JP2001164051A - Rubber composition for tire and pneumatic tire using the composition in tire tread - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a pneumatic tire having a low fuel cost, excellent abrasion resistance and processability. SOLUTION: This rubber composition for tire is characterized by compounding 100 pts.wt. of a rubber component with 5-80 pts.wt. of carbon black containing silica and carbon black and (or) silica so as to give 40-100 pts.wt. of the total of the carbon black containing silica and the carbon black and (or) the silica and a polymer having an alkylene oxide structure in an amount of 2-20 wt.% based on the total of the carbon black containing silica and the silica.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for a tire having low fuel consumption, high abrasion resistance and good workability, and a pneumatic tire using the same in a tire tread.

[0002]

2. Description of the Related Art With the recent increase in awareness of the prevention of global warming, the demand for lower fuel consumption of automobiles has been increasing. To meet this demand, tires have been developed in which carbon black is replaced with carbon black, which has a good balance between low fuel consumption performance and wet grip performance, instead of conventional carbon black.

[0003] However, a rubber composition in which silica is blended with a reduced amount of carbon black has a marked decrease in abrasion resistance as compared with a conventional rubber composition in which carbon black is blended, and in particular, wear resistance under severe conditions. There is a disadvantage that the property is inferior. As one of the measures to suppress the reduction in wear resistance, the vulcanization accelerator is changed or its amount is increased. However, there is a problem that the physical properties of the rubber after vulcanization are changed, which is not sufficient. As another measure, a silica surface-treated carbon black in which silica having both the characteristics of both carbon black and silica fillers is adhered to the surface of carbon black has been developed, and a rubber composition for tire tread mixed with a rubber component has been developed. Although disclosed (Japanese Patent No. 2788212), satisfactory performance has not been obtained.

On the other hand, according to Japanese Patent Application No. 11-295758, a rubber composition for a tire tread containing a silica-containing carbon black in which silica and carbon black are mixed three-dimensionally has the above-mentioned problems. Although it can be overcome, the processability of the unvulcanized rubber of the composition is poor and there is a need for improvement.

Japanese Patent Application No. 11-210831 discloses a rubber composition for a tire tread comprising a silica-containing carbon black in which carbon black and silica are mixed three-dimensionally and a specific organopolysiloxane compound. Although the above problems can be overcome and the processability of the unvulcanized rubber can be improved, the cost of the organopolysiloxane is relatively high, and the cost of the rubber composition is relatively high. There is a problem that also rises.

[0006]

The inventor of the present invention has disclosed Japanese Patent Application No.
No. 2,295,758 discloses a rubber composition containing a silica-containing carbon black in which silica and carbon black are mixed three-dimensionally, since the temperature rise during kneading is relatively large. When a compound containing a sulfur atom is used as a coupling agent for bonding, a problem such as the start of a vulcanization reaction is considered to occur, and as a result of intensive studies, it has been found that silica-containing carbon in which carbon black is mixed three-dimensionally By blending a polymer having an alkylene oxide structure with black, it has been found that it is possible to suppress a rise in temperature during kneading, and as a result, fuel efficiency and wear resistance are further improved, and processability is also improved. It has been found that a good and inexpensive rubber composition for tire treads can be obtained, and the present invention has been completed. It was.

That is, according to the present invention, 5-80 parts of carbon black containing silica and carbon black and / or silica are added to 100 parts by weight (hereinafter referred to as "parts") of a rubber component. And carbon black and / or silica in a total amount of 40 to 100 parts, and a polymer having an alkylene oxide structure is added in an amount of 2 to the total amount of carbon black and silica containing silica.
A rubber composition for a tire (Claim 1), wherein the silane coupling agent is added in an amount of 3 to 20% by weight (hereinafter referred to as%) based on the total amount of the silica-containing carbon black and silica. Claim 1 containing 10% to 10%.
The present invention relates to a rubber composition for a tire (Claim 2) and a pneumatic tire using the rubber composition for a tire according to Claim 1 or 2 for a tire tread (Claim 3).

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber component used in the present invention comprises:
As long as it is generally used as a rubber component of a rubber composition for a tire, it can be used without any particular limitation.

Specific examples of the rubber component include natural rubber (NR), various butadiene rubbers (BR), various styrene-butadiene copolymer rubbers (SBR), polyisoprene (IR), butyl rubber (IIR), acrylonitrile- Butadiene rubber (NBR), acrylonitrile
Styrene-butadiene copolymer rubber, chlorobrene rubber,
Ethylene-propylene copolymer rubber, styrene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, isoprene-butadiene copolymer rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, fluorine rubber ,
Urethane rubber and the like. These may be used alone or as a blend of two or more. There is no particular limitation on the blend ratio when blending. Among them, NR, BR, SBR, IR, and a blend thereof are preferable from the viewpoint of obtaining a suitable wear resistance for a tire tread.

The silica-containing carbon black (hereinafter referred to as silica-containing carbon) used in the present invention is:
As described above, carbon black and silica are three-dimensionally mixed in one particle, and both silica and carbon black are exposed on the particle surface.

FIG. 1 schematically shows a state in which the carbon black and silica are mixed three-dimensionally in one particle. In FIG. 1, 1 represents a carbon black portion, and 2 represents a silica portion.

In the silica-containing carbon black, both the carbon black portion and the silica portion have portions that are exposed on the surface of the particles, and almost all of the carbon black is covered with silica like the silica surface-treated carbon black. Nothing. Therefore, the wear resistance of the tire under severe conditions, which is a feature of using carbon black, can be improved. In addition, since it contains silica, the number of functional groups (surface active points) present on the surface becomes larger than that of ordinary carbon black, it becomes easier to bond to the polymer via a binder, the number of bound rubbers becomes larger, and hysteresis is reduced. The rolling resistance can be reduced, and the rolling resistance can be reduced. As a result, both abrasion resistance and rolling resistance can be achieved.

The ratio of carbon black to silica in the silica-containing carbon black is such that the silica is 0.1 to 25%, more preferably 0.5 to 10
%, Especially 2 to 6%, is preferable in that the advantages of both carbon black and silica are exhibited in a well-balanced manner.

Although there is no particular limitation on the method for producing the silica-containing carbon black, a method in which an organic siloxane is reacted with a raw material oil at the same time, and the production is performed in one step, is preferred. Regarding the preferred production method, for example, WO 96/37
It is disclosed in detail in pamphlet No. 547.

The carbon black used in the present invention is:
It is a component used to ensure reinforcement.

As the carbon black, for example, those generally used for compounding general-purpose rubber are used.

Specific examples of the carbon black include:
For example, furnace black, acetylene black, thermal black, channel black, graphite and the like can be mentioned. These may be used alone or in combination of two or more.

[0018] The silica used in the present invention is also a component used for ensuring the reinforcing property.

As the silica, those generally used for compounding general-purpose rubber are used.

The specific surface area of the silica is not particularly limited. For example, CTAB adsorption specific surface area (hereinafter referred to as CTAB)
Hereinafter) is 100 to 200 m ² / g, BET nitrogen adsorption specific surface area (hereinafter, referred to as BET) is 100 to 250 m ²
/ G is used.

Specific examples of the silica include dry-process white carbon, which is generally used as a reinforcing agent.
Examples include wet-process white carbon, colloidal silica, and precipitated silica disclosed in, for example, JP-A-62-62838. Specific products include:
For example, Nipsil VN3 (manufactured by Nippon Silica Co., Ltd., CTA
B 144 m ² / g, BET 210 m ² / g), Ultrasil VN3 (CTAB 165 m ² / Degsa)
g, BET 172 m ² / g), Nipsil AQ (manufactured by Nippon Silica Co., Ltd., CTAB 150 m ² / g, BET 2
27m ² / g), Z1115 (manufactured by Rhodia, CTA)
B 103 m ² / g, BET 112 m ² / g) and the like. These may be used alone or in combination of two or more.

The compounding amount of the silica-containing carbon black and the carbon black and / or silica with respect to the rubber component is 5 to 80 parts, more preferably 10 to 70 parts, of the silica-containing carbon black per 100 parts of the rubber component.
And the total amount of carbon black and / or silica and silica-containing carbon black is from 40 to 100.
Parts, more preferably 45 to 90 parts. If the amount of the silica-containing carbon black is too small, the effect of using the silica-containing carbon black cannot be sufficiently obtained because the amount of the carbon black and / or silica is too large. Means that the rolling resistance of the tire increases. If the total amount of carbon black and / or silica and silica-containing carbon black is too small, the abrasion resistance is low, and if it is too large, the rolling resistance of the tire increases.

The carbon black and / or
The total amount of silica and silica-containing carbon is 40 to 100
Parts, but since the silica-containing carbon is 5 to 80 parts, the compounding amount of carbon black and / or silica may be 0, but the amount of carbon black used is 5 parts or more. It is preferable from the viewpoint of reducing the compounding cost, and the amount of silica used is preferably 5 parts or more from the viewpoint of rolling resistance.

The polymer having an alkylene oxide structure (hereinafter also referred to as AO polymer) used in the present invention is:
It is a component used for lowering the viscosity of the rubber composition and improving processability by being compounded.

The AO polymer is not particularly limited,
It is preferred that the proportion of alkylene oxide (hereinafter also referred to as AO) units in the molecule be 80% or more, more preferably 90% or more and 100% or less. The AO unit is 1
In the case of 00%, water or an alkylene glycol obtained by adding water to AO is used as a starting material, and AO is addition-polymerized to the starting material. Further, an AO polymer having an AO unit of less than 100% refers to a monohydric alcohol (for example, methanol, ethanol or the like) or an alkylene glycol which is not a dihydric alcohol but is obtained by adding water to AO. (E.g., hexamethylenediol, etc.) and other compounds having active hydrogen such as bisphenol A (e.g.
Is added.

As the AO, ethylene oxide,
Propylene oxide and butylene oxide are common, and usually ethylene oxide and propylene oxide are often used.

The molecular weight of the AO polymer is generally from 200 to 100,000, more preferably from 300 to 10,000.
In particular, it is preferably from 400 to 5000 from the viewpoint of bleeding, processability, and ease of dispersion in the rubber composition. If the molecular weight is too small, the AO polymer tends to bleed from the rubber composition, and if it is too large, it is difficult to disperse in the rubber composition because of a high polymer.
As a result, the unvulcanized viscosity of the rubber composition increases, and the processability tends to decrease.

Specific examples of the AO polymer include polyethylene oxide, polypropylene oxide, ethylene oxide-propylene oxide copolymer, and polyethylene glycol. These are generally commercially available and can be easily obtained.

The amount of the AO polymer used is 2 to 20 with respect to the total amount of the silica-containing carbon black and silica.
%, Preferably 3 to 10%. If the amount of the AO polymer used is too small, the viscosity of the rubber composition will not be sufficiently reduced even if the AO polymer is blended, and the processability will not be sufficiently improved.
On the other hand, if the amount is too large, the effect is small for the compounding amount,
Become uneconomical.

When the AO polymer and the silica-containing carbon black and the mixture of the AO polymer and silica are mixed separately, the amount of the AO polymer used is as follows:
2 to 10%, more preferably 3 to 8%, based on silica-containing carbon black, 4 to 20%, more preferably 6 to 20%, based on silica.
-16%, and the total amount thereof is an amount that satisfies the usage amount of the AO polymer with respect to the total amount of the silica-containing carbon black and silica. When the use amount of the AO polymer to the silica-containing carbon black and silica is too small, the viscosity of the rubber composition becomes high, and
If the workability is deteriorated and the amount is too large, the effect of the proportion of the compounding amount is small and the cost becomes uneconomical.

The use ratio of the AO polymer to the silica-containing carbon black and the silica is such that the use ratio of the AO polymer to the silica-containing carbon black is about 1/1 / the of the use ratio of the AO polymer to the silica.
It should be used in consideration of 2. More specifically, when a mixture of 100 parts of silica-containing carbon black and 100 parts of silica is mixed with 15 parts of an AO polymer, 5 parts of the AO polymer are used for the silica-containing carbon black.
0 parts may be handled for silica.

The rubber composition for tires of the present invention comprising the rubber component, silica-containing carbon black, carbon black and / or silica used as required, and AO polymer is further compounded with a silane coupling agent. By doing so, it is possible to improve wear resistance, rolling resistance, and the like.

Specific examples of the silane coupling agent include, for example, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, and β- (3,4 epoxycyclohexyl) ethyltrimethoxy. Silane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane Γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyl Trimethoxysilane, N-
β (aminoethyl) γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-
Aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, bis- (3- [triethoxysilyl]-
Propyl) -tetrasulfene and the like. These may be used alone or in combination of two or more. Of these, bis- (3- [triethoxysilyl] -propyl) -tetrasulfene is preferred.

The amount of the silane coupling agent used is 3 to 10%, and more preferably 4 to 8%, based on the total amount of the silica-containing carbon black and silica. If the use of the silane coupling agent for silica-containing carbon black and silica is too small, the performance such as abrasion resistance and rolling resistance tends to decrease. Does not mean
The cost tends to increase.

When the silane coupling agent and the mixture of the silica-containing carbon black and the silica are mixed without separately mixing the silane coupling agent and the silica-containing carbon black and the silane coupling agent and the silica separately, The use ratio of the silane coupling agent to silica-containing carbon black may be about 1/2 of the use ratio of the silane coupling agent to silica.

The composition of the present invention may contain, in addition to the above-mentioned components, components and additives generally used for the production of rubber compositions for tires, if necessary, in the amounts and amounts usually used. . Specific examples of the components and additives include, for example, process oils (paraffinic process oils, naphthenic process oils, aromatic process oils), vulcanizing agents (sulfur, sulfur chloride compounds, organic sulfur compounds, etc.), vulcanization Accelerators (guadinin-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, thiuram-based, dithiocarbamate-based, and zandate-based compounds), crosslinking agents (organic peroxide compounds, Radical generators such as azo compounds, oxime compounds, nitroso compounds, polyamine compounds, etc., reinforcing agents (high styrene resin, phenol-
Formaldehyde resin), antioxidants or antioxidants (diphenylamine-based, p-phenylenediamine-based amine derivatives, quinoline derivatives, hydroquinone derivatives, monophenols, diphenols, thiobisphenols, hindered phenols, Phosphate esters), wax, stearic acid, zinc oxide, softener, filler, plasticizer and the like.

When the composition of the present invention is used to produce a pneumatic tire, it can be used for producing any pneumatic tire regardless of whether it is for a two-wheeled vehicle, a passenger vehicle, or a heavy-duty vehicle. .

The components of the pneumatic tire using the composition of the present invention include, but are not limited to, cap treads, base treads, belt coated rubbers, case coated rubbers, sidewalls, inner liners, chafers, bead apex, and the like. However, it is preferably used for a cap tread, a base tread, a belt-covered rubber, and a side wall, and more preferably a cap tread, a base tread, and a side wall, from the viewpoints of low fuel consumption and improvement in workability.

[0039]

EXAMPLES Next, the composition of the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. The raw materials used in the examples and comparative examples are shown below.

[Raw materials] NR: General RSS # 3 grade SBR: NS116 silica-containing carbon black manufactured by Zeon Corporation: CRX manufactured by Cabot
2000 (4.7 silica on N234 carbon black)
%, DBP 113 cc / 100 g, CDBP Oil absorption 102 cc / 100 g Silica: Ultrasil VN3 carbon black manufactured by Degussa Co., Ltd. Showa Black N351 manufactured by Showa Cabot Co., Ltd. Silane coupling agent: Si69 (bis (3- (tri Ethoxysilyl) propyl) tetrasulfide) polyethylene glycol: PE manufactured by Sanyo Chemical Industries, Ltd.
G4000 (molecular weight 4000) Aromatic oil: Diana Process PS32 manufactured by Idemitsu Kosan Co., Ltd. Antioxidant: Ozonone 6C manufactured by Seiko Chemical Co., Ltd. Wax: Sannoc wax stearic acid manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Co., Ltd. Paulownia Zinc oxide: Two types of zinc oxide manufactured by Mitsui Kinzoku Kogyo Co., Ltd. Sulfur: Powdered sulfur manufactured by Karuizawa Sulfur Co., Ltd. NS: Oxie Shinko Chemical Industry Co., Ltd. Noxeller NS

Examples 1 to 3 and Comparative Examples 1 to 5 The main components shown in Table 1 were mixed in the amounts shown in Table 1, and 2 parts of an antioxidant, 1 part of wax, 2 parts of stearic acid and 3 parts of zinc oxide were added. Parts and 5 parts of an aromatic oil were kneaded with a Banbury at about 150 ° C. for 5 minutes. 1.7 parts of sulfur and 1 part of a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded with a biaxial open roll at 80 ° C. for 5 minutes to produce a rubber composition for a tire tread.

The Mooney viscosity of the obtained rubber composition for a tire tread was measured. The composition was vulcanized at 160 ° C. for 18 minutes to obtain a vulcanized rubber, and the abrasion resistance was evaluated. Further, a tread portion of a tire is formed by using the rubber composition for a tire tread,
Then, vulcanization was performed under the conditions of 19.6 × 10 ⁶ Pa (20 kgf / cm ² ) to produce a 185 / 65R14 size passenger car tire, and the loss tangent and rolling resistance were evaluated.

Table 1 shows the results.

(Mooney Viscosity) The Mooney viscosity of an unvulcanized tire tread rubber composition was measured at 130 ° C. in accordance with JIS 6300. The results are shown by an index with Comparative Example 1 being 100. The larger the number, the lower the viscosity and the better the processability.

(Abrasion resistance) A vulcanized rubber was produced from a rubber composition for a tire tread, and a surface rotation speed of 50 m / min and a sand falling amount of 15 g / m were measured using a Lambourn abrasion tester (manufactured by Iwamoto Seisakusho KK) Min, slip rate 30%, applied load 2.5k
A g wear test was performed. The results are shown as indices with Comparative Example 1 being 100. The larger the index, the better the wear resistance.

(Loss Tangent (Viscoelasticity Test)) Using the rubber composition for a tire tread as a tread, at 165 ° C. for 18 minutes,
Vulcanization was performed under the conditions of 1.96 × 10 ⁶ Pa (20 kgf / cm ² ) to produce 185 / 65R14 size passenger car tires. A test piece was prepared from the tread of the obtained tire, and was subjected to a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. at 60 ° C. under the conditions of a frequency of 10 Hz and a dynamic strain of 1.0%.
Loss tangent (tan δ) was measured. The smaller the numerical value is, the lower the tan δ is, the better the performance is, which indicates that the fuel consumption can be reduced.

(Rolling Resistance) Using a tire manufactured in the same manner as in the case of loss tangent, a drum-type rolling resistance tester manufactured by Kobe Steel Ltd. was used at a speed of 80 km / h, a load of 3.4 kN and an internal pressure of 200 kPa. After running, the rolling resistance was measured. The results are shown by an index with Comparative Example 1 being 100. The larger the index, the lower the rolling resistance and the better the rolling resistance.

[0048]

[Table 1]

Examples 4 to 6 and Comparative Examples 6 to 14 The main components shown in Table 2 were blended in the amounts shown in Table 2, and 2 parts of antioxidant, 1 part of wax, 2 parts of stearic acid and 3 parts of zinc oxide were added. About 15 parts by weight of Banbury.
Kneaded at 0 ° C. for 5 minutes. 1 part of sulfur was added to the obtained kneaded material,
1.5 parts of a vulcanization accelerator were added and kneaded at 80 ° C. for 5 minutes with a biaxial open roll to produce a rubber composition for a tire tread.

The Mooney viscosity of the obtained rubber composition for tire tread was measured. The composition was vulcanized at 150 ° C. for 45 minutes to obtain a vulcanized rubber, and the abrasion resistance was evaluated. Further, a tread portion of a tire is formed by using the rubber composition for a tire tread,
Vulcanization was performed under the conditions of 1.96 × 10 ⁶ Pa (20 kgf / cm ² ) to produce 11R22.5 size heavy-duty vehicle tires, and the loss tangent and rolling resistance were evaluated.

Table 2 shows the results.

(Mooney viscosity) The Mooney viscosity of an unvulcanized tire tread rubber composition was measured at 130 ° C according to JIS 6300. The results are shown by an index with Comparative Example 6 being 100. The larger the number, the lower the viscosity and the better the processability.

(Abrasion resistance) A vulcanized rubber was produced from a rubber composition for a tire tread, and the surface rotation speed was 50 m / min and the sandfall amount was 15 g / m using a Lambourn abrasion tester (manufactured by Iwamoto Seisakusho KK). Min, slip rate 30%, applied load 5.0k
A g wear test was performed. The results were shown as indices with Comparative Example 6 being 100. The larger the index, the better the wear resistance.

(Loss Tangent (Viscoelasticity Test)) A rubber composition for a tire tread was used as a tread at 150 ° C. for 45 minutes.
Vulcanization was performed under the conditions of 1.96 × 10 ⁶ Pa (20 kgf / cm ² ) to produce 11R22.5 truck tires. A test piece was prepared from the tread of the obtained tire, and a loss tangent (tan δ) at 60 ° C. was measured with a viscoelastic spectrometer manufactured by Iwamoto Seisakusho under the conditions of a frequency of 10 Hz and a dynamic strain of 1.0%. The smaller the numerical value is, t
It has low an δ and good performance, indicating that fuel economy can be reduced.

(Rolling Resistance) Using a tire manufactured in the same manner as in the case of the loss tangent, a drum-type rolling resistance tester manufactured by Kobe Steel Ltd. was used at a speed of 80 km / h and a load of 3
The rolling resistance was measured while running at 0 kN and an internal pressure of 800 kPa. The index is shown as an index with Comparative Example 6 being 100. The larger the index, the lower the rolling resistance and the better the index.

[0056]

[Table 2]

From the results shown in Tables 1 and 2, it can be seen that the addition of the silica-containing carbon black can balance the performance between the wear resistance and the rolling resistance, but the workability is poor. However, it is understood that the processability can be improved by further adding an appropriate amount of polyethylene glycol.

[0058]

When the composition of the present invention is used particularly for a tire tread, a pneumatic tire having low fuel consumption, good abrasion resistance and good workability can be produced.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view showing a state where carbon black and silica are three-dimensionally mixed in one particle.

[Explanation of symbols]

 1 Carbon black part 2 Silica part

Continued on the front page F-term (reference) 4J002 AC001 AC011 AC031 AC061 AC071 AC081 AC091 AC141 BB151 BB181 BB241 BC051 BD121 BL011 CH022 CK021 CP031 DA036 DA038 DJ017 DJ018 FB097 FB098 FB107 FB108 FB117 FB138 FB137 138

Claims (3)

[Claims] 1. A rubber component comprising 100 parts by weight of a rubber component and 5 to 80 parts by weight of carbon black containing silica and carbon black and / or silica, containing carbon black containing silica and carbon black and / or silica. And the polymer having an alkylene oxide structure is blended in an amount of 2 to 20% by weight based on the total amount of the silica-containing carbon black and silica. Rubber composition for tires. 2. The tire rubber composition according to claim 1, wherein the silane coupling agent is contained in an amount of 3 to 10% by weight based on the total amount of the silica-containing carbon black and silica. 3. A pneumatic tire using the rubber composition for a tire according to claim 1 in a tire tread.