°C.
Thereafter, 4.586 g of a cyclohexane solution containing 2.5 mmol/g of ethanol (11.465 mmol as ethanol) was added to terminate the polymerization reaction.
Next, the entire amount of the obtained polymerization termination solution was transferred to a 1 L eggplant flask, and most of the solvent was distilled off while heating to 40° C. under 100 kPaA using a rotary evaporator. Further, the eggplant flask was transferred to a vacuum dryer and dried for 12 hours while heating at 25° C. under 0.1 kPaA to obtain 57.85 g of liquid polymer (C-1). The resulting 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) (1,3,7-octatriene homopolymer))
A polymerization reaction was carried out in the same manner as in Production Example 1, except that each reagent, the amount used, and the reaction conditions were changed as shown in Table 1 to obtain polymers (C-2) to (C-8). rice field. The obtained polymers (C-2) to (C-8) were evaluated using the measurement method described above. Table 1 shows the results. In addition, in Table 1, a blank represents no compounding.

(Production Example 9: Production of polymer (C-9) (1,3,7-octatriene-isoprene copolymer))
After purging the inside of a 1 L capacity SUS316 (registered trademark) autoclave equipped with a thermometer, an electric heater, an electromagnetic induction stirrer, a chemical feed port, and a sampling port, with argon, 232.0 g of cyclohexane was charged as a solvent. Subsequently, after the internal pressure was adjusted to 0.3 MPaG with argon, the temperature was raised to 50° C. over 30 minutes while stirring at 250 rpm. Under an argon stream, 1.43 g (19.78 mmol) of tetrahydrofuran (THF) was charged, followed by 3.14 g of a cyclohexane solution containing 1.26 mmol/g of sec-butyllithium (3.96 mmol as 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 were mixed and fed into the autoclave containing sec-butyllithium over 0.5 hours. bottom. The time point at which the charging was started was defined as 0 hour from the start of the polymerization reaction, and the reaction was carried out for 2 hours while controlling the liquid temperature to be 50°C.
Thereafter, 1.740 g of a cyclohexane solution containing 2.5 mmol/g of ethanol (4.350 mmol as ethanol) was added to terminate the polymerization reaction.
Next, the entire amount of the obtained polymerization termination solution was transferred to a 1 L eggplant flask, and most of the solvent was distilled off while heating to 40° C. under 100 kPaA using a rotary evaporator. Further, the eggplant flask was transferred to a vacuum dryer and dried for 12 hours while heating to 25° C. under 0.1 kPaA to obtain 146.96 g of a liquid copolymer (polymer (C-9)). The resulting 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) (1,3,7-octatriene homopolymers))
Polymerization reactions were carried out in the same manner as in Production Example 1, except that each reagent, the amount 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 to 3, 5 to 7, and 9 produced using tetrahydrofuran (THF) as the Lewis base (i-1), the content of 3,4-linkage units relative to the content of 1,2-linkage units 1,3,7-octatriene homopolymers and 1,3,7-octatriene-isoprene copolymers having a ratio of 0.055 to 0.128 were obtained.
In Preparation Examples 4 and 8, which were prepared using N,N,N',N'-tetramethylethylenediamine (TMEDA) as the Lewis base (i-2), 3,4 - A 1,3,7-octatriene homopolymer having a content ratio of linking units of 0.313 to 0.365 was obtained.
1,3,7-octatriene homopolymers containing no 3,4-linkage units were obtained in Comparative Preparation Examples 1 and 2 in which no Lewis base was used.

Components used in Examples and Comparative Examples are as follows.
[Rubber component (A)]
・Natural rubber: “STR20” Thai natural rubber [filler (B)]
・ Carbon black: “Diablack H” manufactured by Mitsubishi Chemical Corporation, average particle size 30 nm
[Polymer (C)]
Polymers (C-1) to (C-8): 1,3,7-octatriene homopolymers 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 homopolymers obtained in Comparative Production Examples 1 and 2 [other components]
· Anti-aging agent: "Nocrac 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 Chemical Industry Co., Ltd. vulcanization accelerator aid (1): zinc white, "zinc oxide" Sakai Chemical Industry Co., Ltd. vulcanization accelerator aid (2): stearic acid, "Lunac S-20" Kao Corporation Made

(Example 1)
The rubber component (A), the filler (B), the polymer (C), the anti-aging agent and the vulcanization accelerator aid were added according to the blending ratio (parts by mass) shown in Table 2, respectively. After being put 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, this mixture was placed in 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 a rubber composition weighing about 240 g. The obtained rubber composition was press-molded (145° C., 14 minutes) to prepare a vulcanized rubber sheet (thickness: 2 mm). solubility)] was evaluated. Table 2 shows the results. In addition, in Table 2, a blank represents 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 (thickness: 2 mm). solubility)] was evaluated. Table 2 shows the results.
The measurement method for each evaluation is as follows.

(5) Hardness (steering stability)
Using the rubber composition sheets produced in Examples and Comparative Examples, the hardness was measured with a type A hardness tester in accordance with JIS K6253 (2012), and used as an index of flexibility. If the numerical value is less than 50, the tire will deform greatly when the composition is used in the tire, resulting in poor steering stability.

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

The rubber compositions of Examples 1 to 9 containing the polymer (C) containing structural units derived from 1,3,7-octatriene containing 3,4-linking units contained the polymer (C). It can be seen that the hardness of the molded article is higher than that of the rubber compositions of Comparative Examples 1 and 2, which did not contain the rubber composition. Moreover, 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 compatible state at the molecular level.

(7) Value of tan δ (rolling resistance performance)
A test piece of 40 mm length × 7 mm width was cut out from the rubber composition sheets prepared in Examples 5 to 8 and Comparative Example 1, and measured using a dynamic viscoelasticity measuring device manufactured by GABO at a measurement temperature of 60 ° C., a frequency of 10 Hz, The value of tan δ was measured under conditions of static strain of 10% and dynamic strain of 2%.
Since tan δ at 60° C. and rolling performance of the tire show a high correlation, this value was used as an index of 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. Incidentally, the smaller the numerical 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 polymer (C) has an Mw of 50,000 or more, are further improved in rolling resistance performance.

Claims (5)

A rubber component (A) consisting of at least one of synthetic rubber and natural rubber (excluding 1,3,7-octatriene), a filler (B), and a structure derived from 1,3,7-octatriene a polymer (C) containing a unit (provided that the polymer (C) does not contain a structural unit derived from farnesene),
The filler (B) is at least one of carbon black and silica,
A rubber composition in which the structural unit derived from 1,3,7-octatriene includes a 3,4-linkage unit. The structural unit derived from 1,3,7-octatriene includes a 3,4-bonding unit and a 1,2-bonding unit, and the 3,4- 2. The rubber composition according to claim 1, wherein the content ratio of the bonding units (3,4-bonding units/1,2-bonding units) is 0.04 to 0.7. 3. The rubber composition according to claim 1, 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 3, wherein the polymer (C) has a weight average molecular weight (Mw) of 1,000 to 1,000,000. A tire at least partly made of the rubber composition according to any one of claims 1 to 4.