Rubber composition and tire

Abstract

To provide rubber compositions and tires having excellent overall performance in terms of dispersion of silica and fuel economy.SOLUTION: Rubber compositions contain a polymer (A) having a silanol group, a polymer (B) having a basic functional group, and silica.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a rubber composition and a tire. [Background technology]

[0002] Silica is widely used as a reinforcing filler for the purpose of improving the fuel economy of rubber compositions, and for example, Patent Document 1 discloses a rubber composition containing a specific modified polymer and silica. However, in recent years, the demand for improvement in fuel economy has become strict, and further improvement in performance is desired. On the other hand, since the time it takes for the tire temperature to reach an equilibrium state has been extended due to the improvement in fuel economy performance thus far, and the annual average temperature has become higher than before, there is a demand for an improvement in the temperature dependency of tire rolling resistance more than before. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-224835 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides a rubber composition that improves the temperature dependency of heat generation by increasing the dispersibility of silica and has excellent overall fuel economy at a constant temperature, and an object of the present invention is to provide a rubber composition and a tire that have improved rolling resistance over a wide range of temperatures. [Means for solving the problem]

[0005] The present invention relates to a rubber composition comprising a polymer (A) having a silanol group, a polymer (B) having a basic functional group, and silica.

[0006] It is preferred that polymer (A) has a silanol group other than at the terminal, and polymer (B) has a tertiary amino group.

[0007] The modification rate of the polymer (A) is preferably 5% or more. The modification rate of the polymer (B) is preferably 5% or more.

[0008] The rubber composition preferably contains 80 parts by mass or more of silica per 100 parts by mass of the rubber component.

[0009] The nitrogen adsorption specific surface area of ​​silica is 170m 2 It is preferable that the molecular weight is 1 / g or more.

[0010] The rubber composition preferably contains a mercapto-based silane coupling agent.

[0011] It is preferable that the polymers (A) and (B) have aromatic vinyl units based on an aromatic vinyl compound and conjugated diene units based on a conjugated diene compound, and further contain a styrene-based resin.

[0012] It is preferable that the rubber composition contains a plasticizer containing a resin, and the contents of the plasticizer and the resin satisfy the following formula. Resin content / plasticizer content ≧0.50

[0013] It is preferable that the rubber composition contains a plasticizer and silica, and the contents of the plasticizer and the silica satisfy the following formula. Plasticizer content / Silica content≧0.50

[0014] It is preferable that the rubber composition is produced by a manufacturing method including a first base kneading step of kneading a rubber component containing the polymers (A) and (B), a second base kneading step of kneading the first kneaded material obtained in the first base kneading step and silica, and a finish kneading step of kneading the second kneaded material obtained in the second base kneading step and a vulcanization-based material.

[0015] The present invention also relates to a tire using the rubber composition. Effect of the Invention

[0016] According to the present invention, the rubber composition contains a polymer (A) having a silanol group, a polymer (B) having a basic functional group, and silica, and therefore the dispersibility of the silica is increased, improving the temperature dependency of heat generation, while providing a rubber composition that is excellent overall in fuel economy at a constant temperature. As a result, a rubber composition and a tire with improved rolling resistance over a wide range of temperatures can be provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention is a rubber composition comprising a polymer (A) having a silanol group, a polymer (B) having a basic functional group, and silica.

[0018] The mechanism by which the above-mentioned effects are achieved is not clear, but is presumed to be as follows. In order to improve the temperature dependency and reduce heat generation, it is considered necessary to make the domains of the polymer bound by the silica in the rubber composition uniform and fine, and to sufficiently bond with the polymer. However, since the silica surface is hydrophilic, it is difficult to increase the dispersibility and to obtain a good bond with the polymer. Therefore, as a first step, it is considered necessary to hydrophobize the silica during mixing to increase the dispersibility in the rubber component. Since the hydrophobization reaction of the silica surface is easily carried out under basic conditions, it is considered that the silica incorporated in the polymer (B) is easily hydrophobized and is more easily incorporated into the polymer by providing a basic functional group in advance. Next, the polymer and silica are chemically bonded via a silane coupling agent, and it is considered that the presence of a silanol group in the polymer can promote the bond. By exerting the above-mentioned functions, the dispersibility of silica in the rubber composition is improved, which makes the domains bound by silica uniform, improves temperature dependency, and improves fuel economy at constant temperatures such as room temperature. As a result, it is believed that these overall performance characteristics are improved and rolling resistance (fuel economy) can be achieved over a wide range of temperatures.

[0019] (Rubber component) The rubber composition contains a silanol group-containing polymer (A) as a rubber component. Examples of the polymer constituting the polymer (A) having a silanol group include a polymer having a conjugated diene unit based on a conjugated diene compound, a polymer having an aromatic vinyl unit based on an aromatic vinyl compound and a conjugated diene unit based on a conjugated diene compound, etc. Among them, a polymer having an aromatic vinyl unit based on an aromatic vinyl compound and a conjugated diene unit based on a conjugated diene compound is preferable.

[0020] Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 1,3-hexadiene, myrcene, and farnesene. The conjugated diene compound is preferably 1,3-butadiene or isoprene.

[0021] Examples of the aromatic vinyl compound include styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene. The aromatic vinyl compound is preferably styrene.

[0022] The polymer having a silanol group (A) may be a rubber used in the tire field, such as isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), styrene-isoprene-butadiene copolymer rubber (SIBR), or other diene rubber.

[0023] Among these, from the viewpoints of improving the temperature dependency of heat generation (dispersibility of silica), improving the overall performance of fuel economy at a constant temperature, and improving rolling resistance over a wide range of temperatures, isoprene-based rubber, BR, and SBR are preferred, and SBR is more preferred.

[0024] Examples of the polymer (A) include terminally modified polymers (terminally modified polymers having a silanol group at the terminal) in which at least one terminal of the polymer has been modified with a compound (modifying agent) having a silanol group, main-chain modified polymers having a silanol group in the main chain (a site other than the terminal of the polymer chain), and main-chain terminal-modified polymers having silanol groups in the main chain and at the terminals (for example, main-chain terminal polymers having a silanol group in the main chain and at least one terminal modified with a compound (modifying agent) having a silanol group).

[0025] Among them, modified polymers having silanol groups at least in places other than the terminals (main chain, side chain, etc.) are preferred, and modified polymers having silanol groups at least in the main chain (such as the main chain modified polymer and the main chain end modified polymer having silanol groups in the main chain and at the terminals) are more preferred. In this case, since silanol groups are provided in the main chain of polymer (A), the entire polymer (A) is in a state in which it is easy to bond with silica, and while obtaining good silica dispersibility, the movement of the main chain of the polymer is restricted by silica, so that the dispersibility of silica is increased, the temperature dependency of heat generation is improved, and fuel efficiency at a constant temperature is improved overall, and rolling resistance is improved over a wide range of temperatures.

[0026] The first embodiment of the polymer (A) having a silanol group is that the silanol group of the polymer (A) is a pendant group. In this case, the silicon atom of the silanol group is usually not inserted between the carbon-carbon bonds of the main chain of the polymer (A). The polymer (A) having a silanol group as a pendant group can be prepared, for example, by hydrosilylation of the polymer chain with a silane compound having an alkoxysilane functional group, followed by hydrolysis of the alkoxysilane functional group to form a silanol functional group (silanol group).

[0027] The second embodiment of the polymer (A) having a silanol group is one in which the silanol group of the polymer (A) is located on the polymer chain, not on the pendant group.In this case, the silicon atom of the silanol group is usually inserted between the carbon-carbon bonds of the polymer chain.The polymer (A) having such a silanol group can be prepared, for example, by a coupling reaction with a coupling agent (modifier) ​​having an alkoxysilane functional group and an amine functional group, followed by hydrolysis of the alkoxysilane functional group to a silanol functional group (silanol group).

[0028] As the amine functional group, for example, a tertiary amine is preferred. As the tertiary amine functional group, preferably C1-C 10 Examples thereof include a tertiary amine group substituted with an alkyl group, more preferably a C1-C4 alkyl group, and even more preferably a methyl group or an ethyl group.

[0029] Specifically, the compound (modifier) ​​represented by the following formula can be suitably used as the modifier (coupling agent). [ka] (In the formula, R 1 , R 2 and R 3 R may be the same or different and represents an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or a derivative thereof. 4 and R 5 R may be the same or different and represents a hydrogen atom or an alkyl group. 4 and R 5 may be bonded to form a ring structure together with the nitrogen atom, and n represents an integer.

[0030] R 1 , R 2 and R 3 is preferably an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms), and R 1 , R 2 and R 3At least one of R is preferably an alkoxy group. 4 and R 5 is preferably an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and further preferably 3. In addition, R 4 and R 5 When the nitrogen atom and the nitrogen atom are bonded to each other to form a ring structure, the ring is preferably a 4- to 8-membered ring. The alkoxy group also includes a cycloalkoxy group (such as a cyclohexyloxy group) and an aryloxy group (such as a phenoxy group and a benzyloxy group).

[0031] Specific examples of the modifying agent include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc. Among these, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropyltriethoxysilane, and 3-diethylaminopropyltrimethoxysilane are preferred.

[0032] In addition, as the modifying agent, N,N-bis(trimethylsilyl)aminopropyl methyl dimethoxysilane, 1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane, N,N-bis(trimethylsilyl)aminopropyl trimethoxysilane, N,N-bis(trimethylsilyl)aminopropyl triethoxysilane, N,N-bis(trimethylsilyl)aminopropyl methyl diethoxysilane, N,N-bis(trimethylsilyl)aminoethyl trimethoxysilane, N,N-bis(trimethylsilyl)aminoethyl triethoxysilane, N,N-bis(trimethylsilyl)aminoethyl methyl dimethoxysilane, and N,N-bis(trimethylsilyl)aminoethyl methyl diethoxysilane can also be used. These modifying agents may be used alone or in combination of two or more.

[0033] The method of hydrolyzing the alkoxysilane functional groups of the polymer chain to convert them to silanol functional groups can be carried out by a step of stripping the polymer-containing solution, for example, according to the method described in JP 2014-122357 A (incorporated herein by reference).

[0034] The polymer chain of the polymer (A) having a silanol group is preferably mainly linear. When the polymer (A) contains star chains or branched chains, the proportion of these in the polymer (A) is preferably small, and for example, the amount of star chains and branched chains present in the polymer (A) is preferably 0% to less than 50% by mass in the total mass of the polymer (A) (100% by mass). The polymer (A) is usually a mixture of polymers having different chemical properties of amine functional groups, microstructures or macrostructures.

[0035] In the rubber composition, the content of the polymer (A) in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 20% by mass or more, even more preferably 35% by mass or more, and particularly preferably 45% by mass or more. The upper limit is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. By keeping the content within the above range, the dispersibility of silica is increased, improving the temperature dependency of heat generation, and fuel economy at a constant temperature is improved overall, and rolling resistance over a wide range of temperatures tends to be improved.

[0036] The modification rate of the polymer (A) is preferably 5% or more, more preferably 6% or more, and even more preferably 7% or more, from the viewpoint of the overall performance of silica dispersibility and fuel economy. The upper limit of the modification rate is preferably 12% or less, more preferably 10% or less, and even more preferably 9% or less. It is presumed that by making the modification rate 5% or more, it is possible to efficiently bond with silica and reduce heat generation. The modification rate is a value measured by the method described in the Examples section below.

[0037] The rubber composition includes a polymer (B) having a basic functional group as a rubber component. Examples of the basic functional group in the polymer (B) having a basic functional group include an amino group, an imino group (=NH), and an ammonium base. The amino group may be any of a primary amino group (-NH2), a secondary amino group (-NHR), and a tertiary amino group (-NRR'). The R and R' are an alkyl group, a phenyl group, an aralkyl group, and the like, and preferably have 1 to 8 carbon atoms. The R and R' of the tertiary amino group (-NRR') may constitute a heterocyclic group having a basic nitrogen atom. Examples of the heterocyclic group having a basic nitrogen atom include nitrogen-containing heterocyclic groups such as a pyridine group, a pyrimidine group, a pyrazine group, an imidazole group, an imidazole group containing a thiol, a triazole group, and a thiazole group. In the case of a heterocyclic group, the presence of a double bond makes it easy to disperse in the rubber. Examples of the ammonium base include tertiary ammonium base and quaternary ammonium base. Among the basic functional groups, amino groups (amine groups) are preferred, and tertiary amino groups such as heterocyclic groups having a basic nitrogen atom are more preferred. In particular, in the case of tertiary amino groups, it is presumed that the tertiary amino groups in polymer B make the silica incorporated in polymer B more hydrophobic, and more easily incorporated into the polymer.

[0038] Examples of the polymer constituting the polymer (B) having a basic functional group include the same polymers as those constituting the polymer (A). Among them, preferred are polymers having aromatic vinyl units based on aromatic vinyl compounds and conjugated diene units based on conjugated diene compounds, isoprene-based rubber, BR, and SBR, and particularly preferred is SBR.

[0039] In the rubber composition, the content of the polymer (B) in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 20% by mass or more, even more preferably 35% by mass or more, and particularly preferably 45% by mass or more. The upper limit is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. By keeping the content within the above range, the dispersibility of silica is increased, improving the temperature dependency of heat generation, and fuel economy at a constant temperature is improved overall, and rolling resistance over a wide range of temperatures tends to be improved.

[0040] The modification rate of the polymer (B) is preferably 5% or more, more preferably 6% or more, and even more preferably 7% or more, from the viewpoint of the overall performance of silica dispersibility and fuel economy. The upper limit of the modification rate is preferably 12% or less, more preferably 10% or less, and even more preferably 9% or less. It is presumed that by making the modification rate 5% or more, it is possible to efficiently promote the hydrophobization reaction of silica and increase the dispersibility of silica. The modification rate is a value measured by the method described in the Examples section below.

[0041] In the rubber composition, from the viewpoint of overall performance such as silica dispersibility and fuel economy, the total content of the polymer (A) and the polymer (B) in 100% by mass of the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and may be 100% by mass.

[0042] The weight average molecular weight (Mw) of the polymers (A) and (B) is preferably 100,000 or more, more preferably 200,000 or more, and even more preferably 300,000 or more. If it is above the lower limit, the high molecular weight ensures the rigidity of the rubber, and the balance between fuel efficiency and steering stability tends to be improved. The upper limit of the Mw is not particularly limited, but is preferably 1,000,000 or less, more preferably 800,000 or less, and even more preferably 700,000 or less.

[0043] The styrene content of the polymers (A) and (B) is preferably 5% by mass or more, more preferably 15% by mass or more, and even more preferably 25% by mass or more. The styrene content is preferably 45% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less. By keeping it within the above range, the dispersibility of silica is increased, improving the temperature dependency of heat generation, and the fuel economy at a constant temperature is improved overall, and the rolling resistance over a wide range of temperatures tends to be improved.

[0044] The vinyl bond content of the polymers (A) and (B) is preferably 20% by mass or more, more preferably 35% by mass or more, and even more preferably 45% by mass or more. The vinyl bond content is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. By keeping it within the above range, the dispersibility of silica is increased, improving the temperature dependency of heat generation, and the fuel economy at a constant temperature is improved overall, and the rolling resistance over a wide range of temperatures tends to be improved.

[0045] In this specification, the weight average molecular weight (Mw) can be determined by converting the measured value into a standard polystyrene equivalent value using a gel permeation chromatograph (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation). The vinyl bond amount (amount of 1,2-bonded butadiene units) can be measured by infrared absorption spectroscopy, and the styrene content can be determined by the following method: 1 It can be measured by H-NMR measurement.

[0046] In the rubber composition, the blending ratio of the polymers (A) and (B) (content (parts by mass) of the polymer (A) / content (parts by mass) of the polymer (B)) is preferably 20 / 80 or more, more preferably 30 / 70 or more, and even more preferably 40 / 60 or more. The blending ratio is preferably 80 / 20 or less, more preferably 70 / 30 or less, and even more preferably 60 / 40 or less. By keeping the blending ratio within the above range, the dispersibility of silica is increased, improving the temperature dependency of heat generation, and fuel economy at a constant temperature is improved overall, and rolling resistance over a wide range of temperatures tends to be improved.

[0047] The rubber composition may contain a rubber component other than the polymers (A) and (B). Examples of the other rubber component include the polymers constituting the polymers (A) and (B).

[0048] Examples of silica include dry process silica (anhydrous silica), wet process silica (hydrated silica), etc. Among these, wet process silica is preferred because it has a large number of silanol groups.

[0049] The content of silica is preferably 5 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 70 parts by mass or more, and particularly preferably 80 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 150 parts by mass or less, more preferably 130 parts by mass or less, and even more preferably 120 parts by mass or less. By setting it within the above range, the dispersibility of silica is increased, improving the temperature dependency of heat generation, and fuel efficiency at a constant temperature is generally improved, and rolling resistance tends to be improved over a wide range of temperatures. In particular, by setting it to 80 parts by mass or more, the probability of silica meeting the modifying group is increased, so that the above effect is presumably obtained more significantly.

[0050] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 50 m 2 / g or more, more preferably 100m 2 / g or more, more preferably 150m 2 / g or more, particularly preferably 170m 2The N2SA of the silica is preferably 300m 2 / g or less, more preferably 250m 2 / g or less, more preferably 200m 2 By keeping the ratio within the above range, the dispersibility of silica is increased, improving the temperature dependency of heat generation, while fuel economy at a constant temperature is improved overall, and rolling resistance over a wide range of temperatures tends to be improved. 2 / g or more, the specific surface area of ​​the silica becomes large, so that the number of reaction sites with the polymer increases, making it possible to more effectively bind the polymer, and thus reducing heat generation. The N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0051] As the silica, for example, products manufactured by Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0052] From the viewpoints of improving the temperature dependency of heat generation (dispersibility of silica) and the overall performance of fuel economy at a constant temperature, and improving rolling resistance over a wide range of temperatures, it is preferable that the total content (parts by mass) of the polymer (A) and the polymer (B) and the content (parts by mass) of silica in the rubber composition satisfy the following formula: The content of silica / the total content of the polymer (A) and the polymer (B) is ≧0.50 The silica content / total content of the polymer (A) and the polymer (B) is more preferably ≧0.60, even more preferably ≧0.70, and particularly preferably ≧0.75. The upper limit of the silica content / total content of the polymer (A) and the polymer (B) is preferably ≦1.30, more preferably ≦1.10, and even more preferably ≦1.00.

[0053] The rubber composition preferably contains a silane coupling agent together with silica. The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, 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-trimethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N Examples of such silanes include sulfide-based silanes such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, vinyl-based silanes such as vinyltriethoxysilane, vinyltrimethoxysilane, amino-based silanes such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, glycidoxy-based silanes such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, nitro-based silanes such as 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, and chloro-based silanes such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane. As commercially available products, for example, products from Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used. These may be used alone or in combination of two or more. Among them, sulfide-based and mercapto-based silane coupling agents are preferred, and mercapto-based silane coupling agents are particularly preferred.It is presumed that the use of a mercapto-based silane coupling agent makes it possible to increase the reactivity between the silica and the coupling agent, which in turn promotes the reaction between the hydrophobized silica and the polymer, thereby reducing heat generation.

[0054] Particularly suitable mercapto-based silane coupling agents include silane coupling agents represented by the following formula (S1) and silane coupling agents containing a bond unit A represented by the following formula (I) and a bond unit B represented by the following formula (II). Among these, silane coupling agents containing a bond unit A represented by the following formula (I) and a bond unit B represented by the following formula (II) are preferred. [ka] (In the formula, R 1001 -Cl, -Br, -OR 1006 , -O(O=)CR 1006 , -ON=CR 1006 R 1007 , -NR 1006 R 1007 and-(OSiR 1006 R 1007 ) h (OSiR 1006 R 1007 R 1008 ) a monovalent group (R 1006 , R 1007 and R 1008 may be the same or different, each is a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and h has an average value of 1 to 4; 1002 is R 1001 , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R 1003 is -[O(R 1009 O) j ]-group(R 1009 is an alkylene group having 1 to 18 carbon atoms, and j is an integer of 1 to 4. 1004 is a divalent hydrocarbon group having 1 to 18 carbon atoms, R 1005 represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, and x, y, and z are numbers that satisfy the relationship: x+y+2z=3, 0≦x≦3, 0≦y≦2, 0≦z≦1. [ka] [ka] (In the formula, x is an integer of 0 or more, and y is an integer of 1 or more. R 1 R represents 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 an alkyl group in which the terminal hydrogen atom has been substituted with a hydroxyl group or a carboxyl group. 2 R represents a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, or a branched or unbranched alkynylene group having 2 to 30 carbon atoms. 1 and R 2 may form a ring structure.)

[0055] In formula (S1), R 1005 , R 1006 , R 1007 and R 1008 are each preferably independently selected from the group consisting of a linear, cyclic or branched alkyl group, an alkenyl group, an aryl group and an aralkyl group having 1 to 18 carbon atoms. 1002 When R is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is preferably a group selected from the group consisting of linear, cyclic or branched alkyl groups, alkenyl groups, aryl groups and aralkyl groups. 1009 R is preferably a linear, cyclic or branched alkylene group, and particularly preferably a linear one. 1004 Examples of R include an alkylene group having 1 to 18 carbon atoms, an alkenylene group having 2 to 18 carbon atoms, a cycloalkylene group having 5 to 18 carbon atoms, a cycloalkylalkylene group having 6 to 18 carbon atoms, an arylene group having 6 to 18 carbon atoms, and an aralkylene group having 7 to 18 carbon atoms. The alkylene group and the alkenylene group may be either linear or branched, and the cycloalkylene group, the cycloalkylalkylene group, the arylene group, and the aralkylene group may have a functional group such as a lower alkyl group on the ring. This R 1004As the alkylene group, an alkylene group having 1 to 6 carbon atoms is preferable, and a linear alkylene group such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, or a hexamethylene group is particularly preferable.

[0056] R in formula (S1) 1002 , R 1005 , R 1006 , R 1007 and R 1008 Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a cyclopentyl group, a cyclohexyl group, a vinyl group, a propenyl group, an allyl group, a hexenyl group, an octenyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a benzyl group, a phenethyl group, and a naphthylmethyl group. R in formula (S1) 1009 Examples of the linear alkylene group include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, and a hexylene group, and examples of the branched alkylene group include an isopropylene group, an isobutylene group, and a 2-methylpropylene group.

[0057] Specific examples of the silane coupling agent represented by formula (S1) include 3-hexanoylthiopropyl triethoxysilane, 3-octanoylthiopropyl triethoxysilane, 3-decanoylthiopropyl triethoxysilane, 3-lauroylthiopropyl triethoxysilane, 2-hexanoylthioethyl triethoxysilane, 2-octanoylthioethyl triethoxysilane, 2-decanoylthioethyl triethoxysilane, 2-lauroylthioethyl triethoxysilane, 3-hexanoylthiopropyl trimethoxysilane, 3-octanoylthiopropyl trimethoxysilane, 3-decanoylthiopropyl trimethoxysilane, 3-lauroylthiopropyl trimethoxysilane, 2-hexanoylthioethyl trimethoxysilane, 2-octanoylthioethyl trimethoxysilane, 2-decanoylthioethyl trimethoxysilane, and 2-lauroylthioethyl trimethoxysilane. These may be used alone or in combination of two or more kinds. Among them, 3-octanoylthiopropyltriethoxysilane is particularly preferable.

[0058] In the silane coupling agent containing the bond unit A represented by formula (I) and the bond unit B represented by formula (II), the content of the bond unit A is preferably 30 mol% or more, more preferably 50 mol% or more, and preferably 99 mol% or less, more preferably 90 mol% or less. The content of the bond unit B is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and preferably 70 mol% or less, more preferably 65 mol% or less, even more preferably 55 mol% or less. The total content of the bond 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 bond units A and B includes the case where the bond units A and B are located at the terminals of the silane coupling agent. When the bond units A and B are located at the terminals of the silane coupling agent, the form is not particularly limited, and it is sufficient that they form units corresponding to the formulas (I) and (II) representing the bond units A and B.

[0059] R in formula (I) and (II)1 With respect to the above, examples of halogen include chlorine, bromine, and fluorine. Examples of branched or unbranched alkyl groups having 1 to 30 carbon atoms include methyl and ethyl groups. Examples of branched or unbranched alkenyl groups having 2 to 30 carbon atoms include vinyl and 1-propenyl groups. Examples of branched or unbranched alkynyl groups having 2 to 30 carbon atoms include ethynyl and propynyl groups.

[0060] R in formula (I) and (II) 2 Regarding the above, examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms include an ethylene group, a propylene group, etc. Examples of the branched or unbranched alkenylene group having 2 to 30 carbon atoms include a vinylene group, a 1-propenylene group, etc. Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms include an ethynylene group, a propynylene group, etc.

[0061] In a silane coupling agent containing a bonding unit A represented by formula (I) and a bonding unit B represented by formula (II), the total number of repetitions (x+y) of the bonding unit A and the bonding unit B is preferably in the range of 3 to 300.

[0062] When a silane coupling agent is contained, the content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, per 100 parts by mass of silica.

[0063] Examples of carbon black that can be used in the rubber composition include, but are not limited to, GPF, FEF, HAF, ISAF, SAF, etc. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Shin-Nichika Carbon Co., Ltd., Columbia Carbon Co., Ltd., etc. By blending carbon black, reinforcing properties are obtained and abrasion resistance and the like are significantly improved.

[0064] In the rubber composition, the content of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, based on 100 parts by mass of the rubber component. By making it equal to or more than the lower limit, the effect of blending carbon black tends to be obtained. In addition, the content of carbon black is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less. By making it equal to or less than the upper limit, good dispersibility tends to be obtained.

[0065] The nitrogen adsorption specific surface area (N2SA) of the carbon black is preferably 80 m 2 / g or more, more preferably 100m 2 / g or more, more preferably 105m 2 When the N2SA is equal to or higher than the lower limit, good reinforcing properties tend to be obtained. The upper limit of the N2SA of the carbon black is not particularly limited, but is preferably 180 m 2 / g or less, more preferably 150m 2 / g or less, more preferably 130m 2 / g or less. The nitrogen adsorption specific surface area of ​​carbon black is determined by Method A of JIS K6217.

[0066] The rubber composition may contain a filler other than silica and carbon black, such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, mica, or other fillers known in the rubber field.

[0067] The rubber composition preferably contains a plasticizer. The plasticizer means a material that has the effect of plasticizing rubber, and examples thereof include liquid plasticizers (plasticizers that are in a liquid state at 25°C) and resins. Here, the resin refers to a resin that is in a solid state at room temperature (25°C). In particular, a rubber composition in which a plasticizer is blended with a rubber component containing SBR is preferred, and a rubber composition in which a resin is blended with a rubber component containing SBR is more preferred.

[0068] In the rubber composition, the content of the plasticizer (total amount of plasticizers such as liquid plasticizers and resins) is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 45 parts by mass or more, and particularly preferably 55 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is not particularly limited, but is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 80 parts by mass or less. By keeping it within the above range, the dispersibility of silica is increased, improving the temperature dependency of heat generation, and fuel efficiency at a constant temperature is improved overall, and rolling resistance over a wide range of temperatures tends to be improved.

[0069] In the rubber composition, the content of the liquid plasticizer is preferably 3 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is not particularly limited, but is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less. By keeping the content within the above range, the dispersibility of silica is increased, improving the temperature dependency of heat generation, and the fuel economy at a constant temperature is improved overall, and the rolling resistance over a wide range of temperatures tends to be improved.

[0070] The liquid plasticizer is not particularly limited, and examples thereof include oil, liquid resin, liquid diene polymer, etc. These may be used alone or in combination of two or more kinds.

[0071] Examples of the oil include process oil, vegetable oil, or a mixture thereof. Examples of the process oil include paraffin-based process oil, aromatic process oil, and naphthenic process oil. Examples of the vegetable oil 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 oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Examples of commercially available products include those from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi Co., Ltd., H&R Corporation, Toyokuni Seiyu Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Co., Ltd.

[0072] Examples of liquid resins include terpene resins (including terpene phenol resins and aromatic modified terpene resins) that are liquid at 25°C, rosin resins, styrene resins, C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene (DCPD) resins, coumarone-indene resins (including coumarone and indene simple resins), phenol resins, olefin resins, polyurethane resins, and acrylic resins.

[0073] Examples of liquid diene polymers include liquid styrene butadiene copolymers (liquid SBR), liquid butadiene polymers (liquid BR), liquid isoprene polymers (liquid IR), liquid styrene isoprene copolymers (liquid SIR), liquid styrene butadiene styrene block copolymers (liquid SBS block polymers), liquid styrene isoprene styrene block copolymers (liquid SIS block polymers), liquid farnesene polymers, liquid farnesene butadiene copolymers, etc., which may be modified at the ends or main chains with polar groups.

[0074] In the rubber composition, the resin content is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and particularly preferably 23 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is not particularly limited, but is preferably 70 parts by mass or less, more preferably 55 parts by mass or less, and even more preferably 50 parts by mass or less. By keeping the content within the above range, the dispersibility of silica is increased, improving the temperature dependency of heat generation, and fuel economy at a constant temperature is improved overall, and rolling resistance over a wide range of temperatures tends to be improved.

[0075] The softening point of the resin is preferably 60° C. or higher, more preferably 70° C. or higher, and even more preferably 80° C. or higher, from the viewpoints of improving the temperature dependency of heat generation (dispersibility of silica), improving the overall performance of fuel economy at a constant temperature, and improving rolling resistance over a wide range of temperatures. In addition, the upper limit of the softening point is not particularly limited, but is preferably 180° C. or lower, more preferably 160° C. or lower, and even more preferably 140° C. or lower. The softening point of the resin 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 tester.

[0076] The resin is not particularly limited, but examples thereof include coumarone resins, styrene resins, terpene resins, dicyclopentadiene resins (DCPD resins), C5 petroleum resins, C9 petroleum resins, C5C9 petroleum resins, pt-butylphenol acetylene resins, acrylic resins, etc. These may be used alone or in combination of two or more. The resin may also be hydrogenated.

[0077] Among them, terpene resin, styrene resin, DCPD resin are preferred, and styrene resin is more preferred.In particular, when the polymer (A) and (B) are used with the aromatic vinyl unit based on aromatic vinyl compound and the conjugated diene unit based on conjugated diene compound, and styrene resin is blended, it is presumed that the above-mentioned effect of having the common unit between polymer (A) and (B), the compatibility of polymer (A) and (B) is improved by styrene resin, and the silica incorporated in polymer (B) is more easily inserted into the polymer (A) phase, so that the overall performance of silica dispersibility and heat generation is significantly improved.

[0078] The styrene resin is a polymer using a styrene monomer as a constituent monomer, and examples thereof include polymers polymerized with a styrene monomer as the main component (50% by mass or more). Specifically, examples thereof include homopolymers obtained by polymerizing each of styrene monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) alone, copolymers obtained by copolymerizing two or more kinds of styrene monomers, and copolymers of a styrene monomer and another monomer that can be copolymerized therewith. These may be used alone or in combination of two or more kinds.

[0079] Examples of the other monomer include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylic acid and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, dienes such as chloroprene and butadiene-isoprene, olefins such as 1-butene and 1-pentene, α,β-unsaturated carboxylic acids or acid anhydrides thereof such as maleic anhydride, and the like. Of the styrene-based resins, α-methylstyrene-based resins (such as α-methylstyrene homopolymers and copolymers of α-methylstyrene and styrene) are preferable.

[0080] The terpene resin is not particularly limited as long as it is a resin having a unit derived from a terpene compound, and examples thereof include polyterpene (a resin obtained by polymerizing a terpene compound), terpene aromatic resin (a resin obtained by copolymerizing a terpene compound and an aromatic compound), and aromatic modified terpene resin (a resin obtained by modifying a terpene resin with an aromatic compound). These may be used alone or in combination of two or more kinds. Among them, polyterpene is preferred.

[0081] The above terpene compound is (C5H8) n The hydrocarbons and their oxygen-containing derivatives represented by the composition 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ), and examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol. The terpene compounds also include resin acids (rosin acids) such as abietic acid, neoabietic acid, palustric acid, levopimaric acid, pimaric acid, and isopimaric acid. In other words, the terpene resins include rosin resins whose main component is rosin acid obtained by processing pine resin. Examples of rosin resins include naturally occurring rosin resins (polymerized rosins) such as gum rosin, wood rosin, and tall oil rosin, as well as modified rosin resins such as maleic acid modified rosin resin and rosin modified phenolic resin, rosin esters such as rosin glycerin ester, and disproportionated rosin resins obtained by disproportionating rosin resin.

[0082] The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring, and examples thereof include phenolic compounds such as phenol, alkylphenol, alkoxyphenol, and unsaturated hydrocarbon group-containing phenol; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and unsaturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene; etc. Among these, styrene is preferred.

[0083] Examples of the resins that can be used include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0084] From the viewpoints of improving the temperature dependency of heat generation (dispersibility of silica), improving the overall performance of fuel economy at a constant temperature, and improving rolling resistance over a wide range of temperatures, it is preferable that the plasticizer content (parts by mass) (total amount of plasticizers such as liquid plasticizer, resin, etc.) and the resin content (parts by mass) of the rubber composition satisfy the following formula: Resin content / plasticizer content ≧0.50 The resin content / plasticizer content is preferably ≧0.55, more preferably ≧0.57, and even more preferably ≧0.60. The upper limit of the resin content / plasticizer content is more preferably ≦0.90, more preferably ≦0.75, and particularly preferably ≦0.70.

[0085] From the viewpoints of improving the temperature dependency of heat generation (dispersibility of silica), improving the overall performance of fuel economy at a constant temperature, and improving rolling resistance over a wide range of temperatures, it is preferable that the plasticizer content (parts by mass) (total amount of plasticizers such as liquid plasticizer, resin, etc.) and the silica content (parts by mass) of the rubber composition satisfy the following formula: Plasticizer content / Silica content≧0.50 The plasticizer content / silica content is preferably ≧0.70, more preferably ≧0.80, and particularly preferably ≧0.85. The upper limit of the plasticizer content / silica content is preferably ≦1.10, more preferably ≦1.00, and even more preferably ≦0.95.

[0086] From the viewpoints of improving the temperature dependency of heat generation (dispersibility of silica) and the overall performance of fuel economy at a constant temperature, and improving rolling resistance over a wide range of temperatures, it is preferable that the resin content (parts by mass) and the silica content (parts by mass) of the rubber composition satisfy the following formula: Resin content / silica content ≧ 0.30 The resin content / silica content is preferably ≧0.40, more preferably ≧0.45, and particularly preferably ≧0.50. The upper limit of the resin content / silica content is preferably ≦1.00, more preferably ≦0.80, and particularly preferably ≦0.75.

[0087] The rubber composition may contain a wax. The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as vegetable wax and animal wax; and synthetic waxes such as polymers of ethylene, propylene, etc. These may be used alone or in combination of two or more. Among them, petroleum waxes are preferred, and paraffin wax is more preferred.

[0088] As the wax, for example, products available from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used.

[0089] When the wax is contained, the amount thereof is preferably 0.3 part by mass or more, more preferably 0.5 part by mass or more, and preferably 20 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component.

[0090] The rubber composition may contain an antioxidant. Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants 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, and N,N'-di-2-naphthyl-p-phenylenediamine. Examples of the antioxidant include p-phenylenediamine antioxidants such as quinolinone; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis, tris, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. These antioxidants may be used alone or in combination of two or more. Among them, p-phenylenediamine antioxidants and quinoline antioxidants are preferred.

[0091] As the antioxidant, for example, products available from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, etc. can be used.

[0092] When an antioxidant is contained, the content thereof is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component.

[0093] The rubber composition may contain stearic acid. As the stearic acid, any conventionally known product can be used, for example, products available from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., and the like.

[0094] When stearic acid is contained, the amount thereof is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component.

[0095] The rubber composition may contain zinc oxide. As the zinc oxide, any known zinc oxide can be used, for example, products available from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., and the like.

[0096] When zinc oxide is contained, the content thereof is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component.

[0097] The rubber composition may contain sulfur. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. These may be used alone or in combination of two or more kinds.

[0098] As sulfur, for example, products from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanritsu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0099] In the case where sulfur is contained, the amount thereof is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and further preferably 3 parts by mass or less, based on 100 parts by mass of the rubber component.

[0100] The rubber composition may contain 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-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. These may be used alone or in combination of two or more. Of these, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferred.

[0101] When a vulcanization accelerator is contained, the content thereof is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 7 parts by mass or less, based on 100 parts by mass of the rubber component.

[0102] In addition to the above components, the rubber composition may further contain other compounding agents (such as organic crosslinking agents) that are generally used in the tire industry. The content of these compounding agents is preferably 0.1 to 200 parts by mass per 100 parts by mass of the rubber component.

[0103] The rubber composition can be produced, for example, by kneading the above-mentioned components using a rubber kneading device such as an open roll or a Banbury mixer, and then press-molding the resulting kneaded mixture.

[0104] Regarding the kneading conditions for kneading each component, the kneading temperature is usually 100 to 180° C., preferably 120 to 170° C., and the kneading time is usually 1 to 30 minutes, preferably 2 to 10 minutes. Regarding the conditions for press-molding the kneaded product obtained by kneading, the temperature is usually 140 to 190° C., preferably 150 to 185° C., and the kneading time is usually 1 to 60 minutes, preferably 5 to 30 minutes.

[0105] The rubber composition is preferably prepared by a manufacturing method including a first base kneading step of kneading a rubber component containing the polymers (A) and (B), a second base kneading step of kneading a first kneaded material obtained in the first base kneading step with silica, and a finish kneading step of kneading a second kneaded material obtained in the second base kneading step with a vulcanization-based material.

[0106] The kneading method in the first base kneading step is not particularly limited, and for example, a known kneading machine such as a Banbury mixer, a kneader, etc. can be used. The kneading time in the first base kneading step is preferably 1 to 10 minutes, and the kneading temperature is preferably 130 to 160°C.

[0107] In the first base kneading step, the rubber component can be kneaded in whole or in part, but it is preferable to knead at least the polymers (A) and (B) in whole.

[0108] In the first base kneading step, ingredients other than the above ingredients may be appropriately kneaded.

[0109] The kneading method for the second base kneading step is not particularly limited, and for example, the same method as that for the first base kneading step can be used. The same kneading conditions (kneading time, kneading temperature) can also be used.

[0110] In the second base kneading step, all or a portion of the silica can be kneaded, but it is preferable to knead the entire amount.

[0111] In the second base kneading step, components other than silica may be kneaded as appropriate.

[0112] In the final mixing step, the second mixture obtained in the second base mixing step is mixed with the vulcanization material. The mixing method is not particularly limited, and for example, a known mixer such as an open roll can be used. The mixing time is preferably 0.5 to 15 minutes, and the mixing temperature is preferably 40 to 80°C.

[0113] In the final kneading step, the second kneaded material, sulfur, and a vulcanization accelerator are usually kneaded. In the first and second base kneading steps, if some of the materials that are usually kneaded in the base kneading are not kneaded, those materials may also be kneaded appropriately.

[0114] The rubber composition can be used (as a rubber composition for tires) for tire components such as treads (cap treads), sidewalls, base treads, under treads, clinches, bead apex, breaker cushion rubber, carcass cord covering rubber, insulation, chafers, inner liners, and side reinforcing layers of run-flat tires. Among them, the rubber composition can be suitably applied to treads.

[0115] The tire of the present invention is produced by a conventional method using the above rubber composition. That is, the rubber composition is extruded in an unvulcanized state to match the shape of tire components such as a tread, and molded together with other tire components in a tire building machine by a normal method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire.

[0116] The tire may be composed of at least a part (for example, a tread) of the rubber composition, or may be composed of the rubber composition in its entirety. The tire is preferably a pneumatic tire.

[0117] The pneumatic tire can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a heavy load tire such as a truck or a bus tire, a light truck tire, a two-wheeled vehicle tire, a racing tire (high performance tire), etc. It can also be used as an all-season tire, a summer tire, a winter tire (a studless tire, a tire for low-temperature road surface, etc.), etc. Among them, a passenger car tire is preferable. EXAMPLES

[0118] The present invention will be specifically described based on examples, but the present invention is not limited to these examples. Using the various chemicals shown below, rubber compositions with different formulations according to each table were prepared, and the rubber compositions were used in the tread of a tire with a tire size of 195 / 65R15. The silica dispersibility and rolling resistance (fuel economy) of the rubber compositions (vulcanized) at a constant tire temperature were calculated. The results are shown in the evaluation column of each table. The reference comparative examples in Tables 1 to 4 are Comparative Examples 1-1, 2-1, 3-1, and 4-1, respectively.

[0119] The various chemicals used in the examples and comparative examples will be described below. Unmodified SBR: SBR1502 manufactured by Sumitomo Chemical Co., Ltd. Modified polymer having silanol groups (A1): Production Example 1 below (terminally modified SBR, modification rate 8%, Mw 450,000, styrene content 27% by mass, vinyl bond amount 57% by mass) Modified polymer having silanol groups (A2): Production Example 1 below (terminally modified SBR, modification rate 9%, Mw 500,000, styrene content 24% by mass, vinyl bond amount 55% by mass) Modified polymer having silanol groups (A3): Production Example 2 below (main chain end-modified SBR, modification rate 7.5%, Mw 150,000, styrene content 26% by mass, vinyl bond amount 58% by mass) Modified polymer having silanol groups (A4): Production Example 2 below (main chain end-modified SBR, modification ratio 8.5%, Mw 200,000, styrene content 22% by mass, vinyl bond amount 48% by mass) Pyridine-modified SBR1: Pyridine group content 7.2% by mass Pyridine-modified SBR2: Pyridine group content 8.7% by mass Silica: Ultrasil VN3 (N2SA175m) from Evonik Degussa 2 / g) Carbon black: Show Black N220 (N2SA111m) manufactured by Cabot Japan Co., Ltd. 2 / g) Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads of stearic acid camellia manufactured by NOF Corporation Anti-aging agent: Antigen 3C manufactured by Sumitomo Chemical Co., Ltd. Silane coupling agent: NXT-Z45 manufactured by Momentive (a copolymer of bond unit A and bond unit B (bond unit A: 55 mol %, bond unit B: 45 mol %)) Wax: Sannock N manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Oil: H&R VIVATEC 500 (TDAE oil) Styrene-based resin: Sylvatraxx 4401 (α-methylstyrene-based resin (copolymer of α-methylstyrene and styrene), softening point 85°C) manufactured by Arizona Chemical Co. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Soxinol CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Sumitomo Chemical Co., Ltd. Vulcanization accelerator 2: Succinol D (1,3-diphenylguanidine) manufactured by Sumitomo Chemical Co., Ltd.

[0120] (Synthesis Example 1: Synthesis of organic silane compound a1 used in the modification reaction process) A 1 mol / L cyclohexane solution of 3-dimethylaminopropyltrimethoxysilane is prepared in a dried, nitrogen-substituted pressure-resistant glass vessel, and a 1 mol / L diethyl ether solution of methyllithium (MeLi) is added dropwise to the solution so as to be equimolar to the cyclohexane solution. The solution is thoroughly stirred to prepare a modifying agent solution (a1) of an organic silane compound {3-dimethylaminopropyl(dimethoxy)methylsilane}.

[0121] (Production Example 1: Production of Modified Polymers (A1) and (A2) Having Silanol Groups) <Production of conjugated diene copolymer having active terminal> A cyclohexane solution of 1,3-butadiene and a cyclohexane solution of styrene are added to a dried, nitrogen-purged pressure-resistant glass vessel, 2,2-ditetrahydrofurylpropane is added, and n-butyllithium (BuLi) is further added, and then a polymerization reaction is carried out in a warm water bath at 50°C. The polymerization conversion rate at this time is nearly 100%. <Modification reaction process> Next, the organosilane compound (a1) obtained in Synthesis Example 1 was added to the polymerization reaction system in an equimolar amount relative to lithium (Li), and the modification reaction was further carried out at 50° C. for 30 minutes. <Hydrolysis process and subsequent processes> After that, dilute hydrochloric acid is added little by little to the polymerization reaction system, and then water is added in an amount three times the molar amount of lithium (Li) and stirred for 30 minutes. Next, an isopropanol solution of 2,6-di-tert-butyl-p-cresol (BHT) is added to the polymerization reaction system to terminate the polymerization reaction. After that, water vapor is blown in to reduce the partial pressure of the solvent (steam stripping) to remove the solvent, and then the mixture is vacuum dried to obtain modified polymers (A1) and (A2) (terminally modified polymers) having silanol groups.

[0122] (Production Example 2: Production of modified polymers (A3) and (A4) having silanol groups) Cyclohexane, 1,3-butadiene, styrene, and 2,2-ditetrahydrofurylpropane are poured into a nitrogen-purged autoclave under nitrogen as a cyclohexane solution, and n-butyllithium (BuLi) is added to the solution, after which polymerization is carried out in a 50°C warm water bath equipped with a stirrer. The polymerization conversion rate is nearly 100%. The polymerization solution is then kept at a temperature of 50°C without deactivating the polymerization catalyst, and N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane having a precursor capable of generating primary amino groups by hydrolysis is added to carry out the modification reaction for 15 minutes. After this, tetrakis(2-ethyl-1,3-hexanediolato)titanium, a condensation accelerator, is added and stirred for another 15 minutes. Finally, 2,6-di-tert-butyl-p-cresol is added to the polymer solution after the reaction. Next, the solvent is removed by steam stripping and the precursor capable of generating the primary amino groups is hydrolyzed, and the rubber is dried by a heated roll adjusted to 110°C to obtain modified polymers (A3) and (A4) having silanol groups (polymers whose main chain and terminals are modified).

[0123] (Measurement of polymer modification rate) The modification rate of the polymer is calculated using the following formula. Denaturation rate (%) = (FG) / (H) x 100 (In the formula, F represents the amount of modifier added (g), G represents the amount of modifier remaining after polymerization is completed (g), and H represents the weight of the obtained polymer (g). G is calculated by taking a part of the reaction solution, precipitating the rubber with alcohol, and then calculating the ratio of the modifier remaining in the solvent using a Shimadzu Corporation gas chromatograph GC2010 (FID detector) and the calibration curve method.)

[0124] <Production conditions (rubber composition)> (Base mixing process) Using a 1.7L Banbury mixer, the materials listed in the base kneading section of each table are kneaded to obtain a kneaded product. In each table, X-1 and X-2 indicate that each material is added and kneaded in that order. The kneading temperature and kneading time for each item are as follows. X-1 (first base kneading process) Kneading temperature: 150°C, kneading time: 5 minutes X-2 (second base kneading process) Kneading temperature: 150°C, kneading time: 5 minutes (Finishing kneading process) Using an open roll, the materials specified in the finishing kneading section in each table are added to the second kneaded material obtained in the second base kneading step, and kneaded at 70°C for 8 minutes to obtain an unvulcanized rubber composition.

[0125] <Manufacturing conditions (test tires)> Unvulcanized rubber compositions are obtained in the same manner as described above. Each of the obtained unvulcanized rubber compositions is molded into a cap tread shape, laminated together with other tire components, and vulcanized at 170° C. for 15 minutes to produce a test tire (tire size: 195 / 65R15).

[0126] (Silica Dispersion Index) For the rubber composition (unvulcanized rubber composition) obtained under the above manufacturing conditions (rubber composition), ΔG* (= maximum value of G* - minimum value of G*) at dynamic strains of 0.5, 1, 2, 4, 8, 16, 32, and 64% is predicted using an RPA2000 testing machine manufactured by Alpha Technologies under conditions of 100°C and 1 Hz. ΔG* for each compound is indexed using the following formula. A higher index indicates better silica dispersibility and better temperature dependency of heat generation. (Silica dispersion index) = (ΔG* of standard comparative example / ΔG* of each formulation) × 100

[0127] (Fuel efficiency index (calculated based on actual vehicle evaluation in simulation)) Using a rolling resistance tester, the test tire manufactured under the above manufacturing conditions (test tire) was run at a speed (80 km / h) to measure the rolling resistance, and the rolling resistance was expressed as an index with the reference comparative example being taken as 100. A higher index indicates better fuel economy at a constant temperature.

[0128] [Table 1]

[0129] [Table 2]

[0130] [Table 3]

[0131] [Table 4]

[0132] As can be seen from the table, the examples containing a polymer (A) having a silanol group, a polymer (B) having a basic functional group, and silica have significantly improved silica dispersibility (temperature dependence of heat generation) and overall fuel efficiency at a constant temperature (expressed as the sum of two indices, the silica dispersion index and the fuel efficiency index), and are excellent in rolling resistance (fuel efficiency) over a wide range of temperatures.

[0133] Furthermore, a comparison between Comparative Example 1-1 (100 parts by mass of main chain terminal-modified SBR), Comparative Example 1-4 (100 parts by mass of pyridine-modified SBR), and Example 1 (50 parts by mass of main chain terminal-modified SBR and 50 parts by mass of pyridine-modified SBR) and a comparison between Comparative Example 1-3 (100 parts by mass of terminal-modified SBR), Comparative Example 1-4 (100 parts by mass of pyridine-modified SBR), and Example 2 (50 parts by mass of terminal-modified SBR and 50 parts by mass of pyridine-modified SBR) shows that the combined use of the polymer (A) having a silanol group and the polymer (B) having a basic functional group synergistically improves the overall performance.

Claims

1. A rubber composition comprising: a polymer (A) having a silanol group (excluding polymers modified with N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane); a polymer (B) having a basic functional group (excluding polymers having a silanol group and a basic functional group); silica; and a plasticizer containing a styrene-based resin, The polymer (A) has a silanol group other than at a terminal, and the polymer (B) has a tertiary amino group, the polymers (A) and (B) each have an aromatic vinyl unit derived from an aromatic vinyl compound and a conjugated diene unit derived from a conjugated diene compound, The rubber composition, wherein the polymer (A) and the polymer (B) are different polymers.

2. A rubber composition comprising: a polymer (A) having a silanol group (excluding polymers modified with N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane); a polymer (B) having a basic functional group (excluding polymers having a silanol group and a basic functional group); silica; and a plasticizer containing a styrene-based resin, the polymers (A) and (B) each have an aromatic vinyl unit derived from an aromatic vinyl compound and a conjugated diene unit derived from a conjugated diene compound, The content (parts by mass) of the plasticizer and the content (parts by mass) of the silica satisfy the following formula, 0.70≦plasticizer content / silica content≦1.10 The rubber composition, wherein the polymer (A) and the polymer (B) are different polymers.

3. A rubber composition comprising: a polymer (A) having a silanol group (excluding polymers modified with N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane); a polymer (B) having a basic functional group (excluding polymers having a silanol group and a basic functional group); silica; and a plasticizer containing a styrene-based resin, the polymers (A) and (B) each have an aromatic vinyl unit derived from an aromatic vinyl compound and a conjugated diene unit derived from a conjugated diene compound, The content (parts by mass) of the plasticizer and the content (parts by mass) of the resin satisfy the following formula, Resin content / plasticizer content≧0.50 The content of the plasticizer is 55 parts by mass or more based on 100 parts by mass of the rubber component, The rubber composition, wherein the polymer (A) and the polymer (B) are different polymers.

4. 4. The rubber composition according to claim 2, wherein the polymer (A) has a silanol group other than at the terminal, and the polymer (B) has a tertiary amino group.

5. The rubber composition according to any one of claims 1 to 4, comprising 80 parts by mass or more of silica per 100 parts by mass of the rubber component.

6. The nitrogen adsorption specific surface area of ​​silica is 170m ２ The rubber composition according to any one of claims 1 to 5, wherein the elastic modulus is 1 / g or more.

7. The rubber composition according to any one of claims 1 to 6, further comprising a mercapto-based silane coupling agent.

8. The rubber composition according to claim 1 or 2, further comprising a plasticizer containing a resin, the contents of the plasticizer and the resin satisfying the following formula: Resin content / plasticizer content≧0.50

9. The rubber composition according to claim 1 or 3, comprising a plasticizer and silica, the contents of the plasticizer and the silica satisfying the following formula: Plasticizer content / Silica content≧0.50

10. A tire using the rubber composition according to any one of claims 1 to 9.

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