JP6496102B2 - tire - Google Patents

Description

  The present invention relates to a tire including a base tread composed of a predetermined rubber composition.

  In recent years, there has been an increasing demand for low fuel consumption for automobiles, and it is known that the rubber physical properties of tires have an important effect on low fuel consumption. Therefore, it is desired to provide a rubber composition for tires with excellent fuel efficiency. ing. In order to obtain a fuel-efficient tire, for example, the tread portion has a two-layer structure (a cap tread that is a surface layer of the tread and a base tread that is an inner surface layer), and a rubber composition that is excellent in low heat generation is used for the base tread. Although the method to use is known, in recent years, the demand for lower fuel consumption has become stronger and more excellent low heat generation properties have been demanded. In addition, with the improvement of automobile performance and the development of the road network, improvement in steering stability with respect to tires, particularly improvement in handling stability at high speeds, is required.

  As a filler for a tire rubber composition, carbon black is widely used in terms of reinforcement and wear resistance. However, when a large amount of carbon black is blended in the base tread, the rigidity of the tread portion is increased and the steering stability is improved, but the fuel efficiency is lowered.

  In order to reduce fuel consumption by blending carbon black, a method of reducing the blending amount of carbon black is known. However, reducing carbon black improves fuel efficiency but decreases rigidity (steering stability). As described above, it has been difficult to improve the handling stability and the low fuel consumption at the same time.

  Patent Documents 1 and 2 propose a technique for improving the dispersibility of carbon black by blending a specific amine compound to improve low heat generation. However, there is still room for improvement in terms of improving fuel efficiency while maintaining the rubber strength obtained by blending carbon black. There is also a problem of poor workability.

  Patent Document 3 proposes a technique for improving the dispersibility of carbon black by adding a rubber / carbon black coupling agent containing a specific sulfide compound, thereby improving low heat buildup. However, there is still room for improvement in terms of improving fuel efficiency while maintaining the rubber strength obtained by blending carbon black. There is also a problem of poor workability.

Japanese Patent No. 2912845 JP 2011-16984 A JP 2013-23610 A

  An object of the present invention is to provide a tire including a base tread composed of a rubber composition excellent in fuel efficiency while maintaining excellent rubber processability and handling stability due to carbon black content.

  The present invention contains a rubber component, carbon black, and a sulfide compound having a nitrogen functional group, the rubber component is polymerized by a lithium initiator, the tin atom content is 50 to 3000 ppm, and the vinyl bond content is 5 to 50. 5% to 50% by mass of a tin-modified polybutadiene rubber having a molecular weight distribution (Mw / Mn) of 2.0 or less, and the carbon black content relative to 100 parts by mass of the rubber component is 15 to 50 parts by mass, The present invention relates to a tire including a base tread composed of a rubber composition having a content of the sulfide compound having a nitrogen functional group of 0.05 to 15 parts by mass with respect to 100 parts by mass of carbon black.

The nitrogen adsorption specific surface area of the carbon black is the 50~125m ² / g, it is preferably dibutyl phthalate absorption is 70~155cm ³ / 100g.

（式中、Ｒ¹は、水素原子、炭素数１〜６の直鎖状または分岐状のアルキル基もしくはアルケニル基、または炭素数３〜６の環状のアルキル基またはアルケニル基を表す。Ａは、Ｏ、Ｓ、ＮＨ、またはＮＲ²を表す。Ｒ²は、炭素数１〜６の直鎖状または分岐状のアルキル基もしくはアルケニル基、または炭素数３〜６の環状のアルキル基もしくはアルケニル基を表す。ｎは１〜６の整数を表し、ｘは１〜４の整数を表す。） The sulfide compound having a nitrogen functional group is preferably a compound represented by the following formula (I).

(In the formula, R ¹ represents a hydrogen atom, a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms, or a cyclic alkyl group or alkenyl group having 3 to 6 carbon atoms. O, S, NH, or NR ^2. R ² represents a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms, or a cyclic alkyl group or alkenyl group having 3 to 6 carbon atoms. N represents an integer of 1 to 6, and x represents an integer of 1 to 4.)

The nitrogen adsorption specific surface area of the sulfide compound having a nitrogen functional group is preferably 2.0 m ² / g or more.

  It is preferable to contain the sulfide compound having a nitrogen functional group as an oil-extended product in which 5 to 40 parts by mass of oil is added to 100 parts by mass of the compound.

  The tire of the present invention comprises a rubber composition containing a predetermined tin-modified polybutadiene rubber (tin-modified BR) and a predetermined amount of carbon black, and further containing a sulfide compound having a nitrogen functional group. By providing the tire with the base tread, it is possible to provide a tire that can improve fuel efficiency while maintaining rubber processability and steering stability.

  The tire of the present invention is a tire including a base tread composed of a rubber composition containing a predetermined rubber component, a predetermined amount of carbon black, and a sulfide compound having a nitrogen functional group.

  The rubber component is polymerized with a lithium initiator, tin-modified polybutadiene having a tin atom content of 50 to 3000 ppm, a vinyl bond content of 5 to 50% by mass, and a molecular weight distribution (Mw / Mn) of 2.0 or less. Contains rubber (tin-modified BR).

  As the tin-modified BR, for example, one obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound can be used. Further, tin-end-modified BR in which the end of the modified BR molecule is bonded by a tin-carbon bond is preferable.

  Examples of the lithium initiator include lithium and lithium compounds such as alkyl lithium, aryl lithium, allyl lithium, vinyl lithium, organic tin lithium, and organic nitrogen lithium. By using lithium or a lithium compound as an initiator, a tin-modified BR having a high vinyl content and a low cis content can be produced.

  Examples of tin compounds include tin tetrachloride, butyltin trichloride, dibutyltin dichloride, dioctyltin dichloride, tributyltin chloride, triphenyltin chloride, diphenyldibutyltin, triphenyltin ethoxide, diphenyldimethyltin, ditolyltin chloride, diphenyltin dichloride. Examples include octanoate, divinyldiethyltin, tetrabenzyltin, dibutyltin distearate, tetraallyltin, and p-tributyltin styrene. These may be used alone or in combination of two or more. .

  The content of tin atoms in the tin-modified BR is 50 ppm or more, preferably 60 ppm or more, and more preferably 100 ppm or more. When the content of tin atoms is less than 50 ppm, the effect of improving the dispersibility of the filler in the tin-modified BR becomes small, and the fuel efficiency tends to deteriorate. The tin atom content in the tin-modified BR is 3000 ppm or less, preferably 2500 ppm or less, more preferably 1500 ppm or less, and even more preferably 500 ppm or less. When the content of tin atoms exceeds 3000 ppm, the kneaded product is not well-organized and the edges are not aligned, so the extrudability of the kneaded product tends to deteriorate.

  The molecular weight distribution (Mw / Mn) of the tin-modified BR is 2.0 or less, preferably 1.8 or less, and more preferably 1.5 or less. When Mw / Mn exceeds 2.0, the dispersibility of the filler deteriorates and the fuel efficiency tends to deteriorate. The lower limit of Mw / Mn is not particularly limited, but is preferably 1.0 or more. In this specification, the number average molecular weight (Mn) and the weight average molecular weight (Mw) are gel permeation chromatograph (GPC) (GPC-8000 series, manufactured by Tosoh Corporation), detector: differential refractometer, column: It is determined by standard polystyrene conversion based on the measured value by TSKGEL SUPERMALTPORE HZ-M manufactured by Tosoh Corporation.

  The vinyl bond content of the tin-modified BR is 5% by mass or more, preferably 7% by mass or more. It is difficult to polymerize (manufacture) tin-modified BR having a vinyl bond amount of less than 5% by mass. Further, the vinyl bond amount of the tin-modified BR is 50% by mass or less, and preferably 20% by mass or less. When the amount of vinyl bonds in the tin-modified BR exceeds 50% by mass, the dispersibility of the filler tends to deteriorate and the tensile strength of the rubber composition tends to decrease. The vinyl bond amount (1,2-bond butadiene unit amount) is a value measured by infrared absorption spectrum analysis.

  The content of tin-modified BR in the rubber component is 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, and further preferably 20% by mass or more. When the content is less than 5% by mass, the fuel economy tends not to be improved sufficiently. The content of tin-modified BR is 50% by mass or less, preferably 45% by mass or less, and more preferably 40% by mass or less. When content exceeds 50 mass%, there exists a tendency for the breaking strength of a rubber composition to fall.

  The rubber component that can be used in the present invention in addition to the tin-modified BR is not particularly limited. Natural rubber (NR), isoprene rubber (IR), butadiene rubber other than tin-modified BR (other BR), styrene-butadiene rubber ( Examples include diene rubbers such as SBR), chloroprene rubber (CR) styrene isoprene butadiene rubber (SIBR), styrene isoprene rubber (SIR), and isoprene butadiene rubber (IBR). These rubber components may be used alone or in combination of two or more. Among them, it is preferable to use NR together with tin-modified BR because it is possible to achieve both low fuel consumption and handling stability.

  The NR is not particularly limited, and examples thereof include those commonly used in the tire industry such as SIR20, RSS # 3, TSR20, and the like. Epoxidized natural rubber (ENR), deproteinized natural rubber (DPNR), and the like can also be used.

  When NR is contained, the content of NR in the rubber component is preferably 50% by mass or more, more preferably 55% by mass or more, and further preferably 60% by mass or more. When the content is less than 50% by mass, the reinforcing property tends to be insufficient. Moreover, 90 mass% or less is preferable, as for content of NR, 85 mass% or less is more preferable, and 80 mass% or less is further more preferable. When the content exceeds 90% by mass, the workability tends to be insufficient.

  Other BRs are not particularly limited, and for example, BR having a cis content of 95% by mass or more (BR) containing high syndiotactic polybutadiene crystals (SPB-containing BR) can be used. Examples of high-sis BR include BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B manufactured by Ube Industries, Ltd., and BR150B, and examples of SPB-containing BR include VCR412 and VCR617 manufactured by Ube Industries, Ltd. .

The carbon black nitrogen adsorption specific surface area (N ₂ SA) is preferably at least 50 m ² / g, more preferably at least 55m ² / g, more preferably not less than ^{58m 2 / g, 62m 2 /} g or more is particularly preferable. When N ₂ SA is less than 50 m ² / g, there is a tendency that sufficient tensile strength cannot be obtained. Further, N ₂ SA of carbon black is preferably 125 m ² / g or less, more preferably 115 m ² / g or less, further preferably 100 m ² / g or less, and particularly preferably 90 m ² / g or less. If N ₂ SA exceeds 125 m ² / g, processability and fuel efficiency may be deteriorated. In the present invention, N ₂ SA of carbon black is a value measured according to JIS K 6217 method A.

Dibutyl phthalate (DBP) oil absorption of carbon black is preferably at least 70cm ^3/100 g, more preferably at least 90cm ^3/100 g, more preferably not less than 103cm ³ / 100g. If the DBP oil absorption is less than 70cm ^3/100 g, there is a tendency that sufficient rubber strength can not tend secured, the reinforcing property becomes insufficient. Further, DBP oil absorption of carbon black is preferably not more than 155cm ^3/100 g, more preferably at most 150 cm ^3/100 g. If the DBP oil absorption exceeds 155cm ³ / 100g, processability tends to be insufficient. The DBP oil absorption of carbon black is a value measured according to JIS K6221.

  Content with respect to 100 mass parts of rubber components of carbon black is 15 mass parts or more, 20 mass parts or more are preferable and 25 mass parts or more are more preferable. When the content is less than 15 parts by mass, the rubber strength tends to be low, the rubber rigidity tends to be low, and the steering stability tends to be low. The carbon black content is 50 parts by mass or less, preferably 48 parts by mass or less, more preferably 47 parts by mass or less, and further preferably 45 parts by mass or less. When the content exceeds 50 parts by mass, the fuel efficiency tends to be insufficient.

式中、Ｒ¹は、水素原子、炭素数１〜６の直鎖状もしくは分岐状のアルキル基またはアルケニル基、または炭素数３〜６の環状のアルキル基またはアルケニル基を表す。Ａは、Ｏ、Ｓ、ＮＨ、またはＮＲ²を表す。Ｒ²は、炭素数１〜６の直鎖状もしくは分岐状のアルキル基またはアルケニル基、または炭素数３〜６の環状のアルキル基またはアルケニル基を表す。ｎは１〜６の整数を表し、ｘは１〜４の整数を表す。 Examples of the sulfide compound having a nitrogen functional group include sulfide compounds having a nitrogen functional group represented by the following formula (I). Among these, a sulfide compound having a nitrogen functional group represented by the following formula (I) is preferable because it is excellent in fuel efficiency.

In the formula, R ¹ represents a hydrogen atom, a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms, or a cyclic alkyl group or alkenyl group having 3 to 6 carbon atoms. A represents O, S, NH, or NR ² . R ² represents a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms, or a cyclic alkyl group or alkenyl group having 3 to 6 carbon atoms. n represents an integer of 1 to 6, and x represents an integer of 1 to 4.

  Examples of the sulfide compound represented by the formula (I) include 2,2′-bis (benzimidazolyl-2) ethyl sulfide, 2,2′-bis (benzimidazolyl-2) ethyl disulfide, and 2,2′-bis. (Benzimidazolyl-2) ethyl trisulfide, 2,2′-bis (benzimidazolyl-2) ethyl tetrasulfide, 3,3′-bis (benzimidazolyl-2) propyl disulfide, 3,3′-bis (benzimidazolyl) -2) propyl trisulfide, 3,3'-bis (benzimidazolyl-2) propyl tetrasulfide, 4,4'-bis (benzimidazolyl-2) butyl disulfide, 4,4'-bis (benzimidazolyl-2) Butyl trisulfide, 4,4'-bis (benzimidazolyl-2) butyl tetrasulfate 5,5′-bis (benzimidazolyl-2) pentyl disulfide, 5,5′-bis (benzimidazolyl-2) pentyl trisulfide, 5,5′-bis (benzimidazolyl-2) pentyl tetrasulfide, 6,6′-bis (benzimidazolyl-2) hexyl disulfide, 6,6′-bis (benzimidazolyl-2) hexyl trisulfide, 6,6′-bis (benzimidazolyl-2) hexyl tetrasulfide, 2,2 '-Bis (1-methylbenzimidazolyl-2) ethyl disulfide, 2,2'-bis (4-methylbenzimidazolyl-2) ethyl disulfide, 2,2'-bis (5-methylbenzimidazolyl-2) ethyl disulfide 3,3′-bis (1-methylbenzimidazolyl-2) propyldisulfur 3,3′-bis (4-methylbenzimidazolyl-2) propyl disulfide, 3,3′-bis (5-methylbenzimidazolyl-2) propyl disulfide, 2,2′-bis (1-ethylbenz) Imidazolyl-2) ethyl disulfide, 2,2′-bis (4-ethylbenzimidazolyl-2) ethyl disulfide, 2,2′-bis (5-ethylbenzimidazolyl-2) ethyl disulfide, 3,3′-bis ( 1-ethylbenzimidazolyl-2) propyl disulfide, 3,3′-bis (4-ethylbenzimidazolyl-2) propyl disulfide, 3,3′-bis (5-ethylbenzimidazolyl-2) propyl disulfide, 3,3 '-Bis (1-n-propylbenzimidazolyl-2) propyl disulfide, 3,3'-bi (4-n-propylbenzimidazolyl-2) propyl disulfide, 3,3′-bis (5-n-propylbenzimidazolyl-2) propyl disulfide, 3,3′-bis (1-isopropylbenzimidazolyl-2) Propyl disulfide, 3,3′-bis (4-isopropylbenzimidazolyl-2) propyl disulfide, 3,3′-bis (5-isopropylbenzimidazolyl-2) propyl disulfide, 3,3′-bis (1-tert- Butylbenzimidazolyl-2) propyl disulfide, 3,3′-bis (4-tert-butylbenzimidazolyl-2) propyl disulfide, 3,3′-bis (5-tert-butylbenzimidazolyl-2) propyl disulfide, 2 , 2'-bis (benzoxazolyl-2) Disulfide, 2,2'-bis (benzoxazolyl-2) ethyl trisulfide, 2,2'-bis (benzoxazolyl-2) ethyl tetrasulfide, 3,3'-bis (benzoxazolyl) -2) propyl disulfide, 4,4'-bis (benzoxazolyl-2) butyl disulfide, 5,5'-bis (benzoxazolyl-2) pentyl disulfide, 6,6'-bis (benzoxazolyl) 2) hexyl disulfide, 2,2′-bis (4-methylbenzoxazolyl-2) ethyl disulfide, 2,2′-bis (4-methylbenzoxazolyl-2) ethyl trisulfide, 2, 2′-bis (4-methylbenzoxazolyl-2) ethyl tetrasulfide, 2,2′-bis (5-methylbenzoxazolyl-2) ethyl dis Fido, 2,2′-bis (5-methylbenzoxazolyl-2) ethyl trisulfide, 2,2′-bis (5-methylbenzoxazolyl-2) ethyl tetrasulfide, 3,3′-bis (6-Methylbenzoxazolyl-2) propyl disulfide, 3,3′-bis (6-methylbenzoxazolyl-2) propyl trisulfide, 3,3′-bis (6-methylbenzoxazolyl- 2) propyl tetrasulfide, 2,2′-bis (benzthiazolyl-2) ethyl disulfide, 2,2′-bis (benzthiazolyl-2) ethyl trisulfide, 2,2′-bis (benzthiazolyl-2) ethyl tetrasulfide, 3,3′-bis (benzthiazolyl-2) propyl disulfide, 4,4′-bis (benzthiazolyl-2) butyl disulfide Fido, 5,5′-bis (benzthiazolyl-2) pentyl disulfide, 6,6′-bis (benzthiazolyl-2) hexyl disulfide, 3,3′-bis (4-methylbenzthiazolyl-2) propyl disulfide, 3,3′-bis (4-methylbenzthiazolyl-2) propyl trisulfide, 3,3′-bis (4-methylbenzthiazolyl-2) propyl tetrasulfide, 3,3′-bis (5 -Ethylbenzthiazolyl-2) propyl disulfide, 3,3'-bis (5-ethylbenzthiazolyl-2) propyl trisulfide, 3,3'-bis (5-ethylbenzthiazolyl-2) Propyl tetrasulfide, 3,3′-bis (6-n-propylbenzthiazolyl-2) propyl disulfide, 3,3′-bis (6-n-propiyl) Benzthiazolyl-2) propyl trisulfide, 3,3′-bis (6-n-propylbenzthiazolyl-2) propyl tetrasulfide, 3,3′-bis (7-isopropylbenzthiazolyl-2) propyl disulfide 3,3′-bis (7-isopropylbenzthiazolyl-2) propyl trisulfide, 3,3′-bis (7-isopropylbenzthiazolyl-2) propyl tetrasulfide, and the like. These sulfide compounds can be used alone or in combination.

Since the sulfide compound represented by the formula (I) has an aromatic condensed heterocyclic ring in the molecule, in addition to the bond due to the acid-base interaction with the carbon black surface, π with the benzene ring on the carbon black surface. A bond is formed by electronic interaction. Moreover, a bond with a polymer is formed by a reaction with a polymer radical by a sulfur moiety (S _X ) or a reaction involving sulfur crosslinking. Thereby, the dispersibility in the rubber composition of carbon black can be improved and the dispersion state can be maintained. Moreover, since carbon black is restrained, heat generation can be suppressed.

  The sulfide compound having a nitrogen functional group, particularly the sulfide compound represented by the formula (I) is usually a solid powder, but using a fine particle powder having a small average particle diameter can improve the dispersibility in the rubber composition. It is preferable because of improvement. The method for forming the sulfide compound into fine particles is not particularly limited, but can be carried out by airflow jet mill pulverization or dry pulverization.

The nitrogen adsorption specific surface area (N ₂ SA) of the fine particle powder of sulfide compound having a nitrogen functional group is preferably 2.0 m ² / g or more, more preferably 2.5 m ² / g or more, and 5.0 m ² / g or more. More preferred is 10.0 m ² / g or more. When N ₂ SA is less than 2.0 m ² / g, the average particle size is large and the dispersibility in the rubber composition tends to be insufficient. Further, the upper limit of N ₂ SA of the fine particle powder is not particularly limited, but is preferably set to 100 m ² / g or less because the cost increases. In addition, N ₂ SA of the sulfide compound in the present invention is a value measured according to JIS K 6217 method A as in the case of carbon black.

  The sulfide compound having a nitrogen functional group is preferably contained as an oil-extended product to which oil is added because the particles of the sulfide compound can be easily adapted to the rubber component and the dispersibility can be improved. The amount of oil added is preferably 5 parts by mass or more and more preferably 10 parts by mass or more with respect to 100 parts by mass of the sulfide compound. When the addition amount is less than 5 parts by mass, the effect of improving dispersibility tends to be insufficient. The amount of oil added is preferably 40 parts by mass or less, and more preferably 30 parts by mass or less. When the addition amount exceeds 40 parts by mass, the content ratio of the sulfide compound in the oil-extended product is lowered and the content efficiency is deteriorated. Further, the rubber composition is softened, and the handling performance of a tire using the rubber composition tends to deteriorate.

  The content of the sulfide compound having a nitrogen functional group with respect to 100 parts by mass of carbon black is 0.05 parts by mass or more, preferably 0.10 parts by mass or more, more preferably 0.20 parts by mass or more, and 0.50 parts by mass. Part or more is more preferable. When the content of the sulfide compound is less than 0.05 parts by mass, the effect of containing the sulfide compound having a nitrogen functional group tends to be difficult to obtain. Moreover, content of the sulfide compound which has a nitrogen functional group is 15 mass parts or less, 14 mass parts or less are preferable and 13 mass parts or less are more preferable. When the content of the sulfide compound exceeds 15 parts by mass, workability tends to deteriorate. When using an oil-extended product to which oil is added as a sulfide compound having a nitrogen functional group, the content of the sulfide compound having a nitrogen functional group indicates the content of the sulfide compound having a nitrogen functional group excluding the oil component. .

  In addition to the above components, the rubber composition according to the present invention is a compounding agent generally used in the production of rubber compositions, for example, reinforcing fillers other than carbon black such as silica, calcium carbonate, clay, and coupling agents. , Zinc oxide, stearic acid, various anti-aging agents, oils such as aroma oil (if the sulfide compound is an oil-extended product, oils other than the oil-extended oil), softeners, waxes, vulcanizing agents such as sulfur, various A vulcanization accelerator or the like can be suitably contained.

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

  1.0 mass part or more is preferable and, as for content with respect to 100 mass parts of rubber components in the case of containing an anti-aging agent, 1.3 mass parts or more are more preferable. Moreover, 2.0 mass parts or less are preferable and, as for content of an anti-aging agent, 1.7 mass parts or less are more preferable. When adjusted within the above range, the effects of the present invention can be obtained satisfactorily.

  When the oil is contained (in the case where the sulfide compound is an oil-extended product, the oil content other than the oil-extended oil) is preferably 5 parts by mass or more and more preferably 6 parts by mass or more with respect to 100 parts by mass of the rubber component. preferable. The oil content is preferably 8.5 parts by mass or less, and more preferably 7.5 parts by mass or less. By setting the oil content within the above range, the effects of the present invention can be obtained satisfactorily.

  Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Agents. These vulcanization accelerators may be used alone or in combination of two or more. Of these, sulfenamide-based vulcanization accelerators are preferred because of their excellent vulcanization characteristics and low fuel consumption in the rubber properties after vulcanization. For example, N-tert-butyl-2-benzothiazoli Examples include rusulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N, N′-dicyclohexyl-2-benzothiazolylsulfenamide (DZ), and TBBS is more preferable. .

  1.0 mass part or more is preferable and, as for content with respect to 100 mass parts of rubber components in the case of containing a vulcanization accelerator, 1.3 mass parts or more are more preferable. When the amount is less than 1.0 part by mass, the rubber composition is not sufficiently vulcanized, and the required rubber properties may not be obtained. The amount of the vulcanization accelerator is preferably 2.0 parts by mass or less, and more preferably 1.7 parts by mass or less. If it exceeds 2.0 parts by mass, there is a risk of burning the rubber.

  It does not specifically limit as a manufacturing method of the rubber composition which concerns on this invention, A well-known method can be used. For example, each of the above components can be produced by a method of kneading using a rubber kneading apparatus such as an open roll, a Banbury mixer, a closed kneader, and then vulcanizing.

  The tire of the present invention has a base tread composed of the rubber composition. The base tread is an inner layer portion of a tread having a multilayer structure. In a tread having a two-layer structure (a surface layer (cap tread) and an inner surface layer (base tread)), it is an inner surface layer. The tire of the present invention can be manufactured by a usual method. That is, the rubber composition according to the present invention, in which the above-mentioned compounding agent is blended as necessary with respect to the rubber component, is extruded in accordance with the shape of the base tread at an unvulcanized stage, and other on a tire molding machine. The tire of the present invention is manufactured by pasting together with the tire member and forming an unvulcanized tire by molding by a normal method, and heating and pressurizing the unvulcanized tire in a vulcanizer. Can do.

  The tire of the present invention can be used for passenger cars, trucks, buses, motorcycles (motorcycles) and the like, and in particular, can be suitably used for passenger cars and motorcycles (motorcycles).

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

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
Tin-modified BR: BR1250 manufactured by Nippon Zeon Co., Ltd. (polymerized using lithium as an initiator, vinyl bond content: 10 to 13% by mass, Mw / Mn: 1.5, tin atom content: 250 ppm, polystyrene conversion Content of components having a molecular weight of 10 ⁵ or less: 2 to 3% by mass, tin terminal modified BR)
NR: RSS # 3
Carbon black: DIA black manufactured by Mitsubishi Chemical _{(Co.) N330 (N 2 SA: 79m} 2 / g, DBP oil absorption: 105 cm ^3/100 g)
Sulfide compound 1: 2EBZ (2,2′-bis (benzimidazolyl-2) ethyl disulfide manufactured by Shikoku Kasei Kogyo Co., Ltd., R ¹ in formula (I) is a hydrogen atom, A is NH, n is 2, x 2, N ₂ SA: 10.5m ² / g, no oil exhibition)
Sulfide compound 2: Oil-extended product obtained by adding 30 parts by mass of oil to 100 parts by mass of sulfide compound 1 (added oil: Process Oil X-40 manufactured by Japan Energy Co., Ltd.)
Zinc oxide: Zinc Hua 1 manufactured by Mitsui Mining & Smelting Co., Ltd.
Aroma oil: Process oil X-140 manufactured by Japan Energy Co., Ltd.
Wax: Sunnock anti-aging agent manufactured by Ouchi Shinsei Chemical Co., Ltd .: NOCRACK 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shin Chemical Co., Ltd. )
Sulfur: Powder sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd .: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide (TBBS)) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

Examples 1-9, Comparative Examples 1 and 2
According to the formulation shown in Table 1, using a 1.7 L closed Banbury mixer, chemicals other than sulfur and a vulcanization accelerator were kneaded for 4 minutes at 150 ° C. to obtain a kneaded product. Next, using an open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 3 minutes at 80 ° C. to obtain an unvulcanized rubber composition. Furthermore, the obtained unvulcanized rubber composition was press vulcanized for 20 minutes at 160 ° C. to obtain a vulcanized rubber composition (sheet).

  The obtained unvulcanized rubber composition and vulcanized rubber composition were used for evaluation by the following methods. The evaluation results are shown in Table 1.

<Workability test>
For each unvulcanized rubber composition, according to the Mooney viscosity measuring method according to JIS K 6300-1, “Unvulcanized rubber—physical properties—Part 1: Determination of viscosity and scorch time using Mooney viscometer” Mooney viscosity (ML _{1 + 4} ) was measured under a temperature condition of 130 ° C. The results are expressed as an index according to the following calculation formula, assuming that the Mooney viscosity of Comparative Example 1 is 100. The larger the workability index, the lower the Mooney viscosity and the better the workability.
(Processability index) = (ML _{1 + 4} of Comparative Example 1) / (ML _{1 + 4 of} each formulation) × 100

<Tensile test>
The vulcanized rubber composition was subjected to a tensile test according to JIS K 6251, and the elongation at break was measured. The results are shown by an index according to the following calculation formula with the elongation at break of Comparative Example 1 as 100. The larger the rubber strength index, the better the rubber strength.
(Rubber strength index) = (breaking elongation of each compound) / (breaking elongation of Comparative Example 1) × 100

<Viscoelasticity test>
Using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd., hysteresis loss (tan δ), complex of vulcanized rubber composition at 70 ° C. under conditions of initial strain of 10%, dynamic strain amplitude of 1% and frequency of 10 Hz The elastic modulus (E *) was measured.
Low fuel consumption index The results are expressed as an index according to the following calculation formula, where tan δ of Comparative Example 1 is 100. The larger the fuel efficiency index, the better the rolling resistance characteristic (low fuel efficiency).
(Low fuel consumption index) = (tan δ of Comparative Example 1) / (tan δ of each formulation) × 100
Steering stability index The results are shown as an index according to the following calculation formula with E * of Comparative Example 1 being 100. The larger the steering stability index, the higher the rubber rigidity and the better the steering stability.
(Steering stability index) = (E * of each formulation) / (E * of Comparative Example 1) × 100

  From the results shown in Table 1, the rubber composition containing a predetermined tin-modified BR-containing rubber component, a predetermined amount of carbon black, and a sulfide compound having a nitrogen functional group, while maintaining rubber processability and steering stability, It can be seen that the fuel efficiency is excellent.

Claims (3)

Rubber component, carbon black and the following formula (I)

(In the formula, R ¹ represents a hydrogen atom, a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms, or a cyclic alkyl group or alkenyl group having 3 to 6 carbon atoms. O, S, NH, or NR ^2. R ² represents a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms, or a cyclic alkyl group or alkenyl group having 3 to 6 carbon atoms. N represents an integer of 1 to 6, and x represents an integer of 1 to 4.)
A sulfide compound having a nitrogen functional group represented by
The rubber component is polymerized with 50% by mass or more of natural rubber and a lithium initiator, the content of tin atoms is 50 to 3000 ppm, the amount of vinyl bonds is 5 to 50% by mass, and the molecular weight distribution (Mw / Mn) is 2. Containing 5 to 50% by mass of tin-modified polybutadiene rubber of 0.0 or less,
The nitrogen adsorption specific surface area of the sulfide compound having a nitrogen functional group is 2.0 m ² / g or more,
The rubber composition has a carbon black content of 15 to 50 parts by mass with respect to 100 parts by mass of the rubber component, and a nitrogen compound-containing sulfide compound content of 0.05 to 15 parts by mass with respect to 100 parts by mass of carbon black A tire with a base tread composed of objects . The nitrogen adsorption specific surface area of the carbon black is the 50~125m ² / g, a tire according to claim 1, wherein dibutyl phthalate absorption is 70~155cm ³ / 100g. The tire according to claim 1 or 2 , comprising the sulfide compound having a nitrogen functional group as an oil-extended product obtained by adding 5 to 40 parts by mass of oil to 100 parts by mass of the compound.