JP2019157042A - Tire rubber composition - Google Patents

Abstract

To provide a tire rubber composition improved in silica dispersibility, and a tire having a tire member formed from the rubber composition.SOLUTION: The tire rubber composition contains a diene rubber, silica, a silane coupling agent, and a compound represented by the formula (I). In the formula, n represents an integer from 7 to 30. The content of the silane coupling agent is 1-20 mass% based on the mass of the silica.SELECTED DRAWING: None

Description

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

  Important performances of tires include wet grip performance and wear resistance to improve safety during driving. In recent years, from the standpoint of resource saving, it is necessary to improve fuel efficiency by improving tire rolling resistance. As a method of improving fuel economy and wet grip performance in a well-balanced manner, for example, a method of blending silica and a silane coupling agent is known (Patent Document 1).

JP 2004-059599 A

  However, silica has strong self-aggregation due to the formation of hydrogen bonds due to silanol groups present on the particle surface, and its affinity with the rubber component is lower than that of carbon black, resulting in insufficient dispersion in the rubber composition. It is easy to become. For this reason, problems such as deterioration in workability due to an increase in Mooney viscosity of the rubber composition during kneading, an increase in viscosity due to aging of the unvulcanized rubber, wear resistance and deterioration in mechanical strength of the rubber composition may occur. .

  Further, when natural rubber is used as the rubber component, there is a problem that the dispersibility of silica cannot be ensured because impurities contained in the natural rubber inhibit the reaction of the silane coupling agent.

  When a processing aid such as zinc stearate is used as a silica dispersant, dispersibility can be ensured, but the molecular chain of the rubber component is broken by the crushing effect by metal ions, and the breaking strength tends to decrease. is there.

  An object of the present invention is to provide a tire rubber composition having improved dispersibility of silica, and a tire having a tire member composed of the rubber composition.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by blending silica and a predetermined alkanediol in a diene rubber. In a more preferred embodiment, the present inventors have found that the viscosity increase, fuel efficiency, and breaking characteristics of the unvulcanized rubber can be improved due to the change over time.

（式中、ｎは、７〜３０の整数を表す）で表される化合物を含有し、シランカップリング剤をシリカの質量に対し１〜２０質量％含有するタイヤ用ゴム組成物、
〔２〕式（Ｉ）で表される化合物をシリカの質量に対し１〜２０質量％含有する、〔１〕に記載のタイヤ用ゴム組成物、
〔３〕ジエン系ゴム１００質量部に対し、シリカを３０質量部以上含有する、〔１〕または〔２〕に記載のタイヤ用ゴム組成物、
〔４〕脂肪酸金属塩の含有量が、ジエン系ゴム１００質量部に対し２質量部未満である、〔１〕〜〔３〕のいずれかに記載のタイヤ用ゴム組成物、
〔５〕ジエン系ゴム中に７０質量％以上の天然ゴムを含有する、〔１〕〜〔４〕のいずれかに記載のタイヤ用ゴム組成物、
〔６〕〔１〕〜〔５〕のいずれかに記載のタイヤ用ゴム組成物により構成されたタイヤ部材を有するタイヤ、に関する。 That is, the present invention
[1] Diene rubber, silica, silane coupling agent, and formula (I)

(Wherein n represents an integer of 7 to 30), and a rubber composition for tires containing 1 to 20% by mass of a silane coupling agent based on the mass of silica,
[2] The rubber composition for tires according to [1], containing 1 to 20% by mass of the compound represented by the formula (I) with respect to the mass of silica.
[3] The rubber composition for tires according to [1] or [2], containing 30 parts by mass or more of silica with respect to 100 parts by mass of the diene rubber.
[4] The tire rubber composition according to any one of [1] to [3], wherein the content of the fatty acid metal salt is less than 2 parts by mass with respect to 100 parts by mass of the diene rubber.
[5] The tire rubber composition according to any one of [1] to [4], wherein the diene rubber contains 70% by mass or more of natural rubber.
[6] The present invention relates to a tire having a tire member made of the tire rubber composition according to any one of [1] to [5].

  The tire rubber composition according to the present invention has good silica dispersibility.

  The rubber composition for tires according to one embodiment of the present invention is characterized by containing a diene rubber, silica, a silane coupling agent, and a predetermined alkanediol.

  Since the two hydroxyl groups of alkanediol are adsorbed to the silanol group on the silica surface, alkanediol and silica have high affinity and silica self-aggregation can be suppressed. Further, the carbon chain portion of the alkanediol acts as a hydrophobizing site, and the alkanediol and the diene rubber have high affinity, so that the viscosity of the rubber composition can be reduced. As described above, the alkanediol interacts with the silica and the diene rubber, respectively, so that the dispersion of the silica in the rubber can be promoted.

  By improving the dispersibility of silica, silica agglomeration in the unvulcanized rubber is prevented, and for example, an increase in viscosity due to aging can be expected. In addition, since the dispersibility of silica is improved in the rubber after vulcanization, a reduction in heat generation is expected due to the improved dispersibility. Furthermore, when tensile strain is applied to the rubber, it is possible to prevent the rubber from being broken due to silica agglomeration as a starting point, so that improvement in breaking characteristics such as breaking strength and breaking elongation can be expected.

  In addition, since the dispersibility of silica is improved, the amount of processing aid containing metal ions as a dispersant can be reduced, and the decrease in breaking strength due to the crushing effect of metal ions can be suppressed. it can.

  In addition, in this specification, when a numerical range is shown using "-", it shall include the numerical value of the both ends.

<Rubber component>
As the rubber component used in the present embodiment, a diene rubber is preferably used. Examples of the diene rubber include natural rubber, isoprene rubber (IR), styrene butadiene rubber (SBR), butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and halogenated. Examples thereof include butyl rubber (X-IIR) and styrene isoprene butadiene rubber (SIBR). These can be used alone or as a blend of two or more. Among these, natural rubber is preferably used because good fracture characteristics can be obtained.

(Natural rubber)
The natural rubber used in this embodiment includes non-modified natural rubber (NR), epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high purity Modified natural rubbers such as natural rubber (UPNR) and grafted natural rubber are also included. These rubbers may be used alone or in combination of two or more.

  The natural rubber is not particularly limited, and those that are common in the tire industry can be used, and examples thereof include SIR20, RSS # 3, and TSR20.

  The content of the natural rubber in the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more from the viewpoint of breaking strength and elongation at break, and consists of only natural rubber (100 % By mass) is particularly preferred.

（式中、ｎは、７〜３０の整数を表す）で表される化学構造を有する。アルカンジオールの炭素鎖とジエン系ゴムとの親和性の観点から、ｎは７以上であり２０以上が好ましい。ｎを７以上、好ましくは２０以上とすることにより、シリカをゴム成分中に十分に分散させることができる。またｎが３０を超えると、破断強度が悪化する傾向がある。 <Alkanediol>
The alkanediol blended in the rubber composition according to this embodiment has the following formula (I)

(Wherein n represents an integer of 7 to 30). From the viewpoint of the affinity between the carbon chain of the alkanediol and the diene rubber, n is 7 or more, and preferably 20 or more. By setting n to 7 or more, preferably 20 or more, silica can be sufficiently dispersed in the rubber component. If n exceeds 30, the breaking strength tends to deteriorate.

  The content of the compound represented by the formula (I) is preferably 1% by mass or more, more preferably 3% by mass or more, and further preferably 5% by mass or more with respect to the mass of silica. Further, the content of the compound represented by the formula (I) is preferably 20% by mass or less, more preferably 18% by mass or less, and further preferably 15% by mass or less with respect to the mass of silica. If it is in the said range, a silica can be favorably disperse | distributed in a rubber component and the effect of this invention can fully be exhibited.

  1 mass part or more is preferable with respect to 100 mass parts of rubber components, as for content of the compound represented by Formula (I), 3 mass parts or more is more preferable, and 5 mass parts or more is further more preferable. Moreover, 20 mass parts or less are preferable with respect to 100 mass parts of rubber components, as for content of the compound represented by Formula (I), 18 mass parts or less are more preferable, and 15 mass parts or less are more preferable.

<Filler>
The filler used in this embodiment is characterized by containing silica as an essential component. Silica is preferably used in combination with a silane coupling agent.

(silica)
The silica is not particularly limited, and for example, silica generally used in the tire industry such as silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), and the like can be used. Of these, hydrous silica prepared by a wet method is preferred because of its large number of silanol groups. Silica may be used alone or in combination of two or more.

The BET specific surface area of silica is preferably 80 m ² / g or more, more preferably 100 m ² / g or more, from the viewpoint of durability and elongation at break. Further, BET specific surface area of the silica, from the viewpoint of fuel economy and workability, preferably 250 meters ² / g or less, more preferably 220 m ² / g. In addition, the BET specific surface area of the silica in this specification is a value measured by BET method according to ASTM D3037-93.

  30 mass parts or more are preferable with respect to 100 mass parts of rubber components, as for content of a silica, 35 mass parts or more are more preferable, and 40 mass parts or more are further more preferable. When the content of silica is less than 30 parts by mass, the silica is self-aggregated, and the rupture properties such as the rupture strength and the rupture elongation and the low fuel consumption tend to be deteriorated. Moreover, 120 mass parts or less are preferable with respect to 100 mass parts of rubber components, and, as for content of a silica, 110 mass parts or less are more preferable, and 100 mass parts or less are more preferable. By controlling the silica content to 120 parts by mass or less, deterioration of dispersibility of silica in rubber is suppressed, better fuel economy and workability tend to be obtained, and better wear resistance can be obtained. Tend.

(Silane coupling agent)
Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited, and any silane coupling agent conventionally used in combination with silica can be used in the rubber industry. Examples of such silane coupling agents include bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, bis ( 3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (4-trimethoxysilylbutyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (2- Triethoxysilylethyl) trisulfide, bis (4-triethoxysilylbutyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (2-trimethoxysilylethyl) trisulfide, bis (4-trimethoxy) Siri Butyl) 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, 3-triethoxysilylpropyl-N, N-dimethyl Thiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimeth Silane coupling agents having a sulfide group such as silylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-trimethoxysilylpropyl methacrylate monosulfide; 3-mercaptopropyltrimethoxysilane, 3 -Mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, a silane coupling agent having a mercapto group such as NXT-Z100, NXT-Z45, NXT manufactured by Momentive; vinyltriethoxy Silane coupling agents having a vinyl group such as silane and vinyltrimethoxysilane; 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-a Silane coupling agents having an amino group such as minoethyl) aminopropyltriethoxysilane and 3- (2-aminoethyl) aminopropyltrimethoxysilane; γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxy Glycidoxy silane coupling agents such as silane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane; nitro such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane Silane coupling agents of the type; chloro-type silane coupling agents such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane; Raising It is. These silane coupling agents may be used individually by 1 type, and may be used in combination of 2 or more type. Of these, sulfide type and mercapto type are preferable from the viewpoints of strong binding strength with silica and excellent fuel efficiency. Use of a mercapto type is also preferable from the viewpoint that the fuel efficiency and wear resistance can be suitably improved.

  The content in the case of containing a silane coupling agent is preferably 1% by mass or more, more preferably 2% by mass or more, based on the mass of silica, because the effects such as silica dispersibility and viscosity reduction are obtained. More preferably 4% by mass or more. Further, for the purpose of efficiently obtaining a sufficient coupling effect and silica dispersion effect to ensure reinforcement, 20% by mass or less is preferable, 18% by mass or less is more preferable, and 15% by mass with respect to the mass of silica. % Or less is more preferable.

  When the silane coupling agent is contained, the content relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and still more preferably 4 parts by mass or more. Moreover, 20 mass parts or less are preferable, as for content of a silane coupling agent, 18 mass parts or less are more preferable, and 15 mass parts or less are more preferable.

(Other fillers)
In addition to silica, other fillers may be used as the filler. Such a filler is not particularly limited, and for example, any filler generally used in this field such as carbon black, aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, talc, clay and the like is used. be able to. These fillers may be used alone or in combination of two or more. When using a filler other than silica, carbon black is preferred from the viewpoint of rubber strength. That is, the filler preferably contains silica and carbon black, or preferably consists only of silica and carbon black.

  As carbon black, those generally used for rubber can be appropriately used. Examples of carbon black include furnace black, acetylene black, thermal black, channel black, graphite, and the like. 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 and the like can be suitably used, and in-house synthesized products and the like can also be suitably used. These carbon blacks may be used alone or in combination of two or more.

BET specific surface area of the carbon black is preferably at least 80 m ² / g from the viewpoint of the reinforcing property, preferably at least ^{85m 2 / g, 90m 2 /} g or more is more preferable. Although not limit particularly limited BET specific surface area is preferably 180 m ² / g or less in view of workability, more preferably not more than 160 m ² / g, more preferably 150 meters ² / g or less. The BET specific surface area of carbon black in this specification is measured according to JIS K 6217-2 “Basic characteristics of carbon black for rubber—Part 2: Determination of specific surface area—Nitrogen adsorption method—Single point method”. Value.

  The content with respect to 100 parts by mass of the rubber component in the case of containing carbon black is preferably 1 part by mass or more, preferably 3 parts by mass or more, and more preferably 5 parts by mass or more from the viewpoint of wear resistance. The upper limit of the carbon black content is not particularly limited, but is preferably 100 parts by mass or less, more preferably 95 parts by mass or less, and still more preferably 90 parts by mass or less, from the viewpoints of low fuel consumption and workability.

  40 mass parts or more are preferable from a viewpoint of a fracture | rupture characteristic, as for content with respect to 100 mass parts of rubber components of the whole filler, 45 mass parts or more are more preferable, and 50 mass parts or more are further more preferable. Moreover, from a viewpoint of the dispersibility of silica, and a viewpoint of workability, 150 mass parts or less are preferable, 140 mass parts or less are more preferable, 130 mass parts or less are further more preferable.

  The content of silica in the filler is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more from the viewpoint of low fuel consumption and wet grip performance.

<Other ingredients>
In addition to the rubber components and fillers described above, the rubber composition according to the present embodiment includes compounding agents and additives conventionally used in the tire industry, such as processing aids, waxes, oils, anti-aging agents, stearins. An acid, zinc oxide, a vulcanizing agent, a vulcanization accelerator, and the like can be appropriately contained as necessary.

  Since the rubber composition according to the present embodiment has good silica dispersibility, the processing aid containing metal ions causes the molecular chain of the rubber component to be cut by the crushing effect by the metal ions, resulting in a decrease in breaking strength. The use of (particularly fatty acid metal salts such as zinc stearate) can be reduced, and it is preferable not to use it. When the processing aid containing metal ions is contained, the content relative to 100 parts by mass of the rubber component is preferably less than 2 parts by mass, and more preferably less than 1 part by mass. Examples of the processing aid include fatty acid soap-based processing aids such as EF44 and WB16 manufactured by Straktor.

  When the wax is contained, the content with respect to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more and more preferably 1 part by mass or more from the viewpoint of the weather resistance of the rubber. Moreover, from a viewpoint of the whitening of the tire by Bloom, 10 mass parts or less are preferable, and 5 mass parts or less are more preferable.

  The content with respect to 100 parts by mass of the rubber component in the case of containing oil is preferably 100 parts by mass or less, and more preferably 90 parts by mass or less, from the viewpoint of ensuring good wear resistance. Moreover, from a workability viewpoint, 5 mass parts or more are preferable and 10 mass parts or more are more preferable. Processability can also be ensured by the addition of surfactants, liquid resins, liquid polymers, etc.

  It does not specifically limit as an anti-aging agent, What is used in the rubber field | area can be used, For example, a quinoline type | system | group, a quinone type | system | group, a phenol type, a phenylenediamine type | system | group anti-aging agent etc. are mentioned.

  The content with respect to 100 parts by mass of the rubber component in the case of containing an anti-aging agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more from the viewpoint of ozone crack resistance of the rubber. Moreover, from a viewpoint of abrasion resistance performance and grip performance, 10 mass parts or less are preferable, and 5 mass parts or less are more preferable.

  In the case of containing stearic acid, the content 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 processability. Moreover, from a viewpoint of a vulcanization speed, 10 mass parts or less are preferable, and 5 mass parts or less are more preferable.

  In the case of containing zinc oxide, the content with respect to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more and more preferably 1 part by mass or more from the viewpoint of workability. Moreover, from a viewpoint of abrasion resistance performance, 10 mass parts or less are preferable, and 5 mass parts or less are more preferable.

  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 with respect to 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 securing a sufficient vulcanization reaction and obtaining good grip performance and wear resistance. Preferably, 1.0 mass part or more is more preferable. Moreover, from a viewpoint of deterioration, 3.0 mass parts or less are preferable, and 2.5 mass parts or less are more preferable.

  Examples of the vulcanizing agent other than sulfur include Takkol V200 manufactured by Taoka Chemical Industry Co., Ltd., DURALINK HTS (1,6-hexamethylene-sodium dithiosulfate dihydrate) manufactured by Flexis Co., LANXESS Co., Ltd. Examples thereof include a vulcanizing agent containing a sulfur atom such as KA9188 (1,6-bis (N, N′-dibenzylthiocarbamoyldithio) hexane), an organic peroxide such as dicumyl peroxide, and the like.

  Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, and xanthate vulcanization accelerators. Etc. These vulcanization accelerators may be used alone or in combination of two or more. Of these, sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, and guanidine vulcanization accelerators are preferable, and sulfenamide vulcanization accelerators are more preferable. A combination of a sulfenamide vulcanization accelerator and another vulcanization accelerator (preferably a thiazole vulcanization accelerator and / or a guanidine vulcanization accelerator) can also be mentioned as a preferred embodiment.

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

  Examples of the thiazole vulcanization accelerator include 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and the like. Of these, 2-mercaptobenzothiazole is preferable.

  Examples of the guanidine vulcanization accelerator include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, dicatechol borate di-o-tolylguanidine salt, 1, Examples include 3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, and the like. Of these, 1,3-diphenylguanidine is preferable.

  In the case of containing a vulcanization accelerator, the content with respect to 100 parts by mass of the rubber component is preferably 0.1 parts by mass or more, and more preferably 0.5 parts by mass or more from the viewpoint of vulcanization acceleration. Moreover, from a workability viewpoint, 5 mass parts or less are preferable, and 3 mass parts or less are more preferable.

<Manufacture of rubber composition and tire>
The rubber composition according to this embodiment can be produced by a known method. For example, each of the above components can be produced by a method of kneading using a rubber kneader such as an open roll, a Banbury mixer, a closed kneader, and then vulcanizing.

  Other embodiment of this invention is a tire which has a tire member comprised with the said rubber composition. Examples of the tire member made of the rubber composition include tire members such as a tread, an under tread, a carcass, a sidewall, and a bead. Among these, a tread is preferable because it has excellent wet grip performance, wear resistance performance, and abrasion performance.

  The tire according to this embodiment can be manufactured by a normal method using the rubber composition. That is, a non-vulcanized rubber composition obtained by kneading each of the above components is bonded together with other tire members on a tire molding machine by extruding a member that has been extruded according to the shape of a tire member such as a tread. An unvulcanized tire can be formed by molding by the method, and the unvulcanized tire can be manufactured by heating and pressing in a vulcanizer.

  The tire according to the present embodiment is suitable for competition tires, passenger car tires, large passenger car tires, large SUV tires, and motorcycle tires, and can be used as respective summer tires, winter tires, and studless tires.

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

Hereinafter, various chemicals used in Examples and Comparative Examples are collectively shown.
NR: TSR20
Carbon black: Show Black N339 (BET: 89 m ² / g) manufactured by Cabot Japan
Silica: Ultrasil VN3 manufactured by Evonik Degussa (N ₂ SA: 175 m ² / g, average primary particle size: 15 nm)
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) (Sulfur content: 0.7% by mass) manufactured by Evonik Degussa
Alkanediol 1: 1,2-decanediol (CAS number: 1119-86-4)
Alkanediol 2: hexacosane-1,2-diol (CAS number: 97338-12-0)
Aliphatic alcohol: stearyl alcohol (CAS number: 112-92-5)
Wax: Ozoace 0355 manufactured by Nippon Seiwa Co., Ltd.
Anti-aging agent: NOCRACK 6C (N- (1,3-dimethylbutyl) -N-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Fatty acid metal salt: calcium stearate (CAS number: 1592-23-0)
Stearic acid: Stearic acid “椿” manufactured by NOF Corporation
Zinc oxide: “Silver R” manufactured by Toho Zinc Co., Ltd.
Oil: Diana Process NH-70S manufactured by Idemitsu Kosan Co., Ltd.
Sulfur: HK-200-5 (5% oil-containing powder sulfur) manufactured by Hosoi Chemical Co., Ltd.
Vulcanization accelerator: Noxeller D (N, N'-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

(Examples and Comparative Examples)
According to the formulation shown in Table 1, using a 1.7 L Banbury mixer, chemicals other than sulfur and a vulcanization accelerator are kneaded for 5 minutes at a discharge temperature of 150 ° C. to obtain a kneaded product. Next, sulfur and a vulcanization accelerator are added to the kneaded product obtained as described above using an open roll and kneaded for 3 minutes to obtain an unvulcanized rubber composition. Further, the unvulcanized rubber composition thus obtained is press vulcanized for 30 minutes at 150 ° C. to obtain a test vulcanized rubber sheet.

<Silica dispersibility>
About each unvulcanized rubber composition, distortion 0.5, 1, 2, 4, 8, 16, 32, 64% on condition of 70 degreeC and 1 Hz using the RPA2000 type testing machine made from Alpha Technologies. G * of the silica is measured, the Pain effect ΔG * of silica is measured from the difference between the maximum value of G * and the minimum value of G *, and the reciprocal value of ΔG * is displayed as an index with Comparative Example 1 being 100. It shows that it is excellent in a silica dispersibility, so that a numerical value is large.
(Silica dispersibility index) = (ΔG * of Comparative Example 1) / (ΔG * of each formulation) × 100

<Processability>
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” The Mooney viscosity (ML _{1 + 4} ) is measured under a temperature condition of 130 ° C., and the reciprocal value of ML _{1 + 4} is indicated as an index with Comparative Example 1 being 100. It shows that it is excellent in the processability of rubber, so that a numerical value is large.
(Processability index) = (ML _{1 + 4} of Comparative Example 1) / (ML _{1 + 4 of} each formulation) × 100

<Mooney viscosity increase>
Each unvulcanized rubber composition immediately after the kneading was stored at room temperature for 7 days, and then Mooney viscosity (ML _{1 + 4} ) was measured at 130 ° C. in accordance with JIS K 6300-1, The difference from the Mooney viscosity (ML _{1 + 4} ) of each unvulcanized rubber composition immediately after kneading was determined, and this was used as the Mooney viscosity increase, and the value of Comparative Example 1 was set to 100 as the reciprocal value of the Mooney viscosity increase. As an exponent. The larger the value, the less the increase in viscosity due to the change with time and the better the stability of the viscosity.

<Low fuel consumption>
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), the loss tangent (tan δ) of each test vulcanized rubber sheet was measured under the conditions of a temperature of 30 ° C., an initial strain of 10%, and a dynamic strain of 2%. The reciprocal value of tan δ is displayed as an index with Comparative Example 1 being 100. Higher values indicate lower rolling resistance (less heat generation and lower energy loss) and better fuel efficiency.
(Low fuel consumption index) = (tan δ of Comparative Example 1) / (tan δ of each formulation) × 100

<Break strength>
Using a No. 3 dumbbell-shaped test piece comprising vulcanized rubber sheets for each test, a tensile test was carried out in accordance with JIS K 6251 “Vulcanized rubber and thermoplastic rubber-Determination of tensile properties” to obtain a breaking strength TB. (MPa) is measured, and the break strength TB of Comparative Example 1 is taken as 100 and displayed as an index. The larger the value, the better the rubber strength.

<Elongation at break>
Using a No. 3 dumbbell-shaped test piece comprising vulcanized rubber sheets for each test, a tensile test was conducted according to JIS K 6251 “Vulcanized rubber and thermoplastic rubber-Determination of tensile properties”, and the elongation at break EB (%) Is measured, and the elongation at break EB of Comparative Example 1 is taken as 100 and displayed as an index. The larger the value, the better the rubber strength.

  Each index or a value close to it is obtained by performing each of the above tests based on the blending contents of Table 1.

  In the present embodiment, the target value of the silica dispersibility index is not 100 or less.

Claims (6)

Diene rubber, silica, silane coupling agent, and formula (I)

(Wherein n represents an integer of 7 to 30),
A rubber composition for tires containing a silane coupling agent in an amount of 1 to 20% by mass based on the mass of silica. The rubber composition for tires of Claim 1 which contains 1-20 mass% of compounds represented by a formula (I) with respect to the mass of a silica. The rubber composition for tires according to claim 1 or 2 containing 30 mass parts or more of silica to 100 mass parts of diene rubber. The rubber composition for tires according to any one of claims 1 to 3 whose content of fatty acid metal salt is less than 2 mass parts to 100 mass parts of diene rubber. The rubber composition for tires according to any one of claims 1 to 4 which contains 70 mass% or more of natural rubber in diene system rubber. The tire which has a tire member comprised with the rubber composition for tires as described in any one of Claims 1-5.