JP7293606B2 - Rubber composition and pneumatic tire - Google Patents

Description

The present invention relates to rubber compositions and pneumatic tires.

Conventionally, tires have been required to have various performances, and from the viewpoint of safety, grip performance is emphasized (see, for example, Patent Document 1).

JP 2014-009300 A

As a result of intensive studies by the present inventors, there is room for improvement in the prior art in terms of improving blowout resistance performance, grip performance, and grip stability performance in a well-balanced manner.
An object of the present invention is to solve the above problems and to provide a rubber composition and a pneumatic tire in which anti-blowout performance, grip performance, and grip stability performance are improved in a well-balanced manner.

The present invention comprises a rubber component, 0.5 to 5 parts by mass of a nitrogen compound having at least one nitrogen-containing cyclic structure per 100 parts by mass of the rubber component, and fine zinc oxide having an average primary particle size of 200 nm or less. and wherein A is the nitrogen compound content relative to 100 parts by mass of the rubber component, and B is the zinc oxide content relative to 100 parts by mass of the rubber component.
1.0 ≤ A/B ≤ 5.0 Formula (I)

The rubber composition preferably contains a phenolic compound.

The rubber composition preferably contains carbon black and/or white filler.

The rubber composition preferably contains an oil and/or a liquid diene polymer.

The nitrogen compound is preferably at least one compound selected from the group consisting of piperidine derivatives, imidazoles, and caprolactams.

The nitrogen compounds are preferably imidazoles.

The nitrogen compound is preferably 1,2-dimethylimidazole.

The phenolic compound is preferably at least one compound selected from the group consisting of alkylphenolic resins and phenolic antioxidants.

It is preferable to contain 80 parts by mass or more of carbon black with respect to 100 parts by mass of the rubber component.

The rubber composition is preferably a tread rubber composition.

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

Preferably, the tire member is a tread.

According to the present invention, a rubber component, 0.5 to 5 parts by mass of a nitrogen compound having at least one nitrogen-containing cyclic structure with respect to 100 parts by mass of the rubber component, and oxidized fine particles having an average primary particle diameter of 200 nm or less and zinc, and where A is the content of the nitrogen compound with respect to 100 parts by mass of the rubber component, and B is the content of zinc oxide with respect to 100 parts by mass of the rubber component, the rubber composition satisfies the above formula (I). , Blowout resistance performance, grip performance, and grip stability performance can be improved in a well-balanced manner.

The rubber composition comprises a rubber component, 0.5 to 5 parts by mass of a nitrogen compound having at least one nitrogen-containing cyclic structure per 100 parts by mass of the rubber component, and fine particles having an average primary particle diameter of 200 nm or less. zinc, and satisfies the above formula (I). As a result, blowout resistance performance, grip performance (especially dry grip performance), and grip stability performance can be improved in a well-balanced manner.

Although the reason why such effects are obtained is not necessarily clear, it is speculated as follows.
Blending the nitrogen compound into the rubber composition increases energy loss and improves grip performance. This effect can be obtained more preferably when the nitrogen compound is blended together with the phenolic compound.
On the other hand, as a result of studies by the present inventors, when the nitrogen compound is blended into the rubber composition, (1) the heat generation of the rubber during running is also increased, and there is a risk that blowout may occur due to the heat generation. (2) In addition, the rate of vulcanization is accelerated, and the proportion of monosulfide crosslinked chains in the crosslinked chains (hereinafter also referred to as monocrosslinking ratio) tends to decrease. , the grip performance tends to decrease during running, that is, the grip stability tends to decrease.
On the other hand, as a result of intensive studies by the present inventors, it was found that by blending fine zinc oxide, it is possible to prevent a decrease in the mono-crosslinking ratio after heat aging, and to improve blowout resistance and grip stability. turned out for the first time.
On the other hand, as mentioned above, the above nitrogen compound can increase heat build-up and grip power, but it may reduce blowout resistance and grip stability performance, so it was limited to blending in a specific amount. . By combining fine zinc oxide and a specific amount of the above nitrogen compound, it is possible to prevent a decrease in the mono-crosslinking ratio after heat aging. We have perfected a rubber that is less likely to deteriorate and less prone to blowouts.
Further, by satisfying the above formula (I) in the rubber composition containing fine zinc oxide particles and a specific amount of the nitrogen compound, the anti-blowout performance, the grip performance, and the grip stability performance are more suitably balanced. It is assumed that it can be improved.

The rubber composition satisfies the following formula (I).
1.0 ≤ A/B ≤ 5.0 Formula (I)
In formula (I), A is the content of the nitrogen compound (nitrogen compound having one or more cyclic structures containing nitrogen) per 100 parts by mass of the rubber component, and B is the amount of zinc oxide per 100 parts by mass of the rubber component. means content.
Here, the content of zinc oxide in B is the total content of zinc oxide in consideration of not only the content of fine zinc oxide particles having an average primary particle size of 200 nm or less, but also the content of zinc oxide other than the fine zinc oxide particles. means.
The lower limit is preferably 1.1 or more, more preferably 1.2 or more, even more preferably 1.3 or more, and particularly preferably 1.4 or more. The upper limit is preferably 4.5 or less, more preferably 4.0 or less, still more preferably 3.5 or less, particularly preferably 3.0 or less, most preferably 2.5 or less, and most preferably 2.0 or less. , and most preferably 1.8 or less. By setting the content within the above range, the above effects can be obtained more preferably.

The rubber composition contains a rubber component, and for example, a diene rubber can be used.
Diene rubbers include isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR). ) and the like. Examples of rubber components other than those mentioned above include butyl-based rubbers and fluororubbers. These may be used alone or in combination of two or more. As the rubber component, SBR, BR, and isoprene-based rubbers are preferable, and SBR is more preferable, because good grip performance can be obtained.

Here, the rubber component preferably has a weight average molecular weight (Mw) of 200,000 or more, more preferably 350,000 or more. Although the upper limit of Mw is not particularly limited, it is preferably 4,000,000 or less, more preferably 3,000,000 or less.
In the present specification, Mw and number average molecular weight (Mn) are measured by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: manufactured by Tosoh Corporation. TSKGEL SUPERMULTIPORE HZ-M) can be obtained by standard polystyrene conversion.

The rubber component may be non-modified diene rubber or modified diene rubber.
The modified diene rubber may be any diene rubber having a functional group that interacts with a filler such as silica. Terminal modified diene rubber modified with (terminal modified diene rubber having the above functional group at the end), main chain modified diene rubber having the above functional group on the main chain, and the above functional group on the main chain and terminal main chain end-modified diene rubber (for example, main chain end-modified diene rubber having the above functional group in the main chain and at least one end modified with the above modifier), or two or more in the molecule A terminal-modified diene rubber modified (coupled) with a polyfunctional compound having an epoxy group and introduced with a hydroxyl group or an epoxy group can be used.

Examples of the above functional groups include amino group, amido group, silyl group, alkoxysilyl group, isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, oxycarbonyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group and the like. . In addition, these functional groups may have a substituent. Among them, an amino group (preferably an amino group in which the hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), an alkoxysilyl group ( An alkoxysilyl group having 1 to 6 carbon atoms is preferred.

The SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. can be used. These may be used alone or in combination of two or more.

The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, particularly preferably 20% by mass or more, most preferably 25% by mass or more, and most preferably 30% by mass or more. It is at least 35% by mass, more preferably at least 35% by mass. Also, the styrene content is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less. Within the above range, the above effects can be obtained more favorably.
In this specification, the styrene content of SBR is calculated by H ¹ -NMR measurement.

As SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd., etc. can be used.

SBR may be unmodified SBR or modified SBR. Examples of modified SBR include modified SBR into which functional groups similar to those of modified diene rubber have been introduced.

When SBR is contained, the content of SBR in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and may be 100% by mass. By setting it within the above range, there is a tendency that the above effect can be obtained more preferably.

BR is not particularly limited, and for example, high cis BR having a high cis content, BR containing syndiotactic polybutadiene crystals, BR synthesized using a rare earth catalyst (rare earth BR), and the like can be used. These may be used alone or in combination of two or more. Among them, high-cis BR having a cis content of 90% by mass or more is preferable because it improves wear resistance performance.

BR may be non-denatured BR or denatured BR. Examples of modified BR include modified BR into which functional groups similar to those of modified diene rubber have been introduced.

As BR, for example, products of Ube Industries, Ltd., JSR Corporation, Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd., etc. can be used.

The isoprene rubber includes natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, and the like. As NR, for example, those commonly used in the tire industry, such as SIR20, RSS#3, and TSR20, can be used. The IR is not particularly limited, and for example IR2200 or the like commonly used in the tire industry can be used. Modified NR includes deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. Modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, and the like. These may be used alone or in combination of two or more.

The rubber composition contains a nitrogen compound having one or more nitrogen-containing cyclic structures.
The nitrogen compound is preferably at least one compound selected from the group consisting of piperidine derivatives, imidazoles, and caprolactams. The above nitrogen compounds may be used alone or in combination of two or more. Among them, imidazoles are more preferable.

Piperidine derivatives include, for example, 2,2,6,6-tetramethylpiperidine, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6- pentamethyl-4-piperidyl) sebacate, 1-[2-{3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy}ethyl]-4-{3-(3,5-di- t-butyl-4-hydroxyphenyl)propionyloxy}-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 8-acetyl-3-dodecyl- 7,7,9,9-tetramethyl-1,3,8-triazaspiro[4,5]decane-2,4-dione, poly[{6-(1,1,3,3-tetramethylbutyl)amino -1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4 -piperidyl)imino}], 1,2,2,6,6-tetramethyl-4-piperidyl-methacrylate, 2,2,6,6-tetramethyl-4-piperidyl-methacrylate, and the like. 6-tetramethylpiperidine and derivatives thereof, and the like. Among them, 2,2,6,6-tetramethylpiperidine or derivatives thereof are preferred, derivatives of 2,2,6,6-tetramethylpiperidine are more preferred, and bis(1,2,2,6,6-pentamethyl -4-piperidyl) sebacate is more preferred.

Examples of imidazoles include imidazole, 1-methylimidazole, 2-methylimidazole, N-acetylimidazole, 2-mercapto-1-methylimidazole, benzimidazole, 2-mercaptobenzimidazole, 2-phenylimidazole, 1-benzyl -2-methylimidazole, 1,2-dimethylimidazole and the like. Among them, 1,2-dimethylimidazole, 1-methylimidazole and 1-benzyl-2-methylimidazole are preferred.

Caprolactams include, for example, ε-caprolactam.

As the nitrogen compound, for example, products of Shikoku Kasei Co., Ltd., Sankyo Co., Ltd., etc. can be used.

The content of the nitrogen compound is 0.5 parts by mass or more, preferably 1 part by mass or more, and more preferably 2 parts by mass or more with respect to 100 parts by mass of the rubber component. The content of the nitrogen compound is 5 parts by mass or less, more preferably 4.5 parts by mass or less, and even more preferably 4 parts by mass or less. By setting the content within the above range, the above effects can be obtained more preferably.

The rubber composition preferably contains a phenolic compound together with the nitrogen compound. As a result, the above effects (in particular, the effect of improving grip performance) can be obtained more favorably.
The phenolic compound is preferably at least one compound selected from the group consisting of alkylphenolic resins and phenolic antioxidants. The above phenolic compounds may be used alone or in combination of two or more. Among them, the phenol-based anti-aging agent is more preferable because it increases the energy loss in the temperature range in which the tire is used.

Examples of alkylphenol-based resins include alkylphenol-aldehyde condensed resins obtained by reacting alkylphenol with aldehydes such as formaldehyde, acetaldehyde, and furfural with an acid or alkali catalyst; Alkylphenol alkyne condensed resins obtained; Modified alkylphenol resins obtained by modifying these resins with compounds such as cashew oil, tall oil, linseed oil, various animal and vegetable oils, unsaturated fatty acids, rosin, alkylbenzene resins, aniline, melamine; is mentioned. Among them, alkylphenol alkyne condensation resins are preferred, and alkylphenol acetylene condensation resins are particularly preferred.

Examples of alkylphenols constituting the alkylphenol-based resin include cresol, xylenol, t-butylphenol, octylphenol, nonylphenol and the like. Among them, phenols having a branched alkyl group such as t-butylphenol are preferred, and t-butylphenol is particularly preferred.

The softening point of the alkylphenol resin is preferably 60 to 200°C. The upper limit is more preferably 160° C. or lower, more preferably 150° C. or lower, and the lower limit is more preferably 100° C. or higher, even more preferably 130° C. or higher. By setting the content within the above range, the above effects can be obtained more preferably.
In this specification, the softening point is the temperature at which the sphere descends when the softening point specified in JIS K 6220-1:2001 is measured with a ring and ball type softening point measuring device.

As the alkylphenol-based resin, for example, products of BASF Corporation can be used.

Examples of phenol-based anti-aging agents include mono-phenol-based anti-aging agents, bisphenol-based anti-aging agents, and polyphenol-based anti-aging agents.
Monophenol anti-aging agents include, for example, 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butylphenol , 1-oxy-3-methyl-4-isopropylbenzene, butylhydroxyanisole, 2,4-dimethyl-6-tert-butylphenol, n-octadecyl-3-(4′-hydroxy-3′,5′-di- tert-butylphenyl)propionate, styrenated phenol, and the like.
Examples of bisphenol anti-aging agents and polyphenol anti-aging agents include 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis-(4-ethyl -6-tert-butylphenol), 4,4′-butylidene-bis-(3-methyl-6-tert-butylphenol), 1,1′-bis-(4-hydroxyphenyl)-cyclohexane, tetrakis-[methylene- 3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propionate]methane and the like.
Among them, bisphenol-based anti-aging agents are preferable, and 4,4′-butylidene-bis-(3-methyl-6-tert-butylphenol) is more preferable, because the above effects can be obtained more preferably.

As the phenol-based antioxidant, for example, products of Ouchi Shinko Kagaku Co., Ltd., Sumitomo Chemical Co., Ltd., etc. can be used.

When a phenolic compound is contained, the content of the phenolic compound is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and still more preferably 2 parts by mass or more, relative to 100 parts by mass of the rubber component. Particularly preferably, it is 3 parts by mass or more. The content of the phenolic compound is preferably 80 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 25 parts by mass or less, particularly preferably 20 parts by mass or less, and most preferably 15 parts by mass or less. By setting the content within the above range, the above effects can be obtained more preferably.

The mass ratio of the contents of the nitrogen compound and the phenolic compound (content of the nitrogen compound/content of the phenolic compound) is preferably 0.05 or more, more preferably 0.10 or more, further preferably 0.10 or more. It is 15 or more, preferably 2.0 or less, more preferably 1.2 or less, still more preferably 1.0 or less, and particularly preferably 0.8 or less. By setting the content within the above range, the above effects can be obtained more preferably.

The rubber composition contains fine zinc oxide particles having an average primary particle size of 200 nm or less.

The average primary particle size of the zinc oxide particles is 200 nm or less, preferably 150 nm or less, more preferably 120 nm or less, and even more preferably 100 nm or less. The average primary particle size of fine zinc oxide is preferably 20 nm or more, more preferably 30 nm or more. By setting the content within the above range, the above effects can be obtained more preferably.

In the present specification, the average primary particle size of zinc oxide is the primary particle size when the BET specific surface area measured by the BET method is converted into a true spherical particle model.
Here, the primary particle diameter when converted from the BET specific surface area to the true spherical particle model can be calculated by the following relational expression. If a primary particle is regarded as an ideal sphere, the relationship represented by the following formula holds between the surface area (S), volume (V), density (ρ) and specific surface area (SSA) of one particle. do.
SSA=1/(V・ρ)×S
Here, since V and S are physical quantities uniquely determined by the particle size, the particle size can be obtained from the specific surface area and density. Density can be conveniently determined by, for example, a commercially available pycnometer.

The content of fine zinc oxide is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, still more preferably 0.7 parts by mass or more, and particularly preferably 1 part by mass, based on 100 parts by mass of the rubber component. Part by mass or more. Also, the content of fine zinc oxide particles is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, even more preferably 4 parts by mass or less, and particularly preferably 3 parts by mass or less. By setting the content within the above range, the above effects can be obtained more preferably.

The rubber composition may contain zinc oxide other than the fine zinc oxide particles. When zinc oxide other than the fine zinc oxide is blended, the total content of zinc oxide may be the same content as in the case of using fine zinc oxide alone.

As zinc oxide, for example, products of Mitsui Kinzoku Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

The rubber composition contains carbon black and/or white filler as a filler (reinforcing filler). Among them, it is preferable to contain carbon black from the viewpoint that the above effects can be obtained more satisfactorily.

Examples of carbon black include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550 and N762. These may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 80 m ² /g or more, more preferably 120 m ² /g or more, still more preferably 130 m ² /g or more. Also, the N ₂ SA is preferably 200 m ² /g or less, more preferably 170 m ² /g or less, still more preferably 155 m ² /g or less. By setting the content within the above range, the above effects can be obtained more preferably.
The nitrogen adsorption specific surface area of carbon black is determined according to JIS K6217-2:2001.

The dibutyl phthalate oil absorption (DBP) of carbon black is preferably 50 ml/100 g or more, more preferably 100 ml/100 g or more. Also, the DBP is preferably 200 ml/100 g or less, more preferably 150 ml/100 g or less. By setting the content within the above range, the above effects can be obtained more preferably.
The DBP of carbon black can be measured according to JIS-K6217-4:2001.

As carbon black, for example, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Shin Nikka Carbon Co., Ltd., Columbia Carbon Co., Ltd. can be used.

When carbon black is contained, the content of carbon black with respect to 100 parts by mass of the rubber component is preferably 30 parts by mass or more, more preferably 60 parts by mass or more, still more preferably 80 parts by mass or more, and particularly preferably 90 parts by mass or more. is. The content is preferably 300 parts by mass or less, more preferably 250 parts by mass or less, still more preferably 200 parts by mass or less, particularly preferably 150 parts by mass or less, and most preferably 120 parts by mass or less. By setting the content within the above range, the above effects can be obtained more preferably.

White fillers include those commonly used in the rubber industry, such as silica, calcium carbonate, mica such as sericite, aluminum hydroxide, magnesium oxide, magnesium hydroxide, clay, talc, alumina, titanium oxide. etc. can be used, and from the viewpoint of fuel efficiency, silica is preferred. These may be used alone or in combination of two or more.

Silica is not particularly limited, and examples thereof include dry silica (anhydrous silicic acid) and wet silica (hydrous silicic acid). These may be used alone or in combination of two or more. Among them, wet-process silica is preferable because it has many silanol groups.

As silica, for example, products of Degussa, Rhodia, Tosoh Silica, Solvay Japan, Tokuyama, etc. can be used.

The N ₂ SA of the white filler is preferably 50 m ² /g or more, more preferably 150 m ² /g or more. Also, the N ₂ SA is preferably 300 m ² /g or less, more preferably 200 m ² /g or less.
The N ₂ SA of the white filler can be measured according to ASTM D3037-81.

When a white filler is contained, the content of the white filler (silica) with respect to 100 parts by mass of the rubber component is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, and still more preferably 50 parts by mass or more. The content is preferably 200 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 80 parts by mass or less.

In the rubber composition, the content of carbon black in 100% by mass of the filler (reinforcing filler) is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably, from the viewpoint of the performance balance. is 95% by mass or more. The upper limit is not particularly limited, and may be 100% by mass.

When the rubber composition contains a white filler, it preferably contains a silane coupling agent together with the white filler.
The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, Bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis ( 3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) ) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3- sulfides such as triethoxysilylpropyl methacrylate monosulfide; 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; vinyl-based such as methoxysilane; amino-based such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These may be used alone or in combination of two or more.

Examples of silane coupling agents that can be used include products of Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azmax Co., Ltd., Dow Corning Toray Co., Ltd., and the like.

When a silane coupling agent is contained, the content of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 2 parts by mass or more, and still more preferably 3 parts by mass or more with respect to 100 parts by mass of silica. is. Also, the content is preferably 20 parts by mass or less, more preferably 16 parts by mass or less, and even more preferably 12 parts by mass or less.

The rubber composition may contain a plasticizer. The plasticizer is not particularly limited, but examples thereof include oils, liquid polymers (liquid diene-based polymers), and liquid resins. One type of these plasticizers may be used, or two or more types may be used in combination.

Among the plasticizers, at least one selected from the group consisting of oils, liquid polymers, and liquid resins is preferable. ) is more preferred, and oil is even more preferred.

From the environmental point of view, the plasticizer preferably has a polycyclic aromatic content (PCA) of less than 3% by mass, more preferably less than 1% by mass. The polycyclic aromatic content (PCA) is measured according to the British Petroleum Institute method 346/92.

The above oils are not particularly limited, and process oils such as paraffinic process oils, aromatic process oils, and naphthenic process oils, low PCA (polycyclic aromatic) process oils such as TDAE and MES, vegetable oils and fats, and Conventionally known oils such as mixtures thereof can be used. Among them, aromatic process oils are preferred. Specific examples of the aromatic process oil include the Diana process oil AH series manufactured by Idemitsu Kosan Co., Ltd., and the like.

As oil, for example, Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H&R, Toyokuni Oil Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd. etc. products can be used.

The liquid polymer (liquid diene-based polymer) is a diene-based polymer that is liquid at room temperature (25° C.).
The liquid diene-based polymer preferably has a polystyrene-equivalent weight-average molecular weight (Mw) measured by gel permeation chromatography (GPC) of 1.0×10 ³ or more, preferably 3.0×10 ³ or more. more preferably 2.0×10 ⁵ or less, and more preferably 1.5×10 ⁴ or less.
In addition, in this specification, Mw of a liquid diene polymer is a polystyrene conversion value measured by gel permeation chromatography (GPC).

Liquid diene-based polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), and the like. be done.

Examples of the liquid resin include, but are not particularly limited to, liquid aromatic vinyl polymers, coumarone-indene resins, indene resins, terpene resins, rosin resins, and hydrogenated products thereof.

A liquid aromatic vinyl polymer is a resin obtained by polymerizing α-methylstyrene and/or styrene. Examples include liquid resins such as copolymers.

A liquid coumarone-indene resin is a resin containing coumarone and indene as main monomer components constituting the skeleton (main chain) of the resin. , styrene, α-methylstyrene, methylindene, and vinyltoluene.

A liquid indene resin is a liquid resin containing indene as a main monomer component that constitutes the skeleton (main chain) of the resin.

Liquid terpene resins are resins obtained by polymerizing terpene compounds such as α-pinene, β-pinene, camphor, and dipetene, and liquids represented by terpene phenol, which is a resin obtained from a terpene compound and a phenolic compound as raw materials. It is a terpene resin.

The liquid rosin resin is a liquid rosin resin represented by natural rosin, polymerized rosin, modified rosin, ester compounds thereof, or hydrogenated products thereof.

When a plasticizer is contained, the content of the plasticizer (preferably oil) is preferably 30 parts by mass or more, more preferably 60 parts by mass or more, and still more preferably 80 parts by mass or more with respect to 100 parts by mass of the rubber component. , particularly preferably 100 parts by mass or more, most preferably 120 parts by mass or more. Also, the content is preferably 300 parts by mass or less, more preferably 250 parts by mass or less, even more preferably 200 parts by mass or less, and particularly preferably 180 parts by mass or less. By setting the content within the above range, the above effects can be obtained more preferably.
The plasticizer content also includes the amount of oil contained in the rubber (oil-extended rubber).

A solid resin (a polymer that is in a solid state at room temperature (25° C.)) may be blended with the rubber composition.

The solid resin is not particularly limited, but for example, solid styrene-based resin, coumarone-indene resin, terpene-based resin, pt-butylphenolacetylene resin, acrylic resin, dicyclopentadiene-based resin (DCPD-based resin). , C5 petroleum resin, C9 petroleum resin, C5C9 petroleum resin, and the like. These may be used alone or in combination of two or more.

The solid styrenic resin is a solid polymer using a styrenic monomer as a constituent monomer, and examples thereof include polymers polymerized with a styrenic monomer as a main component (50% by mass or more). Specifically, styrene monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-Chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.), homopolymers obtained by polymerizing each alone, copolymers obtained by copolymerizing two or more styrene monomers, and styrene monomers and copolymers of other monomers copolymerizable therewith.

Examples of the other monomers include acrylonitrile and methacrylonitrile, acrylics, unsaturated carboxylic acids such as methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, chloroprene, and butadiene. dienes such as isoprene; olefins such as 1-butene and 1-pentene; α,β-unsaturated carboxylic acids such as maleic anhydride and acid anhydrides thereof;

Among them, solid α-methylstyrene resins (α-methylstyrene homopolymers, copolymers of α-methylstyrene and styrene, etc.) are preferred.

Examples of the solid coumarone-indene resin include solid resins having the same structural units as those of the liquid coumarone-indene resin described above.

Solid terpene-based resins include polyterpene, terpenephenol, and aromatic modified terpene resins.
Polyterpenes are resins obtained by polymerizing terpene compounds and hydrogenated products thereof. Terpene compounds are hydrocarbons represented by the composition (C ₅ H ₈ ) _n and their oxygen-containing derivatives, such as monoterpene (C ₁₀ H ₁₆ ), sesquiterpene (C ₁₅ H ₂₄ ), diterpene (C ₂₀ H ₃₂ ) and the like, which are compounds having a terpene as a basic skeleton, such as α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene , 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol and the like.

As the solid polyterpene, terpene resin such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, β-pinene/limonene resin made from the above-mentioned terpene compound as a raw material, and hydrogenation of the terpene resin Also included are solid resins such as treated hydrogenated terpene resins.

Examples of the solid terpene phenol include a solid resin obtained by copolymerizing the terpene compound and a phenolic compound, and a solid resin obtained by hydrogenating the resin. Specifically, the terpene compound, the phenolic compound and A solid resin obtained by condensing formalin can be mentioned. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol.

Examples of solid aromatic-modified terpene resins include solid resins obtained by modifying terpene resins with aromatic compounds, and solid resins obtained by hydrogenating the resins. The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring. Examples include phenol compounds such as phenol, alkylphenol, alkoxyphenol, unsaturated hydrocarbon group-containing phenol; naphthol compounds such as unsaturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, unsaturated hydrocarbon group-containing styrene; coumarone, indene, and the like.

Examples of solid pt-butylphenol acetylene resins include solid resins obtained by condensation reaction of pt-butylphenol and acetylene.

Although the solid acrylic resin is not particularly limited, a solvent-free acrylic solid resin can be preferably used because it contains few impurities and provides a resin with a sharp molecular weight distribution.

A solid solvent-free acrylic resin is produced by a high-temperature continuous polymerization method (high-temperature continuous bulk polymerization method) (U.S. Pat. No. 4,414) without using polymerization initiators, chain transfer agents, organic solvents, etc. , 370, JP-A-59-6207, JP-B-5-58005, JP-A-1-313522, US Pat. (meth)acrylic resins (polymers) synthesized by the method described in No. pp. 42-45, etc.). In addition, in this specification, (meth)acryl means methacryl and acryl.

The solid acrylic resin preferably does not substantially contain auxiliary materials such as a polymerization initiator, a chain transfer agent, and an organic solvent. Further, the acrylic resin preferably has a relatively narrow composition distribution and molecular weight distribution obtained by continuous polymerization.

As described above, the solid acrylic resin preferably does not substantially contain auxiliary materials such as a polymerization initiator, a chain transfer agent, an organic solvent, etc., that is, has a high purity. The purity of the solid acrylic resin (percentage of resin contained in the resin) is preferably 95% by mass or more, more preferably 97% by mass or more.

Examples of monomer components constituting solid acrylic resins include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth) Examples include (meth)acrylic acid derivatives such as acrylamide derivatives.

In addition to (meth)acrylic acid and (meth)acrylic acid derivatives, styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinyl are also used as monomer components constituting solid acrylic resins. Aromatic vinyls such as naphthalene may also be used.

The solid acrylic resin may be a resin composed only of a (meth)acrylic component, or a resin containing components other than the (meth)acrylic component as constituent elements.
Moreover, the solid acrylic resin may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

Plasticizers and solid resins, for example, Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF Corporation, Arizona Chemical Co., Nichinuri Chemical Co., Ltd. , Nippon Shokubai Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., etc. can be used.

When a solid resin is contained, the content thereof is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and still more preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. Also, the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. Within the above range, there is a tendency for better grip performance to be obtained.

The rubber composition preferably contains stearic acid.
Conventionally known stearic acid can be used, for example, products of NOF Corporation, NOF, Kao Corporation, Fuji Film Wako Pure Chemical Industries, Ltd., Chiba Fatty Acids Co., Ltd. can be used.

When stearic acid is contained, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, relative to 100 parts by mass of the rubber component. The above content is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, and even more preferably 2.5 parts by mass or less. Within the above numerical range, good grip performance tends to be obtained.

The rubber composition may contain an anti-aging agent other than the phenol-based anti-aging agent.
Examples of anti-aging agents other than phenol-based anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; Diphenylamine antioxidant; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-di-2- p-phenylenediamine antioxidants such as naphthyl-p-phenylenediamine; and quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline. These may be used alone or in combination of two or more. Among them, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferable, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, 2,2,4-trimethyl-1 , 2-dihydroquinoline polymers are more preferred.

As the anti-aging agent, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Kagaku Kogyo Co., Ltd., Flexis, etc. can be used, for example.

When an anti-aging agent other than a phenol-based anti-aging agent is contained, the content of the anti-aging agent other than the phenol-based anti-aging agent is preferably 0.5 parts by mass or more, more preferably 100 parts by mass of the rubber component. is 0.7 parts by mass or more. Moreover, the content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less.

The rubber composition preferably contains wax.
The wax is not particularly limited, and includes petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant waxes and animal waxes; synthetic waxes such as polymers of ethylene and propylene. These may be used alone or in combination of two or more.

As the wax, for example, products of Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., Seiko Kagaku Co., Ltd., etc. can be used.

When wax is contained, the wax content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component. Moreover, the content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less.

The rubber composition preferably contains sulfur.
Sulfur includes powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur and the like commonly used in the rubber industry. These may be used alone or in combination of two or more.

As sulfur, for example, products of Tsurumi Chemical Industry Co., Ltd., Karuizawa Io Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis Co., Ltd., Nippon Kantan Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

When sulfur is contained, the content of sulfur is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the rubber component. Moreover, the content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less. Within the above numerical range, the above effects tend to be obtained favorably.

The rubber composition preferably contains a vulcanization accelerator.
Vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide (TMTD ), tetrabenzyl thiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N) and other thiuram vulcanization accelerators; N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl- 2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N,N'-diisopropyl-2-benzothiazolesulfenamide, etc. and guanidine-based vulcanization accelerators such as diphenylguanidine, diorthotolylguanidine and orthotolylbiguanidine. These may be used alone or in combination of two or more. Among them, thiuram-based vulcanization accelerators and thiazole-based vulcanization accelerators are preferable, and it is more preferable to use thiuram-based vulcanization accelerators and thiazole-based vulcanization accelerators in combination.

As the vulcanization accelerator, for example, products manufactured by Kawaguchi Kagaku Co., Ltd., Ouchi Shinko Kagaku Co., etc. can be used.

When a vulcanization accelerator is contained, the content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and still more preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. be. Also, the content is preferably 15 parts by mass or less, more preferably 10 parts by mass or less. Within the above numerical range, the above effects tend to be obtained favorably.

In addition to the above components, the rubber composition may contain additives commonly used in the tire industry, vulcanizing agents other than sulfur (e.g., organic cross-linking agents, organic peroxides); etc. can be exemplified. The content of each of these components is preferably 0.1 parts by mass or more and preferably 200 parts by mass or less with respect to 100 parts by mass of the rubber component.

The rubber composition can be produced, for example, by kneading the above components using a rubber kneading device such as an open roll mixer or a Banbury mixer, followed by vulcanization.

As for the kneading conditions, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C in the base kneading step for kneading additives other than the cross-linking agent (vulcanizing agent) and the vulcanization accelerator. In the finishing kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 120°C or lower, preferably 80 to 110°C. A composition obtained by kneading a vulcanizing agent and a vulcanization accelerator is usually subjected to vulcanization treatment such as press vulcanization. The vulcanization temperature is generally 140-190°C, preferably 150-185°C.

Examples of the rubber composition include tread (cap tread), sidewall, base tread, undertread, clinch, bead apex, breaker cushion rubber, carcass cord covering rubber, insulation, chafer, inner liner, etc. It can be used for tire members such as side reinforcing layers of run-flat tires (as a rubber composition for tires). Among others, it is preferably used for treads.

The pneumatic tire of the present invention is manufactured by a normal method using the rubber composition. That is, a rubber composition blended with various additives as necessary is extruded in the unvulcanized stage according to the shape of each tire member (especially the tread (cap tread)), and is placed on a tire building machine. After forming an unvulcanized tire by molding by a normal method with other tire members and bonding together with other tire members to form an unvulcanized tire, the tire can be manufactured by heating and pressurizing in a vulcanizer.

The above pneumatic tires include passenger car tires, large passenger car tires, large SUV tires, truck and bus tires, motorcycle tires, competition tires, studless tires (winter tires), runflat tires, aircraft tires, and mining tires. It is preferably used as a racing tire and the like, and is particularly preferably used as a competition tire.

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

窒素化合物３：四国化成（株）製の１Ｂ２ＭＺ（１－ベンジル－２－メチルイミダゾール）
フェノール系老化防止剤：大内新興化学（株）製のノクラック ＮＳ－３０（４，４’－ブチリデン－ビス－（３－メチル－６－ｔｅｒｔ－ブチルフェノール））
アルキルフェノール系樹脂：ＢＡＳＦ社製のコレシン（ｐ－ｔ－ブチルフェノールアセチレン樹脂（ｐ－ｔ－ブチルフェノールとアセチレンの縮合樹脂）、軟化点１４５℃、Ｔｇ９８℃）
老化防止剤：住友化学（株）製のアンチゲン６Ｃ（Ｎ－（１，３－ジメチルブチル）－Ｎ’－フェニル－ｐ－フェニレンジアミン）
ワックス：大内新興化学（株）製のサンノックＮ
ステアリン酸：日油（株）製のステアリン酸「椿」
酸化亜鉛：三井金属工業（株）製の酸化亜鉛２種（平均一次粒子径：４００ｎｍ）
微粒子酸化亜鉛：ハクスイテック（株）製のジンコックスーパーＦ－２（平均一次粒子径：６５ｎｍ）
硫黄：軽井沢硫黄（株）製の粉末硫黄
加硫促進剤ＤＭ：大内新興化学工業（株）製のノクセラーＤＭ（ジ－２－ベンゾチアゾリルジスルフィド）
加硫促進剤ＴＯＴ：大内新興化学工業（株）製のノクセラーＴＯＴ－Ｎ（テトラキス（２－エチルヘキシル）チウラムジスルフィド） Various chemicals used in Examples and Comparative Examples are collectively described below.
SBR: Tafden 4850 manufactured by Asahi Kasei Corporation (S-SBR, oil-extended [containing 50 parts by mass of oil per 100 parts by mass of rubber solids], styrene content: 40% by mass)
Carbon black: SEAST 9 SAF (N ₂ SA: 142 m ² /g, DBP: 115 ml/100 g) manufactured by Tokai Carbon Co., Ltd.
Oil: H&R aromatic process oil (TDAE oil, Vivatec 500)
Nitrogen compound 1: 1,2-DMZ (1,2-dimethylimidazole) manufactured by Shikoku Kasei Co., Ltd.
Nitrogen compound 2: Sanol LS-765 (bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (compound represented by the following formula)) manufactured by Sankyo Co., Ltd.

Nitrogen compound 3: 1B2MZ (1-benzyl-2-methylimidazole) manufactured by Shikoku Kasei Co., Ltd.
Phenolic anti-aging agent: Nocrack NS-30 (4,4'-butylidene-bis-(3-methyl-6-tert-butylphenol)) manufactured by Ouchi Shinko Chemical Co., Ltd.
Alkylphenol-based resin: Colesin manufactured by BASF (pt-butylphenol acetylene resin (condensation resin of pt-butylphenol and acetylene), softening point 145°C, Tg 98°C)
Antiaging agent: Antigen 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Wax: Sannok N manufactured by Ouchi Shinko Chemical Co., Ltd.
Stearic acid: stearic acid "Tsubaki" manufactured by NOF Corporation
Zinc oxide: Two kinds of zinc oxide manufactured by Mitsui Kinzoku Kogyo Co., Ltd. (average primary particle size: 400 nm)
Fine zinc oxide: Jincoq Super F-2 manufactured by Hakusui Tech Co., Ltd. (average primary particle size: 65 nm)
Sulfur: powdered sulfur vulcanization accelerator DM manufactured by Karuizawa Sulfur Co., Ltd.: Nocceler DM (di-2-benzothiazolyl disulfide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Vulcanization accelerator TOT: Noxceler TOT-N (tetrakis (2-ethylhexyl) thiuram disulfide) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

[Examples and Comparative Examples]
According to the formulation shown in Table 1, chemicals other than sulfur and vulcanization accelerator were kneaded at 165° C. for 4 minutes using a Banbury mixer to obtain a kneaded product. Next, using an open roll, sulfur and a vulcanization accelerator were added to the resulting kneaded material and kneaded at 80° C. for 4 minutes to obtain an unvulcanized rubber composition. Further, the obtained unvulcanized rubber composition was press vulcanized at 170° C. for 20 minutes to obtain a vulcanized rubber composition.

Further, the obtained unvulcanized rubber composition is extruded into a cap tread shape, laminated together with other tire members on a tire building machine to form an unvulcanized tire, and heated at 150° C. for 20 minutes. It was press-vulcanized to obtain a test tire (tire size: 195/65R15).

The vulcanized rubber compositions and test tires thus obtained were used for the following evaluations. Table 1 shows the results. In addition, in Table 1, Comparative Example 1 was used as a reference comparative example.

<Blowout resistance>
The obtained vulcanized rubber composition was subjected to repeated compressive deformation using a flexometer (manufactured by Leo Labo Co., Ltd.), and the time until blowout occurred due to self-heating of the rubber was measured. The test conditions are as follows. The results were indexed using the blowout time of the rubber composition of Comparative Example 1 as 100. The larger the index value, the better the blowout time and the better the anti-blowout performance. A score of 97 or higher was judged to be good.
Test conditions: Repeated compressive strain 20% Frequency 10Hz

<Dry grip performance>
Test tires were mounted on all wheels of a domestically produced FR vehicle (2000 cc engine displacement), and the actual vehicle was run for 15 laps on a 3 km dry asphalt test course. A test driver evaluated the control at the time of the best lap at that time, and indexed with Comparative Example 1 being 100. A larger value indicates better grip performance on a dry road surface.

<Grip stability performance>
Test tires were mounted on all wheels of a domestically produced FR vehicle (2000 cc engine displacement), and the actual vehicle was run for 15 laps on a 3 km dry asphalt test course. Grip stability was defined as the difference between the best time and the average lap time of the 10th to 15th laps in the second half.
The value of Comparative Example 1 is indexed as 100, and the larger the value, the better the grip stability performance.

From Table 1, a rubber component, 0.5 to 5 parts by mass of a nitrogen compound having at least one nitrogen-containing cyclic structure per 100 parts by mass of the rubber component, and fine zinc oxide having an average primary particle diameter of 200 nm or less. wherein A is the content of the nitrogen compound with respect to 100 parts by mass of the rubber component, and B is the content of zinc oxide with respect to 100 parts by mass of the rubber component. , Grip performance and grip stability performance were improved in a well-balanced manner.

By comparing Comparative Examples 1, 2, 4, and Example 1, it was found that the combined use of the nitrogen compound and fine zinc oxide particles synergistically improved blowout resistance and grip performance.

Claims (11)

a rubber component comprising a styrene-butadiene rubber ;
0.5 to 5 parts by mass of a nitrogen compound having one or more nitrogen-containing cyclic structures with respect to 100 parts by mass of the rubber component;
and fine zinc oxide with an average primary particle size of 200 nm or less,
When the content of the nitrogen compound with respect to 100 parts by mass of the rubber component is A, and the content of zinc oxide with respect to 100 parts by mass of the rubber component is B, the following formula (I) is satisfied,
The rubber composition, wherein the nitrogen compound is at least one compound selected from the group consisting of piperidine derivatives and imidazoles.
1.1 ≤ A/B ≤ 5.0 Formula (I) The rubber composition according to Claim 1, which contains a phenolic compound. 3. The rubber composition according to claim 1, which contains carbon black and/or white filler. The rubber composition according to any one of claims 1 to 3, comprising an oil and/or a liquid diene polymer. The rubber composition according to any one of claims 1 to 4, wherein the nitrogen compound is an imidazole. The rubber composition according to any one of claims 1 to 4, wherein the nitrogen compound is 1,2-dimethylimidazole. 3. The rubber composition according to claim 2, wherein said phenolic compound is at least one compound selected from the group consisting of alkylphenolic resins and phenolic antioxidants. The rubber composition according to any one of claims 1 to 7, which contains 80 parts by mass or more of carbon black with respect to 100 parts by mass of the rubber component. The rubber composition according to any one of claims 1 to 8, which is a rubber composition for treads. A pneumatic tire comprising a tire member using the rubber composition according to any one of claims 1 to 8. A pneumatic tire according to claim 10, wherein said tire component is a tread.