JP2020094112A - Rubber composition and tire - Google Patents

Abstract

To provide a rubber composition having highly balanced WET performance, low-loss properties and steering stability.SOLUTION: The rubber composition contains a diene rubber component, a styrene-alkylene block copolymer, a polyolefin-based softener, and a reinforcing filler. The total styrene content of the styrene-alkylene block copolymer is 30 mass% or more based on the total mass of the styrene-alkylene block copolymer. The polyolefin-based softener contains one or more selected from the group consisting of alkene polymers and hydrogenated diene polymers. The reinforcing filler is contained in an amount of 45 pts.mass or more per 100 pts.mass of the diene rubber component.SELECTED DRAWING: None

Description

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

In recent years, the demand for low fuel consumption of automobiles has been increasing in connection with the movement of global carbon dioxide emission regulations accompanying the increasing interest in environmental problems. In order to meet such demands, reduction in rolling resistance is also required for tire performance. Conventionally, a method of optimizing a tire structure has been studied as a method of reducing rolling resistance of a tire, but a rubber composition applied to a tire has a low tan δ (hereinafter, referred to as “low loss property”) and a low value. The use of a material having an excellent heat generation property is also currently practiced as a general method.

Further, conventionally, tires having both WET performance and low loss have been mainly used by making full use of styrene-butadiene rubber and silica.

International Publication No. 2015/079703

In recent years, it has been found that a higher WET performance can be exhibited by blending a thermoplastic resin and a softening agent in a larger amount than in the past based on natural rubber (see, for example, Patent Document 1). However, in that case, there was room for improvement in low loss and steering stability.

Therefore, an object of the present invention is to provide a rubber composition in which the WET performance, the low loss property, and the steering stability are highly balanced. Another object of the present invention is to provide a tire in which the WET performance, the low loss property, and the steering stability are highly balanced.

The rubber composition according to the present invention contains a diene rubber component, a styrene/alkylene block copolymer, a polyolefin softening agent, and a reinforcing filler, and the total styrene content of the styrene/alkylene block copolymer. Is 30% by mass or more based on the total mass of the styrene/alkylene block copolymer, and the polyolefin-based softening agent is one or more selected from the group consisting of alkene polymers and hydrogenated diene polymers. And a rubber composition containing 45 parts by mass or more of the reinforcing filler per 100 parts by mass of the diene rubber component.
Thereby, the WET performance, the low loss property, and the steering stability can be highly balanced.

The rubber composition according to the present invention, alkylene blocks of the styrene-alkylene block _{copolymer, - (CH 2 -CH (C} 2 H 5)) - units and _{(A) - (CH 2 -CH} 2) - It is preferable that the total content of the unit (A) and the unit (B) is 40% by mass or more based on the total mass of the unit (A) and the unit (B).
As a result, it is possible to achieve both the WET performance and the low loss property while having excellent steering stability.

The rubber composition according to the present invention preferably contains 5 to 25 parts by mass of the polyolefin softener per 100 parts by mass of the diene rubber component.
As a result, the WET performance, the low loss property, and the steering stability can be more highly balanced.

In the rubber composition according to the present invention, the diene rubber component preferably contains 40 parts by mass or more of natural rubber per 100 parts by mass of the diene rubber component.
Thereby, cold resistance can be improved.

The rubber composition according to the present invention preferably contains 1 to 70 parts by mass of a thermoplastic resin per 100 parts by mass of the diene rubber component.
Thereby, the WET performance can be further improved.

In the rubber composition according to the present invention, the reinforcing filler preferably contains silica and a white filler other than silica.
Thereby, the WET performance can be further improved.

The rubber composition according to the present invention is preferably for tires.
As a result, the WET performance of the tire, the low loss property, and the steering stability can be highly balanced.

The rubber composition according to the present invention is more preferably used for tire treads.

The tire according to the present invention is a tire using any one of the rubber compositions described above.
As a result, the WET performance of the tire, the low loss property, and the steering stability can be highly balanced.

According to the present invention, it is possible to provide a rubber composition in which the WET performance, the low loss property, and the steering stability are highly balanced. According to the present invention, it is possible to provide a tire in which the WET performance, the low loss property, and the steering stability are highly balanced.

Hereinafter, embodiments of the present invention will be described. These descriptions are for the purpose of illustrating the present invention and are not intended to limit the present invention in any way.

(Rubber composition)
The rubber composition according to the present invention contains a diene rubber component, a styrene/alkylene block copolymer, a polyolefin softening agent, and a reinforcing filler, and the total styrene content of the styrene/alkylene block copolymer. Is 30% by mass or more based on the total mass of the styrene/alkylene block copolymer, and the polyolefin-based softening agent is one or more selected from the group consisting of alkene polymers and hydrogenated diene polymers. And a rubber composition containing 45 parts by mass or more of the reinforcing filler per 100 parts by mass of the diene rubber component.
Thereby, the WET performance, the low loss property, and the steering stability can be highly balanced.

<Diene rubber component>
As the diene rubber component, the diene rubber component used in known rubber compositions can be used. Examples of the diene rubber component include natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), acrylonitrile butadiene rubber, chloroprene rubber, synthetic polyisoprene rubber, and modified products thereof. The diene rubber components may be used alone or in combination of two or more.

The rubber composition according to the present invention preferably contains natural rubber as the diene rubber component.
Thereby, cold resistance can be improved.

In the rubber composition according to the present invention, the diene rubber component preferably contains 40 parts by mass or more of natural rubber per 100 parts by mass of the diene rubber component.
Thereby, cold resistance can be improved.

The rubber composition according to the present invention preferably contains, as the diene rubber component, at least one selected from the group consisting of unmodified SBR and modified SBR.

The rubber composition according to the present invention preferably contains a modified conjugated diene polymer such as modified SBR as a diene rubber component.

As the modified conjugated diene-based polymer, for example, the weight average molecular weight described in International Publication No. 2016/133154 is 20×10 ⁴ or more and 300×10 ⁴ or less, based on the total amount of the modified conjugated diene-based polymer. The modified conjugated diene polymer having a molecular weight of 200×10 ⁴ or more and 500×10 ⁴ or less is contained in an amount of 0.25% by mass or more and 30% by mass or less, and the contraction factor (g′) is less than 0.64. Examples include modified conjugated diene-based polymers.

The diene rubber component of the present invention may be a modified SBR other than those described in WO 2016/133154 or an unmodified SBR. For example, other modified SBRs include modified (co)polymers as the polymer component P2 in WO 2017/0777712 and modified polymers C and D described in Examples.

The rubber composition according to the present invention may include a diene rubber component, and may or may not include a non-diene rubber component in addition to the diene rubber component.

Examples of the non-diene rubber component include butyl rubber (IIR), ethylene/propylene rubber (EPM), ethylene/propylene/diene rubber (EPDM), urethane rubber, silicone rubber, and fluororubber. Since EPDM has a very small amount of diene, it is used as a non-diene rubber component. The non-diene rubber component may be used alone or in combination of two or more.

When the non-diene rubber component is included, the proportion of the diene rubber component in the entire rubber component may be, for example, 70% by mass or more and less than 100% by mass.

<Styrene/alkylene block copolymer>
The styrene/alkylene block copolymer is a copolymer having a block derived from a styrene-based monomer and an alkylene block. The styrene/alkylene block copolymer in the rubber composition according to the present invention has a total styrene content of the styrene/alkylene block copolymer of 30% by mass or more based on the total mass of the styrene/alkylene block copolymer. is there. When the total styrene content is 30% by mass or more, steering stability is enhanced. The styrene/alkylene block copolymer may be used alone or in combination of two or more.

The total styrene content of the styrene/alkylene block copolymer (total content of blocks derived from styrene-based monomers) may be appropriately adjusted in the range of 30% by mass or more, and is, for example, 30 to 60% by mass.

The rubber composition according to the present invention preferably has the total styrene content of 50% by mass or more. Thereby, steering stability can be further enhanced.

In the present invention, the styrene content of the styrene/alkylene block copolymer and the content of alkylene units described later are determined by the ¹ H-NMR integral ratio.

The styrene block of the styrene/alkylene block copolymer has units derived from a styrene monomer (polymerized styrene monomer). Examples of such a styrene-based monomer include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene and the like. Among these, styrene is preferable as the styrene-based monomer.

The alkylene block of the styrene/alkylene block copolymer has an alkylene (divalent saturated hydrocarbon group) unit. Examples of such an alkylene unit include an alkylene group having 1 to 20 carbon atoms. The alkylene unit may have a linear structure, a branched structure, or a combination thereof. The alkylene units of the linear structure, for example, - (CH ₂ -CH ₂₎ - units (ethylene units), - like units (butylene _{units) - (CH 2 -CH 2 -CH} 2 -CH 2) .. The alkylene units of the branched structure, for _{example, - (CH 2 -CH (C} 2 H 5)) - units (butylene units), and the like. Of these, the alkylene _{units, - (CH 2 -CH (C} 2 H 5)) - preferably has a unit.

The total content of alkylene units may be appropriately adjusted, but is, for example, 40 to 70 mass% with respect to the total mass of the styrene/alkylene block copolymer.

The rubber composition according to the present invention, alkylene blocks of the styrene-alkylene block _{copolymer, - (CH 2 -CH (C} 2 H 5)) - units and _{(A) - (CH 2 -CH} 2) - It is preferable that the total content of the units (B) is 40% by mass or more based on the total mass of all the alkylene blocks. As a result, it is possible to achieve both the WET performance and the low loss property while having excellent steering stability.

The rubber composition according to the present invention, alkylene blocks of the styrene-alkylene block _{copolymer, - (CH 2 -CH (C} 2 H 5)) - units and _{(A) - (CH 2 -CH} 2) - It is preferable that the unit (B) is contained and the total content of the unit (A) is 40% by mass or more based on the total mass of the unit (A) and the unit (B).
As a result, it is possible to achieve both the WET performance and the low loss property while having excellent steering stability.

In a preferred embodiment, the alkylene block styrene-alkylene block _{copolymer, - (CH 2 -CH (C} 2 H 5)) - units (A) and - (CH ₂ -CH ₂₎ - units (B) And the total content of the units (A) is 50% by mass or more, 60% by mass or more, or 65% by mass or more, and 90% by mass with respect to the total mass of the units (A) and (B). Below, it is below 85 mass %, or below 80 mass %.

In one example of the rubber composition according to the present invention, the styrene/alkylene block copolymer is styrene/ethylene butylene/styrene block copolymer (SEBS), styrene/ethylene propylene/styrene block copolymer (SEPS) and styrene. -One or more selected from the group consisting of ethylene-ethylene propylene-styrene block copolymer (SEEPS).

In the rubber composition according to the present invention, the styrene/alkylene block copolymer is preferably a styrene/ethylenebutylene/styrene block copolymer.
As a result, it is possible to achieve both the WET performance and the low loss property while having excellent steering stability. The ethylene butylene block of the styrene/ethylene butylene/styrene block copolymer is a block having the above-mentioned ethylene unit and butylene unit.

The styrene/alkylene block copolymer may contain a constitutional unit other than the styrene block and the alkylene block. Examples of such other structural units, for _{example, - (CH 2 -CH (CH} = CH 2)) - , a structural unit having an unsaturated bond such as a unit and the like.

The method for preparing the styrene/alkylene block copolymer is not particularly limited, and a known method can be used. For example, by copolymerizing a styrene-based monomer such as styrene and a conjugated diene compound such as 1,3-butadiene or an olefin such as butene to obtain a precursor copolymer, and hydrogenating the precursor copolymer. A styrene/alkylene block copolymer can be obtained.

A commercially available product may be used as the styrene/alkylene block copolymer. Examples of such commercially available products include JSR DYNARON (registered trademark) 8903P and 9901P manufactured by JSR Corporation.

The compounding amount of the styrene/alkylene block copolymer in the rubber composition is not particularly limited and may be appropriately adjusted. For example, the compounding amount of the styrene/alkylene block copolymer is 4 to 30 parts by mass with respect to 100 parts by mass of the diene rubber component. From the viewpoint of more highly balancing WET performance, low loss property, and steering stability, the amount of the styrene/alkylene block copolymer is 8.5 to 30 with respect to 100 parts by mass of the diene rubber component. The amount is preferably 10 parts by mass, more preferably 10 to 30 parts by mass, still more preferably 12.5 to 30 parts by mass.

<Polyolefin softener>
In the present invention, the polyolefin-based softening agent is a softening agent containing at least one selected from the group consisting of alkene polymers and hydrogenated diene polymers. The polyolefin-based softener may be used alone or in combination of two or more.

The alkene polymer is, for example, a polymer of an alkene represented by the chemical formula C _n H _2n (n is an integer of 2 or more such as 2,3,4,5,6,7,8,9,10). Is mentioned. Examples of such alkenes include ethylene, propylene, 1-butene, cis-2-butene, trans-2-butene, 2-methylpropene (isobutene), 1-pentene, cis-2-pentene, trans-2. -Pentene and the like.

The alkene polymer is preferably polybutene (a polymer of isobutene), polyhexene, polyoctene, polyhexene/ethylene, polystyrene/ethylene.

Hydrogenated diene polymers are hydrogenated products of polymers of dienes. Examples of the diene include conjugated dienes such as 1,3-butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene, 2,4-hexadiene, 1,3-cyclopentadiene and 1,3-cyclohexadiene; Examples include non-conjugated dienes such as 1,4-pentadiene, 1,5-hexadiene, and 1,4-cyclohexadiene.

The hydrogenated diene polymer may or may not have a non-hydrogenated double bond. As an index of the degree of hydrogenation of the hydrogenated diene polymer, the iodine value (Ig/100g) is, for example, 50 or less, 30 or less, 25 or less, 20 or less or 15 or less.

The number average molecular weight of the alkene polymer and the hydrogenated diene polymer is, for example, 1,000 or more, or 1,500 or more, 100,000 or less, 10,000 or less, 9,000 or less, 8,000 or less, 7, It may be 000 or less, 6,000 or less, 5,000 or less, 4,000 or less, or 3,000 or less.

The polyolefin softener may or may not have a hydroxy group at the polymer terminal. From the viewpoint of improving the WET performance of the rubber composition, the polyolefin-based softening agent preferably does not have a hydroxy group at the polymer terminal.

A commercially available product may be used as the polyolefin softener. Examples of commercially available alkene polymers include LV-7, LV-50, LV-100, HV-15, HV-35, HV-50, and HV of Nisseki Polybutene, which is a polybutene manufactured by JXTG Energy Co., Ltd. -100, HV-300, HV-1900, SV-7000 and the like. Commercial products of hydrogenated diene polymers are, for example, hydrogenated polybutadiene manufactured by Nippon Soda Co., Ltd. under the trade names BI-2000, BI-3000, GI-1000, GI-2000, GI-3000, and polyolefins manufactured by Idemitsu Kosan Co., Ltd. The trade name is EPOL.

In one embodiment, the polyolefin softener is only one or more selected from the group consisting of alkene polymers and hydrogenated diene polymers.

The compounding amount of the polyolefin-based softening agent in the rubber composition is not particularly limited and may be appropriately adjusted. For example, the blending amount of the polyolefin-based softening agent is 5 to 30 parts by mass with respect to 100 parts by mass of the diene rubber component.

The rubber composition according to the present invention preferably contains 5 to 25 parts by mass of the polyolefin softener per 100 parts by mass of the diene rubber component.
As a result, the WET performance, the low loss property, and the steering stability can be more highly balanced.

<Reinforcing filler>
The rubber composition according to the present invention contains 45 parts by mass or more of the reinforcing filler per 100 parts by mass of the diene rubber component. If it is less than 45 parts by mass, the wear performance is deteriorated.

Examples of the reinforcing filler include silica, carbon black, aluminum hydroxide, clay, alumina, talc, mica, kaolin, glass balloon, glass beads, calcium carbonate, magnesium carbonate, magnesium hydroxide, magnesium oxide, titanium oxide, Examples thereof include potassium titanate and barium sulfate. The reinforcing filler may be used alone or in combination of two or more.

From the viewpoint of reinforcing property and low loss property, the reinforcing filler preferably contains silica.

The silica is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate.

The BET specific surface area of silica is not particularly limited and is, for example, 40 to 350 m ² /g, or 80 to 300 m ² /g, and preferably 150 to 280 m ² /g.

The amount of silica in the reinforcing filler is not particularly limited and can be appropriately adjusted depending on the purpose, but is preferably 50 to 100% by mass with respect to the total mass of the reinforcing filler, It is more preferably 80 to 100% by mass, and particularly preferably 90 to 100% by mass.

The carbon black is not particularly limited, and examples thereof include high, medium or low structure SAF, ISAF, ISAF-HS, IISAF, N339, HAF, FEF, GPF, and SRF grade carbon black.

Examples of the white filler other than silica include talc, aluminum hydroxide, clay, calcium carbonate and the like.

In the rubber composition according to the present invention, the reinforcing filler preferably contains silica and a white filler other than silica.
Thereby, the WET performance can be further improved.

The amount of the reinforcing filler compounded may be appropriately adjusted in the range of 45 parts by mass or more, and is, for example, 45 to 120 parts by mass with respect to 100 parts by mass of the diene rubber component. From the viewpoint of low loss and WET performance, the amount of the reinforcing filler compounded is preferably 50 to 100 parts by mass, more preferably 70 to 100 parts by mass, relative to 100 parts by mass of the diene rubber component. preferable.

The rubber composition according to the present invention includes a diene rubber component, a styrene/alkylene block copolymer, a polyolefin softening agent and a reinforcing filler, as well as a thermoplastic resin, a vulcanization accelerator, a silane coupling agent, and an additive. It may further contain one or more selected from the group consisting of a sulfurizing agent and a processability improving agent such as a polyethylene glycol-based compound or glycerin fatty acid ester.

<Thermoplastic resin>
The rubber composition according to the present invention may further contain a thermoplastic resin. Examples of the thermoplastic resin include C ₅ resin, C _{5 to} C ₉ resin, C ₉ resin, terpene resin, terpene-aromatic compound resin, rosin resin, dicyclopentadiene resin, alkylphenol resin. And those partially hydrogenated. The thermoplastic resins may be used alone or in combination of two or more.

-C ₅ resins -
The C ₅ type resin refers to a C ₅ type synthetic petroleum resin, and means a resin obtained by polymerizing a C ₅ fraction using a Friedel-Crafts type catalyst such as AlCl ₃ or BF ₃ . Specifically, a copolymer containing isoprene, cyclopentadiene, 1,3-pentadiene, 1-pentene and the like as a main component, a copolymer of 2-pentene and dicyclopentadiene, and a main component of 1,3-pentadiene And the like. These may be used alone or in combination of two or more.

-C ₅ -C ₉ resins -
The C _{5 to} C ₉ type resin refers to a C _{5 to} C ₉ type synthetic petroleum resin, and is obtained by polymerizing a C _{5 to} C ₁₁ fraction using a Friedel-Crafts type catalyst such as AlCl ₃ or BF _3. Means a resin. For example, a copolymer containing styrene, vinyltoluene, α-methylstyrene, indene or the like as a main component can be used. Among these, C _{5 to} C ₉ type resins having a small amount of C ₉ or more components are preferable because they have excellent compatibility with the diene rubber component. Specifically, a resin in which the proportion of C ₉ or more components in the C _{5 to} C ₉ based resin is less than 50 mass% is preferable, and a resin in which 40 mass% or less is more preferable. Further, those partially hydrogenated (for example, Alcon (registered trademark) manufactured by Arakawa Chemical Industry Co., Ltd.) are also included. These may be used alone or in combination of two or more.

-C ₉ resins -
The C ₉ type resin refers to a C ₉ type synthetic petroleum resin, and means a resin obtained by polymerizing a C ₉ fraction using a Friedel-Crafts type catalyst such as AlCl ₃ or BF ₃ . Examples thereof include copolymers containing indene, methylindene, α-methylstyrene, vinyltoluene and the like as main components. Further, those partially hydrogenated (for example, Alcon (registered trademark) manufactured by Arakawa Chemical Industry Co., Ltd.) are also included. These may be used alone or in combination of two or more.

-Terpene resin-
The terpene-based resin can be obtained by blending turpentine oil obtained at the same time when rosin is obtained from a pine tree or a polymerization component separated therefrom, and polymerizing using a Friedel-Crafts type catalyst. Examples thereof include β-pinene resin and α-pinene resin. These may be used alone or in combination of two or more.

-Terpene-Aromatic Compound Resin-
The terpene-aromatic compound-based resin can be obtained by reacting a terpene with various phenols using a Friedel-Crafts type catalyst or further condensing with formalin. For example, terpene-phenol resin and the like can be mentioned. Among the terpene-phenol resins, a resin having a phenol component in the terpene-phenol resin of less than 50% by mass is preferable, and a resin of 40% by mass or less is more preferable. These may be used alone or in combination of two or more.

The terpene as a raw material is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include monoterpene hydrocarbons such as α-pinene and limonene. Among these, those containing α-pinene are preferable, and α-pinene is more preferable.

-Rosin resin-
The rosin-based resin is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include natural resin rosin such as gum rosin contained in raw pine resin and tall oil, tall oil resin, wood rosin; modified rosin; modified Examples include rosin derivatives. Specific examples of the modified rosin derivative include polymerized rosin, partially hydrogenated rosin thereof; glycerin ester rosin, partially hydrogenated rosin thereof and fully hydrogenated rosin; pentaerythritol ester rosin, partially hydrogenated rosin thereof and fully hydrogenated rosin. And so on. These may be used alone or in combination of two or more.

-Dicyclopentadiene resin-
The dicyclopentadiene resin can be obtained by polymerizing dicyclopentadiene using a Friedel-Crafts type catalyst such as AlCl ₃ or BF ₃ . Specific examples of commercial products of dicyclopentadiene resin include Quinton 1920 (manufactured by Nippon Zeon Co., Ltd.), Quinton 1105 (manufactured by Nippon Zeon Co., Ltd.), Marcarets M-890A (manufactured by Maruzen Petrochemical Co., Ltd.) and the like. These may be used alone or in combination of two or more.

-Alkylphenol resin-
The alkylphenol-based resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include alkylphenol-acetylene resins such as p-tert-butylphenol-acetylene resins and low-polymerization degree alkylphenol-formaldehyde resins. Be done. These may be used alone or in combination of two or more.

The blending amount of the thermoplastic resin is not particularly limited and may be appropriately adjusted.

The rubber composition according to the present invention preferably further contains 1 to 70 parts by mass, more preferably 5 to 30 parts by mass, and 5 to 20 parts by mass of the thermoplastic resin per 100 parts by mass of the diene rubber component. More preferable.
Thereby, the WET performance can be further improved.

<Vulcanization accelerator>
The rubber composition according to the present invention preferably contains a vulcanization accelerator. The vulcanization accelerator is, for example, at least one selected from guanidines, sulfenamides, thiazoles, thiourea, and diethylthiourea. Each of these may be used alone or in combination of two or more.

The compounding amount of the vulcanization accelerator is not particularly limited and can be appropriately adjusted according to the purpose, and is, for example, 0.1 to 20 parts by mass with respect to 100 parts by mass of the diene rubber component. When the amount is 0.1 parts by mass or more, the effect of vulcanization is easily obtained, and when the amount is 20 parts by mass or less, excessive progress of vulcanization can be suppressed.

-Guanidines-
The guanidines are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide and dicatechol. Examples thereof include di-o-tolylguanidine salt of borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine. Be done. Among these, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine and 1-o-tolylbiguanide are preferable, and 1,3-diphenylguanidine is more preferable, from the viewpoint of high reactivity.

-Sulfenamides-
The sulfenamides are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include N-cyclohexylbenzothiazole-2-sulfenamide and N,N-dicyclohexyl-2-benzothiazolylsulfene. Amide, N-tert-butylbenzothiazole-2-sulfenamide, N-oxydiethylene-2-benzothiazolylsulfenamide, N-methyl-2-benzothiazolylsulfenamide, N-ethyl-2-benzo Thiazolyl sulfenamide, N-propyl-2-benzothiazolyl sulfenamide, N-butyl-2-benzothiazolyl sulfenamide, N-pentyl-2-benzothiazolyl sulfenamide, N-hexyl-2 -Benzothiazolyl sulfenamide, N-octyl-2-benzothiazolyl sulfenamide, N-2-ethylhexyl-2-benzothiazolyl sulfenamide, N-decyl-2-benzothiazolyl sulfenamide, N -Dodecyl-2-benzothiazolyl sulfenamide, N-stearyl-2-benzothiazolyl sulfenamide, N,N-dimethyl-2-benzothiazolyl sulfenamide, N,N-diethyl-2-benzothia Zolylsulfenamide, N,N-dipropyl-2-benzothiazolylsulfenamide, N,N-dibutyl-2-benzothiazolylsulfenamide, N,N-dipentyl-2-benzothiazolylsulfenamide, N,N-dihexyl-2-benzothiazolyl sulfenamide, N,N-dioctyl-2-benzothiazolyl sulfenamide, N,N-di-2-ethylhexylbenzothiazolyl sulfenamide, N,N- Examples thereof include didodecyl-2-benzothiazolyl sulfenamide and N,N-distearyl-2-benzothiazolyl sulfenamide. Among these, N-cyclohexylbenzothiazole-2-sulfenamide and N-tert-butylbenzothiazole-2-sulfenamide are preferable because of their high reactivity.

-Thiazoles-
The thiazoles are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include 2-mercaptobenzothiazole, benzothiazole disulfide, zinc salt of 2-mercaptobenzothiazole, and cyclohexylamine of 2-mercaptobenzothiazole. Salt, 2-(N,N-diethylthiocarbamoylthio)benzothiazole, 2-( ^4' -morpholinodithio)benzothiazole, 4-methyl-2-mercaptobenzothiazole, di-(4-methyl-2-benzothiazolyl) Disulfide, 5-chloro-2-mercaptobenzothiazole, 2-mercaptobenzothiazole sodium, 2-mercapto-6-nitrobenzothiazole, 2-mercapto-naphtho[1,2-d]thiazole, 2-mercapto-5-methoxy Examples thereof include benzothiazole and 6-amino-2-mercaptobenzothiazole. Among these, 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide are preferable because of their high reactivity.

-Thiourea-
Thiourea is a compound represented by NH ₂ CSNH ₂ .

-Diethylthiourea-
Diethylthiourea is a compound represented by C ₂ H ₅ NHCSNHC ₂ H ₅ .

<Silane coupling agent>
By using the silane coupling agent, for example, it is possible to obtain a tire that is more excellent in workability during rubber processing and has better wear resistance. The silane coupling agent may be used alone or in combination of two or more.

The silane coupling agent is not particularly limited and may be appropriately selected depending on the intended purpose, for example, formula ^{(I) :( R 1 O)} 3-p (R 2) p Si-R 3 -S a _{^{-R 3 -Si (OR 1) 3}} -r (R 2) compounds represented by _r, the formula ^{(II) :( R 4 O)} 3-s (R 5) s Si-R 6 -S k -R 7 such as _{^{-S k -R 6 -Si (OR 4}} ) 3-t (R 5) the compound represented by _t, and the like.

In formula (I), each R ¹ is independently a linear, cyclic or branched alkyl group having 1 to 8 carbon atoms, a linear or branched alkoxyalkyl group having 2 to 8 carbon atoms, or a hydrogen atom, R ² is independently a linear, cyclic or branched alkyl group having 1 to 8 carbon atoms, and R ³ is independently a linear or branched alkylene group having 1 to 8 carbon atoms. a has an average value of 2 to 6, p and r may be the same or different, and each has an average value of 0 to 3. However, both p and r are not 3.

In formula (II), each R ⁴ is independently a linear, cyclic or branched alkyl group having 1 to 8 carbon atoms, a linear or branched alkoxyalkyl group having 2 to 8 carbon atoms, or a hydrogen atom, ⁵ is independently a linear, cyclic or branched alkyl group having 1 to 8 carbon atoms, and R ⁶ is independently a linear or branched alkylene group having 1 to 8 carbon atoms. R ⁷ is one of the general formulas (-S-R ⁸ -S-), (-R ⁹ -S _{m 1} -R ¹⁰ -) and (-R ¹¹ -S _{m 2} -R ¹² -S _{m 3} -R ¹³ -). be a divalent group (R ⁸ to R ¹³ are each a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent organic group containing a divalent aromatic group, or a sulfur, and hetero element other than oxygen, , M1, m2 and m3 may be the same or different and each has an average value of 1 or more and less than 4), k is independently an average value of 1 to 6, and s and t are each The average value is 0 to 3. However, both s and t are never 3.

Examples of the silane coupling agent represented by the formula (I) include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(3-methyldimethoxysilylpropyl)tetrasulfide. Sulfide, bis(2-triethoxysilylethyl) tetrasulfide, bis(3-triethoxysilylpropyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(3-methyldimethoxysilylpropyl) disulfide, bis(2 -Triethoxysilylethyl) disulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(3-trimethoxysilylpropyl) trisulfide, bis(3-methyldimethoxysilylpropyl) trisulfide, bis(2-triethoxy) Silylethyl) trisulfide, bis(3-monoethoxydimethylsilylpropyl) tetrasulfide, bis(3-monoethoxydimethylsilylpropyl) trisulfide, bis(3-monoethoxydimethylsilylpropyl) disulfide, bis(3-monomethoxy Dimethylsilylpropyl) tetrasulfide, bis(3-monomethoxydimethylsilylpropyl) trisulfide, bis(3-monomethoxydimethylsilylpropyl) disulfide, bis(2-monoethoxydimethylsilylethyl) tetrasulfide, bis(2-mono Examples thereof include ethoxydimethylsilylethyl) trisulfide and bis(2-monoethoxydimethylsilylethyl) disulfide.

The silane coupling agents represented by Formula (II), for example, the average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S 2 - (CH 2) 6 -S 2 - (CH 2 _{) 3 -Si (OCH 2 CH 3} ) 3, the average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S 2 - (CH 2) 10 -S 2 - (CH 2) 3 -Si (OCH ₂ CH _{3) 3,} the average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S 3 - (CH 2) 6 -S 3 - (CH 2) 3 -Si (OCH 2 CH _{3) 3,} the average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S 4 - (CH 2) 6 -S 4 - (CH 2) 3 -Si (OCH 2 CH 3) 3, average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S- (CH 2) 6 -S 2 - (CH 2) 6 -S- (CH 2) 3 -Si (OCH 2 CH 3 ) _3, the average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S- (CH 2) 6 -S 2.5 - (CH 2) 6 -S- (CH 2) 3 -Si (OCH ₂ CH _{3) 3,} the average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S- (CH 2) 6 -S 3 - (CH 2) 6 -S- (CH 2) 3 - _{Si (OCH 2 CH 3) 3} , the average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S- (CH 2) 6 -S 4 - (CH 2) 6 -S- (CH 2 _{) 3 -Si (OCH 2 CH 3} ) 3, the average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S- (CH 2) 10 -S 2 - (CH 2) 10 -S- _{(CH 2) 3 -Si (OCH} 2 CH 3) 3, the average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S 4 - (CH 2) 6 -S 4 - (CH 2) _{6 -S 4 - (CH 2)} 3 -Si (OCH 2 CH 3) 3, the average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S 2 _{- (CH 2) 6 -S 2} - (CH 2) 6 -S 2 - (CH 2) 3 -Si (OCH 2 CH 3) 3, the average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2 _{) 3 -S- (CH 2) 6} -S 2 - (CH 2) 6 -S 2 - (CH 2) such as _{6 -S- (CH 2) 3 -Si} (OCH 2 CH 3) 3 having a can Can be mentioned.

Examples of the silane coupling agent include Si363 (ethoxy(3-mercaptopropyl)bis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silane, [C ₁₃ H manufactured by Evonik Degussa. ₂₇ O(CH ₂ CH ₂ O) ₅ ] ₂ (CH ₃ CH ₂ O)Si(CH ₂ ) ₃ SH) and the like.

The compounding amount of the silane coupling agent may be appropriately adjusted, but is, for example, 2 parts by mass or more based on 100 parts by mass of the diene rubber component. From the viewpoint of improving the reactivity of silica, the amount is preferably 2 to 20 parts by mass, and more preferably 4 to 12 parts by mass, relative to 100 parts by mass of the diene rubber component.

The ratio of the compounding amount (mass) of the silane coupling agent to the compounding amount (mass) of silica (the compounding amount of the silane coupling agent/the compounding amount of silica) is not particularly limited and may be appropriately adjusted according to the purpose. However, 0.01 to 0.20 is preferable, 0.03 to 0.20 is more preferable, and 0.04 to 0.10 is particularly preferable. When the ratio is 0.01 or more, the effect of improving the low loss property of the rubber composition is easily obtained, and when the ratio is 0.20 or less, the manufacturing cost of the rubber composition is reduced and the economical efficiency is improved. Can be made

<Vulcanizing agent>
The vulcanizing agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include sulfur. The vulcanizing agents may be used alone or in combination of two or more.

The compounding amount of the vulcanizing agent is not particularly limited and may be appropriately adjusted depending on the purpose, for example, 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the diene rubber component, 1.0 to 2.0 parts by mass is more preferable, and 1.2 to 1.8 parts by mass is particularly preferable.

<Glycerin fatty acid ester>
When the rubber composition of the present invention contains silica as a reinforcing filler, it is preferable that the rubber composition further contains the glycerin fatty acid ester described in JP-A-2016-160424 and JP-A-2016-160423. When the glycerin fatty acid ester is contained, the processability of the rubber composition is improved, and the low loss property of the tire can be further improved by applying the rubber composition to the tire.

In the rubber composition of the present invention, the blending amount of the glycerin fatty acid ester is preferably 0.5 parts by mass or more, and more preferably 1 part by mass with respect to 100 parts by mass of silica from the viewpoint of processability of the rubber composition. As described above, more preferably 1.5 parts by mass or more, and from the viewpoint of the fracture characteristics of the rubber composition, preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and further preferably 10 parts by mass or less with respect to 100 parts by mass of silica. It is preferably 5 parts by mass or less.

<Other ingredients>
The rubber composition according to the present invention, in addition to the above-mentioned components, components that are usually used in the rubber industry, such as antioxidants, vulcanization accelerators, organic acid compounds, etc., do not violate the spirit of the present invention. The content can be appropriately selected within the range.

(Method for preparing rubber composition)
The method for preparing the rubber composition according to the present invention is not particularly limited, and by using a known kneading method, components such as a diene rubber component, a styrene/alkylene block copolymer, a polyolefin softener, and a reinforcing filler are added. Just knead.

The use of the rubber composition according to the present invention is not particularly limited, but it can be used, for example, in a tire or the like.

The rubber composition according to the present invention is preferably for tires.
As a result, the WET performance of the tire, the low loss property, and the steering stability can be highly balanced.

The rubber composition according to the present invention is more preferably used for tire treads.

(tire)
The tire according to the present invention is a tire using any one of the rubber compositions described above.
As a result, the WET performance of the tire, the low loss property, and the steering stability can be highly balanced.

The application site of the rubber composition in the tire is not particularly limited, but it is preferably used in the tread rubber of the tire.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are intended to illustrate the present invention and do not limit the present invention in any way.

The materials used in the examples are as follows.
Natural rubber (NR): RSS#3
Styrene-butadiene rubber (low TgSBR): Styrene-butadiene rubber synthesized by the method described below (high TgSBR): Weight-average molecular weight synthesized by the method described below, containing 37.5 parts by mass of an oil component relative to 100 parts by mass of the rubber component. (Mw)=85.2×10 ⁴ , molecular weight of 200×10 ⁴ or more and 500×10 ⁴ or less=4.6%, shrinkage factor (g′)=0.57, glass transition temperature (Tg)=−24 ℃
Styrene/alkylene block copolymer (total styrene content 15% by mass): DYNARON (registered trademark) 8600P manufactured by JSR, ratio of unit (A) to total mass of units (A) and units (B)=68% by mass
Styrene/alkylene block copolymer (total styrene content 35% by mass): DYNARON (registered trademark) 8903P manufactured by JSR, ratio of unit (A) to total mass of unit (A) and unit (B)=70% by mass
Silica: Trade name NipSil (registered trademark) AQ manufactured by Tosoh Silica Co., Ltd.
Carbon black: product name #80 manufactured by Asahi Carbon Co., Ltd.
Silane coupling agent: ethoxy(3-mercaptopropyl)bis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silane, trade name Si363 manufactured by Evonik Degussa.
C ₅ ~C _9-based resin (C5-C9 resin): JXTG Energy's trade name T-REZ RD104
C ₉ resins (C9 resin): JXTG Energy's (trade name) manufactured by Nippon Oil Neo polymer 140
Wax: Microcrystalline wax, trade name Ozoace 0701 manufactured by Nippon Seiro Co., Ltd.
Anti-aging agent (6PPD): N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, trade name Nocrac 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Vulcanization accelerator (DPG): 1,3-diphenylguanidine, trade name Nox Cellar D manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Vulcanization accelerator (MBTS): benzothiazole disulfide, trade name NOXCELLER DM manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Vulcanization accelerator (CBS): N-cyclohexylbenzothiazole-2-sulfenamide, trade name Sanseller CM-G manufactured by Sanshin Chemical Industry Co., Ltd.

Synthesis of modified SBR (low Tg SBR) A cyclohexane solution of 1,3-butadiene and a cyclohexane solution of styrene were placed in a dry, nitrogen-substituted 800 mL pressure-resistant glass container to give 67.5 g of 1,3-butadiene and 7.5 g of styrene. Then, 0.6 mmol of 2,2-ditetrahydrofurylpropane and 0.8 mmol of n-butyllithium are added, and then polymerization is performed at 50° C. for 1.5 hours. At this time, 0.72 mmol of N,N-bis(trimethylsilyl)-3-[diethoxy(methyl)silyl]propylamine was added as a modifier to the polymerization reaction system in which the polymerization conversion rate became almost 100%. Perform a denaturation reaction at 30° C. for 30 minutes. Then, 2 mL of a 5% by mass solution of 2,6-di-t-butyl-p-cresol (BHT) in isopropanol was added to stop the reaction, and the reaction product was dried according to a conventional method to obtain a modified SBR. The microstructure of the modified SBR has a bound styrene content of 10% by mass, a butadiene portion having a vinyl bond content of 40%, and a peak molecular weight of 200,000.

Synthesis of modified SBR (high TgSBR1) The internal volume is 10 L, the ratio of internal height (L) to diameter (D) (L/D) is 4.0, and the inlet is at the bottom and the outlet is at the top. Then, a tank-type pressure vessel having a stirrer which is a tank-type reactor with a stirrer and a jacket for temperature control is used as a polymerization reactor. Water is removed in advance, and 1,3-butadiene is mixed under the conditions of 17.9 g/min, styrene is 9.8 g/min, and n-hexane is 145.3 g/min. In a static mixer provided in the middle of a pipe for supplying the mixed solution to the inlet of the reaction group, 0.117 mmol/min of residual impurity inactivating n-butyllithium was added and mixed at the bottom of the reaction group. Supply continuously. Further, 2,2-bis(2-oxolanyl)propane as a polar substance is vigorously mixed with a stirrer at a rate of 0.0194 g/min and n-butyllithium as a polymerization initiator at a rate of 0.242 mmol/min. It is supplied to the bottom of the polymerization reactor to continuously continue the polymerization reaction. The temperature is controlled so that the temperature of the polymerization solution at the outlet of the top of the reactor is 75°C. When the polymerization was sufficiently stable, a small amount of the polymer solution before addition of the coupling agent was withdrawn from the outlet of the top of the reactor, and the antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of the polymer, and then the solvent was added. Remove and measure Mooney viscosity at 110° C. and various molecular weights. Next, 0.0302 mmol/min of tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine diluted to 2.74 mmol/L as a coupling agent was added to the polymer solution flowing out from the outlet of the reactor. A polymer solution to which a coupling agent has been added is continuously added at a rate of water containing 5.2 ppm of water (n-hexane solution) and mixed by passing through a static mixer to cause a coupling reaction. At this time, the time until the coupling agent was added to the polymerization solution flowing out from the outlet of the reactor was 4.8 minutes, and the temperature was 68° C. The temperature in the polymerization step and the temperature until the modifier was added were Is 7°C. The antioxidant (BHT) was continuously added to the polymer solution subjected to the coupling reaction at 0.055 g/min (n-hexane solution) so that the amount was 0.2 g per 100 g of the polymer, and the coupling reaction was completed. To do. Simultaneously with the antioxidant, an oil (JOMO Process NC140, manufactured by JX Nippon Mining & Nisseki Energy Co., Ltd.) was continuously added to 100 g of the polymer in an amount of 37.5 g, and mixed with a static mixer. The solvent is removed by steam stripping to obtain the modified SBR.

<Examples 1 to 10 and Comparative Examples 1 to 6>
A rubber composition is prepared according to the formulation (parts by mass) shown in Tables 1 and 2. Using the rubber composition as a tread rubber, a radial tire for passenger cars having a size of 195/65R15 is produced according to a conventional method.

(Performance evaluation)
<WET performance>
For each test tire, the test driver makes various runs on the course of the wet road, and makes a feeling evaluation on the running performance of the running tire. The WET performance of Comparative Example 1 is set to 100 and displayed as an index. The evaluation is shown in Table 2. The larger the index value, the better the WET performance of the tire.

<Low loss>
For the vulcanized rubber obtained by vulcanizing each rubber composition at 145° C. for 33 minutes, the loss tangent (tan δ) was measured by a Ueshima Seisakusho spectrometer, temperature 50° C., initial strain 2%, dynamic strain 1%, frequency. It is measured under the condition of 52 Hz. The reciprocal of tan δ of Comparative Example 1 is set to 100 and displayed as an index. The evaluation is shown in Table 2. The larger the index value, the better the low loss property.

<Steering stability>
For each test tire, the driving stability is evaluated based on the feeling of the test driver in the actual vehicle test on the dry road surface. The steering stability of Comparative Example 1 is indexed to 100. The evaluation is shown in Table 2. The larger the index value, the better the steering stability of the tire.

As shown in Table 2, the rubber composition according to the present invention can highly balance the WET performance, the low loss property, and the steering stability.

According to the present invention, it is possible to provide a rubber composition in which the WET performance, the low loss property, and the steering stability are highly balanced. According to the present invention, it is possible to provide a tire in which the WET performance, the low loss property, and the steering stability are highly balanced.

Claims (9)

Including a diene rubber component, a styrene/alkylene block copolymer, a polyolefin softener, and a reinforcing filler,
The total styrene content of the styrene/alkylene block copolymer is 30% by mass or more based on the total mass of the styrene/alkylene block copolymer,
The polyolefin-based softener contains at least one selected from the group consisting of alkene polymers and hydrogenated diene polymers,
A rubber composition containing 45 parts by mass or more of the reinforcing filler per 100 parts by mass of the diene rubber component. The alkylene block of the styrene/alkylene block copolymer has —(CH ₂ —CH(C ₂ H ₅ ))-unit (A) and —(CH ₂ —CH ₂ )-unit (B), The rubber composition according to claim 1, wherein the total content of the units (A) is 40% by mass or more based on the total mass of the units (A) and the units (B). The rubber composition according to claim 1, comprising 5 to 25 parts by mass of the polyolefin-based softening agent per 100 parts by mass of the diene rubber component. The rubber composition according to claim 1, wherein the diene rubber component contains 40 parts by mass or more of natural rubber per 100 parts by mass of the diene rubber component. Furthermore, the rubber composition according to any one of claims 1 to 4, which contains 1 to 70 parts by mass of a thermoplastic resin per 100 parts by mass of the diene rubber component. The rubber composition according to any one of claims 1 to 5, wherein the reinforcing filler contains silica and a white filler other than silica. The rubber composition according to any one of claims 1 to 6, which is for a tire. The rubber composition according to any one of claims 1 to 7, which is for a tread of a tire. A tire using the rubber composition according to any one of claims 1 to 8.