Rubber composition for tire and tire

Abstract

Provided are a rubber composition for a tire that exhibits excellent wet grip performance, rolling resistance characteristics, and thermal sagging resistance, and a tire manufactured by using the rubber composition for a tire. A rubber composition for a tire according to the present invention contains: a conjugated diene rubber containing an aromatic vinyl-conjugated diene copolymer rubber; silica; a silane coupling agent; and a resin. The aromatic vinyl-conjugated diene copolymer rubber contains a specific conjugated diene rubber. The resin has an aromatic hydrocarbon-derived proton ratio of 20% or more as determined by NMR and a parameter S of 300 or more. The content of the specific conjugated diene rubber relative to the content of conjugated diene rubber is 30 mass% or more, and the content of the resin relative to the content of the aromatic vinyl-conjugated diene copolymer rubber is 1-100 mass%.

Description

Rubber composition for tires and tires

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

[0002] BACKGROUND ART Conventionally, rubber compositions for tires containing petroleum resins have been known from the viewpoint of controlling properties such as viscoelasticity (for example, Patent Document 1).

[0003] JP 2024-002387 A

[0004] Recently, further improvements in wet grip performance, rolling resistance, and heat sagging resistance have been required from the viewpoints of safety, environmental issues, etc. In this context, the present inventors have studied the rubber composition for tires described in Patent Document 1, and have found that the performance of the rubber composition when used in tires may not always be sufficient.

[0005] In view of the above circumstances, the present invention aims to provide a rubber composition for tires that exhibits excellent wet grip performance, rolling resistance characteristics, and heat sagging resistance when made into a tire, and a tire manufactured using the rubber composition for tires.

[0006] As a result of intensive research into the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by blending a specific conjugated diene rubber in a specific ratio and blending a specific resin in a specific ratio, and have arrived at the present invention. That is, the present inventors have found that the above-mentioned problems can be solved by the following configuration.

[0007] [1] A conjugated diene rubber containing an aromatic vinyl-conjugated diene copolymer rubber, silica, a silane coupling agent, and a resin, wherein the aromatic vinyl-conjugated diene copolymer rubber contains a specific conjugated diene rubber, and the specific conjugated diene rubber is a conjugated diene rubber produced by a method for producing a conjugated diene rubber, the method comprising: a first step of polymerizing a monomer containing a conjugated diene compound and an aromatic vinyl compound in an inert solvent using a polymerization initiator to obtain a conjugated diene polymer chain having an active end; and a second step of adding a polyorganosiloxane represented by general formula (1) described below to the conjugated diene polymer chain having an active end in a proportion of 1 mol or more calculated as the number of repeating units of the siloxane structure (—Si—O—) in the polyorganosiloxane per 1 mol of the polymerization initiator used in the first step, and reacting the polyorganosiloxane with the conjugated diene polymer chain. The rubber composition for tires is a resin in which the ratio of aromatic hydrocarbon-derived protons determined by an NMR method is 20% or more and the parameter S described below is 300 or more, the content of the specific conjugated diene rubber relative to the content of the conjugated diene rubber is 30% by mass or more, and the content of the resin relative to the content of the aromatic vinyl-conjugated diene copolymer rubber is 1 to 100% by mass. １ ~R ８ represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, which may be the same or different, X １ and X ４ represents any group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an epoxy group-containing group having 4 to 12 carbon atoms, which may be the same or different from each other; X ２ is an alkoxy group having 1 to 5 carbon atoms or a group containing an epoxy group and having 4 to 12 carbon atoms, and a plurality of X ２ may be the same or different, and X ３ is a group containing 2 to 20 repeating alkylene glycol units, and X ３When there are a plurality of m, they may be the same or different, m is an integer of 3 to 200, n is an integer of 0 to 200, k is an integer of 0 to 200, and m+n+k is 3 or more. [2] The cetyltrimethylammonium bromide adsorption specific surface area of ​​the silica is 140 m ２ [3] The rubber composition for a tire according to [1] or [2], further comprising an alkyltriethoxysilane represented by the general formula (I) described later, in which the content of the alkyltriethoxysilane is 2.0 to 15.0 mass % relative to the content of the silica. １ represents an alkyl group having 7 to 20 carbon atoms, and Et represents an ethyl group. [4] A tire manufactured using the rubber composition for a tire according to any one of [1] to [3].

[0008] As will be described below, according to the present invention, it is possible to provide a rubber composition for a tire that exhibits excellent wet grip performance, rolling resistance characteristics, and heat sagging resistance when made into a tire, and a tire manufactured using the rubber composition for a tire.

[0009] 1 is a total ion chromatogram obtained by pyrolysis GC-MS of Resin A. FIG. 2 is a partial cross-sectional schematic view showing an example of an embodiment of a tire of the present invention.

[0010] The rubber composition for tires of the present invention will be described below. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. Each component may be used alone or in combination of two or more. When two or more components are used in combination, the content of the components refers to the total content unless otherwise specified. Regarding the rubber composition for tires, the wet grip performance, rolling resistance, and heat sagging performance of the tire when made into a tire are also referred to simply as "wet grip performance," "rolling resistance," and "heat sagging performance," respectively.

[0011] [I] Rubber Composition for Tire The rubber composition for tire of the present invention (hereinafter also referred to as "the composition of the present invention") comprises a conjugated diene rubber containing an aromatic vinyl-conjugated diene copolymer rubber, silica, a silane coupling agent, and a resin, wherein the aromatic vinyl-conjugated diene copolymer rubber contains a specific conjugated diene rubber, and the specific conjugated diene rubber is a conjugated diene rubber produced by a method for producing a conjugated diene rubber, the method comprising: a first step of polymerizing a monomer containing a conjugated diene compound and an aromatic vinyl compound in an inert solvent using a polymerization initiator to obtain a conjugated diene polymer chain having an active end; and a second step of adding a polyorganosiloxane represented by general formula (1) described below to the conjugated diene polymer chain having an active end in a proportion of 1 mol or more calculated as the number of repeating units of the siloxane structure (-Si-O-) in the polyorganosiloxane per 1 mol of the polymerization initiator used in the first step, and reacting the polyorganosiloxane with the conjugated diene polymer chain. The rubber composition for tires is one in which the resin has a ratio of aromatic hydrocarbon-derived protons determined by an NMR method of 20% or more and a parameter S (described later) of 300 or more, the content of the specific conjugated diene rubber relative to the content of the conjugated diene rubber is 30% by mass or more, and the content of the resin relative to the content of the aromatic vinyl-conjugated diene copolymer rubber is 1 to 100% by mass.

[0012] The composition of the present invention is thought to be able to solve the above-mentioned problems because of its configuration. The reason for this is not clear, but is presumed to be roughly as follows. As described above, the composition of the present invention contains a predetermined amount of a resin (hereinafter also referred to as a "specific resin") having an aromatic hydrocarbon-derived proton ratio of 20% or more as determined by NMR (nuclear magnetic resonance) and a parameter S (described below) of 300 or more relative to the aromatic vinyl-conjugated diene copolymer rubber. The specific resin has a structure similar to that of the aromatic vinyl-conjugated diene copolymer rubber because the aromatic hydrocarbon-derived proton ratio (hereinafter also referred to as an "aromatic proton ratio") is 20% or more. Furthermore, the specific resin has a parameter S (hereinafter also referred to as an "S value") (described below) of 300 or more. Here, the S value is a parameter relating to the retention coefficient of peaks (however, peaks with a retention coefficient of 6 or less) and area ratio in a total ion chromatogram (hereinafter also referred to as "TIC") of pyrolysis gas chromatography mass spectrometry (hereinafter also referred to as "pyrolysis GC-MS") using a packing material (structure shown below) similar in structure to SBR, and represents the retention of the monomers constituting the resin to the packing material. The specific resin has an S value equal to or greater than a specific value, and is therefore considered to have extremely high compatibility with aromatic vinyl-conjugated diene copolymer rubber.

[0013]

[0014] As a result, in the composition of the present invention, the conjugated diene rubber including the aromatic vinyl-conjugated diene copolymer rubber and the specific resin are compatible to an extremely high degree, which is thought to lead to excellent wet grip performance and rolling resistance characteristics.

[0015] As described above, the composition of the present invention contains a predetermined amount of specific conjugated diene rubber relative to the content of the conjugated diene rubber. The specific conjugated diene rubber has a structure based on a polyorganosiloxane represented by the general formula (1) described below, and is therefore similar to the structure of the filler used in the pyrolysis GC-MS described above. This increases the interaction between the specific conjugated diene rubber and the specific resin having an S value equal to or greater than a specific value, which is thought to suppress a decrease in rigidity at high temperatures and provide excellent heat sagging resistance.

[0016] Each component contained in the composition of the present invention will be described below.

[0017] [1] Conjugated diene rubber The conjugated diene rubber contained in the composition of the present invention includes an aromatic vinyl-conjugated diene copolymer rubber.

[0018] In the composition of the present invention, the aromatic vinyl-conjugated diene copolymer rubber preferably contains a specific conjugated diene rubber and further contains an aromatic vinyl-conjugated diene copolymer rubber other than the specific conjugated diene rubber (hereinafter also referred to as "other aromatic vinyl-conjugated diene copolymer rubber"). The content of the aromatic vinyl-conjugated diene copolymer rubber in the conjugated diene rubber is preferably 30 to 100% by mass, more preferably 35 to 100% by mass, and even more preferably 40 to 100% by mass, in terms of more excellent effects of the present invention.

[0019] [Specific Conjugated Diene Rubber] The specific conjugated diene rubber contained in the composition of the present invention is a conjugated diene rubber produced by a method for producing a conjugated diene rubber comprising the following steps 1 and 2: (1) Step 1: A first step of polymerizing a monomer containing a conjugated diene compound and an aromatic vinyl compound in an inert solvent using a polymerization initiator to obtain a conjugated diene polymer chain having an active end; (2) Step 2: A second step of adding a polyorganosiloxane represented by general formula (1) described below to the conjugated diene polymer chain having an active end in a ratio of 1 mol or more calculated as the number of repeating units of the siloxane structure (—Si—O—) in the polyorganosiloxane per 1 mol of the polymerization initiator used in Step 1, to cause a reaction.

[0020] First, the reason why the specific conjugated diene rubber is specified by the above-mentioned production method will be explained. As described above, in the second step, a conjugated diene polymer chain having an active terminal is reacted with a polyorganosiloxane represented by the general formula (1) described below. Here, as described below, the active terminal of the conjugated diene polymer chain may react with a silicon atom in the siloxane structure or with an alkoxy group or epoxy group in the side chain of the polyorganosiloxane. Therefore, since the reaction residue produced by the reaction of the conjugated diene polymer chain having an active terminal with the polyorganosiloxane can have various structures, analyzing the structure is technically impossible, or performing the work of identifying the structure requires significantly excessive economic expenditure and time. Therefore, there are so-called "impossible or impractical circumstances" when describing the specific conjugated diene rubber as "a conjugated diene rubber produced by a conjugated diene rubber production method comprising steps 1 and 2."

[0021] Each step will be described below.

[0022] [Step 1] Step 1 is a step of polymerizing monomers including a conjugated diene compound and an aromatic vinyl compound in an inert solvent using a polymerization initiator to obtain a conjugated diene polymer chain having an active terminal. Details and preferred embodiments of Step 1 are the same as those described in paragraphs 0020 to 0078 of Japanese Patent No. 6,879,263, and therefore will not be described here.

[0023] [Step 2] Step 2 is a step of adding a polyorganosiloxane represented by the following general formula (1) to the conjugated diene polymer chain having an active terminal obtained in Step 1, in a ratio of 1 mol or more calculated as the number of repeating units of the siloxane structure (—Si—O—) in the polyorganosiloxane per 1 mol of the polymerization initiator used in Step 1, to cause a reaction.

[0024]

[0025] In general formula (1), R １ ~R ８ represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, which may be the same or different.１ and X ４ is any group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an epoxy group-containing group having 4 to 12 carbon atoms, and these may be the same or different. ２ is an alkoxy group having 1 to 5 carbon atoms or a group having 4 to 12 carbon atoms containing an epoxy group, and ２ They may be the same or different from each other. ３ is a group containing 2 to 20 repeating alkylene glycol units, and X ３ When there are a plurality of m, they may be the same or different. m is an integer of 3 to 200, n is an integer of 0 to 200, k is an integer of 0 to 200, and m+n+k is 3 or more.

[0026] Details and preferred embodiments of the second step are the same as those described in paragraphs 0079 to 0101 of Japanese Patent No. 6879263, and therefore will not be described here.

[0027] In the second step, the active terminals of the conjugated diene polymer chain having active terminals obtained in the first step are reacted with polyorganosiloxane as a modifier, and the active terminals of the conjugated diene polymer chain react with silicon atoms in the siloxane structure. Alternatively, a part of the active terminals of the conjugated diene polymer chain may be bonded to an alkoxy group or epoxy group (X, which is essentially contained in the general formula (1)) in the side chain of the polyorganosiloxane. ２ In the second step, the siloxane reacts with the alkoxy group or epoxy group that forms a siloxane-modified structure in the conjugated diene polymer chain.

[0028] Specifically, the active end of the conjugated diene polymer chain reacts with the silicon atom in the siloxane structure, and a new bond is formed between the silicon atom in the siloxane structure and the active end of the conjugated diene polymer chain, and a modified structure by siloxane is introduced at the end of the conjugated diene polymer chain, and a reaction residue, such as -O, is formed between the oxygen atom in the siloxane structure and the metal atom that formed the active end of the conjugated diene polymer chain. － M ＋ (wherein M is an alkali metal atom, an alkaline earth metal atom, or a lanthanide metal atom) is thought to be formed.

[0029] Alternatively, the active end of the conjugated diene polymer chain reacts with the epoxy group on the side chain of the polyorganosiloxane, causing the ring-opening of the epoxy group, forming a new bond between the carbon atom at the ring-opened portion of the epoxy group and the active end of the conjugated diene polymer chain, and a siloxane structure is introduced at the end of the conjugated diene polymer chain, while at the same time forming a reaction residue between the oxygen atom in the epoxy group and the metal atom that formed the active end of the conjugated diene polymer chain, such as -O － M ＋ Alternatively, the active end of the conjugated diene polymer chain reacts with the alkoxy group on the side chain of the polyorganosiloxane, resulting in the elimination of the alkoxy group, and the conjugated diene polymer chain forms a new bond between the silicon atom in the siloxane structure and the active end of the conjugated diene polymer chain, thereby introducing a siloxane structure into the end of the conjugated diene polymer chain.

[0030] In particular, in the second step, the amount of polyorganosiloxane used is 1 mole or more, calculated as the number of repeating units of the siloxane structure (—Si—O—), per mole of polymerization initiator, so that a modified structure by siloxane can be introduced into almost all of the conjugated diene polymer chains having active ends obtained in the first step. Therefore, the alkyl metal group, i.e., —R － M ＋It is possible to make the state such that almost all of the -O as a reactive residue does not remain. － M ＋ However, in the present invention, a very small amount (for example, 5% by mass or less) of a conjugated diene polymer chain having an unmodified active end that has not been modified with siloxane may be included (that is, a very small amount of an alkyl metal group, i.e., -R － M ＋ The present invention does not exclude such cases.

[0031] In the second step, before the conjugated diene polymer chain having an active end is reacted with the polyorganosiloxane represented by general formula (1), a part of the active end of the conjugated diene polymer chain having an active end may be coupled or modified by adding a conventionally used coupling agent or modifying agent to the polymerization system, within a range that does not impair the effects of the present invention.

[0032] [Step 3] The specific conjugated diene rubber may be a conjugated diene rubber produced by carrying out Step 3 after Steps 1 and 2. Step 3 is a step of reacting a compound represented by the following general formula (2) with the conjugated diene polymer chain that has been reacted with the polyorganosiloxane obtained in Step 2.

[0033]

[0034] In general formula (2), R ９ is a hydrocarbyl group, A １ is a group capable of reacting with a reaction residue formed by the reaction of a conjugated diene polymer chain having an active terminal with a polyorganosiloxane, and A ２ is a group containing a nitrogen atom, p is an integer of 0 to 2, q is an integer of 1 to 3, r is an integer of 1 to 3, and p+q+r=4.

[0035] According to the present invention, in the second step, an alkyl metal group, i.e., —R － M ＋ In place of these, -O as a reaction residue by the reaction with the polyorganosiloxane represented by the general formula (1) is － M ＋ Therefore, in the third step, the compound represented by the general formula (2) has a group represented by —O as such a reactive residue. － M ＋ A group represented by (—O － M ＋ and (including those in which the group represented by the formula (I) is hydrolyzed and converted into a hydroxyl group).

[0036] That is, the compound represented by the general formula (2) is -R － M ＋ This can appropriately prevent the modified structure by the compound represented by general formula (2) from being directly introduced into the conjugated diene polymer chain by reacting with the group represented by general formula (3), and thus the modified structure by the compound represented by general formula (2) can be appropriately introduced into the conjugated diene polymer chain via the structure derived from the polyorganosiloxane represented by general formula (1).

[0037] However, the conjugated diene polymer chain reacted with polyorganosiloxane and used in the third step may be one that has undergone the second step described above, and in addition to the conjugated diene polymer chain into which a siloxane-modified structure has been introduced, a very small amount (for example, 5 mass % or less) of unmodified conjugated diene polymer chain having an active end to which no siloxane-modified structure has been introduced may remain (that is, a very small amount of alkyl metal group, i.e., -R － M ＋ may remain), and further, -O as a reaction residue formed as a result of the introduction of a modified structure by siloxane － M＋ may include those in which a part of the group has been hydrolyzed and converted into a hydroxyl group.

[0038] Details and preferred embodiments of the third step are the same as those described in paragraphs 0102 to 0119 of Japanese Patent No. 6879263, and therefore some of the description will be omitted.

[0039] As described above, the specific conjugated diene rubber is obtained by adding a polyorganosiloxane represented by general formula (1) as a modifier in a ratio of 1 mole or more, calculated as the number of repeating units of the siloxane structure (—Si—O—) in the polyorganosiloxane, to 1 mole of the polymerization initiator used in the first step, and then reacting the polyorganosiloxane. Furthermore, after the above-described step 2, the specific conjugated diene rubber may be obtained by reacting a compound represented by general formula (2) as a modifier in the third step. Therefore, the specific conjugated diene rubber may include those in which a siloxane-modified structure is introduced at the polymer chain end, and may also include those in which a modified structure by the compound represented by general formula (2) is introduced. In addition, the specific conjugated diene rubber may include those in which only a modified structure by the siloxane is introduced at the polymer chain end. Furthermore, within the scope that does not impair the effects of the present invention, for example, those in which only a modified structure by the compound represented by general formula (2) is introduced at the polymer chain end, or those in which neither modified structure is introduced, may also be included. In the present invention, the proportion of the polymer chain terminals into which the siloxane-modified structure and the compound represented by general formula (2) have been introduced may be 10% by mass or more, or may be 20% by mass or more, with no particular upper limit.

[0040] [Monomer unit content] The specific conjugated diene rubber preferably contains more than 0% by mass and not more than 30% by mass of aromatic vinyl monomer units, more preferably more than 0% by mass and not more than 20% by mass, and even more preferably more than 0% by mass and not more than 18% by mass, because the effects of the present invention are more excellent. Furthermore, the specific conjugated diene rubber preferably contains 70% by mass or more and less than 100% by mass of conjugated diene monomer units, more preferably 80% by mass or more and less than 100% by mass, and even more preferably 82% by mass or more and less than 100% by mass, because the effects of the present invention are more excellent.

[0041] [Vinyl Bond Content] The vinyl bond content in the conjugated diene monomer units in the specific conjugated diene rubber is preferably 8 to 65 mass%, more preferably 8 to 40 mass%, even more preferably 8 to 38 mass%, and particularly preferably 8 to 35 mass%, for reasons of better effects of the present invention.

[0042] [Coupling rate] The coupling rate of the specific conjugated diene rubber is not particularly limited, but is preferably 10% by mass or more, more preferably 20% by mass or more, particularly preferably 40% by mass or more, and is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less. The coupling rate is the mass fraction of the polymer molecules having a molecular weight of 1.8 times or more of the peak top molecular weight of the conjugated diene polymer chain having an active end before reacting with the polyorganosiloxane represented by general formula (1), the compound represented by general formula (2) used as needed, the coupling agent or other modifier, relative to the total amount of the finally obtained conjugated diene rubber. The molecular weight at this time is measured by gel permeation chromatography as a polystyrene-equivalent molecular weight.

[0043] [Molecular Weight] The weight average molecular weight (Mw) of the specific conjugated diene rubber, as measured by gel permeation chromatography in terms of polystyrene, is preferably 300,000 to 600,000, more preferably 320,000 to 600,000, even more preferably 350,000 to 550,000, and particularly preferably 400,000 to 500,000. By setting the weight average molecular weight of the specific conjugated diene rubber within the above range, it becomes easier to compound silica into the conjugated diene rubber, and the effects of the present invention become even more excellent.

[0044] The molecular weight distribution of the specific conjugated diene rubber, which is represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 1.1 to 3.0, more preferably 1.2 to 2.5, and even more preferably 1.2 to 2.2, for reasons of better effects of the present invention.

[0045] [Viscosity] Mooney viscosity (ML) of specific conjugated diene rubber １＋４ , 100°C) is preferably 20 to 100, more preferably 30 to 90, and even more preferably 35 to 80, because the effects of the present invention are more excellent. When the conjugated diene rubber is used as the oil-extended rubber, it is preferable that the Mooney viscosity of the oil-extended rubber be within the above range.

[0046] [Glass transition temperature] The glass transition temperature (Tg) of the specific conjugated diene rubber is preferably -100 to -20°C, more preferably -100 to -50°C, even more preferably -100 to -55°C, and particularly preferably -95 to -60°C. When the glass transition temperature is within the above range, the effects of the present invention are more excellent. Here, the glass transition temperature is a value measured using a differential scanning calorimeter (DSC) manufactured by DuPont in accordance with ASTM D3418-82 at a heating rate of 10°C / min.

[0047] [Content] The content of the specific conjugated diene rubber relative to the content of the conjugated diene rubber (hereinafter also referred to as "specific conjugated diene rubber / conjugated diene rubber") is 30% by mass or more, and from the viewpoint of more excellent effects of the present invention, it is preferably 40% by mass or more. The upper limit thereof is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, from the viewpoint of more excellent effects of the present invention.

[0048] [Other aromatic vinyl-conjugated diene copolymer rubbers] As described above, other aromatic vinyl-conjugated diene copolymer rubbers refer to aromatic vinyl-conjugated diene copolymer rubbers other than the specific conjugated diene rubber. Examples of aromatic vinyl-conjugated diene copolymer rubbers include styrene-butadiene rubber (SBR) and styrene-isoprene copolymer rubber, with SBR being preferred in terms of achieving better effects of the present invention.

[0049] The other aromatic vinyl-conjugated diene copolymer rubber may be an aromatic vinyl-conjugated diene copolymer rubber modified with a functional group that interacts with silica. The aromatic vinyl-conjugated diene copolymer rubber modified with a functional group that interacts with silica is preferably an SBR modified with a functional group that interacts with silica, in terms of achieving better effects of the present invention. Examples of functional groups that interact with silica include hydrocarbyloxysilyl groups, silanol groups, hydroxyl groups (excluding silanol groups), aldehyde groups, carboxyl groups, amino groups, imino groups, epoxy groups, amide groups, thiol groups, siloxane bonds, and ether bonds. In the diene rubber, the modifying group can be bonded to the terminal and / or side chain of the diene rubber directly or via a linking group. The linking group is not particularly limited.

[0050] [Content] The content of the other aromatic vinyl-conjugated diene copolymer rubber in the conjugated diene rubber is preferably 10% by mass or more, more preferably 20% by mass or more, from the viewpoint of achieving better effects of the present invention. The upper limit is preferably 70% by mass or less, more preferably 60% by mass or less, from the viewpoint of achieving better effects of the present invention when the blending amount of the specific conjugated diene rubber is more appropriate.

[0051] [Other Rubber Components] The conjugated diene rubber may contain rubber components other than the specific conjugated diene rubber and the other aromatic vinyl-conjugated diene copolymer rubber (hereinafter also referred to as "other rubber components"). Examples of such other rubber components include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), and chloroprene rubber (CR). Of these, NR and BR are preferred because they provide better effects of the present invention. The rubber component may be modified with an alkoxy group, an alkoxysilyl group, or the like.

[0052] [Average Tg] The glass transition temperature of the entire conjugated diene rubber (hereinafter also referred to as "average Tg") is not particularly limited, but for reasons of better effects of the present invention, it is preferably from -100°C to -20°C, and more preferably from -80°C to -20°C. Here, the average Tg of the conjugated diene rubber is the sum (weighted average value of glass transition temperatures) obtained by multiplying the glass transition temperature (Tg) of each conjugated diene rubber by the mass fraction of each rubber component.

[0053] [Molecular Weight] The weight average molecular weight (Mw) of the conjugated diene rubber is preferably 100,000 to 10,000,000, and more preferably 300,000 to 3,000,000, because the effects of the present invention are more excellent. Furthermore, the number average molecular weight (Mn) of the conjugated diene rubber contained in the composition of the present invention is preferably 50,000 to 5,000,000, and more preferably 150,000 to 1,500,000, because the effects of the present invention are more excellent. It is preferable that the Mw and / or Mn of at least one rubber component contained in the conjugated diene rubber fall within the above range, and it is more preferable that the Mw and / or Mn of all conjugated diene rubbers contained in the conjugated diene rubber fall within the above range. In this specification, Mw and Mn are values ​​calculated in terms of standard polystyrene obtained by gel permeation chromatography (GPC) measurement under the following conditions: Solvent: tetrahydrofuran Detector: RI detector

[0054] [2] Specific Resin The composition of the present invention contains a resin (specific resin) having a ratio of aromatic hydrocarbon-derived protons (aromatic proton ratio) of 20% or more as determined by an NMR method and a parameter S (S value) described below of 300 or more.

[0055] [Aromatic Proton Ratio] The aromatic proton ratio of the specific resin is 20% or more. The aromatic proton ratio is preferably 22% or more, more preferably 24% or more, even more preferably 26% or more, and particularly preferably 28% or more, because the effects of the present invention are more excellent. There is no particular upper limit to the ratio, but it is preferably 80% or less, more preferably 50% or less, because the effects of the present invention are more excellent.

[0056] The aromatic proton ratio is determined as follows: １ A H-NMR spectrum is measured. In the spectrum, the ratio of the area of ​​the peak of protons derived from aromatic hydrocarbons (aromatic rings) to the sum of the areas of the peaks of protons derived from the resin is calculated, and this is taken as the aromatic proton ratio. For example, when the resin is a styrene polymer (polystyrene), the aromatic proton ratio is the ratio of the peak area of ​​protons derived from benzene rings to the sum of the areas of the peaks of protons derived from polystyrene.

[0057] [S Value] The specific resin has a parameter S (S value) of 300 or more.

[0058]

[0059] Here, k ｎ represents the retention coefficient of the n-th peak from the smallest retention time in the total ion chromatogram obtained by pyrolysis gas chromatography mass spectrometry of a specific resin, and α represents the retention coefficient of the n-th peak from the smallest retention time in the total ion chromatogram obtained by pyrolysis gas chromatography mass spectrometry of a specific resin, and k ｎ represents the n of the peak having the maximum retention factor of ≦6.0, and A ｎ is k ｎ It represents the ratio (%) of the area of ​​the nth peak to the total area of ​​peaks that satisfy the condition ≦6.0.

[0060] The S value is preferably 330 or more, and more preferably 350 or more, because the effects of the present invention are more excellent. There is no particular upper limit to the S value, but the S value is preferably 500 or less, and more preferably 400 or less, because the effects of the present invention are more excellent.

[0061] The pyrolysis gas chromatography mass spectrometry (pyrolysis GC-MS) is carried out under the following conditions.

[0062] (Conditions) - Apparatus name: GCMS-QP2020 manufactured by Shimadzu Corporation - Pyrolysis apparatus name: Double Shot Pyrolyzer PY-2020iD manufactured by Frontier Labs - Pyrolysis temperature: 550°C - Injection port temperature: 320°C - Column used: 5% Diphenyldimethyl polysiloxane (UA-5 manufactured by GL Sciences) - Column size: Length 30 m, inner diameter 0.25 mm, film thickness 0.25 μm - Method (column temperature conditions): 70°C (3 minutes) → Heat at 10°C / minute (25 minutes) → Final temperature 320°C - Carrier gas: Ultra-high purity helium gas (total flow rate: 104 mL / minute, column flow rate 1 mL / minute) - Injection amount: 1 μL

[0063] A specific example of a method for calculating the S value is shown below. Figure 1 shows a total ion chromatogram (TIC) obtained by pyrolysis GC-MS of resin A, which will be described later. The pyrolysis GC-MS conditions are as described above. As shown in Figure 1, two peaks are present in the TIC of resin A. The retention coefficient k of the first peak (left peak) in terms of the shortest retention time is １ is 1.7, and the retention factor k of the second smallest peak (the peak on the right) is ２ The retention factor of the two peaks is 6.0 or less, so k ｎ The peak with the largest retention factor that satisfies ≦6.0 is the right peak. Since the right peak is the second peak from the shortest retention time, α in the parameter S is 2. Also, the ratio A of the area of ​​the left peak to the sum of the areas of the two peaks is １ is 40(%), and the ratio A of the area of ​​the right peak to the total area of ​​the two peaks is ２Therefore, the S value of Resin A is calculated as 1.7×40+2.8×60=236.

[0064] Examples of methods for achieving an S value of 300 or greater include polymerizing a resin using a monomer containing an aromatic hydrocarbon having a polymerizable group, and increasing the proportion of components in the aromatic hydrocarbons that have a high retention coefficient (the retention coefficient described above) (preferably components with a retention coefficient of 2 or greater, and more preferably components with a retention coefficient of 3 or greater). To achieve superior effects of the present invention, the proportion is preferably 50% by mass or greater, more preferably 70% by mass or greater, and even more preferably 90% by mass or greater. The upper limit of the proportion is not particularly limited, and is 100% by mass. It should be noted that, because aliphatic hydrocarbons are likely to decompose at the decomposition temperature (550°C) of the pyrolysis GC-MS described above, the presence of aliphatic hydrocarbons in the monomers constituting the resin is thought to have little effect on the S value.

[0065] [Preferred embodiment] The monomer constituting the specific resin preferably contains an aromatic hydrocarbon having a polymerizable group (e.g., a vinyl group, an isopropenyl group, etc.) because the effects of the present invention are more excellent. Specific examples of the aromatic hydrocarbon include styrene, α-methylstyrene, vinyltoluene, isopropenyltoluene, indene, and methylindene. Among them, vinyltoluene, isopropenyltoluene, indene, and methylindene are preferred because the effects of the present invention are more excellent, and isopropenyltoluene, indene, and methylindene are more preferred.

[0066] For reasons of better effects of the present invention, the retention coefficient of the aromatic hydrocarbons (the above-mentioned retention coefficient) is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. There is no particular upper limit to the retention coefficient, but for reasons of better effects of the present invention, it is preferably 6 or less, and more preferably 5 or less.

[0067] The monomers constituting the specific resin preferably contain aliphatic hydrocarbons (preferably aliphatic hydrocarbons containing unsaturated double bonds) in addition to the aromatic hydrocarbons described above. The aliphatic hydrocarbons may be linear, branched, or cyclic. Specific examples of the aliphatic hydrocarbons include aliphatic hydrocarbons constituting C5 fractions such as isoprene and cyclopentadiene.

[0068] When the monomer constituting the specific resin contains aliphatic hydrocarbons (e.g., C5 fraction) in addition to the aromatic hydrocarbons described above, the content of the aromatic hydrocarbons in the monomer is preferably 30 to 99 mass%, more preferably 50 to 97 mass%, and even more preferably 70 to 95 mass%, from the viewpoint of achieving better effects of the present invention. When the monomer constituting the specific resin contains aliphatic hydrocarbons (e.g., C5 fraction) in addition to the aromatic hydrocarbons described above, the content of the aliphatic hydrocarbons in the monomer is preferably 1 to 70 mass%, more preferably 3 to 50 mass%, and even more preferably 5 to 30 mass%, from the viewpoint of achieving better effects of the present invention.

[0069] [Molecular Weight] The weight average molecular weight (Mw) of the specific resin is preferably 100 or more and less than 100,000, more preferably 200 to 50,000, and even more preferably 500 to 10,000, for reasons of better effects of the present invention.

[0070] In the composition of the present invention, the content of the specific resin relative to the content of the aromatic vinyl-conjugated diene copolymer rubber (hereinafter also referred to as "specific resin / aromatic vinyl-conjugated diene copolymer rubber") is 1 to 100 mass %. For reasons of better effects of the present invention, the content of the specific resin / aromatic vinyl-conjugated diene copolymer rubber is preferably 10 to 90 mass %, and more preferably 20 to 80 mass %.

[0071] In the composition of the present invention, the content of the specific resin is preferably 1 to 100 parts by mass, more preferably 3 to 60 parts by mass, still more preferably 10 to 55 parts by mass, and particularly preferably 20 to 50 parts by mass, relative to 100 parts by mass of the above-mentioned conjugated diene rubber, for the reason that the effects of the present invention are more excellent.

[0072] [3] Silica The composition of the present invention contains silica. There are no particular limitations on the type of silica, and any conventionally known silica can be used. Examples of silica include wet silica, dry silica, fumed silica, and diatomaceous earth. Silica derived from biomass, such as rice husks, may also be used. The silica may be one type alone or two or more types in combination.

[0073] [CTAB] The cetyltrimethylammonium bromide (CTAB) adsorption specific surface area of ​​silica (hereinafter, "CTAB adsorption specific surface area" may also be simply referred to as "CTAB") is 70 m ２ / g or more is preferable, and 110m ２ / g or more is more preferable, and 140m ２ / g or more is more preferable, and 150m ２ The upper limit of the CTAB of silica is 300 m / g or more, from the viewpoint of obtaining better effects of the present invention (particularly, rolling resistance characteristics). ２ / g or less is preferable, and 250m ２ / g or less is more preferable, and 200m ２ Here, the CTAB adsorption specific surface area is a value measured in accordance with JIS K6430:2008, Appendix G.

[0074] [Content] In the composition of the present invention, the content of silica is preferably 10 to 300 parts by mass, more preferably 30 to 200 parts by mass, and even more preferably 50 to 150 parts by mass, per 100 parts by mass of the conjugated diene rubber, for reasons of better effects of the present invention.

[0075] [4] Silane Coupling Agent The composition of the present invention contains a silane coupling agent. The silane coupling agent is not particularly limited as long as it is a silane compound having a hydrolyzable group and an organic functional group. The hydrolyzable group is not particularly limited, but examples include an alkoxy group, a phenoxy group, a carboxyl group, and an alkenyloxy group. Of these, an alkoxy group is preferred because the effects of the present invention are more excellent. When the hydrolyzable group is an alkoxy group, the number of carbon atoms in the alkoxy group is preferably 1 to 16, and more preferably 1 to 4, because the effects of the present invention are more excellent. Examples of alkoxy groups having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, and a propoxy group.

[0076] The organic functional group is not particularly limited, but is preferably a group capable of forming a chemical bond with an organic compound, such as an epoxy group, a vinyl group, an acryloyl group, a methacryloyl group, an amino group, a sulfide group, a mercapto group, a blocked mercapto group (protected mercapto group) (e.g., an octanoylthio group), and the like. Among these, a sulfide group (particularly a disulfide group or a tetrasulfide group), a mercapto group, or a blocked mercapto group is preferred because the effects of the present invention are more excellent. The silane coupling agent may be used alone or in combination of two or more.

[0077] The silane coupling agent is preferably a sulfur-containing silane coupling agent, since this provides a better effect of the present invention.

[0078] Specific examples of the silane coupling agent include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide, triethoxysilylpropyl-methacrylate-monosulfide, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, and 3-octanoylthio-1-propyltriethoxysilane. One of these may be used alone, or two or more may be used in combination.

[0079] A preferred embodiment of the silane coupling agent is a silane coupling agent having the above-mentioned protected mercapto group (blocked mercapto group). This provides better effects of the present invention. The protected mercapto group is a group represented by *-S-R (R: substituent, *: bonding position). Examples of the substituent include aliphatic hydrocarbon groups, aromatic hydrocarbon groups (aryl groups), and combinations thereof. The aliphatic hydrocarbon group may be linear, branched, or cyclic. Specific examples of the aliphatic hydrocarbon group include linear or branched alkyl groups (particularly those having 1 to 30 carbon atoms), linear or branched alkenyl groups (particularly those having 2 to 30 carbon atoms), and linear or branched alkynyl groups (particularly those having 2 to 30 carbon atoms). Examples of the aromatic hydrocarbon group include aromatic hydrocarbon groups having 6 to 18 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl. The substituent is preferably an aliphatic hydrocarbon group, and more preferably an alkyl group, because this provides better effects of the present invention. For reasons of better effects of the present invention, the number of carbon atoms in the aliphatic hydrocarbon group (particularly the alkyl group) is preferably 1 to 20, and more preferably 5 to 10. The carbon atoms in the aliphatic hydrocarbon group (particularly the alkyl group) may be -O-, -C(=O)-, -C(=O)-O-, -O-C(=O)-O-, -S-, -S(=O)-, -SO２ -, -NR- (R: may be substituted with a hydrogen atom, a substituent, or a group that is a combination of these groups). The substituent is preferably an acyl group (particularly an octanoyl group) because the effects of the present invention are more excellent.

[0080] A specific example of a silane coupling agent having a protected mercapto group (blocked mercapto group) is 3-octanoylthiopropyltriethoxysilane (the compound shown below).

[0081]

[0082] [Content] In the composition of the present invention, the content of the silane coupling agent is not particularly limited, but in order to obtain better effects of the present invention, the content is preferably 1 to 20 parts by mass, more preferably 2 to 20 parts by mass, and even more preferably 5 to 15 parts by mass, per 100 parts by mass of the above-mentioned conjugated diene rubber.

[0083] In addition, in the composition of the present invention, the content of the silane coupling agent relative to the content of silica described above is preferably 1 to 20 mass%, and more preferably 5 to 15 mass%, because this provides better effects of the present invention.

[0084] [5] Optional Components The composition of the present invention may contain components (optional components) other than the above-mentioned components, as necessary. Examples of such components include resins other than the specific resin, fillers other than silica (preferably carbon black or aluminum hydroxide), the specific alkyltriethoxysilane described below, thermally expandable microcapsules, zinc oxide (zinc white), stearic acid, antioxidants, waxes, processing aids, liquid polymers, thermosetting resins, vulcanizing agents (e.g., sulfur), vulcanization accelerators (accelerators), vulcanization activators, and other additives commonly used in rubber compositions.

[0085] [Carbon Black] The composition of the present invention preferably contains carbon black because the effects of the present invention are more excellent. The carbon black may be used alone or in combination of two or more types. The carbon black is not particularly limited, and various grades of carbon black such as SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, IISAF-HS, HAF-HS, HAF, HAF-LS, FEF, GPF, and SRF may be used.

[0086] [N ２ SA] The nitrogen adsorption specific surface area (N ２ SA) is not particularly limited, but is preferably 50 to 200 m because the effect of the present invention is more excellent. ２ / g, and 70 to 150m ２ Here, the nitrogen adsorption specific surface area (N2SA) is a value obtained by measuring the amount of nitrogen adsorbed onto the surface of carbon black in accordance with JIS K6217-2:2001 "Part 2: Determination of specific surface area - Nitrogen adsorption method - Single point method."

[0087] [Content] In the composition of the present invention, the content of carbon black is not particularly limited, but in order to achieve better effects of the present invention, the content is preferably 1 to 130 parts by mass, more preferably 2 to 100 parts by mass, and even more preferably 2 to 50 parts by mass, per 100 parts by mass of the above-mentioned conjugated diene rubber.

[0088] [Specific alkyltriethoxysilane] The composition of the present invention preferably contains an alkyltriethoxysilane represented by the following general formula (I) (hereinafter also referred to as "specific alkyltriethoxysilane"), because this improves the dispersibility of silica and makes the effects of the present invention more excellent.

[0089]

[0090] In the above general formula (I), R １represents an alkyl group having 7 to 20 carbon atoms. Et represents an ethyl group. Specific examples of the alkyl group having 7 to 20 carbon atoms include a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group. Of these, an octyl group and a nonyl group are preferred because they provide better effects of the present invention.

[0091] [Content] In the composition of the present invention, the content of the specific alkyltriethoxysilane is not particularly limited, but in order to achieve better effects of the present invention, it is preferably 2.0 to 15.0 mass %, more preferably 2.5 to 12.5 mass %, and even more preferably 3.0 to 10.0 mass %, relative to the content of silica.

[0092] [6] Method for Preparing Rubber Composition for Tires The method for producing the composition of the present invention is not particularly limited, and specific examples thereof include a method in which the above-mentioned components are kneaded using a known method or apparatus (e.g., a Banbury mixer, a kneader, a roll, etc.). When the composition of the present invention contains sulfur or a vulcanization accelerator, it is preferable to first mix the components other than the sulfur and the vulcanization accelerator at a high temperature (preferably 100 to 160°C), cool the mixture, and then mix the sulfur or vulcanization accelerator. In addition, the composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[0093] [II] Tire The tire of the present invention is a tire manufactured using the composition of the present invention described above. The tire of the present invention is preferably a pneumatic tire, and can be filled with air, an inert gas such as nitrogen, or other gases.

[0094] Fig. 2 shows a partial cross-sectional schematic view of a tire showing one example of an embodiment of the tire of the present invention, although the tire of the present invention is not limited to the embodiment shown in Fig. 2.

[0095] In Figure 2, reference numeral 1 denotes a bead portion, reference numeral 2 denotes a sidewall portion, and reference numeral 3 denotes a tire tread portion. A carcass layer 4 having fiber cords embedded therein is mounted between the pair of left and right bead portions 1, and the ends of this carcass layer 4 are folded back and wound up around a bead core 5 and a bead filler 6 from the inside to the outside of the tire. In the tire tread portion 3, a belt layer 7 is disposed around the entire circumference of the tire on the outside of the carcass layer 4. In the bead portion 1, a rim cushion 8 is disposed in the portion that contacts the rim. At least one of reference numerals 2-3, 5-6, and 8 (preferably reference numeral 3) is formed from the composition of the present invention described above.

[0096] The tire of the present invention can be manufactured, for example, by a conventionally known method. The gas to be filled into the tire can be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium.

[0097] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0098] [Production of Rubber Composition for Tires] The components shown in Tables 1 and 2 below were blended in the ratios (parts by mass) shown in the tables. Specifically, first, the components except for sulfur and the vulcanization accelerator were kneaded in a 1.7-liter internal mixer for 5 minutes, and then released when the temperature reached 150°C to obtain a master batch. Next, sulfur and the vulcanization accelerator were kneaded into the obtained master batch using an open roll to obtain a rubber composition for tires.

[0099] [Wet Grip Performance and Rolling Resistance Properties] The obtained rubber composition for tires was vulcanized at 170°C for 15 minutes using a mold of a predetermined shape (inner dimensions: length 150 mm, width 150 mm, thickness 2 mm) to produce a vulcanized rubber sheet. Tan δ of the obtained vulcanized rubber sheet was measured at temperatures of 0°C and 60°C using a viscoelasticity spectrometer (manufactured by Toyo Seiki Seisaku-sho, Ltd.) in accordance with JIS K6394:2007 under conditions of an elongation deformation strain rate of 10%±2% and a vibration frequency of 20 Hz. Wet grip performance was evaluated from tan δ at 0°C, and rolling resistance properties were evaluated from the reciprocal of tan δ at 60°C. Wet grip performance is shown in Tables 1 and 2 as an index (tan δ (0°C)), with the value of Comparative Example 1 set to 100. A higher index indicates better wet grip performance. In practice, an index greater than 100 is preferable. The rolling resistance characteristics are shown in Tables 1 and 2 as an index (tan δ (60°C)) with the value of Comparative Example 1 being 100. A larger index means better rolling resistance characteristics (smaller rolling resistance). In practice, an index of greater than 100 is preferable.

[0100] [Heat sagging resistance] The obtained rubber composition for tires was vulcanized at 170 ° C. for 15 minutes using a mold of a predetermined shape (inner dimensions: length 150 mm, width 150 mm, thickness 2 mm) to produce a vulcanized rubber sheet. The hardness (Type A durometer hardness) of the obtained vulcanized rubber sheet was measured at 20 ° C. and 100 ° C. in accordance with JIS K6253-3. The value obtained by subtracting the hardness value at 100 ° C. from the hardness value at 20 ° C. was calculated, and the heat sagging resistance was evaluated from the reciprocal of that value. The heat sagging resistance is shown in Tables 1 and 2 as an index (Hs (20-100 ° C.)), with the value of Comparative Example 1 set to 100. The larger the index, the better the heat sagging resistance. In practice, an index greater than 100 is preferable.

[0101]

[0102]

[0103] In Tables 1 and 2, the "aromatic proton ratio" and "S value" columns respectively show the aromatic proton ratio and S value of the resin (resins A to F) used in each example. In addition, in Tables 1 and 2, the "resin / aromatic vinyl-conjugated diene copolymer rubber" column shows the content (mass%) of the resin (resins A to F) relative to the content of the aromatic vinyl-conjugated diene copolymer rubber in each example.

[0104] [Resins] The resins in Tables 1 and 2 are as follows. Note that resins D to F have an aromatic proton ratio of 20% or more and an S value of 300 or more, and therefore all fall under the above-mentioned specific resins. On the other hand, resins A and B have an S value of less than 300, and therefore none of them fall under the above-mentioned specific resins. Furthermore, resin C has an aromatic proton ratio of less than 20%, and therefore does not fall under the above-mentioned specific resins. Furthermore, the Mw of resins A to F is all less than 100,000. Resin A: Resin obtained by thermally polymerizing α-methylstyrene and styrene in a ratio of 6 / 5 (mass ratio) (aromatic proton ratio: 54%, S value: 236) Resin B: Resin obtained by thermally polymerizing styrene and indene in a ratio of 2 / 3 (mass ratio) (aromatic proton ratio: 53%, S value: 283) Resin C: Resin obtained by thermally polymerizing C5 fraction and indene in a ratio of 4 / 1 (mass ratio) (aromatic proton ratio: 12%, S value: 355) Resin D: Resin obtained by thermally polymerizing styrene, α-methylstyrene, vinyltoluene, indene, and isopropenyltoluene in a ratio of 3 / 14 / 68 / 13 / 2 (mass ratio) (aromatic proton ratio: 37%, S value: 308, Mw: 1522) Resin E: A resin obtained by thermally polymerizing a C5 fraction, styrene, α-methylstyrene, vinyltoluene, indene, isopropenyltoluene, and methylindene in a ratio of 100 / 3 / 4 / 24 / 28 / 9 / 32 (mass ratio) (aromatic proton ratio: 25%, S value: 336, Mw: 1936). Resin F: A resin obtained by thermally polymerizing a C5 fraction, indene, and methylindene in a ratio of 10 / 63 / 27 (mass ratio) (aromatic proton ratio: 41%, S value: 390, Mw: 1037).

[0105] [Aromatic vinyl-conjugated diene copolymer rubber] In Tables 1 and 2, specific conjugated diene rubber 1, specific conjugated diene rubber 2, HPR850, and HPR840 are classified as aromatic vinyl-conjugated diene copolymer rubber. Each component is as follows. Specific conjugated diene rubber 1: See the manufacturing method below (a conjugated diene rubber manufactured by the manufacturing method for conjugated diene rubber comprising the first and second steps described above, and corresponds to the specific conjugated diene rubber described above) Specific conjugated diene rubber 2: See the manufacturing method below (a conjugated diene rubber manufactured by the manufacturing method for conjugated diene rubber comprising the first and second steps described above, and corresponds to the specific conjugated diene rubber described above) HPR850: SSBR HPR850 manufactured by ENEOS Material Corporation (does not correspond to the specific conjugated diene rubber) HPR840: SSBR HPR840 manufactured by ENEOS Material Corporation (does not correspond to the specific conjugated diene rubber)

[0106] <Specific Conjugated Diene Rubber 1> 70.0 g of cyclohexane and 0.77 mmol of tetramethylethylenediamine were added to an 800 ml ampoule whose atmosphere had been purged with nitrogen. Furthermore, 7.69 mmol of n-butyllithium (an amount such that the amount of tetramethylethylenediamine as a polar compound per mole of n-butyllithium was 0.10 moles) was added. Next, 27.9 g of isoprene and 2.1 g of styrene were slowly added, and the mixture was allowed to react for 120 minutes in the ampoule at 50°C to obtain a polymer block (A) having an active terminal. The polymer block (A) had a weight-average molecular weight (Mw) of 6,500, a molecular weight distribution (Mw / Mn) of 1.10, a styrene monomer unit content of 7.0 mass%, an isoprene monomer unit content of 93.0 mass%, and a vinyl bond content of 7.7 mass%.

[0107] An autoclave equipped with a stirrer was charged with 4,000 g of cyclohexane, 2.69 mmol of tetramethylethylenediamine, 474 g of 1,3-butadiene, and 126 g of styrene under a nitrogen atmosphere, and then the entire amount of polymer block (A) having active ends obtained above was added. Polymerization was initiated at 50°C (the amount of tetramethylethylenediamine as a polar compound present in the reaction system was 0.45 mol per mol of n-butyllithium used). Ten minutes after the start of polymerization, 376 g of 1,3-butadiene and 24 g of styrene were continuously added over 60 minutes. The maximum temperature during the polymerization reaction was 75°C. After the continuous addition was completed, the polymerization reaction was continued for another 10 minutes. After confirming that the polymerization conversion rate had reached a range of 95% to 100%, 2.44 g of a polyorganosiloxane represented by the following formula (11) was added in the form of a 40% by mass xylene solution (equivalent to 1.1 times the molar amount of n-butyllithium used, converted into the number of repeating units of the siloxane structure (—Si—O—) in the polyorganosiloxane) and allowed to react for 30 minutes. Thereafter, as a polymerization terminator, methanol in an amount equivalent to 2 times the molar amount of n-butyllithium used was added to obtain a solution containing a conjugated diene rubber. To this solution, 0.15 parts of Irganox 1520L (manufactured by BASF) was added as an antioxidant, relative to 100 parts of the conjugated diene rubber. The solvent was then removed by steam stripping, and the mixture was vacuum dried at 60 ° C. for 24 hours to obtain a solid conjugated diene rubber. The obtained conjugated diene rubber is designated specific conjugated diene rubber 1. The specific conjugated diene rubber 1 had a weight average molecular weight (Mw) of 450,000, a coupling rate of 56.8%, a styrene monomer (aromatic vinyl monomer) unit content of 15.0% by mass, a vinyl bond content of 30.0% by mass, a glass transition temperature (Tg) of -63°C, and a molecular weight distribution (Mw / Mn) of 1.6.

[0108]

[0109] In the above formula (11), X １ , X ４ , R １ ~R ３ and R ５ ~R ８is a methyl group. In the above formula (11), m is 80 and k is 120. In the above formula (11), X ２ is a group represented by the following formula (12) (where * represents a bonding position).

[0110]

[0111] <Specific Conjugated Diene Rubber 2> 50.0 g of cyclohexane and 0.66 mmol of tetramethylethylenediamine were added to a nitrogen-purged 100 ml ampoule, followed by 6.6 mmol of n-butyllithium. Next, 11.61 g of isoprene and 0.87 g of styrene were slowly added, and the mixture was allowed to react for 120 minutes in the ampoule at 50°C to obtain a polymer block (A) having an active terminal. The polymer block (A) had a weight-average molecular weight (Mw) of 3,500, a molecular weight distribution (Mw / Mn) of 1.10, an aromatic vinyl monomer (styrene monomer) unit content of 7.0 mass%, an isoprene monomer unit content of 93.0 mass%, and a vinyl bond content of 7.7 mass%.

[0112] Next, 4,000 g of cyclohexane, 11.1 mmol of tetramethylethylenediamine, 393.0 g of 1,3-butadiene, and 207.0 g of styrene were charged into an autoclave equipped with a stirrer under a nitrogen atmosphere, and the entire amount of polymer block (A) having active ends obtained above was added, and polymerization was initiated at 40°C. 10 minutes after the start of polymerization, 337.0 g of 1,3-butadiene and 63.0 g of styrene were continuously added over 40 minutes. The maximum temperature during the polymerization reaction was 60°C. After the completion of the continuous addition, the polymerization reaction was continued for another 20 minutes, and after confirming that the polymerization conversion rate was in the range of 95% to 100%, 2.13 g of the polyorganosiloxane represented by the above formula (11) in the state of a 40% by mass concentration xylene solution (converted to the number of repeating units of the siloxane structure (-Si-O-) in the polyorganosiloxane, an amount equivalent to 1.1 times the molar amount of n-butyllithium used) was added and allowed to react for 30 minutes. Thereafter, as a polymerization terminator, an amount of methanol equivalent to twice the molar amount of n-butyllithium used was added to obtain a solution containing a conjugated diene rubber. To this solution, 0.15 parts of Irganox 1520L (manufactured by Ciba Specialty Chemicals) was added as an antioxidant, relative to 100 parts of conjugated diene rubber, and the solvent was removed by steam stripping and the mixture was vacuum dried at 60 ° C. for 24 hours to obtain a solid conjugated diene rubber. The obtained conjugated diene rubber is designated as specific conjugated diene rubber 2. The specific conjugated diene rubber 2 had a weight average molecular weight (Mw) of 488,000, a coupling rate of 60.2%, an aromatic vinyl monomer (styrene monomer) unit content of 26.6% by mass, a vinyl bond content of 60.4% by mass, a glass transition temperature (Tg) of −22° C., and a molecular weight distribution (Mw / Mn) of 1.4.

[0113] [Components other than resin and aromatic vinyl-conjugated diene copolymer rubber] In Tables 1 and 2, the components other than resin and aromatic vinyl-conjugated diene copolymer rubber are as follows: Silica: ZEOSIL 1165MP manufactured by Solvay (CTAB adsorption specific surface area: 160 m ２ / g) CB: Showblack N339 carbon black manufactured by Cabot Japan Corp. Silane coupling agent A: Si69 manufactured by Evonik (not a silane coupling agent having a protected mercapto group) Silane coupling agent B: 3-octanoylthiopropyltriethoxysilane (compound below) (corresponding to a silane coupling agent having a protected mercapto group)

[0114]

[0115] Alkylsilane: KBE-3083 octyltriethoxysilane manufactured by Shin-Etsu Chemical Co., Ltd. (Alkylsilane corresponds to the specific alkyltriethoxysilane described above) Oil: Extract No. 4S manufactured by Shell Lubricants Japan Co., Ltd. Zinc oxide: Zinc oxide type 3 manufactured by Seido Chemical Industry Co., Ltd. Stearic acid: Beads stearate YR manufactured by NOF Corporation Antiaging agent: 6PPD manufactured by Flexis Co., Ltd. Sulfur: Kinka-jirushi oil-filled fine sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noccela CZ-G (CZ) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Soxinol D-G (DPG) manufactured by Sumitomo Chemical Co., Ltd.

[0116] [Summary of Tables 1-2] As can be seen from Tables 1-2, Examples 1-8, which contain a specific conjugated diene rubber at a predetermined ratio relative to the conjugated diene rubber content and a specific resin at a predetermined ratio relative to the aromatic vinyl-conjugated diene copolymer rubber content, exhibited excellent wet grip performance, rolling resistance characteristics, and heat sagging resistance. Comparing Examples 1-3 (comparison between embodiments that differ only in the type of specific resin), Examples 2-3, in which the specific resin had an S value of 330 or more, exhibited better wet grip performance, rolling resistance characteristics, and heat sagging resistance. Of these, Example 3, in which the specific resin had an S value of 350 or more, exhibited even better wet grip performance, rolling resistance characteristics, and heat sagging resistance. Comparing Examples 4-5 (comparison between embodiments that differ only in the presence or absence of alkylsilane), Example 5, which contained a specific alkyltriethoxysilane, exhibited better wet grip performance, rolling resistance characteristics, and heat sagging resistance. In addition, from a comparison between Example 1, Example 6, and Example 7 (comparison between embodiments using Resin D as the specific resin), Example 1, in which the specific resin / aromatic vinyl-conjugated diene copolymer rubber is 10 to 90% by mass, exhibited better rolling resistance characteristics and heat sagging performance. Also, from a comparison between Example 3 and Example 8 (comparison of the type of silane coupling agent), Example 8, which used Silane Coupling Agent B, exhibited better wet grip performance, rolling resistance characteristics, and heat sagging performance.

[0117] On the other hand, Comparative Examples 1 to 3, which did not contain the specific conjugated diene rubber, had insufficient wet grip performance, rolling resistance, and heat sagging resistance. Comparative Examples 4 to 6, which contained a resin other than the specific resin instead of the specific resin, also had insufficient wet grip performance, rolling resistance, and heat sagging resistance. Comparative Example 7, in which the specific conjugated diene rubber / conjugated diene rubber ratio was less than 30% by mass, had insufficient heat sagging resistance. Comparative Example 8, which did not contain silica, had insufficient rolling resistance.

[0118] REFERENCE SIGNS LIST 1 Bead portion 2 Sidewall portion 3 Tire tread portion 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Rim cushion

Claims

1. It contains a conjugated diene rubber including an aromatic vinyl-conjugated diene copolymer rubber, silica, a silane coupling agent, and a resin. The aromatic vinyl-conjugated diene copolymer rubber includes a specific conjugated diene rubber, The aforementioned specific conjugated diene rubber is produced by a method for producing conjugated diene rubber comprising: a first step of polymerizing monomers containing a conjugated diene compound and an aromatic vinyl compound in an inert solvent using a polymerization initiator to obtain a conjugated diene polymer chain having active ends; and a second step of adding a polyorganosiloxane represented by the following general formula (1) to the conjugated diene polymer chain having active ends in a ratio of 1 mole or more per mole of polymerization initiator used in the first step, calculated in terms of the number of repeating units of the siloxane structure (-Si-O-) in the polyorganosiloxane, and reacting the two. The aforementioned resin is a resin in which the proportion of aromatic hydrocarbon-derived protons determined by the NMR method is 20% or more, and the following parameter S is 300 or more. The content of the specified conjugated diene rubber relative to the content of the conjugated diene rubber is 30% by mass or more. A rubber composition for tires, wherein the content of the resin relative to the content of the aromatic vinyl-conjugated diene copolymer rubber is 1 to 100% by mass. [Math 1] Here, k ｎ α represents the retention coefficient of the nth peak with the smallest retention time in the total ion chromatogram obtained by pyrolysis gas chromatography-mass spectrometry of the resin, and α is k ｎ The above n represents the peak of the maximum retention coefficient that satisfies ≤ 6.0, and A ｎ is, k ｎ This represents the ratio (%) of the area of ​​the nth peak to the sum of the areas of all peaks that satisfy ≤ 6.

0. 【number】 In general formula (1), R １ ~R ８ These are alkyl groups having 1 to 6 carbon atoms, or aryl groups having 6 to 12 carbon atoms, and these may be the same or different from each other. X １ and X ４ This group is selected from the group consisting of C1-C6 alkyl groups, C6-C12 aryl groups, C1-C5 alkoxy groups, and C4-C12 groups containing epoxy groups, and these groups may be the same or different from each other. X ２ is an alkoxy group having 1 to 5 carbon atoms or a group having 4 to 12 carbon atoms containing an epoxy group, and a plurality of X ２ may be the same as or different from each other X ３ This is a group containing 2 to 20 repeating units of alkylene glycol, X ３ When there are multiple items, they may be identical or different from one another. m is an integer between 3 and 200, n is an integer between 0 and 200, and k is an integer between 0 and 200, and m + n + k is greater than or equal to 3.

2. The specific surface area of ​​the silica used for adsorption of cetyltrimethylammonium bromide is 140 m². ２ The tire rubber composition according to claim 1, wherein the amount is 1 / g or more.

3. Furthermore, it contains an alkyltriethoxysilane represented by the following general formula (I), The tire rubber composition according to claim 1, wherein the content of the alkyltriethoxysilane is 2.0 to 15.0% by mass relative to the content of the silica. 【Chemistry 2】 In general formula (I), R １ represents an alkyl group with 7 to 20 carbon atoms, and Et represents an ethyl group.

4. A tire manufactured using the tire rubber composition described in any one of claims 1 to 3.

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