JP6965980B1 - Rubber composition for tires - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a tire which improves fracture resistance without deteriorating low heat generation. SOLUTION: In 100 parts by mass of diene rubber containing 80% by mass or more of natural rubber, 30 to 60 parts by mass of carbon black, 1.0 to 10 parts by mass of maleic acid-modified rosin resin, according to the following general formula (1). It is characterized by blending 0.5 to 3.0 parts by mass of the represented hydrazide compound. (In the formula, R1 and R2 represent alkyl groups having 1 to 18 carbon atoms independently of each other.) [Selection diagram] None.

Description

The present invention relates to a rubber composition for a tire that has both fracture resistance and low heat generation.

For tires for construction vehicles such as dump trucks, fracture resistance such as chipping resistance, cut resistance, and crack growth resistance is important when traveling on rough roads. In order to improve the fracture resistance, a method is used in which a rubber composition for a tire is blended with a resin to achieve both rubber hardness and elongation at a high level. On the other hand, in recent years, the tire size of dump trucks has been increasing due to the improvement of transportation efficiency, and along with this, the heat generation during running has become an important index. However, in general, the addition of a resin to a rubber composition for a tire leads to deterioration of heat generation, so that both fracture resistance and low heat generation are problems.

Patent Document 1 describes in a rubber kneading step before adding a vulcanizing agent, 0.1 to 5 parts by weight of a specific hydrazide compound and 0.2 to 5 parts by weight of zinc oxide with respect to 100 parts by weight of a rubber component containing natural rubber. A method for producing a rubber composition, which comprises adding parts by weight and carbon black at the same time and kneading at a maximum temperature of 130 ° C. to 170 ° C., is disclosed, and the obtained rubber composition has resistance to resistance. It is described that it has destructiveness and tear resistance, and improves low heat generation. However, the rubber composition described in Patent Document 1 does not always have sufficient fracture resistance, and it has been difficult to achieve both the fracture resistance and low heat generation required for tires for construction vehicles at a high level. ..

Japanese Patent No. 4541475

An object of the present invention is to provide a rubber composition for a tire that improves fracture resistance without deteriorating low heat generation.

（式中、Ｒ¹，Ｒ²は、互いに独立して炭素数１〜１８のアルキル基を表す。） The rubber composition for a tire of the present invention that achieves the above object has 100 parts by mass of diene rubber containing 80% by mass or more of natural rubber, 30 to 60 parts by mass of carbon black, 10 to 30 parts by mass of silica, and an acid value. 1.0 to 10 parts by mass of maleic acid-modified rosin resin having a softening point of 133 ° C. or higher and 160 ° C. or lower , and 0.5 to 0.5 to hydrazide compound represented by the following general formula (1). It is characterized by blending 3.0 parts by mass.

(In the formula, R ¹ and R ² represent alkyl groups having 1 to 18 carbon atoms independently of each other.)

According to the rubber composition for a tire of the present invention, in the present invention, by blending a specific hydrazide compound and a maleic acid-modified rosin resin in combination, the fracture resistance is improved without deteriorating the low heat generation property. Can be done. This rubber composition for tires can be suitably used for tires for construction vehicles such as dump trucks.
be able to.

The maleic acid-modified rosin resin preferably contains a maleic acid-modified rosin resin having an acid value of 37 KOH mg / g or more and 50 KOH mg / g or less, and can have better fracture resistance . Before Symbol carbon black, the nitrogen adsorption specific surface area may is 60~150m ² / g.

The rubber composition for a tire contains 80% by mass or more of natural rubber in 100% by mass of diene-based rubber. The natural rubber rubber is not particularly limited as long as it is usually used for a rubber composition for a tire. By blending natural rubber, the fracture resistance of the rubber composition for tires can be ensured. As an index of fracture resistance, the higher the dynamic elastic modulus of the rubber composition and the larger the tensile elongation at break, the better the fracture resistance when the tire is made.

The content of the natural rubber is 80% by mass or more, preferably 80 to 100% by mass, more preferably 86 to 100% by mass, and further preferably 92 to 100% by mass in 100% by mass of the diene rubber. If the amount of natural rubber is less than 80% by mass, the elastic modulus and elongation at break are insufficient, and the fracture resistance becomes insufficient.

The diene-based rubber can include other diene-based rubbers other than natural rubber. Examples of other diene-based rubbers include butadiene rubber, styrene butadiene rubber, styrene isoprene rubber, isoprene butadiene rubber, ethylene-propylene-diene copolymer rubber, chloroprene rubber, and acrylonitrile butadiene rubber. These other diene-based rubbers may be modified with one or more functional groups. The type of the functional group is not particularly limited, but for example, an epoxy group, a carboxy group, an amino group, a hydroxy group, an alkoxy group, a silyl group, an alkoxysilyl group, an amide group, an oxysilyl group, a silanol group, an isocyanate group, etc. Examples thereof include an isothiocyanate group, a carbonyl group and an aldehyde group.

The rubber composition for a tire contains 30 to 60 parts by mass of carbon black in 100 parts by mass of diene rubber. Destruction resistance can be ensured by blending carbon black. Carbon black can be blended in an amount of 30 to 60 parts by mass, preferably 33 to 55 parts by mass, and more preferably 36 to 50 parts by mass. If the amount of carbon black is less than 30 parts by mass, the fracture resistance is insufficient. Further, if it exceeds 60 parts by mass, the heat generation may increase. Two or more types of carbon black may be used in combination.

The carbon black is not particularly limited as long as it is usually used for a rubber composition for a tire, particularly a rubber composition for a tire for a construction vehicle. Preferably, the nitrogen adsorption specific surface area is 60 to 150 m ² / g, more preferably 70 to 140 ² / g, and even more preferably 80 to 130 ² / g. If the nitrogen adsorption specific surface area is ^{less than 60 m 2} / g, the fracture resistance may be insufficient. Further, if it exceeds 150 m ² / g, heat generation may increase. The nitrogen adsorption specific surface area of carbon black can be determined in accordance with JIS K6217-2.

The rubber composition for a tire contains 1.0 to 10 parts by mass of a maleic acid-modified rosin resin in 100 parts by mass of a diene-based rubber. By blending a maleic acid-modified rosin resin, both fracture resistance and low heat generation can be achieved. The maleic acid-modified rosin resin can be blended in an amount of 1.0 to 10 parts by mass, preferably 2.0 to 8.0 parts by mass, and more preferably 3.0 to 6.0 parts by mass. If the amount of the maleic acid-modified rosin resin is less than 1.0 part by mass, both fracture resistance and low heat generation cannot be achieved at the same time. Further, if it exceeds 10 parts by mass, the heat generating property becomes rather large.

The maleic acid-modified rosin resin is not particularly limited as long as it is usually used in a rubber composition for a tire. Preferably, it contains a maleic acid-modified rosin resin having an acid value of 50 KOH mg / g or less. Further, a mixture of a maleic acid-modified rosin resin having an acid value of 50 KOH mg / g or less and a maleic acid-modified rosin resin having an acid value of more than 50 KOH mg / g may be used. By containing a maleic acid-modified rosin resin having an acid value of 50 KOH mg / g or less, both fracture resistance and low heat generation can be achieved, and in particular, fracture resistance can be made more excellent. The acid value of the maleic acid-modified rosin resin can be adjusted by the degree of modification of maleic acid. In the present specification, the acid value of the maleic acid-modified rosin resin represents the amount of potassium hydroxide required to neutralize the acid contained in 1 g of the resin in milligrams, and is represented by the potentiometric titration method (JIS K). It can be measured according to 0070: 1992).

The softening point of the maleic acid-modified rosin resin is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and even more preferably 120 ° C. or higher. If the softening point is less than 80 ° C., the resins may melt and agglomerate due to the influence of air temperature, which may adversely affect the handleability. The softening point of the maleic acid-modified rosin resin is preferably 160 ° C. or lower, more preferably 150 ° C. or lower. If the temperature exceeds 160 ° C., the resin component may not be sufficiently dissolved in the rubber component and may become a fracture nucleus, which is not preferable. As the softening point of the maleic acid resin, the softening point defined in JIS K 6220-1: 2001 can be measured by a ring-ball type softening point measuring device.

The glass transition temperature of the maleic acid-modified rosin resin is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, still more preferably 60 ° C. or higher. When the glass transition temperature is less than 40 ° C., the dynamic elastic modulus and the tensile elongation at break are lowered, and the fracture resistance is lowered. The glass transition temperature is preferably 180 ° C. or lower, more preferably 150 ° C. or lower, and even more preferably 120 ° C. or lower. If the temperature exceeds 180 ° C., the heat generation is exacerbated. The glass transition temperature can be set to the midpoint temperature of the transition region by measuring the thermogram by differential scanning calorimetry (DSC) under the heating rate condition of 20 ° C./min.

The weight average molecular weight of the maleic acid-modified rosin resin is preferably 500 to 5000, more preferably 1000 to 4000. By keeping the weight average molecular weight within such a range, the target performance can be obtained. The weight average molecular weight can be determined by gel permeation chromatography (GPC) in terms of standard polystyrene.

As the maleic acid-modified rosin resin, for example, Marquid No. 1 manufactured by Arakawa Chemical Industry Co., Ltd. 1, 2, 5, 6, 8, 31, 32, 33, 34, 382, 3002, etc., Harima Chemicals Harima Mac R-80, T-80, R-100, M-453, M-130A, 135GN, 145P, R-120AH and the like can be mentioned. Among them, Marquid No. manufactured by Arakawa Chemical Industry Co., Ltd. 1 (acid value: 25 KOHmg / g), No. 8 (acid value: 37 KOHmg / g) or the like is preferable.

（式中、Ｒ^１，Ｒ^２は、互いに独立して炭素数１〜１８のアルキル基を表す。） The rubber composition for a tire contains a hydrazide compound represented by the following general formula (1).

(In the formula, R ¹ and R ² represent alkyl groups having 1 to 18 carbon atoms independently of each other.)

In the general formula (1), R ¹ and R ² are alkyl groups having 1 to 18 carbon atoms independently of each other, and are, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-. Butyl, pentyl, hexyl, peptyl, octyl. Nonyl, decyl, undecylic, dodecyl, tridecylic, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl and the like can be mentioned. Further, ^one of R 1 and R ² is preferably methyl.

Examples of the hydrazide compound represented by the general formula (1) include 1-hydroxy-N'-(1-methylethylidene) -2-naphthoic acid hydrazide and 1-hydroshiki-N'-(1-methylpropanol) -2. -Hydrazide naphthoic acid, 1-hydroxy-N'-(1-methylbutylidene) -2-naphthoic acid hydrazide, 1-hydroxy-N'-(1,3-dimethylbutylidene) -2-naphthoic acid hydrazide, 1 -Hydraz-hydroxy-N'-(2-furylmethylene) -2-naphthoic acid hydrazide, 3-hydroxy-N'-(1-methylethylidene) -2-naphthoic acid hydrazide, 3-hydroxy-N'-(1-methyl) Propyridene) -2-naphthoic acid hydrazide, 3-hydroxy-N'-(1-methylbutylidene) -2-naphthoic acid hydrazide, 3-hydroxy-N'-(1,3-dimethylbutylidene) -2- Hydrazide naphthoic acid, 3-hydroxy-N'-(2-furylmethylene) -2-naphthoic acid hydrazide and the like can be mentioned, preferably 1-hydroxy-N'-(1-methylethylidene) -2-naphthoe. Hydrazide acid, 1-hydroshiki-N'-(1-methylpropylidene) -2-naphthoic acid hydrazide, 1-hydroxy-N'-(1,3-dimethylbutylidene) -2-naphthoic acid hydrazide, 1-hydroxy -N'-(2-furylmethylene) -2-naphthoic acid hydrazide, 3-hydroxy-N'-(1-methylethylidene) -2-naphthoic acid hydrazide, 3-hydroxy-N'-(1-methylpropylidene) ) -2-Naphthalic acid hydrazide, 3-hydroxy-N'-(1,3-dimethylbutylidene) -2-naphthoic acid hydrazide, 3-hydroxy-N'-(2-furylmethylene) -2-naphthoic acid hydrazide Is illustrated.

The hydrazide compound represented by the general formula (1) is 0.5 to 3.0 parts by mass, preferably 1.0 to 3.0 parts by mass, more preferably 1. Mix 0 to 2.0 parts by mass. If the amount of the hydrazide compound is less than 0.5 parts by mass, the effect of improving fracture resistance and low heat generation cannot be obtained. If it exceeds 3.0 parts by mass, the workability deteriorates and the desired performance cannot be obtained.

Silica can be further blended in the rubber composition for tires, and the heat generation can be further reduced. The silica may be blended in 100 parts by mass of the diene rubber, preferably 10 to 30 parts by mass, more preferably 12 to 28 parts by mass, and further preferably 15 to 25 parts by mass. Examples of silica include wet silica (hydrous silicic acid), dry silica (silicic anhydride), calcium silicate, aluminum silicate, and the like, and these may be used alone or in combination of two or more. Further, surface-treated silica in which the surface of silica is surface-treated with a silane coupling agent may be used.

The rubber composition for tires preferably contains a silane coupling agent together with silica, and can improve the dispersibility of silica. As the silane coupling agent, a type usually blended with silica can be used. The silane coupling agent may contain preferably 5 to 15% by mass, more preferably 8 to 12% by mass, of the amount of silica.

The rubber composition for a tire may contain a filler other than carbon black and silica. Examples of other fillers include calcium carbonate, magnesium carbonate, talc, clay, mica, alumina, aluminum hydroxide, titanium oxide, and calcium sulfate. These other fillers may be used alone or in combination of two or more.

Rubber compositions for tires are commonly used in rubber compositions for tires such as vulcanization or cross-linking agents, vulcanization accelerators, anti-aging agents, plasticizers, processing aids, liquid polymers, thermosetting resins and the like. Various additives can be blended within a range that does not impair the object of the present invention. Further, such an additive can be kneaded by a general method to form a rubber composition, which can be used for vulcanization or cross-linking. The blending amount of these additives can be a conventional general blending amount as long as it does not contradict the object of the present invention.

The rubber composition for a tire of the present invention is suitable for forming a tire for a construction vehicle. The tire for construction vehicles formed of this rubber composition for tires has excellent fracture resistance such as chipping resistance, cut resistance, and crack growth resistance, and has low heat generation and excellent fuel efficiency. Can be done.

Hereinafter, the present invention will be further described with reference to Examples, but the scope of the present invention is not limited to these Examples.

Sulfur and vulcanization of rubber compositions for tires (Examples 1 to 12, Standard Examples 1 to 2, Comparative Examples 1 to 16) having the compounding agents shown in Table 5 as a common compounding and the compounding shown in Tables 1 to 4 are used. The components excluding the accelerator were kneaded in a 1.7 L closed rubbery mixer for 5 minutes, then discharged from the mixer and cooled to room temperature. This was put into the 1.7 L closed type Banbury mixer described above, and sulfur and a vulcanization accelerator were added and mixed to prepare a rubber composition for a tire. The blending amount of the compounding agent shown in Table 5 is shown in parts by mass with respect to 100 parts by mass of the diene rubber shown in Tables 1 to 4. Using the obtained rubber composition for tires, the dynamic elastic modulus E', tensile elongation at break, and tan δ were evaluated by the following evaluation methods.

Dynamic modulus E'and tan δ
The rubber composition for tires obtained above was press-vulcanized at 148 ° C. for 30 minutes using a predetermined mold to prepare a test piece. Using the obtained test piece, using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho) in accordance with JIS K6394, under the conditions of temperature 20 ° C, frequency 20 Hz, static strain 10%, dynamic strain ± 2%. The dynamic elastic modulus E'at 20 ° C. was measured. The obtained results are "elastic modulus E'(20 ° C.)" as an index in which the value of Standard Example 1 is set to 100 in Tables 1 and 2 and an index in which the value of Standard Example 2 is set to 100 in Tables 3 and 4. Shown in the column. When this index is 105 or more, the dynamic elastic modulus E'is high and the cut resistance is excellent, and when the index of tensile elongation at break described later is 105 or more, it means that the fracture resistance is excellent.

In addition, in accordance with JIS K6394, using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho), the loss tangent tan δ at 60 ° C under the conditions of temperature 60 ° C, frequency 20 Hz, static strain 10%, and dynamic strain ± 2%. Was measured. The obtained results are "tan δ (60 ° C.)" as an index in which the reciprocal of the value of Standard Example 1 is 100 in Tables 1 and 2, and an index in which the reciprocal of the value of Standard Example 2 is 100 in Tables 3 and 4. Shown in the column. When this index is 100 or more, it means that low heat generation is maintained and improved.

Tensile elongation at break The tire rubber composition obtained above was press-vulcanized at 148 ° C. for 30 minutes using a predetermined die to prepare a test piece. From the obtained test piece, a JIS No. 3 dumbbell type test piece was cut out. The tensile elongation at break was measured under the conditions of a temperature of 100 ° C. and a tensile speed of 500 mm / min according to JIS K6251. The obtained results are shown in the column of "elongation at break (100 ° C.)" as an index in which the value of Standard Example 1 is set to 100 in Tables 1 and 2 and an index in which the value of Standard Example 2 is set to 100 in Tables 3 and 4. It was shown to. If this index is 105 or more, the chipping resistance and crack growth resistance are excellent, and if the index of the dynamic elastic modulus E'is 105 or more, the dynamic elastic modulus E'is high and the cut resistance is excellent. means.

・ヒドラジド化合物−２：下記式（３）で表されるヒドラジド化合物、

・ヒドラジド化合物−３：下記式（４）で表されるヒドラジド化合物、

・ヒドラジド化合物−４：アジピン酸ジヒドラジド、大塚化学社製アジピン酸ジヒドラジド（ＡＤＨ）
・ヒドラジド化合物−５：セバシン酸ジヒドラジド、大塚化学社製セバシン酸ジヒドラジド（ＳＤＨ） In Tables 1 to 4, the types of raw materials used are as follows.
・ NR: Natural rubber, RSS # 3
-Carbon black-1: ISAF grade, Cabot Japan show black N220, nitrogen adsorption specific surface area 110 m ² / g
-Carbon black-2: HAF grade, Cabot Japan show black N330, nitrogen adsorption specific surface area 80 m ² / g
-Silica: ULTRASIL VN3GR manufactured by Evonik Industries
-Coupling agent: Si69 manufactured by Evonik Degussa, bis (triethoxysilylpropyl) tetrasulfide / maleic acid-modified rosin-1: maleic acid-modified rosin resin, marquid 382 manufactured by Arakawa Chemical Industry Co., Ltd., acid value; 107 KOHmg / g, softened Point; 108 ° C., glass transition temperature; 57 ° C., weight average molecular weight; 1633
-Maleic acid-modified rosin-2: Maleic acid-modified rosin resin, Marquid No. manufactured by Arakawa Chemical Industries, Ltd. 8, acid value; 37 KOHmg / g, softening point; 133 ° C, glass transition temperature; 82 ° C, weight average molecular weight; 2959
Gum rosin: Chinese gum rosin manufactured by Arakawa Chemical Industry Co., Ltd., acid value: 173 KOHmg / g, softening point: 79.5 ° C, glass transition temperature: 37 ° C, weight average molecular weight: 320
-DCPD resin: Dicyclopentadiene resin manufactured by Arakawa Chemical Industries, Ltd., softening point; 129 ° C, glass transition temperature; 58 ° C, weight average molecular weight; 850
-Hydrazide compound-1: Hydrazide compound represented by the following formula (2), DC-01 manufactured by Otsuka Chemical Co., Ltd.

-Hydrazide compound-2: A hydrazide compound represented by the following formula (3),

-Hydrazide compound-3: A hydrazide compound represented by the following formula (4),

-Hydrazide compound-4: adipic acid dihydrazide, adipic acid dihydrazide (ADH) manufactured by Otsuka Chemical Co., Ltd.
-Hydrazide compound-5: sebacic acid dihydrazide, sebacic acid dihydrazide (SDH) manufactured by Otsuka Chemical Co., Ltd.

Method for producing hydrazide compound-2:
Hydrazide 3-hydroxy-2-naphthoate and 3-methyl-2-pentanone were stirred while heating. After concentrating and cooling the reaction solution, the precipitated crystals were filtered and dried under reduced pressure to obtain hydrazide compound-2 having the structure represented by the above formula (3).

Method for producing hydrazide compound-3:
3-Hydroxy-2-naphthoic acid hydrazide and 3-pentanone were stirred while heating. After concentrating and cooling the reaction solution, the precipitated crystals were filtered and dried under reduced pressure to obtain hydrazide compound-3 having the structure represented by the above formula (3).

In Table 5, the types of raw materials used are as follows.
・ Stearic acid: NOF beads stearic acid ・ Anti-aging agent: Ozonon 6C manufactured by Seiko Kagaku Co., Ltd.
・ Zinc oxide: Zinc oxide 3 types manufactured by Shodo Chemical Industry Co., Ltd. ・ Vulcanization accelerator: Noxeller NS-P manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
-Sulfur: Fine-grained sulfur containing Jinhua Ink oil manufactured by Tsurumi Chemical Industry Co., Ltd. (sulfur content 95.24% by mass)

As is clear from Tables 1 to 4, the rubber compositions for tires of Examples 1 to 12 are excellent in dynamic elastic modulus E'(20 ° C.), tensile elongation at break (100 ° C.), and tan δ (60 ° C.). It was confirmed that it has excellent fracture resistance and low heat generation.

As is clear from Table 1, the rubber composition for tires of Comparative Example 1 did not contain a maleic acid-modified rosin resin, but instead contained gum rosin, so that tensile elongation at break could be sufficiently improved and low heat generation. Is inferior.
Since the rubber composition for a tire of Comparative Example 2 did not contain a maleic acid-modified rosin resin but instead contained a dicyclopentadiene resin (DCPD resin in the table), the dynamic elastic modulus E'was inferior.
Since the rubber compositions for tires of Comparative Examples 3 and 4 do not contain the hydrazide compound represented by the general formula (1), they are inferior in low heat generation.
Since the rubber composition for tires of Comparative Example 5 does not contain a maleic acid-modified rosin resin, it is inferior in dynamic elastic modulus E'and tensile elongation at break.

As is clear from Table 2, the rubber composition for a tire of Comparative Example 6 is inferior in low heat generation because it does not contain the hydrazide compound represented by the general formula (1) but instead contains adipic acid dihydrazide.
The rubber composition for a tire of Comparative Example 7 is inferior in low heat generation because it does not contain the hydrazide compound represented by the general formula (1) but instead contains sebacic acid dihydrazide.
In the rubber composition for tires of Comparative Example 8, since the maleic acid-modified rosin resin exceeds 10 parts by mass, the low heat generation property is rather deteriorated.

As is clear from Table 3, the rubber composition for tires of Comparative Example 9 did not contain a maleic acid-modified rosin resin, but instead contained gum rosin, so that tensile elongation at break could be sufficiently improved and low heat generation. Is inferior.
Since the rubber composition for a tire of Comparative Example 10 did not contain a maleic acid-modified rosin resin but instead contained a dicyclopentadiene resin (DCPD resin in the table), the dynamic elastic modulus E'was inferior.
Since the rubber compositions for tires of Comparative Examples 11 and 12 do not contain the hydrazide compound represented by the general formula (1), they are inferior in low heat generation.

As is clear from Table 4, the rubber composition for a tire of Comparative Example 13 is inferior in low heat generation because it does not contain the hydrazide compound represented by the general formula (1) but instead contains adipic acid dihydrazide.
Since the rubber composition for a tire of Comparative Example 14 did not contain the hydrazide compound represented by the general formula (1) but instead contained sebacic acid dihydrazide, it was inferior in low heat generation.
Since the rubber composition for tires of Comparative Example 15 does not contain a maleic acid-modified rosin resin, it is inferior in dynamic elastic modulus E'and tensile elongation at break.
In the rubber composition for tires of Comparative Example 16, since the maleic acid-modified rosin resin exceeds 10 parts by mass, the low heat generation property is rather deteriorated.

Claims (3)

100 parts by mass of diene rubber containing 80% by mass or more of natural rubber, 30 to 60 parts by mass of carbon black, 10 to 30 parts by mass of silica, acid value of 50 KOHmg / g or less , and softening point of 133 ° C. or more and 160 A rubber for tires, which comprises 1.0 to 10 parts by mass of a maleic acid-modified rosin resin having a temperature of ° C. or lower, and 0.5 to 3.0 parts by mass of a hydrazide compound represented by the following general formula (1). Composition.

(In the formula, R ¹ and R ² represent alkyl groups having 1 to 18 carbon atoms independently of each other.) The rubber composition for a tire according to claim 1, wherein the maleic acid-modified rosin resin contains a maleic acid-modified rosin resin having an acid value of 37 KOH mg / g or more and 50 KOH mg / g or less. The rubber composition for a tire according to claim 1 or 2 , wherein the carbon black has a nitrogen adsorption specific surface area of 60 to 150 m ^{2 / g.}