JP6144464B2 - Rubber composition for tire and pneumatic tire - Google Patents

Description

The present invention relates to a rubber composition for a tire and a pneumatic tire using the same.

In recent years, the characteristics required of pneumatic tires for automobiles are diverse, such as low fuel consumption (rolling resistance characteristics), grip performance (steering stability), and wear resistance. Have been devised.

As a method for improving the wear resistance, for example, a method using natural rubber or butadiene rubber as a rubber component is known. However, when this method is used, grip performance tends to deteriorate. Moreover, as a method of achieving both wear resistance and grip performance, for example, a method of increasing the amount of reinforcing agent such as carbon black or silica can be mentioned, but the rolling resistance characteristic tends to deteriorate.

Furthermore, as another method for improving wear resistance and grip performance, a method of blending a polymer obtained by polymerizing only an aromatic vinyl monomer, a hydrogenated low molecular weight aromatic vinyl-conjugated diene copolymer is blended. A method is disclosed (Patent Documents 1 and 2). However, in addition to gripping performance and wear resistance, improving rolling resistance characteristics in a well-balanced manner is usually accompanied by difficulties in these performances, and further improvements are desired.

JP 2007-112994 A JP 2005-225946 A

The present invention solves the above-mentioned problems, and provides a rubber composition for a tire that can improve the grip performance (particularly wet grip performance), wear resistance, and rolling resistance characteristics in a well-balanced manner, and a pneumatic tire using the same. Objective.

In general, when a polymer is synthesized, purification is performed after completion of the polymerization reaction to increase the purity of the obtained polymer. In particular, in the case of a rubber composition for tires, if the polymer used has a low purity, rolling resistance characteristics and wear resistance are expected to deteriorate, and a polymer having a high purity has been used. On the other hand, the inventors of the present invention blended a rubber composition that was not sufficiently purified into a rubber composition as a test, and contrary to expectation, grip performance (particularly wet grip performance), wear resistance, and rolling resistance. We found that the characteristics can be improved in a well-balanced manner. Furthermore, as a result of earnest examination about this cause, the tetramethylethylenediamine used in the polymerization is contained together with the polymer (existing with the polymer as an impurity), so that the improvement in the performance can be seen, The present inventors have found that the above-described improvement in performance can also be seen when organic compounds having nitrogen atoms (particularly amines) other than tetramethylethylenediamine are contained together with the polymer. Furthermore, surprisingly, when the rubber component, the polymer, and the organic compound are normally kneaded (the components are individually put into a kneader and kneaded) to prepare a rubber composition, The effect of improving the performance is small, and the rubber component and the polymer composition are kneaded after mixing the polymer and the organic compound in advance (that is, as the polymer composition in advance). It was found that the effect of improving the performance was great when the rubber composition was prepared by putting it into a kneader and kneading it to complete the present invention.
That is, the present invention is obtained by mixing a rubber component, a polymer composition, and silica, and the polymer composition contains a polymer of a conjugated diene compound and / or an aromatic vinyl compound, and a nitrogen atom. And the weight average molecular weight of the polymer is 1.0 × 10 ^{3 to} 1.0 × 10 ⁴ , and the content of the organic compound in 100% by mass of the polymer composition is 0.1 to 10%. It is related with the rubber composition for tires which is 20 mass%.

The organic compound is preferably an amine.

The polymer composition is preferably obtained by adding the organic compound before the polymerization reaction, during the polymerization reaction, and / or after the completion of the polymerization reaction.

The polymer is preferably a copolymer of a conjugated diene compound and an aromatic vinyl compound.

The polymer is preferably a styrene butadiene copolymer.
Moreover, it is preferable that the styrene content of the said styrene butadiene copolymer is 0.1-55 mass%.

In the tire rubber composition, the content of the polymer composition is 3 to 40 parts by mass and the silica content is 5 to 150 parts by mass with respect to 100 parts by mass of the rubber component. .

The present invention also relates to a pneumatic tire produced using the rubber composition.

According to the present invention, it is obtained by mixing a rubber component, a polymer composition, and silica, and the polymer composition contains a polymer of a conjugated diene compound and / or an aromatic vinyl compound, and a nitrogen atom. And the weight average molecular weight of the polymer is 1.0 × 10 ^{3 to} 1.0 × 10 ⁴ , and the content of the organic compound in 100% by mass of the polymer composition is 0.1 to 10%. Since the rubber composition for tire is 20% by mass, the grip performance (particularly wet grip performance), wear resistance and rolling resistance characteristics can be improved in a well-balanced manner.

The tire rubber composition of the present invention is obtained by mixing a rubber component, a polymer composition, and silica, and the polymer composition is a polymer of a conjugated diene compound and / or an aromatic vinyl compound. , An organic compound having a nitrogen atom, and the weight average molecular weight of the polymer is 1.0 × 10 ^{3 to} 1.0 × 10 ⁴ , and the content of the organic compound in 100% by mass of the polymer composition is It is 0.1-20 mass%.

The polymer composition includes a specific amount of the polymer having a specific weight average molecular weight and an organic compound having a nitrogen atom. By kneading these components together with the rubber component and silica, the interaction with silica efficiently occurs during kneading, improving the dispersibility of silica, grip performance (especially wet grip performance), and abrasion resistance. In addition, rolling resistance characteristics (low fuel consumption) can be improved in a well-balanced manner.

<Polymer composition>
First, the polymer composition will be described.
The polymer composition is characterized in that it contains a specific amount of an organic compound having a nitrogen atom together with the polymer having a specific weight average molecular weight. As a method for producing the polymer composition, the organic compound may be added before the polymerization reaction of the polymer, during the polymerization reaction, and / or after the completion of the polymerization reaction. For example, the organic compound is polymerized after the polymer is polymerized. Examples thereof include a method of adding a compound, a method of polymerizing the polymer using the organic compound as a randomizer in a polymerization reaction, and leaving the organic compound together with the polymer. In the following, first, the organic compound and the polymer will be described.

（式（Ｉ）中、Ｒ^１は、ｎ価の炭素数１〜３０の炭化水素基を表す。Ｒ^２及びＲ^３は、同一若しくは異なって、水素原子、分岐若しくは非分岐の炭素数１〜３０のアルキル基、分岐若しくは非分岐の炭素数２〜３０のアルケニル基、分岐若しくは非分岐の炭素数２〜３０のアルキニル基、分岐若しくは非分岐の炭素数６〜３０のアリール基を表す。Ｒ^２とＲ^３とで環構造を形成してもよい。ｎは、１〜４の整数を表す。） (Organic compounds having nitrogen atoms)
As the organic compound having a nitrogen atom, amines are preferable. Examples of amines include monoamines, diamines, and triamines. Of these, compounds represented by the following formula (I) are preferred.

(In formula (I), R ¹ represents an n-valent hydrocarbon group having 1 to 30 carbon atoms. R ² and R ³ are the same or different and each represents a hydrogen atom, branched or unbranched carbon atoms having 1 to 30 carbon atoms. 30 alkyl groups, branched or unbranched alkenyl groups having 2 to 30 carbon atoms, branched or unbranched alkynyl groups having 2 to 30 carbon atoms, and branched or unbranched aryl groups having 6 to 30 carbon atoms. ² and R ³ may form a ring structure, and n represents an integer of 1 to 4.)

N ¹ valent carbon number of R ¹ (preferably 1 to 25 carbon atoms, more preferably 1 to 20 carbon atoms, still more preferably 1 to 10 carbon atoms, particularly preferably 1 to 5 carbon atoms, most preferably The hydrocarbon group having 1 to 3 carbon atoms is not particularly limited. For example, if it is a monovalent hydrocarbon group, the same groups as those described above for R ² and R ³ (excluding hydrogen atoms) may be mentioned. A divalent hydrocarbon group, a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched C 2-30 alkenylene group, a branched or unbranched carbon group having 2 to 30 carbon atoms. Alkynylene groups, branched or unbranched arylene groups having 6 to 30 carbon atoms, and the like. R ¹ is preferably a divalent hydrocarbon group, and more preferably a branched or unbranched alkylene group having 1 to 30 carbon atoms.

Branched or unbranched C1-30 (preferably C1-25, more preferably C1-20, even more preferably C1-10, particularly preferably C1-5, most preferably carbon Examples of the alkylene group of formulas 1 to 3 include, for example, a methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, dodecylene group, Examples include tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, octadecylene group and the like.

R ² and R ³ branched or unbranched 1 to 30 carbon atoms (preferably 1 to 25 carbon atoms, more preferably 1 to 20 carbon atoms, still more preferably 1 to 10 carbon atoms, particularly preferably 1 to 1 carbon atoms). 5, most preferably as the alkyl group having 1 to 3 carbon atoms, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, iso-butyl group, sec-butyl group, tert- Examples include butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, octadecyl group and the like.

R ² and R ³ branched or unbranched 2 to 30 carbon atoms (preferably 2 to 25 carbon atoms, more preferably 2 to 20 carbon atoms, still more preferably 2 to 10 carbon atoms, particularly preferably 2 to 2 carbon atoms). Examples of the alkenyl group of 5) include a vinyl group, 1-propenyl group, 2-propenyl group, 1-butenyl group, 2-butenyl group, 1-pentenyl group, 2-pentenyl group, 1-hexenyl group, 2- A hexenyl group, 1-octenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, octadecenyl group and the like can be mentioned.

R ² and R ³ branched or unbranched 2 to 30 carbon atoms (preferably 2 to 25 carbon atoms, more preferably 2 to 20 carbon atoms, still more preferably 2 to 10 carbon atoms, particularly preferably 2 to 2 carbon atoms). Examples of the alkynyl group of 5) include an ethynyl group, a propynyl group, a butynyl group, a pentynyl group, a hexynyl group, a heptynyl group, an octynyl group, a nonynyl group, a decynyl group, an undecynyl group, and the like.

Examples of the branched or unbranched aryl group having 6 to 30 carbon atoms (preferably 6 to 10 carbon atoms) of R ² and R ³ include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a biphenyl group. It is done.

The R ² and R ^3, a hydrogen atom, a branched or unbranched alkyl group having 1 to 30 carbon atoms and preferably, the alkyl group is more preferable. It is also preferred that the alkyl group forms a ring structure. In this case, the ring structure preferably has 3 to 7 carbon atoms.

n represents an integer of 1 to 4, but n is preferably 1 to 3 and more preferably 2 because the effect of the present invention can be more suitably obtained.

Among the compounds represented by the formula (I), examples of the monoamines include the following compounds. Primary monoamines include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, penta Saturated or unsaturated linear or branched aliphatic primary monoamines such as decylamine, hexadecylamine, heptadecylamine, octadecylamine, nonadecylamine; cyclohexylamine, 4-methylcyclohexylamine, 4-ethylcyclohexylamine And alicyclic primary monoamines such as 4-propylcyclohexylamine and 4-butylcyclohexylamine; and aromatic primary monoamines such as arinin and benzylamine. Secondary monoamines include aliphatic secondary monoamines such as N-methylhexylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine; bis (4-biphenylyl) amine, bis (4- Bromophenyl) amine, bis (4-t-butylphenyl) amine, bis (4-iodophenyl) amine, bis (4-nitrophenyl) amine, 3-chlorodiphenylamine, 4,4′-dimethoxydiphenylamine, 2,4 -Dimethyldiphenylamine, 3,4-dimethyldiphenylamine, 1,1'-dinaphthylamine, 2,2'-dinaphthylamine, 1,2'-dinaphthylamine, 3-methoxydiphenylamine, 4-methoxydiphenylamine, 3-methyldiphenylamine, 4-Methyldiphe Ruamine, m, m′-ditolylamine, p, p′-ditolylamine, N-phenyl-1-biphenylamine, N-phenyl-2-biphenylamine, N-phenyl-3-biphenylamine, N-phenyl-4-biphenyl Aromatic secondary monoamines such as amine, N- (p-tolyl) -1-naphthylamine, N- (p-tolyl) -2-naphthylamine and the like can be mentioned. Tertiary monoamines include trimethylamine and triethylamine. Of the monoamines, tertiary monoamines such as trimethylamine are preferred.

Among the compounds represented by the formula (I), examples of the diamines include the following compounds. Aliphatic diamines include ethylene diamine, trimethylene diamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, undecamethylene diamine, dodecamethylene diamine, Aliphatic primary diamines such as 1,3-bis (3-aminopropyl) tetramethyldisiloxane; N, N′-dimethylethylenediamine, N, N′-dimethylpropylenediamine, N, N′-diethyltetramethylene Aliphatic secondary diamines such as diamine, N, N′-dimethylhexamethylenediamine, N, N′-diethyldecamethylenediamine; N, N, N ′, N′-tetramethylmethylenediamine, N, N, N ', N'-Te Lamethylethylenediamine, N, N, N ′, N′-tetramethylpropylenediamine, N, N, N ′, N′-tetramethylbutylenediamine, N, N, N ′, N′-tetramethylheptylenediamine N, N, N ′, N′-tetramethyldodecylenediamine, N, N, N ′, N′-tetramethylheptadecylenediamine, N, N, N ′, N′-tetraethylmethylenediamine, N , N, N ′, N′-tetraethylethylenediamine, N, N, N ′, N′-tetraethylpropylenediamine, N, N, N ′, N′-tetraethylbutylenediamine, N, N, N ′, N′— Tetraethylheptylenediamine, N, N, N ′, N′-tetraethyldodecylenediamine, N, N, N ′, N′-tetraethylheptadecylenediamine, N, N, N ′, '-Tetrapropylmethylenediamine, N, N, N', N'-tetrapropylethylenediamine, N, N, N ', N'-tetrapropylpropylenediamine, N, N, N', N'-tetrapropylbutylenediamine N, N, N ′, N′-tetrapropylheptylenediamine, N, N, N ′, N′-tetrapropyldodecylenediamine, N, N, N ′, N′-tetrapropylheptadecylene Amine, N, N, N ′, N′-tetramethyl-1,3-propanediamine, 1,2-dipiperidinoethane, 1,2-dipiperidinopropane, 1,2-dipyrrolidinoethane Aliphatic tertiary diamines such as 1,2-dipyrrolidinobutane, and the like. The alicyclic diamines include 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1,2-di (aminomethyl) cyclohexane, 1,3-di (aminomethyl) cyclohexane. 1,4-di (aminomethyl) cyclohexane, 1-amino-2-aminomethylcyclohexane, 1-amino-3-aminomethylcyclohexane, 1-amino-4-aminomethylcyclohexane, 4,4′-methylenebis (cyclohexyl) Amine), 4,4′-methylenebis (2-methylcyclohexylamine), and the like. Aromatic diamines include o, m, p-phenylenediamine, tolylenediamine, xylenediamine, benzidine, dimethylbenzidine, diaminodiphenylmethane, 3-aminobenzylamine, 4-aminobenzylamine, 2,2-bis (3 -Amino-4-hydroxyphenyl) hexafluoropropane, 2,2-bis (3-amino-4-methylphenyl) hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis ( 4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] Propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropyl Bread, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, 1,1-bis (4-aminophenyl) cyclohexane, 9,9-bis (4 -Aminophenyl) fluorene, 2,2-bis (4-aminophenyl) hexafluoropropane, 2,2-bis (3-aminophenyl) hexafluoropropane, 1,3-bis [2- (4-aminophenyl) -2-propyl] benzene, bis (2-aminophenyl) sulfide, bis (4-aminophenyl) sulfide, bis (3-aminophenyl) sulfone, bis (4-aminophenyl) sulfone, 2,2′-bis ( Trifluoromethyl) benzidine, 4,4′-diaminobenzophenone, 3,3′-diaminobenzophenone, 4,4 ′ Diamino-3,3′-dimethyldiphenylmethane, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 2,7-diaminofluorene, 1,5-diaminonaphthalene, 4,4′-diaminooctafluorobiphenyl, 2,5-dimethyl-1,4-phenylenediamine, 4,4′-ethylenedianiline, 4,4 ′ Aromatic groups such as methylenebis (2,6-diethylaniline), 4,4′-methylenebis (2-ethyl-6-methylaniline), 2,3,5,6-tetramethyl-1,4-phenylenediamine, etc. Primary diamines; N, N′-dimethyl-phenylenediamine, N, N′-dimethyl-xy Lylenediamine, N, N′-dimethyl-benzidine, N, N′-dimethyl-1,4-naphthalenediamine, N, N′-di-2-naphthyl-1,4-phenylenediamine, N, N′-diphenyl- Aromatic secondary diamines such as 1,4-phenylenediamine, N, N′-diphenylbenzidine, N, N′-di-p-tolylbenzidine; and the like. These amines may be used alone or in combination of two or more. Among the diamines, aliphatic tertiary diamines such as N, N, N ′, N′-tetramethylethylenediamine and 1,2-dipiperidinoethane are preferable.

(Polymer of conjugated diene compound and / or aromatic vinyl compound)
As a polymer of a conjugated diene compound and / or an aromatic vinyl compound, a conjugated diene compound and an aromatic vinyl compound are preferable because good grip performance (particularly wet grip performance), wear resistance, and rolling resistance characteristics can be obtained. Of these, preferred is a styrene butadiene copolymer.

Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene, and the like. These may be used alone or in combination of two or more. Among these, 1,3-butadiene and isoprene are preferable from the viewpoint of practical use such as availability of monomers, 3-butadiene is more preferred.

Examples of the aromatic vinyl compound include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, 2,4,6-trimethylstyrene, and the like. These may be used alone or in combination of two or more. Among these, styrene is particularly preferable from the viewpoint of practical use such as availability of monomers.

In addition, a butadiene homopolymer is obtained by using 1,3-butadiene, a styrene homopolymer is obtained by using styrene, and a styrene-butadiene copolymer is obtained by using 1,3-butadiene and styrene. It is done.

The polymer is obtained, for example, by polymerizing a conjugated diene compound and / or an aromatic vinyl compound. In addition, you may perform a hydrogenation process to a polymer as needed. Specifically, the polymer can be synthesized by the following method.

There is no restriction | limiting in particular as a method of superposing | polymerizing a conjugated diene compound and / or an aromatic vinyl compound, A conventionally well-known method can be used. Specifically, in an organic solvent inert to the reaction, for example, a hydrocarbon solvent such as an aliphatic, alicyclic or aromatic hydrocarbon compound, a conjugated diene compound and / or an aromatic vinyl compound is converted into an organolithium compound. As a polymerization initiator, there may be mentioned a method of anionic polymerization in the presence of a randomizer, if necessary.

The hydrocarbon solvent is not particularly limited, but is preferably one having 3 to 8 carbon atoms, such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, Examples thereof include trans-2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, and ethylbenzene.

As the organic lithium compound, those having an alkyl group having 2 to 20 carbon atoms are preferable, for example, ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, tert-octyl. Examples include lithium, n-decyl lithium, phenyl lithium, 2-naphthyl lithium, 2-butyl-phenyl lithium, 4-phenyl-butyl lithium, cyclohexyl lithium, cyclopentyl lithium, reaction products of diisopropenylbenzene and butyl lithium, and the like. Of these, n-butyllithium or sec-butyllithium is preferable from the viewpoints of availability and safety.

The randomizer is a microstructure control of a conjugated diene moiety in a copolymer (for example, an increase in 1,2-bonds in butadiene, etc.) and a control of the composition distribution of monomer units in the copolymer (for example, butadiene). -A compound having an action such as a butadiene unit in a styrene copolymer or randomization of a styrene unit. The randomizer is not particularly limited, and any known compound generally used as a conventional randomizer can be used. For example, dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, bistetrahydrofurylpropane, triethylamine, pyridine, N-methylmorpholine, N, N, N ′, N′-tetramethylethylenediamine, 1,2-di Examples include ethers such as piperidinoethane and tertiary amines. Further, potassium salts such as potassium-t-amylate and potassium-t-butoxide, and sodium salts such as sodium-t-amylate can also be used.

The amount of the randomizer used varies depending on the type of randomizer used, but is preferably 0.01 molar equivalents or more, more preferably 0.05 molar equivalents or more per mole of the polymerization initiator. If the amount of randomizer used is less than 0.01 molar equivalent, the effect of addition tends to be small, and randomization tends to be difficult. The amount of randomizer used is preferably 1000 molar equivalents or less, more preferably 500 molar equivalents or less per mole of the polymerization initiator. When the amount of the randomizer used exceeds 1000 molar equivalents, the monomer reaction rate changes greatly, and conversely, it tends to be difficult to randomize.
In the case where an organic compound having a nitrogen atom is used as the randomizer and the compound remains in the polymer composition, the amount of randomizer used should be determined in consideration of the amount to be retained. Just decide.

There is no particular limitation on the polymerization method, and any of solution polymerization method, gas phase polymerization method and bulk polymerization method can be used, but the solution polymerization method is particularly preferable from the viewpoint of the degree of freedom in polymer design and processability. preferable. Moreover, any of a batch type and a continuous type may be sufficient as the superposition | polymerization form.

When the solution polymerization method is used, the monomer concentration in the solution (the total of the conjugated diene compound, aromatic vinyl compound, etc.) is preferably 5% by mass or more, more preferably 10% by mass or more. When the monomer concentration in the solution is less than 5% by mass, the amount of the copolymer obtained is small and the cost tends to be high. The monomer concentration in the solution is preferably 50% by mass or less, more preferably 30% by mass or less. If the monomer concentration in the solution exceeds 50% by mass, the solution viscosity becomes too high, stirring becomes difficult, and polymerization tends to be difficult.

As described above, the polymer may be hydrogenated. In that case, after the polymerization reaction, the obtained polymer may be further subjected to a hydrogenation treatment to prepare a hydrogenated polymer.

The hydrogenation treatment can be carried out by a known hydrogenation method. For example, a known hydrogenation catalyst (homogeneous hydrogenation catalyst, heterogeneous hydrogenation catalyst, etc.) is used, and the treatment is performed under pressurized hydrogen at 1 to 100 atm. For example, the polymer can be hydrogenated.

Usually, water, alcohol, acid or the like is mixed for the purpose of stopping the polymerization reaction. Furthermore, you may mix a well-known anti-aging agent as needed.

The weight average molecular weight (Mw) of the polymer is 1.0 × 10 ³ or more, preferably 1.2 × 10 ³ or more, more preferably 1.4 × 10 ³ or more. When Mw is less than 1.0 × 10 ³ , not only is the hysteresis loss large and sufficient rolling resistance characteristics are difficult to obtain, but also the wear resistance is reduced. The Mw is 1.0 × 10 ⁴ or less, preferably 5.0 × 10 ³ or less, more preferably 2.0 × 10 ³ or less. When Mw exceeds 1.0 × 10 ⁴ , there is a concern about deterioration of workability.
In addition, in this specification, a weight average molecular weight (Mw) is measured by the method as described in the below-mentioned Example. Moreover, Mw can be suitably adjusted by methods, such as changing the quantity of the polymerization initiator used at the time of superposition | polymerization.

The styrene content of the polymer is preferably 0.1% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, particularly preferably 20% by mass or more, and most preferably 30% by mass or more. . If the styrene content is less than 0.1% by mass, sufficient grip performance may not be obtained. The styrene content is preferably 55% by mass or less, more preferably 50% by mass or less. When the styrene content exceeds 55% by mass, rolling resistance characteristics and wear resistance tend to deteriorate.
In addition, in this specification, styrene content is measured by the method as described in the below-mentioned Example.

As a method for producing the polymer composition, the organic compound may be added before the polymerization reaction of the polymer, during the polymerization reaction, and / or after the completion of the polymerization reaction. For example, as described above, A method of adding the organic compound after polymerization, or using the organic compound as a randomizer used during the polymerization (polymerizing the polymer using the organic compound as a randomizer in a polymerization reaction) Examples thereof include a method of leaving the organic compound together with the coalescence.
Specifically, after completion of the polymerization reaction, an organic compound having a nitrogen atom is mixed with the polymer obtained by removing the solvent, randomizer, etc. by purification operations such as reprecipitation purification and drying under reduced pressure. By doing so, a polymer composition can be obtained. In addition, when an organic compound having a nitrogen atom is used as a randomizer, the polymer is removed by removing the solvent by drying under reduced pressure (that is, not purifying and removing the remaining organic compound having a nitrogen atom). A composition can be obtained. The randomizer can be added either before or during the polymerization reaction.

Content of the organic compound which has a nitrogen atom in 100 mass% of polymer compositions is 0.1 mass% or more, Preferably it is 1 mass% or more, More preferably, it is 3 mass% or more. If it is less than 0.1% by mass, the rolling resistance characteristics and wet grip performance cannot be sufficiently improved.
Moreover, this content is 20 mass% or less, Preferably it is 18 mass% or less, More preferably, it is 16 mass% or less, More preferably, it is 12 mass% or less, Most preferably, it is 10 mass% or less. If it exceeds 20% by mass, the scorch time is shortened and the cost is increased.

In the rubber composition of the present invention, the content of the polymer composition is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and still more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. . If it is less than 3 parts by mass, rolling resistance characteristics, wear resistance, and grip performance may not be sufficiently improved. The content is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and still more preferably 25 parts by mass or less. If the amount exceeds 40 parts by mass, the rolling resistance characteristics deteriorate and the cost tends to increase.
In the rubber composition of the present invention, the polymer composition is not included in the rubber component.

Examples of rubber components that can be used in the present invention include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber ( IIR) and diene rubbers such as styrene-isoprene-butadiene copolymer rubber (SIBR). A rubber component may be used independently and may be used in combination of 2 or more type. Of these, NR, BR, and SBR are preferable because grip performance, wear resistance, and rolling resistance characteristics are well-balanced, and a combination of NR, BR, and SBR is more preferable.

The NR is not particularly limited, and for example, those commonly used in the tire industry such as SIR20, RSS # 3, TSR20, and the like can be used.

The content of NR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 15% by mass or more, and preferably 35% by mass or less, more preferably 25% by mass or less. Within the above range, grip performance, wear resistance, and rolling resistance characteristics can be obtained in a well-balanced manner.

It is not particularly limited as BR, for example, BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B manufactured by Ube Industries, Ltd., BR150B having high cis content such as BR150B, VCR412 manufactured by Ube Industries, Ltd., VCR617, etc. BR containing syndiotactic polybutadiene crystals can be used. Of these, the BR cis content is preferably 90% by mass or more because of its good wear resistance.

The content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 15% by mass or more, and preferably 35% by mass or less, more preferably 25% by mass or less. Within the above range, grip performance, wear resistance, and rolling resistance characteristics can be obtained in a well-balanced manner.

The SBR is not particularly limited, and for example, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR), and the like can be used. Among these, S-SBR is preferable from the viewpoint that rolling resistance characteristics and wear resistance can be improved satisfactorily.

The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more. Moreover, this styrene content becomes like this. Preferably it is 50 mass% or less, More preferably, it is 30 mass% or less, More preferably, it is 20 mass% or less. When the styrene content is within the above range, good rolling resistance characteristics and wear resistance can be obtained.

The content of SBR in 100% by mass of the rubber component is preferably 35% by mass or more, more preferably 45% by mass or more, and preferably 85% by mass or less, more preferably 75% by mass or less, still more preferably. 65% by mass or less. Within the above range, grip performance, wear resistance, and rolling resistance characteristics can be obtained in a well-balanced manner.

Examples of the silica include dry process silica (anhydrous silicic acid), wet process silica (hydrous silicic acid), and the like, but wet process silica is preferred because it has many silanol groups.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 50 m ² / g or more, more preferably 80 m ² / g or more, and still more preferably 150 m ² / g or more. If it is less than 50 m < ² > / g, there exists a tendency for a reinforcement effect to be small and sufficient abrasion resistance not to be acquired. Further, the _N 2 SA is preferably from 300 meters ² / g or less, more preferably ^{250m 2 / g, 200m 2 /} g or less is more preferable. When it exceeds 300 m ² / g, the dispersibility of the silica is poor, the hysteresis loss increases, and the rolling resistance characteristic tends to decrease.
The _N 2 SA of silica is a value determined by the BET method in accordance with ASTM D3037-93.

In the rubber composition of the present invention, the content of silica is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 30 parts by mass or more, and particularly preferably 50 parts by mass with respect to 100 parts by mass of the rubber component. More than part by mass. If the amount is less than 5 parts by mass, the reinforcing property is small, so that sufficient wear resistance tends to be not obtained. In addition, sufficient rolling resistance characteristics tend not to be obtained. The content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less. When it exceeds 150 parts by mass, workability and dispersibility are poor, and wear resistance and rolling resistance characteristics tend to be deteriorated.

The rubber composition of the present invention preferably contains a silane coupling agent together with silica. Examples of the silane coupling agent include sulfide, mercapto, vinyl, amino, glycidoxy, nitro, and chloro silane coupling agents. These may be used alone or in combination of two or more. Of these, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, bis (2 Sulfide systems such as -triethoxysilylethyl) disulfide can be preferably used.

The content of the silane coupling agent is preferably 1 part by mass or more, more preferably 4 parts by mass or more with respect to 100 parts by mass of silica. If it is less than 1 part by mass, the viscosity of the unvulcanized rubber composition tends to be high and the processability tends to deteriorate. The content is preferably 20 parts by mass or less, more preferably 12 parts by mass or less. If it exceeds 20 parts by mass, the blending effect of the silane coupling agent as much as the blending amount cannot be obtained, and the cost tends to increase.

In the present invention, it is preferable to blend carbon black. Thereby, abrasion resistance and grip performance can be improved more suitably.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 30 m ² / g or more, and more preferably 70 m ² / g or more. If it is less than 30 m ² / g, sufficient reinforcing properties cannot be obtained, and sufficient abrasion resistance and wet grip performance may not be obtained. The _N 2 SA is preferably 250 meters ² / g less, more preferably not more than 150 meters ² / g, more preferably not more than 120 m ² / g. When it exceeds 250 m ² / g, heat generation increases, and the rolling resistance characteristics tend to deteriorate.
Incidentally, _N 2 SA of carbon black, JIS K 6217-2: determined by 2001.

Carbon black has a dibutyl phthalate oil absorption (DBP) of preferably 50 ml / 100 g or more, and more preferably 100 ml / 100 g or more. If it is less than 50 ml / 100 g, sufficient reinforcing properties cannot be obtained, and sufficient abrasion resistance and wet grip performance may not be obtained. The DBP of carbon black is preferably 200 ml / 100 g or less, and more preferably 135 ml / 100 g or less. When it exceeds 200 ml / 100 g, the heat generation becomes large and the rolling resistance characteristics tend to deteriorate.
The DBP of carbon black is measured according to JIS K6217-4: 2001.

The content of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 1 part by mass, sufficient reinforcement may not be obtained. The content of carbon black is preferably 30 parts by mass or less, more preferably 10 parts by mass or less. When it exceeds 30 mass parts, there exists a tendency for rolling resistance characteristics to deteriorate.

In addition to the above components, the rubber composition of the present invention contains compounding agents commonly used in the production of rubber compositions such as oil, various anti-aging agents, stearic acid, zinc oxide, vulcanizing agents, and vulcanization acceleration. An agent or the like can be appropriately blended.

The rubber composition of the present invention can be produced by a general method. That is, the above components (at least the rubber component, the polymer composition, and silica) are kneaded with a known kneader used in a general rubber industry such as a Banbury mixer, a kneader, or an open roll, and then added. It can be manufactured by a method of sulfurating. For example, it can be suitably obtained by a production method including a step of mixing a rubber component, a polymer composition, silica, and other components that are appropriately added as necessary, and a step of adding and mixing a vulcanizing agent. . In the production method, the components may be mixed at a time or in any order.

Specifically, a rubber component, a polymer composition, silica and the like are kneaded at 120 to 180 ° C. (preferably 130 to 175 ° C.) for 1 to 20 minutes (preferably 2 to 10 minutes), and then sulfur and the like. The vulcanizing agent and the vulcanization accelerator are added, kneaded at 50 to 90 ° C. (preferably 70 to 85 ° C.) for 1 to 20 minutes (preferably 2 to 10 minutes), and then vulcanized. The rubber composition can be produced.

The rubber composition of the present invention can be suitably used for each member of a tire, but a tread and a sidewall are more preferable, and a tread is more preferable because of a large contribution to rolling resistance characteristics.

The pneumatic tire of the present invention can be produced by a usual method using the rubber composition. That is, a rubber composition containing the above components is extruded in accordance with the shape of each member of the tire at an unvulcanized stage, and is molded together with other tire members by a normal method on a tire molding machine. Thus, an unvulcanized tire is formed. A tire is obtained by heating and pressurizing the unvulcanized tire in a vulcanizer.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Hereinafter, in the production examples, various chemicals used during synthesis and polymerization will be described together. In addition, the chemical | medical agent refine | purified according to the usual method as needed.
n-hexane: Kanto Chemical Co., Ltd. Styrene: Kanto Chemical Co., Ltd. 1,3-Butadiene: Tokyo Chemical Industry Co., Ltd. Tetramethylethylenediamine: Kanto Chemical Co., Ltd. n-Butyllithium: Kanto Chemical Co., Ltd. 1.6M n-butyllithium hexane solution 2,6-di-t-butyl-p-cresol manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

Production Example 1 (Synthesis of Polymer (1) (Styrene Butadiene Copolymer))
To a heat-resistant container sufficiently purged with nitrogen, 36 L of n-hexane, 7.3 mol of styrene, 22 mol of 1,3-butadiene, 2.0 mol of tetramethylethylenediamine and 1.5 mol of n-butyllithium were added, and the mixture was stirred at 5 ° C. for 30 minutes. . Thereafter, alcohol was added to stop the reaction, and 1 g of 2,6-di-t-butyl-p-cresol was added to the reaction solution, followed by reprecipitation purification and drying under reduced pressure to obtain a polymer (1).

Production Example 2 (Preparation of polymer composition (1))
Polymers were synthesized in the same manner as in Production Example 1 using the recipe in Table 1. And after drying under reduced pressure, 0.1 mol of tetramethylethylenediamine was added and mixed to the obtained polymer, and the polymer composition (1) was obtained.

Production Example 3 (Preparation of polymer composition (2))
A polymer was synthesized in the same manner as in Production Example 1 using the recipe shown in Table 1 except that it was dried under reduced pressure without being reprecipitated and purified to obtain a polymer composition (2).

Production Example 4 (Preparation of polymer composition (3))
Except that the tetramethylethylenediamine of Production Example 2 was changed to 1,2-dipiperidinoethane, a polymer was synthesized in the same manner as in Production Example 2 using the recipe of Table 1, and a polymer composition (3 )

Production Example 5 (Preparation of polymer composition (4))
Except that the tetramethylethylenediamine of Production Example 3 was changed to 1,2-dipiperidinoethane, a polymer was synthesized in the same manner as in Production Example 3 using the recipe of Table 1, and a polymer composition (4 )

The following evaluation was performed about the obtained polymer (1) and polymer composition (1)-(4). The results are shown in Table 1. In addition, about polymer composition (1)-(4), styrene content and evaluation of a weight average molecular weight isolate | separate the polymer contained in polymer composition (1)-(4), and this polymer Was evaluated.

(Measurement of styrene content of polymer)
H ¹ -NMR was measured at 25 ° C. using a JEOL JNM-A 400 NMR apparatus, and phenyl protons based on 6.5 to 7.2 ppm styrene units and 4.9 to 5.4 ppm butadiene were obtained from the spectrum. The styrene content was determined from the ratio of vinyl protons based on units.

(Measurement of weight average molecular weight (Mw) of polymer)
The weight average molecular weight (Mw) of the polymer was determined by gel permeation chromatography (GPC) (GPC-8000 series, manufactured by Tosoh Corporation), detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation. ) Based on standard polystyrene conversion.

(Measurement of tetramethylethylenediamine content, 1,2-dipiperidinoethane content)
The content of tetramethylethylenediamine (1,2-dipiperidinoethane content) in 100% by mass of the polymer or polymer composition was determined by the deuterochloroform solution (40 mg / 1 mL CDCl3) of the polymer or polymer composition. ) And the peak area ratio was calculated using an AV400 apparatus manufactured by BRUKER.

<Examples and Comparative Examples>
Below, various chemical | medical agents used by the Example and the comparative example are demonstrated.
NR: RSS # 3
BR: Ubepol BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass)
SBR: SL574 manufactured by JSR Corporation (S-SBR, styrene content: 15% by mass)
Polymer (1): prepared by the above method Polymer compositions (1) to (4): prepared by the above method Silica: Ultrasil VN3 manufactured by Evonik Degussa (N ₂ SA: 175 m ² / g)
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Evonik Degussa
Carbon black: Dia Black N339 manufactured by Mitsubishi Chemical Corporation (N ₂ SA: 96 m ² / g, DBP absorption: 124 ml / 100 g)
Oil: X-140 manufactured by Japan Energy Co., Ltd.
Anti-aging agent: NOCRACK 6C (N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Stearic acid: Zinc stearate manufactured by NOF Corporation: Zinc Hua No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Co., Ltd.
Tetramethylethylenediamine: Sulfur manufactured by Kanto Chemical Co., Ltd .: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. (1): Noxeller CZ manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator (2): Noxeller D manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

According to the blending content shown in Table 2, materials other than sulfur and vulcanization accelerator were kneaded for 5 minutes at 150 ° C. using a 1.7 L Banbury mixer manufactured by Kobe Steel Co., Ltd. Obtained. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 5 minutes under the condition of 80 ° C. using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press vulcanized at 170 ° C. for 15 minutes to obtain a vulcanized rubber composition.
The obtained vulcanized rubber composition was evaluated as follows, and the results are shown in Table 2.

(Rolling resistance characteristics (low fuel consumption))
The obtained vulcanized rubber composition was measured for tan δ at a dynamic strain amplitude of 1%, a frequency of 10 Hz, and a temperature of 50 ° C. using a spectrometer manufactured by Ueshima Seisakusho. And the measurement result was displayed as an index according to the following formula. The larger the index, the smaller the rolling resistance and the better the rolling resistance characteristic (low fuel consumption).
(Rolling resistance index) = (tan δ of Comparative Example 1) / (tan δ of each formulation) × 100

(Wet grip performance)
Wet grip performance was evaluated using a flat belt friction tester (FR5010 type) manufactured by Ueshima Seisakusho. A cylindrical rubber test piece having a width of 20 mm and a diameter of 100 mm made of the above vulcanized rubber composition was used as a sample, and the slip ratio of the sample with respect to the road surface was 0 to 0 at a speed of 20 km / hour, a load of 4 kgf, and a road surface temperature of 20 ° C. The maximum value of the friction coefficient detected at that time was read up to 70%. And the measurement result was displayed as an index according to the following formula. A larger index indicates better wet grip performance.
(Wet grip performance index) = (maximum friction coefficient of each formulation) / (maximum friction coefficient of Comparative Example 1) × 100

(Abrasion resistance)
Using a Lambone-type wear tester, the Lambourne wear amount of the vulcanized rubber composition was measured under the conditions of room temperature, applied load of 1.0 kgf, and slip rate of 30%. The volume loss amount was calculated from the measured Lambourne wear amount, and the volume loss amount of Comparative Example 1 was taken as 100, and the volume loss amount of each formulation was indicated by an index according to the following formula. It shows that it is excellent in abrasion resistance, so that an index | exponent is large.
(Abrasion resistance index) = (volume loss amount of Comparative Example 1) / (volume loss amount of each formulation) × 100

From Table 2, obtained by mixing a rubber component, a polymer composition, and silica, the polymer composition is a polymer of a conjugated diene compound and / or an aromatic vinyl compound, and an organic compound having a nitrogen atom. The polymer has a weight average molecular weight of 1.0 × 10 ^{3 to} 1.0 × 10 ⁴ , and the content of the organic compound in 100% by mass of the polymer composition is 0.1 to 20 mass. %, The grip performance (particularly wet grip performance), wear resistance, and rolling resistance characteristics could be improved in a well-balanced manner.

Claims (7)

A method for producing a rubber composition for a tire, comprising:
Including a step of mixing a rubber component, a polymer composition, and silica;
The polymer composition comprises a polymer of a conjugated diene compound and / or an aromatic vinyl compound composed of a organic compound having a nitrogen atom, the weight average molecular weight of the polymer is 1.0 × 10 ³ to 1.0 × 10 ⁴ , the content of the organic compound in 100% by mass of the polymer composition is 0.1 to 20% by mass,
The organic compound is, Ri compound der represented by the following formula (I),
The polymer is a polymer of a conjugated diene compound, or a copolymer of a conjugated diene compound and an aromatic vinyl compound,
The method for producing a tire rubber composition, wherein in the tire rubber composition, a content of the polymer composition is 3 to 40 parts by mass with respect to 100 parts by mass of a rubber component .

(In the formula (I), R ¹ represents an n-valent hydrocarbon group having 1 to 30 carbon atoms. R ² and R ³ are the same or different and are branched or unbranched alkyl having 1 to 30 carbon atoms. And R ² and R ³ may form a ring structure, and n represents an integer of 2 to 4.) The method for producing a rubber composition for a tire according to claim 1, wherein the polymer composition is obtained by adding the organic compound before the polymerization reaction, during the polymerization reaction, and / or after the completion of the polymerization reaction. . The method for producing a rubber composition for a tire according to claim 1 or 2, wherein the polymer is a copolymer of a conjugated diene compound and an aromatic vinyl compound. The method for producing a tire rubber composition according to claim 1, wherein the polymer is a styrene-butadiene copolymer. The method for producing a rubber composition for a tire according to claim 4, wherein the styrene-butadiene copolymer has a styrene content of 0.1 to 55% by mass. In the rubber composition for a tire, the manufacturing method relative to 100 parts by mass of the rubber component, a tire rubber composition according to any one of claims 1 to 5 content before Symbol silica is 5 to 150 parts by weight . The process of producing a tire rubber composition using the manufacturing method of the rubber composition for tires in any one of Claims 1-6, and the process of producing a tire member using the produced rubber composition for tires The manufacturing method of the pneumatic tire containing these.