JP6790707B2 - Vulcanized rubber composition and tires using it - Google Patents

Description

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

Conventionally, the fuel efficiency of a vehicle has been reduced by reducing the rolling resistance of the tire (improving the fuel efficiency performance). Since the rolling resistance of tires is greatly affected by the low heat generation of rubber used for tire members, developments have been actively carried out to realize low heat generation of rubber, and further, it has been adapted to lower fuel consumption. Various formulations have been studied. In particular, as a filler, not only conventional carbon black but also silica, which is advantageous for fuel efficiency, is often used.

On the other hand, as a method of improving various tire performances such as fuel efficiency, low temperature characteristics, ice / snow performance, and wear resistance in a well-balanced manner, a method of blending a plurality of polymer (rubber) components (polymer blend) has been used for a long time. It was. Specifically, as a rubber component in a tire, it has become mainstream to blend some polymer components typified by styrene-butadiene rubber (SBR), butadiene rubber (BR), and natural rubber (NR). .. This is a means to bring out the physical properties of the vulcanized rubber composition, which cannot be achieved by a single polymer component, by utilizing the characteristics of each polymer component.

In this polymer blend, the phase structure (morphology) of each rubber component after vulcanization and the distribution of a filler such as silica to each rubber phase (uneven distribution of silica) are important factors that determine physical properties. It becomes. The factors that determine morphology and control of uneven distribution of fillers are extremely complicated, and many studies have been conducted to express tire physical properties in a well-balanced manner, but there is room for improvement in each case.

Patent Document 1 discloses a rubber composition for sidewalls, which is a compounded polymer blend containing natural rubber and butadiene rubber and exhibiting a sea-island structure, in which silica is unevenly distributed in its discontinuous phase. , There is no description about the polymer blend of styrene-butadiene rubber and butadiene rubber.

Japanese Unexamined Patent Publication No. 2006-348222

On the other hand, in the case of a polymer blend of butadiene rubber (BR) and styrene-butadiene rubber (SBR), silica is unevenly distributed in the SBR, the BR is not sufficiently reinforced, stress is not evenly applied to the entire rubber, and wear resistance is achieved. There is a problem that the destruction resistance performance cannot be improved, and the dispersibility of the entire system deteriorates, so that the fuel efficiency performance cannot be improved.

Therefore, an object of the present invention is to provide a vulcanized rubber composition capable of improving wear resistance, fuel efficiency and fracture resistance in a well-balanced manner, and a tire having a tire member using the vulcanized rubber composition.

The present invention
[1] It has a phase containing styrene-butadiene rubber and silica incompatible with butadiene rubber (SBR phase) and a phase containing butadiene rubber and silica (BR phase).
The SBR phase and the BR phase are incompatible with each other,
A vulcanized rubber composition in which the abundance α of silica in the SBR phase after vulcanization satisfies the following formula 1 and the ratio β of styrene-butadiene rubber incompatible with butadiene rubber satisfies the following formula 2.
0.3 ≤ α ≤ 0.7 (preferably 0.5 ≤ α ≤ 0.6) (Equation 1)
0.4 ≤ β ≤ 0.8 (preferably 0.5 ≤ β ≤ 0.7) (Equation 2)
(Here, α = amount of silica in the SBR phase / (amount of silica in the SBR phase + amount of silica in the BR phase), and β = (styrene-butadiene rubber incompatible with the butadiene rubber in the vulcanized rubber composition). (Mass of all rubber components in the vulcanized rubber composition)).
[2] The abundance γ of silica with respect to the ratio β of styrene-butadiene rubber incompatible with butadiene rubber satisfies the following formula 3.
The vulcanized rubber composition according to the above [1], wherein the dispersion ratio δ of silica in the entire system satisfies the following formula 4.
0.6 ≤ γ ≤ 1.4 (preferably 0.8 ≤ γ ≤ 1.2) (Equation 3)
δ ≤ 0.8 (preferably δ ≤ 0.6) (Equation 4)
(Here, γ = α / β, and δ = standard deviation of the distance between silicas / average distance between silicas.)
[3] The above [1] or the above [1], which contains 15 to 120 parts by mass, preferably 50 to 100 parts by mass of silica, with respect to 100 parts by mass of a rubber component containing styrene-butadiene rubber and butadiene rubber that are incompatible with butadiene rubber. [2] The vulcanized rubber composition,
[4] The filler is contained in an amount of 15 to 120 parts by mass, preferably 30 to 100 parts by mass with respect to 100 parts by mass of a rubber component containing styrene-butadiene rubber and butadiene rubber which are incompatible with the butadiene rubber. The vulcanized rubber composition according to the above [1] or [2], which contains 50% by mass or more, preferably 70% by mass or more of silica with respect to the total amount of filler.
[5] The vulcanized rubber composition according to any one of the above [1] to [4], wherein the butadiene rubber is a butadiene rubber having a cis 1,4 bond content of 90% or more, preferably 95% or more.
[6] The above [1] contains 15 to 80 parts by mass, preferably 20 to 70 parts by mass of a softener with respect to 100 parts by mass of a rubber component containing styrene-butadiene rubber and butadiene rubber that are incompatible with butadiene rubber. The present invention relates to a tire having a tread composed of the vulcanized rubber composition according to any one of [5] and [7] the vulcanized rubber composition according to any one of [1] to [6] above.

According to the present invention, in an incompatible system having a phase containing styrene-butadiene rubber and silica incompatible with butadiene rubber (SBR phase) and a phase containing butadiene rubber and silica (BR phase), the SBR phase is contained. Since it is a vulcanized rubber composition in which the abundance α of silica and the ratio β of styrene-butadiene rubber incompatible with butadiene rubber are within a predetermined range, fuel efficiency, wear resistance, and fracture resistance are improved in a well-balanced manner. Can provide vulcanized tires.

It is a figure which shows the SEM photograph of the vulcanized rubber composition (a) which disperses silica well, and the vulcanized rubber composition (b) which silica is unevenly distributed.

The vulcanized rubber composition of the present invention has a phase containing styrene-butadiene rubber and silica incompatible with butadiene rubber (SBR phase) and a phase containing butadiene rubber and silica (BR phase), and the SBR phase and The BR phase is incompatible with each other, the abundance α of silica in the SBR phase after vulcanization satisfies the following formula 1, and the ratio β of styrene-butadiene rubber incompatible with butadiene rubber is the following formula 2. Fulfill.
0.3 ≤ α ≤ 0.7 (Equation 1)
0.4 ≤ β ≤ 0.8 (Equation 2)
(Here, α = amount of silica in the SBR phase / (amount of silica in the BR phase + amount of silica in the SBR phase), and β = (styrene-butadiene rubber incompatible with the butadiene rubber in the vulture rubber composition). (Mass of all rubber components in the vulgarized rubber composition), and the mass of styrene-butadiene rubber incompatible with butadiene rubber in the vulgarized rubber composition is contained in the production of the vulnerable rubber. It corresponds to the mass of styrene-butadiene rubber that is incompatible with butadiene rubber, and the mass of all rubber components in the sulfide rubber composition corresponds to the mass of all rubber components contained in the production of sulfide rubber. To do.)

The dispersed state of silica in the rubber component in the vulcanized rubber composition can be observed by a scanning electron microscope (SEM). For example, in an example in which the dispersion of silica, which is one embodiment of the present invention, is good, as seen in FIG. 1 (a), the phase (SBR phase) 1 containing styrene-butadiene rubber incompatible with butadiene rubber is present. The sea phase is formed, the phase (BR phase) 2 containing butadiene rubber forms an island phase, and the silica 3 is dispersed in both the SBR phase 1 and the BR phase 2. On the other hand, unlike the aspect of the present invention, in the example in which silica is unevenly distributed in one phase, as seen in FIG. 1 (b), the SBR phase 1 is the sea phase as in FIG. 1 (a). The BR phase 2 forms an island phase, but the silica 3 is unevenly distributed in the SBR phase 1 and is not dispersed in both phases.

The vulcanized rubber composition of the present invention has a phase containing styrene-butadiene rubber and silica incompatible with butadiene rubber (SBR phase) and a phase containing butadiene rubber and silica (BR phase), and the SBR phase and The BR phase is incompatible with each other. Here, in the present specification, "incompatible" means, for example, when used in a vulcanized rubber composition, when the structure of the sea island can be clearly observed in the cross section of the vulcanized rubber composition, or when it is clearly observed. Even if it is not possible, it means that the identifiable phase structure changes when the compounding ratio is changed, and the contrast changes in correlation with the change in the ratio. For example, it is easier to obtain an image taken by a scanning electron microscope (SEM). Can be evaluated. Alternatively, the vulcanized rubber composition is measured by, for example, a DSC (Differential Scanning Calorimetry), and when two Tg peaks are obtained, it means that those components are incompatible.

In addition, whether SBR is compatible with BR or incompatible with BR, for example, as the amount of styrene in SBR increases and the amount of vinyl decreases, SBR tends to become incompatible with BR. It can be roughly predicted from the quantity, but it is difficult to make a general decision. Therefore, whether the SBR is compatible with BR or incompatible with BR is determined by kneading the target SBR and BR together with an additive such as a vulcanizer at, for example, 130 to 160 ° C. for 3 to 10 minutes. For example, vulcanize at 140 to 170 ° C. for 10 to 60 minutes, and confirm the vulcanized rubber composition by analyzing an image taken by, for example, a scanning electron microscope (SEM) according to the method as described above. Is preferable.

Further, in the vulcanized rubber composition of the present invention, wear resistance, fuel efficiency and fracture resistance are improved when the abundance α of silica in the SBR phase satisfies the following formula 1. In the present specification, "the abundance α of silica in the SBR phase" is an index showing how much of the total amount of silica in the vulcanized rubber composition is present in the SBR phase after vulcanization.
0.3 ≤ α ≤ 0.7 (Equation 1)
(Here, α = the amount of silica in the SBR phase / (the amount of silica in the SBR phase + the amount of silica in the BR phase).)

Specifically, for example, the vulcanized rubber composition is surfaced and used as a sample. Ten regions of 2 μm × 2 μm that do not overlap with each other are selected for a scanning electron microscope (SEM) photograph of one sample. In each region, the silica area per unit area and the silica area in the SBR phase in the unit area are measured, and the silica abundance rate of the SBR phase is calculated. If it can be confirmed that the difference between the maximum value and the minimum value of the silica abundance at 10 places is within 10%, the average of the silica abundance at the 10 places is defined as α.

The abundance α of silica in the SBR phase is 0.3 or more, preferably 0.5 or more. When the abundance α of silica in the SBR phase is less than 0.3, improvement in wear resistance, fuel efficiency, and fracture resistance cannot be expected and tends to deteriorate. The abundance α of silica in the SBR phase is 0.7 or less, preferably 0.6 or less. When the abundance α of silica in the SBR phase exceeds 0.7, improvement in wear resistance, fuel efficiency, and fracture resistance cannot be expected, but rather tends to decrease.

In the vulcanized rubber composition of the present invention, the ratio β of the styrene-butadiene rubber incompatible with the butadiene rubber satisfies the following formula 2.
0.4 ≤ β ≤ 0.8 (Equation 2)
(Here, β = (mass of styrene-butadiene rubber incompatible with butadiene rubber in vulture rubber composition / mass of all rubber components in vulture rubber composition), and in the vulture rubber composition. The mass of the styrene-butadiene rubber incompatible with the butadiene rubber corresponds to the mass of the styrene-butadiene rubber incompatible with the butadiene rubber contained in the production of the vulture rubber, and the total amount in the vulture rubber composition. The mass of the rubber component corresponds to the mass of all the rubber components contained in the production of the vulture rubber.)

The ratio β of the styrene-butadiene rubber incompatible with the butadiene rubber is 0.4 or more, preferably 0.5 or more. When the ratio β of the styrene-butadiene rubber incompatible with the butadiene rubber is less than 0.4, improvement in fuel efficiency performance tends not to be expected. The proportion β of the styrene-butadiene rubber incompatible with the butadiene rubber is 0.8 or less, preferably 0.7 or less. When the ratio β of the styrene-butadiene rubber incompatible with the butadiene rubber exceeds 0.8, the content of the butadiene rubber is reduced, and there is a tendency that improvement in fracture resistance and wear resistance cannot be expected. Further, the ratio β of the styrene-butadiene rubber incompatible with the butadiene rubber in the vulcanized rubber composition is such that the vulcanized rubber composition actually obtained is obtained by a pyrolysis gas chromatograph / mass spectrometer (PyGC / MS) or the like. It can also be obtained by measuring using a measuring device.

Further, in the vulcanized rubber composition of the present invention, it is preferable that the abundance γ of silica with respect to the ratio β of the styrene-butadiene rubber incompatible with the butadiene rubber satisfies the following formula 3.
0.6 ≤ γ ≤ 1.4 (Equation 3)
(Here, γ = α / β.)

In the present specification, "silica abundance γ" is the silica abundance in the SBR phase with respect to the ratio β of styrene-butadiene rubber incompatible with butadiene rubber. Ideally, when silica is distributed in the SBR phase, the abundance γ of silica is 1.

The silica abundance γ with respect to the ratio β of the styrene-butadiene rubber incompatible with the butadiene rubber is preferably 0.6 or more, more preferably 0.8 or more. By setting the silica abundance γ to the ratio β of the styrene-butadiene rubber incompatible with the butadiene rubber to 0.6 or more, the wear resistance performance and the fuel consumption performance tend to be improved. The silica abundance γ with respect to the ratio β of the styrene-butadiene rubber incompatible with the butadiene rubber is preferably 1.4 or less, more preferably 1.2 or less. By setting the silica abundance γ with respect to the ratio β of styrene-butadiene rubber incompatible with butadiene rubber to 1.4 or less, wear resistance, fuel efficiency, and fracture resistance tend to be improved.

In the vulcanized rubber composition of the present invention, it is preferable that the dispersion ratio δ of silica in the entire system satisfies the following formula 4.
δ ≤ 0.8 (Equation 4)
(Here, δ = standard deviation of distance between silicas / average distance between silicas.)

In the present specification, the "average distance between silicas" is the distance between adjacent wall surfaces of silica aggregates. The silica aggregate is expanded to fill the image to create a pseudo Voronoi polygon, and the distance between the aggregates of the aggregates to which the pseudo Voronoi polygon is adjacent is measured. The distance between the agglomerates can be obtained by finding the distance between the points where the agglomerates are closest to each other. For example, using an image taken with a scanning electron microscope (SEM), it can be easily calculated by a commercially available program such as LUZEX® AP of Nireco Corporation.

The dispersion ratio δ of silica in the entire system is preferably 0.8 or less, more preferably 0.7 or less. By setting the dispersion ratio δ of silica in the entire system to 0.8 or less, silica is dispersed in the entire system, and physical properties such as wear resistance, fuel efficiency, and fracture resistance tend to be improved. The dispersion ratio δ of silica is most preferably 0.

The styrene-butadiene rubber incompatible with butadiene rubber is not particularly limited as long as it is incompatible with butadiene rubber, and emulsified polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), and the like. Modified SBR modified from these SBRs (modified E-SBR, modified S-SBR) and the like, which are common in the tire industry, can be used. These may be used alone or in combination of two or more.

The BR used in the present invention is not particularly limited, and for example, a BR having a cis 1,4 bond content of less than 50% (Rare earth BR) and a BR having a cis 1,4 bond content of 90% or more ( HISIS BR), rare earth butadiene rubber synthesized using a rare earth element catalyst (rare earth BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (HISIS modified BR, rosis modified BR) Etc. can be used. Among them, it is preferable to use at least one selected from the group consisting of high-cis unmodified BR, high-cis modified BR, low-cis unmodified BR and low-cis-modified BR, and it is more preferable to use high-cis unmodified BR.

Examples of the HISIS BR include BR730 and BR51 manufactured by JSR Corporation, BR1220 manufactured by Zeon Corporation, and BR130B, BR150B and BR710 manufactured by Ube Industries, Ltd. Among the high cis BRs, those having a cis 1,4-bond content of 95% or more are more preferable. These may be used alone or in combination of two or more. By containing HISIS BR, low temperature characteristics and wear resistance can be improved. Examples of the locis BR include BR1250 manufactured by Nippon Zeon Corporation. These may be used alone or in combination of two or more.

The modified BR is not particularly limited, but a modified BR having an alkoxyl group as a modifying group in the BR is preferable, and a high-cis modified BR is more preferable.

The silica is not particularly limited, and for example, silica prepared by a dry method (silicic anhydride), silica prepared by a wet method (hydrous silicic acid), and the like commonly used in the tire industry are used. can do.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 70 m ² / g or more, and more preferably 140 m ² / g or more. By setting the N ₂ SA of silica to 70 m ² / g or more, sufficient reinforcing properties can be obtained, and fracture resistance and wear resistance can be improved. The N ₂ SA of silica is preferably 220 m ² / g or less, more preferably 200 m ² / g or less. By setting the N ₂ SA of silica to 220 m ² / g or less, the silica can be easily dispersed and the workability can be improved. Here, N ₂ SA of silica in the present specification is a value measured by the BET method according to ASTM D3037-81.

The content of silica is preferably 15 parts by mass or more, and more preferably 50 parts by mass or more with respect to 100 parts by mass of the rubber component. By setting the total content of silica to 15 parts by mass or more, wear resistance, fracture resistance, and fuel efficiency tend to be improved. The total content of silica is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, with respect to 100 parts by mass of the rubber component. By setting the total content of silica to 120 parts by mass or less, workability and workability are improved, and there is a tendency to prevent deterioration of low temperature characteristics due to an increase in the amount of silica.

In addition to the above materials, the vulcanized rubber composition of the present invention contains, if necessary, SBR incompatible with BR and other rubber components other than BR, a silane coupling agent, a filler such as carbon black, an oil, and the like. It is preferable to contain a softening agent, a wax, an antiaging agent, stearic acid, zinc oxide, a vulcanizing agent, a vulcanization accelerator, and various other materials generally used in the tire industry.

Other rubber components include SBR compatible with BR, natural rubber (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile butadiene. (NBR) and the like. Whether these rubber components are contained in the BR phase or the SBR phase in the vulcanized rubber composition, or are not contained in either the BR phase or the SBR phase to form a third phase is determined by each rubber component. It is determined by the compatibility with BR and SBR, and can be confirmed by analyzing the vulcanized rubber composition for testing as described above.

The total content of the styrene-butadiene rubber incompatible with the butadiene rubber, the butadiene rubber, and the styrene-butadiene rubber compatible with the butadiene rubber in the total rubber components of the vulgarized rubber composition of the present invention is preferably 80% by mass or more. , 90% by mass or more is more preferable, and 100% by mass is further preferable. The larger the total content of styrene-butadiene rubber that is incompatible with butadiene rubber, butadiene rubber, and styrene-butadiene rubber that is compatible with butadiene rubber, the more wear resistance, fracture resistance, and fuel efficiency can be exhibited. preferable. In addition, since there is a high correlation between the specified ranges of α, β, and γ and the performance of the function, the rubber components are styrene-butadiene rubber, which is incompatible with butadiene rubber, butadiene rubber, and rubber consisting only of styrene-butadiene rubber, which is compatible with butadiene rubber. It is preferable to use the ingredients. When a rubber component contained in the SBR phase or a rubber component not included in the SBR phase is used as the other rubber component, in order to obtain a sufficient correlation between the specified range of α, β and γ and the function. The total of these other rubber components is preferably 10% by mass or less, and more preferably 5% by mass or less, based on the total rubber components of the vulcanized rubber composition.

The silane coupling agent is not particularly limited, but in the rubber industry, any silane coupling agent conventionally used in combination with silica can be used in combination, for example, bis (3-triethoxysilylpropyl). ) Tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) tri Sulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl Tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-trimethoxysilylethyl-N, N-dimethylthio Sulfides such as carbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide Systems; mercapto systems such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; vinyl such as vinyltriethoxysilane and vinyltrimethoxysilane Systems; Amino systems such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane; Glysidoxy series such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane; 3-nitropropyltri Nitro system such as methoxysilane, 3-nitropropyltriethoxysilane; 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxycy Orchids, chloro systems such as 2-chloroethyltrimethoxysilane and 2-chloroethyltriethoxysilane; and the like. These silane coupling agents may be used alone or in combination of two or more. Of these, a sulfide system is preferable, and bis (3-triethoxysilylpropyl) disulfide is particularly preferable, from the viewpoint of good reactivity with silica.

When the silane coupling agent is contained, the content with respect to 100 parts by mass of silica is preferably 3 parts by mass or more, and more preferably 6 parts by mass or more. By setting the content of the silane coupling agent to 3 parts by mass or more, the fracture resistance can be improved. The content of the silane coupling agent with respect to 100 parts by mass of silica is preferably 12 parts by mass or less, and more preferably 10 parts by mass or less. By setting the content of the silane coupling agent to 12 parts by mass or less, an effect commensurate with the increase in cost can be obtained.

Examples of carbon black include furnace black, acetylene black, thermal black, channel black, graphite, and the like, and these carbon blacks may be used alone or in combination of two or more. Of these, furnace black is preferable because it can improve low temperature characteristics and wear resistance in a well-balanced manner.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 70 m ² / g or more, and more preferably 90 m ² / g or more, from the viewpoint of obtaining sufficient reinforcing properties and wear resistance. Also, N ₂ SA of carbon black is excellent in dispersibility, from the viewpoint that it is difficult to heat generation, preferably 300 meters ² / g or less, more preferably 250m ² / g. N ₂ SA can be measured according to JIS K 6217-2 "Carbon black for rubber-Basic characteristics-Part 2: How to obtain specific surface area-Nitrogen adsorption method-Single point method".

When carbon black is contained, the content of the total rubber component with respect to 100 parts by mass is preferably 1 part by mass or more, and more preferably 5 parts by mass or more. By setting the content of carbon black to 1 part by mass or more, sufficient reinforcing properties tend to be obtained. The carbon black content is preferably 105 parts by mass or less, more preferably 60 parts by mass or less, and further preferably 20 parts by mass or less. By setting the content of carbon black to 105 parts by mass or less, workability is improved, heat generation is suppressed, and wear resistance can be improved.

The oil is not particularly limited, but for example, process oil, vegetable oil or fat or a mixture thereof can be used. As the process oil, for example, a paraffin-based process oil, an aroma-based process oil, a naphthenic process oil, or the like can be used. Vegetable oils and fats include castor oil, cottonseed oil, flaxseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pineapple, tall oil, corn oil, rice oil, benibana oil, sesame oil, olive oil, Examples include sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Of these, it is preferable to use a process oil, particularly a paraffin-based process oil.

When oil is contained, the content of the total rubber component with respect to 100 parts by mass is preferably 15 parts by mass or more, more preferably 20 parts by mass or more. By setting the oil content to 15 parts by mass or more, the workability tends to be improved. The oil content is preferably 80 parts by mass or less, more preferably 70 parts by mass or less. By setting the oil content to 80 parts by mass or less, there is a tendency to prevent deterioration of workability, deterioration of wear resistance, and deterioration of aging resistance.

As the anti-aging agent used in the present invention, amine-based, phenol-based, and imidazole-based compounds and anti-aging agents such as carbamic acid metal salts can be appropriately selected and blended, and these anti-aging agents can be blended. , May be used alone, or two or more kinds may be used in combination. Of these, amine-based antiaging agents are preferable because they can significantly improve ozone resistance and have long-lasting effects, and N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine is more preferable. ..

When the anti-aging agent is contained, the content of the total rubber component with respect to 100 parts by mass is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and further preferably 1.2 parts by mass or more. By setting the content of the antiaging agent to 0.5 parts by mass or more, sufficient ozone resistance tends to be obtained. The content of the antiaging agent is preferably 8 parts by mass or less, more preferably 4 parts by mass or less, and further preferably 2.5 parts by mass or less. By setting the content of the antiaging agent to 8 parts by mass or less, discoloration can be suppressed and bleeding tends to be suppressed.

As the wax, stearic acid, and zinc oxide, those generally used in the rubber industry can be preferably used.

The vulcanizing agent is not particularly limited, and those common in the rubber industry can be used, but those containing a sulfur atom are preferable, and powdered sulfur is particularly preferably used.

The vulcanization accelerator is also not particularly limited, and those common in the rubber industry can be used.

The vulcanized rubber composition of the present invention preferably contains 15 to 120 parts by mass of a filler with respect to 100 parts by mass of a rubber component containing styrene-butadiene rubber and butadiene rubber that are incompatible with butadiene rubber.

The content of the filler is preferably 15 parts by mass or more, and more preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. By setting the filler content to 15 parts by mass or more, wear resistance, fracture resistance, and fuel efficiency tend to be improved. The filler content is preferably 120 parts by mass or less, more preferably 100 parts by mass or less. By setting the filler content to 120 parts by mass or less, workability and workability are improved, and there is a tendency to prevent deterioration of low temperature characteristics due to an increase in the amount of filler. The filler includes silica, carbon black, aluminum hydroxide and the like, and it is preferable to blend silica in an amount of preferably 50% by mass or more, more preferably 70% by mass or more based on the total amount of the filler.

The vulcanized rubber composition of the present invention preferably contains 15 to 80 parts by mass of a softener with respect to 100 parts by mass of a rubber component containing styrene-butadiene rubber and butadiene rubber that are incompatible with butadiene rubber.

The content of the softener is preferably 15 parts by mass or more, and more preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. By setting the content of the softener to 15 parts by mass or more, the workability tends to be improved. The content of the softening agent is preferably 80 parts by mass or less, more preferably 70 parts by mass or less. By setting the content of the softener to 80 parts by mass or less, there is a tendency to prevent deterioration of workability, deterioration of wear resistance, and deterioration of aging resistance. The softener includes aroma oil, naphthenic oil, paraffin oil, terpene resin and the like.

As a method for producing the vulcanized rubber composition of the present invention, a known method can be used. For example, each component is kneaded with a Banbury mixer, a kneader, an open roll, or the like, and then vulcanized. it can.

Further, the kneading step when producing the vulgarized rubber composition of the present invention is a method of kneading all the rubber components and silica at once according to the type of rubber to be used, butadiene rubber. A method of adding styrene-butadiene rubber incompatible with butadiene rubber to a kneaded product kneaded with silica and kneading the mixture, or adding styrene butadiene rubber and silica incompatible with butadiene rubber to a kneaded product obtained by kneading butadiene rubber with silica. A method of kneading with the addition of and a method of kneading after preparing a master batch of each rubber component and silica can be appropriately selected.

The vulcanized rubber composition of the present invention can be used for each member of a tire, for example, tire applications such as treads, carcass, sidewalls, beads, as well as anti-vibration rubbers, belts, hoses, and other industrial products. .. Among them, it is preferably used for a tread because it has excellent fuel efficiency, abrasion resistance and fracture resistance, and when the tread is a two-layer tread consisting of a cap tread and a base tread. It is preferably used for cap treads.

The tire of the present invention can be produced by a usual method using the vulcanized rubber composition of the present invention. That is, in the unvulcanized stage of the vulcanized rubber composition of the present invention, the rubber composition is extruded according to the shape of the tread of the tire, bonded together with other tire members on the tire molding machine, and by a usual method. The tire of the present invention can be manufactured by forming an unvulcanized tire by molding and heating and pressurizing the unvulcanized tire in a vulcanizer.

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

Example 1 , Example 2, Reference Example 3, Example 4, Reference Example 5, Example 6 and Comparative Examples 1 to 3.
Wear resistance, fuel efficiency, and fracture resistance were evaluated by the following tests for each vulcanized rubber composition having the values shown in Table 1 for the indexes α, β, γ, and δ of the vulcanized rubber composition. It was. The results of each test are shown in Table 1. The α, δ, wear resistance, fuel efficiency, and fracture resistance are measured and evaluated after the vulcanized rubber composition is stored at room temperature and 200 hours after the completion of vulcanization (about 1 week later). I went about. β corresponds to the content (mass) of styrene-butadiene rubber incompatible with butadiene rubber with respect to the total rubber component (mass) contained in the production of the vulcanized rubber composition, and γ is α / β. ..

<Abrasion resistance>
Using a Ramborn wear tester manufactured by Iwamoto Seisakusho Co., Ltd., the amount of wear was measured at a surface rotation speed of 50 m / min, a load of 3.0 kg, a sandfall amount of 15 g / min, and a slip rate of 20%. Was taken the reciprocal of. Then, the reciprocal of the wear amount of Comparative Example 1 was set to 100, and the reciprocal of the other wear amounts was expressed as an index. The larger the index, the better the wear resistance. The performance target value is 105 or more.

<Fuel efficiency performance>
A strip-shaped test piece having a width of 1 mm or 2 mm and a length of 40 mm was punched out from the sheet-shaped vulcanized rubber composition and used for the test. Using a spectrometer manufactured by Ueshima Seisakusho Co., Ltd., tan δ was measured at a dynamic strain amplitude of 1%, a frequency of 10 Hz, and a temperature of 50 ° C., and tan δ of each formulation was expressed as an index by the following formula. The larger the index, the lower the rolling resistance and the better the fuel efficiency. The performance target value is 105 or more.
(Fuel efficiency performance index) = (tan δ of Comparative Example 1) / (tan δ of each formulation) × 100

<Destruction resistance>
The tear strength (N / mm) of the angle-shaped test piece without cuts made of the vulcanized rubber composition is determined according to the test method of JIS K 6252 "Vulcanized rubber and thermoplastic rubber-How to determine the tear strength". It was measured. Then, the tear strength of each compound was expressed as a fracture resistance index by the following formula. The larger the index, the higher the tear strength and the better the fracture resistance. The performance target value is 105 or more.
(Fracture resistance index) = (Tear strength of each formulation) / (Tear strength of Comparative Example 1) x 100

<Evaluation of morphology and uneven distribution of silica>
The vulcanized rubber composition was surfaced and observed using a scanning electron microscope (SEM). The morphology of each phase could be confirmed by comparing the contrasts. As a result, in the vulcanized rubber compositions of Example 1 , Example 2, Reference Example 3, Example 4, Reference Example 5, Example 6 and Comparative Examples 1 to 3, styrene-butadiene incompatible with butadiene rubber. It was confirmed that the phase containing rubber (SBR phase) and the phase containing butadiene rubber (BR phase) are incompatible with each other.

Silica is observable in granular form. Ten 2 μm × 2 μm regions that did not overlap each other were selected for the SEM photograph of one sample. In each region, the silica area per unit area of each phase was measured, and the silica abundance of the SBR phase was calculated. It was confirmed that the difference between the maximum value and the minimum value of the values at 10 locations was within 10%, and the average of 10 locations was defined as α.

<Evaluation of silica dispersion rate>
The SEM observation image is converted into a binarized image of the rubber part and the silica part, and the average distance between the closest silica aggregates is calculated using the automatic image processing analysis system LUZEX® AP manufactured by Nireco Co., Ltd. , The standard deviation was calculated and δ was calculated.

From the results in Table 1, in an incompatible system having a phase containing styrene-butadiene rubber and silica incompatible with butadiene rubber (SBR phase) and a phase containing butadiene rubber and silica (BR phase), silica in the SBR phase By using a vulcanized rubber composition in which the abundance α of styrene-butadiene rubber and the ratio β of styrene-butadiene rubber incompatible with butadiene rubber are within a predetermined range, wear resistance, fuel efficiency and fracture resistance are improved in a well-balanced manner. I know I can do it.

Hereinafter, various materials used in Production Reference Examples 1 to 6 and Production Comparative Reference Examples 1 to 3 are collectively shown. The vulcanized rubber compositions obtained in Production Reference Examples 1 to 6 and Production Comparative Reference Examples 1 to 3 are described in Example 1 , Example 2, Reference Example 3, Example 4, Reference Example 5, and Example 6 above. And the vulcanized rubber compositions of Comparative Examples 1 to 3 respectively.
Styrene-butadiene rubber (SBR1): Prepared in Synthesis Example 1 below (incompatible with BR)
Styrene-butadiene rubber (SBR2): Prepared in Synthesis Example 2 below (compatible with BR)
Butadiene rubber (BR1): BR730 manufactured by JSR Corporation (unmodified, cis 1,4-content 95%)
Butadiene rubber (BR2): BR150B manufactured by Ube Industries, Ltd. (unmodified, cis 1,4-content rate 98%)
Butadiene rubber (BR3): Prepared in Synthesis Example 3 below Carbon black: Diablack I (ISAF, N ₂ SA: 114 m ² / g, average particle size: 23 nm) manufactured by Mitsubishi Chemical Corporation.
Silica: ULTRASIL® VN3 (N ₂ SA: 175m ² / g) manufactured by Evonik Industries AG (EVONIK INDUSTRIES AG)
Silane coupling agent: Si266 made by Evonik Industries AG
Mineral oil: PS-32 (paraffin-based process oil) manufactured by Idemitsu Kosan Co., Ltd.
Stearic acid: "paulownia" manufactured by NOF CORPORATION
Zinc oxide: Zinc oxide type 2 anti-aging agent manufactured by Mitsui Metal Mining Co., Ltd .: Nocrack 6C (N- (1,3-dimethylbutyl) -N-phenyl-p-phenylene) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd. Diamine)
Wax: Ozoace wax manufactured by Nippon Seikan Co., Ltd. Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd. NS: Noxeller NS (N-tert-butyl-) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. 2-benzothiazolyl vulcan amide)
Vulcanization accelerator DPG: Noxeller D (1,3-diphenylguanidine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

Synthesis Example 1: Synthesis of SBR To a nitrogen-substituted 100 ml ampoule bottle, 28 g of cyclohexane and 8.6 mmol of tetramethylethylenediamine were added, and 6.1 mmol of n-butyllithium was added. Then, 8.0 g of isoprene was slowly added and reacted in an ampoule bottle at 60 ° C. for 120 minutes to obtain an isoprene block (referred to as initiator 1).

The weight average molecular weight of the initiator 1 was 2200, the vinyl bond content was 72.3 (mass%), and the molecular weight distribution (Mw / Mn) was 1.08.

Next, 4000 g of cyclohexane, 483.5 g of 1,3-butadiene, 211.5 g of styrene, and 0.18 g of tetramethylethylenediamine were charged into an autoclave with a stirrer under a nitrogen atmosphere, and then the total amount of the initiator 1 was added to 40 ° C. Polymerization was started at. After confirming that the polymerization conversion was in the range of 95% to 100%, 0.08 mmol of 1,6-bis (trichlorosilyl) hexane was added in a cyclohexane solution having a concentration of 20% by mass for 10 minutes. It was reacted. Further, 0.027 mmol of polyorganosiloxane A represented by the following formula (I) was added in the form of a xylene solution having a concentration of 20% by mass, and the mixture was reacted for 30 minutes. Then, as a polymerization terminator, methanol corresponding to twice the molar amount of n-butyllithium used was added to obtain a solution containing modified SBR. To this solution, Irganox 1520L (manufactured by Ciba Speciality Chemicals) as an antiaging agent was added in an amount of 0.15 part by mass based on 100 parts by mass of the modified SBR, and then the solvent was removed by steam stripping. Vacuum dried at ° C. for 24 hours to give a solid modified SBR.

(In the formula, X ₁ is
Is. )

The resulting modified SBR, was measured for various physical properties by the measuring method described below, is 90.0 weight-average molecular weight (× 10 ^4), the molecular weight distribution (Mw / Mn) of 1.65, The styrene unit content (mass%) of the styrene-butadiene copolymer contained in the portion other than the isoprene block is 41, and the vinyl bond in the butadiene monomer unit in the styrene-butadiene copolymer contained in the portion other than the isoprene block. The content (%) was 30, the Mooney viscosity (ML _{1 + 4} (100 ° C.)) was 84.0, and it was incompatible with BR.

[Weight average molecular weight, molecular weight distribution (Mw / Mn)]
Measured under the following conditions using a gel permeation chromatograph (trade name; HLC-8020, manufactured by Tosoh Corporation) and a differential refractometer RI-8020 (manufactured by Tosoh Corporation) as a detector. , Calculated as standard polystyrene conversion value.
Column: Two GMH-HR-H (manufactured by Tosoh Corporation) are connected in series. Column temperature: 40 ° C,
Mobile phase: tetrahydrofuran,

[Styrene unit content and vinyl bond content]
The styrene unit content and vinyl bond content were measured by ^{1 1} H-NMR analysis.

[Moony Viscosity (ML _{1 + 4} (100 ° C))]
The measurement was performed according to JIS K 630-1: 2001.

[Compatibility with BR]
The compatibility of the obtained SBR1 with respect to BR was evaluated by measuring a vulcanized rubber composition having a mass ratio of 70:30 with BR1 by SEM.

Synthesis Example 2: Synthesis of SBR2 The inside of a stainless steel polymerization reactor having an internal volume of 20 liters was washed, dried, replaced with dry nitrogen, hexane (specific gravity 0.68 g / cm ³ ) 10.2 kg, 1,3-butadiene 547 g. , 173 g of styrene, 6.1 ml of tetrahydrofuran, and 5.0 ml of ethylene glycol diethyl ether were charged into the polymerization reactor. Next, 13.1 mmol of n-butyllithium was added as an n-hexane solution to initiate polymerization.

The stirring speed was 130 rpm, the temperature inside the polymerization reactor was 65 ° C., and the copolymerization of 1,3-butadiene and styrene was carried out for 3 hours while continuously supplying the monomers into the polymerization reactor. The supply amount of 1,3-butadiene in the total polymerization was 821 g, and the supply amount of styrene was 259 g.

Next, the obtained polymer solution was stirred at a stirring speed of 130 rpm, 11.1 mmol of 3-diethylaminopropyltriethoxysilane was added, and the mixture was stirred for 15 minutes. 20 ml of a hexane solution containing 0.54 ml of methanol was added to the polymer solution, and the polymer solution was further stirred for 5 minutes.

2-tert-Butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumilyzer (registered trademark)) in the polymer solution Add 1.8 g of GM) and 0.9 g of pentaerythrityltetrakis (3-laurylthiopropionate) (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumilyzer (registered trademark) TP-D), and then steam strike. The polymer was recovered from the polymer solution by ripping.

The obtained SBR2, was measured for various physical properties by the same measuring method as in Synthesis Example 1, a weight average molecular weight (× 10 ⁴⁾ 95.0, molecular weight distribution (Mw / Mn) be 1.1 , The styrene unit content (% by mass) was 25, the vinyl bond content (%) was 59, the Mooney viscosity (ML _{1 + 4} (100 ° C.)) was 75, and it was compatible with BR. ..

Synthesis Example 3: Production of BR3 (1) Synthesis of conjugated diene-based polymer In advance, a cyclohexane solution containing 0.18 mmol of neodymium versaticate, a toluene solution containing 3.6 mmol of methylarmoxane, and 6.7 mmol of hydrogen. A catalyst composition (iodine atom) obtained by reaction-aging a toluene solution containing diisobutylaluminum silicate, a toluene solution containing 0.36 mmol of trimethylsilyliodide, and 0.90 mmol of 1,3-butadiene at 30 ° C. for 60 minutes. / Lantanoid-containing compound (molar ratio) = 2.0) was obtained. Subsequently, 2.4 kg of cyclohexane and 300 g of 1,3-butadiene were placed in a nitrogen-substituted 5 L autoclave. Then, the catalyst composition was put into the autoclave and polymerized at 30 ° C. for 2 hours to obtain a polymer solution. The reaction conversion rate of the added 1,3-butadiene rubber was almost 100%.

Here, in order to measure various physical property values of the conjugated diene-based polymer (hereinafter, also referred to as “polymer”), that is, the polymer before modification, 200 g of the polymer solution is extracted from the above-mentioned polymer solution, and this polymer is obtained. A methanol solution containing 1.5 g of 2,4-di-tert-butyl-p-cresol was added to the solution to stop the polymerization reaction, desolvated by steam stripping, and dried on a roll at 110 ° C. The obtained dried product was used as a polymer.

When various physical property values of the polymer were measured by the measurement methods shown below, the Mooney viscosity (ML _{1 + 4} (100 ° C.)) was 12, the molecular weight distribution (Mw / Mn) was 1.6, and the cis. The -1,4-bonding amount was 99.2% by mass, and the 1,2-vinyl bonding amount was 0.21% by mass.

[Moony Viscosity (ML _{1 + 4} (100 ° C))]
According to JIS K 6300, the measurement was performed using an L rotor under the conditions of preheating 1 minute, rotor operating time 4 minutes, and temperature 100 ° C.

[Molecular weight distribution (Mw / Mn)]
A gel permeation chromatograph (trade name; HLC-8120GPC, manufactured by Tosoh Corporation) was used, and a differential refractometer was used as a detector to measure under the following conditions and calculated as a standard polystyrene conversion value.
Column; Product name "GMHHXL", 2 (manufactured by Tosoh),
Column temperature; 40 ° C,
Mobile phase; tetrahydrofuran,
Flow velocity; 1.0 ml / min,
Sample concentration; 10 mg / 20 ml

[Sith-1,4-bonding amount, 1,2-vinyl binding amount]
The content of cis-1,4-bond and 1,2-vinyl bond were measured by ^{1 1} H-NMR analysis and ¹³ C-NMR analysis. The trade name "EX-270" manufactured by JEOL Ltd. was used for the NMR analysis. Specifically, as ¹ H-NMR analysis, the polymer was obtained from the signal intensities at 5.30 to 5.50 ppm (1,4-bond) and 4.80 to 5.01 ppm (1,2-bond). The ratio of 1,4-bond and 1,2-bond in the above was calculated. Furthermore, as for ¹³ C-NMR analysis, the signal intensities at 27.5 ppm (cis-1,4-bond) and 32.8 ppm (trans-1,4-bond) show that cis-1,4 in the polymer. The ratio of −-bond to trans-1,4-bond was calculated. From these calculated ratios, the cis-1,4-bonded amount (mass%) and the 1,2-vinyl bond amount (mass%) were used.

(2) Modification of Conjugated Diene Polymer In order to obtain BR3, the polymer solution of the conjugated diene polymer obtained in (1) was subjected to the following treatment. A toluene solution containing 1.71 mmol of 3-glycidoxypropyltrimethoxysilane was added to the polymer solution maintained at a temperature of 30 ° C., and the mixture was reacted for 30 minutes to obtain a reaction solution. Then, a toluene solution containing 1.71 mmol of 3-aminopropyltriethoxysilane was added to this reaction solution, and the mixture was stirred for 30 minutes. Subsequently, a toluene solution containing 1.28 mmol of tetraisopropyl titanate was added to this reaction solution, and the mixture was stirred for 30 minutes. Then, in order to stop the polymerization reaction, a methanol solution containing 1.5 g of 2,4-di-tert-butyl-p-cresol was added to prepare this solution as a modified polymer solution. The yield was 2.5 kg. Subsequently, 20 L of an aqueous solution adjusted to pH 10 with sodium hydroxide was added to this modified polymer solution, and a condensation reaction was carried out at 110 ° C. for 2 hours with desolvation. Then, it dried with a roll of 110 degreeC, and the modified polymer BR3 was obtained.

When various physical property values of the obtained BR3 were measured by the following measuring methods (however, the molecular weight distribution (Mw / Mn) was measured under the same conditions as the above polymer), Mooney viscosity (ML). _{1 + 4} (125 ° C.)) is 46, the molecular weight distribution (Mw / Mn) is 2.4, the cold flow value is 0.3 mg / min, the stability over time is 2, and the glass transition temperature. Was −106 ° C.

[Moony Viscosity (ML _{1 + 4} (125 ° C))]
According to JIS K 6300, the measurement was performed using an L rotor under the conditions of preheating 1 minute, rotor operating time 4 minutes, and temperature 125 ° C.

[Cold flow value]
The measurement was carried out by extruding the polymer through a 1/4 inch orifice at a pressure of 3.5 lb / in ² and a temperature of 50 ° C. After leaving for 10 minutes to bring it into a steady state, the extrusion speed was measured and the measured value was displayed in milligrams per minute (mg / min).

[Stability over time]
The Mooney viscosity (ML _{1 + 4} (125 ° C.)) after storage in a constant temperature bath at 90 ° C. for 2 days was measured, and is a value calculated by the following formula. The smaller the value, the better the stability over time.
Formula: [Moony viscosity after storage in a constant temperature bath at 90 ° C for 2 days (ML _{1 + 4} (125 ° C))]-[Moony viscosity measured immediately after synthesis (ML _{1 + 4} (125 ° C))]

[Glass-transition temperature]
The glass transition temperature is measured according to JIS K 7121 by using a differential scanning calorimeter (Q200) manufactured by TA Instruments Japan Co., Ltd. while raising the temperature at a heating rate of 10 ° C./min. , Was determined as the glass transition start temperature.

Manufacturing Reference Examples 1 to 6 and Comparative Manufacturing Reference Examples 1 to 3
According to the formulation shown in step (I) of Table 2, rubber components, silica and other materials are added and kneaded at a discharge temperature of 150 ° C. for 3 minutes using a 1.7 L Banbury mixer to obtain a kneaded product. It was. Next, the obtained kneaded product and other materials were added according to the formulation shown in step (II) of Table 2, and kneaded at a discharge temperature of 150 ° C. for 2 minutes to obtain a kneaded product. Sulfur and a vulcanization accelerator were added to the obtained kneaded product according to the formulation of step (III) in Table 2, and kneaded at 150 ° C. for 5 minutes using an open roll to obtain an unvulcanized rubber composition. It was. For Production Reference Examples 1, 4 and 5, kneaded products having the compounding formulations shown in each column of Table 2 were obtained in step (I), and both kneaded products were used in step (II).

Each of the obtained unvulcanized rubber compositions was press-vulcanized at 170 ° C. for 12 minutes with a mold having a thickness of 0.5 mm to obtain a vulcanized rubber composition.

1 SBR phase 2 BR phase 3 silica

Claims (6)

It has a phase containing styrene-butadiene rubber and silica that are incompatible with butadiene rubber (SBR phase) and a phase containing butadiene rubber and silica (BR phase).
The butadiene rubber is one having a weight average molecular weight does not include the 1.0 × 10 ³ ~2.0 × 10 ⁵ epoxidized polybutadiene,
The SBR phase and the BR phase are incompatible with each other , and the incompatible phase means that when Tg is measured by a differential scanning calorimeter for a vulcanized rubber composition having the SBR phase and the BR phase. Two peaks are obtained,
The abundance α of silica in the SBR phase after vulcanization satisfies the following formula 1 .
The proportion β of incompatible styrene-butadiene rubber meets the following formula 2 to butadiene rubber,
The abundance γ of silica with respect to the ratio β of styrene-butadiene rubber incompatible with butadiene rubber satisfies the following formula 3 and
Dispersion ratio δ vulcanized rubber composition satisfying the following formula 4 of the entire system of the silica.
0.3 ≤ α ≤ 0.7 (Equation 1)
0.4 ≤ β ≤ 0.8 (Equation 2)
(Here, α = amount of silica in the SBR phase / (amount of silica in the SBR phase + amount of silica in the BR phase), and β = (styrene-butadiene rubber incompatible with the butadiene rubber in the vulcanized rubber composition). (Mass of all rubber components in the vulcanized rubber composition)).
0.6 ≤ γ ≤ 1.4 (Equation 3)
δ ≤ 0.7 (Equation 4)
(Here, γ = α / β, and δ = standard deviation of the distance between silicas / average distance between silicas.) Per 100 parts by mass of the rubber component containing a styrene-butadiene rubber incompatible butadiene rubber and a butadiene rubber, silica containing 15 to 120 parts by claim 1 vulcanized rubber composition. The filler is contained in an amount of 15 to 120 parts by mass with respect to 100 parts by mass of a rubber component containing styrene-butadiene rubber and butadiene rubber which are incompatible with the butadiene rubber, and the filler is 50% by mass or more based on the total amount of the filler. vulcanized rubber composition according to claim 1, further comprising silica. The vulcanized rubber composition according to any one of claims 1 to 3 , wherein the butadiene rubber is a butadiene rubber having a cis 1,4 bond content of 90% or more. The vulcanization according to any one of claims 1 to 4 , wherein 15 to 80 parts by mass of a softener is contained in 100 parts by mass of a rubber component containing styrene-butadiene rubber and butadiene rubber which are incompatible with butadiene rubber. Rubber composition. A tire having a tread composed of the vulcanized rubber composition according to any one of claims 1 to 5 .