JP2020059773A - Tire rubber composition, tread and tire - Google Patents

Abstract

To provide a tire rubber composition, a tread and a tire which are improved in abrasion resistance and fracture characteristics while maintaining grip performance.SOLUTION: There is provided a tire rubber composition which comprises a sulfur oligomer based on 100 pts.mass of a rubber component containing a styrene content of 25 to 50 mass%, a vinyl content of 35 to 50 mass% and a linear styrene-butadiene rubber having a weight average molecular weight of 1000000 to 1400000 and a 5 mass% toluene solution viscosity of 350 mPa s or more.SELECTED DRAWING: None

Description

  The present invention relates to a predetermined rubber composition for tires, a tread constituted by the rubber composition, and a tire provided with the tread.

  The rubber composition used for the tread is required to have excellent abrasion resistance. Abrasion resistance is affected by the glass transition temperature, hardness, filler dispersibility, etc. of the rubber composition. For example, Patent Document 1 discloses a rubber composition for a tire tread that attempts to improve wear resistance and the like by using a component having a low glass transition temperature.

JP, 2004-137463, A

  However, the tire obtained using the rubber composition described in Patent Document 1 has room for improvement in wear resistance.

  The present invention provides a rubber composition for tires that exhibits excellent wear resistance (ablation resistance) and fracture characteristics while maintaining grip performance, a tread produced using the rubber composition for tires, and the tread. It is intended to provide a tire equipped with the tire.

  As a result of intensive studies to solve the above problems, when a sulfur oligomer is used as a vulcanizing agent in a rubber component containing a predetermined linear styrene-butadiene rubber, excellent wear resistance (resistance to abrasion) is maintained while maintaining grip performance. The inventors have found that a rubber composition for a tire exhibiting abradability) and fracture characteristics can be obtained, and further studied to complete the present invention.

That is, the present invention is
[1] Styrene content is 25 to 50% by mass, preferably 30 to 45% by mass, more preferably 35 to 43% by mass, further preferably 37 to 43% by mass, and vinyl content is 35 to 50%, preferably 37 to 45%, more preferably 37 to 43%, weight average molecular weight of 1 million to 1.4 million, preferably 105 to 1.35 million, more preferably 110 to 1.3 million and 5 mass% toluene solution viscosity of 350 mPa · s or more, preferably A rubber composition for tires containing a sulfur oligomer based on 100 parts by mass of a rubber component containing a linear styrene-butadiene rubber having a hardness of 370 to 800 mPa · s, and more preferably 390 to 800 mPa · s.
[2] Content of sulfur oligomer is 0.4 to 10 parts by mass, preferably 0.6 to 8.0 parts by mass, more preferably 1.0 to 6.0 parts by mass, and further preferably 1.0 to 4 parts by mass. 0.0 parts by mass, the rubber composition for a tire according to the above [1],
[3] The rubber composition for a tire according to the above [1] or [2], further containing 21 to 100 parts by mass of liquid styrene-butadiene rubber, preferably 25 to 90 parts by mass, more preferably 30 to 80 parts by mass.
[4] The filler further containing 10 to 180 parts by mass, preferably 30 to 150 parts by mass, more preferably 50 to 120 parts by mass, further preferably 70 to 120 parts by mass, further preferably 90 to 120 parts by mass. 1] to the rubber composition for a tire according to any one of [3],
[5] The rubber composition for tires according to any one of [1] to [4] above, wherein the rubber component is 100% by mass of the linear styrene-butadiene rubber.
[6] A tread produced using the rubber composition for a tire according to any one of [1] to [5] above,
[7] A tire provided with the tread described in [6] above,
Regarding

  According to the present invention, a tire rubber composition showing excellent wear resistance (ablation resistance) and fracture characteristics while maintaining grip performance, a tread composed of the tire rubber composition, and the tread are provided. A tire provided can be provided.

  One embodiment is a linear styrene having a styrene content of 25 to 50% by mass, a vinyl content of 35 to 50%, a weight average molecular weight of 1 to 1.4 million and a 5% by mass toluene solution viscosity of 350 mPa · s or more. It is a rubber composition for tires containing a sulfur oligomer with respect to 100 parts by mass of a rubber component containing butadiene rubber (SBR).

  Another embodiment is a tread produced using the above rubber composition for tires.

  Another embodiment is a tire including the above tread.

  Although not intending to be bound by theory, the following mechanism can be considered as a mechanism for exerting the above effect. That is, by using a linear SBR, since the molecular shape is linear, stress concentration in the molecular chain due to the molecular shape and entanglement of the molecular chains due to the molecular shape can be improved compared to the branched one. The resulting stress concentration is relaxed, while the use of sulfur oligomers relaxes the stress concentration during cross-linking, and the cooperation of these two actions synergistically acts to reduce the stress concentration. It is considered that the reduction is significantly reduced, the fracture characteristics and the wear resistance are significantly improved, and the grip performance is maintained. Further, since the sulfur oligomer has a good affinity with a diene rubber such as SBR, the dispersibility in the diene rubber is good, and this is also considered to contribute to the manifestation of the above effect.

<Rubber component>
The rubber component contains a predetermined linear SBR.

(Straight-chain SBR)
The linear SBR has a styrene content of 25 to 50% by mass, a vinyl content of 35 to 50%, and a weight average molecular weight (Mw) of 1 to 1.4 million.

In the linear SBR, the styrene content may be 25% by mass or more, preferably 30% by mass or more, more preferably 35% by mass or more, and further preferably 37% by mass or more. . The styrene content may be 50 mass% or less, preferably 45 mass% or less, and more preferably 43 mass% or less. If the styrene content is less than 25% by mass, the grip performance tends to deteriorate. On the other hand, when the styrene content exceeds 50% by mass, the initial grip performance tends to deteriorate. The styrene content of SBR is calculated by ¹ H-NMR measurement.

  In the linear SBR, the vinyl content may be 35% or more, preferably 37% or more. The vinyl content may be 50% or less, preferably 45% or less, and more preferably 43% or less. If the vinyl content is less than 35%, the grip performance tends to deteriorate. On the other hand, when the vinyl content exceeds 50%, the initial grip performance tends to deteriorate. The vinyl content (1,2-bond butadiene unit amount) of SBR is measured by an infrared absorption spectrum analysis method.

  The Mw of the linear SBR may be 1 million or more, preferably 1.05 million or more, and more preferably 1.1 million or more. The Mw of the linear SBR may be 1.4 million or less, preferably 1.35 million or less, and more preferably 1.3 million or less. If the Mw is less than 1 million, the abrasion resistance tends to decrease. Further, when Mw exceeds 1.4 million, the rigidity becomes too high, and the grip performance tends to decrease. In addition, Mw is a value calculated as a polystyrene conversion value measured by gel permeation chromatography (GPC), for example.

  The SBR is not particularly limited as long as it is a linear SBR. As an example, SBR is solution polymerization SBR (S-SBR), emulsion polymerization SBR (E-SBR), these modified SBR (modified S-SBR, modified E-SBR), etc. The modified SBR is not particularly limited. As an example, modified SBR includes SBR modified at the terminal or main chain, modified SBR coupled with tin, a silicon compound or the like (condensate, one having a branched structure, etc.), hydrogenated SBR (water. S-SBR, hydrogenated E-SBR) and the like. Among these, SBR is preferably S-SBR. The SBR may be oil-extended.

  The linear SBR has a 5 mass% toluene solution viscosity (Tcp) of 350 mPa · s or more. Here, “5% by mass toluene solution viscosity (Tcp)” is a linear index. From the viewpoint of wear resistance, Tcp is more preferably 370 mPa · s or more, further preferably 390 mPa · s or more. On the other hand, the upper limit of Tcp is not particularly limited. This is because all of them correspond to the linear SBR of this embodiment. However, Tcp is usually 800 mPa · s or less. If it is too high, problems tend to occur in the polymer production process. Note that Tcp was obtained by dissolving 2.28 g of the rubber component in 50 mL of toluene, and then using a standard solution for viscometer calibration (JIS Z8809) as a standard solution, using a Canon Fenske viscometer No. It is defined as the value measured at 25 ° C. using 400.

  The linear SBR can use 1 type (s) or 2 or more types.

  The content of the linear SBR is preferably 70% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more in 100% by mass of the rubber component. The upper limit of the SBR content is not particularly limited. The content of SBR may be 100% by mass in the rubber component. When SBR is included in the above content, the obtained tire is suitable as a high grip tire.

(Other rubber components)
The rubber component in the rubber composition may include a rubber component (other rubber component) other than the linear SBR. Such other rubber component is not particularly limited. As an example, other rubber components include isoprene-based rubbers including natural rubber (NR) and polyisoprene rubber (IR), SBR other than the linear SBR, butadiene rubber (BR), styrene isoprene butadiene rubber (SIBR). ), Chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and other diene rubbers and butyl rubbers other than SBR. These rubber components can use 1 type (s) or 2 or more types. The rubber composition of the present embodiment preferably uses NR and BR as other rubber components. As a result, the tire obtained can maintain and improve fuel economy, wear resistance, durability, wet grip performance, etc. in a well-balanced manner.

<Sulfur oligomer>
The sulfur oligomer is a crosslinkable compound containing sulfur.

  The sulfur oligomer preferably has a polystyrene-equivalent weight average molecular weight (Mw) of 4000 or more as measured by GPC using a chloroform solvent. Since the sulfur oligomer having a Mw of 4000 or more is rubber-like, it has very good affinity and mixing with diene rubbers such as SBR and BR, and the dispersibility in the diene rubber becomes very good. Therefore, wet grip performance and tensile properties tend to be improved. The lower limit of Mw is preferably 8,000 or more, more preferably 10,000 or more. The upper limit of Mw is not particularly limited, and it is difficult to measure the correct molecular weight due to molecular cleavage by a solvent, but the molecular weight is similar to that of SBR or NR, that is, preferably 2,000,000 or less, more preferably 1.6,000,000 or less, and further preferably It is 1.4 million or less. In addition, Mw is Mw in terms of polystyrene when GPC (gel permeation chromatography) measurement is performed using chloroform as a solvent, and is specifically a value measured by the method of Examples described later.

  From the viewpoint of wet grip performance and tensile properties, the sulfur oligomer preferably has a sulfur element content of 10 to 95 mass%. The lower limit is more preferably 30% by mass or more, further preferably 40% by mass or more, and particularly preferably 45% by mass or more. The upper limit is more preferably 90% by mass or less, and further preferably 75% by mass or less.

The sulfur oligomer preferably has a repeating unit represented by the following formula (I).
-R-Sx- (I)
(In the formula, R is a substituted or unsubstituted divalent hydrocarbon group which may contain a hetero atom. X (average value) is 1.0 to 10.0.)

  The substituted or unsubstituted divalent hydrocarbon group which may contain a hetero atom of R may be any of a linear, cyclic or branched group, and a linear group is particularly preferable. The hetero atom is not particularly limited, and examples thereof include oxygen and nitrogen. The carbon number of the divalent hydrocarbon group is preferably 1-20, more preferably 2-18.

  Specific examples of the divalent hydrocarbon group include a substituted or unsubstituted alkylene group having 1 to 18 carbon atoms, a cycloalkylene group having 5 to 18 carbon atoms, and an oxyalkylene group having 1 to 18 carbon atoms. Etc. Of these, a substituted or unsubstituted alkylene group having 1 to 18 carbon atoms and an alkylene group containing a substituted or unsubstituted oxyalkylene group having 1 to 18 carbon atoms are preferable. The substituent of the divalent hydrocarbon group of R is not particularly limited, and examples thereof include functional groups such as a hydroxyl group, a phenyl group and a benzyl group.

  Specific examples of the substituted or unsubstituted alkylene group having 1 to 18 carbon atoms include a substituted or unsubstituted methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, octylene group, nonylene group. , Decylene group, 1,2-propylene group and the like.

Examples of the alkylene group containing a substituted or unsubstituted oxyalkylene group having 1 to 18 carbon atoms include a group represented by (CH ₂ CH ₂ O) p and a group represented by (CH ₂ ) q (p is 1 to 5 An integer, q is an integer of 0 to 2) and an alkylene group including an oxyalkylene group optionally bonded. Preferred _{groups, -CH 2 CH 2 OCH 2 CH} 2 -, - (CH 2 CH 2 O) 2 CH 2 CH 2 -, - (CH 2 CH 2 O) 3 CH 2 CH 2 -, - (CH 2 _{CH 2 O) 4 CH 2 CH} 2 -, - (CH 2 CH 2 O) 5 CH 2 CH 2 -, - (CH 2 CH 2 O) 2 CH 2 - and the like.

  x is 1.0 to 10.0 on average, preferably 2.0 to 6.0, more preferably 3.0 to 5.0, and further preferably 3.5 to 4.5. The number n (average value) of the repeating units represented by the formula (I) is preferably 50 to 1000, more preferably 70 to 500, and further preferably 80 to 300.

  The sulfur oligomer preferably has a polar parameter SP value of 12.5 or less. In this case, the dispersibility in the diene rubber is increased and the performance balance is improved. The upper limit of the SP value is preferably 12.0 or less, more preferably 11.5 or less. The lower limit is not particularly limited, but is preferably 7.0 or more, more preferably 9.0 or more, further preferably 10.0 or more, and particularly preferably 10.5 or more. The polarity parameter SP value means a solubility parameter calculated by the Hoy method based on the structure of the compound. The Hoy method is, for example, K. K. L. Hoy “Table of Solubility Parameters”, Solvent and Coatings Materials Research and Development Department, Union Carbite Corp. (1985).

The sulfur oligomer is preferably obtained by reacting a dihalogen compound represented by the following formula (I-1) with an alkali metal polysulfide represented by the following formula (I-2).
T-R-T (I-1)
(In the formulae, T is the same or different and is a halogen atom. R is a substituted or unsubstituted divalent hydrocarbon group which may contain a hetero atom.)
M ₂ Sx (I-2)
(In the formula, M is an alkali metal. X (average value) is 1.0 to 10.0.)

  In the formula (I-1), examples of the halogen atom of T include fluorine, chlorine, bromine and iodine, and among them, chlorine and bromine are preferable. The substituted or unsubstituted divalent hydrocarbon group which may contain a hetero atom of R is the same as described above.

  In the above formula (I-2), examples of the alkali metal of M include sodium, potassium and lithium. x (average value) is the same as above.

  For example, the sulfur oligomer may be prepared by combining (1) a dihalogen compound of formula (I-1) and an alkali metal polysulfide of formula (I-2) in a non-compatible mixed solvent of a hydrophilic solvent and a hydrophobic solvent. (2) In the solution of the alkali metal polysulfide of formula (I-2), the dihalogen compound of formula (I-1) is added to the alkali metal polysulfide to form an interface. Can be prepared by a method such as a method of adding and reacting at a rate such that a reaction occurs.

  In the production methods (1) and (2), the reaction of the dihalogen compound and the alkali metal polysulfide is an equivalent reaction, and the dihalogen compound: the alkali metal polysulfide is 0.95: 1.0 to It is preferable to react at 1.0: 0.95 (equivalent ratio). The reaction temperature is preferably 50 to 120 ° C, more preferably 70 to 100 ° C.

  The hydrophilic solvent and the hydrophobic solvent (lipophilic solvent) are not particularly limited, and any solvent that is incompatible with the reaction system to form two phases can be used. Examples of the hydrophilic solvent include water; alcohols such as methanol, ethanol, ethylene glycol and diethylene glycol; and the like. Examples of the hydrophobic solvent include aromatic hydrocarbons such as toluene, xylene and benzene; aliphatic hydrocarbons such as pentane and hexane; ethers such as dioxane and dibutyl ether; esters such as ethyl acetate; . The hydrophilic solvent and the hydrophobic solvent may be used alone or in combination of two or more kinds.

  In the case of the above production method (1), it is preferable to use a solvent containing water, ethanol and toluene. In the case of the production method (2), a mixture of an alkali metal polysulfide represented by the formula (I-2) and a solvent containing water and / or ethanol is represented by the formula (I-1). It is preferable to add a mixture of a dihalogen compound and toluene at a suitable rate, and the solvent may be appropriately changed depending on the dihalogen compound.

A catalyst is not particularly required during the reaction of the dihalogen compound and the alkali metal polysulfide, but may be added if necessary. As the catalyst, quaternary ammonium salt, phosphonium salt, crown ether, etc. can be used. ^{_{Specifically, (CH 3) 4 N +}} Cl -, (CH 3) 4 N + Br -, (C 4 H 9) 4 N + Cl -, (C 4 H 9) 4 N + Br -, C ₁₂ H ₂₅ N ⁺ (CH ₃ ) ₃ Br ⁻ , (C ₄ H ₉ ) ₄ P ⁺ Br ⁻ , CH ₃ P ⁺ (C ₆ H ₅ ) ₃ I ⁻ , C ₁₆ H ₃₃ P ⁺ (C ₄ H ₉ ) ₃ Br ^-, include 15-crown-5,18-crown- 6, Benzo-18-crown-6 or the like.

  In addition, (1) a sulfur oligomer having a polystyrene-equivalent weight average molecular weight of 4000 or more by GPC using a chloroform solvent, (2) a sulfur oligomer having a sulfur element content of 10 to 95% by mass, and (3) further the above A sulfur oligomer having a repeating unit represented by the formula (I), (4) and a sulfur oligomer having an SP value of 12.5 or less can also be prepared by the above-mentioned production method.

  The sulfur oligomer can use 1 type (s) or 2 or more types.

  The content of the sulfur oligomer is preferably 0.4 parts by mass or more, more preferably 0.6 parts by mass or more, and further preferably 1 part by mass or more with respect to 100 parts by mass of the diene rubber. The upper limit is not particularly limited, but is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, further preferably 6 parts by mass or less, and further preferably 4 parts by mass or less. Within the above range, good wet grip performance and tensile properties tend to be obtained.

<Other ingredients>
The optional components that are preferably blended in the rubber composition for tires will be described. The rubber composition of the present embodiment may be blended with other components generally used for producing a rubber composition, in addition to the above components. As an example, such optional components are liquid SBR, filler, silane coupling agent, softening agent, stearic acid, zinc oxide, antioxidant, wax, vulcanizing agent, vulcanization accelerator, and the like.

(Liquid SBR)
The liquid SBR preferably has a styrene content of 40 to 60 mass% and an Mw of 4000 to 20000. Further, the content thereof is preferably 21 to 100 parts by mass with respect to 100 parts by mass of the rubber component. By blending the liquid SBR, it is easy to achieve a good balance of grip performance and durability.

  The styrene content of the liquid SBR is preferably 40% by mass or more, and more preferably 45% by mass or more. The styrene content of the liquid SBR is preferably 60% by mass or less, more preferably 55% by mass or less. When the styrene content of the liquid SBR is 40% by mass or more, grip performance tends to be improved. On the other hand, when the styrene content of the liquid SBR is 60% by mass or less, the initial grip performance tends to be improved. The liquid SBR may be a terpolymer composed of a third monomer other than styrene and butadiene.

  The Mw of the liquid SBR is preferably 4000 or more, more preferably 4500 or more. The Mw of the liquid SBR is preferably 20,000 or less, more preferably 15,000 or less. When the Mw of the liquid SBR is 4000 or more, the abrasion resistance tends to be improved. On the other hand, when the Mw of the liquid SBR is 20000 or less, the grip performance tends to be improved. When the Mw is within the above range, the tire obtained is likely to have well balanced wear resistance and grip performance.

  The liquid SBR is preferably a hydrogenated hydrogenated polymer. As a result, the resulting tire is likely to have well balanced wear resistance and grip performance. The hydrogenation rate of the hydrogenated polymer is not particularly limited. As an example, the hydrogenation rate of the hydrogenated polymer is preferably 40% or more, and more preferably 50% or more.

  Liquid SBR can use 1 type (s) or 2 or more types.

  The content of the liquid SBR is preferably 21 parts by mass or more, more preferably 25 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. Further, the content of the liquid SBR is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, and further preferably 80 parts by mass or less with respect to 100 parts by mass of the rubber component. When the content of the liquid SBR is 21 parts by mass or more, grip performance tends to be improved. On the other hand, when the content of the liquid SBR is 100 parts by mass or less, the abrasion resistance tends to be improved.

(filler)
The filler is not particularly limited. The filler can be arbitrarily selected and used from various fillers that have hitherto been widely used in rubber compositions for tires. As an example, the filler is carbon black, silica, calcium carbonate, sericite, aluminum hydroxide, magnesium carbonate, titanium oxide, clay, talc, magnesium oxide, or the like. The filler may be used in combination. Among these, the filler is at least one inorganic filler selected from the group consisting of carbon black, silica, and aluminum hydroxide, from the viewpoint of obtaining excellent grip performance and wear resistance in the resulting tire. It is preferable to contain carbon black or silica, or it is more preferable to contain carbon black and silica. Further, the filler may be made of only carbon black or silica.

  When carbon black is used as the filler, the carbon black is not particularly limited. For example, the carbon black may be general-purpose carbon black or carbon black manufactured by an oil furnace method. Further, carbon blacks having different colloidal characteristics may be used together.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is not particularly limited. As an example, N ₂ SA of carbon black is preferably 100 m ² / g or more, more preferably 105 m ² / g or more, and further preferably 110 m ² / g or more. The N ₂ SA of carbon black is preferably 290 m ² / g or less, more preferably 270 m ² / g or less, and further preferably 250 m ² / g or less. When the N ₂ SA of carbon black is 100 m ² / g or more, the resulting tire tends to show sufficient grip performance. On the other hand, when the N ₂ SA of the carbon black is 600 m ² / g or less, the carbon black is likely to be dispersed in the rubber composition and the wear resistance of the resulting tire is likely to be sufficiently exhibited. The N ₂ SA of carbon black is measured according to JIS K 6217-2: 2001.

  The oil absorption amount (OAN) of carbon black is not particularly limited. As an example, OAN is preferably 50 mL / 100 g or more, and more preferably 100 mL / 100 g or more. Further, OAN is preferably 250 mL / 100 g or less, more preferably 200 mL / 100 g or less, and further preferably 135 mL / 100 g or less. When the OAN is 50 mL / 100 g or more, the resulting tire is likely to show sufficient wear resistance. On the other hand, when the OAN is 250 mL / 100 g or less, the resulting tire tends to show sufficient grip performance. The OAN is measured according to JIS K 6217-4 2008, for example.

  When silica is used as the filler, the silica is not particularly limited. As an example, silica is wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, or the like. Among these, the silica is preferably wet silica. Silica may be used in combination.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is not particularly limited. As an example, N ₂ SA of silica is preferably 80 m ² / g or more, more preferably 100 m ² / g or more, and further preferably 110 m ² / g or more. Further, N ₂ SA of silica is preferably 250 m ² / g or less, more preferably 235 m ² / g or less, further preferably 220 m ² / g or less. When the N ₂ SA of silica is 80 m ² / g or more, the resulting tire is likely to have sufficient durability. Further, when the N ₂ SA of silica is 250 m ² / g or less, the silica is easily dispersed in the rubber composition and the rubber composition is easily processed. The N ₂ SA of silica is measured by the BET method according to ASTM D3037-81.

  As the filler, one kind or two or more kinds can be used. Also, when the filler contains carbon rack or silica, or consists of carbon black or silica only, one kind or two or more kinds of carbon black or silica can be used respectively.

  The content of the filler is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, further preferably 50 parts by mass or more, and 70 parts by mass with respect to 100 parts by mass of the rubber component. More preferably, it is more preferably 90 parts by mass or more. Further, the amount of the filler is preferably 180 parts by mass or less, more preferably 150 parts by mass or less, and further preferably 120 parts by mass or less with respect to 100 parts by mass of the rubber component. By containing the filler in the above blending ratio, the resulting tire is likely to have both excellent grip performance and abrasion resistance.

(Silane coupling agent)
When silica is used as the filler, silica and a silane coupling agent are preferably used in combination. The silane coupling agent is not particularly limited. The silane coupling agent may be any silane coupling agent conventionally used with silica in the rubber industry. As an example, silane coupling agents include sulfide-based silane coupling agents such as bis (3-triethoxysilylpropyl) disulfide and bis (3-triethoxysilylpropyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, Mercapto-based silane coupling agent manufactured and sold by Momentive (a silane coupling agent having a mercapto group), vinyl-based such as vinyltriethoxysilane, amino-based silane coupling agent such as 3-aminopropyltriethoxysilane, Glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane, nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane, and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane And the like. The silane coupling agent may be used in combination.

  When a silane coupling agent is used in combination, the content of the silane coupling agent is preferably 4 parts by mass or more, and more preferably 6 parts by mass or more with respect to 100 parts by mass of silica. Further, the content of the silane coupling agent is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 12 parts by mass or less with respect to 100 parts by mass of silica. . When the content of the silane coupling agent is 4 parts by mass or more, the dispersibility of the filler in the rubber composition may be good. Further, when the content of the silane coupling agent is 20 parts by mass or less, the filler is well dispersed in the rubber composition, and the reinforcing property of the obtained tire is easily improved.

(Softener)
The softener is not particularly limited. The softening agent can be arbitrarily selected and used from various softening agents that have hitherto been widely used in rubber compositions for tires. For example, the softening agent is oil, an adhesive resin, a liquid polymer other than the liquid SBR described above, or the like.

  The oil is not particularly limited. As an example, the oil is mineral oil such as naphthene oil, aroma oil, process oil, paraffin oil and the like. The oil may be used in combination.

  When oil is contained, the content of oil is not particularly limited. As an example, the content of oil is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, based on 100 parts by mass of the rubber component. Further, the content of oil is preferably 50 parts by mass or less, and more preferably 45 parts by mass or less with respect to 100 parts by mass of the rubber component. When the oil content is within the above range, the resulting tire has excellent wear resistance. The oil content also includes the amount of oil used in oil extension.

  The adhesive resin is not particularly limited. As an example, the pressure-sensitive adhesive resin is an aromatic petroleum resin or the like which has heretofore been widely used in rubber compositions for tires. The type of aromatic petroleum resin is not particularly limited. As an example, the aromatic petroleum resin is a phenol resin, coumarone indene resin, terpene resin, styrene resin, acrylic resin, rosin resin, dicyclopentadiene resin (DCPD resin) and the like. Aromatic petroleum resins may be used in combination.

  Examples of the phenolic resin include those manufactured and sold by BASF, Taoka Chemical Co., Ltd., and the like. Examples of the coumarone indene resin include those manufactured and sold by Nikki Chemical Co., Ltd., Nippon Steel Chemical Co., Ltd., Shin Nippon Petrochemical Co., Ltd., and the like. Examples of the styrene resin include those manufactured and sold by Arizona Chemical Company. Examples of the terpene resin include those manufactured and sold by Arizona Chemical Co., Ltd., Yasuhara Chemical Co., Ltd., and the like. Among these, the aromatic petroleum resin preferably contains a phenolic resin, a coumarone indene resin, a terpene resin, and an acrylic resin from the viewpoint that the tire obtained has more excellent grip performance during running.

  The Mw of the aromatic petroleum resin is preferably 1500 or more, more preferably 2000 or more. The Mw of the aromatic petroleum resin is preferably 5000 or less, more preferably 4500 or less. When the Mw of the aromatic petroleum resin is 1500 or more, the obtained tire tends to have high grip performance. On the other hand, when the Mw of the aromatic petroleum resin is 5000 or less, the obtained tire tends to have high grip performance.

  The content of the aromatic petroleum resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, further preferably 15 parts by mass or more, and further preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. preferable. Further, the content of the aromatic petroleum resin is preferably 50 parts by mass or less, and more preferably 45 parts by mass or less with respect to 100 parts by mass of the rubber component. When the content of the aromatic petroleum resin is 5 parts by mass or more, the obtained tire is likely to have improved grip performance during running. On the other hand, when the content of the aromatic petroleum resin is 100 parts by mass or less, the resulting tire is likely to show sufficient wear resistance.

  The softening point of the aromatic petroleum resin is not particularly limited. As an example, the softening point is preferably 60 ° C. or higher, and more preferably 80 ° C. or higher. The softening point is preferably 170 ° C or lower, more preferably 160 ° C or lower. When the softening point is 60 ° C. or higher, the obtained tire is likely to show excellent grip performance during running. Further, when the softening point is 170 ° C. or lower, the obtained tire is likely to show excellent initial grip performance. The softening point can be defined as the temperature at which the sphere is lowered by measuring the softening point defined by JIS K 6220-1: 2001 with a ring and ball softening point measuring device.

  Liquid polymers other than the liquid SBR described above (other liquid polymers) are not particularly limited. As an example, the other liquid polymer is a liquid styrene isoprene polymer. Other liquid polymers may be used in combination.

  When the other liquid polymer is contained, the content of the other liquid polymer is not particularly limited. As an example, the content of the other liquid polymer is preferably 5 parts by mass or more, and more preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. Further, the content of the liquid polymer is preferably 50 parts by mass or less, and more preferably 45 parts by mass or less with respect to 100 parts by mass of the rubber component. When the content of the other liquid polymer is within the above range, the resulting tire has excellent wear resistance.

(Anti-aging agent)
The antiaging agent is not particularly limited. The antioxidant can be arbitrarily selected and used from various antioxidants that have been generally used in rubber compositions for tires. For example, the antiaging agent is a quinoline antiaging agent, a quinone antiaging agent, a phenol antiaging agent, a phenylenediamine antiaging agent, or the like. Anti-aging agents may be used in combination.

  When the antioxidant is contained, the content of the antioxidant is not particularly limited. As an example, the content of the antioxidant is preferably 0.5 parts by mass or more, and more preferably 0.8 parts by mass or more with respect to 100 parts by mass of the rubber component. Further, the content of the antioxidant is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and further preferably 3 parts by mass or less, relative to 100 parts by mass of the rubber component. When the content of the antioxidant is within the above range, the filler is easily dispersed well. Further, the obtained rubber composition is easily kneaded.

(Vulcanizing agent)
In addition to the above-mentioned sulfur oligomer, a vulcanizing agent (additional vulcanizing agent) can be used. In this case, the additional vulcanizing agent is in an amount that does not negate the effect of the sulfur oligomer. The amount of such an additional vulcanizing agent can be appropriately set by those skilled in the art according to the type thereof. The additional vulcanizing agent is a vulcanizing agent commonly used in the rubber industry, and one example thereof is a sulfur-containing compound such as sulfur or caprolactam disulfide. Sulfur as an additional vulcanizing agent is powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, oil-treated sulfur and the like. The additional vulcanizing agent may be used in combination.

(Vulcanization accelerator)
The vulcanization accelerator is not particularly limited. For example, the vulcanization accelerator includes a guanidine vulcanization accelerator, an aldehyde-amine vulcanization accelerator, an aldehyde-ammonia vulcanization accelerator, a thiazolyl vulcanization accelerator, and a sulfenamide vulcanization accelerator. Agents, thiourea vulcanization accelerators, thiuram vulcanization accelerators, dithiocarbamate vulcanization accelerators, zandate vulcanization accelerators and the like. Among these, thiazolyl vulcanization accelerators and thiuram vulcanization accelerators are preferable. The vulcanization accelerator may be used in combination.

  As the thiazolyl vulcanization accelerator, a vulcanization accelerator having a benzothiazolyl sulfide group is particularly preferable. The vulcanization accelerator having a benzothiazolyl sulfide group is not particularly limited, and examples thereof include N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS) and N-cyclohexyl-2-benzothiazolyl. Rusulfenamide (CBS), N, N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), N, N-diisopropyl-2-benzothiazolesulfenamide, N, N-di (2-ethylhexyl)- 2-benzothiazolylsulfenamide (BEHZ), N, N-di (2-methylhexyl) -2-benzothiazolylsulfenamide (BMHZ), N-ethyl-Nt-butylbenzothiazole-2- Sulfenamide-based vulcanization accelerators such as sulfenamide (ETZ), N-tert-butyl-2-benzo Azolyl sulfenimide (TBSI), a di-2-benzothiazolyl disulfide (DM) and the like. Of these, DM is preferable. The thiazolyl vulcanization accelerator may be used in combination.

  Examples of thiuram-based vulcanization accelerators include tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N), among which TOT- N is preferred. A thiuram vulcanization accelerator may be used in combination.

  The content of the vulcanization accelerator is not particularly limited. As an example, the content of the vulcanization accelerator is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more with respect to 100 parts by mass of the rubber component. Further, the content of the vulcanization accelerator is preferably 10 parts by mass or less, and more preferably 9 parts by mass or less with respect to 100 parts by mass of the rubber component. When the content of the vulcanization accelerator is 0.5 parts by mass or more, the rubber composition can easily obtain a sufficient vulcanization rate during vulcanization. Further, when the content of the vulcanization accelerator is 10 parts by mass or less, blooming is less likely to occur in the obtained tire.

<Manufacturing method>
The rubber composition for tires, the tire member (for example, tread), and the tire can be manufactured by a general method.

  To give an example, a rubber composition for a tire is a vulcanizing agent and a vulcanizing agent among the above-mentioned components using a known kneading machine generally used in the rubber industry, such as a Banbury mixer, a kneader, and an open roll. An unvulcanized rubber composition for tires can be produced by kneading components other than the accelerator, adding a vulcanizing agent and a vulcanization accelerator thereto, and further kneading.

  The rubber composition for a tire in the unvulcanized stage thus obtained is extruded in accordance with the shape of the desired tire member (for example, the shape of the tread portion) to obtain the desired tire member in the unvulcanized stage (for example, , Tread) can be manufactured.

  The desired tire member in the unvulcanized stage thus obtained is laminated together with other tire members on a tire molding machine, and then molded by a general-purpose method to prepare an unvulcanized tire member having the desired tire member. A vulcanized tire can be manufactured.

  By heating and pressing the unvulcanized tire thus obtained in a vulcanizer, a tire having a desired tire member can be manufactured.

  The tire of this embodiment may be a pneumatic tire or a non-pneumatic tire, but is preferably a pneumatic tire. Further, as the pneumatic tire, it can be used for various tires such as tires for passenger cars, tires for trucks and buses, tires for two-wheeled vehicles, tires for competition, run flat tires, etc. Since both are excellent in grip performance, they can be suitably used as a high performance tire.

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

<Various chemicals used in Examples and Comparative Examples>
SBR1: Linear SBR prepared by the method for producing SBR1 described below (oil extended (oil content 37.5 parts by mass relative to rubber solid content 100 parts by mass), styrene content: 40% by mass, vinyl content: 40%, Mw: 1.2 million, 5 mass% toluene solution viscosity: 390 mPa · s)
SBR2: branched SBR prepared by the method for producing SBR2 described later (oil extended (oil content is 37.5 parts by mass relative to 100 parts by mass of rubber solid content), styrene content: 40 mass%, vinyl content: 40) %, Mw: 1.2 million, 5 mass% toluene solution viscosity: 340 mPa · s)
Filler: Seast 9H (N ₂ SA: 142 m ² / g, available from Tokai Carbon Co., Ltd.)
Liquid SBR: RICON100 (liquid SBR, amount of styrene: 25% by mass, Mw: 4500, available from Cray valley)
Resin: coumarone V120 (coumarone indene resin, softening point: 120 ° C, available from Nikki Chemical Co., Ltd.)
Anti-aging agent: Nocrac 6C (N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, available from Ouchi Shinko Chemical Industry Co., Ltd.)
Wax: Ozoace 0355 (available from Nippon Seiro Co., Ltd.)
Stearic acid: Paulownia (available from NOF CORPORATION)
Zinc oxide: 2 types of zinc oxide (available from Mitsui Mining & Smelting Co., Ltd.)
Sulfur: Sulfur powder (available from Karuizawa Smelter Co., Ltd.)
Sulfur oligomer 1: Sulfur oligomer prepared by the production method of sulfur oligomer 1 described later Sulfur oligomer 2: Sulfur oligomer prepared by the production method of sulfur oligomer 2 described below Sulfur oligomer 3: Sulfur prepared by the production method of sulfur oligomer 3 described below Oligomer vulcanization accelerator 1 (accelerator DM): Nocceller DM (di-2-benzothiazolyl disulfide, available from Ouchi Shinko Chemical Industry Co., Ltd.)
Vulcanization accelerator 2 (accelerator TOT): Nocceller TOT-N (tetrakis (2-ethylhexyl) thiuram disulfide, available from Ouchi Shinko Chemical Industry Co., Ltd.)

The various chemicals used in the method for producing SBR1 and SBR2 are shown below.
Hexane: Kanto Chemical Co., Ltd. 1.6 M n-butyllithium hexane solution: Kanto Chemical Co., Ltd. isopropanol: Kanto Chemical Co., Ltd. Styrene: Kanto Chemical Co., Ltd. Butadiene: Takachiho Chemical Co., Ltd. Tetramethylethylenediamine: N, N, N ', N'-tetramethylethylenediamine (TMEDA), tetrachlorosilane manufactured by Kanto Chemical Co., Inc.

<Method of manufacturing SBR1>
1000 g of hexane, 60 g of butadiene, 40 g of styrene, and 20 mmol of TMEDA were placed in a 3 L pressure-resistant stainless steel container that had been sufficiently replaced with nitrogen. Next, a small amount of n-butyllithium / hexane solution was added to the polymerization vessel as a scavenger in order to detoxify impurities that act to deactivate the polymerization initiator in advance. Further, an n-butyllithium / hexane solution (0.083 mmol as the content of n-butyllithium) was added, and a polymerization reaction was carried out at 50 ° C. for 3 hours. Then, 1500 mL of a 1 M isopropanol / hexane solution was added dropwise to terminate the reaction. Next, the polymerization liquid was evaporated at room temperature for 24 hours, and further dried under reduced pressure at 80 ° C. for 24 hours to obtain SBR1.

<Method of manufacturing SBR2>
1000 g of hexane, 60 g of butadiene, 40 g of styrene, and 20 mmol of TMEDA were placed in a 3 L pressure-resistant stainless steel container that had been sufficiently replaced with nitrogen. Next, a small amount of n-butyllithium / hexane solution was added to the polymerization vessel as a scavenger in order to detoxify impurities that act to deactivate the polymerization initiator in advance. Furthermore, an n-butyllithium / hexane solution (0.332 mmol as the content of n-butyllithium) was added, and a polymerization reaction was carried out at 50 ° C. for 3 hours. 0.083 mmol of tetrachlorosilane was added. Then, 1500 mL of a 1 M isopropanol / hexane solution was added dropwise to terminate the reaction. Next, the polymerization liquid was evaporated at room temperature for 24 hours, and further dried under reduced pressure at 80 ° C. for 24 hours to obtain SBR2.

<Method for producing sulfur oligomer 1 (rubber-like)>
In a flask completely replaced with an inert gas such as nitrogen gas or argon gas, 104.4 g (0.180 mol) of a 30% aqueous solution of sodium polysulfide, 150 g of ion-exchanged water and 150 g of ethanol were taken and stirred, and the temperature was raised to 90 ° C. , 25.0 g (0.175 mol) of bis (2-chloroethyl) ether diluted with 100 g of toluene was added dropwise over 2 hours, and the mixture was reacted at the same temperature for 3 hours to separate the organic layer, and then at 90 ° C. Concentration and drying in vacuum gave 27.3 g of the desired oligomer. The obtained sulfur oligomer 1 (rubber-like) had Mw of 21 million, a content of elemental sulfur of 55% by mass, repeating units (R = (CH ₂ ) ₂ O (CH ₂ ) ₂ , x (average) of the above formula (I). Value) = 4.0, SP value 11.1).

<Method for producing sulfur oligomer 2 (liquid)>
In a flask completely replaced with an inert gas such as nitrogen gas or argon gas, 104.4 g (0.180 mol) of 30% sodium polysulfide aqueous solution, 150 g of ion-exchanged water, and tetrabutylammonium chloride (TBAB) 1 as a reaction catalyst were added. After taking 0.25 g and stirring and heating to 90 ° C., 25.0 g (0.175 mol) of bis (2-chloroethyl) ether diluted with 100 g of toluene was added dropwise over 2 hours, and further reacted at the same temperature for 3 hours. After separating the organic layer by vacuum concentration and drying at 90 ° C., 25.5 g of the target oligomer was obtained. The obtained sulfur oligomer 2 (liquid) had Mw 2670, a content of elemental sulfur of 55% by mass, a repeating unit (R = (CH ₂ ) ₂ O (CH ₂ ) ₂ , x (average value) of the above formula (I). = 4.0, SP value 11.1).

<Method for producing sulfur oligomer 3 (liquid)>
A flask completely replaced with an inert gas such as nitrogen gas or argon gas was charged with 104.4 g (0.180 mol) of 30% sodium polysulfide aqueous solution and 150 g of ion-exchanged water, stirred and heated to 90 ° C., and then 100 g of toluene. 25.0 g (0.175 mol) of bis (2-chloroethyl) ether diluted with was added dropwise over 2 hours, further reacted at the same temperature for 3 hours to separate the organic layer, and then concentrated under vacuum at 90 ° C. After drying, 25.0 g of the target oligomer was obtained. The obtained sulfur oligomer 3 (liquid) had Mw 1250, a content of elemental sulfur of 55% by mass, repeating units of the above formula (I) (R = (CH ₂ ) ₂ O (CH ₂ ) ₂ , x (average value)). = 4.0, SP value 11.1).

The structure of the sulfur oligomer 1 used in the examples is presumed to be a linear oligomer having a repeating unit represented by the following formula.

The structure of the sulfur oligomers 2 to 3 is presumed to be a mixture of the above linear oligomer and a cyclic oligomer represented by the following formula (a mixture of a linear oligomer and / or a cyclic oligomer).

<Mw of sulfur oligomer>
Mw was calculated by standard polystyrene conversion based on the measurement value measured by gel permeation chromatograph (GPC) with the following pretreatment method, apparatus and measurement conditions.
(1) Pretreatment method The sample was dissolved in a solvent and filtered with a 0.45 μm membrane filter to obtain a measurement solution.
(2) Device / Measurement conditions Device: Tosoh Corp. GPC-8000 series column: Tosoh Corp. TSKGel (registered trademark) SuperAWM-H × 2 + SuperAW2
500 x 1 (6.0 mm ID x 150 mm x 3)
Solvent: Chloroform Flow rate: 0.6 mL / min.
Detector: RI detector Column temperature: 40 ° C
Injection volume: 20 μL
Molecular weight standard: Standard polystyrene

Examples 1-5 and Comparative Examples 1-3
<Unvulcanized rubber composition>
According to the formulation shown in Table 1 below, using a 1.7 L closed Banbury mixer, the vulcanizing agent and chemicals other than the vulcanization accelerator were kneaded for 5 minutes until the discharge temperature reached 160 ° C., and kneaded. I got a thing. Next, using a biaxial open roll, a vulcanizing agent and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded for 4 minutes to 105 ° C. to obtain an unvulcanized rubber composition.

<Vulcanized rubber composition>
The unvulcanized rubber composition obtained above was press-vulcanized at 170 ° C. for 15 minutes to obtain a vulcanized rubber composition (sheet).

<Test tire>
The unvulcanized rubber composition obtained above is extrusion-molded into the shape of a tire tread with an extruder equipped with a die having a predetermined shape, and bonded with other tire members to form an unvulcanized tire at 170 ° C. A test tire (size: 195 / 65R15) was produced by press vulcanizing for 12 minutes under the conditions.

<Evaluation>
With respect to the obtained test tire and vulcanized rubber composition, wear resistance (ablation resistance), fracture characteristics and grip performance were evaluated according to the following evaluation methods. The results are shown in Table 1.

(Abrasion resistance)
Each test tire was mounted on all wheels of a domestic FR vehicle with a displacement of 2000 cc, and the groove depth of the tire tread portion after a mileage of 8000 km was measured to determine the mileage when the tire groove depth decreased by 1 mm. The results are shown as an index with 100 as the running distance when the tire groove of the reference comparative example is reduced by 1 mm. The larger the index, the better the wear resistance.

(Fracture characteristics)
For each vulcanized rubber composition, tensile strength and elongation at break were measured according to JIS K 6251 "Vulcanized rubber and thermoplastic rubber-Determination of tensile properties". Furthermore, the breaking energy was calculated by the formula: tensile strength × elongation at break / 2. The results are shown as an index by the following calculation formula, with the breaking energy index of each reference comparative example being 100. The larger the breaking energy index, the better the breaking characteristics.
(Fracture energy index) =
(Fracture energy of each formulation) / (Fracture energy of each reference comparative example) × 100

(Grip performance)
Each test tire was mounted on all wheels of a domestic FR vehicle with a displacement of 2000 cc, and the vehicle was run for 10 laps on a test course on a dry asphalt surface. The test driver evaluated the stability of the control at that time, and indicated as an index with the standard comparative example as 100. The larger the index, the higher the grip performance.

  As shown in Table 1, the rubber composition and the tire of the example are compared with the comparative example (that is, the comparison between the example 1 and the comparative examples 1 to 3) and the abrasion resistance while maintaining the grip performance. The fracture characteristics are synergistically improved.

Claims (7)

A rubber component containing a linear styrene-butadiene rubber having a styrene content of 25 to 50% by mass, a vinyl content of 35 to 50%, a weight average molecular weight of 1 to 1.4 million and a 5% by mass toluene solution viscosity of 350 mPa · s or more. A rubber composition for tires containing a sulfur oligomer with respect to 100 parts by mass. The rubber composition for a tire according to claim 1, wherein the content of the sulfur oligomer is 0.4 to 10 parts by mass. The tire rubber composition according to claim 1 or 2, further comprising 21 to 100 parts by mass of liquid styrene-butadiene rubber. The rubber composition for a tire according to claim 1, further comprising 10 to 180 parts by mass of a filler. The rubber composition for tires according to any one of claims 1 to 4, wherein a rubber component comprises 100% by mass of the linear styrene-butadiene rubber. A tread produced using the rubber composition for a tire according to claim 1. A tire provided with the tread according to claim 6.