Rubber composition, method for producing rubber composition, and tire

Abstract

[Problem] To provide a rubber composition that can reduce rolling resistance while improving wet performance of a tire. [Solution] This rubber composition is characterized in that: said rubber composition comprises a rubber component, a filler, and a resin; the rubber component contains natural rubber, a high-Tg modified styrene-butadiene rubber, and a low-Tg modified styrene-butadiene rubber having a lower Tg than the high-Tg modified styrene-butadiene rubber; both ends of the high-Tg modified styrene-butadiene rubber are modified and at least one end is modified with an alkoxysilane; one end of the low-Tg modified styrene-butadiene rubber is modified with an alkoxysilane; and the mass ratio between the high-Tg modified styrene-butadiene rubber (high-Tg modified SBR) content and the low-Tg modified styrene-butadiene rubber (low-Tg modified SBR) content (high-Tg modified SBR content / low-Tg-modified SBR content) is greater than 1.

Description

[Technical Field]

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

[0002] In recent years, with the rise in interest in environmental issues and the move toward global carbon dioxide emission regulations, there has been an increasing demand for improved fuel efficiency in automobiles. To meet these demands, there is also a demand for reduced rolling resistance in tires. In response to this demand, a common method for reducing tire rolling resistance has been to apply to tires rubber compositions that have a low loss tangent (tan δ) in the temperature range during normal driving (hereinafter referred to as "excellent low loss properties").

[0003] Furthermore, from the viewpoint of improving vehicle safety, it is also important to ensure braking performance on wet roads (hereinafter referred to as "wet performance"), and there is a demand for improving tire fuel economy as well as wet performance. In response to this, conventionally, tires that combine wet performance with low rolling resistance by using a rubber composition containing styrene-butadiene rubber (SBR) and silica have become mainstream. In addition, there is a method of compounding modified styrene-butadiene rubber with a high styrene content into the rubber composition used in tire tread rubber to increase the glass transition temperature (Tg) of the tire tread rubber, but there is a limit to how well it can achieve both wet performance and low rolling resistance.

[0004] On the other hand, if the amount of filler such as silica is reduced in order to improve the dispersibility of the filler in the rubber composition, the reinforcing properties of the rubber composition will be deteriorated. Furthermore, there is a method of adding a resin to a rubber composition to improve wet performance, but adding a resin increases the loss tangent (tan δ) in the temperature range during normal driving, deteriorating low loss properties and increasing the rolling resistance of a tire using the rubber composition. Furthermore, Patent Document 1 below discloses a rubber composition in which a styrene-alkylene block copolymer having a styrene content of 30% by mass or more is blended into the rubber component, and discloses that the rubber composition has excellent dry handling properties while also achieving wet performance and low loss. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 117214 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the inventors of the present invention have conducted studies and found that conventional rubber compositions such as those disclosed in Patent Document 1 have limitations in achieving both wet performance and low rolling resistance in tires, and that there is still room for improvement.

[0007] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide a rubber composition that can reduce rolling resistance while improving the wet performance of a tire, and a method for producing the same. Another object of the present invention is to provide a tire that has excellent wet performance and low rolling resistance. [Means for solving the problem]

[0008] The gist and configuration of the present invention to solve the above problems is as follows.

[0009] The rubber composition of the present invention includes a rubber component, a filler, and a resin, the rubber component includes natural rubber, a high-Tg modified styrene-butadiene rubber, and a low-Tg modified styrene-butadiene rubber having a glass transition temperature (Tg) lower than that of the high-Tg modified styrene-butadiene rubber; The high Tg modified styrene-butadiene rubber has both ends modified, and at least one end modified with an alkoxysilane, the low Tg modified styrene-butadiene rubber has one end modified with alkoxysilane, The rubber composition is characterized in that the mass ratio (content of high Tg modified SBR / content of low Tg modified SBR) of the content of the high Tg modified styrene-butadiene rubber (high Tg modified SBR) to the content of the low Tg modified styrene-butadiene rubber (low Tg modified SBR) is greater than 1.

[0010] Further, a method for producing a rubber composition of the present invention is a method for producing a rubber composition including the rubber component, the filler, the resin, a guanidine, and a vulcanizing agent, a first kneading step of kneading the rubber component, the filler, the resin, and the guanidines; a second kneading step of kneading the kneaded product obtained in the first kneading step with the vulcanizing agent; The present invention is characterized by comprising:

[0011] The tire of the present invention is characterized by comprising a tread rubber made of the above rubber composition. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a rubber composition that can improve the wet performance of a tire while reducing rolling resistance, and a method for producing the same. Furthermore, according to the present invention, a tire having excellent wet performance and low rolling resistance can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0013] The rubber composition, the method for producing the rubber composition, and the tire of the present invention will be described in detail below by way of example based on embodiments thereof.

[0014] <Rubber composition> The rubber composition of the present invention includes a rubber component, a filler, and a resin. The rubber component of the rubber composition of the present invention includes natural rubber, a high-Tg modified styrene-butadiene rubber, and a low-Tg modified styrene-butadiene rubber having a glass transition temperature (Tg) lower than that of the high-Tg modified styrene-butadiene rubber. The high-Tg modified styrene-butadiene rubber has both terminals modified, with at least one terminal modified with an alkoxysilane. The low-Tg modified styrene-butadiene rubber has one terminal modified with an alkoxysilane. The mass ratio of the content of the high-Tg modified styrene-butadiene rubber (high-Tg modified SBR) to the content of the low-Tg modified styrene-butadiene rubber (low-Tg modified SBR) (content of high-Tg modified SBR / content of low-Tg modified SBR) is greater than 1.

[0015] In the rubber composition of the present invention, the high Tg modified styrene-butadiene rubber, both ends of which have been modified, with at least one end modified with an alkoxysilane, interacts with the filler to improve the dispersibility of the filler in the rubber composition, and by applying the rubber composition to a tire, the wet performance of the tire can be improved while reducing the rolling resistance. Furthermore, the rubber composition of the present invention contains a low Tg modified styrene-butadiene rubber one end of which has been modified with an alkoxysilane, and by making the mass ratio (content of high Tg modified SBR / content of low Tg modified SBR) of the content of the high Tg modified styrene-butadiene rubber (high Tg modified SBR) to the content of the low Tg modified styrene-butadiene rubber (low Tg modified SBR) greater than 1, the wet performance of a tire to which the rubber composition is applied can be significantly improved. Therefore, when the rubber composition of the present invention is applied to a tire, it is possible to reduce the rolling resistance of the tire and to significantly improve the wet performance.

[0016] (rubber component) The rubber component of the rubber composition of the present invention contains natural rubber, a high-Tg modified styrene-butadiene rubber, and a low-Tg modified styrene-butadiene rubber having a glass transition temperature (Tg) lower than that of the high-Tg modified styrene-butadiene rubber, and may further contain other rubber components. The rubber component contains two or more types of modified styrene-butadiene rubbers having different glass transition temperatures (Tg). Here, the mass ratio of the content of the high Tg modified styrene-butadiene rubber (high Tg modified SBR) to the content of the low Tg modified styrene-butadiene rubber (low Tg modified SBR) (content of high Tg modified SBR / content of low Tg modified SBR) is greater than 1. The inclusion of a high-Tg modified SBR modified at both ends or a low-Tg modified SBR modified at one end as the rubber component can improve the dispersibility of the filler in the rubber composition, and by applying the rubber composition to a tire, the rolling resistance of the tire can be reduced without deteriorating the wet performance. Furthermore, by optimizing the mass ratio of the high-Tg modified SBR to the low-Tg modified SBR in the rubber component, the wet performance of the tire using the rubber composition can be further improved without deteriorating the rolling resistance.

[0017] The high-Tg modified styrene-butadiene rubber has both terminals modified, with at least one terminal modified with an alkoxysilane, and the low-Tg modified styrene-butadiene rubber has one terminal modified with an alkoxysilane. Here, "alkoxysilane" is a general term for compounds having at least one alkoxy group and at least one silicon atom. The alkoxysilane preferably contains at least one nitrogen atom. Examples of the nitrogen atom-containing group include a functional group selected from the group consisting of a primary amino group, a primary amino group protected with a hydrolyzable protecting group, an onium salt residue of a primary amine, an isocyanate group, a thioisocyanate group, an imine group, an imine residue, an amide group, a secondary amino group protected with a hydrolyzable protecting group, a cyclic secondary amino group, an onium salt residue of a cyclic secondary amine, an acyclic secondary amino group, an onium salt residue of an acyclic secondary amine, an isocyanuric acid triester residue, a cyclic tertiary amino group, an acyclic tertiary amino group, a nitrile group, a pyridine residue, an onium salt residue of a cyclic tertiary amine, and an onium salt residue of an acyclic tertiary amine, and a monovalent hydrocarbon group having 1 to 30 carbon atoms and including a linear, branched, alicyclic, or aromatic ring, or a monovalent hydrocarbon group having 1 to 30 carbon atoms and including at least one heteroatom selected from an oxygen atom, a sulfur atom, and a phosphorus atom.

[0018] --Natural rubber-- The rubber component contains natural rubber. The proportion of natural rubber in the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and preferably 60% by mass or less, more preferably 50% by mass or less. By making the proportion of natural rubber in the rubber component 10% by mass or more, the excellent physical properties of natural rubber are further exhibited, and the wet performance of a tire using the rubber composition can be further improved and the rolling resistance can be further reduced. Furthermore, if the proportion of natural rubber in the rubber component is 60% by mass or less, the proportion of high Tg modified SBR or low Tg modified SBR, which will be described later, can be increased.

[0019] --High Tg Modified SBR-- The high Tg modified styrene-butadiene rubber (sometimes abbreviated as "high Tg modified SBR") has a higher glass transition temperature (Tg) than the low Tg modified styrene-butadiene rubber described below. That is, the terms "high Tg" and "low Tg" in the high Tg modified styrene-butadiene rubber and the low Tg modified styrene-butadiene rubber indicate that one modified styrene-butadiene rubber has a relatively higher or lower glass transition temperature (Tg) than the other modified styrene-butadiene rubber, and do not indicate that the glass transition temperature (Tg) is higher or lower than a certain temperature. The high Tg modified styrene-butadiene rubber preferably has a glass transition point (Tg) of −5° C. to −35° C., more preferably −10° C. to −30° C. The high Tg of the high Tg modified SBR increases the affinity with the filler, and better dispersibility of the filler can be obtained.

[0020] The high-Tg modified styrene-butadiene rubber has both terminals modified, with at least one terminal modified with an alkoxysilane. The high-Tg modified SBR can be produced by reacting various alkoxysilanes (modifiers) with the terminals of SBR having active terminals, for example, according to the methods described in International Publication No. 2003 / 046020 and Japanese Patent Application Laid-Open No. 2007-217562.

[0021] Here, the modifier for obtaining the high Tg modified SBR is not particularly limited, but it is preferable to use a modifier containing a compound (alkoxysilane) represented by the following general formula (2). [ka]

[0022] The use of a styrene-butadiene rubber modified with a modifier containing a compound represented by the general formula (2) containing an oligosiloxane, which is a filler affinity functional group, and a tertiary amino group as the rubber component can enhance the dispersibility of fillers such as silica. As a result, the rubber composition of the present invention has improved filler dispersibility, which significantly improves low loss properties and reduces the rolling resistance of tires using the rubber composition.

[0023] In the above general formula (2), R 5 ~R 12 are each independently an alkyl group having 1 to 20 carbon atoms; L 1 and L 2 are each independently an alkylene group having 1 to 20 carbon atoms; and n is an integer of 2 to 4.

[0024] Specifically, in formula (2), R 5 ~R 8 may each independently represent a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, and 5 ~R 8 When substituted, each independently may be substituted with one or more substituents selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkoxy group having 4 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, an alkanoyloxy group having 2 to 12 carbon atoms (Ra-COO-, where Ra is an alkyl group having 1 to 9 carbon atoms), an aralkyloxy group having 7 to 13 carbon atoms, an arylalkyl group having 7 to 13 carbon atoms, and an alkylaryl group having 7 to 13 carbon atoms. More specifically, the R 5 ~R 8 may be a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and more specifically, 5 ~R 8 may each independently be a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms.

[0025] In addition, in formula (2), R 9 ~R12 are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, specifically a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, more specifically a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and when substituted, they are first 5 ~R 8 It may be substituted with substituents as described above. In addition, the above R 9 ~R 12 If is not an alkyl group but a hydrolyzable substituent, NR 9 R 10 and NR 11 R 12 The bond can be hydrolyzed to NH in the presence of moisture, adversely affecting the processability of the polymer.

[0026] More specifically, in the compound represented by the formula (2), R 5 ~R 8 is a methyl group or an ethyl group, and R 9 ~R 12 can be an alkyl group having 1 to 10 carbon atoms.

[0027] The amino group in the compound represented by the formula (2), i.e., NR 9 R 10 and NR 11 R 12 is preferably a tertiary amino group. The tertiary amino group provides the compound represented by formula (2) with better processability when used as a modifying agent. In addition, the above R 9 ~R 12If a protecting group for protecting the amino group is bonded to the terminal end of the polymer or if hydrogen is bonded to the terminal end of the polymer, it may be difficult to realize the effect of the compound represented by formula (2). If hydrogen is bonded, the anion reacts with hydrogen during the modification process, losing its reactivity and making the modification reaction impossible. If a protecting group is bonded, the modification reaction will occur, but the terminal end of the polymer will be deprotected by hydrolysis during post-processing to become a primary or secondary amino group. The deprotected primary or secondary amino group may cause the compound to become viscous during subsequent blending, potentially resulting in reduced processability.

[0028] In addition, L in the compound represented by the formula (2) 1 and L 2 are each independently a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms. More specifically, L 1 and L 2 may each independently be an alkylene group having 1 to 10 carbon atoms, more specifically, an alkylene group having 1 to 6 carbon atoms such as a methylene group, an ethylene group, or a propylene group.

[0029] L in the compound represented by formula (2) 1 and L 2 Regarding the above, the shorter the distance between the Si atom and the N atom in the molecule, the better the effect. However, if Si is directly bonded to N, there is a risk that the bond between Si and N will break during the subsequent processing step, and the secondary amino group generated in this case is likely to be washed away by water during the post-processing. In the modified SBR produced, it is difficult for the amino group, which promotes bonding with fillers such as silica, to bond with the filler, and as a result, the effect of improving the dispersibility of the filler may be reduced. In this way, considering the improvement effect depending on the bond length between Si and N, the above L 1 and L 2 More preferably, each of L is independently an alkylene group having 1 to 3 carbon atoms, such as a methylene group, an ethylene group, or a propylene group, and more specifically, can be a propylene group. 1 and L 2 R first 5 ~R8 It may be substituted with substituents as described above.

[0030] The compound represented by the formula (2) is preferably, for example, any one of the compounds represented by the following structural formulas (2-1) to (2-5), because this allows for the realization of even better low loss properties. [ka]

[0031] The compound represented by formula (2) has an alkoxysilane structure that bonds to the active terminal of SBR, while the Si-O-Si structure and three or more amino groups bonded to the terminals exhibit affinity for fillers such as silica, thereby promoting bonding between the filler and modified SBR compared to conventional modifiers containing only one amino group per molecule. Furthermore, the degree of bonding at the active terminal of the SBR is uniform, and when observing the change in molecular weight distribution before and after coupling, the molecular weight distribution remains constant without increasing compared to before coupling. Therefore, there is no deterioration in the physical properties of the modified SBR itself, and filler aggregation in the rubber composition can be prevented, improving filler dispersibility and improving the processability of the rubber composition. These effects, particularly when the rubber composition is applied to tires, enable a balanced improvement in rolling resistance and wet performance.

[0032] The compound represented by the formula (2) can be produced through a condensation reaction represented by the following reaction scheme. [ka]

[0033] In the above reaction scheme, R 5 ~R 12 , L 1 and L 2 and n are the same as those defined in the above formula (2), and R′ and R″ are any substituents that do not affect the condensation reaction. For example, R′ and R″ are each independently R 5~R 8 It can be identical to any one of the following:

[0034] The reaction of the above reaction scheme proceeds in the presence of an acid, and any acid generally used in condensation reactions can be used without limitation. Those skilled in the art can select an optimal acid depending on various process variables such as the type of reactor in which the reaction is carried out, starting materials, and reaction temperature.

[0035] The modified SBR modified with a modifier containing the compound represented by formula (2) can have a narrow molecular weight distribution (Mw / Mn, also referred to as the "polydispersity index (PDI)") of 1.1 to 3.0. If the molecular weight distribution of the modified SBR exceeds 3.0 or is less than 1.1, there is a risk of deterioration in tensile properties and viscoelasticity when applied to a rubber composition. Considering the remarkable effect of improving tensile properties and viscoelasticity by controlling the molecular weight distribution of the modified SBR, the molecular weight distribution of the modified SBR is preferably in the range of 1.3 to 2.0. By using the modifier, the modified SBR has a molecular weight distribution similar to that of the styrene-butadiene rubber before modification.

[0036] The molecular weight distribution of the modified SBR can be calculated from the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn). Here, the number average molecular weight (Mn) is the common average of the molecular weights of individual polymers calculated by measuring the molecular weights of n polymer molecules, summing these molecular weights, and dividing by n. The weight average molecular weight (Mw) represents the molecular weight distribution of the polymer composition. The average of the total molecular weight can be expressed in grams per mole (g / mol). The weight average molecular weight and number average molecular weight are each a polystyrene-equivalent molecular weight analyzed by gel permeation chromatography (GPC).

[0037] The modified SBR satisfies the above-mentioned molecular weight distribution conditions and may have a number average molecular weight (Mn) of 50,000 g / mol to 2,000,000 g / mol, more specifically, 200,000 g / mol to 800,000 g / mol, and a weight average molecular weight (Mw) of 100,000 g / mol to 4,000,000 g / mol, more specifically, 300,000 g / mol to 1,500,000 g / mol. If the weight-average molecular weight (Mw) of the modified SBR is less than 100,000 g / mol or the number-average molecular weight (Mn) is less than 50,000 g / mol, the tensile properties may be reduced when applied to a rubber composition. On the other hand, if the weight-average molecular weight (Mw) is more than 4,000,000 g / mol or the number-average molecular weight (Mn) is more than 2,000,000 g / mol, the processability of the modified SBR may be reduced, resulting in a deterioration in the workability of the rubber composition, making kneading difficult, and making it difficult to sufficiently improve the physical properties of the rubber composition. More specifically, when the modified SBR satisfies the requirements for weight average molecular weight (Mw) and number average molecular weight (Mn) as well as the molecular weight distribution, when the modified SBR is applied to a rubber composition, it can improve the viscoelasticity and processability of the rubber composition in a well-balanced manner.

[0038] The modified SBR preferably has a vinyl bond content in the butadiene moiety of 5% or more, more preferably 10% or more, and preferably 60% or less. By adjusting the vinyl bond content in the butadiene moiety to fall within the above range, the glass transition temperature can be adjusted to an appropriate range.

[0039] The modified SBR may have a Mooney viscosity (MV) at 100° C. of 40 to 140, specifically 60 to 100. When the modified SBR has a Mooney viscosity in the above range, it can exhibit better processability. The Mooney viscosity can be measured using a Mooney viscometer, such as Monsanto's MV2000E, at 100°C, a rotor speed of 2±0.02 rpm, and a large rotor. The sample used here is left at room temperature (23±3°C) for 30 minutes or more, and then 27±3 g of the sample is taken and filled into the die cavity, and the platen is operated to measure the viscosity.

[0040] As described above, the high-Tg modified SBR is preferably modified at one end with a modifier containing a compound represented by the above general formula (2), and more preferably further modified at the other end with a modifier containing a compound represented by the following general formula (3): By modifying both ends of the high-Tg modified SBR, the dispersibility of the filler in the rubber composition is further improved, and a tire using the rubber composition can achieve both low rolling resistance and wet performance at a higher level. [ka]

[0041] In the above general formula (3), R 13 ~R 15 are each independently hydrogen; an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms, a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; or a heterocyclic group having 3 to 30 carbon atoms. Also, in formula (3), R 16 represents a single bond; an alkylene group having 1 to 20 carbon atoms which is substituted or unsubstituted; a cycloalkylene group having 5 to 20 carbon atoms which is substituted or unsubstituted; or an arylene group having 5 to 20 carbon atoms which is substituted or unsubstituted, wherein the substituent is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. Also, in formula (3), R 17is an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; a heterocyclic group having 3 to 30 carbon atoms; or a functional group represented by the following general formula (3a) or general formula (3b), wherein m is an integer of 1 to 5, and R 17 At least one of the functional groups is represented by the following general formula (3a) or (3b), and when m is an integer of 2 to 5, a plurality of R 17 may be the same as or different from each other.

[0042] [ka]

[0043] In the above general formula (3a), R 17a1 represents a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms; a substituted or unsubstituted cycloalkylene group having 5 to 20 carbon atoms; or a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, wherein the substituent is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. Also, in formula (3a), R 17a2 and R 17a3 are each independently an alkylene group having 1 to 20 carbon atoms which is substituted or unsubstituted with an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. Also, in formula (3a), R 17a4 is hydrogen; an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; or a heterocyclic group having 3 to 30 carbon atoms; and X is an N, O, or S atom, provided that when X is O or S, R 17a4 does not exist.

[0044] [ka]

[0045] In the above general formula (3b), R 17b1 represents a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms; a substituted or unsubstituted cycloalkylene group having 5 to 20 carbon atoms; or a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, wherein the substituent is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. Also, in formula (3b), R 17b2 and R 17b3 are each independently an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; or a heterocyclic group having 3 to 30 carbon atoms.

[0046] In addition, in the compound represented by the general formula (3), R 13 ~R 15 are each independently hydrogen; an alkyl group having 1 to 10 carbon atoms; an alkenyl group having 2 to 10 carbon atoms; or an alkynyl group having 2 to 10 carbon atoms; and R 16 is a single bond; or an unsubstituted alkylene group having 1 to 10 carbon atoms, and R 17 is an alkyl group having 1 to 10 carbon atoms; an alkenyl group having 2 to 10 carbon atoms; an alkynyl group having 2 to 10 carbon atoms; or a functional group represented by the above general formula (3a) or general formula (3b), and in the above general formula (3a), R 17a1 is an unsubstituted alkylene group having 1 to 10 carbon atoms, and R 17a2 and R 17a3 are each independently an unsubstituted alkylene group having 1 to 10 carbon atoms, and R 17a4is an alkyl group having 1 to 10 carbon atoms; a cycloalkyl group having 5 to 20 carbon atoms; an aryl group having 6 to 20 carbon atoms; or a heterocyclic group having 3 to 20 carbon atoms, and in the above general formula (3b), R 17b1 is an unsubstituted alkylene group having 1 to 10 carbon atoms, and R 17b2 and R 17b3 may each independently be an alkyl group having 1 to 10 carbon atoms; a cycloalkyl group having 5 to 20 carbon atoms; an aryl group having 6 to 20 carbon atoms; or a heterocyclic group having 3 to 20 carbon atoms.

[0047] More specifically, the compound represented by the above general formula (3) can be a compound represented by the following structural formulas (3-1) to (3-3). [ka]

[0048] When the styrene-butadiene rubber is modified with a modifying agent containing the compound represented by the general formula (3), the modifying agent containing the compound represented by the formula (3) is used as a modification initiator. Specifically, for example, by polymerizing a butadiene monomer and a styrene monomer in a hydrocarbon solvent in the presence of a modifying agent containing a compound represented by formula (3), a modifying group derived from the compound represented by formula (3) can be imparted to the styrene-butadiene rubber.

[0049] The proportion of the high Tg modified SBR in the rubber component is selected so that the mass ratio (content of high Tg modified SBR / content of low Tg modified SBR) is greater than 1, and is preferably 20% by mass or more, more preferably 30% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less. By setting the proportion of the high Tg modified SBR in the rubber component to 20% by mass or more, the wet performance of a tire using the rubber composition can be further improved and the rolling resistance can be further reduced. Furthermore, if the proportion of the high Tg modified SBR in the rubber component is 70% by mass or less, the proportion of the above-mentioned natural rubber and the below-mentioned low Tg modified SBR can be increased.

[0050] --Low Tg Modified SBR-- The low Tg modified styrene-butadiene rubber (sometimes abbreviated as "low Tg modified SBR") has a lower glass transition temperature (Tg) than the high Tg modified styrene-butadiene rubber. That is, the terms "high Tg" and "low Tg" in the high Tg modified styrene-butadiene rubber and the low Tg modified styrene-butadiene rubber indicate that one modified styrene-butadiene rubber has a relatively higher or lower glass transition temperature (Tg) than the other modified styrene-butadiene rubber, and do not indicate that the glass transition temperature (Tg) is higher or lower than a certain temperature. The low Tg modified styrene-butadiene rubber preferably has a glass transition point (Tg) of −75° C. to −45° C., more preferably −70° C. to −50° C. The low Tg of the low Tg modified SBR can further improve the balance between low loss properties and wet performance. The difference in glass transition temperature (Tg) between the low-Tg modified SBR and the above-mentioned high-Tg modified SBR is preferably at least 30° C., more preferably at least 35° C., and is preferably at most 60° C., more preferably at most 50° C. When the difference in glass transition temperature (Tg) is within this range, the effect of including multiple types of modified SBR with different Tg becomes significant, and the balance between low loss properties and wet performance can be further improved.

[0051] The low Tg modified styrene-butadiene rubber has one end modified with an alkoxysilane. The other end of the low Tg modified styrene-butadiene rubber may be modified with a substance other than the alkoxysilane, but is preferably unmodified. Here, "the other end is unmodified" means that the other end does not have a functional group and is composed of a hydrocarbon group. The low Tg modified styrene-butadiene rubber can be produced, for example, by reacting various alkoxysilanes (modifiers) with the terminals of SBR having active terminals according to the methods described in WO 2003 / 046020 and JP 2007-217562 A.

[0052] The modifier for obtaining the low Tg modified SBR is not particularly limited, but is preferably an alkoxysilane compound represented by the following general formula (4). R 19 a -Si-(OR 20 ) 4-a (4)

[0053] In general formula (4), R 19 and R 20 each independently represents a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, a is an integer of 0 to 2, OR 20 If there are multiple, each OR 20 may be the same or different, and the molecule does not contain any active protons.

[0054] The modifier for obtaining the low Tg modified SBR is also preferably an aminoalkoxysilane compound represented by the following general formula (5). [ka]

[0055] In the general formula (5), n1+n2+n3+n4=4 (wherein n2 is an integer of 1 to 4, and n1, n3 and n4 are integers of 0 to 3). A 1 is at least one functional group selected from a saturated cyclic tertiary amine compound residue, an unsaturated cyclic tertiary amine compound residue, a ketimine residue, a nitrile group, a (thio)isocyanate group, an isocyanuric acid trihydrocarbyl ester group, a nitrile group, a pyridine group, a (thio)ketone group, an amide group, and a primary or secondary amino group having a hydrolyzable group. When n4 is 2 or more, A 1 may be the same or different, and A 1 may be a divalent group that bonds with Si to form a cyclic structure. R 21represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when n1 is 2 or more, may be the same or different. R 23 represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a halogen atom, and when n3 is 2 or greater, may be the same or different. R 22 is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, both of which may contain a nitrogen atom and / or a silicon atom. When n2 is 2 or more, R 22 may be the same or different from each other, or may be joined together to form a ring. R 24 represents a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when n4 is 2 or more, may be the same or different.

[0056] The hydrolyzable group in the hydrolyzable group-containing primary or secondary amino group is preferably a trimethylsilyl group or a tert-butyldimethylsilyl group, and particularly preferably a trimethylsilyl group.

[0057] The aminoalkoxysilane compound represented by the above general formula (5) is preferably an aminoalkoxysilane compound represented by the following general formula (6). [ka]

[0058] In the general formula (6), p1+p2+p3=2 (wherein p2 is an integer of 1 or 2, and p1 and p3 are integers of 0 or 1). A 2 is NRa (Ra is a monovalent hydrocarbon group, a hydrolyzable group, or a nitrogen-containing organic group). R 25is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 27 is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a halogen atom. R 26 is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a nitrogen-containing organic group, any of which may contain a nitrogen atom and / or a silicon atom. 26 may be the same or different, or may be joined together to form a ring. R 28 is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. The hydrolyzable group is preferably a trimethylsilyl group or a tert-butyldimethylsilyl group, and particularly preferably a trimethylsilyl group.

[0059] The aminoalkoxysilane compound represented by the above general formula (5) is also preferably an aminoalkoxysilane compound represented by the following general formula (7) or (8). [ka]

[0060] In the general formula (7), q1+q2=3 (wherein q1 is an integer of 0 to 2, and q2 is an integer of 1 to 3). R 31 is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 32 and R 33 are each independently a hydrolyzable group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 34represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when q1 is 2, may be the same or different. R 35 represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when q2 is 2 or more, may be the same or different.

[0061] [ka]

[0062] In the general formula (8), r1+r2=3 (where r1 is an integer of 1 to 3, and r2 is an integer of 0 to 2). R 36 is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 37 are a dimethylaminomethyl group, a dimethylaminoethyl group, a diethylaminomethyl group, a diethylaminoethyl group, a methylsilyl(methyl)aminomethyl group, a methylsilyl(methyl)aminoethyl group, a methylsilyl(ethyl)aminomethyl group, a methylsilyl(ethyl)aminoethyl group, a dimethylsilylaminomethyl group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and may be the same or different when r1 is 2 or greater. R 38 represents a hydrocarbyloxy group having 1 to 20 carbon atoms, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when r2 is 2, may be the same or different. A specific example of the aminoalkoxysilane compound represented by the general formula (8) is N-(1,3-dimethylbutylidene)-3-triethoxysilyl-1-propanamine.

[0063] The aminoalkoxysilane compound represented by the above general formula (5) is also preferably an aminoalkoxysilane compound represented by the following general formula (9) or (10). [ka]

[0064] In general formula (9), R 40 is a trimethylsilyl group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and R 41 is a hydrocarbyloxy group having 1 to 20 carbon atoms, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and R 42 is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, where TMS represents a trimethylsilyl group (the same applies hereinafter).

[0065] [ka]

[0066] In general formula (10), R 43 and R 44 are each independently a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and R 45 is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and each R 45 may be the same or different.

[0067] The aminoalkoxysilane compound represented by the above general formula (5) is also preferably an aminoalkoxysilane compound represented by the following general formula (11) or (12). [ka]

[0068] In the general formula (11), s1+s2 is 3 (wherein s1 is an integer of 0 to 2, and s2 is an integer of 1 to 3), and R 46 is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and R 47 and R 48 are each independently a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. 47 or R 48 may be the same or different.

[0069] [ka]

[0070] In the general formula (12), X is a halogen atom, and R 49 is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and R 50 and R 51 are each independently a hydrolyzable group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or R 50 and R 51 are bonded to form a divalent organic group, and R 52 and R 53 R are each independently a halogen atom, a hydrocarbyloxy group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. 50 and R 51 is preferably a hydrolyzable group, and as the hydrolyzable group, a trimethylsilyl group or a tert-butyldimethylsilyl group is preferred, with a trimethylsilyl group being particularly preferred.

[0071] The aminoalkoxysilane compound represented by the above general formula (5) is also preferably an aminoalkoxysilane compound represented by the following general formula (13), the following general formula (14), the following general formula (15), or the following general formula (16). [ka] [ka] [ka] [ka]

[0072] In the general formulas (13) to (16), the symbols U and V are each an integer of 0 to 2 and satisfy U+V=2. 54 ~ 92 may be the same or different and are monovalent or divalent aliphatic or alicyclic hydrocarbon groups having 1 to 20 carbon atoms, or monovalent or divalent aromatic hydrocarbon groups having 6 to 18 carbon atoms. α and β in general formula (16) are integers of 0 to 5.

[0073] Among the compounds satisfying general formula (13), general formula (14), and general formula (15), N1,N1,N7,N7-tetramethyl-4-((trimethoxysilyl)methyl)heptane-1,7-diamine, 2-((hexyl-dimethoxysilyl)methyl)-N1,N1,N3,N3-2-pentamethylpropane-1,3-diamine, N1-(3-(dimethylamino)propyl)-N3,N3-dimethyl-N1-(3-(trimethoxysilyl)propyl)propane-1,3-diamine, and 4-(3-(dimethylamino)propyl)-N1,N1,N7,N7-tetramethyl-4-((trimethoxysilyl)methyl)heptane-1,7-diamine are particularly preferred. Furthermore, among the compounds satisfying the general formula (16), N,N-dimethyl-2-(3-(dimethoxymethylsilyl)propoxy)ethanamine, N,N-bis(trimethylsilyl)-2-(3-(trimethoxysilyl)propoxy)ethanamine, N,N-dimethyl-2-(3-(trimethoxysilyl)propoxy)ethanamine, and N,N-dimethyl-3-(3-(trimethoxysilyl)propoxy)propan-1-amine are particularly preferred.

[0074] The proportion of the low Tg modified SBR in the rubber component is selected so that the mass ratio (content of high Tg modified SBR / content of low Tg modified SBR) is greater than 1, and is preferably 5% by mass or more, more preferably 10% by mass or more, and is preferably 45% by mass or less, more preferably 40% by mass or less. By setting the proportion of the low Tg modified SBR in the rubber component to 5% by mass or more, the wet performance of a tire using the rubber composition can be further improved and the rolling resistance can be further reduced. Furthermore, if the proportion of the low Tg modified SBR in the rubber component is 45% by mass or less, the proportion of the natural rubber and high Tg modified SBR can be increased.

[0075] The mass ratio of the content of the high Tg modified styrene-butadiene rubber (high Tg modified SBR) to the content of the low Tg modified styrene-butadiene rubber (low Tg modified SBR) (content of high Tg modified SBR / content of low Tg modified SBR) is greater than 1, preferably 1.1 or more, more preferably 1.2 or more, and is preferably 3 or less, more preferably 2.8 or less. When the mass ratio (content of high Tg modified SBR / content of low Tg modified SBR) is within the preferred range, the dispersibility of the filler is further improved, and the wet performance of a tire using the rubber composition can be further improved without deteriorating the rolling resistance.

[0076] --Other rubber components-- The rubber component may further contain other rubber components in addition to the above-mentioned natural rubber (NR), high Tg modified SBR, and low Tg modified SBR. Examples of such other rubber components include butadiene rubber (BR), isoprene rubber (IR), butyl rubber (IIR), and ethylene-propylene copolymer. These other rubber components may be used alone or as a blend of two or more. When the other rubber component is contained, the proportion of the other rubber component in the rubber component is preferably 10% by mass or less, more preferably 5% by mass or less, and may be 0% by mass.

[0077] (filler) The rubber composition of the present invention contains a filler, which improves the reinforcing properties of the rubber composition. The content of the filler in the rubber composition is preferably in the range of 40 to 125 parts by mass per 100 parts by mass of the rubber component. When the content of the filler in the rubber composition is 40 parts by mass or more per 100 parts by mass of the rubber component, the rubber composition is sufficiently reinforced and the wear resistance of a tire using the rubber composition is improved, and when the content is 125 parts by mass or less, the modulus of elasticity of the rubber composition does not become too high and the wet performance of a tire using the rubber composition is improved. From the viewpoint of further improving the abrasion resistance of the tire, the content of the filler in the rubber composition is preferably 48 parts by mass or more, more preferably 53 parts by mass or more, more preferably 58 parts by mass or more, and even more preferably 62 parts by mass or more, per 100 parts by mass of the rubber component. Also, from the viewpoint of further improving the wet performance of the tire, the content of the filler in the rubber composition is preferably 105 parts by mass or less, preferably 100 parts by mass or less, more preferably 95 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 85 parts by mass or less, per 100 parts by mass of the rubber component.

[0078] --silica-- The filler preferably contains silica and has a nitrogen adsorption specific surface area (BET method) of 90 m 2 / g or more 330m 2 It is particularly preferred that the filler contains silica having a silica content of less than 1 / g. When the filler contains silica, the wet performance of a tire using the rubber composition can be further improved. The nitrogen adsorption specific surface area of ​​silica (BET method) is 90m 2 / g or more, the wear resistance of a tire to which the rubber composition is applied can be further improved. 2 When the tensile strength is less than 1 / g, the wet performance of a tire using the rubber composition can be further improved. In addition, from the viewpoint of further improving the wear resistance of tires using the rubber composition, the nitrogen adsorption specific surface area (BET method) of silica is 90 m 2 / g or more is more preferable, and 95m 2 / g or more is more preferable, and 150m 2 / g or more is more preferable, and 170m 2 / g or more is more preferable, and 180m 2 / g or more is more preferable, and 190m 2 / g or more is more preferable, and 195m 2 From the viewpoint of further improving the wet performance of a tire using the rubber composition, the nitrogen adsorption specific surface area (BET method) of silica is more preferably 300 m 2 / g or less is more preferable, and 280m 2 / g or less is more preferable, and 270m 2 / g or less is more preferable, and 250m 2 It is more preferable that the saturation coefficient is 1 / g or less.

[0079] Examples of the silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate. Among these, wet silica is preferred. These silicas may be used alone or in combination of two or more.

[0080] From the viewpoint of further improving the wet performance of the tire, the content of silica in the rubber composition is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 55 parts by mass or more, per 100 parts by mass of the rubber component. Also, from the viewpoint of further improving the wet performance of the tire, the content of silica in the rubber composition is preferably 108 parts by mass or less, more preferably 100 parts by mass or less, more 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, per 100 parts by mass of the rubber component.

[0081] --Carbon Black-- The filler preferably contains carbon black, which reinforces the vulcanized rubber and improves its abrasion resistance. The carbon black is not particularly limited, and examples thereof include GPF, FEF, HAF, ISAF, and SAF grade carbon black. These carbon blacks may be used alone or in combination of two or more.

[0082] From the viewpoint of further improving the abrasion resistance of a tire using the rubber composition, the content of carbon black in the rubber composition is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 4 parts by mass or more, per 100 parts by mass of the rubber component. Also, from the viewpoint of the rolling performance of a tire using the rubber composition, the content of carbon black in the rubber composition is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less, per 100 parts by mass of the rubber component.

[0083] --Aluminum hydroxide-- The filler preferably contains aluminum hydroxide. When the filler contains aluminum hydroxide, the wet performance of a tire using the rubber composition can be further improved.

[0084] From the viewpoint of further improving the wet performance of a tire using the rubber composition, the content of aluminum hydroxide in the rubber composition is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. Also, from the viewpoint of workability of the rubber composition, the content of aluminum hydroxide in the rubber composition is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the rubber component.

[0085] --Other fillers-- The filler may contain inorganic fillers such as clay, talc, calcium carbonate, etc. in addition to silica, carbon black, and aluminum hydroxide.

[0086] The above-mentioned carbon black, aluminum hydroxide, and other fillers are preferably contained in such a range that the silica content in the filler is 70% by mass or more. By containing the silica content in the filler at 70% by mass or more, the wet performance of a tire using the rubber composition can be further improved. More preferably, the silica content in the filler is 80% by mass or more, even more preferably, the silica content in the filler is 85% by mass or more, and even more preferably, the silica content in the filler is 90% by mass or more but less than 100%.

[0087] (resin) The rubber composition of the present invention contains a resin, which increases hysteresis loss in the low temperature region and improves the wet performance of a tire to which the rubber composition is applied.

[0088] The content of the resin is preferably 2 to 15 parts by mass per 100 parts by mass of the rubber component. When the content of the resin in the rubber composition is 2 parts by mass or more per 100 parts by mass of the rubber component, the effect of the resin can be fully exhibited, and when it is 15 parts by mass or less, the resin is less likely to precipitate from the rubber composition, and the effect of the resin can be fully exhibited. Therefore, when the content of the resin is 2 to 15 parts by mass, the wet performance of a tire using the rubber composition can be further improved. From the viewpoint of further enhancing the effects of the resin, the content of the resin in the rubber composition is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, and more preferably 9 parts by mass or more, per 100 parts by mass of the rubber component. Also, from the viewpoint of suppressing precipitation of the resin from the tire and suppressing deterioration of the tire appearance, the content of the resin in the rubber composition is preferably 14 parts by mass or less, more preferably 13 parts by mass or less, more preferably 12 parts by mass or less, and more preferably 11 parts by mass or less, per 100 parts by mass of the rubber component.

[0089] --Hydrogenated Resin-- The resin preferably contains a hydrogenated resin having a softening point higher than 110°C and a weight-average molecular weight in polystyrene equivalent of 200 to 1600 g / mol. The hydrogenated resin has high compatibility with the rubber component, controls the mobility of the rubber component, and can selectively improve hysteresis loss (tan δ) in the low temperature range while maintaining hysteresis loss (tan δ) in the temperature range during normal driving, thereby further improving the balance between low rolling resistance and wet performance of tires using the rubber composition.

[0090] If the softening point of the hydrogenated resin is higher than 110°C, the tire to which the rubber composition is applied can be sufficiently reinforced, and the wear resistance can be further improved. From the viewpoint of the wear resistance of the tire, the softening point of the hydrogenated resin is preferably 116°C or higher, more preferably 120°C or higher, more preferably 123°C or higher, and even more preferably 127°C or higher. Furthermore, from the viewpoint of processability, the softening point of the hydrogenated resin is preferably 160°C or lower, more preferably 150°C or lower, more preferably 145°C or lower, and even more preferably 141°C or lower.

[0091] Furthermore, when the weight average molecular weight of the hydrogenated resin in terms of polystyrene is 200 g / mol or more, the hydrogenated resin is less likely to precipitate from the rubber composition, and the effects of the hydrogenated resin can be fully exhibited. When the weight average molecular weight is 1600 g / mol or less, the hydrogenated resin is compatible with the rubber component. From the viewpoint of suppressing precipitation of the hydrogenated resin from the rubber composition and suppressing deterioration in tire appearance, the weight average molecular weight of the hydrogenated resin in terms of polystyrene is more preferably 500 g / mol or more, more preferably 550 g / mol or more, more preferably 600 g / mol or more, more preferably 650 g / mol or more, and even more preferably 700 g / mol or more. Furthermore, from the viewpoint of improving the compatibility of the hydrogenated resin with the rubber component and further enhancing the effects of the hydrogenated resin, the polystyrene-equivalent weight average molecular weight of the hydrogenated resin is more preferably 1570 g / mol or less, more preferably 1530 g / mol or less, more preferably 1500 g / mol or less, more preferably 1470 g / mol or less, more preferably 1430 g / mol or less, more preferably 1400 g / mol or less, more preferably 1370 g / mol or less, more preferably 1330 g / mol or less, more preferably 1300 g / mol or less, more preferably 1200 g / mol or less, more preferably 1100 g / mol or less, more preferably 1000 g / mol or less, and even more preferably 950 g / mol or less.

[0092] The weight average molecular weight (Mw HR ) (unit: g / mol) versus the softening point (Ts HR ) (unit: °C) ratio (Ts HR / Mw HR ) is preferably 0.07 or more, more preferably 0.083 or more, more preferably 0.095 or more, more preferably 0.104 or more, and even more preferably 0.14 or more. HR / Mw HR ) is preferably 0.19 or less, more preferably 0.18 or less, and even more preferably 0.17 or less. The softening point and polystyrene-equivalent weight average molecular weight of the hydrogenated resin can be determined by the method described in the examples below.

[0093] The hydrogenated resin means a resin obtained by reducing and hydrogenating a resin. Examples of resins that can be used as raw materials for hydrogenated resins include C5 resins, C5-C9 resins, C9 resins, terpene resins, dicyclopentadiene resins, and terpene-aromatic compound resins. These resins may be used alone or in combination of two or more.

[0094] Examples of the C5 resin include aliphatic petroleum resins obtained by (co)polymerizing C5 fractions obtained by thermal cracking of naphtha in the petrochemical industry. The C5 fraction typically contains olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene, and diolefinic hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 3-methyl-1,2-butadiene. Commercially available C5 resins can be used.

[0095] The C5-C9 resin refers to a C5-C9 synthetic petroleum resin, and examples of the C5-C9 resin include petroleum-derived C5-C 11 Examples of such solid polymers include those obtained by polymerizing the fraction using a Friedel-Crafts catalyst such as AlCl3 or BF3, and more specifically, copolymers containing styrene, vinyltoluene, α-methylstyrene, indene, etc. as the main component. As the C5-C9 resin, a resin with a low content of C9 or higher components is preferred from the viewpoint of compatibility with the rubber component. Here, "low content of C9 or higher components" means that the content of C9 or higher components in the total amount of resin is less than 50 mass%, preferably 40 mass% or less. Commercially available C5-C9 resins can be used.

[0096] The C9 resin refers to a C9 synthetic petroleum resin, for example, a solid polymer obtained by polymerizing a C9 fraction using a Friedel-Crafts catalyst such as AlCl3 or BF3. Examples of C9 resins include copolymers containing indene, α-methylstyrene, vinyltoluene, and the like as main components.

[0097] The terpene resin is a solid resin obtained by blending turpentine, which is obtained simultaneously with the extraction of rosin from pine trees, or a polymerization component separated from the blend, and polymerizing the blend using a Friedel-Crafts catalyst. Examples of such resins include β-pinene resin and α-pinene resin. Furthermore, a representative example of a terpene-aromatic compound resin is terpene-phenol resin. This terpene-phenol resin can be obtained by reacting terpenes with various phenols using a Friedel-Crafts catalyst or by further condensing the terpene with formalin. There are no particular limitations on the terpenes used as raw materials; monoterpene hydrocarbons such as α-pinene and limonene are preferred, with those containing α-pinene being more preferred, and α-pinene being particularly preferred. Styrene or the like may also be included in the skeleton.

[0098] The dicyclopentadiene-based resin refers to a resin obtained by polymerizing dicyclopentadiene using a Friedel-Crafts catalyst such as AlCl3 or BF3.

[0099] Furthermore, the resin used as a raw material for the hydrogenated resin may contain, for example, a resin obtained by copolymerizing a C5 fraction with dicyclopentadiene (DCPD) (C5-DCPD resin). Here, if the dicyclopentadiene-derived component is 50% by mass or more of the total resin, the C5-DCPD-based resin is considered to be included in the dicyclopentadiene-based resin. If the dicyclopentadiene-derived component is less than 50% by mass of the total resin, the C5-DCPD-based resin is considered to be included in the C5-based resin. The same applies to cases where a small amount of a third component is also contained.

[0100] From the viewpoint of increasing the compatibility between the rubber component and the hydrogenated resin and further improving the wet performance of a tire using the rubber composition, the hydrogenated resin is preferably at least one selected from the group consisting of hydrogenated C5 resins, hydrogenated C5-C9 resins, hydrogenated dicyclopentadiene resins (hydrogenated DCPD resins), and hydrogenated terpene resins, more preferably at least one selected from the group consisting of hydrogenated C5 resins and hydrogenated C5-C9 resins, and even more preferably a hydrogenated C5 resin. Furthermore, the hydrogenated resin is preferably a resin having a hydrogenated DCPD structure or a hydrogenated cyclic structure in at least one monomer.

[0101] --Other resins-- The rubber composition may further contain a resin other than the hydrogenated resin. When the rubber composition further contains a resin other than the hydrogenated resin, from the viewpoint of optimizing the softening point and molecular weight of the entire resin, the content of the hydrogenated resin relative to the combined amount of the hydrogenated resin and the resin other than the hydrogenated resin (total amount of resin) is preferably 40% by mass or more, more preferably 50% by mass or more, more preferably 55% by mass or more, even more preferably 60% by mass or more, and may even be 100% by mass (i.e., all of the resin is the hydrogenated resin). Furthermore, from the viewpoint of further improving the wet performance of the tire, the resin other than the hydrogenated resin is preferably at least one selected from C5 resins, C9 resins, C5-C9 resins, terpene resins, terpene-aromatic compound resins, rosin resins, dicyclopentadiene resins, and alkylphenol resins, and among these, resins selected from C9 resins or C5-C9 resins are particularly preferred.

[0102] (Silane coupling agent) The rubber composition of the present invention preferably further contains a silane coupling agent represented by the following general formula (1). [ka]

[0103] By incorporating the silane coupling agent represented by the general formula (1) into the rubber composition, the dispersibility of fillers such as silica can be significantly improved due to the synergistic effect with the high Tg modified SBR and low Tg modified SBR described above. As a result, the hysteresis loss (tan δ) of the rubber composition in the temperature range during normal driving is further reduced, and the balance between the wet performance and low rolling resistance of a tire using the rubber composition is further improved.

[0104] In the above general formula (1), R 1 , R 2 and R 3 are independently -OC j H 2j+1 , -(OC k H 2k -) a -OC m H 2m+1 or -C n H 2n+1 wherein j, m, and n each independently represent an integer of 0 to 12, and k and a each independently represent an integer of 1 to 12. In addition, in the above formula (1), R 4 is a linear, branched, or cyclic, saturated or unsaturated alkylene group, cycloalkylene group, cycloalkylalkylene group, cycloalkenylalkylene group, alkenylene group, cycloalkenylene group, cycloalkylalkenylene group, cycloalkenylalkenylene group, arylene group, or aralkylene group having 1 to 12 carbon atoms. In addition, in the above formula (1), 1 , R 2 and R 3 At least one of the j H 2j+1 It is preferable that:

[0105] Examples of the compound represented by the formula (1) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, (mercaptomethyl)dimethylethoxysilane, (mercaptomethyl)dimethylethoxysilane, mercaptomethyltrimethoxysilane, and ethoxy(3-mercaptopropyl)bis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silane {manufactured by Evonik Degussa, trade name "Si363" and [C 13 H 27 O(CH2CH2O)5]2(CH3CH2O)Si(CH2)3SH}, etc. Among these, ethoxy(3-mercaptopropyl)bis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silane is preferred from the viewpoint of achieving excellent low loss properties. These silane coupling agents may be used alone or in combination of two or more.

[0106] The content of the silane coupling agent is not particularly limited, but can be 1 to 20 parts by mass per 100 parts by mass of the silica (or, if no silica is included, per 100 parts by mass of the total amount of filler). When the content of the silane coupling agent is 1 part by mass or more per 100 parts by mass of the silica, the effect of the coupling agent can be fully exerted, and when the content is 20 parts by mass or less per 100 parts by mass of the silica, gelation of the rubber component can be prevented. From the same viewpoint, the content of the silane coupling agent is preferably in the range of 5 to 15 parts by mass per 100 parts by mass of the silica.

[0107] (Guanidines) The rubber composition of the present invention preferably further contains a guanidine. Examples of the guanidine include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatechol borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine. Among these, diphenylguanidine (DPG) is preferred. These guanidines may be used alone or in combination of two or more. As will be described later, by adding guanidines in the first kneading step in which the rubber component, the filler, and the resin are kneaded, the viscosity (unvulcanized viscosity) of the rubber composition is reduced, thereby improving workability during kneading. The content of the guanidines in the rubber composition is preferably in the range of 0.1 to 5 parts by mass, more preferably in the range of 1 to 3 parts by mass, per 100 parts by mass of the rubber component.

[0108] (vulcanizing agent) The rubber composition of the present invention preferably further contains a vulcanizing agent, such as sulfur. The content of the vulcanizing agent is preferably in the range of 0.1 to 10 parts by mass, more preferably 1 to 4 parts by mass, in terms of sulfur content, per 100 parts by mass of the rubber component.

[0109] (Other ingredients) The rubber composition may contain the above-mentioned rubber components, fillers, resins, silane coupling agents, guanidines, and vulcanizing agents, as well as various components commonly used in the rubber industry, such as softeners, processing aids, stearic acid, antioxidants, zinc oxide, and vulcanization accelerators, as needed, selected appropriately within the scope of the present invention.

[0110] (Method of manufacturing rubber composition) The method for producing the rubber composition is not particularly limited, but the rubber composition can be produced, for example, by blending various components appropriately selected as necessary with the above-mentioned rubber component, filler, and resin, followed by kneading, heating, extruding, etc. The obtained rubber composition can be vulcanized to produce a vulcanized rubber.

[0111] The conditions for the kneading are not particularly limited, and various conditions such as the input volume of the kneading device, the rotation speed of the rotor, the ram pressure, the kneading temperature, the kneading time, the type of kneading device, etc. can be appropriately selected depending on the purpose. Examples of the kneading device include a Banbury mixer, an intermix, a kneader, a roll, etc. that are usually used for kneading rubber compositions.

[0112] The conditions for the heat-in are not particularly limited, and various conditions such as the heat-in temperature, heat-in time, and heat-in device can be appropriately selected depending on the purpose. Examples of the heat-in device include a heat-in roll mill typically used for heat-in of rubber compositions.

[0113] The extrusion conditions are not particularly limited, and various conditions such as extrusion time, extrusion speed, extrusion device, and extrusion temperature can be appropriately selected depending on the purpose. Examples of the extrusion device include an extruder typically used for extruding rubber compositions. The extrusion temperature can be appropriately determined.

[0114] The vulcanization apparatus, method, conditions, etc. are not particularly limited and can be appropriately selected depending on the purpose. Examples of vulcanization apparatus include a molding vulcanizer using a mold used for vulcanizing rubber compositions. The vulcanization temperature is, for example, about 100 to 190°C.

[0115] When the rubber composition of the present invention contains a guanidine and a vulcanizing agent, the rubber composition is preferably produced through (1) a first kneading step of kneading the rubber component, the filler, the resin, and the guanidine, and (2) a second kneading step of kneading the mixture obtained in the first kneading step with the vulcanizing agent. The method for producing the rubber composition of the present invention is a method for producing such a rubber composition, characterized by including a first kneading step of kneading the rubber component, the filler, the resin, and the guanidine, and a second kneading step of kneading the mixture obtained in the first kneading step with the vulcanizing agent. By kneading the guanidine in addition to the rubber component, filler, and resin in the first kneading step, the viscosity (unvulcanized viscosity) of the rubber composition is reduced, improving workability during kneading.

[0116] Examples of the guanidines include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatechol borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, etc. These guanidines may be used alone or in combination of two or more.

[0117] Among the guanidines, 1,3-diphenylguanidine is preferred. By kneading 1,3-diphenylguanidine (DPG) in addition to the rubber component, filler, and resin in the first kneading step, the viscosity (unvulcanized viscosity) of the rubber composition is reduced, further improving workability during kneading.

[0118] The amount of the guanidine compounded in the first kneading step is preferably in the range of 0.1 to 5 parts by mass, more preferably in the range of 1 to 3 parts by mass, per 100 parts by mass of the rubber component. In addition, since the guanidines have an action as a vulcanization accelerator, for example, when the finally obtained rubber composition contains a vulcanization accelerator and the guanidines are blended in the first kneading step, the amount of the vulcanization accelerator blended in the subsequent kneading step (e.g., the second kneading step, etc.) can be reduced.

[0119] (Uses of rubber compositions) The rubber composition of the present embodiment can be used for various rubber products including tires, and is particularly preferred as a rubber composition for tires.

[0120] <Tires> The tire of the present invention is characterized by having a tread rubber made of the above rubber composition. Such a tire of the present invention has excellent wet performance and low rolling resistance. The tire of the present invention is preferably a pneumatic tire.

[0121] The tire may be obtained by molding an unvulcanized rubber composition and then vulcanizing it, depending on the type of tire and the components to be applied, or by first obtaining a semi-vulcanized rubber from the unvulcanized rubber composition through a pre-vulcanization step or the like, molding the semi-vulcanized rubber using the semi-vulcanized rubber, and then further vulcanizing the tire. When the tire is a pneumatic tire, the gas to be filled into the pneumatic tire may be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium. [Example]

[0122] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0123] <Analysis method for modified SBR> The glass transition temperature (Tg), bound styrene content and microstructure of the butadiene portion of the modified SBR are measured by the following methods.

[0124] (1) Glass transition temperature (Tg) Using the synthesized modified SBR as a sample, a DSC curve was recorded using a TA Instruments DSC250 while increasing the temperature from -100°C at a rate of 20°C / min under a helium flow of 50 mL / min, and the peak top (inflection point) of the DSC differential curve was taken as the glass transition temperature.

[0125] (2) Bound styrene content Using the synthesized modified SBR as a sample, 100 mg of the sample was diluted to 100 mL with chloroform and dissolved to prepare a measurement sample. The amount of bound styrene (mass%) relative to 100 mass% of the sample was measured based on the amount of absorption of ultraviolet light by the phenyl group of styrene (near 254 nm). The measurement device used was a Shimadzu UV-2450 spectrophotometer.

[0126] (3) Microstructure The microstructure of the butadiene part of the synthesized modified SBR is 1 H-NMR spectrum (1,2-vinyl bond content) and 13 It is determined from the integral ratio of the C-NMR spectrum (ratio of the cis-1,4 bond content to the trans-1,4 bond content).

[0127] <Analysis method for hydrogenated resin> The softening point and weight average molecular weight of the hydrogenated resin are measured by the following method.

[0128] (4) Softening point The softening point of the hydrogenated resin is measured in accordance with JIS-K2207-1996 (ring and ball method).

[0129] (5) Weight average molecular weight The average molecular weight of the hydrogenated resin is measured by gel permeation chromatography (GPC) under the following conditions, and the weight average molecular weight in terms of polystyrene is calculated. Column temperature: 40℃ ·Injection volume: 50μL Carrier and flow rate: Tetrahydrofuran 0.6 mL / min Sample preparation: Dissolve approximately 2.5 g of hydrogenated resin in 10 mL of tetrahydrofuran.

[0130] <Preparation of Rubber Composition> The rubber compositions of the Examples and Comparative Examples were prepared using a conventional Banbury mixer, with the formulation shown in Table 1, by carrying out mixing in the first kneading step and then the second kneading step. After the first kneading step was completed, the mixture was temporarily removed from the Banbury mixer, and then the mixture was again introduced into the Banbury mixer to carry out the second kneading step. The maximum temperature of the mixture in the first kneading step was 145°C, and the maximum temperature of the rubber composition in the second kneading step was 105°C.

[0131] <Evaluation of Rubber Composition> The obtained rubber compositions were evaluated for wet performance, rolling resistance, reinforcement, and workability by the following methods.

[0132] (6) Wet performance The loss tangent (tanδ) of the vulcanized rubber obtained by vulcanizing each rubber composition was measured using a viscoelasticity measuring device under conditions of a temperature of -5°C, a dynamic strain of 1% after applying an initial strain, and a frequency of 15 Hz, and the loss tangent was expressed as an index, with the tanδ of Comparative Example 1 being set at 100. A larger index value indicates a larger tanδ and better wet performance when applied to a tire.

[0133] (7) Rolling resistance performance The loss tangent (tanδ) of the vulcanized rubber obtained by vulcanizing each rubber composition was measured using a viscoelasticity measuring device under conditions of a temperature of 50°C, a dynamic strain of 1% after applying an initial strain, and a frequency of 15 Hz, and the loss tangent was expressed as an index, with the reciprocal of tanδ of Comparative Example 1 set to 100. A larger index value indicates a smaller tanδ, which means a smaller rolling resistance when applied to a tire.

[0134] (8) Reinforcement For the vulcanized rubber obtained by vulcanizing each rubber composition, EB (elongation at break (%)) and TB (tensile strength (MPa)) were measured by performing a tensile test at 100°C in accordance with JIS K6251, and TF (toughness: EB x TB) was calculated and expressed as an index, with the TF (toughness) of Comparative Example 1 being set at 100. A larger index value indicates higher TF (toughness) and better reinforcement.

[0135] (9) Workability Mooney viscosity ML according to JIS K 6300 1+4 The viscosity (130°C) was measured and expressed as an index, with the reciprocal of the Mooney viscosity of Comparative Example 1 being set at 100. A larger index value indicates a lower Mooney viscosity and better workability.

[0136] [Table 1]

[0137] *1 NR: Natural rubber, RSS#3 *2 Low Tg modified SBR: Low Tg alkoxysilane modified styrene-butadiene rubber synthesized by the following method, Tg = -65°C, bound styrene content = 10% by mass *3 High-Tg modified SBR: High-Tg alkoxysilane-modified styrene-butadiene rubber synthesized using the following method, Tg = -25°C, bound styrene content = 41% by mass *4 Silica: Tosoh Silica Industries Co., Ltd., product name "Nipsil AQ" *5 Aluminum hydroxide: Manufactured by Showa Denko K.K., product name "Hijilite (registered trademark)" *6 Carbon black: Asahi Carbon Co., Ltd., product name "#80" *7 Wax: Product name "Suntite A" manufactured by Seiko Chemical Co., Ltd. *8 Anti-aging agent: Sumitomo Chemical Co., Ltd., product name "Antigen 6C" *9 Hydrogenated C5 resin: Manufactured by Eastman, product name "Registered Trademark Impera E1780", softening point = 130℃, weight average molecular weight (Mw) = 909g / mol *10 Silane coupling agent A: bis(3-triethoxysilylpropyl) disulfide, (average sulfur chain length: 2.35), manufactured by Evonik, trade name "Si75 (registered trademark)" *11 Silane coupling agent B: ethoxy(3-mercaptopropyl)bis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silane, manufactured by Evonik Degussa, trade name "Si363 (registered trademark)" *12 DPG: 1,3-diphenylguanidine, manufactured by Sumitomo Chemical Co., Ltd., trade name "Soccinol DG" *13 Vulcanization system: Total amount of vulcanization accelerator DPG (1,3-diphenylguanidine), vulcanization accelerator DM (di-2-benzothiazolyl disulfide), vulcanization accelerator NS (N-tert-butyl-2-benzothiazolylsulfenamide), vulcanization accelerator CZ (N-cyclohexyl-2-benzothiazolylsulfenamide), and sulfur (vulcanization agent). *14 Retarder: Toray Industries, Inc., product name "Retarder CTP"

[0138] <Synthesis method of low Tg modified SBR(*2)> A cyclohexane solution of 1,3-butadiene and a cyclohexane solution of styrene were added to a dried, nitrogen-purged 800 mL pressure-resistant glass vessel so that the total weight of the mixture was 67.5 g of 1,3-butadiene and 7.5 g of styrene. 0.09 mmol of 2,2-ditetrahydrofurylpropane and 0.7 mmol of n-butyllithium were then added, and polymerization was carried out at 50 °C for 1.5 hours. At this point, the polymerization conversion rate of the polymerization reaction system reached nearly 100%, and 0.63 mmol of N,N-bis(trimethylsilyl)-3-[diethoxy(methyl)silyl]propylamine was added as a modifier, and the modification reaction was carried out at 50 °C for 30 minutes. The reaction was then terminated by adding 2 mL of a 5% by weight solution of 2,6-di-t-butyl-p-cresol (BHT) in isopropanol. The mixture was then dried in the usual manner to obtain a modified SBR with one end modified. The obtained one-end-modified SBR had a glass transition temperature (Tg) of −65° C. and a bound styrene content of 10% by mass.

[0139] <Method for synthesizing high Tg modified SBR(*3)> (i) Preparation of modified initiator Two vacuum-dried 4 L stainless steel pressure vessels were prepared. 944 g of cyclohexane, 161 g of the compound represented by the following structural formula (3-1), and 86 g of tetramethylethylenediamine were charged into the first pressure vessel to produce a first reaction solution. Simultaneously, 318 g of 20% by mass liquid n-butyllithium and 874 g of cyclohexane were charged into the second pressure vessel to produce a second reaction solution. At this time, the molar ratio of the compound represented by the following structural formula (3-1), n-butyllithium, and tetramethylethylenediamine was 1:1:1. While maintaining the pressure of each pressure vessel at 7 bar, the first reaction solution was injected into the first continuous channel at a rate of 1.0 g / min using a mass flow meter, and the second reaction solution was injected into the second continuous channel at a rate of 1.0 g / min. During this time, the temperature of the continuous reactor is maintained at -10°C, the internal pressure is maintained at 3 bar using a back pressure regulator, and the residence time in the reactor is adjusted to within 10 minutes. The reaction is terminated to obtain a modified initiator. [ka]

[0140] (ii) Polymerization process Into the first reactor of a series of three reactors connected in series, 7.99 kg / h of a styrene solution in n-hexane (60% by weight), 10.55 kg / h of a 1,3-butadiene solution in n-hexane (60% by weight), 47.66 kg / h of n-hexane, 10 g / h of a 1,2-butadiene solution in n-hexane (2.0% by weight), 10.0 g / h of a 10% by weight solution of 2,2-di(2-tetrahydrofuryl)propane in n-hexane as a polar additive, and 292.50 g / h of the modified initiator prepared in the above Preparation Example were injected. The temperature of the first reactor was maintained at 50°C, and when the polymerization conversion rate reached 43%, the polymer was transferred from the first reactor to the second reactor through the transfer pipe. Subsequently, a 1,3-butadiene solution in which 1,3-butadiene is dissolved in n-hexane at a concentration of 60% by mass is injected into the second reactor at a rate of 0.95 kg / h. At this time, the temperature of the second reactor is maintained at 65°C, and when the polymerization conversion rate reaches 95% or more, the polymer is transferred from the second reactor to the third reactor through the transfer pipe. The polymer is transferred from the second reactor to the third reactor, and a solution containing a compound represented by the following structural formula (2-1) dissolved as a modifier is added to the third reactor (modifier:active Li=1:1 mol). The temperature of the third reactor is maintained at 65°C. [ka] Then, a 30% by mass solution of IR1520 (BASF) as an antioxidant is added to the polymer solution discharged from the third reactor at a rate of 170 g / h and stirred. The resulting polymer is added to steam-heated hot water and stirred to remove the solvent, yielding a modified SBR with both ends modified. The obtained both-end-modified SBR had a glass transition temperature (Tg) of -25°C, a bound styrene content of 41 mass%, a vinyl bond content in the butadiene portion of 45%, a weight average molecular weight (Mw) of 440,000, and a molecular weight distribution (Mw / Mn) of 1.6.

[0141] It can be seen from Table 1 that the rubber compositions of the examples according to the present invention are able to achieve both wet performance and low rolling resistance. In particular, (1) a comparison between Comparative Examples 1 and 2 and Examples 1 and 2, (2) a comparison between Comparative Example 3 and Example 3, and (3) a comparison between Comparative Example 4 and Example 4, which differ only in the mass ratio of the high-Tg modified SBR to the low-Tg modified SBR, reveals that by increasing the mass ratio of the high-Tg modified SBR to the low-Tg modified SBR to more than 1, it is possible to significantly improve wet performance while maintaining low rolling resistance. [Industrial Applicability]

[0142] The rubber composition of the present invention can be used for various rubber products, including tires.

Claims

1. The rubber composition includes a rubber component, a filler, and a resin, the rubber component comprises natural rubber, a high Tg modified styrene-butadiene rubber, and a low Tg modified styrene-butadiene rubber having a glass transition temperature (Tg) lower than that of the high Tg modified styrene-butadiene rubber; The high Tg modified styrene-butadiene rubber has one end represented by the following general formula (2): 【Chemical 1】 [wherein R 5 to R 12 are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms; L 1 and L 2 are each independently a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms; and n is an integer of 2 to 4.], and the other end is modified with a modifying agent containing a compound represented by the following general formula (3): 【Chemistry 2】 [wherein R 13 to R 15 are each independently hydrogen; an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms, a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; or a heterocyclic group having 3 to 30 carbon atoms; R 16 is a single bond; a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms; a substituted or unsubstituted cycloalkylene group having 5 to 20 carbon atoms; or a substituted or unsubstituted arylene group having 5 to 20 carbon atoms, wherein the substituent is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms; R 17 represents an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; a heterocyclic group having 3 to 30 carbon atoms; or a group represented by the following general formula (3a): 【Chemistry 3】 (In the formula, R 17a1 is an alkylene group having 1 to 20 carbon atoms which is substituted or unsubstituted; a cycloalkylene group having 5 to 20 carbon atoms which is substituted or unsubstituted; or an arylene group having 6 to 20 carbon atoms which is substituted or unsubstituted, wherein the substituent is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms; R 17a2 and R 17a3 are each independently an alkylene group having 1 to 20 carbon atoms which is substituted or unsubstituted with an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms; and R 17a4 represents hydrogen, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 to 30 carbon atoms, a heteroalkyl group having 1 to 30 carbon atoms, a heteroalkenyl group having 2 to 30 carbon atoms, a heteroalkynyl group having 2 to 30 carbon atoms, a cycloalkyl group having 5 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or a heterocyclic group having 3 to 30 carbon atoms, and X represents an N, O, or S atom, provided that when X is O or S, R 17a4 does not exist.) or the following general formula (3b): 【Chemistry 4】 (wherein R 17b1 is an alkylene group having 1 to 20 carbon atoms which is substituted or unsubstituted; a cycloalkylene group having 5 to 20 carbon atoms which is substituted or unsubstituted; or an arylene group having 6 to 20 carbon atoms which is substituted or unsubstituted, wherein the substituent is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms; and R 17b2 and R 17b3 are each independently an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; or a heterocyclic group having 3 to 30 carbon atoms), m is an integer of 1 to 5, at least one of R 17 is a functional group represented by the above general formula (3a) or (3b), and when m is an integer of 2 to 5, multiple R 17 may be the same or different from each other. The low Tg modified styrene-butadiene rubber has one end represented by the following general formula (5): 【Chemistry 5】 [wherein n1+n2+n3+n4=4 (n2 is an integer of 1 to 4, and n1, n3, and n4 are integers of 0 to 3), A 1 represents at least one functional group selected from a saturated cyclic tertiary amine compound residue, an unsaturated cyclic tertiary amine compound residue, a ketimine residue, a nitrile group, a (thio)isocyanate group, an isocyanuric acid trihydrocarbyl ester group, a nitrile group, a pyridine group, a (thio)ketone group, an amide group, and a primary or secondary amino group having a hydrolyzable group; when n4 is 2 or greater, A 1 may be the same or different, and A 1 may represent a divalent group that bonds with Si to form a cyclic structure; R 21 represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when n1 is 2 or greater, may be the same or different; R 23 represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a halogen atom, and when n3 is 2 or greater, may be the same or different; R 22 is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, either of which may contain a nitrogen atom and / or a silicon atom; when n2 is 2 or greater, R 22 may be the same or different from each other, or may be joined together to form a ring; R 24 is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when n4 is 2 or greater, R 24 may be the same or different.], and the other end is not modified, The rubber composition is characterized in that the mass ratio (content of high Tg modified SBR / content of low Tg modified SBR) of the content of the high Tg modified styrene-butadiene rubber (high Tg modified SBR) to the content of the low Tg modified styrene-butadiene rubber (low Tg modified SBR) is greater than 1.

2. Furthermore, the following general formula (1): 【Chemistry 6】 [In the formula, R １ , R ２ and R ３ are each independently —O—C ｊ H ２ｊ＋１ , -(O-C ｋ H ２ｋ -) ａ -O-C ｍ H ２ｍ＋１ or -C ｎ H ２ｎ＋１ j, m, and n each independently represent a number from 0 to 12, k and a each independently represent a number from 1 to 12, and R ４ is a linear, branched, or cyclic, saturated or unsaturated alkylene group, cycloalkylene group, cycloalkyl alkylene group, cycloalkenyl alkylene group, alkenylene group, cycloalkenylene group, cycloalkyl alkenylene group, cycloalkenyl alkenylene group, arylene group, or aralkylene group, having 1 to 12 carbon atoms.

3. The rubber composition according to claim 1 or 2, further comprising a guanidine and a vulcanizing agent.

4. a first kneading step of kneading the rubber component, the filler, the resin, and the guanidines; a second kneading step of kneading the kneaded product obtained in the first kneading step with the vulcanizing agent; The method for producing a rubber composition according to claim 3, comprising:

5. The rubber composition according to claim 3, wherein the guanidine is 1,3-diphenylguanidine (DPG).

6. The rubber composition according to any one of claims 1 to 3 and 5, wherein the resin contains a hydrogenated resin having a softening point higher than 110°C and a weight average molecular weight in terms of polystyrene of 200 to 1600 g / mol.

7. The hydrogenated resin is hydrogenated C ５ based resin, hydrogenated C ５ -C ９ The rubber composition according to claim 6, wherein the rubber composition is at least one selected from the group consisting of a dicyclopentadiene-based resin and a hydrogenated dicyclopentadiene-based resin.

8. The rubber composition according to any one of claims 1 to 3 and 5 to 7, wherein the amount of the resin is 2 to 15 parts by mass per 100 parts by mass of the rubber component.

9. A tire comprising a tread rubber made of the rubber composition according to any one of claims 1 to 3 and 5 to 8.

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