JP7020152B2 - Rubber composition for tires and pneumatic tires - Google Patents

Description

The present invention relates to a rubber composition for a tire and a pneumatic tire.

Conventionally, tires have been required to have various performances such as low fuel consumption, wet grip performance, wear resistance, and rubber strength, and wet grip performance has been regarded as important from the viewpoint of safety.

As a technique for improving the wet grip performance, there are a method of blending a large amount of filler and resin, a method of blending a special filler such as aluminum hydroxide in addition to a general filler such as carbon black and silica, and the like. Although it has been proposed, further improvement is desired (see, for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 2014-09300 Japanese Unexamined Patent Publication No. 2005-213353

An object of the present invention is to solve the above-mentioned problems and to provide a rubber composition for a tire and a pneumatic tire having excellent wet grip performance.

The present invention is a rubber composition for a tire containing a rubber component, silica and a silane coupling agent, wherein the blending amount A of the silica with respect to 100 parts by mass of the rubber component A and the silane coupling agent with respect to 100 parts by mass of the rubber component. B, the nitrogen adsorption ratio surface area N ₂ SA of the silica, the body integral ratio φ of the silica in the rubber composition for tires, and 100% of the vulgarized rubber of the rubber composition for tires at 23 ° C. The present invention relates to a rubber composition for a tire, wherein the elongation stress M100 satisfies the relationship of the following formula (I).
A / B / N ₂ SA / φ / M100 ≦ 0.015 (I)

A in the above formula (I) represents the blending amount (parts by mass) of silica with respect to 100 parts by mass of the rubber component. B represents the blending amount (parts by mass) of the silane coupling agent with respect to 100 parts by mass of the rubber component. N ₂ SA represents the nitrogen adsorption specific surface area (m ² / g) of silica. φ represents the volume fraction of silica in the rubber composition for tires. M100 represents the 100% elongation stress (MPa) of the vulcanized rubber of the rubber composition for tires at 23 ° C.

The rubber composition for tires preferably has a styrene-butadiene rubber content of 50% by mass or more in 100% by mass of the rubber component.

In the rubber composition for tires, the blending amount A of silica with respect to 100 parts by mass of the rubber component is preferably 80 parts by mass or more.

In the rubber composition for tires, the blending amount B of the silane coupling agent with respect to 100 parts by mass of the rubber component is preferably 12 parts by mass or more.

The nitrogen adsorption specific surface area of the silica is preferably 300 m ² / g or more.

The rubber composition for tires is preferably a rubber composition for tread.

The present invention also relates to a pneumatic tire having a tire member using the above-mentioned rubber composition for a tire, and the tire member satisfies the above formula (I).

According to the present invention, a rubber composition for a tire containing a rubber component, silica and a silane coupling agent, wherein the blending amount A of the silica with respect to 100 parts by mass of the rubber component A and the silane cup with respect to 100 parts by mass of the rubber component. The blending amount B of the ring agent, the nitrogen adsorption specific surface area N ₂ SA of the silica, the body integral ratio φ of the silica in the rubber composition for tires, and the sulfide rubber of the rubber composition for tires at 23 ° C. Since the rubber composition for a tire is characterized in that the 100% elongation stress M100 satisfies the relationship of the above formula (I), excellent wet grip performance can be imparted.

The rubber composition for a tire contains a rubber component, silica and a silane coupling agent, and has a silica compounding amount A, a silane coupling agent compounding amount B, a nitrogen adsorption specific surface area N ₂ SA of silica, and a body integral of silica. The ratio φ and the 100% elongation stress M100 of the vulcanized rubber (vulcanized rubber composition for tires) at 23 ° C. satisfy the relationship of the above formula (I). This provides excellent wet grip performance.

The reason why such an action effect is obtained is not always clear, but it is presumed as follows.
There are generally three elements of friction: (1) adhesive friction, (2) hysteresis friction, and (3) anchor friction, but especially in wet grips with a water film between the road surface and rubber, (2). It is presumed that the contribution of the hysteresis friction of is increased. Hysteresis friction is represented by the energy loss lost when the rubber is deformed due to the unevenness of the road surface, and in order to reproduce the same phenomenon as the input, it is generally considered that it can be shown by tan δ near 0 ° C. Has been done.

As a method for increasing the tan δ of rubber, it is useful to add a large amount of filler to increase the heat generation point of the rubber, and it is presumed that it is particularly useful to add silica when increasing the tan δ near 0 ° C. Ru. In that case, it is presumed that the strength (quality and quantity) of the interaction between the polymer and silica is important, but the lower the value of the blending ratio between the silica to be blended and the silane coupling agent, the better the blending ratio with respect to the silane coupling agent. It shows that the amount of silica compounded is small and the quality of the interaction between the polymer and silica is high.

Further, the product of the body integral ratio φ of silica, the nitrogen adsorption ratio surface area N ₂ SA of silica, and the 100% elongation stress M100 of vulcanized rubber (vulcanized rubber composition for tires) at 23 ° C. is It shows the characteristics of each silica species and has a good correlation with the amount of bound rubber, so it shows the strength of the interaction between the polymer and silica.

Therefore, in the present invention, the blending amount A of silica, the blending amount B of the silane coupling agent, the nitrogen adsorption specific surface area N ₂ SA of silica, the volume fraction φ of silica, and the vulcanized rubber (for vulcanized tires) By using the above formula (I) expressed by combining the 100% elongation stress M100 at 23 ° C. of the rubber composition) and setting the upper limit of 0.015 as the reference value, an index of wet grip in the formulation is used. It was completed by finding the finding that it can be done. Therefore, it is presumed that the rubber composition satisfying the above formula (I) has excellent wet grip performance.

The rubber composition satisfies the following formula (I).
A / B / N ₂ SA / φ / M100 ≦ 0.015 (I)

A in the above formula (I) represents the blending amount (parts by mass) of silica with respect to 100 parts by mass of the rubber component. B represents the blending amount (parts by mass) of the silane coupling agent with respect to 100 parts by mass of the rubber component. N ₂ SA represents the nitrogen adsorption specific surface area (m ² / g) of silica. φ represents the volume fraction of silica in the rubber composition for tires. M100 represents the 100% elongation stress (MPa) of the vulcanized rubber of the rubber composition for tires at 23 ° C.

By setting it below the upper limit, good wet grip performance can be obtained. The value of (A / B / N ₂ SA / φ / M100) is preferably 0.013 or less, more preferably 0.011 or less, further preferably 0.008 or less, and particularly preferably 0.004 or less. The lower limit is not particularly limited, but for example, a large denominator M100 means that the rubber is hard, and if the rubber is too hard, the actual contact area with the road surface may not be sufficient, so 0.0001. The above is preferable, and 0.0005 or more is more preferable.

M100 in the above formula (I) represents 100% elongation stress (MPa) at 23 ° C. of the vulcanized rubber (vulcanized rubber composition for tires) of the rubber composition for tires, which is 3.5 MPa. The above is preferable, 4.0 MPa or more is more preferable, 4.4 MPa or more is further preferable, 6.0 MPa or more is further preferable, 7.5 MPa or more is particularly preferable. The M100 is preferably 20 MPa or less, more preferably 18 MPa or less, further preferably 15 MPa or less, and particularly preferably 12 MPa or less. Within the above range, good wet grip performance tends to be obtained.

In the present specification, the 100% elongation stress M100 (MPa) of the formula (I) is based on JIS K6251 and is subjected to a tensile test at 23 ° C. and 500 mm / min to measure the stress at 100% elongation. The value.

In the rubber composition after vulcanization, the relationship of the above formula (I), the above M100 (MPa), the rubber component, silica, and the silane coupling agent described later are appropriately selected, and the blending amount thereof is appropriately adjusted. , Etc. can be given. Specifically, a method of using a large amount of SBR as a rubber component, a method of increasing the blending amount of silica, a method of increasing the nitrogen adsorption specific surface area of silica, a method of increasing the blending amount of a silane coupling agent, and a method of increasing silica. It can be given by a method of dividing and kneading.

The relationship of the above formula (I) and other means for imparting the above M100 (MPa) include a method of adjusting the blending amount of sulfur and a vulcanization accelerator.

The rubber composition for a tire contains a rubber component, and for example, a diene-based rubber can be used.
Examples of the diene rubber include isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber ( NBR) and the like. Examples of rubber components other than the above include butyl rubber and fluororubber. These may be used alone or in combination of two or more. As the rubber component, SBR, BR, and isoprene-based rubber are preferable, and SBR is more preferable.

Here, the rubber component preferably has a weight average molecular weight (Mw) of 200,000 or more, and more preferably 350,000 or more. The upper limit of Mw is not particularly limited, but is preferably 4 million or less, more preferably 3 million or less.

In the present specification, Mw and number average molecular weight (Mn) are gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: manufactured by Tosoh Corporation. It can be obtained by standard polystyrene conversion based on the measured value by TSKGEL SUPERMULTIPORE HZ-M).

The rubber component may be a non-modified diene-based rubber or a modified diene-based rubber.
The modified diene-based rubber may be any diene-based rubber having a functional group that interacts with a filler such as silica. For example, at least one end of the diene-based rubber is a compound (modifying agent) having the above functional group. End-modified diene-based rubber modified with (terminal-modified diene-based rubber having the above-mentioned functional group at the end), main-chain-modified diene-based rubber having the above-mentioned functional group in the main chain, and the above-mentioned functional group at the main chain and the end. Main chain terminal modified diene rubber (for example, main chain terminal modified diene rubber having the above functional group in the main chain and having at least one end modified with the above modifying agent), or two or more in the molecule. Examples thereof include end-modified diene-based rubbers that have been modified (coupled) with a polyfunctional compound having an epoxy group and introduced with a hydroxyl group or an epoxy group.

Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group and a disulfide. Examples thereof include a group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group and an epoxy group. .. In addition, these functional groups may have a substituent. Among them, an amino group (preferably an amino group in which the hydrogen atom of the amino group is replaced with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxy group having 1 to 6 carbon atoms). An alkoxysilyl group having 1 to 6 carbon atoms) is preferable.

The SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR) and the like can be used. These may be used alone or in combination of two or more.

The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less. When it is within the above range, the above effect can be obtained more preferably.
In the present specification, the styrene content of SBR is calculated by H1 ^- NMR measurement.

As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Co., Ltd., Zeon Corporation, etc. can be used.

The SBR may be a non-modified SBR or a modified SBR. Examples of the modified SBR include a modified SBR into which a functional group similar to that of the modified diene rubber is introduced.

When SBR is contained, the content of SBR in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and may be 100% by mass. Within the above range, good wet grip performance tends to be obtained.

The BR is not particularly limited, and for example, a high cis BR having a high cis content, a BR containing syndiotactic polybutadiene crystals, a BR synthesized using a rare earth catalyst, and the like can be used. These may be used alone or in combination of two or more. Among them, a high cis BR having a cis content of 90% by mass or more is preferable because the wear resistance is improved.

Further, the BR may be a non-modified BR or a modified BR. Examples of the modified BR include modified BR into which a functional group similar to that of the modified diene rubber is introduced.

As the BR, for example, products such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used.

Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR and the like. As the NR, for example, SIR20, RSS # 3, TSR20 and the like, which are common in the tire industry, can be used. The IR is not particularly limited, and for example, an IR 2200 or the like, which is common in the tire industry, can be used. Modified NR includes deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc., and modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of the modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, and the like. These may be used alone or in combination of two or more.

The rubber composition contains silica. By using silica, good wet grip performance can be obtained.

The blending amount A of silica with respect to 100 parts by mass of the rubber component is preferably 80 parts by mass or more, more preferably 85 parts by mass or more, further preferably 90 parts by mass or more, still more preferably 100 parts by mass or more, and particularly preferably 115 parts by mass. More than parts, most preferably 130 parts by mass or more. The blending amount A is preferably 400 parts by mass or less, more preferably 300 parts by mass or less, still more preferably 250 parts by mass or less, and particularly preferably 200 parts by mass or less. Within the above range, good wet grip performance tends to be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 300 m ² / g or more, more preferably 330 m ² / g or more, still more preferably 350 m ² / g or more, still more preferably 370 m ² / g or more, and particularly. It is preferably 400 m ² / g or more. The N ₂ SA is preferably 550 m ² / g or less, more preferably 500 m ² / g or less, and further preferably 450 m ² / g or less. Within the above range, good wet grip performance tends to be obtained.
The nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

The volume fraction φ of silica in the rubber composition for tires is a value that can be obtained from the blending amount of silica in the rubber composition for tires and the specific gravity of silica, and is a real number exceeding 0 and less than 1. .. The volume fraction φ of silica is, for example, preferably 0.10 or more, more preferably 0.15 or more, further preferably 0.20 or more, further preferably 0.23 or more, and particularly preferably 0.30 or more. The volume fraction φ is preferably 0.65 or less, more preferably 0.55 or less, further preferably 0.45 or less, and particularly preferably 0.40 or less.

Examples of silica include dry silica (anhydrous silica) and wet silica (hydrous silica), but wet silica is preferable because of the large number of silanol groups.

As the silica, for example, products such as Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation can be used.

In the rubber composition, the content of silica in 100% by mass of the filler is preferably 80% by mass or more, more preferably 85% by mass or more, and further preferably 90% by mass or more from the viewpoint of wet grip performance. .. The upper limit is not particularly limited.

The rubber composition contains a silane coupling agent together with silica. This provides good wet grip performance.

The content of the silane coupling agent is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 3 parts by mass or more with respect to 100 parts by mass of silica. The content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 25 parts by mass or less. Within the above range, good wet grip performance tends to be obtained.

The blending amount B of the silane coupling agent with respect to 100 parts by mass of the rubber component is preferably 12 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 18 parts by mass or more, still more preferably 22 parts by mass or more. Particularly preferably, it is 27 parts by mass or more. The blending amount B is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 35 parts by mass or less. Within the above range, good wet grip performance tends to be obtained.

The silane coupling agent is not particularly limited, and for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, and the like. Bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis ( 3-Triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilylethyl) ) Disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, 3- Sulfide type such as triethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, Mercapto type such as NXT and NXT-Z manufactured by Momentive, vinyl triethoxysilane, vinyl tri Vinyl-based such as methoxysilane, amino-based such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane, glycidoxy such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane. Examples thereof include nitro-based systems such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, and chloro-based systems such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These may be used alone or in combination of two or more. Among them, the mercapto type is preferable because good wet grip performance can be obtained.

As the silane coupling agent having a mercapto group, a silane coupling agent containing a binding unit A represented by the following formula (II-1) and a binding unit B represented by the following formula (II-2) can be preferably used. ..

In the above equations (II-1) and (II-2), x is an integer of 0 or more, and y is an integer of 1 or more. R ¹ is hydrogen, halogen, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched alkynyl group having 2 to 30 carbon atoms, or a branched or unbranched alkynyl group. The hydrogen at the end of the alkyl group is substituted with a hydroxyl group or a carboxyl group. R ² represents a branched or non-branched alkylene group having 1 to 30 carbon atoms, a branched or non-branched alkenylene group having 2 to 30 carbon atoms, or a branched or non-branched alkynylene group having 2 to 30 carbon atoms. A ring structure may be formed by R ¹ and R ² .

In the silane coupling agent having the above structure, the content of the binding unit A is preferably 30 mol% or more, more preferably 50 mol% or more, preferably 99 mol% or less, and more preferably 90 mol% or less. .. The content of the binding unit B is preferably 1 mol% or more, more preferably 5 mol% or more, still more preferably 10 mol% or more, preferably 70 mol% or less, and more preferably 65 mol% or less. More preferably, it is 55 mol% or less. The total content of the binding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%.
The content of the binding units A and B is an amount including the case where the binding units A and B are located at the end of the silane coupling agent. The form when the binding units A and B are located at the terminal of the silane coupling agent is not particularly limited, and forms a unit corresponding to the formulas (II-1) and (II-2) representing the binding units A and B. You just have to.

Examples of the halogen of R ¹ include chlorine, bromine, and fluorine.

The branched or non-branched alkyl group of R1 having ¹ to 30 carbon atoms includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, and a tert-. Examples thereof include a butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group and a decyl group. The alkyl group preferably has 1 to 12 carbon atoms.

Examples of the branched or non-branched alkenyl group of ^R1 having 2 to 30 carbon atoms include a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 1-pentenyl group and a 2-pentenyl. Examples thereof include a group, a 1-hexenyl group, a 2-hexenyl group, a 1-octenyl group and the like. The alkenyl group preferably has 2 to 12 carbon atoms.

Examples of the branched or non-branched alkynyl group having 2 to 30 carbon atoms of R ¹ include an ethynyl group, a propynyl group, a butynyl group, a pentynyl group, a hexynyl group, a heptinyl group, an octynyl group, a nonynyl group, a decynyl group and an undecynyl group. Dodecynyl group and the like can be mentioned. The alkynyl group preferably has 2 to 12 carbon atoms.

Examples of the branched or non-branched alkylene group having 1 to 30 carbon atoms of ^R2 include an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group and an undecylene group. Examples thereof include a dodecylene group, a tridecylene group, a tetradecylene group, a pentadecylene group, a hexadecylene group, a heptadecylene group and an octadecylene group. The alkylene group preferably has 1 to 12 carbon atoms.

Examples of the branched or non-branched alkenylene group having ² to 30 carbon atoms include a vinylene group, a 1-propenylene group, a 2-propenylene group, a 1-butenylene group, a 2-butenylene group, a 1-pentenylene group and a 2-pentenylene group. Examples thereof include a group, a 1-hexenylene group, a 2-hexenylene group, and a 1-octenylene group. The number of carbon atoms of the alkenylene group is preferably 2 to 12.

Examples of the branched or non-branched alkynylene group having ² to 30 carbon atoms include an ethynylene group, a propynylene group, a butynylene group, a pentynylene group, a hexynylene group, a heptinylene group, an octynylene group, a nonignylene group, a decynylene group and an undecynylene group. Dodecinylene group and the like can be mentioned. The alkynylene group preferably has 2 to 12 carbon atoms.

In a silane coupling agent containing the binding unit A represented by the formula (II-1) and the binding unit B represented by the formula (II-2), the number of repetitions (x) of the binding unit A and the number of repetitions of the binding unit B. The total number of repetitions (x + y) of (y) is preferably in the range of 3 to 300. Within this range, good reactivity with silica and rubber components can be ensured.

Examples of the silane coupling agent containing the binding unit A represented by the formula (II-1) and the binding unit B represented by the formula (II-2) include NXT-Z30, NXT-Z45, and NXT manufactured by Momentive. -Z60 or the like can be used. These may be used alone or in combination of two or more.

As the silane coupling agent, for example, products such as Degussa, Momentive, Shinetsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Toray Dow Corning Co., Ltd. can be used.

The rubber composition may further contain a filler other than silica (reinforcing filler).
Other fillers include, but are not limited to, carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, mica and the like. Of these, carbon black is preferable because it provides good wet grip performance.

Examples of carbon black include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550 and N762. These may be used alone or in combination of two or more.

When carbon black is contained, the content of carbon black is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. The content of carbon black is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, further preferably 25 parts by mass or less, and particularly preferably 20 parts by mass or less. By keeping it within the above range, there is a tendency that excellent wet grip performance can be imparted while ensuring good fuel efficiency.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 120 m ² / g or more, and more preferably 130 m ² / g or more. By setting it above the lower limit, good wet grip performance tends to be obtained. The N ₂ SA is preferably 200 m ² / g or less, more preferably 170 m ² / g or less, and even more preferably 155 m ² / g or less. By setting it below the upper limit, good dispersion of carbon black tends to be obtained.
The nitrogen adsorption specific surface area of carbon black is determined by JIS K6217-2: 2001.

As carbon black, for example, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nikka Carbon Co., Ltd., Columbia Carbon Co., Ltd., etc. Can be used.

The rubber composition may contain a plasticizer. The plasticizer is not particularly limited, and examples thereof include oil, a liquid polymer (liquid diene polymer), and a liquid resin. One type of these plasticizers may be used, or two or more types may be used in combination.

When the plasticizer is contained, the content thereof is preferably 10 parts by mass or more, more preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 30 parts by mass or less, more preferably 25 parts by mass or less. When the content of the plasticizer is in such a range, excellent wet grip performance tends to be obtained while ensuring good fuel efficiency.

Among the plasticizers, at least one selected from the group consisting of oil, liquid polymer, and liquid resin is preferable, and oil is particularly preferable from the viewpoint of processability and wet grip performance.

From the environmental point of view, the polycyclic aromatic content (PCA) is preferably less than 3% by mass, more preferably less than 1% by mass. The polycyclic aromatic content (PCA) is measured according to the British Petroleum Society 346/92 method.

The above oils are not particularly limited, and are paraffin-based process oils, aroma-based process oils, naphthen-based process oils and other process oils, low PCA (polycyclic aromatic) process oils such as TDAE and MES, vegetable oils and fats, and oils and fats. Conventionally known oils such as these mixtures can be used. Of these, aroma-based process oils are preferable in terms of wear resistance and fracture properties. Specific examples of the aroma-based process oil include Diana process oil AH series manufactured by Idemitsu Kosan Co., Ltd.

The liquid polymer (liquid diene polymer) is a diene polymer in a liquid state at room temperature (25 ° C.).
The liquid diene polymer preferably has a polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of 1.0 × ^{10 3} to 2.0 × 105. It is more preferably 0 × 10 ³ to 1.5 × 10 ⁴ .
In the present specification, Mw of the liquid diene polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

Examples of the liquid diene polymer include a liquid styrene-butadiene polymer (liquid SBR), a liquid butadiene polymer (liquid BR), a liquid isoprene polymer (liquid IR), and a liquid styrene isoprene copolymer (liquid SIR). Be done.

The liquid resin is not particularly limited, and examples thereof include a liquid aromatic vinyl polymer, a kumaron indene resin, an indene resin, a terpene resin, a rosin resin, and hydrogenated compounds thereof.

The liquid aromatic vinyl polymer is a resin obtained by polymerizing α-methylstyrene and / or styrene, and is a homopolymer of styrene, a homopolymer of α-methylstyrene, α-methylstyrene and styrene. Examples thereof include liquid resins such as copolymers.

The liquid kumaron inden resin is a resin containing kumaron and inden as the main monomer component constituting the skeleton (main chain) of the resin, and as a monomer component that may be contained in the skeleton other than kumaron and inden. , Styrene, α-methylstyrene, methylindene, vinyltoluene and other liquid resins.

The liquid indene resin is a liquid resin containing indene as a main monomer component constituting the skeleton (main chain) of the resin.

The liquid terpene resin is a liquid typified by a resin obtained by polymerizing a terpene compound such as α-pinene, β-pinene, kanfel, and zipene, and a terpene phenol which is a resin obtained by using a terpene compound and a phenolic compound as raw materials. It is a terpene-based resin.

The liquid rosin resin is a liquid rosin-based resin typified by natural rosin, polymerized rosin, modified rosin, ester compounds thereof, or hydrogenated additives thereof.

A solid resin (a polymer in a solid state at room temperature (25 ° C.)) may be blended with the rubber composition.

When the solid resin is contained, the content thereof is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 20 parts by mass or less. Within the above range, good wet grip performance tends to be obtained.

The solid resin is not particularly limited, but for example, a solid styrene resin, a Kumaron inden resin, a terpene resin, a pt-butylphenol acetylene resin, an acrylic resin, and a dicyclopentadiene resin (DCPD resin). , C5 series petroleum resin, C9 series petroleum resin, C5C9 series petroleum resin and the like. These may be used alone or in combination of two or more.

The solid styrene resin is a solid polymer using a styrene monomer as a constituent monomer, and examples thereof include a polymer obtained by polymerizing a styrene monomer as a main component (50% by mass or more). Specifically, styrene-based monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-Chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) are individually polymerized, and in addition to copolymers obtained by copolymerizing two or more styrene-based monomers, styrene-based monomers And other monomer copolymers that can be copolymerized with this.

Examples of the other monomers include acrylonitriles such as acrylonitrile and methacrylate, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, chloroprene and butadiene. Examples thereof include dienes such as isoprene, olefins such as 1-butane and 1-pentene; α, β-unsaturated carboxylic acids such as maleic anhydride or acid anhydrides thereof;

Of these, solid α-methylstyrene resin (α-methylstyrene homopolymer, copolymer of α-methylstyrene and styrene, etc.) is preferable.

Examples of the solid Kumaron inden resin include solid resins having the same structural units as the above-mentioned liquid Kumaron inden resin.

Examples of the solid terpene resin include polyterpenes, terpenephenols, aromatic-modified terpene resins and the like.
Polyterpene is a resin obtained by polymerizing a terpene compound and a hydrogenated additive thereof. The _terpene compound is a hydrocarbon having a composition of _{( C 5 H 8} ) _n and an oxygen _- containing derivative _thereof . ), Etc., which are compounds having a terpene as a basic skeleton, for example, α-pinene, β-pinene, dipentene, limonene, milsen, aloocimen, ossimen, α-ferandrene, α-terpinene, γ-terpinene, terpinolene. , 1,8-Cineol, 1,4-Cineol, α-terpineol, β-terpineol, γ-terpineol and the like.

Examples of the solid polyterpene include terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin made from the above-mentioned terpene compound, and hydrogenation to the terpene resin. Also mentioned are solid resins such as treated hydrogenated terpene resins.

Examples of the solid terpene phenol include a solid resin obtained by copolymerizing the terpene compound and a phenol-based compound, and a solid resin obtained by hydrogenating the resin. Specific examples thereof include the terpene compound, the phenol-based compound, and the solid resin. Examples thereof include a solid resin obtained by condensing formalin. Examples of the phenolic compound include phenol, bisphenol A, cresol, xylenol and the like.

Examples of the solid aromatic-modified terpene resin include a solid resin obtained by modifying a terpene resin with an aromatic compound, and a solid resin obtained by hydrogenating the resin. The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring, and for example, a phenol compound such as a phenol, an alkylphenol, an alkoxyphenol, or an unsaturated hydrocarbon group-containing phenol; naphthol, alkylnaphthol, alkoxynaphthol, etc. Naftor compounds such as unsaturated hydrocarbon group-containing naphthols; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, unsaturated hydrocarbon group-containing styrene; kumaron, inden and the like can be mentioned.

Examples of the solid pt-butylphenol acetylene resin include a solid resin obtained by subjecting pt-butylphenol to acetylene in a condensation reaction.

The solid acrylic resin is not particularly limited, but a solvent-free acrylic solid resin can be preferably used from the viewpoint that a resin having few impurities and a sharp molecular weight distribution can be obtained.

The solid solvent-free acrylic resin is a high-temperature continuous polymerization method (high-temperature continuous lump polymerization method) (US Pat. No. 4,414) without using polymerization initiators, chain transfer agents, organic solvents, etc. as auxiliary raw materials as much as possible. , 370, Japanese Patent Application Laid-Open No. 59-6207, Japanese Patent Application Laid-Open No. 5-58805, Japanese Patent Application Laid-Open No. 1-313522, US Pat. No. 5,010,166, Toa Synthetic Research Annual Report TREND2000 No. 3 Examples thereof include a (meth) acrylic resin (polymer) synthesized by the method described in No. p42-45 and the like. In addition, in this specification, (meth) acrylic means methacrylic and acrylic.

It is preferable that the solid acrylic resin does not substantially contain a polymerization initiator, a chain transfer agent, an organic solvent and the like, which are auxiliary raw materials. Further, the acrylic resin preferably has a relatively narrow composition distribution and molecular weight distribution obtained by continuous polymerization.

As described above, the solid acrylic resin preferably contains no polymerization initiator, chain transfer agent, organic solvent, etc., which are auxiliary raw materials, that is, a resin having high purity. The purity of the solid acrylic resin (ratio of the resin contained in the resin) is preferably 95% by mass or more, more preferably 97% by mass or more.

Examples of the monomer component constituting the solid acrylic resin include (meth) acrylic acid, (meth) acrylic acid ester (alkyl ester, aryl ester, aralkyl ester, etc.), (meth) acrylamide, and (meth). Examples thereof include (meth) acrylic acid derivatives such as acrylamide derivatives.

In addition, styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinyl, together with (meth) acrylic acid and (meth) acrylic acid derivatives, are used as monomer components constituting the solid acrylic resin. Aromatic vinyl such as naphthalene may be used.

The solid acrylic resin may be a resin composed of only a (meth) acrylic component or a resin having a component other than the (meth) acrylic component as a component.
Further, the solid acrylic resin may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

Examples of plasticizers and solid resins include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Toso Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Co., Ltd., Arizona Chemical Co., Ltd., and Nikko Chemical Co., Ltd. , Nippon Catalyst Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., etc. can be used.

The rubber composition preferably contains a compound represented by the following formula (1).

In the above formula (1), R ¹¹ represents an alkyl group or an alkenyl group having 8 to 14 carbon atoms, and the alkyl group and the alkenyl group may be linear, branched or cyclic. R ¹² represents a hydroxyalkyl group or a hydroxyalkyl group having an oxyalkylene unit.

By containing the compound, the dispersibility of silica in the rubber is efficiently improved. In addition, the aggregation of silicas is suppressed, and the amount of occluder rubber wrapped in the silica aggregates can be reduced. As a result, the processability of the rubber composition, the wet grip performance, and the like are improved.

Examples of R ¹¹ include alkyl groups such as octyl group, nonyl group, isononyl group, decyl group, undecyl group, dodecyl group (lauryl group), tridecyl group and isotridecyl group; alkenyl such as octene group, nonene group and decene group. Group;

The fatty acid used as the raw material of the compound of the formula (1) is preferably lauric acid, tridecylic acid, myristic acid, coconut oil fatty acid, palm kernel oil fatty acid and the like, and the alkyl group and / or the alkenyl group are different. Coconut oil fatty acids containing two or more compounds can also be used.

Among the hydroxyalkyl groups of ^R12 or hydroxyalkyl groups having an oxyalkylene unit, the alkyl group constituting the hydroxyalkyl group is preferably a linear or branched alkyl group having 1 to 6 carbon atoms, and has 2 to 3 carbon atoms. Alkyl groups are more preferred. Further, R ¹² is preferably a group represented by the following formula (1-1).
-(R ¹³ O) _n -H (1-1)
(R ¹³ represents an alkylene group. N represents 1 to 5.)

R ¹³ is preferably an ethylene group or a propylene group, and more preferably an ethylene group. n is preferably 1 to 3, more preferably 1. The n R ^13s may be the same or different.

Specific examples of the compound represented by the formula (1) include palm kernel oil fatty acid N-methylethanolamide, palm kernel oil fatty acid N-methylethanolamide, and lauric acid N-methylethanolamide.

The content of the compound represented by the formula (1) is preferably 0.5 parts by mass or more, preferably 1.0, because it covers the silica surface and exhibits a viscosity reducing effect with respect to 100 parts by mass of the rubber component. More than parts by mass is more preferable. Further, the content of the compound is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, because it effectively suppresses thermal oxidative deterioration and does not inhibit the reaction between the rubber component and the white filler.

The rubber composition preferably contains stearic acid.
As the stearic acid, conventionally known ones can be used, and for example, products such as NOF Corporation, NOF Corporation, Kao Corporation, Wako Pure Chemical Industries, Ltd., and Chiba Fatty Acid Co., Ltd. can be used.

When stearic acid is contained, the content of stearic acid is preferably 0.5 parts by mass or more, and more preferably 1.0 part by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, and further preferably 2.5 parts by mass or less. Within the above numerical range, good wet grip performance tends to be obtained.

The rubber composition preferably contains an anti-aging agent.
Examples of the antiaging agent include naphthylamine-based antiaging agents such as phenyl-α-naphthylamine; diphenylamine-based antiaging agents such as octylated diphenylamine and 4,4'-bis (α, α'-dimethylbenzyl) diphenylamine; N. -Isopropyl-N'-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylenediamine, etc. P-Phenylenediamine-based anti-aging agent; quinoline-based anti-aging agent such as a polymer of 2,2,4-trimethyl-1,2-dihydroquinolin; 2,6-di-t-butyl-4-methylphenol, Monophenolic antioxidants such as styrenated phenol; tetrakis- [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] bis, tris, polyphenolic aging such as methane Examples include inhibitors. These may be used alone or in combination of two or more. Of these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferable, and N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1 are preferable. , 2-Dihydroquinoline polymers are more preferred.

As the anti-aging agent, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis Co., Ltd. and the like can be used.

When the anti-aging agent is contained, the content of the anti-aging agent is preferably 0.5 parts by mass or more, more preferably 0.7 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less.

The rubber composition preferably contains wax.
The wax is not particularly limited, and examples thereof include petroleum wax such as paraffin wax and microcrystalline wax; natural wax such as plant wax and animal wax; and synthetic wax such as a polymer such as ethylene and propylene. These may be used alone or in combination of two or more.

As the wax, for example, products such as Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Kagaku Co., Ltd. can be used.

When the wax is contained, the content of the wax is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less.

The rubber composition preferably contains sulfur.
Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur commonly used in the rubber industry. These may be used alone or in combination of two or more.

As the sulfur, for example, products such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Corporation, Flexis Co., Ltd., Nippon Inui Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd. can be used.

When sulfur is contained, the sulfur content is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less. When it is within the above numerical range, the above effect tends to be obtained satisfactorily.

The rubber composition preferably contains a vulcanization accelerator.
Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; tetramethylthiuram disulfide (TMTD). ), Tetrabenzyltiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N) and other thiuram-based vulcanization accelerators; N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl- 2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N, N'-diisopropyl-2-benzothiazolesulfenamide, etc. Sulfenamide-based vulcanization accelerator; guanidine-based vulcanization accelerators such as diphenylguanidine, dioltotrilguanidine, orthotrilviguanidine can be mentioned. These may be used alone or in combination of two or more. Of these, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferable.

When the vulcanization accelerator is contained, the content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less. Within the above numerical range, good wet grip performance tends to be obtained.

In addition to the above components, additives generally used in the tire industry can be added to the rubber composition, and vulcanizing agents other than sulfur (for example, organic cross-linking agents and organic peroxides); Etc. can be exemplified.

The rubber composition is produced by a general method. That is, it can be produced by a method of kneading each of the above components with a Banbury mixer, a kneader, an open roll, or the like, and then vulcanizing.

Among them, "a method for kneading a rubber material for a tire in which silica is put into a rubber material for a tire and kneaded using a Banbury mixer, which is described in Japanese Patent Application Laid-Open No. 2016-14095. A method of kneading a rubber material for a tire, which is characterized in that the material is added to the mixer in small portions. ” It is preferable to manufacture it.

In the above-mentioned kneading method for rubber materials for tires, the blending ratio is in the range of 100 to 400 parts by mass (relative to 100 parts by mass of the rubber component) of the amount of other materials added with respect to the amount of raw rubber added. It is preferable to set it as such.

The amount of silica charged into the kneader is preferably set within the range of 10 to 150 parts by mass with respect to 100 parts by mass of the rubber component. Then, while continuing the kneading of the raw rubber, silica is added in small portions.

Materials such as raw rubber, silica, and carbon black that have been charged into the kneading chamber are kneaded by the rotation of the kneading rotor, and while continuing kneading, the silica is added in small portions and repeated to knead the silica into the kneading chamber. Put everything in.

By adding the silica in small portions while kneading the raw rubber and other materials, it is possible to suppress the aggregation of silica and uniformly disperse it in the raw rubber. As a result, since the rubber material for a tire having a desired rubber physical characteristic can be stably kneaded, the disposal of the material in the tire manufacturing process can be reduced and the yield can be prevented from being lowered.

The charging speed, which is the amount of silica charged per hour, is preferably set to 5 to 15 kg / 5 sec. When it is 5 kg / 5 sec or more, good production efficiency is obtained, and when it is 15 kg / 5 sec or less, the formation of silica agglomerates tends to be suppressed.

The rubber material for tires (unvulcanized rubber composition) kneaded in the kneading chamber is discharged to the outside of the kneading chamber by opening the drop door provided at the bottom of the kneading chamber, and the kneaded product (unvulcanized rubber composition) is produced. Vulcanized rubber is produced by vulcanizing (vulcanization).

The above rubber composition is preferably used for treads (cap treads), but tire members other than treads, such as sidewalls, base treads, under treads, clinch apex, bead apex, breaker cushion rubber, and carcass cord coating. It may be used for rubber, insulation, chafers, inner liners, etc., and as a side reinforcing layer for run-flat tires.

The pneumatic tire can be manufactured by a usual method using the rubber composition.
That is, the rubber composition containing the above components is extruded according to the shape of each tire member such as a tread at the unvulcanized stage, and molded together with other tire members by a normal method on a tire molding machine. By doing so, an unvulcanized tire is formed. A tire is obtained by heating and pressurizing this unvulcanized tire in a vulcanizer. By manufacturing a tire using the rubber composition in this way, a tire having a tire member manufactured by using the rubber composition can be obtained.

The above pneumatic tires can be suitably used for passenger car tires, large passenger car tires, large SUV tires, heavy load tires such as trucks and buses, light truck tires, two-wheeled vehicle tires, run flat tires, and competition tires. Is. In particular, it can be more preferably used as a tire for passenger cars.

The present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

Hereinafter, various chemicals used in Examples and Comparative Examples will be collectively described.
SBR: Styrene butadiene rubber, Nippon Zeon Nipol 1502
NR: Natural rubber, TSR20
BR: Butadiene rubber, BR150B manufactured by Ube Industries, Ltd.
Silica 1: Carplex 67 manufactured by Degussa (N ₂ SA: 429m ² / g)
Silica 2: Zeosil 215GR manufactured by Rhodia (N ₂ SA: 250m ² / g)
Silane coupling agent: NXT-Z45 manufactured by Momentive (copolymer of bond unit A and bond unit B (bond unit A: 55 mol%, bond unit B: 45 mol%))
Carbon Black: Show Black N134 (N ₂ SA: 148m ² / g) manufactured by Cabot Japan Co., Ltd.
Zinc oxide: Zinc oxide type 2 manufactured by Mitsui Metal Mining Co., Ltd. Stearic acid: Beads stearic acid manufactured by NOF Corporation Anti-aging agent: Nocrack 6C (N- (1) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd. , 3-Dimethylbutyl) -N-phenyl-p-phenylenediamine)
Processing aid: Coconut oil Fatty acid N-methylethanolamide oil: X140 (aroma oil) manufactured by Japan Energy Co., Ltd.
Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd. 1: Noxeller CZ (N-cyclohexyl-2-benzothiazolyl sulfeneamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Vulcanization accelerator 2: Noxeller D (DPG, 1,3-diphenylguanidine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

[Examples and Comparative Examples]
A rubber material for tires (rubber composition) is kneaded using a Banbury mixer having a capacity of 270 L and a kneading rotor of 4 WN (formulation: Table 1).
The measurement and addition of silica and silane coupling agent are performed in three stages of X kneading, Y kneading, and Z kneading, and the total amount of silica and silane coupling agent added, X kneading, Y kneading, and Z kneading. The input amount of each stage is as shown in Table 1. Further, in each stage, the charging speed of the weighed silica is set to 5 kg / 5 sec, and the silica is charged in small portions.

The obtained unvulcanized rubber composition is extruded into the shape of a cap tread and bonded together with other tire members on a tire molding machine to form an unvulcanized tire, which is press-vulcanized for 20 minutes under the condition of 150 ° C. Then, a test tire (tire size: 195 / 65R15) is manufactured.

By performing the following evaluation using the test tire obtained as described above, the values in Table 1 or close to it can be obtained.

(Tensile test)
Vulcanized rubber is collected from the cap tread of the test tire to prepare a test piece, and the obtained test piece is subjected to a tensile test at 23 ° C. and 500 mm / min in accordance with JIS K6251 and stress at 100% elongation. M100 (MPa) is measured.

(Wet grip performance)
Each test tire is attached to all wheels of the vehicle (domestic FF2000cc), and the braking distance from the initial speed of 100 km / h is obtained on a wet asphalt road surface. The results are expressed as an index, and the larger the number, the better the wet skid performance (wet grip performance). The exponent is calculated by the following formula.
(Wet grip performance index) = (braking distance of Comparative Example 1) / (braking distance of each formulation) x 100

Claims (6)

A rubber composition for a tire containing a rubber component, silica and a silane coupling agent.
The blending amount A of the silica with respect to 100 parts by mass of the rubber component, the blending amount B of the silane coupling agent with respect to 100 parts by mass of the rubber component, the nitrogen adsorption specific surface area N ₂ SA of the silica, and the rubber composition for a tire. The body integral ratio φ of silica and the 100% elongation stress M100 of the vulcanized rubber of the rubber composition for tires at 23 ° C. satisfy the relationship of the following formula (I).
The blending amount A of the silica with respect to 100 parts by mass of the rubber component is 80 parts by mass or more.
The content of the silane coupling agent is 50 parts by mass or less with respect to 100 parts by mass of the silica.
A rubber composition for a tire , wherein the nitrogen adsorption specific surface area of the silica is a value measured by the BET method according to ASTM D3037-81 .
A / B / N ₂ SA / φ / M100 ≦ 0.013 (I)
(A in the formula (I) represents the blending amount (parts by mass) of silica with respect to 100 parts by mass of the rubber component, and B represents the blending amount (parts by mass) of the silane coupling agent with respect to 100 parts by mass of the rubber component. N ₂ SA represents the nitrogen adsorption specific surface area (m ² / g) of silica. φ represents the body integration ratio of silica in the rubber composition for tires. M100 represents the vulture rubber of the rubber composition for tires. Represents 100% elongation stress (MPa) at 23 ° C. The rubber composition for a tire according to claim 1, wherein the content of styrene-butadiene rubber in 100% by mass of the rubber component is 50% by mass or more. The rubber composition for a tire according to claim 1 or 2 , wherein the blending amount B of the silane coupling agent with respect to 100 parts by mass of the rubber component is 12 parts by mass or more. The rubber composition for a tire according to any one of claims 1 to 3 , wherein the silica has a nitrogen adsorption specific surface area of 300 m ² / g or more. The rubber composition for a tire according to any one of claims 1 to 4 , which is a rubber composition for a tread. A tire member using the rubber composition for a tire according to any one of claims 1 to 5 .
A pneumatic tire in which the rubber composition for a tire satisfies the formula (I).