JP7403207B2 - Rubber composition for tires and tires - Google Patents

Description

The present invention relates to a rubber composition for tires and tires.

As rubber compositions for automobile tires, rubber compositions containing conjugated diene polymers such as polybutadiene and butadiene-styrene copolymers, and fillers such as carbon black and silica are used. In recent years, with increasing interest in environmental issues, tires are required to have low fuel consumption and long life. There is a need for excellence in

Up until now, in order to improve abrasion resistance, a method has been used to compound a large amount of butadiene rubber, which has excellent abrasion resistance, but such a method leads to a decrease in the fracture characteristics of the rubber composition, leading to a decrease in wet grip performance. There was also a tendency to decrease.

On the other hand, in order to improve wet grip performance, a method has generally been taken to incorporate a large amount of filler, but it has been difficult to maintain a balance because it conflicts with low fuel consumption performance.

In addition, in addition to general fillers such as carbon black and silica, many attempts have been made to improve wet grip performance by blending special fillers such as aluminum hydroxide (for example, Patent Document 1 ), there was room for improvement in terms of balance with wear resistance performance.

Thus, it has been desired to develop a technology that maintains wet grip performance while ensuring low fuel consumption and wear resistance.

Japanese Patent Application Publication No. 2005-213353

The present invention solves the above problems and provides a rubber composition for tires that improves wear resistance while ensuring wet grip performance and low fuel consumption performance, and a tire manufactured using the rubber composition. With the goal.

The present invention includes a rubber component and a filler, the rubber component includes butadiene rubber (1), butadiene rubber (2), and natural rubber, and the butadiene rubber (1) has a cis content of 40% by mass or less, Butadiene rubber (2) has a cis content of 95% by mass or more, the content of butadiene rubber (1) in 100% by mass of the rubber component is 5 to 20% by mass, and the content of butadiene rubber (2) is 10 to 25% by mass. % by mass, and the content of the filler is 50 parts by mass or more with respect to 100 parts by mass of the rubber component.

The butadiene rubber (1) is preferably a modified butadiene rubber having a functional group that interacts with silica.

The present invention also relates to tires made using the above rubber composition.

According to the present invention, a butadiene rubber (1) having a cis content of 40% by mass or less, a butadiene rubber (2) having a cis content of 95% by mass or more, a rubber component containing natural rubber, and a filler, This tire rubber composition contains predetermined amounts of butadiene rubber (1), butadiene rubber (2), and filler, so it improves wear resistance while ensuring the wet grip performance and fuel efficiency of the tire. can be done.

The rubber composition for tires of the present invention comprises a rubber component containing a butadiene rubber (1) having a cis content of 40% by mass or less, a butadiene rubber (2) having a cis content of 95% by mass or more, natural rubber, and a filling. The content of butadiene rubber (1) is 5 to 20 mass % in 100 mass % of the rubber component, the content of butadiene rubber (2) is 10 to 25 mass %, and the filling is based on 100 parts by mass of the rubber component. The content of the agent is 50 parts by mass or more.

As mentioned above, it has been desired to develop a technology that maintains wet grip performance while ensuring low fuel consumption and wear resistance.However, these performances are contradictory to each other, so conventionally these performances have not been improved. It was difficult to improve the balance.

Generally, in a rubber composition containing a filler and a rubber component containing styrene-butadiene rubber (SBR) and butadiene rubber (BR), the filler tends to be unevenly distributed in the SBR, and compared to the SBR. It is known that BR tends to have a smaller reinforcing effect due to fillers.

Under such circumstances, the present inventors have solved the uneven distribution of fillers by using a combination of butadiene rubber with a cis content of 40% by mass or less, butadiene rubber with a cis content of 95% by mass or more, and natural rubber. It has been found that it is possible to obtain a rubber composition with as little reduction as possible. They have also found that by configuring the rubber component in this way, the reinforcing effect of the butadiene rubber filler can be increased compared to the conventional one, and a rubber composition with excellent abrasion resistance can be obtained.

In the present invention, the rubber components include butadiene rubber (1) having a predetermined amount of cis content of 40% by mass or less, butadiene rubber (2) having a predetermined amount of cis content of 95% by mass or more, and natural rubber. By using these in combination with a predetermined amount of filler, it is possible to improve wear resistance while ensuring wet grip performance and low fuel consumption. Wear performance can be improved in a well-balanced manner.

In particular, a butadiene rubber (1) having a predetermined amount of cis content of 40% by mass or less, a butadiene rubber (2) having a predetermined amount of cis content of 95% by mass or more, natural rubber, and a predetermined amount of filler. The present inventors have discovered for the first time that by using these in combination, wear resistance performance can be synergistically improved while ensuring wet grip performance and low fuel consumption performance.

It is presumed that the following mechanism is at work in producing the above effects.
When styrene-butadiene rubber (SBR), butadiene rubber (BR) with a high cis content such as 95% by mass or more, and a filler are mixed, the filler is mixed with BR, which has a relatively weak interaction with the filler. In areas where it is difficult to disperse, when BR with a low cis content such as 40% by mass or less is blended, the filler becomes easier to disperse in the BR, reinforcing the BR, and by further blending natural rubber (NR), It is presumed that the processability is improved and the dispersibility of the filler throughout the rubber can be improved, and the above-mentioned effects of the present invention can be exhibited due to these.

The rubber composition for tires of the present invention contains a rubber component containing butadiene rubber (1), butadiene rubber (2), and natural rubber.

The butadiene rubber (1) is not particularly limited as long as it has a cis content of 40% by mass or less, but the cis content of the butadiene rubber (1) is preferably 36% by mass or less, more preferably 30% by mass. The content is preferably 20% by mass or less. Moreover, it is preferably 5% by mass or more, more preferably 10% by mass or more.
In this specification, the cis content (cis 1,4 bond content) of BR can be measured by infrared absorption spectroscopy.

The vinyl content of the butadiene rubber (1) is preferably 20 mol% or less, more preferably 15 mol% or less. Note that the lower limit of the vinyl content of the butadiene rubber (1) is not particularly limited, and may be 0 mol%. Within the above range, the effects of the present invention can be more suitably obtained.
Note that in this specification, the vinyl content of BR is calculated by H ¹ -NMR measurement.

The weight average molecular weight (Mw) of the butadiene rubber (1) is preferably 300,000 or more, more preferably 400,000 or more. On the other hand, the upper limit of the weight average molecular weight of the butadiene rubber (1) is not particularly limited, but is, for example, preferably 1,000,000 or less, more preferably 900,000 or less, still more preferably 600,000 or less. Within the above range, the effects of the present invention can be more suitably obtained.
In this specification, weight average molecular weight (Mw) refers to gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKgel manufactured by Tosoh Corporation). It can be determined by standard polystyrene conversion based on the measured value by SuperMultiporeHZ-M).

The butadiene rubber (1) is not particularly limited as long as the cis content is within the predetermined range, and examples include BR with a low cis content, BR containing 1,2-syndiotactic polybutadiene crystals (SPB), and rare earth element-based BR. Those commonly used in the tire industry, such as butadiene rubber (rare earth BR) synthesized using a catalyst, can be used. Furthermore, tin-modified butadiene rubber (tin-modified BR) modified with a tin compound can also be used. These may be used alone or in combination of two or more.

As the rare earth BR, conventionally known ones can be used, for example, rare earth element catalysts (lanthanum series rare earth element compounds, organic aluminum compounds, aluminoxane, halogen-containing compounds, catalysts containing Lewis bases as necessary), etc. (For example, butadiene rubber (Nd-based BR) synthesized using a neodymium-based catalyst using a neodymium (Nd)-containing compound).

As the butadiene rubber (1), for example, products manufactured by Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, LANXESS Corporation, etc. can be used.

Further, the butadiene rubber (1) may be unmodified BR or modified BR.
Examples of modified BR include BR having a functional group that interacts with fillers such as silica; for example, terminal-modified BR in which at least one end of BR is modified with a compound (modifier) having the following functional group. (Terminally modified BR having the following functional group at the end), main chain modified BR having the following functional group in the main chain, main chain terminal modified BR having the following functional group in the main chain and the end (for example, main chain modified BR having the following functional group in the main chain) Main chain terminal modified BR) which has a functional group and at least one end is modified with a compound (modifier) having the following functional group, or a polyfunctional compound having two or more epoxy groups in the molecule ( Examples include terminal-modified BR in which a hydroxyl group or an epoxy group is introduced. Alternatively, the main chain and/or terminal end of the rubber may be modified with a polyfunctional modifier such as tin tetrachloride or silicon tetrachloride to have a partially branched structure.

Among these, it is particularly preferable that the main chain and/or terminal (more preferably terminal) of the butadiene rubber (1) be modified with a modifier having a functional group that interacts with silica. By using a modified butadiene rubber that has been modified with such a modifier and has a functional group that interacts with silica as the butadiene rubber (1), the dispersibility of the filler in BR can be further improved, resulting in excellent wet grip performance. and wear resistance performance in a well-balanced manner. Thus, it is also one of the preferred embodiments of the present invention that the butadiene rubber (1) is a modified butadiene rubber having a functional group that interacts with silica.

Examples of the functional group that interacts with the silica include an amino group (preferably an amino group in which the hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an amide group, a silyl group, an alkoxysilyl group. (preferably an alkoxysilyl group having 1 to 6 carbon atoms), isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, oxycarbonyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, sulfinyl group , thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), hydrocarbon group, hydroxyl group, Examples include oxy group and epoxy group. Note that these functional groups may have a substituent. Among these, primary, secondary, and tertiary amino groups (especially glycidylamino groups), epoxy groups, hydroxyl groups, and alkoxy groups (preferably carbon atoms 1 to 6) are highly effective in improving fuel efficiency and wet grip performance. (alkoxy group), an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms), and a hydrocarbon group.

The modified butadiene rubber having a functional group that interacts with silica is preferably a butadiene rubber (S-modified BR) modified with a compound (modifier) represented by the following formula (1).

In the above formula (1), R ¹ , R ² and R ³ are the same or different and are an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or any of these groups. Represents a derivative. R ⁴ and R ⁵ are the same or different and represent a hydrogen atom or an alkyl group. R ⁴ and R ⁵ may be combined to form a ring structure together with the nitrogen atom. n represents an integer.

Examples of the above-mentioned S-modified BR include those described in JP-A-2010-111753, etc. Among them, the polymerization end (active end) of butadiene rubber is modified with a compound represented by the above formula (1). butadiene rubber is preferably used.

In the above formula (1), R ¹ , R ² and R ³ are preferably alkoxy groups (preferably 1 to 8 carbon atoms, more preferably (alkoxy group having 1 to 4 carbon atoms). As R ⁴ and R ⁵ , an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is suitable. n is preferably 1 to 5, more preferably 2 to 4, and still more preferably 3. Furthermore, when R ⁴ and R ⁵ combine to form a ring structure together with a nitrogen atom, it is preferably a 4- to 8-membered ring. Note that the alkoxy group also includes a cycloalkoxy group (cyclohexyloxy group, etc.) and an aryloxy group (phenoxy group, benzyloxy group, etc.). By using preferred compounds, the effects of the present invention can be better obtained.

Specific examples of the compound represented by the above formula (1) include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, and 3-dimethylaminopropyltriethoxysilane. Examples include silane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. Among these, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropyltriethoxysilane, and 3-diethylaminopropyltrimethoxysilane are preferable because they can better improve the above-mentioned performance. These may be used alone or in combination of two or more.

Another preferable example of the modified butadiene rubber having a functional group that interacts with silica is a butadiene rubber modified with a compound (modifier) represented by the following formula (2).

In the above formula (2), R is the same or different and represents a monovalent hydrocarbon group having 1 to 30 carbon atoms. X ² is the following formula:

(In the formula, R ¹¹ and R ¹² are the same or different and represent a divalent hydrocarbon group. R ¹³ represents a cyclic ether group.) ^X3 is the following formula:

(In the formula, R ²¹ represents an alkylene group or an alkylarylene group having 2 to 10 carbon atoms. ^{R 22} represents a hydrogen atom or a methyl group. R ²³ represents an alkoxy group or aryloxy group having 1 to 10 carbon atoms. .t is an integer from 2 to 20). a, b, and c represent the number of repeats of each repeating unit.

Among the butadiene rubbers modified with the compound (modifier) represented by the above formula (2), the polymerization end (active end) of the butadiene rubber is modified with the compound represented by the above formula (2). Butadiene rubber is preferably used.

In the above formula (2), R is the same or different and represents a monovalent hydrocarbon group having 1 to 30 carbon atoms, and the monovalent hydrocarbon group may be linear, branched, or cyclic. Any of them may be used, and examples thereof include aliphatic hydrocarbon groups having 1 to 30 carbon atoms, alicyclic hydrocarbon groups having 3 to 30 carbon atoms, and aromatic hydrocarbon groups having 6 to 30 carbon atoms. Among these, aliphatic hydrocarbon groups having 1 to 30 carbon atoms are preferred because they provide excellent fuel efficiency and fracture properties. More preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms, still more preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms, particularly preferably an aliphatic hydrocarbon group having 1 to 3 carbon atoms. Preferred examples of the above R include an alkyl group having the above number of carbon atoms, and specifically, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group. , tert-butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, octadecyl group, etc. . Among these, a methyl group is particularly preferred since it provides excellent fuel efficiency and fracture properties.

R ¹¹ and R ¹² in X ² in the above formula (2) are the same or different and represent a divalent hydrocarbon group, such as a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched Alternatively, examples thereof include an unbranched alkenylene group having 2 to 30 carbon atoms, a branched or unbranched alkynylene group having 2 to 30 carbon atoms, and an arylene group having 6 to 30 carbon atoms. Among these, branched or unbranched alkylene groups having 1 to 30 carbon atoms are preferred. More preferably a branched or unbranched alkylene group having 1 to 15 carbon atoms, still more preferably a branched or unbranched alkylene group having 1 to 5 carbon atoms, particularly preferably an unbranched alkylene group having 1 to 3 carbon atoms. . Preferred examples of R ¹¹ and R ¹² include alkylene groups having the above carbon numbers, and specifically, methylene groups, ethylene groups, propylene groups, isopropylene groups, butylene groups, isobutylene groups, pentylene groups, Examples include hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, octadecylene group, and the like. Among these, methylene group, ethylene group, and propylene group are particularly preferred since they provide excellent fuel efficiency and fracture properties.

R ¹³ in X ² in the above formula (2) represents a cyclic ether group, and examples of the cyclic ether group include an oxirane group, an oxetane group, an oxolane group, an oxane group, an oxepane group, an oxocane group, and an oxonane group. Cyclic ether groups having one ether bond such as oxecane group, oxet group, oxole group, cyclic ether group having two ether bonds such as dioxolane group, dioxane group, dioxepane group, dioxecan group, ethers such as trioxane group Examples include a cyclic ether group having three bonds. Among these, a cyclic ether group having 2 to 7 carbon atoms having one ether bond is preferred, a cyclic ether group having 2 to 5 carbon atoms having one ether bond is more preferred, and an oxirane group is even more preferred. Moreover, it is preferable that the cyclic ether group does not have an unsaturated bond in the ring skeleton. Further, the hydrogen atom of the above-mentioned cyclic ether group may be substituted with the above-mentioned monovalent hydrocarbon group.

In X ³ in the above formula (2), R ²¹ represents an alkylene group having 2 to 10 carbon atoms or an alkylarylene group, and among them, a branched or unbranched alkylene group having 2 to 8 carbon atoms is preferable, and a branched Alternatively, an unbranched alkylene group having 2 to 6 carbon atoms is more preferred, a branched or unbranched alkylene group having 2 to 4 carbon atoms is even more preferred, and a branched or unbranched alkylene group having 3 carbon atoms is particularly preferred. Preferred examples of R ²¹ include alkylene groups having the above-mentioned number of carbon atoms, specifically, ethylene group, propylene group, isopropylene group, butylene group, isobutylene group, pentylene group, hexylene group, heptylene group, Examples include octylene group, nonylene group, and decylene group. Among these, ethylene group, propylene group, isopropylene group, butylene group, and isobutylene group are particularly preferred, and propylene group and isopropylene group are most preferred.

R ²² in X ³ in the above formula (2) represents a hydrogen atom or a methyl group, and is particularly preferably a hydrogen atom.

R ²³ in X ³ in the above formula (2) represents an alkoxy group having 1 to 10 carbon atoms or an aryloxy group, and among them, a branched or unbranched alkoxy group having 1 to 8 carbon atoms is preferable, and a branched or an unbranched alkoxy group having 1 to 6 carbon atoms is more preferred, and a branched or unbranched alkoxy group having 1 to 4 carbon atoms is even more preferred. Preferred examples of the above ^R23 include alkoxy groups having the above-mentioned number of carbon atoms, and specifically, methoxy groups, ethoxy groups, propoxy groups, isopropoxy groups, butoxy groups, isobutoxy groups, pentyloxy groups, hexyloxy groups, Examples include heptyloxy group and octyloxy group. Among these, methoxy group, ethoxy group, propoxy group, and butoxy group are particularly preferred, and methoxy group is most preferred.

In X ³ in the above formula (2), t is an integer from 2 to 20, with t from 2 to 8 being particularly preferred.

As the compound represented by the above formula (2), a compound represented by the following formula (3) is preferably used because it can better improve the above-mentioned performance.

Methods for modifying butadiene rubber using the compound represented by the above formula (1) or the compound (modifier) represented by the above formula (2) include Japanese Patent Publication No. 6-53768, Japanese Patent Publication No. 6-57767, etc. Conventionally known techniques can be used, such as the method described in . For example, it can be modified by bringing butadiene rubber into contact with the compound. Specifically, after preparing butadiene rubber by anionic polymerization using a polymerization initiator such as a lithium compound, a predetermined amount of the compound is added to the rubber solution. Examples include a method in which the compound is added and the polymerization end (active end) of butadiene rubber is reacted with the compound.

The content of the butadiene rubber (1) is 5 to 20% by mass in 100% by mass of the rubber component. When the content of the butadiene rubber (1) is within such a range, wear resistance performance can be improved while ensuring wet grip performance and low fuel consumption performance. The content is preferably 7% by mass or more, more preferably 10% by mass or more, even more preferably 12% by mass or more. Moreover, it is preferably 17% by mass or less, more preferably 15% by mass or less.

The butadiene rubber (2) is not particularly limited as long as it has a cis content of 95% by mass or more, but the cis content of the butadiene rubber (2) is preferably 97% by mass or more. Note that the upper limit is not particularly limited.

The vinyl content of the butadiene rubber (2) is preferably 20 mol% or less, more preferably 15 mol% or less, even more preferably 10 mol% or less, even more preferably 5 mol% or less, particularly preferably 3 mol% or less. It is. Note that the lower limit of the vinyl content of the butadiene rubber (2) is not particularly limited, and may be 0 mol%. Within the above range, the effects of the present invention can be more suitably obtained.

The weight average molecular weight (Mw) of the butadiene rubber (2) is preferably 300,000 or more, more preferably 400,000 or more. On the other hand, the upper limit of the weight average molecular weight of the butadiene rubber (2) is not particularly limited, but is, for example, preferably 1,000,000 or less, more preferably 900,000 or less, still more preferably 600,000 or less. Within the above range, the effects of the present invention can be more suitably obtained.

The butadiene rubber (2) is not particularly limited as long as the cis content is within the predetermined range, and examples include BR with a high cis content, BR containing 1,2-syndiotactic polybutadiene crystals (SPB), and rare earth element-based BR. Those commonly used in the tire industry, such as butadiene rubber (rare earth BR) synthesized using a catalyst, can be used. Furthermore, tin-modified butadiene rubber (tin-modified BR) modified with a tin compound can also be used. These may be used alone or in combination of two or more.

As the butadiene rubber (2), for example, products manufactured by Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, LANXESS Corporation, etc. can be used.

Further, the butadiene rubber (2) may be unmodified BR or modified BR. The modified BR is the same as described above.

The content of the butadiene rubber (2) is 10 to 25% by mass in 100% by mass of the rubber component. When the content of the butadiene rubber (2) is within this range, wear resistance can be improved while ensuring wet grip performance and low fuel consumption performance. The content is preferably 12% by mass or more, more preferably 15% by mass or more. Further, it is preferably 22% by mass or less, more preferably 20% by mass or less, and even more preferably 17% by mass or less.

Although the content ratio of the butadiene rubber (1) and the butadiene rubber (2) in the rubber component (butadiene rubber (1)/butadiene rubber (2)) is not particularly limited, From the viewpoint of balance with grip performance, 0.2/1 to 2/1 is preferable, 0.5/1 to 1.5/1 is more preferable, and 0.7/1 to 1.2/1 is particularly preferable. .

Note that the cis content of the butadiene rubber can be adjusted by the type of catalyst (polymerization initiator) used during polymerization. For example, a Ziegler-Natta catalyst can be used to produce butadiene rubber with a high cis content, and a lithium compound (lithium catalyst) such as alkyllithium or aryllithium can be used to produce butadiene rubber with a low cis content. can be manufactured.

The natural rubber (NR) to be blended into the rubber component is not particularly limited, and for example, those commonly used in the tire industry, such as TSR20 and RSS#3, can be used. Modified natural rubbers such as deproteinized natural rubber (DPNR), high purity natural rubber (UPNR), epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber can also be used. . By blending NR, the reinforcing properties of NR itself are added, and wear resistance and fuel efficiency can be improved in a well-balanced manner.

In order to more preferably obtain the effects of the present invention, the content of NR is preferably 5% by mass or more, more preferably 7% by mass or more, still more preferably 10% by mass out of 100% by mass in the rubber component. That's all. Further, it is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, particularly preferably 15% by mass or less.

In addition to butadiene rubber (1), butadiene rubber (2), and natural rubber, the rubber component may further contain other rubber components.

Examples of the other rubber components include isoprene rubber (IR), epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, styrene-butadiene rubber (SBR), the above-mentioned butadiene rubber (1), or the above-mentioned butadiene rubber (2). ) other than diene rubbers such as butadiene rubber (BR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), ethylene propylene diene rubber (EPDM), butyl rubber (IIR), halogenated Examples include non-diene rubber such as butyl rubber (X-IIR). These may be used alone or in combination of two or more. Among these, it is preferable that the rubber component contains SBR as another rubber component because good fuel efficiency and wet grip performance can be obtained.
In the tire rubber composition of the present invention, even when SBR is blended, butadiene rubber with a cis content of 40% by mass or less, butadiene rubber with a cis content of 95% by mass or more, and natural rubber are combined. By using the filler in combination, the uneven distribution of the filler in the SBR can be sufficiently reduced, and the reinforcing effect of the butadiene rubber filler can be increased, so good wear resistance performance can be obtained, and the present invention Good effects can be obtained.

SBR can be prepared by appropriately setting the blend of raw material monomers such as styrene and 1,3-butadiene, and using known methods such as emulsion polymerization, solution polymerization, and anionic polymerization. For example, emulsion polymerization SBR (E-SBR), solution polymerized SBR (S-SBR), and other materials commonly used in the tire industry can be used. These may be used alone or in combination of two or more.

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

Further, the SBR may be non-denatured SBR or modified SBR. Examples of the modified SBR include modified SBR into which functional groups similar to those of the modified BR described above have been introduced.

Among these, it is particularly preferable that the main chain and/or the terminal (more preferably the terminal) of the SBR be modified with a modifier having a functional group that interacts with silica. By using a modified styrene-butadiene rubber that has been modified with such a modifier and has a functional group that interacts with silica, particularly excellent fuel efficiency and wet grip performance can be obtained. Thus, it is also one of the preferred embodiments of the present invention that the rubber component contains SBR, and the SBR is a modified styrene-butadiene rubber having a functional group that interacts with silica.

The styrene-butadiene rubber modified with a modifier having a functional group that interacts with silica is a styrene-butadiene rubber that is a backbone component of the butadiene rubber modified with a modifier that has a functional group that interacts with silica. You can use a substitute for butadiene rubber. Among them, the modified styrene-butadiene rubber having a functional group that interacts with silica is styrene-butadiene rubber modified with the compound (modifier) represented by the formula (1) (S-modified SBR), or the above-mentioned Styrene-butadiene rubber modified with a compound (modifier) represented by formula (2) is preferred. For example, as a styrene-butadiene rubber (S-modified S-SBR) in which the polymerization end (active end) of solution-polymerized styrene-butadiene rubber (S-SBR) is modified with a compound represented by the above formula (1), Examples include those described in Publication No. 2010-111753.

As a method for modifying styrene-butadiene rubber with the compound represented by the above formula (1) or the compound (modifier) represented by the above formula (2), conventionally known methods can be used. For example, styrene-butadiene rubber and It can be modified by contacting it with a compound. Specifically, after preparing styrene-butadiene rubber by solution polymerization, a predetermined amount of the compound is added to the rubber solution, and the polymerization end (active end) of the styrene-butadiene rubber is reacted with the compound. .

As the SBR, oil-extended SBR or non-oil-extended SBR may be used. When using oil-extended SBR, the amount of oil-extended SBR, that is, the content of oil-extended oil contained in SBR, should be, for example, 10 to 50 parts by mass per 100 parts by mass of the rubber solid content of SBR. Can be done.

The styrene content of SBR is preferably 15% by mass or more, more preferably 20% by mass or more. Moreover, it is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less. When the styrene content is within the above range, good fuel efficiency tends to be achieved.
Note that in this specification, the styrene content of SBR is calculated by H ¹ -NMR measurement.

The vinyl content of SBR is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 25 mol% or more, even more preferably 30 mol% or more. Moreover, it is preferably 70 mol% or less, more preferably 60 mol% or less, and still more preferably 50 mol% or less. When the vinyl content is within the above range, good wear resistance performance tends to be obtained.
In this specification, the vinyl content of SBR refers to the vinyl content of the butadiene moiety (the number of vinyl group units in the butadiene structure), and is calculated by H ¹ -NMR measurement.

The weight average molecular weight (Mw) of SBR is preferably 200,000 or more, more preferably 250,000 or more, even more preferably 300,000 or more, and particularly preferably 900,000 or more. Moreover, 2 million or less is preferable, and 1.8 million or less is more preferable. When the weight average molecular weight is within the above range, good processability, low fuel consumption performance, and wear resistance performance tend to be obtained.

The content of SBR is preferably 40% by mass or more, more preferably 45% by mass or more, and still more preferably 50% by mass out of 100% by mass of the above rubber component, from the viewpoint of fuel efficiency, wet grip performance, and abrasion resistance. That's all. Moreover, it is preferably 80% by mass or less, more preferably 75% by mass or less, still more preferably 70% by mass or less, even more preferably 65% by mass or less.

The rubber composition for tires of the present invention contains a filler. As the filler, those commonly used as fillers in the tire industry, such as silica, carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica, can be used. Among these, by blending silica as a filler, a reinforcing effect is obtained, fuel efficiency and wet grip performance are improved, and the effects of the present invention can be favorably obtained. Furthermore, the effects of the present invention can be more suitably obtained by using silica and carbon black together as fillers. In this way, a form in which a filler containing silica is blended is also one of the preferred embodiments of the present invention. Furthermore, a form in which a filler containing silica and carbon black is blended is also one of the preferred embodiments of the present invention.

The content of the filler (that is, the total content of fillers such as silica and carbon black) is 50 parts by mass or more based on 100 parts by mass of the rubber component. When the content of the filler is within this range, wear resistance can be improved while ensuring wet grip performance and low fuel consumption performance. The content of the filler is preferably 55 parts by mass or more, more preferably 60 parts by mass or more, based on 100 parts by mass of the rubber component. Moreover, it is preferably 90 parts by mass or less, more preferably 85 parts by mass or less, and even more preferably 80 parts by mass or less.

As described above, the rubber composition of the present invention preferably contains silica, and the content of silica is preferably 30 parts by mass or more based on 100 parts by mass of the rubber component. When the silica content is within this range, fuel efficiency and wet grip performance are better. More preferably 40 parts by mass or more, still more preferably 50 parts by mass or more, particularly preferably 55 parts by mass or more. Further, it is preferably 90 parts by mass or less, more preferably 85 parts by mass or less, still more preferably 80 parts by mass or less, particularly preferably 70 parts by mass or less.

The silica is not particularly limited, and for example, dry process silica (anhydrous silica), wet process silica (hydrous silica), colloidal silica, precipitated silica, calcium silicate, aluminum silicate, etc. can be used. Wet process silica (hydrated silica) is preferable because it has a large amount of silica. These silicas may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 50 m ² /g or more, more preferably 100 m ² /g or more, even more preferably 150 m ² /g or more. By setting it above the lower limit, good wear resistance performance and wet grip performance can be obtained. Moreover, it is preferably 250 m ² /g or less, more preferably 200 m ² /g or less, and still more preferably 180 m ² /g or less. By keeping it below the upper limit, good fuel efficiency can be obtained.
Note that the N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-93.

As the silica, for example, products manufactured by Degussa, Rhodia, Tosoh Silica, Solvay Japan, Tokuyama, etc. can be used.

When the rubber composition of the present invention contains silica, it preferably contains a silane coupling agent together with the silica.
As the silane coupling agent, any silane coupling agent conventionally used in combination with silica in the rubber industry can be used, and is not particularly limited. For example, bis(3-triethoxysilylpropyl)tetrasulfide, bis (2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(4-trimethoxysilylethyl)tetrasulfide, -Trimethoxysilylbutyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-triethoxysilylbutyl)trisulfide, bis(3-trisulfide) methoxysilylpropyl) trisulfide, bis(2-trimethoxysilylethyl) 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-tri Methoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 2- Trimethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3 - Sulfide series such as trimethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, NXT manufactured by Momentive , mercapto-based such as NXT-Z, vinyl-based such as vinyltriethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltri Amino-based such as ethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxy Silane, glycidoxy type such as γ-glycidoxypropylmethyldimethoxysilane, nitro type such as 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxy Examples include chloro-based silane, 2-chloroethyltrimethoxysilane, and 2-chloroethyltriethoxysilane. These may be used alone or in combination of two or more. Among these, sulfide-based and mercapto-based are preferred because the effects of the present invention can be better obtained.

As the silane coupling agent, for example, products manufactured by Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used.

When the rubber composition of the present invention contains a silane coupling agent, the content of the silane coupling agent is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass, based on 100 parts by mass of silica. The amount is more preferably 2.5 parts by mass or more. By setting the amount above the lower limit, there is a tendency for the effect obtained by blending the silane coupling agent to be obtained. Moreover, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 10 parts by mass or less. By setting the amount below the upper limit, an effect commensurate with the blending amount can be obtained, and good processability during kneading tends to be obtained.

Examples of carbon black include, but are not limited to, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, and the like. These may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 5 m ² /g or more, more preferably 50 m ² /g or more, and even more preferably 80 m ² /g or more. By setting it above the lower limit, good abrasion resistance and wet grip performance tend to be obtained. Further, the area is preferably 200 m ² /g or less, more preferably 150 m ² /g or less, and even more preferably 130 m ² /g or less. When the content is below the upper limit, good dispersion of carbon black is likely to be obtained, and good wear resistance, wet grip performance, and fuel efficiency tend to be obtained.
In this specification, the nitrogen adsorption specific surface area of carbon black is determined according to JIS K 6217-2:2001.

The amount of dibutyl phthalate (DBP) absorbed by carbon black is preferably 5 ml/100 g or more, more preferably 80 ml/100 g or more, and even more preferably 100 ml/100 g or more. By setting the amount above the lower limit, a sufficient reinforcing effect can be obtained, and good wear resistance and fracture properties tend to be obtained. Further, the amount is preferably 300 ml/100 g or less, more preferably 180 ml/100 g or less, and even more preferably 140 ml/100 g or less. When the content is below the upper limit, dispersibility becomes good, and good fuel efficiency and processability tend to be obtained.
Note that in this specification, the DBP absorption amount of carbon black is measured in accordance with ASTM D2414-93.

Examples of carbon black include Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Nippon Kayaku Carbon Co., Ltd., Columbia Carbon Co., Ltd., and Degussa Co., Ltd. You can use products such as

When the rubber composition of the present invention contains carbon black, the content of carbon black is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass, based on 100 parts by mass of the rubber component. Parts by mass or more. By setting it above the lower limit, sufficient reinforcing properties can be obtained, and good abrasion resistance and wet grip performance tend to be obtained. Moreover, it is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. There is a tendency for good fuel efficiency performance to be obtained by keeping it below the upper limit.

In addition to the above-mentioned components, the rubber composition of the present invention also includes plasticizers such as extender oil and liquid resin; vulcanizing agents such as sulfur and organic crosslinking agents; thiazole-based vulcanization accelerators and thiuram-based vulcanization agents. Vulcanization accelerators such as accelerators, sulfenamide-based vulcanization accelerators, and guanidine-based vulcanization accelerators; vulcanization activators such as stearic acid and zinc oxide; dicumyl peroxide, ditertiary butyl peroxide, etc. Compounding agents conventionally used in the rubber industry such as organic peroxides; processing aids; anti-aging agents; waxes; lubricants can be used.

From the viewpoint of processability, the rubber composition of the present invention preferably contains a plasticizer such as oil or liquid resin. Among these, the rubber composition preferably contains oil as a plasticizer. This makes it possible to adjust the hardness to an appropriately low level and obtain good workability, wet grip performance, and fracture characteristics.

The oil is not particularly limited, and includes, for example, process oil, vegetable oil, or a mixture thereof. As the process oil, for example, paraffinic process oil, aromatic process oil, naphthenic process oil, etc. can be used. Vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, Examples include olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These may be used alone or in combination of two or more. Among these, aroma process oils are preferred because the effects of the present invention can be suitably obtained.

Examples of the oil include Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu Co., Ltd., and Fuji Kosan Co., Ltd. You can use products such as

Note that, from an environmental standpoint, the polycyclic aromatic content (PCA) of the oil 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 Institute method 346/92.

The rubber composition may also contain a liquid resin as a plasticizer. By including a liquid resin as a plasticizer, fuel efficiency, breaking properties, and wet grip performance can be improved.

The liquid resin is not particularly limited, and examples thereof include aromatic vinyl polymers, coumaron indene resins, indene resins, terpene resins, and rosin resins. These may be used alone or in combination of two or more. Among these, aromatic vinyl polymers, coumaron indene resins, terpene resins, rosin resins, and derivatives thereof are preferred, and coumaron indene resins are more preferred, from the viewpoint of fuel efficiency and fracture characteristics.

The above-mentioned aromatic vinyl polymer is a resin obtained by polymerizing α-methylstyrene and/or styrene, such as a homopolymer of styrene, a homopolymer of α-methylstyrene, or a combination of α-methylstyrene and styrene. Examples include copolymers.
The above-mentioned coumaron indene resin is a resin containing coumaron and indene as main monomer components constituting the skeleton (main chain) of the resin, and other monomer components that may be included in the skeleton other than coumaron and indene are: , styrene, α-methylstyrene, methylindene, vinyltoluene, etc.
The above-mentioned indene resin is a resin containing indene as a main monomer component constituting the skeleton (main chain) of the resin.
The above-mentioned terpene resins include resins obtained by polymerizing terpene compounds such as α-pinene, β-pinene, camphor, and dipetene, and terpenes such as terpenephenol, which is a resin obtained from terpene compounds and phenolic compounds as raw materials. It is a type resin.
The above-mentioned rosin resin is a rosin-based resin typified by natural rosin, polymerized rosin, modified rosin, ester compounds thereof, or hydrogenated products thereof.

The softening point of the liquid resin is preferably -40°C or higher, more preferably -20°C or higher, even more preferably -10°C or higher, and particularly preferably 0°C or higher. Further, the softening point is preferably 45°C or lower, more preferably 40°C or lower, and even more preferably 35°C or lower. When the softening point of the liquid resin is within the above range, the effects of improving wet grip performance and breaking characteristics can be more suitably obtained.
In this specification, the softening point is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2001 is measured using a ring and ball softening point measuring device.

When the rubber composition of the present invention contains a plasticizer, the content of the plasticizer is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and 10 parts by mass or more based on 100 parts by mass of the rubber component. More preferred. Further, it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. When the content of the plasticizer is within such a range, the effects of the present invention can be more suitably obtained.

The rubber composition of the present invention preferably contains wax.
The wax is not particularly limited, and includes petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as vegetable waxes and animal waxes; and synthetic waxes such as polymers of ethylene and propylene. These may be used alone or in combination of two or more. Among these, petroleum wax is preferred, and paraffin wax is more preferred.

From the viewpoint of the performance balance, the wax content is preferably 1 to 20 parts by mass, more preferably 1.5 to 10 parts by mass, based on 100 parts by mass of the rubber component.

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

From the viewpoint of the performance balance, the content of the anti-aging agent is preferably 1 to 10 parts by weight, more preferably 2 to 7 parts by weight, based on 100 parts by weight of the rubber component.

As the anti-aging agent, for example, products manufactured by Seiko Kagaku Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Kagaku Kogyo Co., Ltd., Flexis Co., Ltd., etc. can be used.

The rubber composition of the present invention preferably contains stearic acid. From the viewpoint of the performance balance, the content of stearic acid is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, based on 100 parts by mass of the rubber component.

As the stearic acid, conventionally known ones can be used, and for example, products from NOF Corporation, NOF, Kao Corporation, Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used. .

The rubber composition of the present invention preferably contains zinc oxide.
As zinc oxide, conventionally known ones can be used, such as products from Mitsui Kinzoku Kogyo Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

When the rubber composition of the present invention contains zinc oxide, the content of zinc oxide is preferably 1.0 parts by mass or more, more preferably 2.0 parts by mass or more, based on 100 parts by mass of the rubber component. be. Moreover, the said content becomes like this. Preferably it is 3.7 mass parts or less, More preferably, it is 3.0 mass parts or less. Within the above numerical range, sufficient hardness is obtained and the effects of the present invention tend to be better obtained.

The rubber composition of the present invention preferably contains sulfur.
From the viewpoint of the performance balance, the sulfur content is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, and still more preferably 1 to 3 parts by mass, based on 100 parts by mass of the rubber component. It is.

Sulfur includes powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc. commonly used in the rubber industry. These may be used alone or in combination of two or more.

As the sulfur, for example, products manufactured by Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis, Nippon Karidome Kogyo Co., Ltd., Hosoi Chemical Co., Ltd., etc. can be used. .

The rubber composition of the present invention preferably contains a vulcanization accelerator.
From the viewpoint of the performance balance, the content of the vulcanization accelerator is preferably 1 to 10 parts by weight, more preferably 2 to 7 parts by weight, based on 100 parts by weight of the rubber component.

Examples of vulcanization accelerators include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; tetramethylthiuram disulfide (TMTD); ), thiuram-based vulcanization accelerators such as tetrabenzylthiuram disulfide (TBzTD), tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); N-cyclohexyl-2-benzothiazolesulfenamide, N-t-butyl- 2-Benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N,N'-diisopropyl-2-benzothiazolesulfenamide, etc. Examples include sulfenamide vulcanization accelerators; guanidine vulcanization accelerators such as N,N'-diphenylguanidine, diorthotolylguanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more. Among these, from the viewpoint of the performance balance, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferred.

The rubber composition of the present invention is manufactured by a conventional method. That is, it can be produced by kneading the above-mentioned components using a Banbury mixer, kneader, open roll, etc., and then vulcanizing the mixture.

As for the kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and the vulcanization accelerator are kneaded, the kneading temperature is usually 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30°C. The time is from seconds to 30 minutes, preferably from 1 minute to 30 minutes. In the final kneading step of kneading the vulcanizing agent and vulcanization accelerator, the kneading temperature is usually 100°C or less, preferably room temperature to 80°C. Further, a composition obtained by kneading a vulcanizing agent and a vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 120 to 200°C, preferably 140 to 180°C.

The rubber composition of the present invention is suitably used for treads (cap treads), but also for members other than treads, such as sidewalls, base treads, undertreads, clinch apex, bead apex, breaker cushion rubber, carcass cords. It may be used for coating rubber, insulation, chafer, inner liner, etc., and for side reinforcement layers of run-flat tires.

The tire of the present invention is manufactured by a conventional method using the above rubber composition. That is, a rubber composition containing the above components is extruded in the unvulcanized stage to match the shape of each tire component such as a tread, and then molded together with other tire components using 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.

The tire of the present invention may be either a pneumatic tire or an airless (solid) tire, but is preferably a pneumatic tire. Further, the tire of the present invention is suitably used as a tire for a passenger car, a tire for a truck or a bus, a tire for two-wheeled vehicles, a tire for racing, etc., and is particularly suitably used as a tire for a passenger car.

The present invention will be specifically explained based on examples, but the present invention is not limited to these examples.

The physical properties of the polymer produced below were measured as follows.

[Weight average molecular weight (Mw)]
The weight average molecular weight (Mw) was measured by gel permeation chromatography (GPC) under the following conditions (1) to (8).
(1) Equipment: GPC-8000 series manufactured by Tosoh Corporation (2) Separation column: TSKgel SuperMultiporeHZ-M manufactured by Tosoh Corporation
(3) Measurement temperature: 40℃
(4) Carrier: Tetrahydrofuran (5) Flow rate: 0.6 mL/min (6) Injection volume: 5 μL
(7) Detector: Differential refractometer (8) Molecular weight standard: Standard polystyrene

[Vinyl content and styrene content]
The measurement was carried out by H ¹ -NMR measurement using a JNM-ECA series NMR apparatus manufactured by JEOL Ltd.

[Cis content]
The cis content (cis 1,4 bond content) was measured by infrared absorption spectrometry using Spectrum one manufactured by PerkinElmer Co., Ltd.

<Manufacture example 1 (SBR)>
After charging 6000 g of cyclohexane, 150 g of styrene, 450 g of 1,3-butadiene, and tetramethylethylenediamine in an amount equivalent to 1.5 times the molar amount of n-butyllithium used in an autoclave equipped with a stirrer, 9.0 g of n-butyllithium was added. 5 mmol was added and polymerization was started at 50°C. After 20 minutes from the start of polymerization, a mixture of 60 g of styrene and 340 g of 1,3-butadiene was continuously added over 60 minutes. The maximum temperature during the polymerization reaction was 70°C.
After the continuous addition was completed, the polymerization reaction was continued for another 40 minutes, and after confirming that the polymerization conversion rate was 100%, a small amount of the polymerization solution was sampled. A small amount of the sampled polymer solution was added with excess methanol to stop the reaction, and then air-dried to obtain a polymer, which was used as a sample for gel permeation chromatography analysis.
Immediately after sampling a small amount of the polymerization solution, an amount of polyorganosiloxane A (a compound represented by the following formula (3), edited by the Chemical Society of Japan, 4th edition) corresponding to 0.03 times the mole of n-butyllithium used was ) was added in the form of a 10% toluene solution and reacted for 30 minutes. - Methanol in an amount equivalent to twice the molar amount of butyllithium was added to obtain a polymerization solution containing conjugated diene rubber I. After adding 0.2 parts by mass of Irganox 1520 (manufactured by Ciba Geigy) as an anti-aging agent to the above polymerization solution per 100 parts by mass of the rubber content, the polymerization solvent was removed by steam stripping, and 60 parts by mass of the polymerization solvent was removed by steam stripping. It was vacuum-dried at ℃ for 24 hours to obtain solid SBR1. As a result of the analysis, the styrene content of the obtained SBR1 was 42% by mass. The Mw was about 1 million and the vinyl content was 32 mol%.

<Preparation of terminal modifier>
Under a nitrogen atmosphere, 23.6 g of 3-(N,N-dimethylamino)propyltrimethoxysilane (3-dimethylaminopropyltrimethoxysilane) (manufactured by Azumax Co., Ltd.) was placed in a 100 ml volumetric flask, and anhydrous hexane (Kanto (manufactured by Kagaku Co., Ltd.) was added to make the total volume 100 ml.

<Manufacture example 2 (BR)>
18 L of n-hexane, 2000 g of butadiene, and 2 mmol of tetramethylethylenediamine (TMEDA) were added to a 30 L pressure-resistant container that was sufficiently purged with nitrogen, and the temperature was raised to 60°C. Next, after adding 10.3 mL of butyllithium, the temperature was raised to 50° C. and stirred for 3 hours. Next, 11.5 mL of the above terminal modifier was added and stirred for 30 minutes. After adding 15 mL of methanol and 0.1 g of 2,6-tert-butyl-p-cresol to the reaction solution, the reaction solution was placed in a stainless steel container containing 18 L of methanol to collect aggregates. The obtained aggregate was dried under reduced pressure for 24 hours to obtain modified BR (BR1). As a result of the analysis, the cis content of the obtained modified BR was 36% by mass, the Mw was 430,000, and the vinyl content was 12% by mole.

Below, various chemicals used in the examples will be collectively explained.
NR:TSR20
SBR1: SBR1 produced in Production Example 1
BR1: Modified BR (BR1) produced in Production Example 2
BR2: BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass, Mw: 440,000, vinyl content: 1 mol%)
Silica: Ultrasil VN3 manufactured by Degussa (N ₂ SA: 175 m ² /g)
Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Carbon black: Diablack N220 (N ₂ SA: 114 m ² /g) manufactured by Mitsubishi Chemical Corporation
Plasticizer: Diana process oil AH-24 (aroma process oil) manufactured by Idemitsu Kosan Co., Ltd.
Anti-aging agent: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Stearic acid: stearic acid “Tsubaki” manufactured by NOF Corporation
Zinc oxide: 3 types of zinc oxide manufactured by Hakusui Tech Co., Ltd. Wax: Ozoace 0355 (paraffin wax) manufactured by Nippon Seiro Co., Ltd.
Sulfur: Powder sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noxeler NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Vulcanization accelerator 2: Noxela D (N,N'-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

<Examples and comparative examples>
According to the formulation shown in Table 1, materials other than sulfur and vulcanization accelerator were kneaded for 5 minutes at 150°C using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd., and the kneaded material was mixed. Obtained. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded for 5 minutes at 80° C. using a twin-screw open roll to obtain an unvulcanized rubber composition.
The obtained unvulcanized rubber composition was molded into the shape of a cap tread, bonded together with other tire members to form an unvulcanized tire, and press-vulcanized for 10 minutes at 170°C to obtain a test tire. (Size: 195/65R15, passenger car tire) was manufactured. The following evaluations were performed using the obtained test tires. The evaluation results are shown in Table 1.

(Low fuel efficiency)
Using a rolling resistance tester, the rolling resistance was measured and compared when the test tire was run on a rim (15 x 6 JJ), internal pressure (230 kPa), load (3.43 kN), and speed (80 km/h). It is expressed as an index when Example 2 is set as 100 (rolling resistance index). The larger the index value, the better the fuel efficiency performance, and if the index value is 90 or more, it can be said that sufficient fuel efficiency performance is ensured.

(Wet grip performance)
Each test tire was attached to all wheels of a vehicle (domestic FF2000cc), and the braking distance from an initial speed of 100 km/h on a wet asphalt road surface was determined and expressed as an index when Comparative Example 2 was set as 100 (wet skid figure of merit). The larger the index, the shorter the braking distance and the better the wet skid performance (wet grip performance).If the index value is greater than 100, it can be said that sufficient wet grip performance is ensured.

(Wear resistance performance)
Each test tire was installed on a domestically produced front-wheel drive vehicle, the groove depth of the tire cap tread was measured after a mileage of 8000km, and the mileage when the tire groove depth decreased by 1mm was calculated, and Comparative Example 2 was set as 100. (wear resistance performance index). The larger the index, the longer the distance traveled when the tire groove depth decreases by 1 mm, indicating that the tire has excellent wear resistance.

From the results in Table 1, it can be seen that a butadiene rubber (1) with a cis content of 40% by mass or less, a butadiene rubber (2) with a cis content of 95% by mass or more, a rubber component containing natural rubber, and a filler, In an example in which the content of butadiene rubber (1), butadiene rubber (2), and filler is a predetermined amount, it is possible to improve the wear resistance performance while ensuring the wet grip performance and low fuel consumption performance of the tire. It has become clear that wet grip performance, fuel efficiency, and wear resistance can be improved in a well-balanced manner.

Claims (3)

Contains rubber components and fillers,
The rubber component includes styrene-butadiene rubber, butadiene rubber (1), butadiene rubber (2), and natural rubber,
The styrene-butadiene rubber has a vinyl content of 10 to 50 mol%,
The butadiene rubber (1) has a cis content of 40% by mass or less,
The butadiene rubber (2) has a cis content of 95% by mass or more,
The content of the butadiene rubber (1) in 100% by mass of the rubber component is 5 to 20% by mass, the content of the butadiene rubber (2) is 10 to 25% by mass , and the content of the natural rubber is 5 to 30% by mass. mass% ,
A rubber composition for tires, wherein the content of the filler is 50 to 80 parts by mass based on 100 parts by mass of the rubber component. The rubber composition for tires according to claim 1 , wherein the butadiene rubber (1) is a modified butadiene rubber having a functional group that interacts with silica. A tire produced using the rubber composition according to claim 1 or 2 .