JP2016003246A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition good in workability of an unvulcanized rubber composition at a high temperature and excellent in high fracture resistance and low heat generation property at a working temperature (room temperature or the like) of a vulcanized product of the rubber composition and a tire using the rubber composition.SOLUTION: There are provided a rubber composition containing a thermal reversible crosslinkable conjugated diene polymer having a crosslink cleavage initiation temperature at 100°C or less and the content of a vinyl binding of a conjugated diene compound part of 30 mol% or less, and a tire using the rubber composition for one or more member.

Description

  The present invention relates to a rubber composition having good workability of an unvulcanized rubber composition at a high temperature and high reinforcement at the use temperature of the vulcanized product of the rubber composition (100 ° C. or lower). The present invention relates to a tire using a rubber composition as a tread.

It is known that the higher the molecular weight of the conjugated diene polymer, the better the high fracture, the high wear resistance and the low loss.
On the other hand, the molecular weight is preferably not too high in order to ensure the workability of the unvulcanized rubber composition at the time of blending or the like. When a high molecular weight conjugated diene polymer is blended, since the torque in the kneading apparatus is large, molecular chain scission is likely to occur, and it is difficult to efficiently maintain the high molecular weight. In order to improve these problems, a method of blending a conjugated diene polymer having an appropriate molecular weight capable of ensuring workability has been proposed. (Patent Document 1) However, a decrease in physical properties and the like is observed by blending a low molecular weight.
It is also common to improve the physical properties by modifying the polymer by modifying the polymer. (Patent Document 2) However, when the unvulcanized rubber composition is kneaded, the additive and the rubber component are gelled, resulting in poor workability. The problem of deterioration in dispersion resistance due to bonding of the conjugated diene polymer and additives, resulting in poor dispersion and poor crystallization of the conjugated diene polymer due to hindering crystallization of the polymer. There was a point.

JP 2005-350595 A JP 2005-008770 A

  Under such circumstances, the present invention has good workability of the unvulcanized rubber composition at high temperature, and has high fracture resistance at the use temperature (such as room temperature) of the vulcanized product of the rubber composition. It is an object of the present invention to provide a rubber composition excellent in low heat build-up and a tire using the rubber composition.

In order to solve the above-mentioned problems, the present inventor has intensively studied to give the rubber composition the property that the unvulcanized rubber composition at high temperature has good workability and high reinforcement at room temperature. As a result of overlapping, it was found that the subject of the present invention can be solved by blending a specific modified conjugated diene polymer as a rubber component.
That is, the present invention
[1] A rubber composition comprising a thermoreversible crosslinkable conjugated diene polymer having a crosslinking initiation temperature at 100 ° C. or lower and a vinyl bond content of the conjugated diene compound portion of 30 mol% or lower, and [ 2] A tire using the rubber composition according to the above [1] as one or more members,
Is to provide.

In the thermoreversible crosslinkable conjugated diene polymer used in the rubber composition of the present invention, the modified molecular chain ends are bonded at a low temperature by an interaction such as a hydrogen bond, and the bonds are cleaved at a high temperature. Utilizing this characteristic, even a conjugated diene polymer having a low molecular weight is bonded when used near room temperature, and exhibits high fracture resistance, excellent wear resistance, and good low heat generation. On the other hand, in the kneading step of the rubber composition at a high temperature (for example, 100 ° C. or higher), the hydrogen bond and the like are broken, so that the molecular weight of the conjugated diene polymer is lowered and the workability is improved. .
Further, when the tire runs at a high speed, for example, the temperature becomes 100 ° C. or higher, and the loss tangent of the vulcanized rubber composition increases due to the cleavage of the bonds between some conjugated diene polymers, and the vulcanized rubber composition The fracture resistance at high temperature of the product could be improved, and the fracture resistance could be improved by reducing the vinyl bond content. That is, by controlling the molecular weight of the thermoreversible crosslinkable conjugated diene polymer, it was possible to further improve the workability of the unvulcanized rubber composition, the fracture resistance and the low heat build-up of the vulcanized rubber composition. .

The rubber composition of the present invention contains a thermoreversible crosslinkable conjugated diene polymer having a crosslinking initiation temperature at 100 ° C. or lower and a vinyl bond content in the conjugated diene compound portion of 30 mol% or lower. Features.
Here, the method for measuring the crosslinking cleavage initiation temperature is a dynamic shear viscoelasticity tester, using dynamic shear viscoelasticity tester, taking dynamic data by taking data in increments of 1 ° C. in a range of 30 ° C. to 150 ° C. with a dynamic strain of 1% and a frequency of 15 Hz. The temperature dispersion of the elastic modulus G ″ is measured, and the decrease start temperature of G ″ is set as the crosslinking start temperature.
Moreover, the measuring method of vinyl bond content exceeding 2 mol% is based on the Morero method by infrared absorption spectrum, and the measuring method of vinyl bond content of 2 mol% or less is described in Unexamined-Japanese-Patent No. 2008-291096. Based on Fourier transform infrared spectroscopy.

In the present invention, the thermoreversible crosslinkability means that the crosslink is cleaved at a predetermined temperature (crosslink cleavage start temperature: 100 ° C., for example) or higher, and a crosslink bond is formed below the predetermined temperature. It means regenerating. In this case, the term “crosslinking” refers to a bond having high temperature dependency such as a hydrogen bond. By this crosslinking, a polymer network of thermoreversible crosslinkable conjugated diene polymer is formed, and the fracture resistance and low heat build-up of the vulcanized rubber composition at the normal use temperature of the tire are further improved.
By having a crosslinking initiation temperature at 100 ° C. or lower, the workability of the unvulcanized rubber composition at high temperature is improved, and high fracture resistance is obtained when the vulcanized rubber composition is used near room temperature. Abrasion resistance and good low heat build-up can be enjoyed. In this respect, the crosslinking initiation temperature is preferably 50 ° C. or higher, and more preferably 60 ° C. or higher.
The reason why the vinyl bond content in the conjugated diene compound portion is 30 mol% or less is to improve the fracture resistance of the vulcanized rubber composition.

The rubber composition of the present invention comprises a thermoreversible crosslinkable conjugated diene polymer having a crosslinking cleavage initiation temperature of 100 ° C. or less and a vinyl bond content of a conjugated diene compound portion of 30 mol% or less and natural rubber. It is preferable to include.
In the rubber composition of the present invention, when the thermoreversible crosslinkable conjugated diene polymer and natural rubber are contained, the stretched crystallinity is increased by expanding the polymer network in the rubber by interacting with the non-rubber component contained in the natural rubber. improves.
Natural rubber contains non-rubber components in addition to rubber, and proteins and phospholipids are added to the end of natural rubber. As a result, the natural rubber has a higher order structure through this end. The present inventor has confirmed that the natural rubber acts on natural rubber by adding an ionomer to the end of the natural rubber, and has high fracture resistance, excellent wear resistance, and good low heat build-up. It could be applied to the composition. The mechanism for improving the physical properties of these vulcanized rubber compositions is to increase the molecular weight by networking (improvement of fracture resistance and low heat build-up), and to reduce the occurrence of loss due to the network breaking at high temperature and high strain, that is, This is an improvement in destructibility.

The thermoreversible crosslinkable conjugated diene polymer according to the rubber composition of the present invention comprises an organic alkali metal compound or an organic alkaline earth metal as a polymerization initiator, and one or more conjugated diene compounds or one or more conjugated diene compounds and It is preferably obtained by anionic polymerization of an aromatic vinyl compound. The production method is not particularly limited, and any of a solution polymerization method, a gas phase polymerization method, and a bulk polymerization method can be used, but a solution polymerization method is particularly preferable. Moreover, any of a batch type and a continuous type may be sufficient as the superposition | polymerization form.
Of the organic alkali metal compounds and organic alkaline earth metals as polymerization initiators, organic alkali metal compounds are preferable, and organic lithium metal compounds are particularly preferable.

  Examples of the conjugated diene compound include isoprene, 1,3-butadiene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, and 1,3-hexadiene. One or more selected compounds are preferably exemplified. These may be used singly or in combination of two or more. Among these, isoprene, 1,3-butadiene and 2,3-dimethyl-1,3-butadiene are more preferable, isoprene, 1,3-butadiene is particularly preferred.

  The thermoreversible crosslinkable conjugated diene polymer according to the rubber composition of the present invention is preferably polymerized with at least one conjugated diene compound. If desired, the conjugated diene compound and an aromatic vinyl compound are copolymerized. You may let them. Examples of the aromatic vinyl compound used in the copolymerization with the conjugated diene compound include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, and 4-cyclohexyl. Preferable examples include one or more compounds selected from styrene and 2,4,6-trimethylstyrene. These may be used alone or in combination of two or more, and among these, styrene is particularly preferable.

Furthermore, when copolymerization is carried out using a conjugated diene compound and an aromatic vinyl compound as monomers, the use of 1,3-butadiene and styrene, respectively, is practical in terms of the availability of monomers, and The anionic polymerization characteristics are particularly suitable because of excellent living characteristics.
When the solution polymerization method is used, the monomer concentration in the solvent is preferably 5 to 50% by mass, more preferably 10 to 30% by mass. In addition, when copolymerizing using a conjugated diene compound and an aromatic vinyl compound, the content of the aromatic vinyl compound in the charged monomer mixture is preferably in the range of 0 to 55% by mass.

  Although there is no restriction | limiting in particular as an organic lithium compound of a polymerization initiator, Hydrocarbyl lithium, a dilithium compound, and a lithium amide compound are used preferably. When hydrocarbyl lithium is used, a conjugated diene copolymer having a hydrocarbyl group at the polymerization initiation terminal and the other terminal being a polymerization active site (a molecular chain terminal capable of having a functional group described later) is obtained. . When a dilithium compound is used, a conjugated diene-based copolymer having both ends at the polymerization active site (molecular chain end that can have a functional group described later) is obtained. When a lithium amide compound is used, a conjugated diene copolymer having a nitrogen-containing group at the polymerization initiation terminal and the other terminal being a polymerization active site (a molecular chain terminal capable of having a functional group described later) is obtained. It is done.

  As the hydrocarbyl lithium, those having a hydrocarbyl group having 2 to 20 carbon atoms are preferable, for example, ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-octyl lithium, n-decyl. Examples include lithium, phenyllithium, 2-naphthyllithium, 2-butyl-phenyllithium, 4-phenyl-butyllithium, cyclohexyllithium, cyclobenthyllithium, and a reaction product of diisopropenylbenzene and butyllithium. Of these, n-butyllithium is particularly preferred.

  Moreover, as a dilithium compound, it does not specifically limit but a well-known thing can be used. For example, Japanese Patent Publication No. 1-53681 discloses a method for producing a dilithium polymerization initiator by reacting a monolithium compound with a disubstituted vinyl or an alkenyl group-containing aromatic hydrocarbon in the presence of a tertiary amine. Has been. As the monolithium compound, those described above are used, and among them, sec-butyllithium is preferable.

Examples of the tertiary amine used when producing a dilithium compound as a polymerization initiator include lower aliphatic amines such as trimethylamine and triethylamine, N, N-diphenylmethylamine, and the like, and triethylamine is particularly preferable.
Examples of the disubstituted vinyl or alkenyl group-containing aromatic hydrocarbon include 1,3- (diisopropenyl) benzene, 1,4- (diisopropenyl) benzene, 1,3-bis (1-ethylethenyl). ) Benzene, 1,4-bis (1-ethylethenyl) benzene and the like are preferred.

  On the other hand, examples of the lithium amide compound include lithium hexamethylene imide, lithium pyrrolidide, lithium piperide, lithium heptamethylene imide, lithium dodecamethylene imide, lithium dimethyl amide, lithium diethyl amide, lithium dibutyl amide, lithium dipropyl amide, and lithium disulfide. Heptylamide, lithium dihexylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiverazide, lithium ethylpropylamide, lithium ethylbutyramide, lithium ethylbenzylamide, lithium methylphenethylamide, etc. Is mentioned. Among these, in view of the interaction effect on carbon black and the ability to initiate polymerization, cyclic lithium amides such as lithium hexamethylene imide, lithium pyrrolidide, lithium piperide, lithium heptamethylene imide, and lithium dodecamethylene imide are preferable, In particular, lithium hexamethylene imide and lithium pyrrolidide are suitable.

  As these lithium amide compounds, those prepared in advance from a secondary amine and an organic lithium compound can be used for polymerization, but they can also be prepared in a polymerization system (in-situ). The amount of the polymerization initiator used is preferably selected in the range of 0.2 to 20 mmol per 100 g of monomer.

A method for producing a conjugated diene polymer by anionic polymerization using the organolithium compound as a polymerization initiator is not particularly limited, and a conventionally known method can be used.
Specifically, in an organic solvent inert to the reaction, for example, a hydrocarbon solvent such as an aliphatic, alicyclic or aromatic hydrocarbon compound, two or more conjugated diene compounds or conjugated diene compounds and aromatic vinyl are used. The desired conjugated diene copolymer can be obtained by subjecting the compound to anionic polymerization in the presence of the randomizer used, if desired, using the organolithium compound as a polymerization initiator.

  The hydrocarbon solvent is preferably one having 3 to 8 carbon atoms, such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene and trans-2. -Butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene and the like. These may be used alone or in combination of two or more.

  The randomizer used as desired is control of the microstructure of the conjugated diene copolymer, for example, 1,2 bond of butadiene moiety in butadiene polymer or butadiene-styrene copolymer, 3,4 bond in isoprene polymer. Of the compound having an effect of controlling the composition distribution of the monomer unit in the conjugated diene compound-aromatic vinyl compound copolymer, for example, randomizing the butadiene unit or the styrene unit in the butadiene-styrene copolymer. That is. The randomizer is not particularly limited, and any one of known compounds generally used as a conventional randomizer can be appropriately selected and used. Specifically, dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, 2,2-bis (2-tetrahydrofuryl) -propane, triethylamine, pyridine, N-methylmorpholine, N, N, N ′, Examples thereof include ethers such as N′-tetramethylethylenediamine and 1,2-dipiperidinoethane, and tertiary amines. Further, potassium salts such as potassium tert-amylate and potassium tert-butoxide, and sodium salts such as sodium tert-amylate can also be used.

  These randomizers may be used individually by 1 type, and may be used in combination of 2 or more type. The amount used is preferably selected in the range of 0.01 to 1000 molar equivalents per mole of the organolithium compound.

  The temperature in this polymerization reaction is preferably selected in the range of 0 ° C to 150 ° C, more preferably 20 ° C to 130 ° C. The polymerization reaction can be carried out under generated pressure, but it is usually desirable to operate at a pressure sufficient to keep the monomer in a substantially liquid phase. That is, the pressure depends on the particular material being polymerized, the polymerization medium used and the polymerization temperature, but higher pressures can be used if desired, such pressure being a gas that is inert with respect to the polymerization reaction. Can be obtained by an appropriate method such as pressurizing.

In this polymerization, it is desirable that all raw materials involved in the polymerization, such as a polymerization initiator, a solvent, and a monomer, are obtained by removing reaction inhibitors such as water, oxygen, carbon dioxide, and protic compounds.
It is preferable that the glass transition temperature (Tg) calculated | required by the differential thermal analysis method of the conjugated diene type polymer obtained is -95 degreeC--15 degreeC. By setting the glass transition temperature in the above range, it is possible to obtain a conjugated diene copolymer that can suppress the increase in viscosity and is easy to handle.

In addition, the thermoreversible crosslinkable conjugated diene polymer according to the rubber composition of the present invention uses one or more conjugated diene compounds or one or more conjugated diene compounds using a polymerization initiator containing a lanthanum series rare earth metal compound. It is also preferable that it is obtained by coordination polymerization of an aromatic vinyl compound.
When producing a conjugated diene polymer having a polymerization active terminal by coordination polymerization using a polymerization initiator containing a lanthanum series rare earth metal compound, the following (a) component, (b) component, (c) component: Are preferably used in combination.
The component (a) used for the coordination polymerization is selected from a rare earth metal compound, a complex compound of a rare earth metal compound and a Lewis base, and the like. Here, examples of rare earth metal compounds include rare earth element carboxylates, alkoxides, β-diketone complexes, phosphates and phosphites, and Lewis bases include acetylacetone, tetrahydrofuran, pyridine, N, N. -Dimethylformamide, thiophene, diphenyl ether, triethylamine, an organic phosphorus compound, monovalent or divalent alcohol, etc. are mentioned. As the rare earth element of the rare earth metal compound, lanthanum, neodymium, praseodymium, samarium and gadolinium are preferable, and among these, neodymium is particularly preferable. Specific examples of the component (a) include neodymium tri-2-ethylhexanoate, a complex compound thereof with acetylacetone, neodymium trineodecanoate, a complex compound thereof with acetylacetone, neodymium tri-n-butoxide, and the like. It is done. These components (a) may be used alone or in combination of two or more.

The component (b) used for the coordination polymerization is selected from organoaluminum compounds. As the organoaluminum compound, specifically, a trihydrocarbyl aluminum compound represented by the formula: R ¹² ₃ Al, a hydrocarbyl aluminum hydride represented by the formula: R ¹² ₂ AlH or R ¹² AlH ₂ (wherein R ¹² are each independently a hydrocarbon group having 1 to 30 carbon atoms), hydrocarbylaluminoxane compounds having a hydrocarbon group having 1 to 30 carbon atoms, and the like. Specific examples of the organoaluminum compound include trialkylaluminum, dialkylaluminum hydride, alkylaluminum dihydride, and alkylaluminoxane. These compounds may be used alone or in combination of two or more. In addition, as (b) component, it is preferable to use aluminoxane and another organoaluminum compound in combination.

  The component (c) used in the coordination polymerization is a compound having a hydrolyzable halogen or a complex compound thereof with a Lewis base; an organic halide having a tertiary alkyl halide, benzyl halide or allyl halide; a non-coordinating anion And an ionic compound comprising a counter cation. Specific examples of the component (c) include alkylaluminum dichloride, dialkylaluminum chloride, silicon tetrachloride, tin tetrachloride, zinc chloride and Lewis base complexes such as alcohol, magnesium chloride and alcohol such as Lewis. Examples include complexes with bases, benzyl chloride, t-butyl chloride, benzyl bromide, t-butyl bromide, triphenylcarbonium tetrakis (pentafluorophenyl) borate and the like. These components (c) may be used alone or in a combination of two or more.

  The polymerization initiator is preliminarily used by using the same conjugated diene compound and / or non-conjugated diene compound as the polymerization monomer, if necessary, in addition to the components (a), (b) and (c). May be prepared. Further, part or all of the component (a) or the component (c) may be supported on an inert solid. Although the usage-amount of each said component can be set suitably, (a) component is 0.001-0.5 millimoles (mmol) normally per 100g of monomers. In addition, (b) component / (b) component is preferably 5 to 1,000, and (c) component / (b) component is preferably 0.5 to 10 in molar ratio.

The polymerization temperature in the coordination polymerization is preferably in the range of −80 ° C. to 150 ° C., more preferably in the range of −20 ° C. to 120 ° C. Moreover, as a solvent used for coordination polymerization, a hydrocarbon solvent inert to the reaction exemplified in the above-mentioned anionic polymerization can be used, and the concentration of the monomer in the reaction solution is the same as in the case of anionic polymerization. . Furthermore, the reaction pressure in coordination polymerization is the same as that in the case of anionic polymerization, and it is desirable that the raw material used for the reaction substantially removes reaction inhibitors such as water, oxygen, carbon dioxide, and protic compounds.
As a conjugated diene polymer having a polymerization active terminal obtained by coordination polymerization using a polymerization initiator containing this lanthanum series rare earth element compound, a homopolymer obtained by polymerizing one kind of conjugated diene compound, or A copolymer obtained by polymerization using two or more kinds is preferred. The conjugated diene compound is selected from isoprene, 1,3-butadiene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene and 1,3-hexadiene. It is preferable that the compound is one or more compounds, and among these, isoprene, 1,3-butadiene and 2,3-dimethyl-1,3-butadiene are more preferable, and isoprene and 1,3-butadiene are particularly preferable. .
Also in coordination polymerization, it is possible to copolymerize one or more conjugated diene compounds and an aromatic vinyl compound as necessary. In this case, the aromatic vinyl compound is selected from styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene and 2,4,6-trimethylstyrene. One or more selected compounds are preferable, and styrene is particularly preferable.

  When the thermoreversible crosslinkable conjugated diene polymer according to the present invention is produced by coordination polymerization, the vinyl bond content of the conjugated diene compound portion of the polymer is preferably 1 mol% or less. In coordination polymerization, by increasing the cis-1,4 bond content and lowering the vinyl bond content, the stretched crystallinity of the polymer is increased, and the fracture resistance and low exothermicity are further increased. This is for improvement. Here, the measuring method of vinyl bond content of 2 mol% or less is based on the Fourier transform infrared spectroscopy described in Unexamined-Japanese-Patent No. 2008-291096.

  The kind of the conjugated diene polymer as the thermoreversible crosslinkable conjugated diene polymer according to the present invention includes polybutadiene rubber (hereinafter sometimes abbreviated as “BR”), synthetic polyisoprene rubber (hereinafter referred to as “IR”). ), Butadiene-isoprene copolymer rubber (hereinafter sometimes abbreviated as “BIR”), styrene-butadiene copolymer rubber (hereinafter abbreviated as “SBR”). Styrene-isoprene copolymer rubber (hereinafter sometimes abbreviated as “SIR”) and the like are preferable examples, and among these, BR and IR are particularly preferable.

In order to set the crosslinking initiation temperature to 100 ° C. or lower, at least a part of molecular chain terminals of the thermoreversible crosslinkable conjugated diene polymer according to the present invention is —COOH; —NH—C (═O) —, A functional group having an amide bond represented by at least one selected from> NC (═O) —N <and> NC (═O) —O—; an organophosphate compound residue represented by the following general formula (I) One or more functional groups selected from the group consisting of organic amine compound residues represented by the following general formula (II); and organic amine phosphate compound residues represented by the following general formula (III) (hereinafter referred to as “modifying groups”); It is preferable from the viewpoint of further improving the workability of the unvulcanized rubber composition, the fracture resistance and the low heat build-up of the vulcanized rubber composition. This thermoreversible crosslinkable conjugated diene polymer has an average value in its molecular chain from the viewpoint of further improving the workability of the unvulcanized rubber composition and the fracture resistance and low heat build-up of the vulcanized rubber composition. It is more preferable to have at least 0.5 or more of the functional groups, more preferable to have at least 0.7 or more of the functional groups as an average value, and particularly preferable to have at least one or more of the functional groups as an average value. preferable. This is because increasing the number of functional groups makes it easier for the polymers to form a network. There is no particular upper limit to the number of the functional groups that the molecular chain of the thermoreversible crosslinkable conjugated diene polymer according to the present invention has, but the functional group depends on the number of molecular chain terminals that can react with the functional group in the molecular chain. The number of is limited. Usually, since the number of molecular chain ends that can react with the functional group in the molecular chain is 1 or 2, when one functional group reacts with one molecular chain end, the thermoreversible crosslinkable conjugate according to the present invention The number of the functional groups contained in the molecular chain of the diene polymer is 2.0 or less as an average value.
The end of the molecular chain of the thermoreversible crosslinkable conjugated diene polymer according to the present invention has —COOH, the workability of the unvulcanized rubber composition and the fracture resistance of the vulcanized rubber composition This is particularly preferable from the viewpoint of further improving the low heat build-up.

In the general formula (I), R ¹ and R ² are each independently a linear or branched alkyl group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and one group. A monovalent hydrocarbon group selected from valent aromatic hydrocarbon groups having 6 to 20 carbon atoms, or a hydrogen atom.
In addition, when either R ¹ or R ² leaves the organophosphate compound residue represented by the general formula (I), an organophosphate anion is formed, and both R ¹ and R ² are represented by the general formula (I ), An organophosphate dianion is formed.

In the general formula (II), R ³ is a linear or branched alkylene group having 1 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a divalent group having 6 to 20 carbon atoms. A divalent hydrocarbon group selected from the following aromatic hydrocarbon groups, or a single bond. Here, the single bond means that the N atom of the organic amine compound residue represented by the general formula (II) is directly bonded to the molecular chain terminal of the thermoreversible crosslinkable conjugated diene polymer with a single bond. Say.
R ⁴ and R ⁵ are each independently a linear or branched monovalent alkyl group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and 6 to 20 carbon atoms. It is a monovalent hydrocarbon group selected from monovalent aromatic hydrocarbon groups or a hydrogen atom, and at least one of R ⁴ and R ⁵ is a hydrogen atom.

In the general formula (III), R ⁷ represents a linear or branched alkylene group having 1 to 20 carbon atoms, a divalent alicyclic hydrocarbon group and a divalent C6-20 having 3 to 20 carbon atoms It is a divalent hydrocarbon group selected from the following aromatic hydrocarbon groups. R ⁶ , R ⁸ and R ⁹ are each independently a linear or branched monovalent alkyl group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms and 6 carbon atoms. A monovalent hydrocarbon group selected from -20 monovalent aromatic hydrocarbon groups or a hydrogen atom, and at least one of R ⁸ and R ⁹ is a hydrogen atom.

Examples of the functional group having an amide bond represented by at least one selected from the above -NH-C (= O)-,> NC (= O) -N <and> NC (= O) -O- include R ^{a -NH-C (= O)} -, R b -NH-C (= O) -NR c - and ^{R d -NH-C (= O} ) -O- least one amide bond represented by selected from It is preferable that it is a functional group which has.
Here, R ^a , R ^b , R ^c and R ^d are each independently a monovalent hydrocarbon group having 1 to 30 carbon atoms selected from an alkyl group, an aralkyl group and an alkylaryl group, or a hydrogen atom. .

Examples of the modifier for bonding —COOH to the molecular chain terminal of the thermoreversible crosslinkable conjugated diene polymer include carbon dioxide, and —NH— at the molecular chain terminal of the thermoreversible crosslinkable conjugated diene polymer. Examples of the modifier for bonding C (= O)-include phenyl isocyanate, and for bonding> NC (= O) -N <to the molecular chain terminal of the thermoreversible crosslinkable conjugated diene polymer. Examples of the modifier include benzylidene aniline and phenyl isocyanate.
In addition, examples of the modifying agent for binding the organophosphate compound residue represented by the general formula (I) to the molecular chain terminal of the thermoreversible crosslinkable conjugated diene polymer include diethyl chlorophosphonate, An example of a modifier for binding an organic quaternary ammonium compound residue (cation) to the molecular chain terminal of the thermoreversible crosslinkable conjugated diene polymer is anhydrous betaine.

In order for the molecular chain terminal of the thermoreversible crosslinkable conjugated diene polymer to have —COOH, it is preferable to form —COOH by reacting the molecular chain terminal with carbon dioxide.
The molecular chain terminal of the thermoreversible crosslinkable conjugated diene polymer is at least selected from —NH—C (═O) —,> NC (═O) —N <and> NC (═O) —O—. In order to have a functional group having an amide bond represented by one kind, a method in which the molecular chain terminal (terminal anion group of the living polymer) is modified with an isocyanate, the molecular chain terminal is reacted with an imine compound and then isocyanate. Examples of the modification method include treating with a natto.
Here, as the isocyanate compound, for example, phenyl isocyanate; 4,4′-methylenebisphenyl isocyanate (MDI); 2,4-toluylene diisocyanate (2,4-TDI); 2,6 toluylene diisocyanate Nert (2,6-TDI), crude methylene diisocyanate (crude MDI), diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, p-phenylene diisocyanate, xylylene diisocyanate; , 2,4-triisocyanate; naphthalene-1,2,5,7-tetraisocyanate; aromatic isocyanates such as naphthalene-1,3,7-triisocyanate, hexamethylene diisocyanate, methylcyclohexane Diisocyanate Examples thereof include aliphatic isocyanates such as nates.

  Examples of the imine compound used in the modification method in which the molecular chain terminal is reacted with an imine compound and then treated with an isocyanate include, for example, ethaneimine, benzylimine, acetoneimine, acetophenoneimine, benzylideneaniline, benzylideneethylamine; Amidine, acetamidine, 1-phenylbenzoamidine, 1-methylbenzamidine, 1-phenylacetamidine, 1-benzoylbenzoamidine, 1-acetylbenzoamidine, 1-benzoylacetamidine, N-amidinobenzamide, N-amidinoacetamide N- (N-phenylamidino) benzamide, N- (N-phenylamidino) acetamide, N- (N-phenylamidino) stearamide, N- (N-methylamidino) benzamide. Amidine compounds of: benzohydrazidoimine, acetohydrazidoimine, 2-phenylbenzohydrazidoimine, 2-methylbenzohydrazidoimine, 2-phenylacetohydrazidoimine, 2-benzoylbenzohydrazidoimine, 2-acetylbenzohydrazidoimine, 2- Examples thereof include hydrazide imine compounds such as benzoylacetohydrazidoimine and 2-amidinobenzohydrazidoimine. Among the above, compounds having an imino group with a> C═NH— structure are preferable.

  In the modification reaction in the present invention, the conjugated diene polymer having an active end to be used is preferably one in which at least 10% of the polymer chains have a living property. Accordingly, -COOH, -NH-C (= O)-,> NC (=), N <, and> NC (= O) -O-, the organophosphate compound residue represented by the general formula (I) One or more functional groups selected from the group consisting of the organic quaternary ammonium compound residue represented by the general formula (II) and the organic quaternary ammonium phosphate compound residue represented by the general formula (III), The modification reaction to be bonded to the molecular chain terminal of the thermoreversible crosslinkable conjugated diene polymer according to the present invention can be suitably performed in both anionic polymerization and coordination polymerization.

  The number average molecular weight in terms of polystyrene of the thermoreversible crosslinkable conjugated diene polymer according to the present invention is preferably 50,000 to 400,000. By controlling the molecular weight, the workability of the unvulcanized rubber composition at high temperatures is further improved, and the high puncture resistance and low heat build-up at the use temperature (such as room temperature) of the vulcanized rubber composition are further improved. This is to make it easier. In this respect, the polystyrene-reduced number average molecular weight of the thermoreversible crosslinkable conjugated diene polymer is more preferably 100,000 to 300,000. The number average molecular weight in terms of polystyrene is a value calculated as a standard polystyrene equivalent using a differential refractometer as a detector using gel permeation chromatography (GPC: gel permeation chromatography), and the sample concentration used. Was 4 mg / 5 ml THF solution.

The rubber component of the rubber composition of the present invention preferably contains 20-80% by mass of thermoreversible crosslinkable conjugated diene polymer and 80-20% by mass of natural rubber. Further, the thermoreversible crosslinkable conjugated diene polymer is included in an amount of 30 to 70% by mass, the natural rubber is preferably included in an amount of 70 to 30% by mass, the thermoreversible crosslinkable conjugated diene polymer is included in an amount of 40 to 60% by mass, More preferably, it contains 60-40% by mass of natural rubber. When the thermoreversible crosslinkable conjugated diene polymer is contained in an amount of 20 to 80% by mass and the natural rubber is contained in an amount of 80 to 20% by mass, a polymer network of the thermoreversible crosslinkable conjugated diene polymer is suitably formed, and the tire is normally used. This is because the fracture resistance and low heat build-up of the rubber composition at temperature are further improved.
The natural rubber blended into the rubber composition of the present invention as desired may be an unmodified natural rubber or a modified natural rubber. As the modified natural rubber, for example, an epoxy-modified natural rubber is used.

Among the rubber components of the rubber composition of the present invention, as other rubber components other than the thermally reversible crosslinkable conjugated diene polymer and the natural rubber blended as desired, other synthetic isoprene rubber, other butadiene rubber, styrene- Butadiene rubber, ethylene-α-olefin copolymer rubber, ethylene-α-olefin-diene copolymer rubber, acrylonitrile-butadiene rubber, chlorobrene rubber, halogenated butyl rubber, and copolymer of styrene and isobutylene having halogenated methyl groups At least one selected from the above is preferably used.
One type of thermoreversible crosslinkable conjugated diene polymer according to the present invention may be used, or two or more types may be used in combination.
In addition, other rubber components other than the thermoreversible crosslinkable conjugated diene polymer and natural rubber may be used, or two or more kinds may be used in combination.

The rubber composition of the present invention comprises a vulcanizing agent selected from at least one selected from sulfur, sulfur compounds, inorganic metal compounds, polyamines, and organic peroxides as required. Here, as the sulfur, various powdered sulfur such as petroleum-derived, volcanic-derived, mineral-derived, precipitated sulfur, colloidal sulfur, insoluble sulfur 000 and the like are used. Examples of the sulfur compound include morpholine disulfide, sulfur chloride, polymer polysulfide, tetramethylthiuram disulfide, selenium dimethyldithiocarbamate, and 2- (4′-morpholinodithio) benzothiazole. Examples of the inorganic metal other than sulfur include selenium (selenium) and tellurium (tellurium), and examples of the inorganic metal compound include magnesium oxide, lead monoxide (resurge), and zinc dioxide. Examples of polyamines include hexamethylene diamine, triethylene tetramine, tetraethylene pentamine, hexamethylene diamine carbamate, N, N-dicinnamylidene-1,6-hexane diamine, 4,4'-methylenebis (cyclohexylamine) carbamate. 4,4′-methylenebis (2-chloroaniline) and the like, and examples of the organic peroxide include tert-butyl hydroperoxide, cumene hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl group. Examples include mill peroxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, benzoyl peroxide and the like.
It is preferable that 0.3 to 15 parts by mass of the vulcanizing agent is added to 100 parts by mass of the rubber component containing the thermoreversible crosslinkable conjugated diene polymer according to the present invention, and 0.5 to 10 parts by mass is added. It is more preferable.
One vulcanizing agent according to the present invention may be used, or two or more vulcanizing agents may be used in combination.

If necessary, the rubber composition of the present invention further contains 5 to 100 parts by mass of carbon black as a filler with respect to 100 parts by mass of the rubber component containing the thermoreversible crosslinkable conjugated diene polymer according to the present invention. You may mix | blend. By blending 5 to 100 parts by mass of carbon black, the fracture resistance of the vulcanized rubber composition can be further improved. Moreover, by mix | blending 100 mass parts or less, formation of the polymer network of a thermoreversible crosslinkable conjugated diene type polymer can be prevented. From this viewpoint, it is more preferable to blend carbon black in an amount of 80 parts by mass or less, still more preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less.
The nitrogen adsorption specific surface area (N ₂ SA) of carbon black used as a filler in the present invention is preferably 20 to ²⁰⁰ m ² / g. This is because if it is 20 m ² / g or more, the reinforcing property of the rubber composition can be suitably secured, and if it is 200 m ² / g or less, low heat build-up can be improved.
Specific examples include SRF, GPF, FEF, HAF, N326, N339, N347, N351, IISAF, ISAF, and SAF.
One type of carbon black may be used, or two or more types may be used in combination.

In the rubber composition of the present invention, various chemicals usually used in the rubber industry, for example, inorganic fillers such as silica, vulcanization accelerators, process oils, and the like, as long as the object of the present invention is not impaired. Anti-aging agent, scorch inhibitor, zinc white, stearic acid and the like can be blended.
Further, the rubber composition of the present invention is obtained by kneading using a kneader such as an open kneader such as a roll, a closed kneader such as a Banbury mixer, and vulcanized after molding. Applicable to various rubber products. For example, tire tires such as tire treads, under treads, carcass, sidewalls, side reinforcing rubbers, and bead parts (particularly bead fillers), anti-vibration rubber, fenders, belts, hoses and other industrial products In particular, it is suitably used as a rubber composition for treads of low fuel consumption tires, large tires, and high performance tires, which have an excellent balance of low heat generation, wear resistance, and fracture resistance. The tire of the present invention is obtained. That is, it is preferable that one of the members of the tire of the present invention using the rubber composition of the present invention is a tread.

  The tire of the present invention has low rolling resistance and excellent fuel efficiency, as well as excellent fracture characteristics and wear resistance. In addition, as gas with which the tire of the present invention is filled, normal or air with a changed oxygen partial pressure, or an inert gas such as nitrogen is exemplified. The rubber composition for a tread according to the present invention is extruded into, for example, a tread member, and is pasted and molded by a usual method on a tire molding machine to form a raw tire. The green tire is heated and pressed in a vulcanizer to obtain the tire of the present invention.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.
Crosslink cleavage initiation temperature (° C.) of conjugated diene polymer, vinyl bond content (mol%), number average molecular weight (Mn), number of modified groups per polymer molecular chain, unvulcanized rubber composition The Mooney viscosity (ML _{1 + 4} ) and the fracture resistance index and low exothermic index (tan δ index) of the vulcanized rubber composition were measured by the following methods.

1. Cross-linking initiation temperature (℃)
Using a dynamic shear viscoelasticity tester {Rheometrics Scientific Viscoelasticity Tester (ARES)}, dynamic strain is 1%, frequency is 15 Hz and data is in increments of 1 ° C in the range of 30 ° C to 150 ° C. Then, the temperature dispersion of the dynamic loss elastic modulus G ″ was measured, and the decrease start temperature of G ″ was set as the crosslinking initiation temperature.
2. Vinyl bond content (mol%)
The vinyl bond content exceeding 2 mol% is measured based on the Morero method by infrared absorption spectrum, and the vinyl bond content of 2 mol% or less is measured by Fourier transform infrared spectroscopy described in JP-A-2008-291096. Measured based on the law.

3. Polystyrene equivalent number average molecular weight (Mn)
Gel permeation chromatography (trade name “HLC-8120GPC”, manufactured by Tosoh Corporation) was used, a differential refractometer was used as a detector, and measurement was performed under the following conditions to calculate a standard polystyrene equivalent value.
Column: Trade name “GMHXL” (manufactured by Tosoh Corporation) 2 Column temperature: 40 ° C.
Mobile phase: Tetrahydrofuran Flow rate: 1.0 ml / min
Sample concentration: 4mg / 5ml
4). Number of modifying groups per polymer molecular chain After staining with a fluorescent labeling agent, it was measured by fluorescence detection.

5. Mooney viscosity of unvulcanized rubber composition (ML _{1 + 4} )
In accordance with JIS K6300-1: 2013, measurement was performed using an L rotor under conditions of preheating for 1 minute, rotor operating time of 4 minutes, and temperature of 130 ° C. The value was obtained by the following formula, assuming Comparative Example 1, 5, 8, or 11 as 100. The lower the value, the better the workability of the unvulcanized rubber composition.
Mooney viscosity index = {(Mooney viscosity of test sample) / (Mooney viscosity of Comparative Example 1, 5, 8, or 11)} × 100
6). Fracture resistance index According to JIS K6251: 2010, vulcanized at 145 ° C. for 30 minutes, a dumbbell-shaped No. 3 vulcanized rubber composition sample was subjected to a tensile test at 100 ° C., and the tensile strength at the time of cutting was measured. The value was obtained by the following formula, assuming Comparative Example 1, 5, 8, or 11 as 100. The higher the value, the better the fracture resistance.
Fracture resistance index = {(tensile strength at break of test sample) / (tensile strength at break of Comparative Example 1, 5, 8, or 11)} × 100
7). Low exothermic index (tan δ index)
Using a dynamic spectrometer manufactured by Ueshima Seisakusho, tan δ was measured under the conditions of an initial tensile strain of 10%, a tensile dynamic strain of 1%, a frequency of 10 Hz, and 50 ° C., and Comparative Example 1, 5, 8 or 11 was taken as 100. It calculated | required with the following formula | equation. The lower the value, the lower the heat generation.
Low exothermic index = {(tan δ of test sample) / (tan δ of Comparative Example 1, 5, 8 or 11)} × 100

Production Example 1 Production of Modified BR-1 Under nitrogen, 477 g of cyclohexane, 65 g of 1,3-butadiene, and 0.053 mmol of 2,2-ditetrahydrofurylpropane were injected into a 2 L pressure-resistant glass bottle substituted with nitrogen as a cyclohexane solution. After adding 0.9 mmol of n-butyllithium (BuLi) to the mixture, polymerization was carried out in a 50 ° C. warm water bath equipped with a stirrer for 3 hours. The reaction conversion of 1,3-butadiene was almost 100%. Next, this polymer solution was kept at a temperature of 50 ° C., 0.9 mmol of Lewis base N, N, N ′, N′-tetramethylethylenediamine was added, and carbon dioxide was added at a gauge pressure of 2 kg · cm ³ and 10 mmol. The reaction was carried out for a minute. Thereafter, a methanol solution containing 0.5 g of 2,6-di-tert-butyl-p-cresol was added to terminate the polymerization, and then the solvent was removed by steam stripping, followed by drying with a roll at 110 ° C. -1 was obtained. The number average molecular weight (Mn) before modification is 252,000, the vinyl content is 20 mol%, the crosslinking initiation temperature is 61 ° C., and the number of modifying groups per polymer molecular chain is 0.8.

Production Examples 2 to 4 and 8 Production of Modified BR-2 to 5 First, 1 mol of 1,3- (diisopropenyl) benzene was added to a sufficiently dehydrated and purified cyclohexane solvent, followed by 2 mol of triethylamine, sec- 2 mol of butyl lithium was sequentially added and stirred at 50 ° C. for 2 hours to prepare dilithium polymerization initiators used in Production Examples 2 to 4 and 8.
Next, as shown in Table 2, n-butyllithium was changed to dilithium polymerization initiator, and 1,3-butadiene amount (g), dilithium polymerization initiator amount (mmol), 2,2-ditetrahydrofuryl. Modified BR-2 to 5 were produced in the same manner as in Production Example 1 except that the amount of propane (mmol) and the amount of N, N, N ′, N′-tetramethylethylenediamine (mmol) were changed. The gauge pressure (kg / cm ³ ), feed time (minutes), and reaction temperature (° C.) of carbon dioxide as a modifier are the same as in Production Example 1.
Table 2 shows the number average molecular weight (Mn) of each modified BR before modification, the vinyl content, the crosslinking initiation temperature, and the number of modified groups per polymer molecular chain.

Production Examples 5 to 7 Production of Unmodified BR-1 to 3 As shown in Table 2, the amount of 1,3-butadiene (g), the amount of n-butyllithium (mmol), and the amount of 2,2-ditetrahydrofurylpropane (Mmol) was changed, N, N, N ′, N′-tetramethylethylenediamine was not added, and carbon dioxide was not fed. Manufactured. The number average molecular weight (Mn) and vinyl content of each unmodified BR are shown in Table 2.

Production Example 9 Production of Modified IR-1 A nitrogen-substituted 2 L pressure-resistant glass bottle was charged with 477 g of cyclohexane, 65 g of isoprene, and 0.9 mmol of n-butyllithium (BuLi) under nitrogen, and then equipped with a stirrer. Polymerization was carried out in a 50 ° C. warm water bath for 3 hours. The reaction conversion rate of isoprene was almost 100%. Next, this polymer solution was kept at a temperature of 50 ° C., 0.9 mmol of Lewis base N, N, N ′, N′-tetramethylethylenediamine was added, and carbon dioxide was added at a gauge pressure of 2 kg · cm ³ for 10 minutes. Feed and react. Thereafter, a methanol solution containing 0.5 g of 2,6-di-tert-butyl-p-cresol was added to terminate the polymerization, and then the solvent was removed by steam stripping, followed by drying with a roll at 110 ° C. -1 was obtained. The number average molecular weight (Mn) before modification is 249,000, the vinyl content is 6 mol%, the crosslinking initiation temperature is 65 ° C., and the number of modifying groups per polymer molecular chain is 0.8.

Production Examples 10 to 13 Production of Modified IR-2 to 5 First, 1 mol of 1,3- (diisopropenyl) benzene was added to a sufficiently dehydrated and purified cyclohexane solvent, followed by 2 mol of triethylamine, sec-butyllithium. 2 mol was added in order, and it stirred at 50 degreeC for 2 hours, and prepared the dilithium polymerization initiator used for manufacture examples 10-13.
Next, as shown in Table 3, n-butyl lithium was changed to a dilithium polymerization initiator, and isoprene amount (g), dilithium polymerization initiator amount (mmol), 2,2-ditetrahydrofurylpropane amount (mmol). ) And N, N, N ′, N′-tetramethylethylenediamine amount (mmol) were changed to produce modified IR-2 to 5 in the same manner as in Production Example 9. The gauge pressure (kg / cm ³ ), feed time (minutes), and reaction temperature (° C.) of carbon dioxide as a modifier are the same as in Production Example 9. Table 3 shows the number average molecular weight (Mn) of each modified IR before modification, the vinyl content, the crosslinking initiation temperature, and the number of modified groups per polymer molecular chain.

Production Examples 14 to 16 Production of Unmodified IR-1 to 3 As shown in Table 3, the amount of isoprene (g), the amount of n-butyllithium (mmol), and the amount of 2,2-ditetrahydrofurylpropane (mmol) Non-modified IR-1 to 3 were produced in the same manner as in Production Example 9, except that N, N, N ′, N′-tetramethylethylenediamine was not added and carbon dioxide was not fed. The number average molecular weight (Mn) and vinyl content of each unmodified IR are shown in Table 3.

Production Example 17 Production of Modified BR-6 In a nitrogen-substituted 200 mL glass bottle, in a nitrogen atmosphere, 4.76 g of 1,3-butadiene, a cyclohexane solution of neodymium versatate (0.03 mmol) as a catalyst component, methylaluminoxane (hereinafter referred to as “aluminum oxide”) A toluene solution (also referred to as “MAO”) (25.5 mmol) and diisobutylaluminum hydride (hereinafter also referred to as “DIBAH”) (6.3 mmol) were charged and reacted at 30 ° C. for 2 minutes. Further, a toluene solution of diethylaluminum chloride (1.2 mmol) was reacted and aged at 30 ° C. for 15 minutes in this glass bottle to prepare a catalyst composition in advance.
A nitrogen-substituted 2 L pressure-resistant glass bottle was charged with 477 g of cyclohexane and 65 g of butadiene under nitrogen, 0.0325 mmol of the catalyst composition prepared above was charged in Nd amount, and polymerization was performed at 0 ° C. for 3 hours. The reaction conversion of 1,3-butadiene was almost 100%.
Next, with this polymer solution kept at room temperature (25 ° C.), carbon dioxide was fed at a gauge pressure of 2 kg · cm ³ for 10 minutes to react. Thereafter, a methanol solution containing 0.5 g of 2,6-di-tert-butyl-p-cresol was added to terminate the polymerization, and then the solvent was removed by steam stripping, followed by drying with a roll at 110 ° C. -6 was obtained. The number average molecular weight (Mn) before modification is 253,000, the vinyl content is 0.15 mol%, the crosslinking initiation temperature is 61 ° C., and the number of modifying groups per polymer molecular chain Was 0.9.

Production Example 18 Production of Modified BR-7 As shown in Table 4, modified BR-7 was produced in the same manner as in Production Example 17, except that the amount of catalyst input was changed. Table 4 shows the number average molecular weight (Mn) of the modified BR-7 before modification, the vinyl content, the crosslinking initiation temperature, and the number of modified groups per polymer molecular chain.

Production Examples 19 to 21 Production of Unmodified BR-4 to 6 As shown in Table 4, the amount of catalyst input was changed and carbon dioxide was not fed. 4-6 were manufactured. Table 4 shows the number average molecular weight (Mn) and vinyl content of each unmodified BR.

Production Example 22 Production of Modified IR-6 In a nitrogen-substituted 200 mL glass bottle, in a nitrogen atmosphere, 4.76 g of isoprene, a cyclohexane solution of neodymium versatate (0.03 mmol) as a catalyst component, methylaluminoxane (hereinafter referred to as “MAO”) (25.5 mmol) in toluene and diisobutylaluminum hydride (hereinafter also referred to as “DIBAH”) (6.3 mmol) were charged and reacted at 30 ° C. for 2 minutes. Further, a toluene solution of diethylaluminum chloride (1.2 mmol) was reacted and aged at 30 ° C. for 15 minutes in this glass bottle to prepare a catalyst composition in advance.
A nitrogen-substituted 2 L pressure-resistant glass bottle was charged with 477 g of cyclohexane and 65 g of isoprene under nitrogen, 0.0325 mmol of Nd amount of the catalyst composition prepared above was charged, and polymerization was performed at 0 ° C. for 3 hours. The reaction conversion of 1,3-butadiene was almost 100%.
Next, with this polymer solution kept at room temperature (25 ° C.), carbon dioxide was fed at a gauge pressure of 2 kg · cm ³ for 10 minutes to react. Thereafter, a methanol solution containing 0.5 g of 2,6-di-tert-butyl-p-cresol was added to terminate the polymerization, and then the solvent was removed by steam stripping, followed by drying with a roll at 110 ° C. -7 was obtained. The number average molecular weight (Mn) before modification is 253,000, the vinyl content is 0.15 mol%, the crosslinking initiation temperature is 65 ° C., and the number of modified groups per polymer molecular chain is The number was 0.9.

Production Example 23 Production of Modified IR-7 As shown in Table 5, modified IR-7 was produced in the same manner as in Production Example 22 except that the amount of catalyst input was changed. Table 5 shows the number average molecular weight (Mn) of the modified IR-7 before modification, the vinyl content, the crosslinking initiation temperature, and the number of modified groups per polymer molecular chain.

Production Examples 24-26 Production of Unmodified IR-4-6 As shown in Table 5, unmodified IR- was produced in the same manner as in Production Example 22 except that the amount of catalyst input was changed and carbon dioxide was not fed. 4-6 were manufactured. The number average molecular weight (Mn) and vinyl content of each unmodified IR are shown in Table 5.

Examples 1-13 and Comparative Examples 1-13
Using the modified BR, unmodified BR, modified IR and unmodified IR obtained in Production Examples 1 to 26, each rubber composition according to Examples 1 to 13 and Comparative Examples 1 to 13 according to the formulation shown in Table 1 A product was prepared. The Mooney viscosity index (ML _{1 + 4} ) of the obtained unvulcanized rubber composition was measured. Further, the obtained unvulcanized rubber compositions were vulcanized at 145 ° C. for 30 minutes, respectively, and the fracture resistance index was evaluated by the above method.
Next, pneumatic radial tires for passenger cars of tire sizes 225 / 45ZR17 of Examples 1 to 13 and Comparative Examples 1 to 13 using these unvulcanized rubber compositions as treads were produced by a conventional method. Samples of the vulcanized rubber composition were cut out from the tire treads of Examples 1 to 13 and Comparative Examples 1 to 13, and the low exothermic index (tan δ index) was evaluated. The results are shown in Tables 2-5.

［注］
＊１： ＲＳＳ＃１
＊２： カーボンブラックＩＳＡＦ［東海カーボン（株）製、商品名「シースト６」、窒素吸着比表面積（Ｎ₂ＳＡ）：１１８ｍ²／ｇ］
＊３： Ｎ−（１，３−ジメチルブチル）−Ｎ’−フェニル−ｐ−フェニレンジアミン、［大内新興化学工業（株）製、商品名「ノクラック６Ｃ」］
＊４：１，３−ジフェニルグアニジン、［大内新興化学工業（株）製、商品名「ノクセラーＤ」］
＊５：Ｎ−ｔｅｒｔ-ブチル−２−ベンゾチアゾリルスルフェンアミド、［三新化学工業（株）製、商品名「サンセラーＮＳ」］
＊６：ジ−２−ベンゾチアゾリルジスルフィド、［大内新興化学工業（株）製、商品名「ノクセラーＤＭ」］

[note]
* 1: RSS # 1
* 2: Carbon black ISAF [manufactured by Tokai Carbon Co., Ltd., trade name “SEAST 6”, nitrogen adsorption specific surface area (N ₂ SA): 118 m ² / g]
* 3: N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, [Ouchi Shinsei Chemical Co., Ltd., trade name “NOCRACK 6C”]
* 4: 1,3-diphenylguanidine, [Ouchi Shinsei Chemical Co., Ltd., trade name “Noxeller D”]
* 5: N-tert-butyl-2-benzothiazolylsulfenamide, [Sanshin Chemical Industry Co., Ltd., trade name “Sunseller NS”]
* 6: Di-2-benzothiazolyl disulfide [Ouchi Shinsei Chemical Co., Ltd., trade name “Noxeller DM”]

  As can be seen from Tables 2 to 5, the rubber compositions and tires of the examples of the present invention are more resistant to fracture and heat than the rubber compositions and tires of comparative examples to be compared. It turns out that it is excellent in property.

  The rubber composition of the present invention can give various tires excellent in fracture resistance and low heat buildup. The tire of the present invention using this rubber composition for treads and / or other various members includes passenger car tires (including light passenger car tires), light truck tires, light truck tires, truck and bus tires, As an off-the-road tire (a tire for construction vehicles, a tire for mining vehicles, etc.), it is particularly preferably used as a tire for passenger cars.

Claims (17)

  A rubber composition comprising a thermoreversible crosslinkable conjugated diene polymer having a crosslinking initiation temperature at 100 ° C. or lower and a vinyl bond content of a conjugated diene compound portion of 30 mol% or lower.   The rubber composition according to claim 1, comprising the thermoreversible crosslinkable conjugated diene polymer and natural rubber. At least a part of the molecular chain terminal of the thermoreversible crosslinkable conjugated diene polymer is -COOH; -NH-C (= O)-,> NC (= O) -N <and> NC (= O)- A functional group having an amide bond represented by at least one selected from O-; an organic phosphate compound residue represented by the following general formula (I); an organic amine compound residue represented by the following general formula (II); The rubber composition according to claim 1 or 2, having one or more functional groups selected from the group consisting of organic amine phosphate compound residues represented by the following general formula (III).

[In General Formula (I), R ¹ and R ² are each independently a linear or branched alkyl group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, A monovalent hydrocarbon group selected from valent aromatic hydrocarbon groups having 6 to 20 carbon atoms, or a hydrogen atom. ]

[In General Formula (II), R ³ is a linear or branched alkylene group having 1 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a divalent group having 6 to 20 carbon atoms. A divalent hydrocarbon group selected from the following aromatic hydrocarbon groups, or a single bond. R ⁴ and R ⁵ are each independently a linear or branched monovalent alkyl group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and 6 to 20 carbon atoms. It is a monovalent hydrocarbon group selected from monovalent aromatic hydrocarbon groups or a hydrogen atom, and at least one of R ⁴ and R ⁵ is a hydrogen atom. ]

[In General Formula (III), R ⁷ is a linear or branched alkylene group having 1 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a divalent group having 6 to 20 carbon atoms. It is a divalent hydrocarbon group selected from the following aromatic hydrocarbon groups. R ⁶ , R ⁸ and R ⁹ are each independently a linear or branched monovalent alkyl group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms and 6 carbon atoms. A monovalent hydrocarbon group selected from -20 monovalent aromatic hydrocarbon groups or a hydrogen atom, and at least one of R ⁸ and R ⁹ is a hydrogen atom. ]   The rubber composition according to claim 3, wherein at least a part of molecular chain terminals of the thermoreversible crosslinkable conjugated diene polymer has —COOH.   The rubber composition according to claim 3 or 4, wherein the thermoreversible crosslinkable conjugated diene polymer has at least one or more functional groups as an average value in the molecular chain.   The thermoreversible crosslinkable conjugated diene polymer is anionic polymerization of one or more conjugated diene compounds or one or more conjugated diene compounds and an aromatic vinyl compound using an organic alkali metal compound or an organic alkaline earth metal as a polymerization initiator. The rubber composition according to any one of claims 1 to 5, wherein the rubber composition is obtained.   The thermoreversible crosslinkable conjugated diene polymer uses one or more conjugated diene compounds, or one or more conjugated diene compounds and an aromatic vinyl compound using a polymerization initiator containing a lanthanum series rare earth metal compound. The rubber composition according to any one of claims 1 to 5, wherein the rubber composition is obtained.   The rubber composition according to any one of claims 1 to 7, wherein the thermoreversible crosslinkable conjugated diene polymer is obtained by reacting the molecular chain terminal with carbon dioxide.   The rubber composition according to any one of claims 1 to 8, wherein the thermoreversible crosslinkable conjugated diene polymer has a polystyrene-equivalent number average molecular weight of 50,000 to 400,000.   The rubber composition according to claim 9, wherein the thermoreversible crosslinkable conjugated diene polymer has a number average molecular weight in terms of polystyrene of 100,000 to 300,000.   The rubber composition according to any one of claims 7 to 10, wherein a vinyl bond content of a conjugated diene compound portion of the thermoreversible crosslinkable conjugated diene polymer is 1 mol% or less.   The conjugated diene compound is selected from isoprene, 1,3-butadiene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene and 1,3-hexadiene. The rubber composition according to any one of claims 1 to 11, which is one or more compounds.   The aromatic vinyl compound is selected from styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, and 2,4,6-trimethylstyrene. The rubber composition according to any one of claims 6 to 12, which is a compound of at least one species.   Furthermore, the rubber composition of any one of Claims 1-13 formed by mix | blending 1 or more types of vulcanizing agents chosen from sulfur, a sulfur compound, an inorganic metal compound, polyamines, and an organic peroxide.   Furthermore, the rubber composition of any one of Claims 1-14 formed by mix | blending 5-100 mass parts of carbon black with respect to 100 mass parts of rubber components.   A tire comprising the rubber composition according to any one of claims 1 to 15 as one or more members.   The tire according to claim 16, wherein one of the members is a tread.