JP2020070320A - Rubber composition - Google Patents

Abstract

To provide a rubber composition capable of improving wear resistance performance and low fuel consumption performance in a well-balanced manner, and a tire having a tire member composed of the rubber composition.SOLUTION: The rubber composition contains 8-110 pts.mass of carbon black based on 100 pts.mass of a diene rubber and contains 0.30 pt.mass or more of a carbon surface modifier containing a compound represented by formula (1) based on 100 pts.mass of the carbon black. (In the formula, ring Qrepresents a benzene ring which may be substituted with 1-3 groups selected from the group consisting of a halogen atom, a hydroxyl group, an amino group, a nitro group, a Calkyl group, a Calkoxy group and a Calkyl-carbonyl group; and ring Qrepresents an imidazole ring which may be substituted with 1-2 groups selected from the group consisting of a halogen atom, a hydroxyl group, an amino group, a nitro group, a Calkyl group, a Calkoxy group and a Calkyl-carbonyl group.)SELECTED DRAWING: None

Description

  The present invention relates to a tire having a rubber composition and a tread composed of the rubber composition.

  As one of the methods for improving the wear resistance performance of tires, a technique of making carbon black into fine particles is known. However, since atomization of carbon black causes deterioration of fuel economy performance, it is difficult to achieve both wear resistance performance and fuel economy performance.

  In order to solve this problem, for example, the carbon coupling agents described in Patent Documents 1 to 3 are used, and the carbon black and the diene rubber are chemically bonded to each other to improve the dispersion of the carbon black and improve the fuel economy. Attempts have been made to improve performance.

JP, 2016-3236, A JP, 2016-216595, A JP, 2017-8230, A

  However, when a carbon coupling agent is used, stress concentration occurs between the carbon and the diene rubber, and as a result, the wear resistance performance deteriorates, so it is not sufficient to achieve both wear resistance performance and fuel economy performance. I knew it was.

  It is an object of the present invention to provide a rubber composition capable of improving wear resistance performance and fuel economy performance in a well-balanced manner, and a tire having a tread composed of the rubber composition.

  As a result of intensive studies, the present inventor has found that a rubber composition containing carbon black and a carbon surface modifier containing a compound represented by the formula (1) improves the overall performance of abrasion resistance and fuel economy. The inventors have found that they can be achieved and completed the present invention.

（式中、環Ｑ¹は、ハロゲン原子、水酸基、アミノ基、ニトロ基、Ｃ_1-6アルキル基、Ｃ_1-6アルコキシ基、およびＣ_1-6アルキル−カルボニル基からなる群から選ばれる１〜３個の基で置換されていてもよいベンゼン環を表し；環Ｑ²は、ハロゲン原子、水酸基、アミノ基、ニトロ基、Ｃ_1-6アルキル基、Ｃ_1-6アルコキシ基、およびＣ_1-6アルキル−カルボニル基からなる群から選ばれる１〜２個の基で置換されていてもよいイミダゾール環を表す。）
〔２〕加硫後のゴム組成物を、アセトンを溶剤として用いて８０℃で７２時間ソックスレー抽出したときの式（２）で表される化合物の抽出量が、カーボンブラック１００質量部に対して０．１０質量部以上である、〔１〕記載のゴム組成物。

（環Ｑ²は、ハロゲン原子、水酸基、アミノ基、ニトロ基、Ｃ_1-6アルキル基、Ｃ_1-6アルコキシ基、およびＣ_1-6アルキル−カルボニル基からなる群から選ばれる１〜２個の基で置換されていてもよいイミダゾール環を表す。）
〔３〕〔１〕または〔２〕記載のゴム組成物より構成されたトレッドを有する重荷重用タイヤ、に関する。 That is, the present invention is
[1] 8 to 110 parts by mass of carbon black is mixed with 100 parts by mass of diene rubber, and 100 parts by mass of the carbon black is modified to contain a compound represented by the formula (1). A rubber composition containing 0.30 parts by mass or more of an agent.

(In the formula, ring Q ¹ is 1 selected from the group consisting of a halogen atom, a hydroxyl group, an amino group, a nitro group, a C _1-6 alkyl group, a C _1-6 alkoxy group, and a C _1-6 alkyl-carbonyl group. ~ Represents a benzene ring which may be substituted with 3 groups; ring Q ² is a halogen atom, a hydroxyl group, an amino group, a nitro group, a C _1-6 alkyl group, a C _1-6 alkoxy group, and C _{1 -6} represents an imidazole ring which may be substituted with 1 to 2 groups selected from the group consisting of ₆ alkyl-carbonyl groups.)
[2] The amount of the compound represented by the formula (2) when the rubber composition after vulcanization was subjected to Soxhlet extraction at 80 ° C. for 72 hours using acetone as a solvent, based on 100 parts by mass of carbon black. The rubber composition according to [1], which is 0.10 parts by mass or more.

(Ring Q ² is 1 to 2 selected from the group consisting of a halogen atom, a hydroxyl group, an amino group, a nitro group, a C _1-6 alkyl group, a C _1-6 alkoxy group, and a C _1-6 alkyl-carbonyl group. Represents an imidazole ring which may be substituted with a group of
[3] A heavy-duty tire having a tread composed of the rubber composition according to [1] or [2].

  According to the present invention, there are provided a rubber composition capable of improving wear resistance performance and fuel economy performance in a well-balanced manner, and a tire having a tread composed of the rubber composition.

  A rubber composition which is one embodiment of the present invention is characterized by blending carbon black and a carbon surface modifier containing a compound represented by the formula (1). In addition, in this specification, when a numerical range is shown using "-", the numerical value of the both ends shall be included.

In the present specification, the number of carbon atoms in the definition of “substituent” may be expressed as “C _1-6 ”, for example. Specifically, the expression “C _1-6 alkyl” is synonymous with an alkyl group having 1 to 6 carbon atoms.

  Specific examples of the “halogen atom” include a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. Preferred are a fluorine atom and a chlorine atom.

“C _1-6 alkyl” means a linear or branched saturated hydrocarbon group having 1 to 6 carbon atoms. Specific examples of "C _1-6 alkyl" include, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, 1-ethylpropyl, hexyl, isohexyl, Heptyl, octyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 2-ethylbutyl and the like can be mentioned. It is preferably “C _1-4 alkyl”, more preferably methyl and ethyl.

The “C _1-6 alkyl” portion of “C _1-6 alkoxy” has the same _{meaning as} the above “C _1-6 alkyl”. Specific examples of "C _1-6 alkoxy" include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy, hexyloxy and the like. It is preferably “C _1-4 alkoxy”, more preferably methoxy and ethoxy.

The “C _1-6 alkyl” portion of “C _1-6 alkyl-carbonyl” has the same _{meaning as} the above “C _1-6 alkyl”. Specific examples of “C _1-6 alkyl-carbonyl” include methylcarbonyl (acetyl), ethylcarbonyl, propylcarbonyl, isopropylcarbonyl, butylcarbonyl, pentylcarbonyl, hexylcarbonyl and the like. It is preferably “C _1-4 alkyl-carbonyl”, more preferably acetyl.

<Rubber component>
The rubber component used in this embodiment is not particularly limited as long as it is a diene rubber, but isoprene rubber and butadiene rubber (BR) are preferably used.

(Isoprene rubber)
As the isoprene-based rubber, for example, isoprene rubber (IR) and natural rubber such as those commonly used in the tire industry can be used. In addition to unmodified natural rubber (NR), natural rubber includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), and graft. Modified natural rubber such as synthetic natural rubber is also included. Among them, NR and IR are preferable, and IR is more preferable. These other isoprene-based rubbers may be used alone or in combination of two or more.

  The NR is not particularly limited, and those commonly used in the tire industry can be used, and examples thereof include SIR20, RSS # 3, and TSR20.

  The content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more. The upper limit of the content is not particularly limited and may be 100% by mass, preferably 95% by mass or less, more preferably 90% by mass or less, and further preferably 85% by mass or less.

(BR)
The BR is not particularly limited, and examples thereof include BR having a cis 1,4 bond content of less than 50% (low cis BR), BR having a cis 1,4 bond content of 90% or more (high cis BR), and rare earth. Rare earth butadiene rubber synthesized using elemental catalyst (rare earth BR), BR containing syndiotactic polybutadiene crystals (SPB containing BR), modified BR (high cis modified BR, low cis modified BR) etc. It is possible to use a specific one. Among these BRs, high cis BR is preferable because it has excellent wear resistance.

  Examples of the high cis BR include BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B, BR150B, BR150L manufactured by Ube Industries, Ltd., and BR730 manufactured by JSR Corporation. By containing high cis BR, low temperature characteristics and wear resistance can be improved. Examples of the rare earth BR include BUNA-CB25 manufactured by LANXESS Co., Ltd. and the like.

  Examples of the SPB-containing BR include those in which 1,2-syndiotactic polybutadiene crystals are not simply dispersed in BR but are dispersed after being chemically bonded to BR. Examples of such SPB-containing BR include VCR-303, VCR-412 and VCR-617 manufactured by Ube Industries, Ltd.

  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 with a tin-carbon bond (tin. Modified BR), butadiene rubber having a condensed alkoxysilane compound at the active end of butadiene rubber (modified BR for silica), and the like. Examples of such a modified BR include BR1250H (tin modified) manufactured by Nippon Zeon Co., Ltd., S-modified polymer (modified for silica) manufactured by Sumitomo Chemical Co., Ltd., and the like.

  When BR is contained, the content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass or more. The content is preferably 30% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less.

  The cis-1,4 bond content (cis content) of BR is preferably 90% by mass or more, more preferably 93% by mass or more, and further preferably 95% by mass or more, from the viewpoint of durability and abrasion resistance. It is considered that the higher the cis content, the more regularly the polymer chains are arranged, so that the interaction between the polymers becomes stronger, the rubber strength is improved, and the wear resistance performance is improved.

  The weight average molecular weight (Mw) of BR is preferably 300,000 or more, more preferably 350,000 or more, and further preferably 400,000 or more from the viewpoint of wear resistance performance and grip performance. Further, Mw is preferably 2,000,000 or less, and more preferably 1,000,000 or less from the viewpoint of cross-linking uniformity and the like. In addition, Mw is based on the measured value by gel permeation chromatography (GPC) (Tosoh Corp. GPC-8000 series, a detector: differential refractometer, a column: Tosoh Corp. TSKGEL SUPERMALTORE HZ-M). Can be obtained by standard polystyrene conversion.

(Other rubber components)
As the rubber component according to the present embodiment, a diene rubber other than the above isoprene rubber and BR may be contained. Examples of the diene rubber include styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), halogenated butyl rubber (X-IIR), styrene isoprene butadiene rubber (SIBR), etc. Is mentioned. These other rubber components may be used alone or in combination of two or more.

  The rubber composition according to the present embodiment may be blended with, for example, a composite material containing a functional group having at least one kind of metal coordinating ability in the molecular structure. Here, the functional group having a metal coordinating ability is not particularly limited as long as it has a metal coordinating ability, and examples thereof include a functional group containing a metal coordinating atom such as oxygen, nitrogen, or sulfur. Be done. Specific examples thereof include a dithiocarbamic acid group, a phosphoric acid group, a carboxylic acid group, a carbamic acid group, a dithioacid group, an aminophosphoric acid group and a thiol group. The above functional groups may be contained alone or in combination of two or more.

Examples of the coordination metal for the functional group include Fe, Cu, Ag, Co, Mn, Ni, Ti, V, Zn, Mo, W, Os, Mg, Ca, Sr, Ba, Al and Si. Be done. For example, in a polymer material containing such a compound having a metal atom (M ¹ ) and containing a functional group (—COO or the like) having a metal coordinating ability, each —COOM ¹ is coordinate-bonded to form a large number of compounds. The overlapping of —COOM ¹ forms a cluster in which metal atoms are aggregated. The content of the metal atom (M ¹ ) is preferably 0.01 to 200 parts by mass with respect to 100 parts by mass of the polymer component in the polymer material.

<Carbon black>
As the carbon black, those generally used for rubber can be appropriately used. Specifically, N110, N115, N120, N125, N134, N135, N219, N220, N231, N234, N293, N299, N326, N330, N339, N343, N347, N351, N356, N358, N375, N539, N550 ,. N582, N630, N642, N650, N660, N683, N754, N762, N765, N772, N774, N787, N907, N908, N990, N991, etc. can be preferably used, and in-house synthesized products are also suitable. Can be used for. These carbon blacks may be used alone or in combination of two or more.

Nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably not less than 50 m ² / g from the viewpoint of the reinforcing property, more preferably at least 60m ² / g, 70m ² / more preferably more than g, 80 m ² / g or more Is particularly preferable. Further, from the viewpoint of fuel economy, preferably it is 400 meters ² / g or less, more preferably 350 meters ² / g, more preferably 300 meters ² / g or less. In addition, in this embodiment, N ₂ SA of carbon black is measured in accordance with the method A of JIS K 6217.

  From the viewpoint of abrasion resistance, the content of carbon black with respect to 100 parts by mass of the rubber component is 8 parts by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and further preferably 20 parts by mass or more. Further, from the viewpoint of low fuel consumption performance and processability, it is 110 parts by mass or less, preferably 105 parts by mass or less, more preferably 100 parts by mass or less, further preferably 90 parts by mass or less, particularly preferably 80 parts by mass or less. ..

（式中、環Ｑ¹は、ハロゲン原子、水酸基、アミノ基、ニトロ基、Ｃ_1-6アルキル基、Ｃ_1-6アルコキシ基、およびＣ_1-6アルキル−カルボニル基からなる群から選ばれる１〜３個の基で置換されていてもよいベンゼン環を表し；環Ｑ²は、ハロゲン原子、水酸基、アミノ基、ニトロ基、Ｃ_1-6アルキル基、Ｃ_1-6アルコキシ基、およびＣ_1-6アルキル−カルボニル基からなる群から選ばれる１〜２個の基で置換されていてもよいイミダゾール環を表す。） <Carbon surface modifier>
The rubber composition according to this embodiment contains a carbon surface modifier containing one or more compounds represented by the following formula (1). A carbon surface modifier composed of the compound represented by the formula (1) is preferable.

(In the formula, ring Q ¹ is 1 selected from the group consisting of a halogen atom, a hydroxyl group, an amino group, a nitro group, a C _1-6 alkyl group, a C _1-6 alkoxy group, and a C _1-6 alkyl-carbonyl group. ~ Represents a benzene ring which may be substituted with 3 groups; ring Q ² is a halogen atom, a hydroxyl group, an amino group, a nitro group, a C _1-6 alkyl group, a C _1-6 alkoxy group, and C _{1 -6} represents an imidazole ring which may be substituted with 1 to 2 groups selected from the group consisting of ₆ alkyl-carbonyl groups.)

  The compound represented by the formula (1) does not bond the carbon black and the diene rubber unlike the existing carbon coupling agent, but bonds only to the surface of the carbon black. Then, by improving the compatibility between the carbon black and the diene rubber, it is possible to improve the dispersibility of the carbon black and secure the low fuel consumption performance. Furthermore, by preventing stress concentration between the carbon black and the diene rubber, the wear resistance performance can be improved.

Ring Q ¹ is preferably substituted with 1 to 3 groups selected from the group consisting of halogen atom, hydroxyl group, amino group, C _1-4 alkyl group, C _1-4 alkoxy group, and acetyl group. And a benzene ring which may be substituted with 1 to 3 groups selected from the group consisting of a halogen atom, a C _1-4 alkyl group, and a C _1-4 alkoxy group. ..

Ring Q ² is preferably substituted with 1 to 2 groups selected from the group consisting of a halogen atom, a hydroxyl group, an amino group, a C _1-4 alkyl group, a C _1-4 alkoxy group, and an acetyl group. A good imidazole ring; more preferably an imidazole ring optionally substituted with 1 to 2 groups selected from the group consisting of a halogen atom, an amino group, and a C _1-4 alkyl group; , An imidazole ring substituted with 1 to 2 C _1-4 alkyl groups. The bond to the carbonyl group on the imidazole ring may be either a carbon atom or a nitrogen atom constituting the ring.

  The blending amount of the carbon surface modifier with respect to 100 parts by mass of carbon black is 0.30 part by mass or more, preferably 0.40 part by mass or more, more preferably 0.50 part by mass or more, and 1.0 part by mass or more. Is more preferable. When the blending amount of the carbon surface modifier is less than 0.30 parts by mass, the effect of carbon surface modification cannot be sufficiently exerted, and the effect of improving wear resistance performance and fuel economy performance can be sufficiently obtained. Tend not to. The upper limit of the amount of the carbon surface modifier blended is not particularly limited, but is preferably 50 parts by mass or less, and 45 parts by mass or less from the viewpoint of cost and the saturation of the effect of improving wear resistance performance and fuel efficiency performance. Is more preferable, and 40 parts by mass or less is further preferable.

（環Ｑ²は、ハロゲン原子、水酸基、アミノ基、ニトロ基、Ｃ_1-6アルキル基、Ｃ_1-6アルコキシ基、およびＣ_1-6アルキル−カルボニル基からなる群から選ばれる１〜２個の基で置換されていてもよいイミダゾール環を表す。） When binding the carbon black and the carbon black surface modifier, the amide bond of the compound represented by the formula (1) undergoes a hydrolysis reaction in the kneading process and is cleaved, resulting in a compound having an amino group. It bonds with the functional groups on the surface of carbon black. On the other hand, the carboxylic acid represented by the following formula (2) generated as a result of hydrolysis can be recovered by Soxhlet extraction of the vulcanized rubber.

(Ring Q ² is 1 to 2 selected from the group consisting of a halogen atom, a hydroxyl group, an amino group, a nitro group, a C _1-6 alkyl group, a C _1-6 alkoxy group, and a C _1-6 alkyl-carbonyl group. Represents an imidazole ring which may be substituted with a group of

Ring Q ² is preferably substituted with 1 to 2 groups selected from the group consisting of a halogen atom, a hydroxyl group, an amino group, a C _1-4 alkyl group, a C _1-4 alkoxy group, and an acetyl group. A good imidazole ring; more preferably an imidazole ring optionally substituted with 1 to 2 groups selected from the group consisting of a halogen atom, an amino group, and a C _1-4 alkyl group; , An imidazole ring substituted with 1 to 2 C _1-4 alkyl groups. The bond to the carbonyl group on the imidazole ring may be either a carbon atom or a nitrogen atom constituting the ring.

  The rubber composition after vulcanization was subjected to Soxhlet extraction at 80 ° C. for 72 hours using acetone as a solvent according to the method A described in JIS K 6229: 2015 “Rubber-Method for determining solvent-solvent extract (quantitative)”. The extraction amount of the compound represented by the formula (2) is preferably 0.10 parts by mass or more, more preferably 0.20 parts by mass or more, still more preferably 0.30 parts by mass or more with respect to 100 parts by mass of carbon black. , 0.40 parts by mass or more is particularly preferable. If the extraction amount is less than 0.10 parts by mass, the effect of carbon surface modification cannot be sufficiently exerted, and the effect of improving wear resistance performance and fuel economy performance tends to be insufficient. Further, the upper limit of the amount of the compound represented by the formula (2) is not particularly limited, but from the viewpoint of saturation of the effect of improving wear resistance performance and fuel economy performance, 40 parts by mass or less is preferable, and 35 parts by mass or less is preferable. It is more preferably 30 parts by mass or less.

<Other compounding agents>
In the rubber composition produced in the present embodiment, in addition to the above components, compounding agents generally used in the production of rubber compositions, for example, reinforcing fillers such as silica, silane coupling agents, and antioxidants. , Stearic acid, zinc oxide, a processing aid, a softening agent, a vulcanizing agent, a vulcanization accelerator and the like can be appropriately mixed.

Examples of the filler include mM ² · xSiOy · zH ₂ O (wherein M ² is at least one metal selected from the group consisting of aluminum, calcium, magnesium, titanium and zirconium, or an oxide of the metal, A hydroxide, a hydrate or a carbonate; m is 1 to 5, x is 0 to 10, y is 2 to 5, and z is a numerical value in the range of 0 to 10.) Etc.

Specific examples of the filler represented by the above-mentioned mM ² · xSiOy · zH ₂ O include aluminum hydroxide (Al (OH) ₃ ), alumina (Al ₂ O ₃ , Al ₂ O ₃ · 3H ₂ O), and clay. (Al ₂ O ₃ .2SiO ₂ ), kaolin (Al ₂ O ₃ .2SiO ₂ .2H ₂ O), pyrophyllite (Al ₂ O ₃ .4SiO ₂ .H ₂ O), bentonite (Al ₂ O ₃ .4SiO) ₂ · 2H ₂ O), aluminum silicate _{(Al 2 SiO 5, Al 4} (SiO 2) 3 · 5H 2 O , etc.), aluminum silicate calcium _{(Al 2 O 3 · CaO ·} 2SiO 2), calcium hydroxide ( Ca (OH) ₂ ), calcium oxide (CaO), calcium silicate (Ca ₂ SiO ₄ ), magnesium calcium silicate (CaMgSiO ₄ ), magnesium hydroxide (Mg (OH) ₂ ), magnesium oxide (M gO), talc _{(MgO · 4SiO 2 · H 2} O), attapulgite _{(5MgO · 8SiO 2 · 9H 2} O), magnesium aluminum oxide _{(MgO · Al 2 O 3)} , titanium white (TiO _2), titanium black (Ti _n O _2n-1 ) and the like. In the rubber composition containing such a filler, clusters in which the filler is aggregated are formed. The amount of the filler to be blended is preferably 10 to 200 parts by mass with respect to 100 parts by mass of the rubber component.

  As the silane coupling agent, any silane coupling agent that has been conventionally used in combination with silica in the tire industry can be used, and for example, a sulfide-based compound such as bis (3-triethoxysilylpropyl) tetrasulfide, 3 or the like. -Mercapto type such as mercaptopropyltrimethoxysilane, vinyl type such as vinyltriethoxysilane, amino type such as 3-aminopropyltriethoxysilane, glycidoxy type such as γ-glycidoxypropyltriethoxysilane, 3-nitropropyl Examples thereof include nitro-based compounds such as trimethoxysilane and chloro-based compounds such as 3-chloropropyltrimethoxysilane. These may be used alone or in combination of two or more. Among them, sulfides are preferable, and bis (3-triethoxysilylpropyl) tetrasulfide is more preferable.

  The antioxidant is not particularly limited, and those used in the rubber field can be used, and examples thereof include quinoline-based, quinone-based, phenol-based, and phenylenediamine-based antioxidants.

  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, and more preferably 0.8 part by mass or more. The content of the antioxidant is preferably 2.0 parts by mass or less, more preferably 1.5 parts by mass or less, and 1.2 parts by mass, from the viewpoints of dispersibility of the filler and the like, elongation at break, and kneading efficiency. Less than or equal to part is more preferable.

  From the viewpoint of the vulcanization rate, the content of stearic acid with respect to 100 parts by mass of the rubber component is preferably 0.2 parts by mass or more, and more preferably 1 part by mass or more. From the viewpoint of workability, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

  From the viewpoint of the vulcanization rate, the content of 100 parts by mass of the rubber component in the case of containing zinc oxide is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more. From the viewpoint of wear resistance, the amount is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

  Examples of the softening agent include oils such as process oils and vegetable oils and fats, and liquid diene polymers. These softening agents may be used alone or in combination of two or more kinds. Of these, oil is preferable.

  Examples of oils include process oils, vegetable oils and fats, mixtures thereof, and the like. Examples of the process oil include paraffin type process oil, naphthene type process oil, aromatic type process oil (aroma oil) and the like. As vegetable oils and oils, castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, sesame oil, Beni flower oil, sesame oil, Examples include olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil and the like. Among them, aroma oil is preferable.

  The content of the softening agent with respect to 100 parts by mass of the rubber component is preferably 1 part by mass or more, and more preferably 3 parts by mass or more, from the viewpoint of processability. In addition, the content of the softening agent is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, from the viewpoint of block resistance and abrasion resistance.

  Sulfur is preferably used as the vulcanizing agent. As sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur and the like can be used.

  The content of 100 parts by mass of the rubber component when sulfur is contained as a vulcanizing agent is 0.5 parts by mass or more from the viewpoint of ensuring a sufficient vulcanization reaction and obtaining good grip performance and abrasion resistance. It is preferably 1.0 part by mass or more. From the viewpoint of deterioration, the amount is preferably 3.0 parts by mass or less, more preferably 2.5 parts by mass or less.

  Examples of the vulcanization accelerator include sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline-based, or xanthate-based vulcanization accelerators. Etc. These vulcanization accelerators may be used alone or in combination of two or more kinds. Of these, sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, and guanidine-based vulcanization accelerators are preferable, and sulfenamide-based vulcanization accelerators are more preferable.

  Examples of the sulfenamide vulcanization accelerator include N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), and N, N. -Dicyclohexyl-2-benzothiazolylsulfenamide (DCBS) and the like. Among them, N-tert-butyl-2-benzothiazolylsulfenamide (TBBS) and N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) are preferable.

  The content of the vulcanization accelerator with respect to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, and more preferably 1.0 part by mass or more from the viewpoint of ensuring a sufficient vulcanization rate. Further, the content of the vulcanization accelerator is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, from the viewpoint of suppressing blooming.

  The method for producing the rubber composition 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.

<Tires>
The tire which is one embodiment of the present invention can be manufactured by a usual method using the above-mentioned rubber composition. That is, the rubber composition prepared by optionally blending the compounding agent with respect to the rubber component is extruded in accordance with the shape of the base tread, and is bonded together with other tire members on a tire molding machine, A tire can be manufactured by forming an unvulcanized tire by molding by the method and heating and pressurizing this unvulcanized tire in a vulcanizer.

  The tire can be used for tires for passenger cars, high-performance tires for passenger cars, tires for heavy loads such as trucks and buses, tires for competition, etc., but it is preferably used as a heavy load tire because of its excellent wear resistance. To be done.

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

カーボンカップリング剤：下記式で表される化合物

酸化亜鉛：三井金属鉱業（株）製の亜鉛華１号
ステアリン酸：日油（株）製のステアリン酸「椿」
老化防止剤：大内新興化学（株）製のノクラック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、６ＰＰＤ）
硫黄：軽井沢硫黄（株）製の粉末硫黄
加硫促進剤：大内新興化学工業（株）製のノクセラーＣＺ（Ｎ−シクロヘキシル−２−ベンゾチアゾリルスルフェンアミド） Various chemicals used in Examples and Comparative Examples will be described.
IR: Nippon IR2200 manufactured by Nippon Zeon Co., Ltd.
BR: UBEPOL BR150B (Mw: 440,000, high cis BR, cis-1,4 bond content: 96%) manufactured by Ube Industries, Ltd.
Carbon black: Show black N234 (N ₂ SA: 117 m ² / g) manufactured by Cabot Japan Co., Ltd.
Carbon surface modifier: compound represented by the following formula

Carbon coupling agent: compound represented by the following formula

Zinc oxide: Zinc Hua No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Stem acid "Tsubaki" manufactured by NOF CORPORATION
Anti-aging agent: Nocrac 6C (N- (1,3-dimethylbutyl) -N-phenyl-p-phenylenediamine, 6PPD) manufactured by Ouchi Shinko Chemical Co., Ltd.
Sulfur: Powder sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd .: Nocceller CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Co., Ltd.

(Examples and Comparative Examples)
According to the formulation shown in Table 1, using a 3 L closed Banbury mixer, the chemicals other than sulfur and the vulcanization accelerator were kneaded at 150 ° C. for 4 minutes to obtain a kneaded product. Next, using an open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded at 80 ° C. for 3 minutes to obtain an unvulcanized rubber composition. Further, the obtained unvulcanized rubber composition was press-vulcanized at 140 ° C. for 50 minutes to obtain a vulcanized rubber composition (sheet).

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

<Viscoelasticity test>
Using a spectrometer manufactured by Ueshima Seisakusho, tan δ was measured at a dynamic strain amplitude of 1%, a frequency of 10 Hz and a temperature of 60 ° C. The value of the reciprocal of tan δ obtained was indexed with Comparative Example 1 as 100. The larger the value, the smaller the energy loss and the better the fuel efficiency.

<Abrasion test>
The amount of wear was measured using a Lambourn wear tester under the conditions of room temperature, a load of 1.0 kgf and a slip ratio of 30%. The value of the reciprocal of the obtained wear amount was indexed with Comparative Example 1 set to 100. The larger the value, the higher the abrasion resistance.

  From the results of Table 1, the rubber composition of the present invention containing the carbon surface modifier containing the carbon black and the compound represented by the formula (1) has an average index of 100 for wear resistance and low fuel consumption. From this, it can be seen that the overall performance of wear resistance performance and fuel efficiency performance has been improved.

<Soxhlet extraction>
Each vulcanized rubber composition was subjected to Soxhlet extraction at 80 ° C. for 72 hours at 80 ° C. using acetone as a solvent according to the method A described in JIS K 6229: 2015 “Rubber-Determination of Solvent Extraction (Quantification)”. The extraction amount (parts by mass) of the compound represented by the following formula based on 100 parts by mass of the rubber component is shown below.

  The rubber composition of the present invention has good wear resistance and low fuel consumption performance, and thus is particularly suitable for use as a tread rubber for heavy-duty tires.

Claims (3)

8 to 110 parts by mass of carbon black is mixed with 100 parts by mass of the diene rubber, and 0 parts by mass of the carbon surface modifier containing the compound represented by the formula (1) is mixed with 100 parts by mass of the carbon black. A rubber composition comprising 30 parts by mass or more.

(In the formula, ring Q ¹ is 1 selected from the group consisting of a halogen atom, a hydroxyl group, an amino group, a nitro group, a C _1-6 alkyl group, a C _1-6 alkoxy group, and a C _1-6 alkyl-carbonyl group. ~ Represents a benzene ring which may be substituted with 3 groups; ring Q ² is a halogen atom, a hydroxyl group, an amino group, a nitro group, a C _1-6 alkyl group, a C _1-6 alkoxy group, and C _{1 -6} represents an imidazole ring which may be substituted with 1 to 2 groups selected from the group consisting of ₆ alkyl-carbonyl groups.) The amount of the compound represented by the formula (2) when the rubber composition after vulcanization was subjected to Soxhlet extraction at 80 ° C. for 72 hours using acetone as a solvent was 0.10 with respect to 100 parts by mass of carbon black. The rubber composition according to claim 1, which is contained in an amount of at least part by mass.

(Ring Q ² is 1 to 2 selected from the group consisting of a halogen atom, a hydroxyl group, an amino group, a nitro group, a C _1-6 alkyl group, a C _1-6 alkoxy group, and a C _1-6 alkyl-carbonyl group. Represents an imidazole ring which may be substituted with a group of A heavy duty tire having a tread made of the rubber composition according to claim 1.