Modified conjugated diene polymer, rubber composition, cross-linked rubber product, and method for producing tire

Abstract

The present invention provides a method for producing a modified conjugated diene polymer, which can produce a modified conjugated diene polymer having good fuel economy with high productivity. [Solution] A method for producing a modified conjugated diene polymer includes a first step of polymerizing a monomer containing a conjugated diene 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 reacting the conjugated diene polymer chain having an active end with a polyorganosiloxane represented by the following general formula (1) by continuously adding the polyorganosiloxane to the conjugated diene polymer chain having an active end over a period of 2 to 60 minutes or by adding the polyorganosiloxane in multiple divided portions: TIFF0007647990000015.tif33158

Description

[Technical field]

[0001] The present invention relates to a modified conjugated diene-based polymer, a rubber composition, a cross-linked rubber product, and a method for producing a tire. [Background technology]

[0002] In recent years, with the growing interest in environmental issues, polymers used in automobile tires are required to have excellent fuel economy characteristics. Tires obtained using a rubber composition in which a conjugated diene polymer is blended with silica as a filler have improved low heat generation properties compared to tires obtained using a rubber composition in which conventionally used carbon black is blended, and therefore can be tires with even better fuel economy characteristics.

[0003] As a conjugated diene polymer for providing such tires, Patent Document 1 proposes a modified conjugated diene polymer obtained by modifying a conjugated diene polymer chain with polyorganosiloxane. According to the technology of Patent Document 1, the affinity with silica is improved by introducing a modified structure with polyorganosiloxane, thereby making it possible to improve fuel efficiency characteristics. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2003 / 102053 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, from the viewpoint of responding to recent environmental problems, there is a demand for producing modified conjugated diene-based polymers modified with polyorganosiloxanes with improved productivity.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a modified conjugated diene polymer having good fuel economy, with high productivity. [Means for solving the problem]

[0007] The present inventors have conducted studies to achieve the above object, and have found that when reacting a specific polyorganosiloxane with a conjugated diene polymer chain having an active terminal, such a polyorganosiloxane can be added continuously over a period of 2 to 60 minutes or added in multiple portions, thereby producing a modified conjugated diene polymer having good fuel economy with high productivity, and have completed the present invention.

[0008] That is, the present invention provides the following [1] to [8]. [1] A first step of polymerizing a monomer including a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene polymer chain having an active terminal; The method for producing a modified conjugated diene polymer includes a second step of reacting the conjugated diene polymer chain having an active end with the polyorganosiloxane represented by the following general formula (1) by continuously adding the polyorganosiloxane to the conjugated diene polymer chain having an active end over a period of 2 to 60 minutes or by adding the polyorganosiloxane in multiple portions: [ka] (In the above general formula (1), R 1 ~R 8 is a hydrocarbon group having 1 to 20 carbon atoms, and these may be the same or different. X 1 and X 4 is a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a polar functional group having an atom of Group 15 or Group 16 of the periodic table, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may have the polar functional group or a halogen atom, and these may be the same or different. X 2is a polar functional group having an atom of Group 15 or 16 of the periodic table, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may have the polar functional group or a halogen atom, and X 2 When there are multiple X's, they may be the same or different. 3 is a group containing 2 to 20 repeating alkylene glycol units, X 3 A part of X may be a group derived from a group containing 2 to 20 repeating units of alkylene glycol; 3 When there are a plurality of, they may be the same or different. m is an integer of 1 to 200, n is an integer of 0 to 200, and k is an integer of 0 to 200.) [2] The method for producing a modified conjugated diene-based polymer according to [1], wherein the polar functional group having an atom of Group 16 of the periodic table is a polar functional group having an oxygen atom. [3] X 1 and X 4 is a hydrocarbon group having 1 to 20 carbon atoms, 2 The method for producing a modified conjugated diene-based polymer according to [1] or [2], wherein R is a hydrocarbon group having 1 to 20 carbon atoms which may have an alkoxy group or an epoxy group. [4] The method for producing a modified conjugated diene polymer according to any one of [1] to [3], wherein the modified conjugated diene polymer contains an isoprene-containing block containing 80 to 100% by weight of isoprene units. [5] The method for producing a modified conjugated diene-based polymer according to any one of [1] to [4], wherein a total of 0.5 mol to 5.0 mol of a polar compound is added per 1 mol of the polymerization initiator before the second step. [6] A method for producing a rubber composition, comprising obtaining a modified conjugated diene polymer by the production method according to any one of [1] to [5], and adding silica to the modified conjugated diene polymer. [7] The method for producing a rubber composition according to [6], further comprising adding a crosslinking agent. [8] A method for producing a cross-linked rubber product, comprising obtaining a rubber composition by the method according to [6] or [7] and cross-linking the rubber composition. [9] A method for producing a tire, comprising obtaining a rubber composition by the method for producing a rubber composition according to the method of producing a rubber composition according to [6] or [7], and crosslinking the rubber composition to produce a tire comprising a crosslinked rubber product of the rubber composition. Effect of the Invention

[0009] According to the present invention, it is possible to provide a method for producing a modified conjugated diene polymer, which can produce a modified conjugated diene polymer having good fuel economy with high productivity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <Method of producing modified conjugated diene polymer> The method for producing a modified conjugated diene polymer of the present invention includes a first step of polymerizing a monomer containing a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene polymer chain having an active terminal; The method includes a second step of reacting the conjugated diene polymer chain having an active terminal with the polyorganosiloxane represented by general formula (1) described later, by continuously adding the polyorganosiloxane to the conjugated diene polymer chain having an active terminal over a period of 2 to 60 minutes or by adding the polyorganosiloxane in multiple divided portions.

[0011] <1st process> The first step of the production method of the present invention is a step of polymerizing a monomer containing a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene polymer chain having an active end.

[0012] In the first step of the production method of the present invention, the conjugated diene compound used as a monomer to obtain a conjugated diene polymer chain having an active terminal is not particularly limited, but examples thereof include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, and 3-butyl-1,3-octadiene. Among these, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred. These conjugated diene compounds may be used alone or in combination of two or more.

[0013] In addition, in the first step of the production method of the present invention, an aromatic vinyl compound may be used together with the conjugated diene compound as a monomer used for polymerization. Examples of aromatic vinyl compounds used as monomers include styrene, methylstyrene, ethylstyrene, t-butylstyrene, α-methylstyrene, α-methyl-p-methylstyrene, chlorostyrene, bromostyrene, methoxystyrene, dimethylaminomethylstyrene, dimethylaminoethylstyrene, diethylaminomethylstyrene, diethylaminoethylstyrene, cyanoethylstyrene, and vinylnaphthalene. Among these, styrene is preferred. The conjugated diene polymer chain having an active end obtained in the first step of the production method of the present invention preferably contains 50 to 100% by weight of conjugated diene monomer units, more preferably contains 52 to 98% by weight, and particularly preferably contains 55 to 84% by weight, and preferably contains 0 to 50% by weight of aromatic vinyl monomer units, more preferably contains 2 to 48% by weight, and particularly preferably contains 16 to 45% by weight.

[0014] Furthermore, in the first step of the production method of the present invention, a compound copolymerizable with the conjugated diene compound other than the aromatic vinyl compound may be used together with the conjugated diene compound. Examples of such compounds copolymerizable with the conjugated diene compound include linear olefin compounds such as ethylene, propylene, and 1-butene; cyclic olefin compounds such as cyclopentene and 2-norbornene; non-conjugated diene compounds such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene; (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate; other (meth)acrylic acid derivatives such as (meth)acrylonitrile and (meth)acrylamide; and the like. The compounds copolymerizable with these conjugated diene compounds are preferably 10% by weight or less, more preferably 5% by weight or less, as monomer units, in the conjugated diene polymer chain having an active end obtained in the first step of the production method of the present invention.

[0015] The inert solvent used in the polymerization is not particularly limited as long as it is one that is usually used in solution polymerization and does not inhibit the polymerization reaction. Specific examples of the inert solvent include chain aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; and ether compounds such as tetrahydrofuran and diethyl ether. These inert solvents may be used alone or in combination of two or more. The amount of the inert solvent used is not particularly limited, but is an amount that gives a monomer concentration of, for example, 1 to 50% by weight, and preferably 10 to 40% by weight.

[0016] The polymerization initiator used in the polymerization is not particularly limited as long as it can polymerize a monomer containing a conjugated diene compound to give a conjugated diene polymer chain having an active end. Specific examples of the polymerization initiator include polymerization initiators using an organic alkali metal compound, an organic alkaline earth metal compound, and a lanthanum series metal compound as a main catalyst. Examples of the organic alkali metal compound include organic monolithium compounds such as n-butyl lithium, sec-butyl lithium, t-butyl lithium, hexyl lithium, phenyl lithium, and stilbene lithium; organic polyvalent lithium compounds such as dilithiomethane, 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, and 1,3,5-tris(lithiomethyl)benzene; organic sodium compounds such as sodium naphthalene; and organic potassium compounds such as potassium naphthalene. Examples of organic alkaline earth metal compounds include di-n-butyl magnesium, di-n-hexyl magnesium, diethoxy calcium, calcium distearate, di-t-butoxy strontium, diethoxy barium, diisopropoxy barium, diethylmercapto barium, di-t-butoxy barium, diphenoxy barium, diethylamino barium, barium distearate, diketyl barium, etc. Examples of polymerization initiators using a lanthanum series metal compound as a main catalyst include polymerization initiators using a lanthanum series metal salt consisting of a lanthanum series metal such as lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, etc., a carboxylic acid, and a phosphorus-containing organic acid, etc., as a main catalyst, and a co-catalyst such as an alkyl aluminum compound, an organoaluminum hydride compound, an organoaluminum halide compound, etc. Among these polymerization initiators, the organic monolithium compounds and the organic polyvalent lithium compounds are preferably used, the organic monolithium compounds are more preferably used, and n-butyllithium is particularly preferably used. The organic alkali metal compound may be reacted in advance with a secondary amine compound such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, piperidine, hexamethyleneimine, and heptamethyleneimine to be used as an organic alkali metal amide compound. By using the organic alkali metal amide compound as a polymerization initiator, the obtained cross-linked rubber product can have better wet grip properties and wear resistance. These polymerization initiators may be used alone or in combination of two or more.

[0017] Examples of the organic alkali metal amide compound include those obtained by reacting an organic alkali metal compound with a secondary amine compound. Among them, in the production method of the present invention, a compound represented by the following general formula (2) can be preferably used. [ka]

[0018] In general formula (2), M 1 represents an alkali metal atom, and R 11 , R 12 each independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, a protecting group for an amino group, or a group capable of generating a hydroxyl group upon hydrolysis; R 11 and R 12 may be bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, and when forming such a ring structure, they may form a ring structure together with, in addition to the nitrogen atom to which they are bonded, a heteroatom other than the nitrogen atom to which they are bonded.

[0019] The alkyl group is not particularly limited, but is preferably an alkyl group having 1 to 20 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms. Examples of such an alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, and an n-decyl group.

[0020] The cycloalkyl group is not particularly limited, but is preferably a cycloalkyl group having 3 to 20 carbon atoms, and more preferably a cycloalkyl group having 3 to 12 carbon atoms. Examples of such cycloalkyl groups include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and a cyclododecyl group.

[0021] The aryl group is not particularly limited, but is preferably an aryl group having 6 to 12 carbon atoms, and more preferably an aryl group having 6 to 10 carbon atoms. Examples of such aryl groups include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0022] The aralkyl group is not particularly limited, but is preferably an aralkyl group having 7 to 13 carbon atoms, and more preferably an aralkyl group having 7 to 9 carbon atoms. Examples of such aralkyl groups include a benzyl group and a phenethyl group.

[0023] The protecting group for the amino group is not particularly limited as long as it acts as a protecting group for the amino group, and examples thereof include alkylsilyl groups, etc. Examples of such alkylsilyl groups include trimethylsilyl groups, triethylsilyl groups, triphenylsilyl groups, methyldiphenylsilyl groups, ethylmethylphenylsilyl groups, and tert-butyldimethylsilyl groups. In addition, R 11 and / or R 12 is a protecting group for an amino group, the protecting group for the amino group is removed, and the R 13 and / or R 14 It is possible to introduce a structure in which is a hydrogen atom.

[0024] The group that can be hydrolyzed to generate a hydroxyl group is not particularly limited as long as it is a group that generates a hydroxyl group by hydrolysis in the presence of an acid or the like, and examples of the group include an alkoxyalkyl group and a group containing an epoxy group. Examples of the alkoxyalkyl group include a methoxymethyl group, an ethoxymethyl group, an ethoxyethyl group, a propoxymethyl group, a butoxymethyl group, a butoxyethyl group, and a propoxyethyl group. Examples of the group containing an epoxy group include a group represented by the following general formula (3). -Z 1 -Z 2 -E 1 (3) In general formula (3), Z 1 is an alkylene group or an alkylarylene group having 1 to 10 carbon atoms, Z 2 is a methylene group, a sulfur atom or an oxygen atom, and E 1 is a glycidyl group.

[0025] Also, R 11 and R 12 may be bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, in which case, R 11 and R 12 A specific example of the structure formed by the nitrogen atom bonded to the ring is an azetidine ring (R 11 and R 12 propylene group), pyrrolidine ring (R 11 and R 12 butylene group), piperidine ring (R 11 and R 12 pentylene group), hexamethyleneimine ring (R 11 and R 12 However, hexylene groups are also included. R 11 and R 12 When they are bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, the ring structure is preferably a 4- to 8-membered ring structure.

[0026] In addition, in the general formula (2), M1 is an alkali metal atom, and examples of such an alkali metal atom include a lithium atom, a sodium atom, and a potassium atom. Among these, a lithium atom is preferred from the viewpoint of polymerization activity.

[0027] In the first step of the production method of the present invention, when a compound represented by general formula (2) is used as a polymerization initiator, the amine structure forming the organic alkali metal amide compound remains in a state of being bonded to the polymerization initiation terminal of the polymer chain. Therefore, when a compound represented by general formula (2) is used as a polymerization initiator, a structure represented by the following general formula (4) is introduced to one terminal of the polymer chain forming the obtained conjugated diene rubber. [ka]

[0028] In general formula (4), R 13 , R 14 each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, a protecting group for an amino group, or a group capable of generating a hydroxyl group upon hydrolysis; R 13 and R 14 may be bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, and when forming such a ring structure, they may form a ring structure together with, in addition to the nitrogen atom to which they are bonded, a heteroatom other than the nitrogen atom to which they are bonded.

[0029] R 13 , R 14 Examples of the alkyl group, cycloalkyl group, aryl group, aralkyl group, protecting group for amino group, or group capable of generating a hydroxyl group upon hydrolysis include R 11 , R 12 The same can be mentioned as R 13 and R 14 In the case where R is bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, 11 , R 12 can be the same as In addition, R 13 , R 14 The hydrogen atom capable of being introduced is introduced by removing the protecting group of the amino group.

[0030] In the production method of the present invention, when an organic alkali metal amide compound is used as a polymerization initiator, the resulting conjugated diene rubber can have an amine structure at one end and a specific structure derived from a modifier at the other end. As a result, due to the effect of such an amine structure, the rubber cross-linked product using the resulting modified conjugated diene rubber has improved fuel economy.

[0031] The method of adding the organic alkali metal amide compound as a polymerization initiator to the polymerization system is not particularly limited, and a method of reacting an organic alkali metal compound with a secondary amine compound in advance to obtain an organic alkali metal amide compound, which is then mixed with a monomer containing a conjugated diene compound to proceed with the polymerization reaction can be adopted. Alternatively, a method of separately adding an organic alkali metal compound and a secondary amine compound to the polymerization system, mixing them with a monomer containing a conjugated diene compound to generate an organic alkali metal amide compound in the polymerization system, and proceeding with the polymerization reaction can be adopted. The reaction conditions such as the reaction temperature are not particularly limited, and may be, for example, in accordance with the desired polymerization reaction conditions.

[0032] The amount of the secondary amine compound used may be determined depending on the amount of the polymerization initiator to be added, but is usually in the range of 0.01 to 1.5 mmol, preferably 0.1 to 1.2 mmol, and more preferably 0.5 to 1.0 mmol, per 1 mmol of the organic alkali metal compound.

[0033] The amount of the polymerization initiator used may be determined depending on the molecular weight of the desired conjugated diene polymer chain, but is usually in the range of 1 to 50 mmol, preferably 1.5 to 20 mmol, and more preferably 2 to 15 mmol per 1000 g of monomer.

[0034] The polymerization temperature is usually in the range of −80 to +150° C., preferably 0 to 100° C., and more preferably 30 to 90° C. As the polymerization mode, any mode such as a batch mode or a continuous mode can be adopted, but when a conjugated diene compound and an aromatic vinyl compound are copolymerized, the batch mode is preferred in that it is easy to control the randomness of the bonds between the conjugated diene monomer units and the aromatic vinyl monomer units.

[0035] In the first step of the production method of the present invention, it is preferable to carry out the polymerization in the presence of a polar compound when polymerizing a monomer containing a conjugated diene compound. Specifically, the polar compound is preferably used in an amount of 0.01 to 5.0 mol, more preferably 0.1 to 4.0 mol, and even more preferably 0.2 to 3.0 mol per mol of the polymerization initiator, and the polymerization is carried out in the presence of such a polar compound, so that the vinyl bond content in the conjugated diene monomer unit portion contained in the conjugated diene polymer chain obtained in the first step can be suitably adjusted. Specifically, the vinyl bond content in the conjugated diene monomer unit portion contained in the conjugated diene polymer chain can be preferably 70% by weight or less, more preferably 68% by weight or less, and even more preferably 65% ​​by weight or less. In addition, the lower limit of the vinyl bond content is not particularly limited, but is preferably 5% by weight or more, more preferably 10% by weight or more, and even more preferably 20% by weight or more. By setting the vinyl bond content in the conjugated diene monomer unit portion contained in the conjugated diene polymer chain within the above range, the vinyl bond content in the conjugated diene monomer unit portion contained in the finally obtained conjugated diene rubber can be set to 70% by weight or less, and thus the obtained cross-linked rubber product can have improved fuel economy.

[0036] The method of carrying out polymerization in the presence of a polar compound is not particularly limited, but may be, for example, a method of carrying out polymerization by adding a polar compound to an inert solvent used for polymerization. Specific examples of polar compounds include ethers such as tetrahydrofuran, diethyl ether, dibutyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, and 2,2-di(tetrahydrofuryl)propane; tertiary amine compounds such as tetramethylethyleneamine, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxide compounds such as potassium-t-amyloxide and potassium-t-butyloxide; and phosphine compounds such as triphenylphosphine. Among these, polar compounds capable of multidentate coordination are more preferable, and tetramethylethylenediamine is particularly preferable. These polar compounds may be used alone or in combination of two or more.

[0037] The peak top molecular weight (Mp), which is the peak of the lowest region of the molecular weight of the conjugated diene polymer chain having an active end obtained in the first step of the production method of the present invention, is not particularly limited, but is preferably 100,000 to 1,000,000, more preferably 150,000 to 700,000, and particularly preferably 150,000 to 500,000, as a value measured by gel permeation chromatography in terms of polystyrene.

[0038] In addition, the molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the conjugated diene polymer chain having an active end obtained in the first step of the production method of the present invention is not particularly limited, but is preferably 1.0 to 3.0, and more preferably 1.0 to 2.5. When the molecular weight distribution (Mw / Mn) of the conjugated diene polymer chain having an active end is within the above range, the production of the conjugated diene rubber becomes easy.

[0039] In the production method of the present invention, in order to obtain a cross-linked rubber product with improved fuel economy, it is preferable that the first step is the following step. That is, a step of polymerizing isoprene or a monomer containing isoprene and an aromatic vinyl compound in an inert solvent with a polymerization initiator to form a polymer block (A) having an active terminal containing 80 to 100% by weight of isoprene monomer units; and mixing the polymer block (A) having an active end with a monomer containing 1,3-butadiene or 1,3-butadiene and an aromatic vinyl compound to continue the polymerization reaction, thereby forming a polymer block (B) having an active end containing 50 to 100% by weight of 1,3-butadiene monomer units and 0 to 50% by weight of aromatic vinyl monomer units in a continuous manner with the polymer block (A), thereby obtaining a conjugated diene-based polymer chain having an active end.

[0040] By employing such a process, the conjugated diene polymer chain having an active terminal obtained in the first process and the resulting modified conjugated diene polymer can be made to contain an isoprene-containing block (A) containing 80 to 100% by weight of isoprene units, and more preferably, the resulting modified conjugated diene polymer can be made to contain a polymer block (A) containing 80 to 100% by weight of isoprene monomer units and a polymer block (B) containing 50 to 100% by weight of 1,3-butadiene monomer units and 0 to 50% by weight of aromatic vinyl monomer units, which are formed in series. Such an embodiment will be described below.

[0041] [Polymer block (A)] The polymer block (A) in the conjugated diene polymer chain according to one embodiment of the present invention may contain 80-100% by weight of isoprene monomer units, preferably 80-100% by weight of isoprene monomer units and 0-20% by weight of aromatic vinyl monomer units, more preferably 85-97% by weight of isoprene monomer units and 3-15% by weight of aromatic vinyl monomer units, and even more preferably 89-95% by weight of isoprene monomer units and 5-11% by weight of aromatic vinyl monomer units. If the content of isoprene monomer units is within the above range, when silica is blended with the modified conjugated diene rubber, the affinity between the modified conjugated diene rubber and silica is good, and the fuel economy of the cross-linked rubber obtained by using this can be further improved.

[0042] The aromatic vinyl compound used to constitute the aromatic vinyl monomer unit contained in the polymer block (A) may be the same as the aromatic vinyl compound described above, and among these, styrene is preferred. These aromatic vinyl compounds may be used alone or in combination of two or more.

[0043] The polymer block (A) preferably consists of only isoprene monomer units, or isoprene monomer units and aromatic vinyl monomer units, but may contain other monomer units in addition to the isoprene monomer units, or isoprene monomer units and aromatic vinyl monomer units, if desired. Other compounds used to form the other monomer units include conjugated diene compounds other than isoprene, such as 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene; α,β-unsaturated nitriles, such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acids or acid anhydrides, such as acrylic acid, methacrylic acid, and maleic anhydride; unsaturated carboxylic acid esters, such as methyl methacrylate, ethyl acrylate, and butyl acrylate; non-conjugated dienes, such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene; and the like. Among these, 1,3-butadiene is preferred. These other monomers can be used alone or in combination of two or more. The content of other monomer units in the polymer block (A) is preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably 6% by weight or less.

[0044] In the present invention, the polymer block (A) in the conjugated diene polymer chain is formed by polymerizing a monomer containing isoprene or a monomer containing isoprene and an aromatic vinyl compound with a polymerization initiator in an inert solvent. The formed polymer block (A) has an active terminal.

[0045] The inert solvent used in the polymerization of isoprene or a monomer containing isoprene and an aromatic vinyl compound to form the polymer block (A) may be the same as the inert solvent described above. The amount of the inert solvent used is preferably an amount that results in a monomer concentration of 1 to 80% by weight, more preferably an amount that results in a monomer concentration of 10 to 50% by weight.

[0046] The polymerization initiator used to form the polymer block (A) is not particularly limited as long as it can polymerize isoprene or a monomer containing isoprene and an aromatic vinyl compound to give a polymer chain having an active terminal. Specific examples of the polymerization initiator include the same as those described above.

[0047] The amount of the polymerization initiator used may be determined depending on the target molecular weight, but is preferably in the range of 4 to 250 mmol, more preferably 6 to 200 mmol, and particularly preferably 10 to 70 mmol, per 100 g of isoprene or a monomer containing isoprene and an aromatic vinyl compound.

[0048] The polymerization temperature when polymerizing isoprene or a monomer containing isoprene and an aromatic vinyl compound is preferably in the range of -80 to +150°C, more preferably 0 to 100°C, and further preferably 20 to 90°C. Any polymerization mode, such as a batch mode or a continuous mode, can be adopted. In addition, various bonding modes, such as a block mode, a tapered mode, and a random mode, can be adopted.

[0049] In the production method according to one aspect of the present invention, it is preferable to polymerize isoprene or a monomer containing isoprene and an aromatic vinyl compound in the presence of a polar compound when forming the polymer block (A). Specifically, the vinyl bond content of the isoprene monomer unit portion in the polymer block (A) can be suitably adjusted by using preferably 0.01 to 30 mol, more preferably 0.03 to 10 mol, and even more preferably 0.05 to 5 mol of the polar compound relative to 1 mol of the polymerization initiator and carrying out the polymerization in the presence of such a polar compound. The vinyl bond content of the isoprene monomer unit portion in the polymer block (A) is preferably 25% by weight or less, more preferably 20% by weight or less, and even more preferably 15% by weight or less. The lower limit of the vinyl bond content is not particularly limited, but is preferably 1% by weight or more, and more preferably 5% by weight or more. By setting the vinyl bond content of the isoprene monomer unit portion within the above range, the fuel economy of the obtained cross-linked rubber can be further improved. The vinyl bond in the isoprene monomer unit portion may be either a 1,2-vinyl bond or a 3,4-vinyl bond.

[0050] The method of polymerizing isoprene or a monomer containing isoprene and an aromatic vinyl compound in the presence of a polar compound is not particularly limited, but may be, for example, a method of adding a polar compound to an inert solvent used in the polymerization and carrying out the polymerization. In addition, the same polar compounds as those described above can be used as the polar compound.

[0051] The weight average molecular weight (Mw) of the polymer block (A), expressed as a polystyrene equivalent value measured by gel permeation chromatography, is preferably 500 to 15,000, more preferably 1,000 to 12,000, and particularly preferably 1,500 to 10,000. When the weight average molecular weight of the polymer block (A) is within the above range, the fuel economy of the obtained cross-linked rubber can be further improved.

[0052] The molecular weight distribution of the polymer block (A), which is expressed by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 1.0 to 1.5, more preferably 1.0 to 1.3. When the molecular weight distribution value (Mw / Mn) of the polymer block (A) is within the above range, the production of the modified conjugated diene rubber becomes easier.

[0053] [Polymer block (B)] The polymer block (B) in the conjugated diene polymer chain according to one embodiment of the present invention may contain 50-100% by weight of 1,3-butadiene monomer units and 0-50% by weight of aromatic vinyl monomer units, but preferably contains 52-98% by weight of 1,3-butadiene monomer units and 2-48% by weight of aromatic vinyl monomer units, and more preferably contains 55-84% by weight of 1,3-butadiene monomer units and 16-45% by weight of aromatic vinyl monomer units. When the content ratio of 1,3-butadiene monomer units and aromatic vinyl monomer units is within the above range, the production of modified conjugated diene rubber becomes easier.

[0054] As the aromatic vinyl compound used to constitute the aromatic vinyl monomer unit contained in the polymer block (B), the same aromatic vinyl compounds as those mentioned above can be used, and among these, styrene is preferred.

[0055] The polymer block (B) is preferably composed of only 1,3-butadiene monomer units, or 1,3-butadiene monomer units and aromatic vinyl monomer units, but may contain other monomer units in addition to 1,3-butadiene monomer units, or 1,3-butadiene monomer units and aromatic vinyl monomer units, as desired, within the range that does not impair the essential characteristics of the present invention. As other monomers used to constitute the other monomer units, the same compounds exemplified in the above-mentioned polymer block (A) (excluding 1,3-butadiene) can be used. In addition, isoprene can also be used as the other monomer in the polymer block (B). The content ratio of other monomer units in the polymer block (B) is preferably 50% by weight or less, more preferably 40% by weight or less, and even more preferably 35% by weight or less.

[0056] In one embodiment of the present invention, the polymer block (B) in the conjugated diene polymer chain is formed in a continuous manner with the polymer block (A) by mixing the polymer block (A) having the above-mentioned active terminal with a monomer containing 1,3-butadiene or 1,3-butadiene and an aromatic vinyl compound and continuing the polymerization reaction. The formed polymer block (B) has an active terminal. On the other hand, the active terminal disappears from the polymer block (A).

[0057] The inert solvent used in the polymerization of the polymer block (A) with a monomer containing 1,3-butadiene or 1,3-butadiene and an aromatic vinyl compound to form the polymer block (B) is not particularly limited, and the same inert solvents as those described above can be used.

[0058] The amount of the polymer block (A) having an active end used in forming the polymer block (B) may be determined depending on the target molecular weight, but is preferably in the range of 0.1 to 5 mmol, more preferably 0.15 to 2 mmol, and even more preferably 0.2 to 1.5 mmol, per 100 g of 1,3-butadiene or a monomer containing 1,3-butadiene and an aromatic vinyl compound.

[0059] The method of mixing the polymer block (A) with 1,3-butadiene or a monomer containing 1,3-butadiene and an aromatic vinyl compound is not particularly limited, and the polymer block (A) having an active end may be added to a solution of 1,3-butadiene or a monomer containing 1,3-butadiene and an aromatic vinyl compound, or 1,3-butadiene or a monomer containing 1,3-butadiene and an aromatic vinyl compound may be added to a solution of the polymer block (A) having an active end. From the viewpoint of controlling the polymerization, the method of adding the polymer block (A) having an active end to a solution of 1,3-butadiene or a monomer containing 1,3-butadiene and an aromatic vinyl compound is preferred.

[0060] The polymerization temperature when polymerizing 1,3-butadiene or a monomer containing 1,3-butadiene and an aromatic vinyl compound is preferably in the range of -80 to +150°C, more preferably 0 to 100°C, and further preferably 20 to 90°C. As the polymerization mode, any mode such as a batch system or a continuous system can be adopted. When the polymer block (B) is a copolymer chain, the batch system is preferred in that it is easy to control the randomness of the bonds.

[0061] When the polymer block (B) is a copolymer chain, the bonding pattern of each monomer can be various bonding patterns such as block, tapered, and random. Among these, the random bonding pattern is preferable. By making the bonding pattern random, the wet grip property and abrasion resistance of the obtained cross-linked rubber can be further improved. When making the bonding pattern of 1,3-butadiene and aromatic vinyl compound random, it is preferable to polymerize 1,3-butadiene or 1,3-butadiene and aromatic vinyl compound by continuously or intermittently supplying them into the polymerization system so that the ratio of aromatic vinyl compound to the total amount of 1,3-butadiene and aromatic vinyl compound in the polymerization system is not too high.

[0062] In one embodiment of the present invention, similarly to the formation of the polymer block (A), when forming the polymer block (B), it is preferable to polymerize a monomer containing 1,3-butadiene or 1,3-butadiene and an aromatic vinyl compound in the presence of a polar compound. Specifically, by using preferably 0.01 to 5.0 mol, more preferably 0.1 to 4.0 mol, and even more preferably 0.2 to 3.0 mol of a polar compound relative to 1 mol of a polymerization initiator and carrying out polymerization in the presence of such a polar compound, it is possible to suitably adjust the vinyl bond content of the 1,3-butadiene monomer unit portion in the polymer block (B), and as a result, it is possible to suitably adjust the vinyl bond content of the conjugated diene monomer unit portion contained in the finally obtained conjugated diene rubber. The vinyl bond content of the 1,3-butadiene monomer unit portion in the polymer block (B) is preferably 70% by weight or less, more preferably 68% by weight or less, and even more preferably 65% ​​by weight or less. Further, the lower limit of the vinyl bond content is not particularly limited, but is preferably 5% by weight or more, more preferably 10% by weight or more, and further preferably 20% by weight or more.

[0063] The method of polymerizing 1,3-butadiene or a monomer containing 1,3-butadiene and an aromatic vinyl compound in the presence of a polar compound is not particularly limited, but may be, for example, a method of adding a polar compound to an inert solvent used for polymerization and polymerizing the monomer. In this case, the polar compound may be added so that the total amount of the polar compound added when forming the polymer block (A) and the amount of the polar compound newly added is within the above-mentioned range. Therefore, if a polar compound is added in an amount sufficient to adjust the vinyl bond content of the 1,3-butadiene monomer unit portion in the polymer block (B) when forming the polymer block (A), it is not necessary to add a new polar compound. In addition, the polar compound may be the same as the polar compound described above.

[0064] In this way, a conjugated diene polymer chain having an active end, which has a polymer block (A) and a polymer block (B), can be obtained. In one aspect of the present invention, the conjugated diene polymer chain having an active end is preferably composed of a polymer block (A)-polymer block (B) from the viewpoint of productivity, and the end of the polymer block (B) is preferably an active end, but may have a plurality of polymer blocks (A) or may have other polymer blocks. For example, a conjugated diene polymer chain having an active end, such as a polymer block (A)-polymer block (B)-polymer block (A), may be mentioned. In this case, an active end is formed at the end of the polymer block (A) formed following the polymer block (B). When forming the polymer block (A) on the active end side of the conjugated diene polymer chain, the amount of isoprene used is preferably 10 to 100 mol, more preferably 20 to 90 mol, and particularly preferably 30 to 70 mol, relative to 1 mol of the polymerization initiator used in the initial polymerization reaction (polymerization reaction for forming the first polymer block (A)).

[0065] The weight ratio of polymer block (A) to polymer block (B) in the conjugated diene polymer chain having an active end obtained in one embodiment of the present invention (when a plurality of polymer blocks (A) and polymer blocks (B) are present, the weight ratio is based on the total weight of each) (weight of polymer block (A)) / (weight of polymer block (B)) is preferably 0.001 to 0.2, more preferably 0.005 to 0.1, and particularly preferably 0.008 to 0.05. By setting the weight ratio of polymer block (A) to polymer block (B) within the above range, the obtained cross-linked rubber product can have improved fuel economy.

[0066] The content ratio of the total monomer units of isoprene monomer units and 1,3-butadiene monomer units and aromatic vinyl monomer units in the conjugated diene polymer chain having an active end, which has polymer block (A) and polymer block (B), is preferably 50 to 100% by weight of the total monomer units of isoprene monomer units and 1,3-butadiene monomer units and 0 to 50% by weight of aromatic vinyl monomer units, more preferably 52 to 98% by weight of the total monomer units of isoprene monomer units and 1,3-butadiene monomer units and 2 to 48% by weight of aromatic vinyl monomer units, and particularly preferably 55 to 84% by weight of the total monomer units of isoprene monomer units and 1,3-butadiene monomer units and 16 to 45% by weight of aromatic vinyl monomer units. In addition, the vinyl bond contents in the isoprene monomer units and the 1,3-butadiene monomer units in the conjugated diene polymer chain having an active end, which has the polymer block (A) and the polymer block (B), are preferably in the same range as the vinyl bond content in the 1,3-butadiene monomer units in the above-mentioned polymer block (B).

[0067] The above-mentioned polar compound may be further added before the second step of the present invention. Specifically, the amount of the polar compound added before the second step, more specifically, the total amount of the polar compound added in the first step, is preferably 0.5 to 5.0 mol, more preferably 0.6 to 4.0 mol, and particularly preferably 0.9 to 3.0 mol, relative to 1 mol of the polymerization initiator, so that the association state of the conjugated diene polymer chain having an active terminal can be suitably adjusted, and as a result, the maximum power load of the stirrer in the second step can be suitably adjusted.

[0068] <Second process> The second step of the production method of the present invention is a step of reacting the conjugated diene polymer chain having an active end obtained in the first step with the polyorganosiloxane represented by the following general formula (1) by continuously adding the polyorganosiloxane to the conjugated diene polymer chain having an active end over a period of 2 to 60 minutes or by adding the polyorganosiloxane in multiple divided portions. [ka] (In the above general formula (1), R 1 ~R 8 is a hydrocarbon group having 1 to 20 carbon atoms, and these may be the same or different. X 1 and X 4 is a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a polar functional group having an atom of Group 15 or Group 16 of the periodic table, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may have the polar functional group or a halogen atom, and these may be the same or different. X 2 is a polar functional group having an atom of Group 15 or 16 of the periodic table, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may have the polar functional group or a halogen atom, and X 2 When there are multiple X's, they may be the same or different. 3 is a group containing 2 to 20 repeating alkylene glycol units, X 3A part of X may be a group derived from a group containing 2 to 20 repeating units of alkylene glycol; 3 When there are a plurality of, they may be the same or different. m is an integer of 1 to 200, n is an integer of 0 to 200, and k is an integer of 0 to 200.)

[0069] R in general formula (1) 1 ~R 8 is a hydrocarbon group having 1 to 20 carbon atoms, preferably an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, more preferably 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. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, and a cyclohexyl group. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group and a methylphenyl group. Among these, from the viewpoint of ease of production of the polyorganosiloxane itself, a methyl group and an ethyl group are preferred, and a methyl group is more preferred.

[0070] X in general formula (1) 1 and X 4 is a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a polar functional group having an atom of Group 15 or Group 16 of the periodic table, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may have the polar functional group or a halogen atom, and these may be the same or different. X 1 and X 4The alkyl group is preferably any one selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, a hydrocarbon group having 1 to 5 carbon atoms and an alkoxy group (a hydrocarbon group having a total of 1 to 5 carbon atoms including the carbon atoms constituting the alkoxy group), and a hydrocarbon group having 4 to 12 carbon atoms and an epoxy group (a hydrocarbon group having a total of 4 to 12 carbon atoms including the carbon atoms constituting the epoxy group). More preferably, the alkyl group has 4 to 12 carbon atoms and an epoxy group, or an alkyl group having 1 to 6 carbon atoms, and even more preferably, an alkyl group having 1 to 6 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, and a cyclohexyl group. Among these, from the viewpoint of the ease of production of the polyorganosiloxane itself, a methyl group and an ethyl group are preferable, and a methyl group is more preferable.

[0071] X in general formula (1) 2 is a polar functional group having an atom of Group 15 or 16 of the periodic table, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may have the polar functional group or a halogen atom, and X 2 When there are multiple X's, they may be the same or different. 2 is preferably a hydrocarbon group having 1 to 20 carbon atoms which may have a polar functional group having an oxygen atom, more preferably a hydrocarbon group having 1 to 20 carbon atoms which may have an alkoxy group or an epoxy group, even more preferably a hydrocarbon group having 1 to 5 carbon atoms which has an alkoxy group or a hydrocarbon group having 4 to 12 carbon atoms which has an epoxy group, and even more preferably a hydrocarbon group having 4 to 12 carbon atoms which has an epoxy group.

[0072] Examples of the hydrocarbon group having 1 to 5 carbon atoms and having an alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, and a butoxy group. Among these, from the viewpoint of ease of production of the polyorganosiloxane itself, a methoxy group and an ethoxy group are preferred.

[0073] An example of the epoxy group-containing hydrocarbon group having 4 to 12 carbon atoms is a group represented by the following general formula (5). -Z 3 -Z 4 -E 2 (5) In general formula (5), Z 3 is an alkylene group or an alkylarylene group having 1 to 10 carbon atoms; Z 4 is a methylene group, a sulfur atom, or an oxygen atom, and E 2 is a hydrocarbon group having 2 to 10 carbon atoms and an epoxy group (a hydrocarbon group having a total of 2 to 10 carbon atoms including the carbon atoms constituting the epoxy group).

[0074] The group represented by formula (5) is Z 4 is preferably an oxygen atom, and Z 4 is an oxygen atom, and E 2 is more preferably a glycidyl group, and Z 3 is an alkylene group having 1 to 3 carbon atoms, and Z 4 is an oxygen atom, and E 2 is particularly preferably a glycidyl group.

[0075] X 3 is a group containing 2 to 20 repeating alkylene glycol units, X 3 A part of X may be a group derived from a group containing 2 to 20 repeating units of alkylene glycol; 3 When there are a plurality of these, they may be the same or different. As the group containing 2 to 20 repeating units of alkylene glycol, a group represented by the following general formula (6) is preferred. [ka] In the general formula (6), t is an integer of 2 to 20, and X 5 is an alkylene group or alkylarylene group having 2 to 10 carbon atoms, R 15 is a hydrogen atom or a methyl group, and X 6is an alkoxy group or an aryloxy group having 1 to 10 carbon atoms. Among these, t is an integer of 2 to 8, and X 5 is an alkylene group having 3 carbon atoms, and R 15 is a hydrogen atom and X 6 is preferably a methoxy group.

[0076] In the polyorganosiloxane represented by the general formula (1), m is an integer of 1 to 200, preferably an integer of 20 to 150, and more preferably an integer of 30 to 120. When m is 1 or more, the fuel economy of the obtained cross-linked rubber product can be further improved. In addition, when m is 200 or less, the production of the polyorganosiloxane represented by the general formula (1) itself becomes easier, and the viscosity does not become too high, making it easier to handle.

[0077] In the polyorganosiloxane represented by the general formula (1), n ​​is an integer of 0 to 200, preferably an integer of 0 to 150, more preferably an integer of 0 to 120. k is an integer of 0 to 200, preferably an integer of 0 to 150, more preferably an integer of 0 to 130. The total number of m, n, and k is 1 or more, preferably 3 to 400, more preferably 20 to 300, and particularly preferably 30 to 250. When the total number of m, n, and k is 1 or more, the reaction between the polyorganosiloxane represented by the general formula (1) and the conjugated diene polymer chain having an active terminal easily proceeds, and when the total number of m, n, and k is 400 or less, the polyorganosiloxane represented by the general formula (1) itself is easily produced, and the viscosity does not become too high, making it easy to handle.

[0078] The amount of polyorganosiloxane represented by general formula (1) used in the second step of the production method of the present invention is, relative to 1 mole of the polymerization initiator used in the polymerization in the first step described above, preferably 0.1 moles or more, more preferably 0.15 moles or more, even more preferably 0.2 moles or more, particularly preferably 0.3 moles or more, and also preferably 2 moles or less, more preferably 1.5 moles or less, even more preferably 1 mole or less, particularly preferably 0.8 moles or less, calculated as a polar functional group such as an epoxy group or a halogen atom in the polyorganosiloxane. When the amount of polyorganosiloxane used is within the above range, the fuel economy of the obtained rubber cross-linked product can be further improved.

[0079] In the second step of the production method of the present invention, when reacting the polyorganosiloxane represented by general formula (1) with the conjugated diene polymer chain having an active end obtained in the first step, it is preferable to continuously add the polyorganosiloxane represented by general formula (1) to the conjugated diene polymer chain having an active end over a period of 2 to 60 minutes, or to add it in portions in several portions, and react them.

[0080] In this case, the polyorganosiloxane represented by the general formula (1) is added continuously for 2 to 60 minutes or in several divided portions while stirring the polymer solution obtained by dissolving the conjugated diene polymer chain having an active terminal in an inert solvent capable of dissolving the conjugated diene polymer chain with an active terminal by a stirrer or the like. In addition, as the inert solvent used in this case, it is preferable to use an inert solvent capable of dissolving both the conjugated diene polymer chain having an active terminal and the polyorganosiloxane represented by the general formula (1), and the inert solvents described above can be used. In addition, in this case, it is preferable to add the polyorganosiloxane represented by the general formula (1) continuously or in several divided portions to the polymerization solution used in the polymerization to obtain the conjugated diene polymer chain having an active terminal, which is convenient.

[0081] According to the present invention, the polyorganosiloxane represented by the general formula (1) is added continuously to the conjugated diene polymer chain having an active terminal over 2 to 60 minutes, or the method of adding the polyorganosiloxane in several divided portions is adopted, so that the resulting modified conjugated diene polymer has good fuel economy and can be produced with high productivity. Specifically, when the polyorganosiloxane represented by the general formula (1) is reacted with the conjugated diene polymer chain having an active terminal, as described above, it is usually performed by mixing them in an inert solvent capable of dissolving them using a stirrer or the like, but when mixing them, the maximum power load of the stirrer can be reduced, which makes it possible to reduce the energy required for production. Furthermore, it is possible to carry out the reaction under relatively high polymer concentration conditions for the inert solvent used while suppressing the increase in the maximum power load of the stirrer. Therefore, these make it possible to improve productivity. Although the reason for this is not entirely clear, it is believed that the proportion of multi-branched bodies having two or more branches produced can be reduced by continuously adding the polyorganosiloxane represented by general formula (1) to the conjugated diene polymer chain having an active terminal over a period of 2 to 60 minutes, or by adding the polyorganosiloxane in several divided portions.

[0082] In the method of continuously adding the polyorganosiloxane represented by the general formula (1) to the conjugated diene polymer chain having an active terminal over 2 to 60 minutes, the polyorganosiloxane represented by the general formula (1) used for modification may be added substantially continuously, and may be added continuously at a constant addition rate (constant addition amount), or may be added intermittently and continuously in a short interval of preferably 1 second to less than 2 minutes, more preferably 1 second to 60 seconds. In addition, when adding continuously, it is preferable to add continuously at a constant addition rate (constant addition amount) or to add intermittently in a constant amount, but it may be added continuously or intermittently while varying the addition amount within a range of, for example, ±200%.

[0083] The addition time when the polyorganosiloxane represented by the general formula (1) is continuously added to the conjugated diene polymer chain having an active terminal is 2 to 60 minutes, preferably 3 to 50 minutes, more preferably 4 to 40 minutes, and further preferably 5 to 30 minutes. If the addition time is too short during the continuous addition, the effect of reducing the maximum power load of the stirrer cannot be obtained, and the productivity decreases, whereas if the addition time is too long during the continuous addition, the production time increases and the productivity decreases.

[0084] In addition, in the method of adding the polyorganosiloxane represented by the general formula (1) to the conjugated diene polymer chain having an active terminal in multiple divided portions, the polyorganosiloxane represented by the general formula (1) used for modification may be divided into two or more portions and then added in portions. For example, when adding in two divided portions, a predetermined amount may be added in the first stage, the modification reaction may proceed, and then after a predetermined interval, the remainder may be added in the second stage. Similarly, when adding in three divided portions, a predetermined amount may be added in the first stage, the modification reaction may proceed, and then after a predetermined interval, a further predetermined amount may be added in the second stage, the modification reaction may proceed, and then after a predetermined interval, the remainder may be added in the third stage. The same may be done in the case of adding in four or more divided portions.

[0085] The amount added at each addition timing in the divided addition is not particularly limited, and may be the same amount or different amounts at each addition timing, but from the viewpoint of a high productivity improvement effect, it is preferable to add the same amount at each addition timing or to add the largest amount in the first stage. For example, when adding in two divided times, it is preferable that the amount added in the first stage:the amount added in the second stage=55:45 to 80:20 (weight ratio).

[0086] From the viewpoint of improving productivity, the addition time at each addition timing in divided addition is preferably less than 2 minutes, more preferably 1 second to less than 1 minute. From the viewpoint of improving productivity, the interval between each addition timing (the interval between the Nth stage divided addition and the N+1th stage divided addition) is preferably 1 to 30 minutes, more preferably 2 to 25 minutes, and even more preferably 5 to 20 minutes.

[0087] In the second step of the present invention, it is preferable to add the entire amount of the polyorganosiloxane represented by the general formula (1) used for modification continuously, or to add the entire amount of the polyorganosiloxane represented by the general formula (1) used for modification in portions, but a method of adding a part of it continuously and adding the rest in portions may be adopted. In this case, a method of adding it continuously first and then in portions may be adopted, or a method of adding it in portions first and then in continuous addition may be adopted.

[0088] In addition, when the polyorganosiloxane represented by the general formula (1) used for modification is added continuously or in portions, the polyorganosiloxane represented by the general formula (1) may be added directly without being dissolved in an inert solvent, or the polyorganosiloxane represented by the general formula (1) may be added in the form of a solution by dissolving it in an inert solvent capable of dissolving it. In this case, the solution concentration is preferably in the range of 1 to 50% by weight.

[0089] In the second step, the polyorganosiloxane represented by general formula (1) is added continuously or in portions to the conjugated diene polymer chain having an active terminal, thereby reacting the polyorganosiloxane represented by general formula (1) with the conjugated diene polymer chain having an active terminal, and the reaction temperature is usually 0 to 120° C., preferably 30 to 90° C. The reaction time in the second step is not particularly limited, but is preferably 2 to 120 minutes, more preferably 5 to 60 minutes.

[0090] The timing for starting the continuous or divided addition of the polyorganosiloxane represented by general formula (1) to the conjugated diene polymer chain having an active terminal is not particularly limited, but it is preferable to start the addition when the polymerization reaction is not completed and the solution containing the conjugated diene polymer chain having an active terminal also contains a monomer, more specifically, when the solution containing the conjugated diene polymer chain having an active terminal contains 100 ppm or more, more preferably 300 to 50,000 ppm of a monomer.

[0091] After reacting the polyorganosiloxane represented by general formula (1) with the conjugated diene polymer chain having an active terminal, it is preferable to add a polymerization terminator such as an alcohol such as methanol, ethanol, or isopropanol, or water to deactivate the unreacted active terminal.

[0092] After deactivating the active end of the conjugated diene polymer chain, if desired, an antiaging agent such as a phenol-based stabilizer, a phosphorus-based stabilizer, or a sulfur-based stabilizer, a crumbing agent, and a scale inhibitor are added to the reaction solution, and then the inert solvent is separated from the reaction solution by direct drying or steam stripping, etc., to recover the modified conjugated diene rubber. Note that, before separating the inert solvent from the reaction solution, an extender oil may be mixed with the polymerization solution, and the modified conjugated diene rubber may be recovered as an oil-extended rubber.

[0093] Examples of the extender oil used when recovering the modified conjugated diene rubber as an oil-extended rubber include paraffinic, aromatic and naphthenic petroleum-based softeners, vegetable softeners, synthetic softeners using plant-derived resources, and fatty acids. When using a petroleum-based softener, it is preferable that the content of polycyclic aromatics extracted by the IP346 method (testing method of THE INSTITUTE PETROLEUM in the UK) is less than 3%. When using an extender oil, the amount of the extender oil used is preferably 5 to 100 parts by weight, more preferably 10 to 60 parts by weight, and even more preferably 15 to 50 parts by weight, based on 100 parts by weight of the modified conjugated diene rubber.

[0094] The weight average molecular weight (Mw) of the modified conjugated diene rubber is preferably 50,000 to 5,000,000, more preferably 75,000 to 3,000,000, and particularly preferably 100,000 to 1,000,000, as a value measured by gel permeation chromatography in terms of polystyrene.

[0095] The molecular weight distribution of the modified conjugated diene rubber, which is expressed 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 particularly preferably 1.2 to 2.2. By setting the molecular weight distribution (Mw / Mn) of the modified conjugated diene rubber within the above range, the fuel economy of the obtained cross-linked rubber can be further improved.

[0096] Mooney Viscosity (ML) of Modified Conjugated Diene Rubber 1+4 , 100° C.) is preferably 20 to 150, more preferably 30 to 120, and particularly preferably 35 to 90. When the modified conjugated diene rubber is used as an oil-extended rubber, it is preferable that the Mooney viscosity of the oil-extended rubber is within the above range.

[0097] The glass transition temperature (Tg) of the modified conjugated diene rubber is not particularly limited, but is preferably 20° C. to −110° C., more preferably 10° C. to −70° C., particularly preferably 0° C. to −60° C., and most preferably −10° C. to −45° C. The glass transition temperature of the modified conjugated diene rubber of the present invention can be appropriately adjusted, for example, by adjusting the aromatic vinyl monomer unit content in the modified conjugated diene rubber and the vinyl bond content in the modified conjugated diene monomer unit portion.

[0098] In the production method of the present invention, the conjugated diene polymer chain that has been reacted with the polyorganosiloxane represented by general formula (1) and that has been subjected to the second step may be further reacted with a hydrocarbyloxysilane compound.

[0099] Such hydrocarbyloxysilane compounds are not particularly limited, but may be silicon-containing compounds having at least one hydrocarbyloxy group, and may not be polyorganosiloxanes represented by general formula (1). In addition to the hydrocarbyloxy group, it is preferable that the compound has at least one group containing a nitrogen atom, and more preferably, the group containing a nitrogen atom has a primary amino group having an active hydrogen atom and / or a secondary amino group having an active hydrogen atom. The hydrocarbyloxysilane compounds act as modifiers by reacting the hydrocarbyloxy group with the conjugated diene polymer chain having an active terminal, or with the reaction residue generated by the reaction of the conjugated diene polymer chain having an active terminal and the polyorganosiloxane represented by general formula (1).

[0100] Although there is no particular limitation on such a hydrocarbyloxysilane compound, a compound represented by the following general formula (7) can be suitably used. [ka] In the above general formula (7), R 16 is a hydrocarbyl group, A 1 is a hydrocarbyloxy group, 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.

[0101] R in the above general formula (7) 16 is a hydrocarbyl group, and examples of such groups include an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, and an aralkyl group, with an alkyl group having 1 to 6 carbon atoms being preferred. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, a pentyl group, and a hexyl group, with a methyl group and an ethyl group being more preferred among these.

[0102] A in the above general formula (7) 1is a hydrocarbyloxy group, and examples thereof include alkoxy groups such as methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, and tert-butoxy group; alkenyloxy groups such as vinyloxy group and allyloxy group; aryloxy groups such as phenoxy group and naphthoxy group; aralkyloxy groups such as benzyloxy group; etc. Among these, from the viewpoint of reactivity, alkoxy groups and aryloxy groups are preferred, alkoxy groups are more preferred, and methoxy and ethoxy groups are particularly preferred.

[0103] A in the above general formula (7) 2 is a group containing a nitrogen atom, and is not particularly limited as long as it is a group containing a nitrogen atom, but is preferably an organic group having a nitrogen atom, and examples thereof include a 3-aminopropyl group, a 4-aminobutyl group, a 3-(2-aminoethylamino)propyl group, a 2-dimethylaminoethyl group, a 3-dimethylaminopropyl group, a 3-diethylaminopropyl group, a 3-dipropylaminopropyl group, a 3-dibutylaminopropyl group, a 3-phenylmethylaminopropyl group, a 3-(4-methylpiperazinyl)propyl group, a N,N-bis(trimethylsilyl)aminopropyl group, a N,N-bis(triethylsilyl)aminopropyl group, and a N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropyl group. Among these, a group containing a primary amino group having an active hydrogen atom and / or a secondary amino group having an active hydrogen atom, such as a 3-aminopropyl group, a 4-aminobutyl group, or a 3-(2-aminoethylamino)propyl group, is preferred from the viewpoint of further improving the fuel economy of the obtained rubber cross-linked product. The term "active hydrogen atom" refers to a hydrogen atom bonded to an atom other than a carbon atom, and preferably has a bond energy lower than that of the carbon-hydrogen bond of a polymethylene chain.

[0104] In the compound represented by the above general formula (7), 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. From the viewpoint of reactivity with the conjugated diene polymer chain reacted with the polyorganosiloxane represented by the general formula (1) that has been subjected to the second step, p is preferably an integer of 0 to 1, q is an integer of 2 to 3, and r is an integer of 1 to 2, and more preferably p=0, q=3, and r=1. When p is 2, two R groups are contained in one molecule of the compound represented by the general formula (7). 16 The groups represented by may be the same or different from each other. Similarly, when q is 2 or 3, the groups represented by A are contained in one molecule of the compound represented by the general formula (7). 1 The groups represented by the formula (7) may be the same or different from each other. When r is 2 or 3, a plurality of A 2 The groups represented by the following formula (I) may be the same or different from each other.

[0105] Specific examples of the compound represented by the above general formula (7) are not particularly limited, but include, for example, A 2 is a group containing a primary amino group having an active hydrogen atom and / or a secondary amino group having an active hydrogen atom, such as 3-aminopropyldimethylmethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropylmethyldiethoxysilane, and 3-aminopropyltriethoxysilane. 2 Compounds having a 3-aminopropyl group; 4-aminobutyldimethylmethoxysilane, 4-aminobutylmethyldimethoxysilane, 4-aminobutyltrimethoxysilane, 4-aminobutyldimethylethoxysilane, 4-aminobutylmethyldiethoxysilane, 4-aminobutyltriethoxysilane, etc. 2Compounds having a 4-aminobutyl group; 3-(2-aminoethylamino)propyldimethylmethoxysilane, 3-(2-aminoethylamino)propylmethyldimethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-(2-aminoethylamino)propyldimethylethoxysilane, 3-(2-aminoethylamino)propylmethyldiethoxysilane, 3-(2-aminoethylamino)propyltriethoxysilane, etc. 2 Examples of the aryl group include compounds having a 3-(2-aminoethylamino)propyl group.

[0106] In addition, A in the general formula (7) 2 is a group other than a group containing a primary amino group having an active hydrogen atom and / or a secondary amino group having an active hydrogen atom, such as 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropylmethyldimethoxysilane, 3-dimethylaminopropyldimethylmethoxysilane, 3-dimethylaminopropyltriethoxysilane, 3-dimethylaminopropylmethyldiethoxysilane, and 3-dimethylaminopropyldimethylethoxysilane. 2 Compounds having a 3-dimethylaminopropyl group; 3-diethylaminopropyl trimethoxysilane, 3-diethylaminopropyl methyl dimethoxysilane, 3-diethylaminopropyl dimethyl methoxysilane, 3-diethylaminopropyl triethoxysilane, 3-diethylaminopropyl methyl diethoxysilane, 3-diethylaminopropyl dimethyl ethoxysilane, etc. 2 Compounds having a 3-diethylaminopropyl group; such as 3-dipropylaminopropyltrimethoxysilane, 3-dipropylaminopropylmethyldimethoxysilane, 3-dipropylaminopropyldimethylmethoxysilane, 3-dipropylaminopropyltriethoxysilane, 3-dipropylaminopropylmethyldiethoxysilane, and 3-dipropylaminopropyldimethylethoxysilane. 2Compounds having a 3-dipropylaminopropyl group; such as 3-dibutylaminopropyltrimethoxysilane, 3-dibutylaminopropylmethyldimethoxysilane, 3-dibutylaminopropyldimethylmethoxysilane, 3-dibutylaminopropyltriethoxysilane, 3-dibutylaminopropylmethyldiethoxysilane, and 3-dibutylaminopropyldimethylethoxysilane. 2 Compounds having a 3-dibutylaminopropyl group; 3-phenylmethylaminopropyl trimethoxysilane, 3-phenylmethylaminopropyl methyl dimethoxysilane, 3-phenylmethylaminopropyl dimethyl methoxysilane, 3-phenylmethylaminopropyl triethoxysilane, 3-phenylmethylaminopropyl methyl diethoxysilane, 3-phenylmethylaminopropyl dimethyl ethoxysilane, etc. 2 Compounds having a 3-phenylmethylaminopropyl group; 3-(4-methylpiperazinyl)propyltrimethoxysilane, 3-(4-methylpiperazinyl)propylmethyldimethoxysilane, 3-(4-methylpiperazinyl)propyldimethylmethoxysilane, 3-(4-methylpiperazinyl)propyltriethoxysilane, 3-(4-methylpiperazinyl)propylmethyldiethoxysilane, 3-(4-methylpiperazinyl)propyldimethylethoxysilane, etc. 2 as a compound having a 3-(4-methylpiperazinyl)propyl group;

[0107] A such as N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane, and N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane 2Compounds having an N,N-bis(trimethylsilyl)aminopropyl group; N,N-bis(triethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(triethylsilyl)aminopropylmethyldimethoxysilane, N,N-bis(triethylsilyl)aminopropylmethyldiethoxysilane, etc. 2 Compounds having an N,N-bis(triethylsilyl)aminopropyl group; N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, etc. 2 Examples of the compound include a compound having an N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropyl group.

[0108] As the hydrocarbyloxysilane compound, a compound represented by the following general formula (8) can also be suitably used. [ka] In the above general formula (8), A 3 is a hydrocarbyloxy group, R 17 represents a hydrocarbon group which may have a substituent; R 18 and R 19 each independently represents a hydrocarbon group which may have a substituent; R 18 and R 19 may be bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, and when such a ring structure is formed, they may form a ring structure together with the nitrogen atom to which they are bonded and a hetero atom other than the nitrogen atom to which they are bonded. s is an integer of 0 to 2.

[0109] A in the above general formula (8) 3 is a hydrocarbyloxy group, and examples thereof include alkoxy groups such as methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, and tert-butoxy group; alkenyloxy groups such as vinyloxy group and allyloxy group; aryloxy groups such as phenoxy group and naphthoxy group; aralkyloxy groups such as benzyloxy group; etc. Among these, from the viewpoint of reactivity, alkoxy groups and aryloxy groups are preferred, alkoxy groups are more preferred, and methoxy and ethoxy groups are particularly preferred.

[0110] In the above general formula (8), s (i.e., A 3 The number of groups represented by the formula (s) is an integer of 0 to 2, and it is preferable that s is 2. When s in the formula (8) is 2, two A groups are contained in one molecule of the compound represented by the formula (8). 3 The groups represented by the following formula (I) may be the same or different from each other.

[0111] In the above general formula (8), R 17 R represents a hydrocarbon group which may have a substituent. 17 The hydrocarbon group which can be is not particularly limited, but includes alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; alkenyl groups such as vinyl and allyl; alkynyl groups such as ethynyl and propynyl; aryl groups such as phenyl and naphthyl; and aralkyl groups such as benzyl. Among these, alkyl and aryl groups are preferred, alkyl groups are more preferred, and methyl and ethyl groups are particularly preferred. In addition, R 17The hydrocarbon group represented by the formula (8) may have a substituent other than the hydrocarbon group, and the substituent is not particularly limited, but may include a carbonyl group-containing group such as a carboxyl group, an acid anhydride group, a hydrocarbylcarbonyl group, an alkoxycarbonyl group, and an acyloxy group, an epoxy group, an oxy group, a cyano group, an amino group, and a halogen group. When s in the formula (8) is 0, two R 17 The groups represented by the following formula (I) may be the same or different from each other.

[0112] In the above general formula (8), R 18 and R 19 each independently represents a hydrocarbon group which may have a substituent; R 18 and R 19 may be bonded to each other to form a ring structure, and may form a ring structure together with the nitrogen atom to which they are bonded. In addition, when they form a ring structure, they may form a ring structure together with the nitrogen atom to which they are bonded and a hetero atom other than the nitrogen atom to which they are bonded. 18 and R 19 When they do not bond to each other, R 18 and R 19 The hydrocarbon group which can be is not particularly limited, but includes alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; alkenyl groups such as vinyl and allyl; alkynyl groups such as ethynyl and propynyl; aryl groups such as phenyl and naphthyl; and aralkyl groups such as benzyl. Among these, alkyl and aryl groups are preferred, alkyl groups are more preferred, and methyl and ethyl groups are particularly preferred. In addition, R 18 and R 19 When they are bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, R 18 and R 19The divalent hydrocarbon group formed by bonding is not particularly limited, but examples thereof include alkylene groups such as an n-butylene group (when these form a 1-pyrrolidine group together with the nitrogen atom to which they are bonded in general formula (8)) and an n-pentylene group (when they form a 1-piperidine group), and a butadienylene group (when they form a 1-pyrrole group). In addition, R 18 and R 19 When they are bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, the ring structure is preferably a 4- to 8-membered ring structure.

[0113] Also, R 18 and R 19 The hydrocarbon group represented by the formula (I) may have a substituent other than the hydrocarbon group, regardless of whether a ring structure is formed or not, and the substituent is not particularly limited, and examples of the substituent include a carbonyl group-containing group such as a carboxyl group, an acid anhydride group, a hydrocarbylcarbonyl group, an alkoxycarbonyl group, and an acyloxy group, an epoxy group, an oxy group, a cyano group, an amino group, and a halogen group. 18 and R 19 When they are bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, the atoms forming the ring structure may include heteroatoms other than carbon atoms and the nitrogen atom to which they are bonded, and examples of such heteroatoms include nitrogen atoms and oxygen atoms.

[0114] Particularly preferred compounds represented by the above general formula (8) are 18 and R 19 and the like, in which the hydrocarbon groups represented by the following formula (9) are bonded to each other to form a piperazine ring structure together with the nitrogen atom to which they are bonded. More specifically, the compound represented by the following general formula (9) is particularly preferred. By using a compound represented by the general formula (8) having such a structure, the obtained cross-linked rubber product can be one that has particularly improved fuel economy. [ka] In the above general formula (9), A 3 , R 17 , and s are the same as those in the above general formula (8), R 20 represents a hydrocarbon group.

[0115] R in the above general formula (9) 20 R represents a hydrocarbon group. 20 The possible hydrocarbon groups are not particularly limited, but include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; alkenyl groups such as vinyl and allyl; alkynyl groups such as ethynyl and propynyl; aryl groups such as phenyl and naphthyl; and aralkyl groups such as benzyl. Among these, alkyl and aryl groups are preferred, alkyl groups are more preferred, and methyl groups are particularly preferred.

[0116] Specific examples of the compound represented by the general formula (8) include 2,2-dimethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, 2,2-diethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, 2,2-dimethoxy-8-(N,N-diethylamino)methyl-1,6-dioxa-2-silacyclooctane, 2-methoxy-2-methyl-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, etc. These compounds represented by the general formula (8) may be used alone or in combination of two or more.

[0117] The amount of the hydrocarbyloxysilane compound used is not particularly limited, but is preferably 0.1 to 5 mol, more preferably 0.2 to 2 mol, and even more preferably 0.4 to 1.5 mol, per mol of the active end of the conjugated diene polymer chain having an active end obtained in the first step. By setting the amount of the hydrocarbyloxysilane compound used within the above range, the obtained cross-linked rubber product can have improved fuel economy.

[0118] The method of reacting the hydrocarbyloxysilane compound with the conjugated diene polymer chain reacted with the polyorganosiloxane represented by the general formula (1) after the second step described above is not particularly limited, but may include a method of mixing them in an inert solvent in which each of them can be dissolved. The inert solvent used in this case may be the inert solvent described above. In addition, in this case, it is preferable to add the hydrocarbyloxysilane compound to the reaction solution used in the second step described above to react the polyorganosiloxane represented by the general formula (1) with the conjugated diene polymer chain having an active terminal, which is simple and preferable. In addition, in this case, it is preferable to dissolve the hydrocarbyloxysilane compound in an inert solvent and add it to the polymerization system, and the solution concentration is preferably in the range of 1 to 50% by weight. The reaction temperature is not particularly limited, but is usually 0 to 120°C, and the reaction time is not particularly limited, but is usually 1 minute to 1 hour.

[0119] And, even in the case of reacting hydrocarbyloxysilane compounds, it is preferable to add a polymerization terminator such as alcohols such as methanol, ethanol and isopropanol or water after reacting the hydrocarbyloxysilane compounds to deactivate the unreacted active terminals.And, in the same manner as above, an antiaging agent such as a phenolic stabilizer, a phosphorus stabilizer, a sulfur stabilizer, a crumbing agent, and a scale inhibitor are added to the reaction solution, and then the inert solvent is separated from the reaction solution by direct drying or steam stripping, etc., to recover the modified conjugated diene rubber.Note that before separating the inert solvent from the reaction solution, an extender oil may be mixed into the polymerization solution, and the modified conjugated diene rubber may be recovered as an oil-extended rubber.

[0120] <Rubber composition> The rubber composition of the present invention is a composition containing silica in addition to a rubber component containing the modified conjugated diene rubber obtained by the above-mentioned production method of the present invention.

[0121] The rubber composition of the present invention may contain rubbers other than the modified conjugated diene rubber obtained by the production method of the present invention described above. Examples of other rubbers include natural rubber (which may be modified natural rubber such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), highly purified natural rubber (UPNR), and grafted natural rubber), polyisoprene rubber, emulsion-polymerized styrene-butadiene copolymer rubber, solution-polymerized styrene-butadiene copolymer rubber, polybutadiene rubber (which may be high cis-BR or low cis BR. Also, it may be polybutadiene rubber containing crystal fibers made of 1,2-polybutadiene polymer), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, acrylonitrile-styrene-butadiene copolymer rubber, butyl rubber (IIR), ethylene-propylene copolymer, chloroprene rubber, nitrile chloroprene rubber, and nitrile isoprene rubber, which are other than the modified conjugated diene rubber obtained by the above-mentioned production method of the present invention. Among these, natural rubber, polyisoprene rubber, polybutadiene rubber, and solution-polymerized styrene-butadiene copolymer rubber are preferred. These rubbers can be used alone or in combination of two or more, such as natural rubber and polybutadiene rubber, or natural rubber and styrene-butadiene copolymer rubber.

[0122] In the rubber composition of the present invention, the modified conjugated diene rubber obtained by the production method of the present invention preferably accounts for 10 to 100% by weight, and particularly preferably 50 to 100% by weight, of the rubber component in the rubber composition. By including the modified conjugated diene rubber obtained by the production method of the present invention in the rubber component in such a ratio, a cross-linked rubber product having improved fuel economy can be obtained.

[0123] Examples of silica used in the present invention include dry process white carbon, wet process white carbon, colloidal silica, precipitated silica, calcium silicate, and aluminum silicate. Among these, wet process white carbon containing hydrous silicic acid as a main component is preferable. Carbon-silica dual phase filler in which silica is supported on the surface of carbon black may also be used. These silicas may be used alone or in combination of two or more kinds. The nitrogen adsorption specific surface area of ​​the silica used (measured by the BET method in accordance with ASTM D3037-81) is preferably 20 to 400 m. 2 / g, more preferably 50 to 220m 2 / g, particularly preferably 80 to 170m 2 The pH of the silica is preferably 5 to 10.

[0124] The silica used in the present invention has a dibutyl phthalate (DBP) absorption value preferably in the range of about 100 to about 400, particularly preferably in the range of about 150 to about 300.

[0125] The silica used in the present invention preferably has an average ultimate particle size in the range of 0.01 to 0.05 μm as measured by electron microscopy, but the average ultimate particle size of the silica is not limited to this range and may be smaller or larger.

[0126] The silica used in the present invention may be, for example, various commercially available silicas, such as Hi-Sil, 210, Hi-Sil 233, and Hi-Sil 243LD manufactured by PPG Industries, Zeosil 1115MP, Zeosil 1165MP, Zeosil 165GR, and Zeosil Premium 200MP manufactured by Solvay, and ULTRASIL VN2 and ULTRASIL VN3 manufactured by Evonik.

[0127] The amount of silica blended in the rubber composition of the present invention is preferably 10 to 250 parts by weight, more preferably 15 to 150 parts by weight, and further preferably 20 to 130 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition. By making the amount of silica blended within the above range, the fuel economy of the obtained cross-linked rubber product can be further improved.

[0128] The rubber composition of the present invention may further contain a silane coupling agent from the viewpoint of further improving fuel economy. The silane coupling agent is not particularly limited, and various silane coupling agents can be used, but in the present invention, sulfide-based, mercapto-based, protected mercapto-based (e.g., those having a carbonylthio group), thiocyanate-based, vinyl-based, amino-based, methacrylate-based, glycidoxy-based, nitro-based, epoxy-based or chloro-based silane coupling agents can be preferably used. Specific examples of the silane coupling agent include bis(3-(triethoxysilyl)propyl) disulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(3-(triethoxysilyl)propyl) tetrasulfide, γ-mercaptopropyltriethoxysilane, 3-[ ethoxybis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silyl]-1-propanethiol, 3-octanoylthio-1-propyl-triethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, γ-trimethoxysilylpropyl benzothiazyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazole tetrasulfide, 3-thiocyanatepropyl triethoxysilane, vinyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane, 3-trimethoxysilylpropyl methacrylate monosulfide, γ-glycidoxypropyl triethoxysilane, 3-nitropropyl trimethoxysilane, β-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, and 3-chloropropyl trimethoxysilane. In addition, NXT-Z100, NXT-Z30, NXT-Z45, NXT-Z60, NXT-Z45, NXT manufactured by Momentive Performance Materials, Si69, Si75, VP Si363 manufactured by Evonik, etc. can also be used. These silane coupling agents can be used alone or in combination of two or more. In addition, one or more of these can be oligomerized in advance and used in the oligomerized state.The amount of the silane coupling agent to be added is preferably 0.1 to 30 parts by weight, and more preferably 1 to 15 parts by weight, based on 100 parts by weight of silica.

[0129] The rubber composition of the present invention may further contain carbon black such as furnace black, acetylene black, thermal black, channel black, and graphite. Among these, furnace black is preferred. These carbon blacks may be used alone or in combination of two or more. The amount of carbon black is usually 120 parts by weight or less per 100 parts by weight of the rubber component in the rubber composition.

[0130] The method for adding silica to the rubber component containing the modified conjugated diene rubber obtained by the production method of the present invention is not particularly limited, and may include a method of adding silica to a solid rubber component and kneading it (dry kneading method) or a method of adding silica to a solution containing a conjugated diene rubber and coagulating / drying it (wet kneading method).

[0131] In addition, the rubber composition of the present invention preferably further contains a crosslinking agent. Examples of the crosslinking agent include sulfur-containing compounds such as sulfur and sulfur halides, organic peroxides, quinone dioximes, organic polyamine compounds, and alkylphenol resins having a methylol group. Among these, sulfur is preferably used. The amount of the crosslinking agent is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition.

[0132] In addition to the above components, the rubber composition of the present invention may contain a required amount of compounding agents such as crosslinking accelerators, crosslinking activators, antiaging agents, fillers (excluding the above silica and carbon black), activators, process oils, plasticizers, lubricants, compatibilizers, and surfactants according to a conventional method. Examples of process oils include paraffinic, aromatic, and naphthenic petroleum-based softeners, vegetable softeners, synthetic softeners using plant-derived resources, and fatty acids. When using a petroleum-based softener, it is preferable that the content of polycyclic aromatics extracted by the IP346 method (the test method of THE INSTITUTE PETROLEUM in the UK) is less than 3%.

[0133] When sulfur or a sulfur-containing compound is used as the crosslinking agent, it is preferable to use a crosslinking accelerator and a crosslinking activator in combination. Examples of the crosslinking accelerator include sulfenamide crosslinking accelerators, guanidine crosslinking accelerators, thiourea crosslinking accelerators, thiazole crosslinking accelerators, thiuram crosslinking accelerators, dithiocarbamic acid crosslinking accelerators, and xanthogenic acid crosslinking accelerators. Among these, those containing sulfenamide crosslinking accelerators are preferable. These crosslinking accelerators are used alone or in combination of two or more. The amount of the crosslinking accelerator is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition.

[0134] Examples of the crosslinking activator include higher fatty acids such as stearic acid, zinc oxide, etc. These crosslinking activators may be used alone or in combination of two or more. The amount of the crosslinking activator is preferably 0.05 to 20 parts by weight, particularly preferably 0.5 to 15 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition.

[0135] In addition, the rubber composition of the present invention may contain a resin in addition to the rubber component. By compounding a resin, it is possible to impart adhesion to the rubber composition or to increase the dispersibility of the filler in the rubber composition. As a result, it is expected that the wet grip property and abrasion resistance of the obtained crosslinked rubber product will be improved. In addition, as an effect similar to that of a plasticizer, it is also possible to improve the processability of the rubber composition. Examples of resins include C5 petroleum resins, C5 / C9 petroleum resins, C9 petroleum resins, dicyclopentadiene resins, terpene resins, terpene phenol resins, aromatic modified terpene resins, alkylphenol-acetylene resins, rosin resins, rosin ester resins, indene resins, C9 resins containing indene, α-methylstyrene-indene copolymer resins, coumarone-indene resins, farnesene resins, and polylimonene resins. These resins may be modified or hydrogenated. These resins may be used alone or in combination of two or more. The amount of the resin to be mixed is preferably 25 parts by weight or less based on 100 parts by weight of the rubber component in the rubber composition.

[0136] To obtain the rubber composition of the present invention, each component may be kneaded according to a conventional method. For example, the components other than the heat-unstable components such as the crosslinking agent and the crosslinking accelerator are kneaded with the conjugated diene rubber, and then the heat-unstable components such as the crosslinking agent and the crosslinking accelerator are mixed with the kneaded mixture to obtain the desired composition. The kneading temperature of the components other than the heat-unstable components and the conjugated diene rubber is preferably 80 to 200°C, more preferably 120 to 180°C, and the kneading time is preferably 30 seconds to 30 minutes. In addition, the kneaded mixture is usually mixed with the heat-unstable components after cooling to 100°C or less, preferably 80°C or less.

[0137] <Rubber cross-linked products> The cross-linked rubber product of the present invention is obtained by cross-linking the above-mentioned rubber composition of the present invention. The cross-linked rubber product of the present invention can be produced by using the rubber composition of the present invention, for example, molding the rubber composition into a desired shape using a molding machine such as an extruder, an injection molding machine, a compressor, or a roll, and heating the composition to cause a cross-linking reaction and fix the shape as a cross-linked rubber product. In this case, the cross-linking may be carried out after molding in advance or simultaneously with molding. The molding temperature is usually 10 to 200°C, preferably 25 to 120°C. The cross-linking temperature is usually 100 to 200°C, preferably 130 to 190°C, and the cross-linking time is usually 1 minute to 24 hours, preferably 2 minutes to 12 hours, and particularly preferably 3 minutes to 6 hours.

[0138] Depending on the shape, size, etc. of the cross-linked rubber product, even if the surface is cross-linked, the inside may not be sufficiently cross-linked, so secondary cross-linking may be performed by further heating.

[0139] The heating method may be appropriately selected from among methods commonly used for crosslinking rubber, such as press heating, steam heating, oven heating, and hot air heating.

[0140] The cross-linked rubber product of the present invention thus obtained has good fuel economy because it is obtained by using the modified conjugated diene rubber obtained by the production method of the present invention described above, and can be used for various applications, making use of its properties, for example, in tires, as materials for various tire parts such as cap tread, base tread, carcass, sidewall, bead portion, etc.; materials for hoses, belts, mats, anti-vibration rubber, and various other industrial products; impact resistance improvers for resins; resin film cushioning agents; shoe soles; rubber shoes; golf balls; toys; etc. In particular, since the cross-linked rubber product of the present invention has good fuel economy, it can be suitably used as a tire material, particularly a material for fuel-efficient tires, and is most suitable for tread applications. EXAMPLES

[0141] The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In the following, "parts" are by weight unless otherwise specified. Tests and evaluations were performed according to the following.

[0142] [Peak top molecular weight (Mp), weight average molecular weight (Mw), and molecular weight distribution (Mw / Mn)] The peak top molecular weight (Mp), weight average molecular weight (Mw), and molecular weight distribution (Mw / Mn) of the modified conjugated diene polymer were determined based on a chart obtained by gel permeation chromatography (GPC) based on the molecular weight converted into polystyrene. The specific measurement conditions for gel permeation chromatography were as follows: Measuring instrument: High-performance liquid chromatograph (Tosoh Corporation, product name "HLC-8320") Column: Two polystyrene columns manufactured by Tosoh Corporation, trade name "GMH-HR-H", were connected in series. Detector: Differential refractometer Eluent: Tetrahydrofuran Column temperature: 40℃

[0143] [Styrene unit content, vinyl bond content] The styrene unit content and vinyl bond content are 1 Measurements were performed by H-NMR.

[0144] [Mooney Viscosity] Measurements were made using a Mooney viscometer (Shimadzu Corporation) in accordance with JIS K6300-1 (2013). Note that for rubber that was not made into oil-extended rubber, the Mooney viscosity was measured in an un-oil-extended state.

[0145] [Maximum power load of the mixer] In the polymerization and modification reactions in the production of modified conjugated diene polymers, the power load of the agitator used in the polymerization and modification reactions was continuously recorded, and the maximum power load, which was the maximum power load, was determined to evaluate the production efficiency in the modification reaction. The maximum power load is expressed as an index with the measured value of Comparative Example 1 set to 100 for Examples 1 to 10 and Comparative Example 1, an index with the measured value of Comparative Example 2 set to 100 for Examples 11 to 13 and Comparative Example 2, an index with the measured value of Comparative Example 3 set to 100 for Examples 14, 15 and Comparative Example 3, and an index with the measured value of Reference Example 1 set to 100 for Reference Examples 1 to 3. The smaller the index, the lower the power load is required to produce a modified conjugated diene polymer, and the more energy efficient it is. Furthermore, it is possible to produce a higher polymer concentration while realizing high energy efficiency, and therefore it can be determined that high productivity can be realized.

[0146] [Ratio of multi-branched bodies] In the elution curve obtained by gel permeation chromatography of the modified conjugated diene polymer under the above conditions, the area ratio of the peak portion having a peak top molecular weight 1.8 times or more of the peak top molecular weight of the smallest molecular weight peak relative to the total elution area was taken as the area ratio of the peak portion derived from the multi-branched body having 2 or more branches, and this area ratio was calculated as the ratio of the multi-branched body. The ratio of the multi-branched body is shown as an index with the measured value of Comparative Example 1 set to 100 for Examples 1 to 10 and Comparative Example 1, with the measured value of Comparative Example 2 set to 100 for Examples 11 to 13 and Comparative Example 2, with the measured value of Comparative Example 3 set to 100 for Examples 14, 15 and Comparative Example 3, and with the measured value of Reference Example 1 set to 100 for Reference Examples 1 to 3. It can be judged that the smaller this index is, the easier the bale molding is, and the better the productivity is.

[0147] [Fuel economy of cross-linked rubber] The low heat build-up property of the cross-linked rubber product was evaluated by measuring tan δ at 60°C using a test piece of the cross-linked rubber product with a length of 50 mm, a width of 12.7 mm, and a thickness of 2 mm, under conditions of a dynamic strain of 2.0% and 10 Hz, using ARES-G2 (manufactured by TA Instruments). The values ​​of tan δ are shown as indexes with the measured value of Comparative Example 1 set to 100 for Examples 1 to 10 and Comparative Example 1, with the measured value of Comparative Example 2 set to 100 for Examples 11 to 13 and Comparative Example 2, with the measured value of Comparative Example 3 set to 100 for Examples 14 and 15 and Comparative Example 3, and with the measured value of Reference Example 1 set to 100 for Reference Examples 1 to 3. The smaller the index, the better the fuel economy.

[0148] Example 1 (Production of polymer block (A)) Into a nitrogen-substituted vessel, 218.1 parts of cyclohexane, 7.5 parts of styrene, and 0.3 parts of tetramethylethylenediamine were added, and the temperature inside the vessel was adjusted to 50°C. Next, 1.64 parts of n-butyllithium were added, and 92.5 parts of isoprene were added over 80 minutes. The mixture was then reacted for 15 minutes to obtain a solution containing a polymer block (A) having an active terminal. The weight average molecular weight (Mw) of this polymer block (A) was 6,500, the molecular weight distribution (Mw / Mn) was 1.10, the styrene unit content was 7.5%, the isoprene unit content was 92.5%, and the vinyl bond content was 7.0%.

[0149] (Production of modified conjugated diene polymer) In an autoclave equipped with a stirrer, 455.6 parts of cyclohexane, 36.0 parts of styrene, 24.0 parts of 1,3-butadiene, and 0.026 parts of tetramethylethylenediamine were charged under a nitrogen atmosphere. In order to detoxify impurities that act to deactivate the polymerization, normal butyl lithium was added to the autoclave as a scavenger, and then 5.3 parts of the obtained solution containing the polymer block (A) having an active terminal (the amount of the polymer block (A) used was 1.6 parts) was added, and polymerization was started at 40°C. 20 minutes after the start of polymerization, 3.8 parts of styrene and 21.3 parts of 1,3-butadiene were continuously added over 20 minutes. Then, 2.3 parts of styrene and 12.8 parts of 1,3-butadiene were continuously added over 30 minutes. The maximum temperature during the polymerization reaction was 70°C. After a series of continuous additions, the mixture was stirred for 30 minutes, and after it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, the addition of polyorganosiloxane represented by the following formula (10) was started. The polyorganosiloxane was used in the state of a xylene solution with a concentration of 40% by weight, and was added continuously and at a constant speed for 5 minutes from the start of addition under stirring with a stirrer. The total amount of polyorganosiloxane added was 0.129 parts (equivalent to 0.450 moles per mole of n-butyllithium used, calculated as epoxy groups in the polyorganosiloxane). Then, under stirring with a stirrer, a modification reaction was carried out for 30 minutes from the start of addition of the polyorganosiloxane. Thereafter, methanol was added as a polymerization terminator in an amount equivalent to twice the moles of n-butyllithium used to obtain a solution containing a modified conjugated diene polymer. In Example 1, the concentration of the modified conjugated diene polymer in the solution containing the modified conjugated diene polymer (final polymer concentration) was 18% by weight. Then, 0.20 parts of Irganox 1520L (manufactured by Ciba Specialty Chemicals) was added to this solution as an anti-aging agent per 100 parts of the modified conjugated diene polymer, and then 25 parts of process oil (manufactured by ENEOS Corporation, product name: Aromax T-DAE) was added as an extender oil to the modified conjugated diene polymer and stirred, after which the solvent was removed by steam stripping and a solid modified conjugated diene polymer was obtained by hot air drying.The styrene unit amount, vinyl bond amount, peak top molecular weight (Mp), weight average molecular weight (Mw), molecular weight distribution (Mw / Mn), Mooney viscosity, and content ratio of multi-branched bodies of the obtained modified conjugated diene polymer, as well as the maximum power load of the stirrer during the modification reaction with polyorganosiloxane, were measured. The results are shown in Table 1. [ka]

[0150] (Production of rubber composition and cross-linked rubber product) In a 250 ml Brabender mixer, 70 parts of the modified conjugated diene polymer obtained above (amount as polymer excluding extender oil) and 30 parts of butadiene rubber (manufactured by Zeon Corporation, product name "Nipol BR1220") were masticated for 30 seconds, and then 50 parts of silica (manufactured by Solvay, product name "Zeosil 1165MP"), 10 parts of process oil (manufactured by JX Nippon Oil & Energy Corporation, product name "Aromax T-DAE"), and 6.0 parts of a silane coupling agent (manufactured by Evonik, product name "Si69") were added and kneaded for 1.5 minutes at a starting temperature of 110°C, and the silica (manufactured by Solvay, product name "Zeosil To the mixture were added 25 parts of "N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Nocrac 6C"), 3.0 parts of zinc oxide, 2.0 parts of stearic acid, and 2.0 parts of an antioxidant: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Nocrac 6C"), and the mixture was further kneaded for 2.5 minutes, and the kneaded product was discharged from the mixer. The temperature of the kneaded product at the end of kneading was 150°C. After cooling to room temperature, the kneaded product was kneaded again in the Brabender type mixer with an initial temperature of 110°C for 3 minutes, and the kneaded product was discharged from the mixer. Next, 1.50 parts of sulfur, 1.8 parts of N-cyclohexyl-2-benzothiazolylsulfenamide (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Noccela CZ-G"), and 1.5 parts of 1,3-diphenylguanidine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Noccela D") were added to the obtained kneaded product and kneaded with an open roll at 50 ° C. to obtain a rubber composition. The obtained rubber composition was then molded into a sheet with an open roll at 50 ° C., and the obtained sheet-shaped rubber composition was press-crosslinked at 160 ° C. for 20 minutes to obtain a test piece of the rubber crosslinked product, and the obtained rubber crosslinked product was used to evaluate fuel economy. The results are shown in Table 1.

[0151] Example 2 A modified conjugated diene polymer and a cross-linked rubber were obtained and evaluated in the same manner as in Example 1, except that the polyorganosiloxane represented by the above formula (10) (40 wt% xylene solution) was added continuously and at a constant speed under stirring with a stirrer for 14 minutes from the start of addition. The results are shown in Table 1.

[0152] Example 3 A modified conjugated diene polymer was obtained in the same manner as in Example 1, except that the polyorganosiloxane represented by the above formula (10) (40 wt% xylene solution) was added continuously and at a constant speed under stirring with a stirrer for 20 minutes from the start of addition, and the amount of process oil added was changed to 20 parts per 100 parts of the modified conjugated diene polymer. A rubber cross-linked product was obtained in the same manner as in Example 1, except that the amount of process oil added during the production of the rubber composition and the cross-linked rubber product was changed to 13.5 parts, and evaluation was performed in the same manner. The results are shown in Table 1.

[0153] Example 4 The polyorganosiloxane represented by the above formula (10) (40 wt% xylene solution) was added continuously and at a constant speed under stirring with a stirrer for 33 minutes from the start of addition, and the modification reaction was carried out for 35 minutes from the start of addition of the polyorganosiloxane. A modified conjugated diene polymer and a cross-linked rubber were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0154] Example 5 A modified conjugated diene polymer was obtained in the same manner as in Example 1, except that the amount of tetramethylethylenediamine added and the amount of the solution containing the polymer block (A) having an active end were changed, and the polyorganosiloxane represented by the above formula (10) (40 wt % xylene solution) was added in three separate times. Specifically, 0.027 parts of tetramethylethylenediamine and 5.7 parts of a solution containing a polymer block (A) having an active terminal (the amount of polymer block (A) used was 1.72 parts) were charged, and the polymerization reaction was carried out in the same manner as in Example 1. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 0.047 parts of polyorganosiloxane (40% by weight concentration xylene solution) were added (1st stage addition) within 1 minute under stirring with a stirrer (equivalent to 0.150 moles per mole of n-butyllithium used in terms of epoxy groups in polyorganosiloxane), and a modification reaction was carried out for 10 minutes under stirring with a stirrer. Next, after the modification reaction for 10 minutes, 0.047 parts of polyorganosiloxane (40% by weight concentration xylene solution) were added within 1 minute under stirring with a stirrer (2nd stage addition), and a modification reaction was carried out for 10 minutes under stirring with a stirrer. After the modification reaction for 10 minutes, 0.047 parts of polyorganosiloxane (40% by weight xylene solution) was added within 1 minute under stirring by a stirrer (third stage addition), and the modification reaction was carried out under stirring by a stirrer. Then, the modification reaction was carried out for 40 minutes from the start of the addition of polyorganosiloxane under stirring by a stirrer. Then, except that the amount of tetramethylethylenediamine and the amount of the solution containing the polymer block (A) having an active terminal were changed, and the method of adding the polyorganosiloxane (40% by weight xylene solution) was changed as described above, a modified conjugated diene polymer and a cross-linked rubber were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0155] Example 6 A modified conjugated diene polymer was obtained in the same manner as in Example 1, except that the amount of tetramethylethylenediamine added was changed and the polyorganosiloxane represented by the above formula (10) (40% by weight xylene solution) was added in two separate portions. Specifically, the polymerization reaction was carried out in the same manner as in Example 1, except that 0.025 parts of tetramethylethylenediamine were added, and after confirming that the polymerization conversion rate was in the range of 95% to 100%, 0.064 parts of polyorganosiloxane (40% by weight xylene solution) (equivalent to 0.225 moles per mole of n-butyllithium used, calculated as epoxy groups in polyorganosiloxane) were added (first-stage addition) within 1 minute under stirring by a stirrer, and a modification reaction was carried out for 10 minutes under stirring by a stirrer. Next, after the modification reaction for 10 minutes, 0.064 parts of polyorganosiloxane (40% by weight xylene solution) were added (second-stage addition) within 1 minute under stirring by a stirrer, and a modification reaction was carried out under stirring by a stirrer. Then, a modification reaction was carried out for 30 minutes from the start of addition of polyorganosiloxane under stirring by a stirrer. Then, except for changing the amount of tetramethylethylenediamine added and changing the method of adding polyorganosiloxane (40% by weight xylene solution) as described above, a modified conjugated diene polymer and a cross-linked rubber were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0156] Example 7 The amount of tetramethylethylenediamine added was changed to 0.026 parts, and the amount of polyorganosiloxane (40% by weight xylene solution) added in the first stage was 0.079 parts (equivalent to 0.275 moles per mole of n-butyllithium used in terms of epoxy groups in polyorganosiloxane), and the amount of polyorganosiloxane (40% by weight xylene solution) added in the second stage was 0.050 parts (equivalent to 0.175 moles per mole of n-butyllithium used in terms of epoxy groups in polyorganosiloxane), except that the modified conjugated diene polymer and the cross-linked rubber were obtained in the same manner as in Example 6 and were evaluated in the same manner. The results are shown in Table 1.

[0157] Example 8 The amount of tetramethylethylenediamine added was changed to 0.029 parts, the amount of the solution containing the polymer block (A) having an active terminal was changed to 6.3 parts (the amount of the polymer block (A) used was 1.9 parts), and the amount of the polyorganosiloxane (40% by weight xylene solution) added in the first stage was changed to 0.102 parts (equivalent to 0.300 moles per mole of n-butyllithium used in terms of epoxy groups in the polyorganosiloxane), and the amount of the polyorganosiloxane (40% by weight xylene solution) added in the second stage was changed to 0.051 parts (equivalent to 0.150 moles per mole of n-butyllithium used in terms of epoxy groups in the polyorganosiloxane), and the modified conjugated diene polymer and the cross-linked rubber were obtained in the same manner as in Example 6 and evaluated in the same manner. The results are shown in Table 1.

[0158] Example 9 A modified conjugated diene polymer and a cross-linked rubber were obtained and evaluated in the same manner as in Example 8, except that the amount of cyclohexane used as the solvent was changed to 426.3 parts. The results are shown in Table 1. In Example 9, the concentration of the modified conjugated diene polymer in the solution containing the modified conjugated diene polymer (final polymer concentration) was 19% by weight.

[0159] Example 10 A modified conjugated diene polymer and a cross-linked rubber were obtained and evaluated in the same manner as in Example 8, except that the amount of cyclohexane used as the solvent was changed to 400.0 parts. The results are shown in Table 1. In Example 10, the concentration of the modified conjugated diene polymer in the solution containing the modified conjugated diene polymer (final polymer concentration) was 20% by weight.

[0160] Comparative Example 1 A modified conjugated diene polymer was obtained in the same manner as in Example 6, except that the polyorganosiloxane represented by the above formula (10) (a xylene solution having a concentration of 40% by weight) was added all at once. Specifically, a polymerization reaction was carried out in the same manner as in Example 1, and after it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, a total amount of 0.129 parts (equivalent to 0.450 moles per mole of n-butyllithium used, calculated as the epoxy group in the polyorganosiloxane) of polyorganosiloxane (xylene solution with a concentration of 40% by weight) was added within 1 minute while stirring with a stirrer, and a modification reaction was carried out for 30 minutes while stirring with a stirrer. Then, except for changing the method of adding polyorganosiloxane (40% by weight xylene solution) as described above, a modified conjugated diene polymer and a cross-linked rubber were obtained and evaluated in the same manner as in Example 6. The results are shown in Table 1.

[0161] Example 11 (Production of modified conjugated diene polymer) In an autoclave equipped with a stirrer, 455.6 parts of cyclohexane, 16.0 parts of styrene, 44.0 parts of 1,3-butadiene, and 0.146 parts of tetramethylethylenediamine were charged under a nitrogen atmosphere. In order to detoxify impurities that act on deactivation of polymerization in advance, normal butyl lithium was added to the autoclave as a scavenger, and then 9.8 parts of the solution containing the polymer block (A) having an active terminal obtained in the above Example 1 (the amount of the polymer block (A) used was 2.96 parts) was added, and polymerization was started at 40 ° C. After 10 minutes had elapsed since the start of polymerization, 5.0 parts of styrene and 35.0 parts of 1,3-butadiene were continuously added over 40 minutes. The maximum temperature during the polymerization reaction was 70 ° C. After a series of continuous additions, the mixture was stirred for 20 minutes, and after it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, the addition of the polyorganosiloxane represented by the above formula (10) was started. Specifically, after confirming that the polymerization conversion rate was in the range of 95% to 100%, 0.119 parts of polyorganosiloxane (equivalent to 0.225 moles per mole of n-butyllithium used, calculated as epoxy groups in polyorganosiloxane) were added in a xylene solution of 40% by weight concentration within 1 minute under stirring with a stirrer (first-stage addition), and a modification reaction was carried out for 10 minutes under stirring with a stirrer. Next, after the modification reaction for 10 minutes, 0.119 parts of polyorganosiloxane were added in a xylene solution of 40% by weight concentration within 1 minute under stirring with a stirrer (second-stage addition), and a modification reaction was carried out under stirring with a stirrer. Then, a modification reaction was carried out for 30 minutes from the start of the addition of polyorganosiloxane under stirring with a stirrer. Then, as a polymerization terminator, methanol was added in an amount equivalent to twice the moles of n-butyllithium used to obtain a solution containing a modified conjugated diene-based polymer. In Example 11, the concentration of the modified conjugated diene polymer in the solution containing the modified conjugated diene polymer (final polymer concentration) was 18% by weight. Then, 0.20 parts of Irganox 1520L (manufactured by Ciba Specialty Chemicals) was added to this solution as an antiaging agent relative to 100 parts of the modified conjugated diene polymer, and the solvent was removed by steam stripping, and a solid modified conjugated diene polymer was obtained by hot air drying.The styrene unit amount, vinyl bond amount, peak top molecular weight (Mp), weight average molecular weight (Mw), molecular weight distribution (Mw / Mn), Mooney viscosity, and content ratio of multi-branched bodies of the obtained modified conjugated diene polymer, as well as the maximum power load of the stirrer during the modification reaction with polyorganosiloxane, were measured. The results are shown in Table 2.

[0162] (Production of rubber composition and cross-linked rubber product) A rubber composition and a cross-linked rubber product were prepared in the same manner as in Example 1, except that the modified conjugated diene polymer obtained above was used and the amount of process oil added during the production of the rubber composition and the cross-linked rubber product was changed to 25 parts, and the obtained cross-linked rubber product was used to evaluate fuel economy. The results are shown in Table 2.

[0163] Example 12 The second stage of polyorganosiloxane represented by the above formula (10) (40% by weight xylene solution) was added, and the modified reaction was carried out for 30 minutes under stirring with a stirrer. Then, 0.226 parts (corresponding to 1.00 mole per mole of n-butyl lithium used) of 2,2-dimethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane (compound represented by the above general formula (9)) as hydrocarbyl oxirane compound A was added in 50% by weight xylene solution under stirring with a stirrer within 1 minute, and the reaction was carried out for 15 minutes. The modified conjugated diene polymer and the crosslinked rubber were obtained in the same manner as in Example 11, and were evaluated in the same manner. The results are shown in Table 2.

[0164] Example 13 The second stage of polyorganosiloxane (40% by weight xylene solution) represented by the above formula (10) was added, and the modified reaction was carried out for 30 minutes under stirring by a stirrer. Further, 0.165 parts (corresponding to 1.00 mole per mole of n-butyl lithium used) of 3-(2-aminoethylamino)propyltrimethoxysilane (compound represented by the above general formula (7)) as hydrocarbyl oxirane compound B was added in a xylene solution of 50% by weight within 1 minute under stirring by a stirrer. The modified conjugated diene polymer and the crosslinked rubber were obtained in the same manner as in Example 11, and were evaluated in the same manner. The results are shown in Table 2.

[0165] Comparative Example 2 A modified conjugated diene polymer was obtained in the same manner as in Example 11, except that the polyorganosiloxane represented by the above formula (10) (a xylene solution having a concentration of 40% by weight) was added all at once. Specifically, a polymerization reaction was carried out in the same manner as in Example 11, and after it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, a total amount of 0.238 parts (equivalent to 0.450 moles per mole of n-butyllithium used, calculated as the epoxy group in the polyorganosiloxane) of polyorganosiloxane (xylene solution with a concentration of 40% by weight) was added within 1 minute while stirring with a stirrer, and a modification reaction was carried out for 20 minutes while stirring with a stirrer. Then, except for changing the method of adding polyorganosiloxane (40% by weight xylene solution) as described above, a modified conjugated diene polymer and a cross-linked rubber were obtained and evaluated in the same manner as in Example 11. The results are shown in Table 2.

[0166] Example 14 (Production of modified conjugated diene polymer) In an autoclave equipped with a stirrer, 500.4 parts of cyclohexane, 15.0 parts of styrene, 37.1 parts of 1,3-butadiene, and 0.016 parts of tetramethylethylenediamine were charged under a nitrogen atmosphere. In order to detoxify impurities that act on deactivation of polymerization in advance, normal butyl lithium was added to the autoclave as a scavenger, and then 8.8 parts of the solution containing the polymer block (A) having an active end obtained in the above Example 1 (the amount of the polymer block (A) used was 2.66 parts) was added, and polymerization was started at 55°C. 12 minutes after the start of polymerization, 3.3 parts of 1,3-butadiene were continuously added over 4 minutes. One minute later, 17.8 parts of 1,3-butadiene were continuously added over 17 minutes. Furthermore, 13.4 parts of 1,3-butadiene were continuously added over 18 minutes. Further, 13.4 parts of 1,3-butadiene were continuously added over 35 minutes. The maximum temperature during the polymerization reaction was 80°C. After a series of continuous additions, the mixture was stirred for 30 minutes, and after it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, 0.053 parts of tetramethylethylenediamine was added and stirred for 5 minutes. Then, 0.002 parts of 1,6-bis(trichlorosilyl)hexane was added and reacted for 10 minutes. Then, the addition of polyorganosiloxane represented by the above formula (10) was started. Specifically, 0.143 parts of polyorganosiloxane (equivalent to 0.300 moles per mole of n-butyllithium used, calculated as epoxy groups in polyorganosiloxane) was added in a xylene solution with a concentration of 40% by weight within 1 minute under stirring with a stirrer (first-stage addition), and the modification reaction was carried out for 10 minutes under stirring with a stirrer. Next, after 10 minutes of modification reaction, 0.143 parts of polyorganosiloxane was added in a 40% by weight xylene solution (second stage addition) within 1 minute under stirring by a stirrer, and modification reaction was carried out under stirring by a stirrer. Then, modification reaction was carried out for 30 minutes from the start of addition of polyorganosiloxane under stirring by a stirrer. Furthermore, 0.148 parts of hydrocarbyl oxirane compound B (corresponding to 1.00 mole per mole of n-butyl lithium used) was added in a 50% by weight xylene solution under stirring by a stirrer within 1 minute, and reaction was carried out for 15 minutes.Then, as a polymerization terminator, methanol was added in an amount equivalent to twice the molar amount of n-butyllithium used to obtain a solution containing a modified conjugated diene polymer. In Example 14, the concentration of the modified conjugated diene polymer in the solution containing the modified conjugated diene polymer (final polymer concentration) was 16.7% by weight. Then, as an antiaging agent, 0.20 parts of Irganox 1520L (manufactured by Ciba Specialty Chemicals) were added to this solution relative to 100 parts of the modified conjugated diene polymer, and 0.20 parts of Irganox 1076 (manufactured by Ciba Specialty Chemicals) were added relative to 100 parts of the modified conjugated diene polymer, and the solvent was removed by steam stripping, and a solid modified conjugated diene polymer was obtained by hot air drying. The styrene unit amount, vinyl bond amount, peak top molecular weight (Mp), weight average molecular weight (Mw), molecular weight distribution (Mw / Mn), Mooney viscosity, and content ratio of multi-branched bodies of the obtained modified conjugated diene polymer, as well as the maximum power load of the stirrer during the modification reaction with polyorganosiloxane, were measured. The results are shown in Table 3.

[0167] (Production of rubber composition and cross-linked rubber product) In a 250 ml Banbury mixer, 50 parts of natural rubber, 30 parts of the modified conjugated diene polymer obtained above, and 20 parts of butadiene rubber (manufactured by Nippon Zeon Co., Ltd., product name "Nipol BR1220") were masticated for 30 seconds. Next, 25 parts of silica (manufactured by Solvay, trade name "Zeosil 1165MP"), 25 parts of carbon black (manufactured by Tokai Carbon Co., Ltd., trade name "Seat 9H"), and 2.0 parts of a silane coupling agent: bis(3-(triethoxysilyl)propyl)tetrasulfide (manufactured by Evonik, trade name "Si69") were added, and the mixture was kneaded for 1.5 minutes at a starting temperature of 110°C, after which 3 parts of zinc oxide, 2 parts of stearic acid, and 2 parts of an anti-aging agent: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Nocrac 6C") were added, and the mixture was kneaded for another 2.5 minutes, and the kneaded product was discharged from the mixer. The temperature of the kneaded product at the end of kneading was 150°C. The kneaded product was cooled to room temperature, and then kneaded again in a Banbury mixer at a starting temperature of 110°C for 3 minutes, and then the kneaded product was discharged from the mixer. Next, the obtained kneaded product was kneaded with an open roll at 50°C by adding a mixture of 1.75 parts of sulfur, 1.0 parts of a crosslinking accelerator: N-(tert-butyl)-2-benzothiazole sulfenamide (manufactured by Sanshin Chemical Industry Co., Ltd., product name "Suncerer NS-G"), and 0.53 parts of a crosslinking accelerator: 1,3-diphenylguanidine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Noccelaer D"), and then a sheet-shaped rubber composition was taken out. The obtained rubber composition was press-crosslinked at 160°C for 7 minutes, and a test piece of the crosslinked rubber was prepared and evaluated for fuel economy. The results are shown in Table 3.

[0168] Example 15 After it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, a modified conjugated diene polymer and a cross-linked rubber were obtained and evaluated in the same manner as in Example 14, except that tetramethylethylenediamine was not added. The results are shown in Table 3.

[0169] Comparative Example 3 A modified conjugated diene polymer was obtained in the same manner as in Example 15, except that the polyorganosiloxane represented by the above formula (10) (a xylene solution having a concentration of 40% by weight) was added all at once. Specifically, a polymerization reaction was carried out in the same manner as in Example 15, and after adding 1,6-bis(trichlorosilyl)hexane, a total amount of 0.286 parts (equivalent to 0.600 moles per mole of n-butyllithium used, calculated as epoxy groups in the polyorganosiloxane) of polyorganosiloxane (xylene solution with a concentration of 40% by weight) was added within 1 minute while stirring with a stirrer, and a modification reaction was carried out for 20 minutes while stirring with a stirrer. Then, except for changing the method of adding polyorganosiloxane (40 wt% xylene solution) as described above, a modified conjugated diene polymer and a cross-linked rubber were obtained and evaluated in the same manner as in Example 15. The results are shown in Table 3.

[0170] [Reference example 1] (Production of modified conjugated diene polymer) In an autoclave equipped with a stirrer, 400.0 parts of cyclohexane, 16.0 parts of styrene, 44.0 parts of 1,3-butadiene, and 0.092 parts of tetramethylethylenediamine were charged under a nitrogen atmosphere. In order to detoxify impurities that act on deactivation of polymerization in advance, normal butyl lithium was added to the autoclave as a scavenger, and then 6.5 parts of the solution containing the polymer block (A) having an active terminal obtained in the above Example 1 (the amount of the polymer block (A) used was 1.96 parts) was added, and polymerization was started at 40°C. 10 minutes after the start of polymerization, 5.0 parts of styrene and 35.0 parts of 1,3-butadiene were continuously added over 40 minutes. The maximum temperature during the polymerization reaction was 60°C. After a series of continuous additions, the mixture was stirred for 20 minutes, and after it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, 0.004 parts of 1,6-bis(trichlorosilyl)hexane was added and reacted for 10 minutes. Then, 0.192 parts (corresponding to 1.28 moles per mole of n-butyllithium used) of hydrocarbyl oxirane compound A was added in a xylene solution of 50% by weight concentration within 1 minute under stirring with a stirrer, and the modification reaction was carried out for 25 minutes under stirring with a stirrer. Then, as a polymerization terminator, methanol was added in an amount equivalent to twice the moles of n-butyllithium used to obtain a solution containing a modified conjugated diene polymer. In addition, in Reference Example 1, the concentration of the modified conjugated diene polymer in the solution containing the modified conjugated diene polymer (final polymer concentration) was 20% by weight. Then, 0.20 parts of Irganox 1520L (manufactured by Ciba Specialty Chemicals) was added to this solution as an antiaging agent with respect to 100 parts of the modified conjugated diene polymer, and the solvent was removed by steam stripping, and a solid modified conjugated diene polymer was obtained by hot air drying. The styrene unit amount, vinyl bond amount, peak top molecular weight (Mp), weight average molecular weight (Mw), molecular weight distribution (Mw / Mn), Mooney viscosity, and content ratio of multi-branched bodies of the obtained modified conjugated diene polymer, as well as the maximum power load of the stirrer during the modification reaction with polyorganosiloxane, were measured. The results are shown in Table 4.

[0171] (Production of rubber composition and cross-linked rubber product) A rubber composition and a cross-linked rubber product were prepared in the same manner as in Example 11, except that the modified conjugated diene polymer obtained above was used, and the cross-linked rubber product obtained was used to evaluate fuel economy. The results are shown in Table 4.

[0172] [Reference example 2] A modified conjugated diene polymer was obtained in the same manner as in Reference Example 1, except that the hydrocarbyloxirane compound A was added continuously instead of all at once. Specifically, polymerization reaction was carried out in the same manner as in Reference Example 1, and 1,6-bis(trichlorosilyl)hexane was added, and then hydrocarbyl oxirane compound A was added continuously and at a constant rate in a xylene solution of 50% by weight concentration over 21 minutes from the start of addition under stirring with a stirrer. The total amount of hydrocarbyl oxirane compound B added was 0.192 parts (corresponding to 1.28 moles per mole of n-butyl lithium used). Then, modification reaction was carried out for 25 minutes from the start of addition of hydrocarbyl oxirane compound A under stirring with a stirrer. Then, except for changing the method of adding the hydrocarbyl oxirane compound A as described above, a modified conjugated diene polymer and a cross-linked rubber were obtained and evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

[0173] [Reference example 3] A modified conjugated diene polymer and a cross-linked rubber were obtained and evaluated in the same manner as in Reference Example 2, except that the hydrocarbyl oxirane compound A (40% by weight xylene solution) was added continuously and at a constant speed under stirring with a stirrer for 4 minutes from the start of addition. The results are shown in Table 4.

[0174] [Table 1]

[0175] [Table 2]

[0176] [Table 3]

[0177] [Table 4]

[0178] As shown in Tables 1, 2, and 3, when reacting the polyorganosiloxane represented by the general formula (1) with the conjugated diene polymer chain having an active terminal, the polyorganosiloxane represented by the general formula (1) was added continuously over 2 to 60 minutes or added in several divided portions in Examples 1 to 15, the maximum power load of the stirrer in the modification reaction can be reduced, and thus it is possible to produce a modified conjugated diene polymer with a low power load, and it is excellent in energy efficiency, and furthermore, it is possible to produce a higher polymer concentration while maintaining high energy efficiency. In addition, the modified conjugated diene polymer obtained had good fuel economy. In particular, as is clear from the results of Examples 9 and 10, even when the polymer concentration was increased, the maximum power load of the stirrer could be kept low.

[0179] In addition, from the results of Table 4, when a different silane-based modifier was used instead of the polyorganosiloxane represented by the general formula (1) (Reference Examples 1 to 3), the maximum power load of the agitator did not decrease even if the modifier was added continuously or in portions, but rather increased. Therefore, it can be said that the effect of adding continuously or in portions is a unique effect when the polyorganosiloxane represented by the general formula (1) is used.

Claims

1. A first step of polymerizing a monomer including a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene polymer chain having an active terminal; The method for producing a modified conjugated diene polymer includes a second step of reacting the conjugated diene polymer chain having an active terminal with the polyorganosiloxane by continuously adding the polyorganosiloxane represented by the following general formula (1) to the conjugated diene polymer chain having an active terminal over a period of 2 to 60 minutes or by adding the polyorganosiloxane in multiple portions: 【Chemistry 10】 (In the above general formula (1), R １ ~R ８ are hydrocarbon groups having 1 to 20 carbon atoms, and may be the same or different. X １ and X ４ is a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a polar functional group having an atom of Group 15 or Group 16 of the periodic table, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may have the polar functional group or a halogen atom, and these may be the same or different. X ２ is a group represented by the following general formula (5), ２ When there are a plurality of X, they may be the same or different. ３ is a group containing 2 to 20 repeating alkylene glycol units, X ３ may be a group derived from a group containing 2 to 20 repeating units of alkylene glycol; ３ When there are a plurality of, they may be the same or different. m is an integer of 1 to 200, n is an integer of 0 to 200, and k is an integer of 0 to 200. -Z 3 -Z 4 -E 2 (5) (Z 3 is an alkylene group having 1 to 10 carbon atoms, Z 4 is a methylene group, a sulfur atom or an oxygen atom, and E 2 is a glycidyl group).

2. The X １ and X ４ The method for producing a modified conjugated diene polymer according to claim 1, wherein is a hydrocarbon group having 1 to 20 carbon atoms.

3. 3. The method for producing a modified conjugated diene polymer according to claim 1, wherein the modified conjugated diene polymer contains an isoprene-containing block containing 80 to 100% by weight of isoprene units.

4. 3. The method for producing a modified conjugated diene-based polymer according to claim 1, wherein a total of 0.5 to 5.0 moles of the polar compound is added per mole of the polymerization initiator before the second step.

5. A method for producing a rubber composition, comprising obtaining a modified conjugated diene polymer by the method according to claim 1 or 2, and adding silica to the modified conjugated diene polymer.

6. The method for producing a rubber composition according to claim 5, further comprising adding a crosslinking agent.

7. A method for producing a cross-linked rubber product, comprising obtaining a rubber composition by the method according to claim 6 and cross-linking the rubber composition.

8. A method for producing a tire, comprising obtaining a rubber composition by the production method according to claim 7 and crosslinking the rubber composition to produce a tire comprising a crosslinked rubber product of the rubber composition.

Images