JP6736955B2 - tire - Google Patents

Description

The present invention relates to a pneumatic tire having a tread composed of a predetermined rubber composition.

In recent years, there has been a strong demand for low fuel consumption of automobiles due to an increase in interest in environmental problems, and development of tires that reduce rolling resistance of tires and suppress heat generation is being promoted. Among the tire members, excellent fuel economy is required especially for a tread having a high occupancy ratio in the tire. Further, grip performance and abrasion resistance are required as the original performance of the tread.

Generally, it is effective to reduce energy loss of a rubber composition in order to improve fuel economy. On the other hand, in order to improve grip performance, methods such as increasing the amount of silica, increasing the ratio of softening agents such as oil, and increasing the glass transition temperature of a rubber composition by blending a resin have been used. According to the method, energy loss is increased and fuel economy is deteriorated. That is, there is a trade-off relationship between low fuel consumption and grip performance, and it has been difficult to achieve both at the same time. In addition, by increasing the elongation of the rubber by blending a large particle size inorganic filler such as calcium carbonate, magnesium oxide, etc., it is possible to improve the trackability with the road surface without increasing energy loss and improve the grip performance. Although being studied, these inorganic fillers having a large particle size are inferior in reinforcing property, and thus there is a problem that abrasion resistance becomes insufficient. Thus, it has been difficult to improve fuel economy, grip performance, and wear resistance in a well-balanced manner.

In Patent Document 1, by blending a rubber component having a low glass transition temperature with aluminum hydroxide having specific physical properties, it is possible to improve fuel economy and wet grip performance without lowering workability and wear resistance. Tread rubber compositions are described. Further, it is also described that the reinforcing property of aluminum hydroxide is enhanced by adding a silane coupling agent. However, there is room for improvement in terms of achieving both wear resistance, low fuel consumption, and grip performance.

JP 2001-181447 A

An object of the present invention is to provide a tire having excellent grip performance while maintaining wear resistance and low fuel consumption.

The first invention of the present invention relates to a tire provided with a tread composed of a rubber composition containing a hydroxide of a Group 13 element other than aluminum hydroxide and a coupling agent.

The second invention of the present invention is a rubber composition containing a hydroxide of a Group 13 element and a coupling agent, and a rubber composition containing no hydroxide of a Group 13 element, The present invention relates to a tire having a tread having a rubber hardness of -3 to +3 and an elongation at break of 103% or more.

<First invention>
The tire of the first invention comprises a tread composed of a rubber composition containing a hydroxide of a Group 13 element other than aluminum hydroxide and a coupling agent for a diene rubber component. To do.

The diene rubber component is not particularly limited, and examples thereof include natural rubber (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), styrene butadiene rubber (SBR), butadiene rubber (BR), acrylonitrile butadiene rubber. (NBR), chloroprene rubber (CR), butyl rubber (IIR) and the like which are common in the rubber industry can be used. These rubber components may be used alone or in combination of two or more. The rubber component may be appropriately selected according to the required performance, and for example, NR, ENR, SBR, BR are preferable.

The NR is not particularly limited, and those commonly used in the rubber industry such as SIR20, RSS#3 and TSR20 can be used. The ENR is not particularly limited, and commercially available products such as ENR25 and ENR50 manufactured by MRB (Malaysia) may be used, or NR may be epoxidized and used.

The content of 100% by mass of the rubber component in the case of containing NR and/or ENR is preferably 5% by mass or more and more preferably 10% by mass or more, because sufficient strength can be obtained. Further, in order to improve crack growth resistance, ozone resistance, abrasion resistance and the like, it is preferable to use in combination with other rubber components, so the content of NR and/or ENR is preferably 90% by mass or less, 70 mass% or less is more preferable.

The SBR is not particularly limited, and unmodified solution-polymerized SBR (S-SBR), unmodified emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR) and the like. Among them, the modified SBR is preferable because it is highly effective in improving grip performance, fuel economy and steering stability.

The modified SBR is preferably one that is coupled with tin, a silicon compound or the like. As a method for coupling the modified SBR, for example, an alkali metal (such as Li) or an alkaline earth metal (such as Mg) at the molecular chain end of the modified SBR is reacted with tin halide, silicon halide or the like according to a conventional method. Method etc. are mentioned.

The modified SBR is also preferably a copolymer of styrene and butadiene, which has a primary amino group or an alkoxysilyl group. The primary amino group may be bonded to any of the polymerization initiation terminal, the polymerization termination terminal, the polymer main chain, and the side chain, but it suppresses energy loss from the polymer terminal and improves energy loss characteristics. From the viewpoint of obtaining it, it is preferably introduced at the polymerization initiation terminal or the polymerization termination terminal.

（化学式（１）中、Ｒ¹、Ｒ²およびＲ³は、同一もしくは異なって、アルキル基、アルコキシ基、シリルオキシ基、アセタール基、カルボキシル基、メルカプト基（−ＳＨ）またはこれらの誘導体を表す。Ｒ⁴およびＲ⁵は、同一もしくは異なって、水素原子またはアルキル基を表す。ｍは整数を表す。） Among these modified SBRs, it is easy to control the molecular weight of the polymer, and it is possible to reduce the amount of low molecular weight components that increase rolling resistance. Furthermore, the bond between the reinforcing agent and the polymer chain is strengthened, and grip performance, fuel economy and steering stability are improved. The modified S-SBR obtained by modifying the polymerization end (active end) of the solution-polymerized styrene-butadiene rubber (S-SBR) with a nitrogen-containing compound such as a compound represented by the following chemical formula (1) for the reason that the property can be further improved. (Modified SBR described in JP 2010-111753 A) is preferably used.

(In the chemical formula (1), R ¹ , R ² and R ³ are the same or different and each represent an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group, a mercapto group (—SH) or a derivative thereof. R ⁴ and R ⁵ are the same or different and each represent a hydrogen atom or an alkyl group, and m represents an integer.)

The alkyl group of R ¹ , R ² and R ³ is preferably an alkyl group having 1 to 4 carbon atoms.

The alkoxy group of R ¹ , R ² and R ³ is preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 6 carbon atoms, and still more preferably an alkoxy group having 1 to 4 carbon atoms.

The acetal group of R ¹ , R ² and R ³ is preferably an acetal group having 1 to 8 carbon atoms.

The alkyl group of R ⁴ and R ⁵ is preferably an alkyl group having 1 to 4 carbon atoms.

m represents an integer, preferably 1 to 5, more preferably 2 to 4, and even more preferably 3.

Examples of the compound represented by the chemical formula (1) include 3-aminopropyltrimethoxysilane, 3-aminopropyldimethylmethoxysilane, 3-aminopropylmethyldimethoxysilane, 2-dimethylaminoethyltrimethoxysilane, and 3-diethylaminopropyltrimethoxysilane. Examples thereof include methoxysilane and 3-dimethylaminopropyltrimethoxysilane. These may be used alone or in combination of two or more. Among them, as the compound represented by the chemical formula (1) used for the modified SBR, R ¹ , R ² and R ³ are alkoxy groups and R ¹ and R ³ are alkoxy groups, because excellent grip performance and fuel economy can be obtained. ^A compound in which ⁴ and R ⁵ are hydrogen atoms (3-aminopropyltrimethoxysilane) is preferable.

A method for modifying SBR with a compound (modifying agent) represented by the chemical formula (1) is described in Japanese Patent Publication No. 6-53768, Japanese Patent Publication No. 6-57767, and Japanese Patent Publication No. 2003-514078. A conventionally known method such as a method can be used. For example, SBR and a modifying agent may be brought into contact with each other. After synthesizing SBR by anionic polymerization, a predetermined amount of the modifying agent is added to the polymer rubber solution, and the polymerization end (active end) of SBR and the modifying agent are added. And a method of reacting by adding a modifier to the BR solution.

From the viewpoint of grip performance, the styrene content of SBR is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 30% by mass or more. Further, the styrene content of SBR is preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 45% by mass or less, because the ground contact area with the road surface is increased and high grip performance is obtained. .. The styrene content of SBR in this specification is a value calculated by ¹ H-NMR measurement.

From the viewpoint of ensuring grip performance, the vinyl bond content of SBR is preferably 5 mol% or more, more preferably 10 mol% or more, and further preferably 15 mol% or more. The vinyl bond content of SBR is preferably 60 mol% or less, more preferably 55 mol% or less, and further preferably 50 mol% or less, from the viewpoint of wear resistance and fuel economy. In addition, the vinyl bond amount of SBR in this specification shows the vinyl bond amount of a butadiene part, and is a value calculated by ¹ H-NMR measurement.

From the viewpoint of grip performance, the content of 100% by mass of the rubber component in the case of containing SBR is preferably 20% by mass or more, more preferably 50% by mass or more, further preferably 70% by mass or more, and 100% by mass. Particularly preferred. The upper limit of the SBR content is not particularly limited, but when it is used in combination with another rubber component, it is preferably 90% by mass or less. When SBR is an oil-extended product to which oil is added, the content of SBR indicates the content of SBR (rubber solid content) excluding the oil content.

The BR is not particularly limited, and unmodified butadiene rubber such as high-cis 1,4-polybutadiene rubber (high-cis BR) and butadiene rubber containing 1,2-syndiotactic polybutadiene crystals (SPB-containing BR); modified butadiene rubber ( Modified BR) and the like.

The high cis BR is a butadiene rubber having a cis 1,4 bond content of 90 mass% or more. Examples of commercially available products of such a high cis BR include BR1220 manufactured by Nippon Zeon Co., Ltd., UBEPOL BR130B and BR150B manufactured by Ube Industries.

The SPB-containing BR is preferably not one in which 1,2-syndiotactic polybutadiene crystals are simply dispersed in BR, but one that is chemically bonded to BR and then dispersed. Commercially available products of such SPB-containing BR include VCR303, VCR412, VCR617 manufactured by Ube Industries, Ltd., and the like.

The modified BR is obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and the terminal of the modified BR molecule is further bound by a tin-carbon bond; Examples thereof include those modified with a nitrogen-containing compound such as the compound represented by the chemical formula (1).

The method for modifying BR with the compound (modifying agent) represented by the chemical formula (1) is the same as the method for modifying SBR described above. For example, BR and the modifying agent may be brought into contact with each other, and BR is modified by anionic polymerization. After synthesizing, a predetermined amount of a modifier is added to the polymer rubber solution, and a polymerization terminal (active terminal) of BR is reacted with the modifier, a method of adding the modifier to the BR solution and reacting Are listed.

Among these various BRs, it is preferable to use unmodified high cis BR having a cis 1,4 bond content of 90% by mass or more because it has good wear resistance and fuel economy.

When BR is contained, the content thereof in 100% by mass of the rubber component is preferably 5% by mass or more, and more preferably 8% by mass or more, because it is excellent in abrasion resistance and steering stability. Further, the content of BR is preferably 15% by mass or less, and more preferably 10% by mass or less, from the viewpoint of low fuel consumption.

The hydroxide of a Group 13 element other than aluminum hydroxide reacts with a coupling agent in the same manner as silica or carbon black to form a bond of polymer-coupling agent-hydroxide of Group 13 element. Exhibits the same reinforcing properties as silica and carbon black. Group 13 element hydroxides have fewer reaction points and are easier to move than silica or carbon black, so rubber compositions containing Group 13 element hydroxides are supple and stretch well, and have good grip performance and steering stability. Excellent in Further, since it is not a conventional method for improving grip performance by increasing energy loss, there is no problem that fuel economy is deteriorated. Further, as mentioned above, the hydroxide of the 13th group element has the same reinforcing property as silica and carbon black, so that the grip performance is improved by adding a large particle size inorganic filler such as conventional calcium carbonate or magnesium oxide. The problem that the abrasion resistance becomes insufficient due to the above method does not occur. Therefore, it is possible to provide a rubber composition having improved grip performance without deteriorating wear resistance and fuel economy.

Examples of the hydroxide of Group 13 element include aluminum hydroxide, gallium hydroxide, indium hydroxide, thallium hydroxide, and the like. The rubber composition according to the first invention is a Group 13 element except aluminum hydroxide. Contains elemental hydroxide. Among the hydroxides of Group 13 elements other than aluminum hydroxide, indium hydroxide is preferable because it has a large particle size and the rubber composition is easily stretched.

From the viewpoint of wear resistance, the nitrogen adsorption specific surface area (N ₂ SA) of hydroxides of Group 13 elements other than aluminum hydroxide is preferably 5 m ² /g or more, more preferably 10 m ² /g or more. Also, N ₂ SA of hydroxides of Group 13 elements except aluminum hydroxide, from the viewpoint of dispersibility, preferably less than 30 m ² / g, more preferably 25 m ² / g or less, is 20 m ² / g or less More preferable. The N ₂ SA of the hydroxide of Group 13 element in the present specification is a value measured by the BET method according to ASTM D3037-81.

From the viewpoint of dispersibility, the average particle diameter (d50) of hydroxides of Group 13 elements excluding aluminum hydroxide is preferably 0.1 μm or more, more preferably 0.2 μm or more. From the viewpoint of wear resistance, the average particle size of hydroxides of Group 13 elements other than aluminum hydroxide is preferably 10 μm or less, more preferably 8 μm or less. The average particle diameter (d50) of the hydroxide of Group 13 element in the present specification is a value calculated from the distribution of particle size (range and content).

By containing the coupling agent, a bond of polymer-coupling agent-hydroxide of Group 13 element can be constituted. Therefore, the first invention of the present invention deteriorates wear resistance and fuel economy by using three hydroxides of Group 13 elements other than aluminum hydroxide, silica and a silane coupling agent in combination. The grip performance can be improved without any. Examples of the coupling agent include silane coupling agents that bond with silica and polymers, carbon coupling agents that bond with carbon black and polymers, and the like.

The silane coupling agent can be bonded to silica and a polymer to improve the dispersibility of the silica and improve the fuel economy and abrasion resistance of the rubber composition. Further, as described above, the bond between the polymer, the coupling agent, and the hydroxide of the Group 13 element is generated, and the rubber composition can be supple and well extended, and has excellent grip performance.

As the silane coupling agent, any conventionally known one can be used as long as it can bond to the polymer and the hydroxide of the Group 13 element, for example, bis(3-triethoxysilylpropyl)tetrasulfide, Bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis( 3-trimethoxysilylpropyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3 -Sulfide system such as trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide; 3-mercapto Propyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and other mercapto-based compounds; vinyltriethoxysilane, vinyltrimethoxysilane, and other vinyl-based compounds; 3-amino Amino-based compounds such as propyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, and 3-(2-aminoethyl)aminopropyltrimethoxysilane; γ-glycidoxy Glycidoxy-based compounds such as propyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane and γ-glycidoxypropylmethyldimethoxysilane; 3-nitropropyltrimethoxysilane, 3- Nitro-based compounds such as nitropropyltriethoxysilane; chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane and 2-chloroethyltriethoxysilane Is mentioned. The above silane coupling agents may be used alone or in combination of two or more. Of these, sulfide-based silane coupling agents are preferable, and bis(3-triethoxysilylpropyl) tetrasulfide is more preferable, from the viewpoint of easy availability.

The content of the silane coupling agent with respect to 100 parts by mass of silica is 1 part by mass or more, preferably 4 parts by mass or more, and more preferably 9 parts by mass or more. When the content of the silane coupling agent is less than 1 part by mass, sufficient reinforcement effect and grip performance due to the inclusion of the silane coupling agent tend not to be obtained. The content of the silane coupling agent is 20 parts by mass or less, preferably 15 parts by mass or less. When the content of the silane coupling agent exceeds 20 parts by mass, the rubber composition tends to cure.

The carbon coupling agent can be combined with carbon black and a polymer to improve the dispersibility of the carbon black and improve the fuel economy and abrasion resistance of the rubber composition. Further, as described above, the bond between the polymer, the coupling agent, and the hydroxide of the Group 13 element is generated, and the rubber composition can be supple and well extended, and has excellent grip performance.

（化学式（２）中、ｎは１または２、ＭはＺｎ、Ｃｕ、Ｎａ、Ｃａのいずれかである。） Examples of carbon coupling agents include tetrasulfide compounds such as bis(dimethylaminoethyl)tetrasulfide (DME) and bis(dimethylaminopropyl)tetrasulfide (DMP); 1,2-bis(benzimidazolyl-2)ethane (EBZ ), 1,4′-bis(mercaptobenzimidazolyl-2)butane (C4SBZ) and other benzimidazole compounds; pyrithione metal salts and the like. Among them, a pyrithione metal salt is preferable, and a pyrithione metal salt represented by the following chemical formula (2) is more preferable because of easy availability.

(In the chemical formula (2), n is 1 or 2, and M is Zn, Cu, Na, or Ca.)

The pyrithione metal salt represented by the chemical formula (2) is zinc pyrithione, copper pyrithione, sodium pyrithione, and calcium pyrithione. Among them, zinc pyrithione is preferable from the viewpoint of easy availability. Pyrithione zinc is prepared by reacting 1-hydroxy-2-pyridinethione or a soluble salt thereof with a zinc salt (for example, ZnSO ₄ ) to precipitate pyrithione zinc as described in US Pat. No. 2,809,971. Is produced. Examples of commercially available zinc pyrithione include bis[1-hydroxy-2(1H)-pyridinethionate-O,S]zinc (ZPNO) manufactured by FLEXSYS.

The content of the carbon coupling agent with respect to 100 parts by mass of carbon black is 2 parts by mass or more, preferably 3 parts by mass or more, and more preferably 4 parts by mass or more. When the content of the carbon coupling agent is less than 2 parts by mass, the reinforcing effect becomes insufficient and the abrasion resistance tends to decrease. Further, the content of the carbon coupling agent is 20 parts by mass or less, preferably 18 parts by mass or less, and more preferably 15 parts by mass or less. When the content of the carbon coupling agent exceeds 20 parts by mass, the rubber composition tends to cure.

The rubber composition according to the first aspect of the present invention includes, in addition to the above components, compounding agents conventionally used in the rubber industry, for example, reinforcing agents such as carbon black and silica; fillers such as inorganic fillers; stearic acid. , Vulcanization activators such as zinc oxide; organic peroxides such as dicumyl peroxide and ditertiary butyl peroxide; processing aids; antiaging agents; waxes; vulcanizing agents such as sulfur; thiazole vulcanization acceleration Agents, thiuram-based vulcanization accelerators, sulfenamide-based vulcanization accelerators, guanidine-based vulcanization accelerators, and the like can be appropriately added.

It is preferable that the rubber composition according to the first invention contains carbon black, because the coloring effect can be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 100 m ² /g or more, more preferably 120 m ² /g or more. If it is less than 100 m ² /g, a sufficient reinforcing effect may not be obtained. Also, N ₂ SA of carbon black is preferably 250 meters ² / g or less, more preferably 300m ² / g. If it exceeds 250 m ² /g, the initial grip may be deteriorated. The nitrogen adsorption specific surface area of carbon black is determined by the method A of JIS K6217.

When carbon black is contained, its content is preferably 30 parts by mass or more, and more preferably 35 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 30 parts by mass, the grip-up effect due to sufficient elongation may not be obtained. The content of carbon black is preferably 100 parts by mass or less, more preferably 90 parts by mass or less. If it exceeds 100 parts by mass, the rolling resistance tends to deteriorate.

The rubber composition according to the first aspect of the invention preferably contains silica for the reason that good fuel economy is obtained and a reinforcing effect is obtained.

The nitrogen adsorption specific surface area of silica by the BET method is preferably 50 m ² /g or more, more preferably 100 m ² /g or more. If it is less than 50 m ² /g, the rubber strength tends to decrease. Further, the nitrogen adsorption specific surface area by the BET method of the silica is preferably 250 meters ² / g or less, more preferably 200m ² / g. If it exceeds 250 m ² /g, the workability tends to deteriorate. The nitrogen adsorption specific surface area of silica by the BET method can be measured by a method based on ASTM D3037-81.

The content of silica is preferably 0 parts by mass or more, and more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. Further, the content of silica 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. Within the above range, both grip and rolling resistance can be compatible.

As the antiaging agent, amine-based compounds, phenol-based compounds, imidazole-based compounds, carbamic acid metal salts and the like can be appropriately selected and used. Of these, amine compounds are preferable, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine is more preferable.

When the antioxidant is contained, the content thereof with respect to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and further preferably 1.2 parts by mass or more. The content of the antioxidant is preferably 8 parts by mass or less, more preferably 4 parts by mass or less, and further preferably 2.5 parts by mass or less.

As the wax, petroleum waxes such as paraffin wax and microcrystalline wax; non-petroleum waxes such as beeswax and candelilla wax, which are commonly used in the rubber industry, can be used. From the reason that ozone resistance can be improved, it is preferable to use a non-petroleum wax in combination with the antioxidant.

From the viewpoint of deterioration resistance, the content of the wax with respect to 100 parts by mass of the rubber component is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and further preferably 1.5 parts by mass or more. preferable. Further, the content of the wax is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and further preferably 6 parts by mass or less, for the reason that whitening is suppressed.

The method for producing the rubber composition according to the first invention is not particularly limited, and a known method can be used. For example, it can be produced by a method of kneading each of the above components using a rubber kneading device such as an open roll, a Banbury mixer, a closed kneader, and then vulcanizing.

The rubber composition according to the first invention is preferably used for a tread of a tire because it can improve grip performance without deteriorating wear resistance and fuel economy. Further, when the tread is a tread having a two-layer structure composed of a cap tread and a base tread, it can be used for both, but it is preferably used for the cap tread.

The tire of the first invention can be manufactured by a usual method using the rubber composition. That is, the rubber composition according to the first invention in which the above-mentioned respective components are blended as necessary is extruded in accordance with the shape of the tread of the tire in the unvulcanized stage, and the other tire is mounted on the tire molding machine. An unvulcanized tire is formed by bonding together the members and molding by a usual method. The tire of the first invention can be obtained by heating and pressurizing the unvulcanized tire in a vulcanizer.

Since the tire of the first invention can improve grip performance without deteriorating wear resistance and fuel economy, it is used as a tire for passenger cars, a tire for trucks/buses, a tire for motorcycles, a tire for competition, etc. Is more preferable, and it is more preferable to use it as a passenger car tire.

<Second invention>
A tire of the second invention is a rubber composition containing a hydroxide of a Group 13 element and a coupling agent with respect to a diene rubber component, and a reference rubber containing no hydroxide of a Group 13 element. It is characterized by comprising a tread composed of a rubber composition having a rubber hardness of -3 to +3 and an elongation at break of 103% or more with respect to the composition.

As the diene rubber component, the rubber component mentioned in the first invention can be used as in the first invention, and NR, ENR, SBR and BR are preferable.

As in the case of the silica or carbon black, which reacts with the coupling agent in the same manner as the hydroxide silica of the Group 13 element or carbon black, a polymer-coupling agent-hydroxide of the Group 13 element can be formed. Exhibits reinforcement. Group 13 element hydroxides have fewer reaction points and are easier to move than silica or carbon black, so rubber compositions containing Group 13 element hydroxides are supple and stretch well, and have good grip performance and steering stability. Excellent in Further, since it is not a conventional method for improving grip performance by increasing energy loss, there is no problem that fuel economy is deteriorated. Further, as mentioned above, the hydroxide of the 13th group element has the same reinforcing property as silica and carbon black, so that the grip performance is improved by adding a large particle size inorganic filler such as conventional calcium carbonate or magnesium oxide. The problem that the abrasion resistance becomes insufficient due to the above method does not occur. Therefore, it is possible to provide a rubber composition having improved grip performance without deteriorating wear resistance and fuel economy.

Examples of the hydroxide of Group 13 element include aluminum hydroxide, gallium hydroxide, indium hydroxide and thallium hydroxide. Among hydroxides of Group 13 elements, indium hydroxide is preferable because it has a large particle size.

From the viewpoint of wear resistance, the nitrogen adsorption specific surface area (N ₂ SA) of the hydroxide of Group 13 element is preferably 5 m ² /g or more, more preferably 10 m ² /g or more. Also, N ₂ SA of hydroxides of Group 13 elements, from the viewpoint of dispersibility, preferably less than 30 m ² / g, more preferably not more than ^{25m 2 / g, 20m 2 /} g or less is more preferred. The N ₂ SA of the hydroxide of Group 13 element in the present specification is a value measured by the BET method according to ASTM D3037-81.

From the viewpoint of dispersibility, the average particle diameter (d50) of the hydroxide of Group 13 element is preferably 0.1 μm or more, more preferably 0.2 μm or more. The average particle size of the hydroxide of Group 13 element is preferably 10 μm or less, more preferably 8 μm or less, from the viewpoint of wear resistance. The average particle diameter (d50) of the hydroxide of Group 13 element in the present specification is a value calculated from the distribution of particle size (range and content).

As the coupling agent, the silane coupling agent, the carbon coupling agent and the like mentioned in the first invention can be used in the same manner as in the first invention.

In the rubber composition according to the second invention, in addition to the above components, compounding agents conventionally used in the rubber industry, for example, reinforcing agents such as carbon black and silica; fillers such as inorganic fillers; stearic acid, zinc oxide. Vulcanization activators such as; Organic peroxides such as dicumyl peroxide, ditertiary butyl peroxide; Processing aids; Anti-aging agents; Waxes; Vulcanizing agents such as sulfur; Thiazole vulcanization accelerators, thiuram A vulcanization accelerator such as a system-based vulcanization accelerator, a sulfenamide-based vulcanization accelerator, a guanidine-based vulcanization accelerator, or the like can be appropriately blended as in the first invention.

The rubber composition according to the second invention is characterized in that the rubber hardness and the elongation at break compared to the reference rubber composition are predetermined values. By using a tire having a tread made of a rubber composition that satisfies the rubber hardness and the elongation at break, it is possible to obtain a tire having excellent grip performance without deteriorating wear resistance and fuel economy.

The reference rubber composition is a rubber composition obtained by the same composition and manufacturing method as the comparative rubber composition except that it does not contain a hydroxide of a Group 13 element.

The hardness of the rubber composition according to the second invention is -3 to +3 of the hardness of the reference rubber composition, and preferably -2 to +2. When the hardness is less than -3 of the standard rubber composition, steering stability may be deteriorated. Further, when the hardness exceeds +3 of the reference rubber composition, grip performance may be deteriorated. The rubber hardness in the present specification is a hardness measured by a type A durometer in an atmosphere of 25°C according to JIS K6253-3:2012.

The elongation at break according to the second invention is 103% or more, preferably 105% or more, of the elongation at break of the reference rubber composition. If the elongation at break is less than 103% of the standard rubber composition, the effect of improving the grip performance may not be obtained. The upper limit of elongation at break is not particularly limited. The elongation at break in this specification is the elongation at break measured at room temperature using a No. 3 dumbbell-shaped test piece in accordance with JIS K6251:2010.

The method for producing the rubber composition according to the second invention is not particularly limited, and a known method can be used. For example, it can be produced by a method of kneading each of the above components using a rubber kneading device such as an open roll, a Banbury mixer, a closed kneader, and then vulcanizing.

The rubber composition according to the second invention is preferably used for a tread of a tire because it can improve grip performance without deteriorating wear resistance and fuel economy. Further, when the tread is a tread having a two-layer structure composed of a cap tread and a base tread, it can be used for both, but it is preferably used for the cap tread.

The tire of the second invention can be manufactured by a usual method using the rubber composition. That is, the rubber composition according to the second invention in which the above-mentioned respective components are blended as necessary is extruded according to the shape of the tread of the tire in the unvulcanized stage, and the other tire is mounted on the tire molding machine. An unvulcanized tire is formed by bonding together the members and molding by a usual method. The tire of the first invention can be obtained by heating and pressurizing the unvulcanized tire in a vulcanizer.

Since the tire of the second invention can improve grip performance without deteriorating wear resistance and fuel economy, it is used as a tire for passenger cars, a tire for trucks/buses, a tire for motorcycles, a tire for competition, etc. Is more preferable, and it is more preferable to use it as a passenger car tire.

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

Hereinafter, various chemicals used in Examples and Comparative Examples will be summarized.
S-SBR: Tuffden 4350 manufactured by Asahi Kasei Co., Ltd. (Amount of bound styrene: 40% by mass, amount of vinyl bond: 38 mol%, containing 50 parts by weight of oil based on 100 parts by weight of rubber solid)
Modified SBR: HPR350 manufactured by JSR Corporation (modified S-SBR, amount of bound styrene: 21% by mass, amount of vinyl bond: 56 mol %, introduced into terminal by coupling with alkoxysilane, represented by chemical formula (1) Modification by compound (in the chemical formula (1), R ^{1 to} R ³ =methoxy group, R ⁴ and R ⁵ =hydrogen atom, m=3)
NR: RSS#3
BR: UBEPOL BR150B (high cis BR, cis 1,4 bond content: 97% by mass) manufactured by Ube Industries, Ltd.
Silica: Ultragill VN3 (N ₂ SA: 175 m ² /g) manufactured by Degussa
Carbon black: Diablack A manufactured by Mitsubishi Chemical Corporation (N110, N ₂ SA: 142 m ² /g, DBP: 116 ml/100 g)
Aluminum hydroxide: ATH#B manufactured by Sumitomo Chemical Co., Ltd. (average particle diameter: 0.6 μm, N ₂ SA: 15 m ² /g)
Indium hydroxide: manufactured by Showa Chemical Co., Ltd. (average particle size: 0.8 μm, N ₂ SA: 20 m ² /g)
Inorganic filler 1: Shiraishi Industry Co., Ltd. white luster flower CC (calcium carbonate, average particle diameter: 1 μm)
Inorganic filler 2: PUREMAG FNM-G (magnesium oxide, average particle diameter: 2 μm) manufactured by Tateho Chemical Industry Co., Ltd.
Oil: Diana Process Oil X140 manufactured by Japan Energy Co., Ltd.
Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Carbon coupling agent: zinc pyrithione manufactured by FLEXSYS (compound represented by chemical formula (2) (bis[1-hydroxy-2(1H)-pyridinethionate-O,S]zinc (ZPNO), in chemical formula (2)) , N=2, M=Zn)
Anti-aging agent: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Co., Ltd.
Wax: Sunnok N (petroleum wax) manufactured by Ouchi Shinko Chemical Co., Ltd.
Stearic acid: stearic acid "paulownia" manufactured by NOF CORPORATION
Zinc oxide: Two kinds of zinc oxide vulcanization accelerator manufactured by Mitsui Mining & Smelting Co., Ltd. 1: Nocceller D (DPG, 1,3-diphenylguanidine) manufactured by Ouchi Shinko Chemical Co., Ltd.
Vulcanization accelerator 2: Nocceller CZ (CZ, N-cyclohexyl-2-benzothiazole sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

Examples and Comparative Examples According to the formulation contents shown in Tables 1 and 2, using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd., materials other than sulfur and a vulcanization accelerator were discharged at a temperature of 150°C. The mixture was kneaded for 5.0 minutes to obtain a kneaded product. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded for 3.0 minutes at a discharge temperature of 100° C. to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press-vulcanized at 170° C. for 12 minutes with a mold having a thickness of 2 mm to obtain a sheet-shaped vulcanized rubber composition. Further, the unvulcanized rubber composition obtained is molded into a tread shape, and is bonded together with other tire members on a tire molding machine to form an unvulcanized tire, and press-vulcanized at 170° C. for 12 minutes, A test tire (size: 195/65R15) was manufactured. The following evaluation was performed on the obtained vulcanized rubber composition and test tire. In addition, Comparative Example 1 is a reference example of Examples 1 to 3 and Comparative Examples 2 and 3, Comparative Example 4 is a reference example of Examples 4 and 5, and Comparative Example 5, and Comparative Example 6 is a reference example of Examples 6 and 7. Reference example, Comparative example 8 is a reference example of Examples 7 and 8 and Comparative examples 9 and 10, Comparative example 11 is a reference example of Example 9 and Comparative examples 12 and 13, Comparative example 14 is Example 10 and Comparative example 15 And 16 reference examples.

<Rubber hardness>
According to JIS K6253-3:2012, the type A durometer hardness (rubber hardness) of the tire tread portion was measured in an atmosphere of 25°C.

<Elongation at break EB>
According to JIS K6251:2010, a tensile test is performed at room temperature using a No. 3 dumbbell-shaped test piece made of each vulcanized rubber composition, and the elongation at break EB (%) of each vulcanized rubber composition is measured. Then, the EB of each formulation was indexed by the following formula.
(EB index)=(EB of each formulation)/(EB of each reference example)×100

<Grip performance>
Each test tire having an internal pressure of 180 kPa was mounted on all wheels of a traction bus of T&T Co., Ltd., and a peak μ was measured immediately before the control system mounted on the test tire shaft locked the wheel at 65 km/h. .. The grip performance of each composition was expressed as an index by the following calculation formula. The larger the index, the larger the peak μ and the higher the grip performance.
(Grip performance index)=(peak μ of each formulation)/(peak μ of each reference example)×100

<Rolling resistance>
The loss tangent (tan δ) of each vulcanized rubber composition was measured under the conditions of a temperature of 70° C., an initial strain of 10%, and a dynamic strain of 2% using a viscoelasticity spectrometer VES manufactured by Iwamoto Seisakusho. The rolling resistance characteristic of each composition was expressed as an index by the following calculation formula. The larger the index, the better the rolling resistance characteristics (fuel economy).
(Rolling resistance index)=(tan δ of each reference example)/(tan δ of each compound)×100

<Abrasion resistance>
The wear amount of each vulcanized rubber composition was measured under the conditions of room temperature, a load of 1.0 kg and a slip ratio of 30% using a Lambourn abrasion tester manufactured by Iwamoto Seisakusho. The wear resistance of each composition was indexed by the following formula. The larger the index, the smaller the amount of wear and the better the wear resistance.
(Abrasion resistance index)=(Abrasion amount of each reference example)/(Abrasion amount of each compound)×100

From the results of Tables 1 and 2, it is understood that the tire of the first invention and the tire of the second invention are tires having excellent grip performance without deteriorating wear resistance and fuel economy.

Claims (7)

Diene rubber component, indium hydroxide and / or gallium hydroxide, and a tire with a tread composed of a rubber composition containing a coupling agent. The rubber composition is, relative to the reference rubber composition containing no indium hydroxide and / or gallium hydroxide, a rubber hardness -3 + 3, and elongation at break is of 103% or more, according to claim 1 Tires listed . Nitrogen adsorption specific surface area of indium hydroxide and/or gallium hydroxide (N ₂ SA) is 5m ² /G or more 30m ² The tire according to claim 1 or 2, which is less than /g. The tire according to any one of claims 1 to 3, wherein the indium hydroxide and/or gallium hydroxide has an average particle diameter (d50) of 0.1 to 10 µm. The tire according to any one of claims 1 to 4, wherein the rubber composition contains 5 parts by mass or more of indium hydroxide and/or gallium hydroxide with respect to 100 parts by mass of the diene rubber component. The rubber composition contains 10 parts by mass or more of silica with respect to 100 parts by mass of the diene rubber component, and contains 1 part by mass or more of a silane coupling agent with respect to 100 parts by mass of silica. The tire according to any one of 1. The tire according to any one of claims 1 to 6, wherein the diene rubber component contains a solution-polymerized styrene-butadiene rubber.