JPH07165991A - Rubber composition, its production and tire using the same - Google Patents

Abstract

PURPOSE:To obtain a rubber composition capable of being vulcanized to show a good viscoelastic property, having a good grip and wear resistant property and a low rolling resistance, suitable for tire, consisting of a rubber type copolymer, a vulcanization agent, a loading agent containing a silica and a specific two functional coupling agent. CONSTITUTION:A rubber composition contains a rubber type copolymer (preferably containing 25wt.% or more of a styrene-butadiene copolymer having a styrene component of 20-50%, prepared by an emulsion or solution polymerization), a vulcanization agent, a loading agent containing preferably 15-60wt. pt. of a silica per 100wt. pt. of the rubber type copolymer, and a coupling agent having at least two functionalities capable of reacting with the silica and the rubber type copolymer [preferably a silane coupling agent such as bis-(triethoxy- silylpropyl)-tetrasulfide, etc].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition, particularly a vulcanizable rubber composition such as a rubber composition for tire tread and a tire using the rubber composition.

[0002]

BACKGROUND OF THE INVENTION It is well known that it is desirable to reduce the rolling resistance of automobile tires in order to reduce fuel consumption, but it is common practice to reduce rolling resistance. With a rubber composition having such a composition, at least one of tire grip and abrasion resistance is reduced.

Conventional rubber compositions for reducing rolling resistance of tires include treads using carbon black having a relatively small surface area as a filler and a polymer having a relatively low glass transition temperature. There are rubber compositions having a reduced amount of carbon black in the composition.
However, such a rubber composition causes undesired reduction of the wet grip of the tire and is not satisfactory.

On the other hand, in a tread of a tire, in addition to rolling resistance and abrasion resistance, grip under wet conditions is one of important characteristics. The present invention has been made in view of such circumstances, and an object thereof is to have well-balanced characteristics as a whole, particularly other characteristics such as wet grip and abrasion resistance. It is intended to provide a rubber composition for a tire tread and a tire in which rolling resistance is improved, that is, reduced without sacrificing.

[0005]

The present inventors have found that compounding silica as a filler together with a coupling agent in a tire tread composition brings about a preferable effect on the tire properties, and the present invention has been completed. Came to. That is, the rubber composition of the present invention is a vulcanizable rubber composition containing a rubber-based polymer, a vulcanizing agent, a filler, and a coupling agent, wherein the filler contains silica, and the coupling agent Is at least bifunctional capable of reacting with the silica and the rubber-based polymer.

The method for producing the rubber composition of the present invention is
In the method for producing a vulcanizable rubber composition obtained by mechanically mixing a rubber polymer, a vulcanizing agent, a filler, and a coupling agent, the filler contains silica, and the coupling agent is At least bifunctionality capable of reacting with the silica and the rubber-based polymer, and the mixing step is performed at 130 ° C. or less.

Furthermore, the tire of the present invention is characterized in that the rubber composition of the present invention constitutes a tread. The rubber-based polymer used in the present invention may be a polymer suitably used for the tire tread or any other part of the tire where the property of low rolling resistance is useful, for example, a polymer suitably used for the undertread or the sidewall. A butadiene copolymer (hereinafter referred to as SBR) is preferably at least 25% by weight, particularly preferably 50% by weight or more, and all components of the rubber-based polymer may be SBR. The SBR may be any of solution-polymerized styrene-butadiene copolymer (hereinafter, referred to as solution-polymerized SBR) and emulsion-polymerized styrene-butadiene copolymer (hereinafter, referred to as emulsion-polymerized SBR), but emulsion-polymerized SB
R is preferred. The styrene content of SBR is 20
-50%, especially 30-45% is preferable.

When the rubber-based polymer is composed of a mixture of SBR and another rubber component, for example, polybutadiene homopolymer, vinyl polybutadiene, or a mixture thereof may be blended as the other rubber component. As the silica, 60 to 300 m ² / g, particularly 80 to 250 m ²
It is preferred to have a nitrogen surface area of / g and it is preferred to use precipitated silica. Silica is a rubber-based polymer 10
The content is preferably 15 to 160 parts by weight per 0 parts by weight, and particularly 30 per 100 parts by weight of the rubber polymer.
˜120 parts by weight, for example, 30 to 80 parts by weight is preferable.

Silica may be blended as a simple substance separately from the coupling agent, or may be blended as silica (hereinafter referred to as "coupled silica") which has been coupled by coupling with the coupling agent in advance. Coupled silica is one treated with a coupling agent before compounding silica into a rubber composition. For example, after physically mixing silica and the coupling agent at ambient temperature, the temperature of the mixture is raised. Then, it is obtained by promoting the coupling reaction.

As the coupling agent, at least a bifunctional one capable of reacting with silica and a rubber polymer is used. Specifically, a silane coupling agent or zirconate is used. For example, when the vulcanizing agent is sulfur, bis (3-triethoxy-silylpropyl)-
Tetrasulfide or mercaptopropyltriethoxysilane is preferably used. In these coupling agents, the alkoxy moiety reacts and bonds with silica in the coupling reaction, and the sulfide moiety reacts with the rubber-based polymer in the vulcanization reaction. In addition to the coupling agent, for example, vinylsilane such as vinyltriethoxysilane, thiocyanatotriethoxysilane such as thiocyanato-propyl-triethoxysilane, or zirconium such as zirconium dineoalkanato di (3-mercapto) propionate-0. An acid salt coupling agent is used.

The content of the coupling agent is preferably 2 to 20% by weight, for example, 2 to 18.5% by weight, and particularly preferably 5 to 15% by weight, based on the silica content. The filler may be silica alone or coupled silica alone, but other fillers may be mixed if necessary. In particular, it is preferable to mix carbon black in order to improve abrasion resistance and color the composition.

When carbon black and silica are mixed and mixed as a filler, the total content of the filler in the composition is preferably 40 to 160 parts by weight with respect to 100 parts by weight of rubber. It is preferable to contain at least 3 parts by weight. It is preferable to further add oil to the rubber composition of the present invention. As oil,
Aromatic oils are preferably used. As the aromatic oil, conventionally known ones can be used, and it is particularly preferable to use an aromatic oil having a specific gravity of 0.95 to 1.0. The amount of the oil blended is preferably at least 40 parts by weight, particularly preferably at least 60 parts by weight, based on 100 parts by weight of the rubber-based polymer, and a preferable range is 60 to 180 parts by weight, particularly 80 to 150 parts by weight. Is.

When the rubber is an oil-extended rubber, the ratio of the non-oil component listed here is a numerical value relative to the content of the rubber-based polymer alone excluding the extender oil. References to the proportion of oil contained are numerical values for the total oil content, ie the sum of the amount of extender oil used in the oil-extended rubber and the amount of oil added alone as an additive.

The vulcanizing agent is preferably sulfur or a sulfur-containing compound, but any other suitable vulcanizing agent, such as
Phenolic resins or peroxides can also be used. The vulcanizing agent may be added to the composition at the end of the mixing step after mechanically mixing the other components in the initial stage, and is preferably added in the subsequent mixing step. In the rubber composition of the present invention, in addition to the above components, additives usually used in the rubber industry, for example,
A vulcanization accelerator, an activator, a bulking agent and an antioxidant may be blended as necessary.

The rubber composition of the present invention is obtained by blending the above components and mechanically mixing them. Since the rubber composition of the present invention contains silica as a filler,
It is possible to mix at temperatures below those normally required. For example, a typical tread rubber composition is mixed at about 160 ° C., but a composition of the present invention is mixed at about 1 ° C.
Mixing can be satisfactory at 25 ° C. Mechanical mixing of the composition in the present invention may be carried out at a general mixing temperature, but it is usually carried out while maintaining the temperature of the composition at 130 ° C or lower. For example, it can be carried out at a temperature of about 100 ° C. or lower, but 100 ° C. to 120 ° C. or 12
It is preferable to mix at 5 ° C.

Here, the mechanical mixing of the composition is such that, when coupled silica is used as a filler, the rubber-based polymer, carbon black and coupled silica are first mixed in a single step, and then oil, Then add an activator,
It is carried out by adding a treating agent and a protective agent such as an antiaging agent and an ultraviolet protective agent, and finally adding an accelerator. The discharge temperature from the blender is preferably about 110 ° C to 120 ° C or 125 ° C as described above.

On the other hand, when the silica and the coupling agent are blended separately, mechanical mixing is performed in a two-step operation.
In the first stage, a rubber polymer, silica, a coupling agent and carbon black are mixed, and then an oil and an activator, a processing aid and a protective agent are added. The discharge temperature in the first stage is preferably about 125 ° C to 130 ° C.

In the second stage, vulcanizing agents and accelerators are added and the discharge temperature is lower than in the first stage, for example 105.
° C is applied. When silica and the coupling agent are blended separately, the coupling of the coupling agent and silica is performed during the mechanical mixing stage and / or the vulcanization stage.
On the other hand, the reaction of the polymer with the coupling agent does not take place in the mechanical mixing stage, which is carried out at low temperatures, but usually takes place during the vulcanization stage when the composition is heated to the vulcanization temperature.

[0019]

EXAMPLES Examples of the present invention will be described below.
Generally, in order to demonstrate the rolling resistance and grip properties of a rubber composition for a tire tread, it is common to subject the composition to a viscoelasticity test under laboratory conditions and predict the tire properties from the hysteresis properties that appear in this test. Has been done. This test causes the tread composition to undergo a dynamic deformation that changes in the form of a sine wave under shear, tension or compression at a controlled temperature. It is well known that the wet grip and rolling resistance are explained from the numerical values of the loss modulus and the loss compliance at typical temperatures of 0 ° C and 50 ° C. For example, in order to obtain a high wet grip, it is desirable that at least one of loss modulus and loss compliance at 0 ° C is high, and at least one of loss modulus and loss compliance at 50 ° C is required to reduce rolling resistance. Is desired to be low.

The rubber composition of this example was evaluated by the following viscoelasticity test. Pre-tension 10%, dynamic strain 0.
The complex modulus (E ^* ) at each temperature of 0 ° C. and 50 ° C. under the condition of 5% (double strain amplitude) and frequency of 10 Hz,
The dynamic modulus (E ₁ ), loss modulus (E ₂ ), loss tangent (TD) = tan δ (E ₂ / E ₁ ), loss compliance (LC) = E ₂ / (E ^* ) ² were measured. Further, the abrasion test was conducted according to DIN535616.

Examples 1 to 3 and Comparative Examples 1 to 3 Each of the components shown in Table 1 was blended to prepare rubber compositions of Examples 1 to 3 in which coupled silica was blended as a filler. Each component was prepared using a two-step mixing procedure.
In the first stage, the composition was mixed in a 2 liter laboratory internal mixer to a discharge temperature of 125 ° C. The mixing time was 5.5 minutes. In the second stage, the mixing was completed on two experimental roll mills at about 50 ° C. for about 5 minutes and the addition of sulfur and accelerator.

Further, in each of the examples, an equal amount of carbon black was blended in place of the coupled silica, and Comparative Example 1
The rubber compositions of ~ 3 were prepared. In Table 1, SBR
(A) means a solution-polymerized SBR having a styrene content of 15%, and SBR (B) means oil-extended with 37.5 parts by weight of an aromatic oil per 100 parts by weight of a solution-polymerized SBR having a styrene content of 30%. Show things. SBR1712 is emulsion-polymerized SBR100 having a styrene content of 23.5%.
The oil-extended product is shown with 37.5 parts by weight of aromatic oil per part by weight. SBR (C) has a styrene content of 2
The oil-extended product with 37.5 parts by weight of aromatic oil per 100 parts by weight of 5% solution-polymerized SBR is shown. The coupled silica is precipitated silica and has a surface area of 175 m ^2.
Capsule 8113 (Cou manufactured by Degussa AG) (Frankfurt, Germany), which was previously subjected to a coupling reaction with 11.3% of / g of bis (3-triethoxysilylpropyl) -tetrasulfide.
A commercially available product as psil 8113) was used. Moreover, 6PPD is N- (1,3-dimethylbutyl) -N'-phenyl-P-phenylenediamine, and CBS is N-cyclohexyl-2-benzthiazole sulfenamide. What is TBBS?
It is Nt-butylbenzothiazole sulfenamide, and DPG means diphenylguanidine.

[0023]

[Table 1]

The rubber compositions of Examples 1 to 3 and Comparative Examples 1 to 3 were vulcanized in a mold at 165 ° C. for 20 minutes to prepare vulcanized rubber test pieces. The vulcanized rubber test piece was subjected to a viscoelasticity test and an abrasion test based on the above method.
The test results are shown in Table 2.

[0025]

[Table 2]

From the results of Example 1 and Comparative Example 1 in Table 2,
When an equal amount of coupled silica (68.0 parts by weight of silica and 7.7 parts by weight of coupling agent) is added in place of carbon black, the loss modulus (E ₂ ) is reduced by 40% at 50 ° C., and the loss compliance ( LC) is also 20%
It can be seen that the rolling resistance of the tire tread made from the composition of Example 1 is reduced.

Further, at 0 ° C., Example 1 favorably balances the increase in loss compliance with the decrease in loss modulus. Therefore, the wet grip can be kept high. It can also be seen that the composition of Example 1 has improved wear resistance. Similarly, with respect to the rubber compositions of Examples 2 and 3, when an equal amount of coupled silica (50.0 parts by weight of silica and 5.5 parts by weight of coupling agent) was added instead of carbon black, 50 It can be seen that the loss modulus (E ₂ ) and the loss compliance (LC) at 0 ° C. are considerably reduced, and the rolling resistance of the tire tread made from the rubber compositions of Examples 2 and 3 is reduced. In addition, in the rubber compositions of Examples 2 and 3, the loss modulus and the loss compliance are preferably balanced at 0 ° C.

For the rubber-based polymer, emulsion polymerization S
It can be seen that in BR (Example 2), E ₂ increased to compensate for the decrease in LC, whereas in solution polymerized SBR (Example 3), LC increased to compensate for the decrease in E ₂ . Further, the wear resistance in the case of using the solution-polymerized SBR (Example 3) was improved. On the other hand, emulsion polymerization SB
When R was used (Example 2), the abrasion resistance was lower than that of Comparative Example 2, but the volume loss was small and acceptable.

Next, an example of a composition prepared by using a two-step mixing technique in which silica and a coupling agent are separately compounded without being previously bound will be described. Examples 4 and 5 and Comparative Example 4 The rubber compositions of Examples 4 and 5 were prepared in which the respective components shown in Table 3 were mixed in a two-stage mixing method, but the discharge temperature in the first stage was different. That is, in the first stage, each composition was mixed in a 2 liter experimental closed mixer for the mixing time shown in Table 1 up to the discharge temperature shown in Table 1, and in the second stage, two roll mills for experiment were used. Mixing was completed by adding the sulfur and accelerator at about 50 ° C. for about 5 minutes. As a comparative example, instead of silica and the coupling agent, an equal amount of carbon black was blended and mixed under the same conditions as in Example 4 to prepare a rubber composition of Comparative Example 4.

[0030]

[Table 3]

In Table 3, SBR used as a rubber polymer
(A) and SBR (B) are the same as those used in Example 1. Silica is a precipitated silica with a surface area of 175 m ² / g and is available from Degussa as Ultrasil VN3 (Ultras).
The commercially available product was used as il VN3).
As the coupling agent, a mixture of bis (3-triethoxysilylpropyl) -tetrasulfide and N330 carbon black in a ratio of 50:50, which was commercially available from Degussa as X-50S, was used.

The prepared rubber compositions of Examples 4 and 5 and Comparative Example 4 were vulcanized in a mold at 165 ° C. for 20 minutes to prepare vulcanized rubber test pieces. This rubber test piece was subjected to the same viscoelasticity test and abrasion test as in Example 1. The results are shown in Table 4.

[0033]

[Table 4]

From Table 4, when silica and a coupling agent were added in place of carbon black (Examples 4 and 5), the loss modulus (E ₂ ) and loss compliance (LC) at 50 ° C. decreased, and It can be seen that the rolling resistance of the tire tread made from Example 4 and Example 5 is reduced. Further, the dynamic modulus (E ^* ) is preferably maintained more favorably when silica is mixed in the first stage at a relatively low temperature of 125 ° C. (Example 5) than when it is mixed at a high temperature (Example 4). I understand. From this, it can be seen that the tire handling characteristics produced by the rubber composition of the present invention can be maintained at the level of a rubber composition containing carbon black (Comparative Example 4). Furthermore, mixing silica at relatively low temperatures was also found to have a satisfactory balance of E ₂ and LC at 0 ° C., which is advantageous for wet grip. Further, it can be seen that the abrasion resistance of the composition of Example 5 is maintained at a level comparable to that of the rubber composition containing carbon black (Comparative Example 4).

Example 6 and Comparative Example 5 A rubber composition of Example 6 having the composition shown in Table 7 was prepared. This is a rubber polymer oil-extended with 44 parts by weight of aromatic oil per 100 parts by weight of solution-polymerized SBR having a styrene content of 40% (SBR (D)).
And a mixture (SBR (E)) oil-extended with 37.5 parts by weight of aromatic oil per 100 parts by weight of solution-polymerized SBR having a styrene content of 31%. The aromatic oil used has a specific gravity of 0.97 and a viscosity (100 ° C.) of 55 cst. The carbon black used had a surface area of 160 mg / g due to iodine adsorption. CBS (N-cyclohexylbenzothiazole sulfenamide) was used as the vulcanization accelerator. As the silica, Ultrasil VN3 (surface area: 175 m ² / g) manufactured by Degussa and used in Examples 4 and 5 was used. The coupling agent was X from Degussa Co., which was used in Examples 4 and 5.
-50S was used.

As a comparative example, a rubber composition containing the same amount of carbon black instead of silica (Comparative Example 5).
Was prepared.

[0037]

[Table 5]

The compositions were mixed in a two step process. That is, the rubber polymer, the filler, and the coupling agent were first mixed, then the oil, and the activator and the protective agent were mixed, and the discharge temperature was about 125 ° C. In the second stage, accelerators and vulcanizing agents were added to the composition and mixed to a final discharge temperature of about 105 ° C. The viscoelastic properties of the vulcanized rubber obtained by curing the mixed composition at 165 ° C. for 20 minutes were measured. The measurement results are shown in Table 6.

[0039]

[Table 6]

As can be seen from Table 6, by incorporating silica in place of carbon black, ta at 0 ° C.
nδ is high, that is, the grip is good and 50
A good balance is obtained with a low tan δ at C (corresponding to low rolling resistance). Next, examples of high-performance tires produced by using the rubber composition of the present invention will be described.

Example 7 The rubber composition of Example 7 was prepared by mixing the components shown in Table 7 in a two-step process. As a rubber-based polymer, 3 per 100 parts by weight of emulsion-polymerized SBR having a styrene content of 40% is used.
What was oil-extended with 7.5 parts by weight of oil (indicated as "emulsion polymerization SBR" in Table 5) was used. As the silica, Ultrasil VN3 (surface area: 175 m ² / g) manufactured by Degussa and used in Examples 4 to 6 was used. The coupling agent is
The X-50S manufactured by Degussa and used in Examples 4 to 6 was used. The aromatic oil used was the same as in Example 6 (specific gravity 0.97, viscosity (100 ° C.) 55c).
st).

The composition was mixed in the same manner as in Example 6. That is, the rubber polymer, the filler, and the coupling agent were first mixed, then the oil, and the activator and the protective agent were mixed, and the discharge temperature was about 125 ° C. In the second stage, accelerators and vulcanizing agents were added to the composition and mixed to a final discharge temperature of about 105 ° C.

[0043]

[Table 7]

A tire using the rubber composition in the tread portion was molded. Vulcanization was performed at about 170 ° C. A standard wet grip tread pattern having a depth of 6 mm was formed on the tire tread. The tire thus produced was tested by a controlled wet test. One set was mounted on a sports car and compared to the test results of a set of standard wet grip tires with similar tread patterns and depths under similar wet conditions.

The average time per meter of the standard test course for the tire of the present invention was 14.78 seconds, which was significantly shorter than the average time of 16.14 seconds for the standard tire. Further, a driver test was performed under wet conditions and compared with a set of standard tires similarly tested. The fastest for the standard tire was 10.6 seconds per meter and the fastest for the tire of the invention was 9.82 seconds per meter, the tire of the invention being shorter.
This means that the driver response was very advantageous with significant improvements being obtained for the tires of the invention in braking, turning and especially traction performance.

The tan δ at 0 ° C. of the vulcanized rubber was measured in the same manner as in Example 1 to find that it was 0.4.
It was 8. 0 ° C of vulcanized rubber obtained by usual compounding
The tan δ in the above was 0.42. T at 0 ° C
The value of an δ is generally used as an index of grip, and the larger the value of tan δ at 0 ° C., the better the grip. The rubber composition of Example 7 has a larger value of tan δ, and the results of the above tire test can be confirmed.

Example 8 The composition of the rubber composition of Example 8 suitable for a high performance tire using coupled silica is shown in Table 8.
As the rubber-based polymer, the emulsion-polymerized SB used in Example 7 was used.
R, that is, emulsion-polymerized SBR1 having a styrene content of 40%
Oil-extended with 37.5 parts by weight of oil per 00 parts by weight was used. Examples of the coupled silica include Examples 1 to 3.
The Capsil 8113 manufactured by Degussa Co. used in the above was used. The same aromatic oil as that used in Examples 6 and 7 was used.

The composition was formulated by the single step method. That is, first, a rubber polymer, carbon black and coupled silica are mixed, then oil and then an activator,
Processing and protection aids were added, and finally vulcanizers and accelerators. The discharge temperature from the blender is about 105 ℃
And

[0049]

[Table 8]

A tire using this rubber composition for a tread was molded. Vulcanization was performed at about 170 ° C. The same tread pattern as in Example 7 was formed. The tire thus created was mounted on a high performance vehicle and tested on a wet test track. As a comparative example, a standard wet grip tire was mounted and the same test was conducted.

The average lap time per meter of the tire of the present invention was 14.67 seconds, which was 1 for the standard tire of the comparative example.
It was significantly shorter than the average lap time per m of 16.14 seconds.

[0052]

The viscoelastic properties of the vulcanized rubber using the rubber composition of the present invention are tan at temperatures of 0 ° C and 50 ° C.
δ and loss compliance are well balanced, good grip and low rolling resistance. Therefore, by using the rubber composition of the present invention, it is possible to provide a high-performance tire capable of reducing rolling resistance while maintaining a good balance between grip and abrasion resistance.

Therefore, the tire prepared by using the rubber composition of the present invention in the tread portion is excellent in abrasion resistance and grip, has low rolling resistance, and can satisfy the requirements of a fuel-efficient vehicle. Further, the motorcycle tire and the automobile tire having the tread composed of the rubber composition of the present invention have improved wet grip as compared with a high performance tire composed of a rubber composition of a general composition.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI technical display location C08L 9/06 (31) Priority claim number 9404983: 0 (32) Priority date March 15, 1994 (33) Priority claiming country United Kingdom (GB) (72) Inventor Gary Terence Barrett Bee, England 44 8B, Birmingham, King Standing, Lekin Road 30

Claims (15)

[Claims] 1. A vulcanizable rubber composition containing a rubber polymer, a vulcanizing agent, a filler, and a coupling agent, wherein the filler contains silica, and the coupling agent contains the silica and A rubber composition, which is at least bifunctional, capable of reacting with the rubber-based polymer. 2. The rubber composition according to claim 1, wherein at least 25% by weight or more of the rubber-based polymer is a styrene-butadiene copolymer. 3. The rubber composition according to claim 2, wherein the styrene content of the styrene-butadiene copolymer is 20 to 50%. 4. The rubber composition according to claim 3, wherein the styrene-butadiene copolymer is an emulsion-polymerized or solution-polymerized styrene-butadiene copolymer. 5. The rubber composition according to claim 1, wherein the silica is contained in an amount of 15 to 160 parts by weight per 100 parts by weight of the rubber polymer. 6. The silica according to claim 1, which has been previously coupled with the coupling agent.
The rubber composition according to any one of 5 above. 7. The rubber composition according to claim 1, wherein the rubber-based polymer, a vulcanizing agent, a filler, and a coupling agent are mixed at 130 ° C. or lower. 8. The rubber composition according to claim 1, wherein the coupling agent is a silane coupling agent or a zirconate salt. 9. The silane coupling agent is bis (3
-Triethoxy-silylpropyl) -tetrasulfide, mercaptopropyltriethoxysilane, vinyltriethoxysilane, or thiocyanatotriethoxysilane. 10. The rubber composition according to claim 8, wherein the zirconate is zirconium dineo alkanato di (3-mercapto) propionate-0. 11. The rubber composition according to claim 1, wherein the coupling agent is contained in an amount of 2 to 20% by weight based on the silica. 12. A carbon black as a filler is further included, and the total content of the filler is 40 to 160 parts by weight per 100 parts by weight of the rubber-based polymer.
11. The rubber composition according to item 11. 13. The rubber composition according to claim 1, which contains at least 40 parts by weight of oil per 100 parts by weight of the rubber polymer. 14. A method for producing a vulcanizable rubber composition, which comprises mechanically mixing a rubber-based polymer, a vulcanizing agent, a filler, and a coupling agent, wherein the filler contains silica, and The method for producing a rubber composition, wherein the coupling agent is at least bifunctional that can react with the silica and the rubber-based polymer, and the mixing step is performed at 130 ° C. or less. 15. A tire comprising a tread made of the rubber composition according to any one of claims 1 to 13.