JP2008184517A - Rubber composition and pneumatic tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition suitable for a tread rubber of a high-performance pneumatic tire having good abrasion resistance and crashworthiness and providing excellent steering stability on a dry road. <P>SOLUTION: The rubber composition is obtained by compounding (B) 1-200 pts.mass modified hydrogenated polymer comprising an aromatic vinyl-conjugated diene copolymer containing one or more kinds of polar groups selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a carboxylate functional group and a sulfonate functional group in the molecule, and having 1.0×10<SP>3</SP>to 2.0×10<SP>5</SP>polystyrene-equivalent number average molecular weight and 20-100% hydrogenation rate of the conjugated diene part, and/or a conjugated diene polymer, and (C) 0.1-10 pts.mass compound containing zinc, with (A) 100 pts.mass matrix rubber comprising an aromatic vinyl-conjugated diene copolymer having 3.0×10<SP>5</SP>-3.0×10<SP>6</SP>polystyrene-equivalent weight average molecular weight obtained by a gel permeation chromatography and polymerized by using a lithium-based polymerization initiator, and/or a conjugated diene polymer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rubber composition suitable for a tread of a pneumatic tire and a pneumatic tire using the rubber composition. More specifically, the present invention has good wear resistance and fracture resistance, and excellent dry road handling stability. The present invention relates to a rubber composition suitable for tread rubber of a pneumatic tire and a pneumatic tire using the rubber composition in a tread portion.

High tread rubber for tires that are required to travel at high speeds requires high dry road handling stability (dry grip performance). Conventionally, in order to obtain high dry road handling stability, a method using a styrene-butadiene copolymer rubber (SBR) having a high styrene component content, a method of making a blending system highly filled with a softener and carbon black, The method of using carbon black with small particles was taken.
However, in general, SBR with a high amount of bound styrene has a high glass transition temperature (Tg), so that the temperature dependence of the physical properties of the rubber composition increases in the vicinity of the tire temperature during running, and the performance changes with respect to temperature changes. There was a problem of becoming larger.

In order to improve this point, it has been proposed to add a low molecular weight SBR to the SBR matrix rubber. However, even though the molecular weight is low, it has many crosslinkable double bonds. However, there is a problem that a sufficient hysteresis loss is not generated due to formation of a crosslink with the matrix rubber and incorporation into the matrix. (See Patent Document 1)
However, in recent years, there has been an increasing demand for high-performance tires for better dry road handling stability and wear resistance.

JP 63-101440 A

  The subject of this invention is providing the rubber composition suitable for the tread rubber of a high performance pneumatic tire which is excellent in abrasion resistance and destruction resistance, and is excellent in dry road steering stability.

As a result of intensive studies in order to achieve the above-mentioned problems, the present inventors have added hydrogen having a specific molecular weight to a matrix rubber made of an aromatic vinyl-conjugated diene copolymer and / or a conjugated diene polymer. A specific amount of a modified hydrogenated polymer containing a carboxylic acid group and a sulfonic acid group or a salt functional group thereof in a molecule of the aromatic vinyl-conjugated diene copolymer and / or conjugated diene polymer and a specific metal compound and / or amine It has been found that by adding a specific amount of the compound, the compatibility between the matrix rubber and the hydrogenated modified hydrogenated polymer can be improved, thereby improving the dry road handling stability, wear resistance and fracture resistance. It was. The present invention has been completed based on such findings.
That is, the present invention
[1] Aromatic vinyl-conjugated diene copolymer polymerized with a lithium-based polymerization initiator, having a polystyrene equivalent weight average molecular weight of 3.0 × 10 ^{5 to} 3.0 × 10 ⁶ obtained by gel permeation chromatography And / or one or more selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a carboxylate functional group and a sulfonate functional group with respect to 100 parts by mass of the matrix rubber (A) made of a conjugated diene polymer. Aromatic vinyl-conjugated having a polar group in the molecule, a polystyrene-equivalent number average molecular weight of 1.0 × 10 ^{3 to} 2.0 × 10 ⁵ , and a hydrogenation rate of the conjugated diene part of 20 to 100% A rubber composition comprising 1 to 200 parts by mass of a modified hydrogenated polymer (B) comprising a diene copolymer and / or a conjugated diene polymer and 0.1 to 10 parts by mass of a compound (C) containing zinc.
[2] The rubber composition of the above (1), wherein the matrix rubber (A) is a styrene-butadiene copolymer,
[3] The rubber composition according to the above (2), wherein the matrix rubber (A) has a styrene-butadiene copolymer having a bound styrene content of 20 to 40% by mass,
[4] Matrix rubber (A) The rubber composition according to the above (2), wherein the butadiene portion of the styrene-butadiene copolymer has a vinyl bond content of 30 to 60%.
[5] The rubber composition according to any one of (1) to (4) above, wherein 1 to 200 parts by mass of carbon black is further added to 100 parts by mass of the matrix rubber (A).
[6] The rubber composition according to any one of the above (1) to (5), wherein the amount of bound styrene of the modified hydrogenated polymer (B) is 0 to 60% by mass,
[7] The rubber composition according to any one of (1) to (6) above, wherein 10 to 100 parts by mass of the modified hydrogenated polymer (B) is blended with 100 parts by mass of the matrix rubber (A).
[8] The rubber composition according to any one of (1) to (7), wherein the modified hydrogenated polymer (B) has a polystyrene-equivalent number average molecular weight of 1.0 × 10 ³ or more and less than 2.0 × 10 ⁴ .
[9] The modified hydrogenated polymer (B) is selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a carboxylate functional group and a sulfonate functional group at one or both ends of the molecular chain. The rubber composition according to any one of the above (1) to (8), comprising a polar group

[10] The rubber composition according to any one of (1) to (9), wherein the carboxylate functional group contains a metal ion and / or a quaternary ammonium ion,
[11] The rubber composition according to any one of (1) to (10), wherein the sulfonate functional group contains a metal ion and / or a quaternary ammonium ion,
[12] The metal ions are Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Al ³⁺ , Zn ²⁺ , Cu ²⁺ , Mn ^2+. The rubber composition according to (10) or (11), wherein the rubber composition is an ion selected from at least one selected from the group consisting of Ni ²⁺ , Co ²⁺ , Co ³⁺ , Fe ³⁺ and Cr ³⁺ .
[13] A quaternary ammonium ion is represented by the general formula (I)
NH _m R ¹ _n ⁺ (I)
(Wherein m + n = 4, m = 0-4, R ¹ is an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 120 carbon atoms or an aralkyl group) (10) ) Or (11) rubber composition,
[14] The rubber composition according to any one of (1) to (13), wherein the zinc-containing compound (C) is zinc oxide,
[15] Further, a metal compound containing a metal selected from the group consisting of Li, Na, Rb, Cs, Mg, Ca, Sr, Ba, Al, Cu, Mn, Ni, Co, Fe, and Cr (D) and / or the rubber composition according to any one of (1) to (14) above, wherein 0 to 60 parts by mass of the amine compound (E) is blended,
[16] The metal compound (D) is a metal oxide, metal hydroxide, metal acetate, general formula (II)
R ² SO ₃ · 1 / pM (II)
(Wherein R ² is an alkyl group having 1 to 20 carbon atoms, or an aryl group or aralkyl group having 6 to 120 carbon atoms, M is a metal, and p is a valence of M) and / Or general formula (III)
M (OR ³ ) _p (III)
(Wherein R ³ is an alkylate having 1 to 20 carbon atoms, or an aryl or aralkyl group having 6 to 120 carbon atoms, M is a metal, and p is a valence of M) 15) a rubber composition,
[17] The amine compound (E) is represented by the general formula (IV):
NH _q R ⁴ _r (IV)
(Wherein q + r = 3, q = 0-3, and R ⁴ is an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 120 carbon atoms, or an aralkyl group) (15 ) Rubber composition,
[18] The rubber composition according to any one of (15) to (17), wherein the metal compound (D) and / or the amine compound (E) is blended in any of the kneading step, the non-pro kneading step, and the pro kneading step. ,as well as
[19] A pneumatic tire using the rubber composition according to any one of (1) to (18) in a tread portion,
Is to provide.

  According to the present invention, it is possible to provide a rubber composition suitable for a tread rubber of a high-performance pneumatic tire that has good wear resistance and fracture resistance and remarkably improved dry road handling stability.

In the present invention, an aromatic vinyl-conjugated diene copolymer and / or a conjugated diene polymer polymerized with a lithium polymerization initiator is used as the matrix rubber (A).
Here, the polystyrene equivalent weight average molecular weight obtained by gel permeation chromatography (GPC) of the matrix rubber (A) is defined as 3.0 × 10 ^{5 to} 3.0 × 10 ⁶ , which is If it is less than 3.0 × 10 ⁵ , the wear resistance and fracture resistance are lowered, and if it exceeds 3.0 × 10 ⁶ , the viscosity of the polymerization solution is increased and the productivity is lowered. From the same viewpoint, it is preferably 7.0 × 10 ^{5 to} 2.5 × 10 ⁶ .

The above matrix rubber (A) is, for example, a conjugated diene monomer alone or a conjugated diene monomer and an aromatic vinyl hydrocarbon monomer in a hydrocarbon solvent in the presence of an ether or a tertiary amine. It is obtained by polymerizing or copolymerizing with a lithium polymerization initiator.
Examples of the conjugated diene monomer include butadiene (1,3-butadiene), isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene, and the like. Butadiene is preferred.
Examples of aromatic vinyl hydrocarbon monomers include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, 1-2,4,6-trimethylstyrene. Etc., and styrene is preferable. Any of the conjugated diene monomer and the aromatic vinyl hydrocarbon monomer may be used alone or in combination of two or more.

As described above, the matrix rubber (A) is preferably a styrene-butadiene copolymer (hereinafter sometimes referred to as SBR). In this case, the amount of bound styrene of the matrix rubber (A) is 20 to 40% by mass. Is preferred. This is because if it is 20% by mass or more, the dry road handling stability and fracture resistance are improved, and if it is 40% by mass or less, the wear resistance becomes better.
Furthermore, when the matrix rubber (A) is SBR, the vinyl bond content in the butadiene portion is preferably 30 to 60%. This is because if it is 30% or more, the dry road handling stability is further improved, and if it is 60% or less, the wear resistance is further improved.

  Examples of the hydrocarbon solvent include alicyclic hydrocarbons such as cyclohexane, methylcyclopentane, and cyclooctane; aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, and decane; benzene, toluene, ethylbenzene, and the like. Aromatic hydrocarbons can be used. These hydrocarbons may be used alone or in admixture of two or more. Of these hydrocarbons, aliphatic hydrocarbons and alicyclic hydrocarbons are preferred.

The lithium-based polymerization initiator is preferably an organic lithium compound. Examples thereof include alkyllithium such as ethyllithium, propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium; phenyllithium, tolyllithium. Allylic lithium such as vinyl lithium and propenyl lithium; alkylene dilithium such as tetramethylene dilithium, pentamethylene dilithium, hexamethylene dilithium and decamethylene dilithium; 1,3-dilithiobenzene, 1, Allylene dilithium such as 4-dilithiobenzene; 1,3,5-trilithiocyclohexane, 1,2,5-trilithionaphthalene, 1,3,5,8-tetralithiodecane, 1,2,3,5 -Tetralithio-4- Hexyl over anthracene, and the like. Of these, n-butyllithium, sec-butyllithium, tert-butyllithium and tetramethylenedilithium are preferable, and n-butyllithium is particularly preferable.
The amount of the organolithium compound used is determined by the polymerization rate in the reaction operation and the molecular weight of the polymer produced, but is usually about 0.02 to 5 mg atoms as lithium atoms per 100 g of the monomer, preferably about 0.005. 05 to 2 mg atoms.

  The polymerization reaction for obtaining the matrix rubber (A) can be performed by either a batch polymerization method or a continuous polymerization method. The polymerization temperature in the polymerization reaction is preferably in the range of 0 to 130 ° C. Further, the polymerization reaction can be carried out by any polymerization method such as isothermal polymerization, temperature rising polymerization or adiabatic polymerization. Furthermore, when performing the polymerization, an allene compound such as 1,2-butadiene may be added in order to prevent the formation of a gel in the reaction vessel.

  The above-mentioned matrix rubber (A) is a polyfunctional modifier, for example, tin tetrachloride, silicon tetrachloride, alkoxysilane having an epoxy group in the molecule (3-glycidoxypropyltriethoxysilane, etc.) or It may have a branched structure by using a modifier such as an amino group-containing alkoxysilane.

The rubber composition of the present invention contains a polar group in the molecule with respect to 100 parts by mass of the matrix rubber (A), and has a polystyrene equivalent weight average molecular weight of 1.0 × 10 ^{3 to} 2.0 × 10 ⁵ . Yes, 1 to 200 parts by mass of the modified hydrogenated polymer (B) composed of an aromatic vinyl-conjugated diene copolymer and / or a conjugated diene polymer in which the hydrogenation rate of the conjugated diene part is 20 to 100%. Cost. If the blending amount is less than 1 part by mass, the effect of increasing tan δ in the high temperature region is not sufficiently exhibited, and if it exceeds 200 parts by mass, the fracture resistance and wear resistance are reduced. A preferable blending amount of the modified hydrogenated polymer (B) is 10 to 100 parts by mass.
The modification including the ionomer modification that introduces the polar group into the polymer molecule enables the modified polymer to form an ion aggregate (cluster) structure, and the cluster composed of the ionic bonds serves as a crosslinking point. The ionic bond is weakened at high temperature and becomes fluid, causing the cluster to collapse at high temperature, which can increase the tan δ in the high temperature region of the rubber composition of the present invention. By using the modified hydrogenated polymer (B) obtained by hydrogenating this modified polymer, the compatibility with the matrix rubber (A) is remarkably improved, whereby the dry road handling stability, fracture resistance and abrasion resistance are improved. It has become possible to greatly improve the performance.
Here, as the polar group, one or more polar groups selected from the group consisting of a carboxylic acid group (—COOH), a sulfonic acid group (—SO ₃ H), a carboxylate functional group, and a sulfonate functional group are used. Of these, carboxylic acid groups are preferable from the viewpoint of easy modification.
The carboxylate functional group refers to a functional group represented by the general formula: —COO · 1 / pM (wherein M is a metal ion or quaternary ammonium ion, and p is the valence of M). . The sulfonate functional group is a functional group represented by the general formula: —SO ₃ .1 / pM (wherein M is a metal ion or quaternary ammonium ion, and p is the valence of M). Say.

The metal ions contained in the carboxylate functional group or the sulfonate functional group are Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Al ^{3. +} , Zn ²⁺ , Cu ²⁺ , Mn ²⁺ , Ni ²⁺ , Co ²⁺ , Co ³⁺ , Fe ³⁺ and Cr ³⁺ are preferably ions selected from one or more types, Quaternary ammonium ions are represented by the general formula (I)
NH _m R ¹ _n ⁺ (I)
(Wherein, m + n = 4, m = 0 to 4, and R ¹ is an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 120 carbon atoms, or an aralkyl group). . Of these, Li ⁺ is particularly preferred because it automatically becomes a Li salt at the end of anionic polymerization.
Examples of the quaternary ammonium ion include ammonium ion (—NH ₄ ⁺ ), trimethylammonium ion, triethylammonium ion, tetramethylammonium ion, tetraethylammonium ion, and triethylmonomethylammonium ion.

  The above-mentioned modified hydrogenated polymer (B) can be obtained by the same production method as that for the matrix rubber (A). That is, the above-mentioned various conjugated diene monomers alone, or the above-mentioned various conjugated diene monomers and the above-mentioned various aromatic vinyl hydrocarbon monomers in the presence of ether or tertiary amine in a hydrocarbon solvent. However, the present invention is not limited to these production methods, and may be produced by a coordination polymerization method. For example, a conjugated diene monomer, particularly a butadiene polymer, can be suitably produced also by coordination polymerization using a neodymium catalyst.

As the polymer modification method, (1) a method of modifying a vinyl bond in a molecular chain, (2) a method of copolymerizing a polar group-containing compound during polymer polymerization, and (3) one or both ends of the molecular chain There is a method of modifying with the above polar group-containing compound. According to the method (3), a carboxylic acid group (—COOH), a sulfonic acid group (—SO ₃ H) is added to one or both ends of the molecular chain of the polymer. It is preferable to introduce at least one polar group selected from the group consisting of a carboxylate functional group and a sulfonate functional group from the viewpoint of increasing tan δ in a high temperature region.
For example, an aromatic vinyl-conjugated diene copolymer and / or a polymer after completion of polymerization of a conjugated diene polymer obtained by using a lithium-based polymerization initiator in the presence of an ether or a tertiary amine in a hydrocarbon solvent By blowing carbon dioxide into the solution, a polymer whose terminal is modified to -COOLi is obtained. Furthermore, the polymer whose terminal is modified with —COOH can be obtained by washing the polymer whose terminal is modified with —COOLi with hydrochloric acid.
In addition, a polymer whose terminal is modified to -SO ₃ Li by blowing sulfur dioxide instead of carbon dioxide, and a polymer whose terminal is modified to -SO ₃ H by washing it with hydrochloric acid are obtained. Can do. A modified polymer in which both ends of the polymer are modified can be obtained by using a dilithium catalyst in the lithium polymerization initiator.

  Furthermore, the modified hydrogenated polymer (B) requires hydrogenation of 20 to 100% of the double bond of the conjugated diene part. There is no restriction | limiting in particular about the hydrogenation method, It can obtain by hydrogenating the said aromatic vinyl-conjugated diene copolymer and / or a conjugated diene polymer according to a conventional method in presence of a hydrogenation catalyst. That is, the modified polymer is a hydrogenation catalyst comprising an organic carboxylate nickel, an organic carboxylate cobalt, a group 1-3 organometallic compound; nickel, platinum, palladium, ruthenium supported on carbon, silica, diatomaceous earth, etc. A modified hydrogenated polymer (B) is obtained by hydrogenating under 1-100 atmospheres of pressurized hydrogen, using a rhodium metal catalyst; one selected from cobalt, nickel, rhodium, ruthenium complex and the like as a catalyst.

  The modified hydrogenated polymer (B) is preferably a styrene-butadiene copolymer or a butadiene polymer. In this case, the amount of bound styrene in the modified hydrogenated polymer (B) is preferably 0 to 60% by mass. This is because if it is 60% by mass or less, the low temperature flexibility becomes better. In the case of a styrene-butadiene copolymer polymer, the amount of bound styrene is preferably 5 to 60% by mass. The amount of vinyl bonds in the butadiene portion of the styrene-butadiene copolymer polymer or the butadiene polymer polymer is not particularly limited. For example, in the anionic polymerization, a range of 10 to 70% is preferably used. In the coordination polymerization, a range of 0.1 to 10% is preferably used.

  The hydrogenation rate of the modified hydrogenated polymer (B) needs to be 20 to 100% of the conjugated diene part, and preferably 40 to 90%. By making the hydrogenation rate of the modified hydrogenated polymer (B) in the above range, the compatibility with the matrix rubber (A) is improved, and the improvement in hysteresis loss due to the crosslinking of the component (B) is reduced little. Can greatly improve the dry road handling stability, fracture resistance and wear resistance.

The modified hydrogenated polymer (B) has a polystyrene-equivalent number average molecular weight of 1.0 × 10 ^{3 to} 2.0 × 10 ⁵ , but it is 1.0 × 10 ^{3 to} 1.0 × 10 ⁵ modified liquid. A polymer is preferable, and a modified liquid polymer having a polystyrene-equivalent number average molecular weight of 1.0 × 10 ³ or more and less than 2.0 × 10 ⁴ is particularly preferable in order to improve dry road handling stability. If the number average molecular weight in terms of polystyrene is less than 2.0 × 10 ⁴ , the amount of ionomer formed is increased, the effect of increasing tan δ in the high temperature region is increased, and the processability of the rubber composition is also improved. 1.0 × 10 ³ or more is preferable because fracture resistance and wear resistance are improved.

  In addition, 40 parts by mass or less of 100 parts by mass of the matrix rubber (A) can be replaced with a rubber component usually used in the tire industry within a range not impairing the object of the present invention. Examples of the rubber component to be replaced include natural rubber and diene synthetic rubber. Examples of the diene synthetic rubber include styrene-butadiene copolymer and polybutadiene, polyisoprene (IR), butyl rubber different from the matrix rubber (A). (IIR), halogenated butyl rubber, ethylene-propylene-diene terpolymer (EPDM), and mixtures thereof. Some of them may have a branched structure by using a polyfunctional modifier, for example, a modifier such as tin tetrachloride.

In the rubber composition of the present invention, in addition to the modified hydrogenated polymer (B), it is necessary to blend a compound (C) containing zinc as an essential component.
The zinc-containing compound is not particularly limited, and examples thereof include zinc oxides, hydroxides, acetates, etc. Among them, zinc oxide that is usually used as a vulcanization accelerating aid in sulfur vulcanizable rubber compositions. (ZnO) is particularly preferred. As a compounding quantity of a zinc oxide, it is necessary to mix | blend 0.1-10 mass parts with respect to 100 mass parts of matrix rubber (A), Preferably it is 0.5-5 mass parts. By setting the blending amount of zinc oxide within the above range, a cluster structure derived from the modified hydrogenated polymer (B) can be easily formed.

Furthermore, in the rubber composition of the present invention, in addition to the modified hydrogenated polymer (B) and the compound containing zinc, Li, Na, Rb, Cs, Mg, Ca, and 100 parts by mass of the matrix rubber (A). It is preferable that 0 to 60 parts by mass of a metal compound and / or an amine compound containing a metal selected from at least one selected from the group consisting of Sr, Ba, Al, Cu, Mn, Ni, Co, Fe and Cr. 1 to 5 parts by mass is more preferable. As described above, zinc white (ZnO) is usually blended as a vulcanization activity aid, and further, a metal compound (D) and / or an amine compound (E) containing a metal other than the above Zn is blended. As a result, these metal compound (D) and / or amine compound (E) reacts with the terminal COOH group of the modified hydrogenated polymer (B), or the terminal COOLi or terminal COOH group reacts with zinc white. Further, the metal exchange reaction proceeds with (COO) ₂ Zn thus produced, and the terminal functional group is changed to improve the physical properties after vulcanization of the rubber composition of the present invention, for example, dry road handling stability.

In the present invention, the metal compound (D) is a metal oxide, metal hydroxide, metal acetate, general formula (II)
R ² SO ₃ · 1 / pM (II)
(Wherein R ² is an alkyl group having 1 to 20 carbon atoms, or an aryl group or aralkyl group having 6 to 120 carbon atoms, M is a metal, and p is a valence of M) and / Or general formula (III)
M (OR ³ ) _p (III)
(Wherein R ³ is an alkyl group having 1 to 20 carbon atoms, or an aryl group or aralkyl group having 6 to 120 carbon atoms, M is a metal, and p is a valence of M). preferable. Among these, magnesium oxide (MgO) or calcium hydroxide [Ca (OH) ₂ ] is particularly preferable.

As the amine compound (E), the general formula (IV)
NH _q R ⁴ _r (IV)
(Wherein q + r = 3, q = 0-3, and R ⁴ is an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 120 carbon atoms, or an aralkyl group). , Triethylamine, diisopropylamine, aniline, benzylamine and the like.

There is no restriction | limiting in particular about the mixing | blending time of the said metal compound (D) and / or an amine compound (E), Although it can mix | blend in any process of a kneading process, a non-pro kneading process, and a pro kneading process, a non-pro process Is particularly preferred.
The non-pro kneading process is a process in which carbon black, oil and other compounding materials are added to the raw rubber and kneaded. The pro kneading process is a vulcanization of the rubber compound obtained in the non-pro kneading process. A process of kneading with an agent, a vulcanization accelerator, and the like.
In the professional kneading step, as described above, a vulcanizing agent, a vulcanization accelerator, and the like are blended, and therefore, the kneading is usually carried out at a low temperature of 110 ° C. or lower in order to prevent the rubber from being burned.

Examples of the filler used in the rubber composition of the present invention include carbon black and / or inorganic filler. There is no restriction | limiting in particular as carbon black, The thing normally used for the rubber industry can be used. For example, FEF, SRF, GPF, HAF, ISAF, SAF, etc. are used. These carbon blacks can be used alone or in combination. Preferably, the nitrogen adsorption specific surface area (N ₂ SA, JIS K 6217-2: 2001) is 60 m ² / g or more and 180 m ² / g or less, and dibutyl phthalate oil absorption (DBP, JIS K 6217-4: 2001A method). There is less of carbon black 180cm ³ / 100g in a 80cm ³ / 100g or more. Although the effect of improving various physical properties is increased by using carbon black, HAF, ISAF, and SAF, which are excellent in wear resistance, are particularly preferable. In this case, the carbon black is preferably used in an amount of 10 to 200 parts by mass, more preferably 20 to 150 parts by mass with respect to 100 parts by mass of the matrix rubber (A). If it is 10 parts by mass or more, it is preferable from the viewpoint of improving fracture resistance, and if it is 200 parts by mass or less, workability is improved, which is preferable. In the case where carbon black is blended alone as the filler, it is particularly preferably used at 30 to 150 parts by mass from the same viewpoint.

Moreover, as an inorganic filler, a silica is preferable. The silica is not particularly limited, but wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), and colloidal silica are preferable. Of these, wet silica is particularly preferred for improving wet road handling stability and low rolling resistance.
Other inorganic fillers include aluminas containing alumina hydrate (Al ₂ O ₃ .H ₂ O), aluminum hydroxide [Al (OH) ₃ ] such as gibbsite and bayerite, aluminum carbonate [Al ₂ (CO _{3) 2],} magnesium hydroxide [Mg (OH) _2], magnesium oxide (MgO), magnesium carbonate (MgCO _3), talc _{(3MgO · 4SiO 2 · H 2} O), attapulgite (5MgO · 8SiO ₂ · 9H ₂ O), titanium white (TiO ₂ ), titanium black (TiO _2n-1 ), calcium oxide (CaO), calcium hydroxide [Ca (OH) ₂ ], aluminum magnesium oxide (MgO · Al ₂ O ₃ ), Clay (Al ₂ O ₃ .2SiO ₂ ), kaolin (Al ₂ O ₃ .2SiO ₂ .2H ₂ O), pyrophyllite (Al ₂ O ₃ .4SiO ₂ .H ₂ O), Ben Tonite (Al ₂ O ₃ .4SiO ₂ .2H ₂ O), aluminum silicate (Al ₂ SiO ₅ , Al ₄ .3SiO ₄ .5H ₂ O, etc.), magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ etc.), Calcium silicate (Ca ₂ · SiO ₄ etc.), aluminum silicate calcium (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), magnesium calcium silicate (CaMgSiO ₄ ), calcium carbonate (CaCO ₃ ), zirconium oxide (ZrO ₂₎ ), Zirconium hydroxide [ZrO (OH) ₂ .nH ₂ O], zirconium carbonate [Zr (CO ₃ ) ₂ ], various zeolites, feldspar, mica, montmorillonite and the like.
Among the above, the case where it is at least one chosen from the oxide or hydroxide of aluminum represented by the following general formula (V), and those hydrates is preferable.
Al ₂ O ₃ · sH ₂ O (V)
[Wherein, s is an integer of 0 to 3. ]

In the rubber composition of the present invention, carbon black or inorganic filler can be used alone or in combination of two or more as reinforcing filler.
For example, the filler can be only silica, and in this case, the silica is preferably used in an amount of 10 to 200 parts by weight, more preferably 30 to 150 parts by weight with respect to 100 parts by weight of the matrix rubber (A). It is done. It is because it is more preferable in terms of fracture resistance and workability within this preferred range.

  As said inorganic filler, it is preferable that the average particle diameter is 10 micrometers or less, and it is more preferable that it is 3 micrometers or less. When the average particle size is 10 μm or less, the fracture resistance and wear resistance of the vulcanized rubber composition can be further improved.

  When the silica is blended in the present invention, it is desirable to further add a silane coupling agent in order to strengthen the bond between the silica and rubber components to further enhance the reinforcing property and improve the wear resistance. .

  Examples of the silane coupling agent used for that purpose include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, Bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxy Silane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N Dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis ( 3-diethoxymethylsilylpropyl) tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, dimethoxymethylsilylpropylbenzothiazole tetrasulfide and the like, and bis (3 -Triethoxysilylpropyl) tetrasulfide, 3-trimethoxysilylpropylbenzothiazoletetras Fido like it is preferable from the viewpoint of improving the reinforcing property effect.

  Said silane coupling agent may be used individually by 1 type, and may use 2 or more types together. As a compounding quantity of a silane coupling agent, 5-20 mass% is preferable with respect to the compounding quantity of the said silica, and 10-15 mass% is more preferable.

  If necessary, the rubber composition of the present invention includes a vulcanizing agent, a vulcanization accelerator, a vulcanization acceleration aid, an anti-aging agent (such as an antioxidant and an ozone deterioration preventing agent), a process oil, and stearic acid. The rubber chemicals usually used in the rubber industry may be appropriately selected according to the purpose and kneaded.

  As the vulcanizing agent, known vulcanizing agents such as sulfur, sulfur donors, organic peroxides, resin vulcanizing agents, metal oxides such as magnesium oxide, and the like are used. Among these, a sulfur-based vulcanizing agent is preferable, and the amount used is preferably 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the matrix component. If the amount is 0.1 parts by mass or more, the vulcanized rubber has improved resistance to breakage, abrasion resistance and low heat build-up, and if it is 10 parts by mass or less, the rubber elasticity function can be more suitably secured. Because.

  Examples of the vulcanization accelerator include known vulcanization accelerators such as thiazoles, sulfenamides, thiurams, guanidines, aldehydes, ammonia, amines, thioureas, dithiocarbamates, and xanthates. Used. Preferably, thiazoles such as M (2-mercaptobenzothiazole), DM (dibenzothiazyl disulfide), CZ (N-cyclohexyl-2-benzothiazylsulfenamide), and guanidines such as DPG (diphenylguanidine) The amount of the vulcanization accelerator is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the matrix component.

  Examples of the anti-aging agent include amines, amine-ketones, imidazoles, phenols, sulfurs, and phosphoruss.

  Examples of the process oil include paraffinic, naphthenic and aromatic oils. Aromatics are used for applications that place importance on tensile strength and wear resistance, and naphthenes or paraffins are used for uses that place importance on hysteresis loss and low-temperature characteristics, and the amount used is based on 100 parts by weight of the matrix component. 1 to 100 parts by mass is preferable. The amount is preferably 100 parts by mass or less from the viewpoint of improving the tensile strength and low heat build-up of the vulcanized rubber composition.

The rubber composition of the present invention is obtained by kneading using a kneader such as a Banbury mixer, a roll, an internal mixer, etc., and after molding and vulcanizing, such as pneumatic tires, various industrial rubber products, etc. Used for applications.
The pneumatic tire of the present invention is manufactured by a usual method. That is, if necessary, the rubber composition of the present invention containing various chemicals as described above is extruded into a tread member at an unvulcanized stage, and pasted and molded by a normal method on a tire molding machine. A green tire is formed. The green tire is heated and pressurized in a vulcanizer to obtain a pneumatic tire.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Various measurements in each example and comparative example were performed as follows.

(1) Weight-average molecular weight and number-average molecular weight in terms of polystyrene (i) 244 type GPC manufactured by Waters Co. is used, and a differential refractometer is used as a detector, and measurement is performed under the following conditions.
Column: Toyo Soda columns GMH-3, GMH-6, G6000H-6
Mobile phase: Tetrahydrofuran (ii) Using a monodisperse styrene polymer manufactured by Waters, a calibration curve was prepared by previously determining the relationship between the molecular weight of the monodisperse styrene polymer peak by GPC and the GPC count. Thus, the weight molecular weight and number average molecular weight of the polymer in terms of polystyrene were determined.
(2) Vinyl bond amount It measured by the infrared method (Morello method).
(3) Bonded styrene content
It was determined by calculating the integral ratio of the spectrum by ¹ H-NMR.
(4) Dry road handling stability From a slab sheet having a thickness of 2 mm obtained by vulcanization at 160 ° C. for 12 minutes, a sheet having a width of 5 mm and a length of 40 mm was cut out and used as a sample. For this sample, tan δ was measured using a spectrometer manufactured by Ueshima Seisakusho Co., Ltd. under the conditions of a distance between chucks of 10 mm, an initial strain of 200 micrometers (microns), a dynamic strain of 1%, a frequency of 52 Hz, and a measurement temperature of 60 ° C. did.
(5) Abrasion resistance Using a Ramborn-type abrasion tester, the amount of abrasion at room temperature was measured, and the reciprocal thereof was expressed as an index with Comparative Example 1 as 100. The higher the value, the better the wear resistance.
(6) Fracture resistance (tensile test)
In accordance with JIS K6251-1993, a tensile test was performed on a vulcanized rubber composition sample obtained by vulcanization at 160 ° C. for 12 minutes, and the tensile stress at break when measured at 23 ° C. (TSb) Asked. The result was expressed as an index with Comparative Example 1 as 100. It shows that it is so favorable that a numerical value is large.

Production Example 1 Production of SBR matrix rubber A-1 To a 5 liter autoclave with a stirring blade sufficiently purged with nitrogen, 3000 g of cyclohexane, 12 g of tetrahydrofuran (THF), 200 g of 1,3-butadiene and 100 g of styrene were introduced, and the temperature in the autoclave. Was adjusted to 21 ° C. Next, 0.10 g of n-butyllithium was added, and polymerization was carried out for 60 minutes under a temperature rising condition, and it was confirmed that the monomer conversion rate was 99%. Thereafter, 3.5 g of 2,6-di-t-butyl-p-cresol was added as an antiaging agent. The obtained SBR matrix rubber A-1 had a polystyrene equivalent weight average molecular weight of 7.0 × 10 ⁵ , a bound styrene content of 33% by mass, and a vinyl bond content of 40%.

Production Example 2 Production of Modified Polymer B-1 Into a 2-liter stainless steel pressure-resistant reaction vessel with a temperature-controlled jacket that was dried and purged with nitrogen, 500 g of cyclohexane, 65 g of 1,3-butadiene and 35 g of styrene were dried in advance. Introduced. The inner temperature was adjusted to 40 ° C. by adjusting the jacket temperature. Next, after introducing 4 mmol of bistetrahydrofurylpropane, a hexane solution of n-butyllithium (18 mmol of n-butyllithium) was added to initiate polymerization, and the temperature was adjusted so that the temperature of the system reached 75 ° C. after 25 minutes. The polymerization reaction was carried out. By adding 120 mmol of carbon dioxide 35 minutes after the start of the polymerization, a —COOLi terminal-modified ionomer-modified liquid SBR was obtained (copolymer B-1). The obtained polymer B-1 had a polystyrene equivalent weight average molecular weight of 15 × 10 ³ , a polystyrene equivalent number average molecular weight of 14 × 10 ³ , a bound styrene amount of 35% by mass, and a vinyl bond amount of 32%.

Production Example 3 Production of Modified Hydrogenated Polymer B-2 Further, the copolymer B-1 was prepared in advance in a separate container with nickel naphthenate: triethylaluminum: 1,3-butadiene = 1: 3: 3 (molar ratio). The catalyst solution was charged so that the amount of nickel was 1 mol with respect to 1000 mol of the butadiene portion of the copolymer. Thereafter, hydrogen was introduced into the reaction system at a hydrogen pressure of 3.04 MPa to obtain an ionomer-modified hydrogenated liquid SBR in which terminal modification and butadiene part were hydrogenated (copolymer B-2). The hydrogenation rate of the butadiene part of the obtained polymer B-2 was 85%. Moreover, the polystyrene conversion weight average molecular weight, polystyrene conversion number average molecular weight, combined styrene amount and vinyl bond amount of the polymer B-2 are the same as those of the polymer B-1.
The hydrogenation rate was calculated from the decrease in the spectrum of the unsaturated bond portion of 100 MHz proton NMR measured at a concentration of 15% by mass using carbon tetrachloride as a solvent.

As the modified polymer B-3, double-terminal carboxylic acid-modified liquid polybutadiene, α, ω-polybutadienedicarboxylic acid manufactured by Nippon Soda Co., Ltd., trade name [C-1000], and number average molecular weight 1200 to 1550 were used (heavy Combined B-3).
Further, as the modified hydrogenated polymer B-4, both-terminal carboxylic acid-modified hydrogenated liquid polybutadiene, a product name [CI-1000] manufactured by Nippon Soda Co., Ltd., a number average molecular weight of about 1400, and a hydrogenation rate of 91% are used. Used (Polymer B-4).

Examples 1-3, Comparative Examples 1 and 2
SBR matrix rubber A-1 prepared in Production Example 1, ionomer-modified liquid SBR and B-1 prepared in Production Example 2, and ionomer-modified hydrogenated liquid SBR and B-2 prepared in Production Example 3 Carboxylic acid-modified liquid polybutadiene, B-3 and both-end carboxylic acid-modified hydrogenated liquid polybutadiene, B-4 were kneaded in a Banbury mixer according to the formulation shown in Table 1, and Examples 1-3 and Comparative Examples 1 and 2 5 types of rubber compositions were obtained. They were vulcanized and measured for dry road handling stability, fracture resistance and wear resistance, respectively. The results are shown in Table 1.

[note]
* 1: SBR matrix rubber A-1 obtained in Production Example 1
* 2: ISAF, Tokai Carbon Co., Ltd., trademark: SEAST 6 (nitrogen adsorption specific surface area: 119m ² / g, DBP oil absorption: 114cm ³ / 100g)
* 3: Triethylamine, manufactured by Tokyo Chemical Industry Co., Ltd. * 4: N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, manufactured by Ouchi Shinsei Chemical Co., Ltd., trademark: NOCRACK 6C
* 5: Diphenylguanidine, manufactured by Ouchi Shinsei Chemical Co., Ltd., Trademark: Noxeller D
* 6: N-tert-butyl-2-benzothiazylsulfenamide, manufactured by Ouchi Shinsei Chemical Co., Ltd., Trademark: Noxeller NS
* 7: Modified liquid SBR (B-1) obtained in Production Example 2
* 8: Modified hydrogenated liquid SBR obtained in Production Example 3 (B-2)
* 9: Both-end carboxylic acid-modified liquid polybutadiene, manufactured by Nippon Soda Co., Ltd., trade name [C-1000] (B-3)
* 10: Carboxylic acid-modified hydrogenated liquid polybutadiene at both ends, trade name [CI-1000] (B-4) manufactured by Nippon Soda Co., Ltd.

As is clear from Table 1, compared with the rubber compositions of Comparative Examples 1 and 2, the rubber compositions (Examples 1 to 3) of the present invention have wear resistance, fracture resistance, and dry road handling stability. Greatly improved.
Further, the five types of rubber compositions of Examples 1 to 3 and Comparative Examples 1 and 2 were disposed on the tread portion of a pneumatic radial tire for passenger cars having a tire size of 205 / 55R16, respectively, and the internal pressure was 230 kPa, the load : Evaluated feelings of test driver when running on a dry circuit course in various driving modes, equivalent to two real cars. The tires provided with the rubber compositions of Examples 1 to 5 were all excellent in dry road handling stability as compared with the tires provided with the rubber compositions of Comparative Examples 1 and 2.

  The rubber composition of the present invention is used for pneumatic tires such as tire treads, under treads, carcass, sidewalls, and bead parts, anti-vibration rubber, belt conveyors, various industrial belts, automobile belts, hoses and other industries. Although it can be used for applications such as products, it is particularly suitably used as a rubber for pneumatic tire treads.

Claims (19)

Aromatic vinyl-conjugated diene copolymer polymerized with a lithium-based polymerization initiator having a polystyrene-reduced weight average molecular weight of 3.0 × 10 ^{5 to} 3.0 × 10 ⁶ obtained by gel permeation chromatography and / or A polar group selected from at least one group selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a carboxylate functional group and a sulfonate functional group with respect to 100 parts by mass of the matrix rubber (A) made of a conjugated diene polymer. Aromatic vinyl-conjugated diene copolymer having a number average molecular weight in terms of polystyrene of 1.0 × 10 ^{3 to} 2.0 × 10 ⁵ and a hydrogenation rate of the conjugated diene part of 20 to 100%. A rubber composition obtained by blending 1 to 200 parts by mass of a modified hydrogenated polymer (B) composed of a polymer and / or a conjugated diene polymer and 0.1 to 10 parts by mass of a compound (C) containing zinc.   The rubber composition according to claim 1, wherein the matrix rubber (A) is a styrene-butadiene copolymer.   The rubber composition according to claim 2, wherein the amount of bound styrene of the matrix rubber (A) styrene-butadiene copolymer is 20 to 40% by mass.   The rubber composition according to claim 2, wherein the vinyl bond content of the butadiene portion of the matrix rubber (A) styrene-butadiene copolymer is 30 to 60%.   The rubber composition according to any one of claims 1 to 4, further comprising 10 to 200 parts by mass of carbon black per 100 parts by mass of the matrix rubber (A).   The rubber composition according to any one of claims 1 to 5, wherein the amount of bound styrene in the modified hydrogenated polymer (B) is 0 to 60% by mass.   The rubber composition according to any one of claims 1 to 6, wherein 10 to 100 parts by mass of the modified hydrogenated polymer (B) is blended with 100 parts by mass of the matrix rubber (A). The rubber composition according to claim 1, wherein the modified hydrogenated polymer (B) has a polystyrene-equivalent number average molecular weight of 1.0 × 10 ³ or more and less than 2.0 × 10 ⁴ .   Polarity wherein the modified hydrogenated polymer (B) is at least one selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a carboxylate functional group and a sulfonate functional group at one or both ends of the molecular chain The rubber composition according to any one of claims 1 to 8, comprising a group.   The rubber composition according to any one of claims 1 to 9, wherein the carboxylate functional group contains a metal ion and / or a quaternary ammonium ion.   The rubber composition according to any one of claims 1 to 10, wherein the sulfonate functional group contains a metal ion and / or a quaternary ammonium ion. Metal ions are Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Al ³⁺ , Zn ²⁺ , Cu ²⁺ , Mn ²⁺ , Ni ^2. The rubber composition according to claim 10 or 11, wherein the rubber composition is an ion selected from at least one selected from the group consisting of ⁺ , Co ²⁺ , Co ³⁺ , Fe ³⁺ and Cr ³⁺ . Quaternary ammonium ions are represented by the general formula (I)
NH _m R ¹ _n ⁺ (I)
11. In the formula, m + n = 4, m = 0 to 4, and R ¹ is an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 120 carbon atoms, or an aralkyl group. Or 11. The rubber composition according to 11.   The rubber composition according to claim 1, wherein the zinc-containing compound (C) is zinc oxide.   Furthermore, a metal compound (D) containing a metal selected from at least one selected from the group consisting of Li, Na, Rb, Cs, Mg, Ca, Sr, Ba, Al, Cu, Mn, Ni, Co, Fe and Cr And / or the rubber composition in any one of Claims 1-14 formed by mix | blending 0-60 mass parts of amine compounds (E). Metal compound (D) is metal oxide, metal hydroxide, metal acetate, general formula (II)
R ² SO ₃ · 1 / pM (II)
(Wherein R ² is an alkyl group having 1 to 20 carbon atoms, or an aryl group or aralkyl group having 6 to 120 carbon atoms, M is a metal, and p is a valence of M) and / Or general formula (III)
M (OR ³ ) _p (III)
(Wherein R ³ is an alkyl group having 1 to 20 carbon atoms, or an aryl group or aralkyl group having 6 to 120 carbon atoms, M is a metal, and p is a valence of M). 15. The rubber composition according to 15. The amine compound (E) has the general formula (IV)
NH _q R ⁴ _r (IV)
(Wherein q + r = 3, q = 0-3, and R ⁴ is an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 120 carbon atoms, or an aralkyl group). The rubber composition as described in 2.   The rubber composition according to any one of claims 15 to 17, wherein the metal compound (D) and / or the amine compound (E) is blended in any one of a kneading step, a non-pro kneading step and a pro kneading step.   A pneumatic tire formed by using the rubber composition according to claim 1 in a tread portion.