Rubber composition for tire tread, and tire

Abstract

To provide a rubber composition for a tire tread, which allows a tire to exhibit excellent wear resistance by being used for a tread.SOLUTION: A rubber composition for a tire tread contains a rubber component and carbon black. In the rubber component, the proportion of a modified butadiene rubber is 5 mass% or more and the proportion of an unmodified butadiene rubber is 10 mass% or more. The carbon black has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 130 m2 / g or more, a ratio (CTAB / IA) of the CTAB (m2 / g) to an iodine adsorption (IA) (mg / g) of 0.92 or more and 1.06 or less, and a hydrogen release amount of 3,500 mass ppm or more and 4,800 mass ppm or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a rubber composition for a tire tread and a tire.

Background Art

[0002] Particularly, wear resistance is required for the tread of a tire, and performance improvement has been achieved by optimizing the materials used for manufacturing the tread.

[0003] For example, Patent Document 1 discloses that by using a rubber composition in which a butadiene polymer having a relatively high cis content modified with a predetermined modifier and carbon black having a nitrogen adsorption specific surface area exceeding 100 m 2 / g are combined for the tread, a pneumatic tire having excellent low rolling resistance and wear resistance can be obtained.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the rubber composition described in Patent Document 1 has room for improvement in further enhancing wear resistance.

[0006] Therefore, an object of the present invention is to provide a rubber composition for a tire tread that can exhibit excellent wear resistance in a tire when used for the tread. Another object of the present invention is to provide a tire having excellent wear resistance.

Means for Solving the Problems

[0007] As a result of intensive studies to solve the above problems, the present inventors have found that a rubber composition capable of improving wear resistance can be obtained by using carbon black having predetermined physical properties and using a modified butadiene rubber and an unmodified butadiene rubber in a predetermined amount as rubber components, and thus have completed the present invention.

[0008] The gist configuration of the present invention for solving the above problems is as follows.

[0009] The rubber composition for a tire tread of the present invention contains a rubber component and carbon black, wherein the proportion of the modified butadiene rubber in the rubber component is 5% by mass or more, and the proportion of the unmodified butadiene rubber is 10% by mass or more, the carbon black has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 130 m 2 / g or more, a ratio (CTAB / IA) of the CTAB (m 2 / g) to the iodine adsorption amount (IA) (mg / g) of 0.92 or more and 1.06 or less, and a hydrogen evolution amount of 3500 mass ppm or more and 4800 mass ppm or less, and is characterized by this. Such a rubber composition for a tire tread of the present invention can exhibit excellent wear resistance in a tire when used for a tread.

[0010] In the rubber composition for a tire tread of the present invention, from the viewpoints of cost and workability during rubber kneading, etc., the proportion of the modified butadiene rubber in the rubber component is preferably 30% by mass or less.

[0011] In the rubber composition for a tire tread of the present invention, from the viewpoints of further improving wear resistance and maintaining other performances such as low loss property and processability well, the CTAB of the carbon black is preferably 135 m 2 / g or more and 150 m 2 / g or less.

[0012] In the rubber composition for a tire tread of the present invention, the content of the carbon black is preferably 40 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the rubber component. In this case, the abrasion resistance can be effectively improved, and other properties such as low loss property and processability can be maintained well.

[0013] In the rubber composition for a tire tread of the present invention, it is preferable that the rubber component further contains natural rubber. In this case, the mechanical strength as a rubber article can be increased.

[0014] The tire of the present invention is characterized in that the above-described rubber composition for a tire tread is used for the tread. Such a tire of the present invention is excellent in abrasion resistance.

Effects of the Invention

[0015] According to the present invention, it is possible to provide a rubber composition for a tire tread capable of exhibiting excellent abrasion resistance in a tire when used for a tread. Further, according to the present invention, it is possible to provide a tire excellent in abrasion resistance.

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described. However, these descriptions are for the purpose of exemplifying the present invention and do not limit the present invention in any way.

[0017] (Rubber Composition for Tire Tread) The rubber composition for a tire tread according to an embodiment of the present invention (hereinafter sometimes referred to as "the rubber composition of the present embodiment") contains a rubber component and carbon black. The rubber component requires that the proportion of the modified butadiene rubber is 5% by mass or more and the proportion of the unmodified butadiene rubber is 10% by mass or more. Further, the carbon black used in the present embodiment has, as a first physical property, a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 130 m 2 / g or more, and as the second physical property, the ratio of the CTAB (m 2 / g) to the iodine adsorption amount (IA) (mg / g) (CTAB / IA) is 0.92 or more and 1.06 or less, and as the third physical property, the hydrogen release amount is 3500 mass ppm or more and 4800 mass ppm or less. Note that the carbon black having such physical properties is substantially new.

[0018] <Rubber component> As described above, the rubber composition of this embodiment contains, as an essential rubber component, a modified butadiene rubber (also referred to as modified BR) and an unmodified butadiene rubber (unmodified BR, or simply also referred to as BR). In this embodiment, surprisingly, by using a modified butadiene rubber and an unmodified butadiene rubber as rubber components in a predetermined amount together with carbon black having predetermined physical properties described later, it has been found that the resulting rubber composition can exhibit excellent abrasion resistance. In this regard, the modified butadiene rubber exhibits excellent reinforcement by chemically bonding with carbon black and improves abrasion resistance, while it can deteriorate the filler dispersibility on the micrometer order. This deterioration of the filler dispersibility can act disadvantageously on the abrasion resistance. Therefore, by using the unmodified butadiene rubber in combination, the filler dispersibility is improved, and it is considered that the reinforcement and the filler dispersibility can be compatible in a high dimension, and as a result, excellent abrasion resistance is exhibited. Therefore, in either case where the modified butadiene rubber is used but the unmodified butadiene rubber is not used, and where the unmodified butadiene rubber is used but the modified butadiene rubber is not used, a sufficient effect of improving abrasion resistance cannot be obtained.

[0019] The modified butadiene rubber is a butadiene rubber having one or more functional groups having atoms other than carbon and hydrogen. The modified butadiene rubber may have the above functional groups at the terminal or in the main chain. Further, the modified butadiene rubber can be obtained, for example, by modifying a butadiene rubber (unmodified butadiene rubber) with a modifier.

[0020] Examples of atoms other than carbon and hydrogen include nitrogen atoms, oxygen atoms, sulfur atoms, metalloid atoms, and metal atoms. The functional group preferably has one or more atoms selected from these. Examples of metalloid atoms include boron, silicon, germanium, arsenic, antimony, and tellurium. Among these, one or more atoms selected from boron, silicon, and germanium are more preferable, and silicon is particularly preferable. Examples of metal atoms include tin, titanium, zirconium, bismuth, and aluminum. Among these, one or more atoms selected from tin and titanium are more preferable, and tin is particularly preferable.

[0021] In the rubber composition of the present embodiment, the proportion of the modified butadiene rubber in the rubber component is 5% by mass or more. If the proportion of the modified butadiene rubber in the rubber component is less than 5% by mass, the effect of using it in combination with the unmodified butadiene rubber, and thus the effect of improving the wear resistance, cannot be sufficiently obtained. Further, from the viewpoint of further improving the wear resistance, the proportion of the modified butadiene rubber in the rubber component is preferably 15% by mass or more, and more preferably 20% by mass or more. On the other hand, the upper limit of the proportion of the modified butadiene rubber in the rubber component is not particularly limited, but from the viewpoints of cost and workability during rubber kneading, etc., the proportion of the modified butadiene rubber in the rubber component is preferably 30% by mass or less.

[0022] In the present embodiment, in addition to the modified butadiene rubber described above, unmodified butadiene rubber is used. The unmodified butadiene rubber may be used alone or in combination of two or more.

[0023] In the rubber composition of the present embodiment, the proportion of the unmodified butadiene rubber in the rubber component is 10% by mass or more. If the proportion of the unmodified butadiene rubber in the rubber component is less than 10% by mass, the effect of using it in combination with the modified butadiene rubber, and thus the effect of improving the wear resistance, cannot be sufficiently obtained. Further, the upper limit of the proportion of the unmodified butadiene rubber is not particularly limited, but from the viewpoint of further improving the wear resistance, it is preferably 30% by mass or less, and more preferably 20% by mass or less.

[0024] In the rubber composition of the present embodiment, the proportion of the modified butadiene rubber in the total of the modified butadiene rubber and the unmodified butadiene rubber is preferably 20% by mass or more and 80% by mass or less. In this case, the effect of improving the abrasion resistance peculiar to the present invention can be obtained more sufficiently. From the same viewpoint, the proportion of the modified butadiene rubber in the total of the modified butadiene rubber and the unmodified butadiene rubber is preferably 45% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass or more.

[0025] Further, the rubber composition of the present embodiment preferably further contains natural rubber (NR) in addition to the modified butadiene rubber and the unmodified butadiene rubber described above. In other words, the rubber component used in the present embodiment preferably further contains natural rubber. In this case, the mechanical strength as a rubber article can be increased.

[0026] In the rubber composition of the present embodiment, the proportion of natural rubber in the rubber component is preferably 30% by mass or more and 70% by mass or less. If the proportion of natural rubber in the rubber component is 30% by mass or more, the mechanical strength can be sufficiently increased. Further, if the proportion of natural rubber in the rubber component is 70% by mass or less, the effect of using the modified butadiene rubber and the unmodified butadiene rubber in combination is sufficiently exhibited, and the effect of improving the abrasion resistance peculiar to the present invention can be obtained more reliably.

[0027] In addition, the rubber composition of the present embodiment may or may not contain other rubber components other than the modified butadiene rubber, unmodified butadiene rubber, and natural rubber described above. Examples of other rubber components include isoprene rubber (IR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber, ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), polysulfide rubber, silicone rubber, fluororubber, urethane rubber, and the like. The other rubber components may be used alone or in combination of two or more. However, in the rubber composition of the present embodiment, the proportion of the other rubber components in the rubber components is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, and particularly preferably 0% by mass (that is, does not contain other rubber components).

[0028] <Carbon black> The carbon black used in the present embodiment requires, as the first physical property, that the cetyltrimethylammonium bromide adsorption specific surface area (CTAB) is 130 m 2 / g or more. Since the above carbon black has a CTAB of 130 m 2 / g or more, it can enhance the reinforcing property of the modified butadiene rubber and / or unmodified butadiene rubber mixed as rubber components, and thus contribute to the improvement of abrasion resistance. Further, from the viewpoint of further improving the abrasion resistance, the CTAB of the above carbon black is preferably 135 m 2 / g or more, and from the viewpoint of maintaining other performances such as low loss property and processability well, it is preferably 150 m 2 / g or less. The CTAB of carbon black is measured in accordance with JIS K6217-3. The adjustment of the CTAB of carbon black is not limited, but can be performed, for example, by controlling various conditions such as raw material introduction conditions, air introduction conditions, fuel introduction conditions, and cooling water introduction conditions when manufacturing carbon black.

[0029] The above carbon black preferably has an iodine adsorption amount (IA) of 150 mg / g or less. If the IA of the carbon black is 150 mg / g or less, predetermined activation of the carbon black surface is preferably performed, and the interactivity with the modified butadiene rubber and / or unmodified butadiene rubber mixed as the rubber component can be favorably enhanced. Further, from the viewpoint of favorably maintaining other properties such as low loss property and processability, the IA of the above carbon black is preferably 130 mg / g or more. Note that the IA of the carbon black is measured in accordance with JIS K6217-1. The adjustment of the IA of the carbon black is not limited, but can be performed, for example, by controlling various conditions such as raw material introduction conditions, air introduction conditions, fuel introduction conditions, and cooling water introduction conditions when manufacturing the carbon black.

[0030] Further, as the second physical property, the above carbon black requires that the ratio (CTAB / IA) of the CTAB (m 2 / g) to the iodine adsorption amount (IA) (mg / g) is 0.92 or more and 1.06 or less. If CTAB / IA is less than 0.92, there is a risk of deterioration of wear resistance. Further, if CTAB / IA exceeds 1.06, the processability deteriorates, and thus there is a risk of deterioration of wear resistance. Further, from the viewpoint of further improving the wear resistance, the CTAB / IA of the above carbon black is preferably 0.95 or more and preferably 1.05 or less.

[0031] Furthermore, as the third physical property, the carbon black is required to have a hydrogen release amount of 3,500 ppm by mass or more and 4,800 ppm by mass or less. If the hydrogen release amount is less than 3,500 ppm by mass, the predetermined activation of the carbon black surface and, consequently, the interactivity with the modified butadiene rubber and / or unmodified butadiene rubber mixed as a rubber component will be insufficient, and as a result, the abrasion resistance may deteriorate. Also, if the hydrogen release amount exceeds 4,800 ppm by mass, the abrasion resistance may deteriorate due to excessive hydrogen. Further, from the viewpoint of further improving the abrasion resistance, the hydrogen release amount of the carbon black is preferably 3,700 ppm by mass or more, more preferably 4,500 ppm by mass or less, and even more preferably 4,300 ppm by mass or less. Note that the hydrogen release amount of the carbon black refers to the amount of hydrogen gas released when heated at 2,000°C for 15 minutes in an argon atmosphere and is measured using a hydrogen analyzer. The adjustment of the hydrogen release amount of the carbon black is not limited, but can be performed, for example, by controlling various conditions such as raw material introduction conditions, air introduction conditions, fuel introduction conditions, and cooling water introduction conditions when manufacturing the carbon black.

[0032] The carbon black preferably has a dibutyl phthalate oil absorption (DBP) of 130 cm 3 / 100 g or more and 150 cm 3 / 100 g or less. If the DBP is 130 cm 3 / 100 g or more, the abrasion resistance is further improved, and if it is 150 cm 3 / 100 g or less, the processability can be maintained well.

[0033] The method for producing the carbon black is not particularly limited as long as it can have the desired physical properties. However, it is extremely difficult to adjust the above-described physical properties such as CTAB, IA, and hydrogen release amount in the carbon black individually. The carbon black that can be used in this embodiment can be produced, for example, according to the production conditions in Table 1 of the examples described later.

[0034] In the rubber composition of this embodiment, the content of the carbon black is preferably 40 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the rubber component. If the content of the carbon black is 40 parts by mass or more, the interactivity with the modified butadiene rubber and / or unmodified butadiene rubber mixed as the rubber component is sufficiently increased, and the abrasion resistance can be effectively improved. Further, if the content of the carbon black is 70 parts by mass or less, other properties such as low loss property and processability can be maintained well. From the same viewpoint, the content of the carbon black in the rubber composition is more preferably 45 parts by mass or more and even more preferably 60 parts by mass or less with respect to 100 parts by mass of the rubber component.

[0035] The rubber composition of this embodiment may or may not contain other carbon blacks other than the carbon black having the physical properties described above. Examples of the other carbon blacks include carbon blacks that satisfy only two of the first physical property, the second physical property, and the third physical property described above, carbon blacks that satisfy only one of them, or carbon blacks that satisfy neither of them. However, from the viewpoint of more surely obtaining the effect of improving the abrasion resistance peculiar to the present invention, in the rubber composition of this embodiment, the proportion of the other carbon black in all the carbon blacks is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, and particularly preferably 0% by mass (that is, not containing other carbon blacks).

[0036] <Other components> The rubber composition of this embodiment may contain fillers other than carbon black. Examples of fillers other than carbon black include silica, aluminum hydroxide, clay, alumina, talc, mica, kaolin, glass balloons, glass beads, calcium carbonate, magnesium carbonate, magnesium hydroxide, magnesium oxide, titanium oxide, potassium titanate, barium sulfate, and the like. However, from the viewpoint of more surely obtaining the effect of improving wear resistance peculiar to the present invention, it is preferable that the rubber composition of this embodiment does not contain fillers other than carbon black.

[0037] Further, the rubber composition of this embodiment can appropriately contain compounding agents commonly used in the rubber industry, such as crosslinking agents (vulcanizing agents) such as sulfur, crosslinking accelerators (vulcanization accelerators), process oils, scorch inhibitors, zinc white, stearic acid, etc., within the range not departing from the object of the present invention. Commercially available products can be preferably used as these compounding agents. And the rubber composition can be produced by compounding carbon black and various compounding agents appropriately selected as needed with the rubber component, and performing kneading, heat treatment, extrusion, etc.

[0038] The method for preparing the rubber composition of this embodiment is not particularly limited, and known methods can be used. For example, it can be obtained by kneading components including a predetermined rubber component and carbon black using a kneader such as a Banbury mixer, roll, internal mixer, etc. Further, components other than the crosslinking accelerator and crosslinking agent may be mixed in the non-production (non-pro) stage, and the crosslinking accelerator and crosslinking agent may be compounded and mixed in the production (pro) stage to prepare a rubber composition.

[0039] The rubber composition of this embodiment can be crosslinked or vulcanized. The conditions for crosslinking or vulcanizing the rubber composition can be appropriately adjusted. For example, the temperature can be 120 to 200 °C and the heating time can be 1 minute to 900 minutes.

[0040] (Tire) The tire according to an embodiment of the present invention is characterized in that the rubber composition of the present embodiment is used for the tread. Since the tread of the tire is made of the rubber composition of the present embodiment, it has excellent wear resistance.

[0041] As a method for manufacturing the tire, there is no particular limitation other than using the rubber composition of the present embodiment for the tread, and known methods can be used.

Examples

[0042] Hereinafter, the present invention will be described in more detail with reference to examples. However, these examples are for the purpose of exemplifying the present invention and do not limit the present invention in any way.

[0043] (Production of Carbon Black) Carbon blacks CB1 to CB8 were each produced. The physical properties of each carbon black were controlled by changing various conditions (raw material introduction amount, air introduction amount, temperature, pressure, reaction time, etc.) as shown in Table 1.

[0044]

Table 1

[0045] For the produced CB1 to CB8, in accordance with JIS K6217-3, the cetyltrimethylammonium bromide adsorption specific surface area (CTAB) [m 2 / g] was measured, and in accordance with JIS K6217-1, the iodine adsorption amount (IA) [mg / g] was measured. Further, for the produced CB1 to CB8, using a hydrogen analyzer (manufactured by HORIBA, "EMGA"), the amount of hydrogen gas released (hydrogen release amount) when heated at 2000 °C for 15 minutes in an argon atmosphere was measured. The results are shown in Table 2 together with the calculated values of CTAB / IA.

[0046]

Table 2

[0047] (Preparation of Modified Butadiene Rubber (HMI-BR)) Into a dried and nitrogen-substituted pressure-resistant glass container of about 900 mL, 283 g of cyclohexane, 50 g of 1,3-butadiene, 0.0057 mmol of 2,2-ditetrahydrofurylpropane, and 0.513 mmol of hexamethyleneimine (HMI-BR) were added. After further adding 0.57 mmol of n-butyllithium (BuLi), polymerization was carried out in a 50 °C warm water bath equipped with a stirrer for 4.5 hours. The polymerization conversion rate at this time was almost 100%. Next, 0.100 mmol of tin tetrachloride was quickly added to this polymerization reaction system as a modifier (coupling agent), and the mixture was further stirred at 50 °C for 30 minutes to carry out a modification reaction. Then, 0.5 mL of an isopropanol solution of 2,6-di-t-butyl-p-cresol (BHT) (BHT concentration: 5% by mass) was added to the polymerization reaction system to stop the reaction, and it was further dried according to a conventional method to obtain a modified butadiene rubber (HMI-BR) having tin atoms. Regarding the obtained HMI-BR, 1 When the vinyl bond amount of the butadiene part was measured from the integration ratio of the 1H-NMR spectrum, it was 14%. When the glass transition temperature (Tg) was determined from the inflection point of the DSC curve, it was -95 °C. When the coupling rate was determined from the ratio of the peak area on the highest molecular weight side to the total area of the molecular weight distribution curve by gel permeation chromatography (GPC), it was 65%.

[0048] (Preparation of Rubber Composition) Next, a rubber composition was prepared by thoroughly kneading according to the formulation shown in Table 3. Using the obtained rubber composition, evaluation of abrasion resistance was carried out according to the following procedure.

[0049] <Abrasion Resistance (Lab Test)> Based on the amount of carbon gel and filler dispersibility, which are said to have a high correlation with abrasion resistance, the abrasion resistance (lab test) of each example was evaluated by index.

[0050] (1) Calculation of the Amount of Carbon Gel The unvulcanized rubber composition prepared in each example was cut into small pieces to obtain test pieces, and the mass (M0) was measured. After immersing these test pieces in tetrahydrofuran for 48 hours, they were filtered and dried with a filter, and the mass (M1) of the residue was measured. Then, the "carbon gel amount" in each example was calculated by the following formula. The larger the carbon gel amount, the better the reinforcing property, and the higher the wear resistance effect is considered to be. Carbon gel amount ={(M1)-(M0)×(C1÷C0)} / {(M0)×(C2÷C0)} M0: Mass of the test piece (before immersion) M1: Mass of the residue C0: Total number of parts of all ingredients in the rubber composition C1: Sum of the number of parts of carbon black, zinc oxide and sulfur in the rubber composition C2: Sum of the number of parts of rubber components in the rubber composition

[0051] (2) Measurement of filler dispersibility Separately from the above, the rubber composition prepared in each example was vulcanized at 145 °C for 33 minutes to obtain a vulcanized rubber. For the obtained vulcanized rubber, the Y value of the RCB method was measured using a Dispergrader (manufactured by TECH PRO, USA). The larger this value, the better the filler dispersibility, and the higher the wear resistance effect is considered to be.

[0052] (3) Evaluation of wear resistance (laboratory test) Using the carbon gel amount and filler dispersibility calculated above, the wear resistance (laboratory test) in each example was evaluated by an index. The results are shown in Table 3. Since good wear resistance can be obtained when the reinforcing property and filler dispersibility are improved respectively, the larger the index value, the better the wear resistance.

[0053] <Wear resistance (field test)> In Example 1, Comparative Example 1, and Comparative Example 2, the rubber compositions prepared were used for the tread member, and were vulcanized as appropriate to produce pneumatic tires for trucks and buses with a size of 275 / 80R22.5. The obtained tires were mounted on the driving wheels of the trucks, and after traveling on public roads for 14,000 km or more, the wear amount was measured from the change in the main groove depth of the tires. In other Examples and Comparative Examples, predictions were made based on the measurement results of Example 1, Comparative Example 1, and Comparative Example 2 and the evaluation results of abrasion resistance by the laboratory tests of each example. Then, with the reciprocal of the wear amount of Comparative Example 6 set to 100, the abrasion resistance of each example was evaluated exponentially. The results are shown in Table 3. The larger the index value, the better the abrasion resistance.

[0054]

Table 3

[0055] *1 NR: TSR♯20 *2 Modified BR: Prepared modified butadiene rubber (HMI - BR) *3 Unmodified BR: Manufactured by Ube Industries, Ltd., "UBEPOL BR150L" *4 Vulcanization accelerator CZ: N - cyclohexyl - 2 - benzothiazylsulfenamide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Nocceler CZ" *5 Predicted value from the evaluation result of abrasion resistance by laboratory test

[0056] From Tables 1 to 3, it can be seen that the rubber compositions of the Examples according to the present invention have better evaluation results of abrasion resistance by both laboratory tests and field tests than the rubber compositions of the Comparative Examples.

Industrial Applicability

[0057] According to the present invention, it is possible to provide a rubber composition for tire treads that can exhibit excellent abrasion resistance in tires when used for the tread. Further, according to the present invention, it is possible to provide a tire having excellent abrasion resistance.

Claims

1. containing a rubber component and carbon black, the rubber component has a modified butadiene rubber ratio of 5% by mass or more and an unmodified butadiene rubber ratio of 10% by mass or more, the carbon black has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 130 m ２ / g or more, and the ratio of the CTAB (m ２ / g) to the iodine adsorption amount (IA) (mg / g) (CTAB / IA) is 0.92 or more and 1.06 or less, and the hydrogen release amount, which is the amount of hydrogen gas released when heated at 2000 °C for 15 minutes in an argon atmosphere, is 3500 mass ppm or more and 4800 mass ppm or less, the content of the carbon black is 40 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the rubber component, A rubber composition for a tire tread, characterized by the above.

2. The rubber composition for a tire tread according to claim 1, wherein the ratio of the modified butadiene rubber in the rubber component is 30% by mass or less.

3. The CTAB of the carbon black is 135 m ２ / g or more and 150 m ２ / g or less. The rubber composition for a tire tread according to claim 1 or 2.

4. The rubber composition for a tire tread according to any one of claims 1 to 3, wherein the rubber component further contains natural rubber.

5. A tire, characterized in that the rubber composition for a tire tread according to any one of claims 1 to 4 is used for the tread.

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