Method for producing polymer composition

Abstract

Provided is a polymer composition manufacturing method that is suited to the manufacture of a crosslinked polymer (tire) having satisfactory workability, satisfactory filler dispersion if a filler is included therein, and excellent low hysteresis loss.　This polymer composition manufacturing method has: a first step for kneading (A) a conjugated diene-based polymer, which is a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound, and is a reaction product of an active polymerization end and a compound represented by any one of general formulas (1)-(3), together with (B) a basic compound having an acid dissociation constant of 8.0 or greater; and a second step for kneading a crosslinking agent and the kneaded product obtained in the first step.

Description

[Technical field]

[0001] The present invention relates to a process for producing a polymer composition. [Background technology]

[0002] In recent years, in connection with the movement towards global carbon dioxide emission regulations accompanying the growing interest in environmental issues, there has been an increasing demand for improved fuel efficiency in automobiles. In order to meet such demands, there is also a demand for reduced rolling resistance in tire performance. Conventionally, methods for optimizing tire structure have been considered as a method for reducing tire rolling resistance, but currently, a common method is to use polymer compositions applied to tires that have low tan δ (hereinafter also referred to as "low hysteresis loss") and excellent low heat generation properties.

[0003] Possible methods for obtaining such a polymer composition with low heat buildup include reducing the amount of filler such as carbon black or silica, or using carbon black with a large particle size. However, any of these methods inevitably results in a decrease in the reinforcement, abrasion resistance, and grip on wet road surfaces (hereinafter also referred to as "wet grip") of the polymer composition.

[0004] Therefore, for example, a study has been conducted on the use of a modified conjugated diene-based polymer obtained by forming an activated polymer having a metal terminal and modifying the activated polymer by introducing a specific modifier as a tire tread material (see, for example, Patent Document 1). Patent Document 1 discloses that the use of this material as a tire tread material results in excellent heat build-up, wear resistance, and wet grip properties. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2016-528369 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the modified conjugated diene-based polymer disclosed in Patent Document 1 is used as a tire tread material, the processability is poor due to a strong interaction with a filler such as silica contained in the polymer composition, and the polymer cannot be sufficiently kneaded, so that the polymer cannot exhibit its performance.

[0007] Therefore, some aspects of the present invention provide a method for producing a polymer composition which has good processability, and in the case where a filler is contained, has good dispersibility of the filler, and is suitable for producing a crosslinked polymer (tire) excellent in low hysteresis loss. [Means for solving the problem]

[0008] The present invention has been made to solve at least some of the above problems, and can be realized in the following aspects.

[0009] One embodiment of the method for producing a polymer composition according to the present invention comprises the steps of: A first step of kneading (A) a conjugated diene polymer which is a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound, and which is a reaction product of an active polymerization terminal and a compound represented by any one of the following general formulas (1) to (3), and (B) a basic compound having an acid dissociation constant of 8.0 or more; A second step of kneading the kneaded product obtained in the first step with a crosslinking agent; has. [ka] (In formula (1), A 2 is an imino group, an amide group, a (thio)carbonyl group, a (thio)carbonyloxy group, a sulfide or a polysulfide. 2or represents a protected primary amino group, a protected secondary amino group, a tertiary amino group, a nitrile group, a pyridyl group, a (thio)epoxy group, a (thio)isocyanate group, a (thio)formyl group, a (thio)carboxylate ester, a metal salt of a (thio)carboxylate ester, a carboxylic acid halide compound, an imidazolyl group, a group represented by the following formula (1a) or a group represented by the following formula (1b), 2 and L 3 each independently represents a single bond or a hydrocarbylene group having 1 to 20 carbon atoms; R 3 and R 4 each independently represents a hydrocarbyl group having 1 to 4 carbon atoms, n2 is 0 to 3, and m1 is 0 or 1. [ka] (In formula (1a), L 3 , R 3 , R 4 and n2 are the same as in formula (1), n5 is 1 or 2, m2 is 0 to 2, R 11 represents an alkanediyl group having 1 to 20 carbon atoms. 3 may be the same or different. * represents L 2 This indicates the site of binding to [ka] (In formula (1b), R 3 and R 4 is the same as in formula (1), and n5 and R 11 is the same as formula (1a). * is L 2 This indicates the site of binding to [ka] (In formula (2), A 3 each independently represents an imino group, an amido group, a (thio)carbonyl group, a (thio)carbonyloxy group, a secondary amino group, or a tertiary amino group; Z represents a t-valent group having 1 to 20 carbon atoms which may or may not contain a nitrogen atom; L 4represents a single bond or a hydrocarbylene group having 1 to 20 carbon atoms; L 5 represents a hydrocarbylene group having 1 to 20 carbon atoms, R 5 and R 6 each independently represents a hydrocarbyl group having 1 to 4 carbon atoms, n3 is 0 or 1, and t is 2 or 3. [ka] (In formula (3), R 7 and R 8 each independently represents a hydrocarbyl group having 1 to 20 carbon atoms; R 9 represents a hydrocarbyl group having 1 to 20 carbon atoms, a substituted alkyl group having 1 to 20 carbon atoms in which at least one of the hydrogen atoms and -CH2- groups in the alkyl group is substituted with a group containing at least one element selected from the group consisting of silicon, nitrogen, phosphorus, oxygen and sulfur, or an aromatic group having 6 to 20 carbon atoms containing at least one element selected from the group consisting of nitrogen, phosphorus, oxygen and sulfur; R 10 represents an alkanediyl group having 1 to 20 carbon atoms. n4 is 1 or 2.

[0010] In one embodiment of the method for producing the polymer composition, The basic compound having an acid dissociation constant of 8.0 or more may be an amine compound.

[0011] In any one of the embodiments of the method for producing a polymer composition, The basic compound having an acid dissociation constant of 8.0 or more may be a guanidine compound.

[0012] In any one of the embodiments of the method for producing a polymer composition, In the second step, an acidic compound can be kneaded together with the kneaded mixture and the crosslinking agent.

[0013] In any one of the embodiments of the method for producing a polymer composition, The acidic compound may be a saturated fatty acid having 12 to 24 carbon atoms.

[0014] In any one of the embodiments of the method for producing a polymer composition, In the first step, silica can be kneaded together with the conjugated diene polymer and the basic compound having an acid dissociation constant of 8.0 or more.

[0015] In any one of the embodiments of the method for producing a polymer composition, In the first step, the conjugated diene polymer, the basic compound having an acid dissociation constant of 8.0 or more, and the silica are kneaded together, and then a silane coupling agent is added and further kneaded.

[0016] In any one of the embodiments of the method for producing a polymer composition, The crosslinking agent can be sulfur. Effect of the Invention

[0017] According to the method for producing a polymer composition of the present invention, it is possible to produce a polymer composition which has good processability, and in the case where a filler is contained, has good dispersibility of the filler, and is suitable for producing a crosslinked polymer (tire) excellent in low hysteresis loss. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Preferred embodiments of the present invention will be described in detail below. Note that the present invention is not limited to the embodiments described below, and should be understood to include various modified examples that are implemented within the scope of the present invention.

[0019] In this specification, a numerical range described as "X to Y" means that the range includes the numerical value X as the lower limit and the numerical value Y as the upper limit.

[0020] In this specification, the term "(meth)acrylic acid" is a concept including both acrylic acid and methacrylic acid.

[0021] 1. Method for producing polymer composition A method for producing a polymer composition according to one embodiment of the present invention includes a first step of kneading (A) a conjugated diene polymer (hereinafter also referred to as "(A) conjugated diene polymer"), which is a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound and is a reaction product of an active polymerization terminal and a compound represented by any one of the following general formulas (1) to (3), and (B) a basic compound having an acid dissociation constant of 8.0 or more (hereinafter also referred to as "(B) basic compound"), and a second step of kneading the kneaded product obtained in the first step with a crosslinking agent.

[0022] The polymer composition obtained by the production method according to the present embodiment is an unvulcanized polymer composition obtained by kneading (A) a conjugated diene polymer, (B) a basic compound, and, if necessary, other additives. This polymer composition is subjected to a crosslinking treatment such as vulcanization to form a crosslinked polymer.

[0023] Hereinafter, the method for producing the polymer composition according to this embodiment will be described.

[0024] 1.1. First step The first step is a step of kneading (A) a conjugated diene polymer and (B) a basic compound to obtain a kneaded product containing the conjugated diene polymer and the basic compound. In this first step, all or a part of the basic compound (B) may be produced by kneading a compound for producing the basic compound (B) (hereinafter also referred to as a "producing compound") with the conjugated diene polymer (A). That is, all or a part of the basic compound (B) may be produced during the first step.

[0025] In the first step, the conjugated diene polymer (A), the basic compound (B), and silica may be kneaded together, and then the silane coupling agent may be added and further kneaded. When the basic compound (B) is produced in the first step, the silica and the silane coupling agent may be kneaded together with the conjugated diene polymer (A) and the compound for producing the basic compound.

[0026] In the first step, if necessary, other polymers (polymers other than the conjugated diene polymer (A)), extenders, antioxidants, etc. may also be kneaded together. Furthermore, in the first step, an acidic compound, which is preferably kneaded in the second step, may also be kneaded together.

[0027] In this way, in the first step, other components can be kneaded together with the conjugated diene polymer (A) and the basic compound or forming compound (B), but the kneading of the basic compound and / or forming compound and the conjugated diene polymer (A) is started at the same time. The other components may be started to be kneaded at the same time as the conjugated diene polymer (A), or may be added and kneaded after the conjugated diene polymer (A) and the basic compound and / or forming compound (B) are kneaded. When the basic compound and / or forming compound (B) is added and kneaded after the other components in the first step, the effect of the present invention may not be sufficiently obtained.

[0028] In producing a polymer composition containing silica, by subjecting the silica to the first step, the dispersibility of the silica can be improved from the viewpoint of a balance with low hysteresis loss in a crosslinked polymer formed from the resulting polymer composition.

[0029] In addition, when a silane coupling agent is used in the first step, it is preferable to first knead (A) the conjugated diene polymer, (B) the basic compound and silica, and then add the silane coupling agent and further knead.

[0030] Specifically, it is preferable to first knead (A) the conjugated diene polymer, (B) the basic compound, and, if necessary, the components other than the silane coupling agent (specifically, silica, etc.) among the components to be subjected to the first step, and then add (post-add) the silane coupling agent to the kneaded mixture and further knead it.

[0031] By adding the silane coupling agent in the first step, the resulting polymer composition has better processability, and the crosslinked polymer formed from the polymer composition has better low hysteresis loss, and the dispersibility of silica can be improved.

[0032] In the case of post-adding the silane coupling agent, the timing of adding the silane coupling agent is appropriately determined depending on the type of silica, the proportion of silica used, the kneading conditions, etc., taking into consideration the type and proportion of the conjugated diene polymer (A), the proportion of the basic compound and / or the generating compound (B), etc.

[0033] In addition, in the case of post-adding the silane coupling agent, it is preferable to blend at least (A) the conjugated diene polymer, (B) the basic compound and / or the generating compound, and silica, and knead them for 0.5 to 10 minutes, and then add and blend the silane coupling agent, and knead them for 0.5 to 10 minutes.

[0034] The kneading machine used in the first step may be an open or closed kneading machine such as a plastomill, a Banbury mixer, a roll, or an internal mixer.

[0035] In the first step, the kneading temperature is 30° C. to 180° C., and preferably 50° C. to 160° C. If the kneading temperature in the first step is 160° C. or higher, the processability of the resulting polymer composition may be deteriorated.

[0036] In addition, when a silane coupling agent is used in the first step, the method is not limited to adding the silane coupling agent later and kneading it, and the silane coupling agent may be kneaded together with all other components to be used in the first step at the same time to obtain a kneaded product containing the silane coupling agent.

[0037] Each component used in the first step will be described in detail below.

[0038] 1.1.1.(A) Conjugated diene polymer The conjugated diene polymer (A) is a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound, and is a reaction product between an active polymerization terminal and a compound represented by any one of the following general formulas (1) to (3).

[0039] [ka] (In formula (1), A 2 is an imino group, an amide group, a (thio)carbonyl group, a (thio)carbonyloxy group, a sulfide or a polysulfide. 2 or represents a protected primary amino group, a protected secondary amino group, a tertiary amino group, a nitrile group, a pyridyl group, a (thio)epoxy group, a (thio)isocyanate group, a (thio)formyl group, a (thio)carboxylate ester, a metal salt of a (thio)carboxylate ester, a carboxylic acid halide compound, an imidazolyl group, a group represented by the following formula (1a) or a group represented by the following formula (1b), 2 and L 3 each independently represents a single bond or a hydrocarbylene group having 1 to 20 carbon atoms; R 3 and R 4 each independently represents a hydrocarbyl group having 1 to 4 carbon atoms, n2 is 0 to 3, and m1 is 0 or 1.

[0040] [ka] (In formula (1a), L 3 , R 3 , R 4 and n2 are the same as in formula (1), n5 is 1 or 2, m2 is 0 to 2, R 11 represents an alkanediyl group having 1 to 20 carbon atoms. 3 may be the same or different. * represents L 2 This indicates the site of binding to

[0041] [ka] (In formula (1b), R 3 and R 4 is the same as in formula (1), and n5 and R 11 is the same as formula (1a). * is L 2 The binding site is shown.

[0042] [ka] (In formula (2), A 3 each independently represents an imino group, an amido group, a (thio)carbonyl group, a (thio)carbonyloxy group, a secondary amino group, or a tertiary amino group; Z represents a t-valent group having 1 to 20 carbon atoms which may or may not contain a nitrogen atom; L 4 represents a single bond or a hydrocarbylene group having 1 to 20 carbon atoms; L 5 represents a hydrocarbylene group having 1 to 20 carbon atoms, R 5 and R 6 each independently represents a hydrocarbyl group having 1 to 4 carbon atoms, n3 is 0 or 1, and t is 2 or 3.

[0043] [ka] (In formula (3), R 7 and R 8 each independently represents a hydrocarbyl group having 1 to 20 carbon atoms; R 9represents a hydrocarbyl group having 1 to 20 carbon atoms, a substituted alkyl group having 1 to 20 carbon atoms in which at least one of the hydrogen atoms and -CH2- groups in the alkyl group is substituted with a group containing at least one element selected from the group consisting of silicon, nitrogen, phosphorus, oxygen and sulfur, or an aromatic group having 6 to 20 carbon atoms containing at least one element selected from the group consisting of nitrogen, phosphorus, oxygen and sulfur; R 10 represents an alkanediyl group having 1 to 20 carbon atoms. n4 is 1 or 2.

[0044] The (A) conjugated diene polymer has a structural unit derived from a conjugated diene compound and has a structure derived from any of the compounds of the above general formulas (1) to (3) at an active polymerization end. Such a (A) conjugated diene polymer can be obtained by first polymerizing a monomer containing a conjugated diene compound in the presence of an alkali metal compound or an alkaline earth metal compound to obtain a polymer having an active polymerization end (polymerization step), and then reacting the polymer having an active polymerization end with any of the compounds of the above general formulas (1) to (3) (hereinafter also referred to as a "specific modifier") (modification step).

[0045] <Polymerization process> Examples of conjugated diene compounds that can be used in polymerization include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 1,3-heptadiene, 2-phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, and 2-chloro-1,3-butadiene. Among these, 1,3-butadiene, isoprene, and 2,3-dimethyl-1,3-butadiene are preferred. Conjugated diene compounds can be used alone or in combination of two or more.

[0046] The (A) conjugated diene polymer may be a homopolymer of a conjugated diene compound, but is preferably a copolymer of a conjugated diene compound and an aromatic vinyl compound from the viewpoint of increasing the strength of the crosslinked polymer. In particular, it is preferably a copolymer containing 1,3-butadiene and styrene in the monomer composition, in terms of high living property in anionic polymerization. When the (A) conjugated diene polymer is a copolymer of a conjugated diene compound and an aromatic vinyl compound, the (A) conjugated diene polymer typically has a random copolymerization portion in which the distribution of the conjugated diene compound and the aromatic vinyl compound is irregular, and may further have a block portion consisting of a structural unit derived from the conjugated diene compound or the aromatic vinyl compound.

[0047] Examples of aromatic vinyl compounds that can be used in the polymerization include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 5-tert-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethylether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-tert-butylstyrene, 3-tert-butylstyrene, 4-tert-butylstyrene, vinylxylene, vinylnaphthalene, vinylpyridine, diphenylethylene, and tertiary amino group-containing diphenylethylene (e.g., 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene). Among these, styrene and α-methylstyrene are preferred. The aromatic vinyl compounds can be used alone or in combination of two or more.

[0048] When the (A) conjugated diene polymer is a copolymer of a conjugated diene compound and an aromatic vinyl compound, the content of the aromatic vinyl compound (aromatic vinyl content) is preferably 3 to 55 mass%, more preferably 5 to 50 mass%, based on 100 mass% of the total of the conjugated diene compound and the aromatic vinyl compound used in the polymerization, from the viewpoint of achieving a good balance between low hysteresis loss and wet grip properties of the resulting crosslinked polymer. 1 It can be measured by H-NMR.

[0049] In the polymerization, other monomers may be used in addition to the conjugated diene compound and the aromatic vinyl compound. Examples of the other monomers include acrylonitrile, methyl (meth)acrylate, ethyl (meth)acrylate, and hydroxyethyl (meth)acrylate. The amount of the other monomers used is preferably 25% by mass or less, more preferably 15% by mass or less, and particularly preferably 10% by mass or less, based on 100% by mass of the total amount of the monomers used in the polymerization.

[0050] The polymerization method used may be any of solution polymerization, gas phase polymerization, and bulk polymerization, but solution polymerization is particularly preferred. The polymerization form may be any of batch and continuous. When using solution polymerization, a specific example of the polymerization method is a method in which a monomer containing a conjugated diene compound is polymerized in an organic solvent in the presence of a polymerization initiator and a randomizer used as necessary.

[0051] As the polymerization initiator, an alkali metal compound or an alkaline earth metal compound can be used. Specific examples of these include alkyl lithium such as methyl lithium, ethyl lithium, n-propyl lithium, n-butyl lithium, sec-butyl lithium, and tert-butyl lithium, 1,4-dilithiobutane, phenyl lithium, stilbene lithium, naphthyl lithium, 1,3-bis(1-lithio-1,3-dimethylpentyl)benzene, 1,3-phenylenebis(3-methyl-1-phenylpentylidene)dilithium, 3-(dimethylamino)propyl lithium, naphthyl sodium, naphthyl potassium, di-n-butyl magnesium, di-n-hexyl magnesium, ethoxy potassium, and calcium stearate. Among these, lithium compounds are preferred. The total amount of the polymerization initiator to be used is preferably 0.2 to 20 mmol per 100 g of monomer to be used in polymerization. The polymerization initiator can be used alone or in combination of two or more.

[0052] The polymerization reaction may be carried out in the presence of a compound (hereinafter also referred to as a "modified initiator") obtained by mixing an alkali metal compound or an alkaline earth metal compound with a compound having a functional group that interacts with silica. By carrying out the polymerization in the presence of a modified initiator, a functional group that interacts with silica can be introduced into the polymerization initiation terminal of the conjugated diene polymer (A). In this specification, "interaction" means forming a covalent bond between molecules or forming an intermolecular force weaker than a covalent bond (for example, an electromagnetic force acting between molecules such as an ion-dipole interaction, a dipole-dipole interaction, a hydrogen bond, or a van der Waals force). The "functional group that interacts with silica" preferably has at least one selected from the group consisting of a nitrogen atom, a sulfur atom, a phosphorus atom, and an oxygen atom.

[0053] The modified initiator is preferably a reaction product of a lithium compound such as an alkyl lithium and a nitrogen-containing compound such as a secondary amine compound. Specific examples of the nitrogen-containing compound include dimethylamine, diethylamine, dipropylamine, dibutylamine, dodecamethyleneimine, N,N'-dimethyl-N'-trimethylsilyl-1,6-diaminohexane, piperidine, pyrrolidine, hexamethyleneimine, heptamethyleneimine, dicyclohexylamine, N-methylbenzylamine, di-(2-ethylhexyl)amine, diallylamine, morpholine, N-(trimethylsilyl)piperazine, N-(tert-butyldimethylsilyl)piperazine, 1,3-ditrimethylsilyl-1,3,5-triazinane, etc. In addition, when polymerization is performed in the presence of a modified initiator, an alkali metal compound or an alkaline earth metal compound may be mixed in advance with a compound having a functional group that interacts with silica to prepare a modified initiator, and the prepared modified initiator may be added to the polymerization system to perform polymerization. Alternatively, an alkali metal compound or an alkaline earth metal compound and a compound having a functional group that interacts with silica may be added to the polymerization system, and the two may be mixed in the polymerization system to prepare a modified initiator and perform polymerization. Alternatively, a nitrogen-containing alkyl lithium compound may be used. A specific example of a nitrogen-containing alkyl lithium compound is a reaction product of 3-dimethylaminopropyl lithium and isoprene.

[0054] The randomizer can be used for the purpose of adjusting the vinyl bond content, which indicates the content of vinyl bonds (1,2-bonds and 3,4-bonds) in the polymer. Examples of the randomizer include dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, 2,2-di(tetrahydrofuryl)propane, 2-(2-ethoxyethoxy)-2-methylpropane, triethylamine, pyridine, N-methylmorpholine, and tetramethylethylenediamine. These can be used alone or in combination of two or more.

[0055] The organic solvent used in the polymerization may be any organic solvent inert to the reaction, and may be, for example, an aliphatic hydrocarbon, an alicyclic hydrocarbon, or an aromatic hydrocarbon. Among them, a hydrocarbon having 3 to 8 carbon atoms is preferred, and specific examples thereof include, for example, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2-butene, cis-2-butene, 1-pentyne, 2-pentyne, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene, heptane, cyclopentane, methylcyclopentane, methylcyclohexane, 1-pentene, 2-pentene, and cyclohexene. The organic solvent may be used alone or in combination of two or more.

[0056] When solution polymerization is used, the monomer concentration in the reaction solvent is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, from the viewpoint of maintaining a balance between productivity and ease of polymerization control. The temperature of the polymerization reaction is preferably -20°C to 150°C, more preferably 0°C to 120°C, and particularly preferably 20°C to 100°C. The polymerization reaction is preferably carried out under a pressure sufficient to keep the monomers substantially in a liquid phase. Such a pressure can be obtained by a method such as pressurizing the inside of a reactor with a gas inert to the polymerization reaction. A conjugated diene-based polymer having an active polymerization terminal can be obtained by such a polymerization reaction.

[0057] In the conjugated diene polymer having an active polymerization end, the vinyl bond content in the structural units derived from the conjugated diene compound is preferably 30 to 65 mol%, more preferably 33 to 62 mol%, and particularly preferably 35 to 60 mol%. If the vinyl bond content is less than 30 mol%, the grip properties tend to be too low, and if it exceeds 65 mol%, the abrasion resistance of the resulting crosslinked polymer tends to be easily deteriorated. In this specification, the "vinyl bond content" is a value indicating the content ratio of structural units having vinyl bonds to all structural units derived from the conjugated diene compound in the conjugated diene polymer, 1 The values ​​were measured by H-NMR.

[0058] <Denaturation process> Next, the active polymerization terminals of the conjugated diene polymer obtained by the polymerization reaction are reacted with compounds (specific modifiers) represented by the following general formulas (1) to (3). Through these steps, a conjugated diene polymer (A) that has been terminally modified with a specific modifier can be obtained. The conjugated diene polymer (A) that has been terminally modified with such a specific modifier has improved wet grip properties and low hysteresis loss due to a stronger interaction with the filler at the terminal modified sites, and the branching properties of the imine also improve processability and filler dispersibility.

[0059] [ka] (In formula (1), A 2 is an imino group, an amide group, a (thio)carbonyl group, a (thio)carbonyloxy group, a sulfide or a polysulfide. 2 or represents a protected primary amino group, a protected secondary amino group, a tertiary amino group, a nitrile group, a pyridyl group, a (thio)epoxy group, a (thio)isocyanate group, a (thio)formyl group, a (thio)carboxylate ester, a metal salt of a (thio)carboxylate ester, a carboxylic acid halide compound, an imidazolyl group, a group represented by the following formula (1a) or a group represented by the following formula (1b),2 and L 3 each independently represents a single bond or a hydrocarbylene group having 1 to 20 carbon atoms; R 3 and R 4 each independently represents a hydrocarbyl group having 1 to 4 carbon atoms, n2 is 0 to 3, and m1 is 0 or 1.

[0060] [ka] (In formula (1a), L 3 , R 3 , R 4 and n2 are the same as in formula (1), n5 is 1 or 2, m2 is 0 to 2, R 11 represents an alkanediyl group having 1 to 20 carbon atoms. 3 may be the same or different. * represents L 2 This indicates the site of binding to

[0061] [ka] (In formula (1b), R 3 and R 4 is the same as in formula (1), and n5 and R 11 is the same as formula (1a). * is L 2 This indicates the site of binding to

[0062] In the above formula (1), L 2 and L 3 Examples of the hydrocarbylene group having 1 to 20 carbon atoms include a linear or branched alkanediyl group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, and an arylene group having 6 to 20 carbon atoms. 3 and R 4 Examples of the hydrocarbyl group having 1 to 4 carbon atoms include a linear or branched alkyl group having 1 to 4 carbon atoms and a cycloalkyl group having 3 to 4 carbon atoms.

[0063] Specific examples of the compound represented by the above general formula (1) include N-(3-imidazolylpropyl)-N,N-bis(3-trimethoxysilylpropyl)amine, N-(3-imidazolylpropyl)-N,N-bis(3-triethoxysilylpropyl)amine, N,N-bis(trimethoxysilyl)aminopropylmethyldiethylsilane, N,N,N-tris(triethoxysilylpropyl)amine, N,N,N',N'-tetrakis(3-triethoxysilylpropyl)-1,3-diaminopropane, N-(3-(2,2 -diethoxy-1,2-azasilolidine-1-yl)propyl)-N,N',N'-tris(3-(triethoxysilyl)propyl)propane-1,3-diamine, N,N-bis(3-(2,2-diethoxy-1,2-azasilolidine-1-yl)propyl)-N',N'-bis(3-(triethoxysilyl)propyl)propane-1,3-diamine, 3-(2,2-diethoxy-1,2-azasilolidine-1-yl)-N,N-bis(3-(triethoxysilyl)propyl)propan-1-amine, and the like.

[0064] [ka] (In formula (2), A 3 each independently represents an imino group, an amido group, a (thio)carbonyl group, a (thio)carbonyloxy group, a secondary amino group, or a tertiary amino group; Z represents a t-valent group having 1 to 20 carbon atoms which may or may not contain a nitrogen atom; L 4 represents a single bond or a hydrocarbylene group having 1 to 20 carbon atoms; L 5 represents a hydrocarbylene group having 1 to 20 carbon atoms, R 5 and R 6 each independently represents a hydrocarbyl group having 1 to 4 carbon atoms, n3 is 0 or 1, and t is 2 or 3.

[0065] In the above formula (2), Z is a divalent or trivalent group having 1 to 20 carbon atoms which may contain a nitrogen atom, and preferably contains a nitrogen atom. 4 A hydrocarbylene group having 1 to 20 carbon atoms and L5 Examples of the hydrocarbylene group having 1 to 20 carbon atoms include a linear or branched alkanediyl group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, and an arylene group having 6 to 20 carbon atoms. 5 and R 6 Examples of the hydrocarbyl group having 1 to 4 carbon atoms include a linear or branched alkyl group having 1 to 4 carbon atoms and a cycloalkyl group having 3 to 4 carbon atoms.

[0066] Specific examples of the compound represented by the above general formula (2) include compounds represented by the following formulae (M-1) to (M-4).

[0067] [ka] In the above formula (M-1), R 12 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and n6 represents an integer of 1 to 10.

[0068] [ka] (In formula (3), R 7 and R 8 each independently represents a hydrocarbyl group having 1 to 20 carbon atoms; R 9 represents a hydrocarbyl group having 1 to 20 carbon atoms, a substituted alkyl group having 1 to 20 carbon atoms in which at least one of the hydrogen atoms and -CH2- groups in the alkyl group is substituted with a group containing at least one element selected from the group consisting of silicon, nitrogen, phosphorus, oxygen and sulfur, or an aromatic group having 6 to 20 carbon atoms containing at least one element selected from the group consisting of nitrogen, phosphorus, oxygen and sulfur; R 10 represents an alkanediyl group having 1 to 20 carbon atoms. n4 is 1 or 2.

[0069] In the above formula (3), R 7 and R 8Examples of the hydrocarbyl group having 1 to 20 carbon atoms include a linear or branched alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms.

[0070] Specific examples of the compound represented by the above general formula (3) include N-phenyl-2,2-dimethoxy-1-aza-2-silacyclopentane, N-(3-trimethoxysilylpropyl)-2,2-dimethoxy-1-aza-2-silacyclopentane, and N-(3-triethoxysilylpropyl)-2,2-dimethoxy-1-aza-2-silacyclopentane.

[0071] In the modification reaction of the conjugated diene polymer having an active polymerization terminal, the specific modifier may be used alone, or a modifier other than the specific modifier (hereinafter also referred to as "other modifier") may be used together with the specific modifier. The other modifier is not particularly limited as long as it has a functional group that interacts with the filler and can react with the active polymerization terminal of the polymer.

[0072] The above modification reaction can be carried out, for example, as a solution reaction. This solution reaction may be carried out using a solution containing unreacted monomers after the polymerization reaction is completed, or the conjugated diene polymer contained in the solution may be isolated and dissolved in a suitable solvent such as cyclohexane before the reaction. The modification reaction may be carried out either batchwise or continuously. In this case, the method of adding the modifier is not particularly limited, and examples of the method include a method of adding the modifier all at once, a method of adding the modifier in portions, and a method of adding the modifier continuously.

[0073] The proportion of the specific modifier used (the total amount when two or more types are used) is preferably 0.2 mol or more, more preferably 0.4 mol or more, per mol of the metal atom involved in the polymerization reaction of the polymerization initiator. By making it 0.2 mol or more, the modification reaction of the polymer terminal by the specific modifier can be sufficiently advanced, and the interaction with the filler at the modified terminal site can be sufficiently strengthened. In addition, in order to reduce unreacted matter in the solution after the modification reaction, the upper limit of the proportion of the specific modifier used is preferably less than 1.5 mol, more preferably less than 1.2 mol, per mol of the metal atom involved in the polymerization reaction of the polymerization initiator.

[0074] In addition, when the specific modifier and other modifiers are used in combination in the modification reaction, the proportion of the other modifier used is preferably 30 mol % or less, more preferably 20 mol % or less, and particularly preferably 10 mol % or less, based on the total proportion of the specific modifier and other modifiers used, from the viewpoint of sufficiently proceeding the reaction between the conjugated diene polymer and the specific modifier.

[0075] The temperature of the modification reaction is usually the same as the temperature of the polymerization reaction, and is preferably -20°C to 150°C, more preferably 0°C to 120°C, and particularly preferably 20°C to 100°C. If the temperature of the modification reaction is low, the viscosity of the modified conjugated diene polymer tends to increase. On the other hand, if the temperature of the modification reaction is high, the active terminal of the polymer is easily deactivated. The reaction time of the modification reaction is preferably 1 minute to 5 hours, and more preferably 2 minutes to 1 hour.

[0076] The conjugated diene polymer (A) contained in the reaction solution can be isolated by a known solvent removal method such as steam stripping and drying such as heat treatment. The obtained conjugated diene polymer (A) may be adjusted in Mooney viscosity by adding an extender oil or the like as necessary. This treatment can improve processability. Examples of the extender oil include aromatic oil, naphthenic oil, and paraffin oil. The amount of the extender oil to be added may be appropriately determined depending on the monomers used in polymerization, and is, for example, 10 to 50 parts by mass relative to 100 parts by mass of the conjugated diene polymer.

[0077] In this way, the conjugated diene polymer (A) can be obtained. The conjugated diene polymer (A) can improve compatibility with fillers, and can provide a polymer composition with improved processability and filler dispersibility. By using a polymer composition containing such a conjugated diene polymer (A), a tire (crosslinked polymer) with low hysteresis loss and excellent wet grip properties required for applications such as automobile tires can be obtained.

[0078] The (A) conjugated diene polymer preferably has a structure derived from any of the compounds of the above general formulas (1) to (3) at least at one end of the polymer. When the (A) conjugated diene polymer has such a structure, the dispersibility of fillers such as carbon black and silica is further improved when the polymer is applied to, for example, tires, and this is preferable in that it provides a higher improvement in low hysteresis loss and wet grip properties.

[0079] The weight average molecular weight (Mw) of the conjugated diene polymer (A) measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 100,000 to 2,000,000. If the Mw is less than 100,000, the low hysteresis loss and abrasion resistance of the crosslinked polymer of the obtained polymer composition tend to be easily reduced, and if it is more than 2,000,000, the processability of the polymer composition tends to be easily reduced. The weight average molecular weight (Mw) of the obtained conjugated diene polymer (A) is more preferably 150,000 to 1,500,000, and further preferably 200,000 to 1,000,000.

[0080] The molecular weight distribution of the (A) conjugated diene polymer, i.e., the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 1.5 to 3.0, more preferably 1.5 to 2.5, and particularly preferably 1.5 to 2.2. When the (A) conjugated diene polymer has a molecular weight distribution within the above range, it is easy to obtain better low hysteresis loss, abrasion resistance, wet grip performance, and mechanical properties.

[0081] 1.1.2.(B) Basic compounds The (B) basic compound is a compound having an acid dissociation constant (pKa) of 8.0 or more. By kneading the (A) conjugated diene polymer and the (B) basic compound together, the kneading time can be shortened. This is considered to be because the presence of the (B) basic compound promotes the dissociation of the association state between the functional groups of the (A) conjugated diene polymer. In addition, in the second step described below, the bonding between the (A) conjugated diene polymer and the crosslinking agent is likely to be promoted.

[0082] As the (B) basic compound, an amine compound is preferably used. Specific examples of such amine compounds include pyrrole (pKa=23.0), indole (pKa=21.0), carbazole (pKa=19.9), pyrazole (pKa=19.8), imidazole (pKa=14.4), guanidine (pKa=13.7), 1,1,3,3-tetramethylguanidine (pKa=13.6), piperidine (pKa=11.2), quinuclidine (pKa=11.0), cyclohexylamine (pKa=10.6), 1,3-diphenylguanidine (pKa=10.1), piperazine (pKa=9.8), 1,2,3-triazole (pKa=9.3), purine (pKa=8.9), triethylenediamine (pKa=8.8), morpholine (pKa=8.4), and derivatives thereof. Among these amine compounds, (A) is preferred because it is easy to promote the bonding between the conjugated diene polymer and the crosslinking agent. vinegar From the viewpoint of low cost, guanidine compounds such as guanidine, 1,3-diphenylguanidine, and 1,1,3,3-tetramethylguanidine are preferably used.

[0083] As the basic compound (B), an aliphatic amine compound having a long chain alkyl group or a long chain alkenyl group is also preferably used. Examples of the aliphatic amine compound having a long chain alkyl group or a long chain alkenyl group include R 1 -NH2, R 1 -N(CH3)2 or R 1 -NH(CH2) x The chemical structure represented by NH2 (R 1x is an alkyl group having 10 to 24 carbon atoms or an alkenyl group having 10 to 24 carbon atoms, and x is an integer of 1 to 5), and acetates thereof. Specific examples include 1-aminoundecane, stearylamine, dimethylstearylamine, laurylamine, dimethyllaurylamine, oleylamine, dimethyloctylamine, beef tallow propylenediamine, stearylamine acetate, and acetates thereof. These aliphatic amine compounds having a long-chain alkyl group or a long-chain alkenyl group can be used alone or in combination of two or more. Among these, stearylamine (pKa=10.6) is preferred from the viewpoints of availability of raw materials and ease of handling.

[0084] The (B) basic compound may be one produced by kneading a plurality of compounds, specifically a plurality of compounds for producing the basic compound (generating compounds), with the (A) conjugated diene polymer in the first step. Here, the (B) basic compound provided in the first step may be all or partly produced from a plurality of generating compounds.

[0085] As the multiple generating compounds, a combination of a sulfenamide compound and a thiazole compound is preferably used. A sulfenamide compound and a thiazole compound are added as the multiple generating compounds to a composition containing (A) a conjugated diene polymer, and kneaded under predetermined conditions to generate a disulfide compound and an amine compound. The generated amine compound is then kneaded as a basic compound with (A) the conjugated diene polymer.

[0086] Examples of sulfenamide compounds constituting the generating compound include N-cyclohexyl-2-benzothiazole sulfenamide (CBS), N-(tert-butyl)-2-benzothiazole sulfenamide (TBBS), N-morpholino-2-benzothiazole sulfenamide (MBS), etc. These compounds can be used alone or in combination of two or more.

[0087] In addition, examples of the thiazole-based compounds constituting the generating compounds include 2-mercaptobenzothiazole (MBT).

[0088] As a combination of a sulfenamide compound and a thiazole compound, a combination of N-cyclohexyl-2-benzothiazolesulfenamide (CBS) and 2-mercaptobenzothiazolyl (MBT), which produces cyclohexylamine (pKa = 10.6), is preferred in terms of availability and the stability of the basic compound produced.

[0089] The proportion of the (B) basic compound used is preferably 0.5 to 10 parts by mass, more preferably 0.8 to 8 parts by mass, and particularly preferably 1 to 5 parts by mass, based on 100 parts by mass of the polymer component. When the proportion of the (B) basic compound used is within the above range, sufficient mechanical strength and abrasion resistance can be imparted to the crosslinked polymer formed from the resulting polymer composition.

[0090] 1.1.3.Other Ingredients In the first step, in addition to the essential components (A) the conjugated diene polymer and (B) the basic compound, optional components may be further added and kneaded as necessary.

[0091] In the polymer component, as an optional component other than the essential component (A) conjugated diene polymer, for example, natural rubber, butadiene rubber, butyl rubber, synthetic isoprene rubber, styrene-butadiene copolymer rubber, ethylene-α-olefin copolymer rubber, ethylene-α-olefin-diene copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber, halogenated butyl rubber, and mixtures thereof may be contained. Among these, it is preferable to contain natural rubber or butadiene rubber because the obtained crosslinked polymer (tire) can achieve a high balance between low hysteresis loss and wet grip performance while maintaining abrasion resistance. The proportion of other polymer components used is preferably 10 to 45 mass% in 100 mass% of the polymer component.

[0092] Examples of optional components other than the polymer component include fillers such as silica and carbon black, silane coupling agents, extender oils, and antioxidants.

[0093] <Silica> Examples of silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, etc. Among these, wet silica is preferred.

[0094] The proportion of silica used is preferably 10 to 200 parts by mass, more preferably 20 to 130 parts by mass, and particularly preferably 25 to 110 parts by mass, relative to 100 parts by mass of the polymer component. When the silica content is within the above range, the resulting crosslinked polymer (tire) can have a highly well-balanced low hysteresis loss and wet grip properties.

[0095] <Silane coupling agent> Examples of the silane coupling agent include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, Examples of the compounds include bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, dimethoxymethylsilylpropyl-benzothiazolyl tetrasulfide, 3-octanoylthio-1-propyltriethoxysilane, etc. These compounds can be used alone or in combination of two or more. Among these, bis(3-triethoxysilylpropyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, and 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide are preferred from the viewpoint of improving reinforcing properties.

[0096] The proportion of the silane coupling agent used is preferably 0.5 to 20 parts by mass relative to 100 parts by mass of silica. When the proportion of the silane coupling agent used is within the above range, sufficient reinforcement and fracture resistance can be imparted to the crosslinked polymer formed from the polymer composition, and the abrasion resistance of the crosslinked polymer can be improved in some cases.

[0097] <Carbon black> Carbon black generally used as a filler can be used. Specific examples of carbon black include GPF, FEF, HAF, ISAF, and SAF. Among these, ISAF, SAF, and HAF are preferred, and ISAF is more preferred.

[0098] The proportion of carbon black used is preferably 0.5 to 100 parts by mass, and more preferably 1 to 50 parts by mass, based on 100 parts by mass of the polymer component.

[0099] <Extension oil> Examples of the extender oil include aromatic oil, naphthenic oil, paraffin oil, etc. The ratio of the extender oil used is preferably 0 to 50 parts by mass with respect to 100 parts by mass of the polymer component.

[0100] <Anti-aging agent> Examples of the antioxidant include N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, etc. The proportion of the antioxidant used is preferably 0.5 to 5 parts by mass based on 100 parts by mass of the polymer component.

[0101] 1.2. The second step The second step is a step of adding at least a crosslinking agent to the kneaded mixture obtained in the first step, and kneading the kneaded mixture with the crosslinking agent to obtain a kneaded mixture containing (A) a conjugated diene-based polymer and (B) a basic compound and a crosslinking agent, i.e., a polymer composition.

[0102] In the second step, it is preferable that an acidic compound is kneaded together with the kneaded mixture obtained in the first step and the crosslinking agent.

[0103] In the second step, a vulcanization aid or a vulcanization accelerator (when the (B) basic compound or the forming compound has a vulcanization accelerating effect, a vulcanization accelerator related to a compound other than the (B) basic compound and the forming compound) is also kneaded together as necessary. Here, when a compound having a vulcanization accelerating effect is used as the forming compound in the first step, it is preferable not to use a vulcanization accelerator in the second step.

[0104] In the second step, a polymer composition is usually obtained by a method in which all components to be subjected to the second step (specifically, the kneaded product obtained in the first step, the crosslinking agent, and other components such as an acidic compound and a vulcanization aid or vulcanization accelerator, which are provided as necessary) are kneaded together.

[0105] By providing an acidic compound in the second step, the resulting polymer composition has better processability, and the crosslinked polymer formed from the polymer composition has better low hysteresis loss. Furthermore, when the polymer composition contains a filler (specifically, silica and carbon black), the dispersibility of the filler can be improved.

[0106] In the second step, the kneading machine used in the first step can be used. In addition, in the second step, the kneading temperature is 30° C. to 130° C., and preferably 50° C. to 110° C. If the kneading temperature in the second step is 130° C. or higher, the processability of the obtained polymer composition may be deteriorated.

[0107] Each component used in the second step will be described in detail below.

[0108] <Crosslinking agent> Examples of the crosslinking agent include vulcanizing agents such as sulfur, sulfur halides, organic peroxides, quinone dioximes, organic polyamine compounds, alkylphenol resins having a methylol group, etc. Among these, sulfur is usually used as the crosslinking agent.

[0109] The proportion of the crosslinking agent used is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the polymer component. When the proportion of the crosslinking agent used is within the above range, the progress of crosslinking during kneading can be suppressed, and the physical properties of the resulting crosslinked polymer can be improved. When the vulcanizing agent described above is used as the crosslinking agent, a vulcanization accelerator can be used in combination.

[0110] <Acidic compounds> As the acidic compound, saturated fatty acids having 12 to 24 carbon atoms and their metal salts are preferably used. Specific examples of the acidic compound include lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, nonadecylic acid, arachidic acid, henicosylic acid, behenic acid, tricosylic acid, lignoceric acid, and calcium salts and zinc salts of these saturated fatty acids. These acidic compounds can be used alone or in combination of two or more. Among these, stearic acid is preferred. The proportion of the acidic compound used is preferably 0.3 to 15 parts by mass based on 100 parts by mass of the polymer component.

[0111] <Vulcanization aid> An example of the vulcanization aid is zinc oxide, etc. The proportion of the vulcanization aid used is preferably 1 to 5 parts by mass with respect to 100 parts by mass of the polymer component.

[0112] <Vulcanization accelerator> Examples of the vulcanization accelerator include guanidine-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, thiuram-based, dithiocarbamate-based, and xanthate-based compounds. Specific examples of preferred vulcanization accelerators include sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazylsulfenamide (CBS) and N-tetra-butyl-2-benzothiazylsulfenamide (TBBS). The proportion of the vulcanization accelerator used is appropriately determined in consideration of the type and proportion of the basic compound, and is preferably 0.5 to 5 parts by mass relative to 100 parts by mass of the polymer component.

[0113] 1.3.Effects The polymer composition obtained by the production method according to the present embodiment as described above is an unvulcanized polymer composition, and a crosslinked polymer is formed by subjecting it to a crosslinking treatment such as vulcanization.

[0114] In the method for producing a polymer composition according to the present embodiment, the conjugated diene polymer (A) and the basic compound (B) are kneaded together, and the resulting kneaded mixture is kneaded with a crosslinking agent. Therefore, even if the conjugated diene polymer (A) is blended as a polymer component, the processability can be improved while maintaining the excellent fuel economy performance of the conjugated diene polymer (A). In addition, when the resulting polymer composition contains a filler, the dispersibility of the filler can be improved.

[0115] Therefore, according to the method for producing a polymer composition according to the present embodiment, it is possible to obtain a polymer composition containing a conjugated diene polymer (A), which has excellent processability and, in the case where a filler is contained, has good dispersibility for the filler.

[0116] The effect of the method for producing a polymer composition according to this embodiment is remarkable when the conjugated diene polymer is a reaction product between an active polymerization terminal and a compound represented by any one of the above general formulas (1) to (3).

[0117] 1.4.Applications The crosslinked polymer formed from the polymer composition obtained by the production method according to the present embodiment is suitable for use as a tire, specifically as a tire tread. The tire thus obtained has high strength in the tread and a desired shape in the tread, so that excellent performance can be obtained. The crosslinked polymer can also be used as tire components other than the tread, anti-vibration rubber, fenders, belts, hoses, and other industrial products.

[0118] 2. Working Example Specific examples of the present invention will be described below, but the present invention is not limited to these examples. In the following Production Examples, Examples, and Comparative Examples, "%" is based on mass unless otherwise specified.

[0119] 2.1. (A) Production examples and physical property measurements of conjugated diene polymers <Production Example 1> In a nitrogen-purged autoclave reactor having an internal volume of 5 liters, 2500 g of cyclohexane, 50 g of tetrahydrofuran as a vinyl group content regulator (randomizer), and 125 g of styrene and 365 g of 1,3-butadiene as monomers were charged. After adjusting the temperature of the contents of the reactor to 10°C, 5.20 mmol of n-butyllithium was added as a polymerization initiator to start polymerization. The polymerization was carried out under adiabatic conditions, and the maximum temperature reached 85°C. When the polymerization conversion rate reached 99% (25 minutes after the start of polymerization), 10 g of 1,3-butadiene was added over 1 minute, and then 1.15 mmol of N-(3-imidazolylpropyl)-N,N-bis(3-triethoxysilylpropyl)amine was added as a modifier and reacted for 15 minutes. Just before adding the modifier, a sample was taken to measure the weight average molecular weight of the polymer before modification. 4.40 g of 2,6-di-tert-butyl-p-cresol was added as an antiaging agent to the polymer solution containing the modified conjugated diene copolymer obtained. Next, the solvent was removed by steam stripping, and the mixture was dried with a heated roll adjusted to 110°C to obtain a modified conjugated diene copolymer (hereinafter also referred to as "SBR-1").

[0120] <Production Example 2> In Production Example 1, the same operation was carried out except that 0.767 mmol of tris(3-triethoxysilylpropyl)amine was added instead of N-(3-imidazolylpropyl)-N,N-bis(3-triethoxysilylpropyl)amine, to obtain a modified conjugated diene copolymer (hereinafter also referred to as "SBR-2").

[0121] <Production Example 3> The same procedure was carried out as in Production Example 1, except that 0.575 mmol of N,N,N',N'-tetrakis(3-triethoxysilylpropyl)-1,3-diaminopropane was added instead of N-(3-imidazolylpropyl)-N,N-bis(3-triethoxysilylpropyl)amine, to obtain a modified conjugated diene copolymer (hereinafter also referred to as "SBR-3").

[0122] <Production Example 4> In Production Example 1, the same operation was carried out except that 0.767 mmol of 3-(2,2-diethoxy-1,2-azasilolidin-1-yl)-N,N-bis(3-(triethoxysilyl)propyl)propan-1-amine was added instead of N-(3-imidazolylpropyl)-N,N-bis(3-triethoxysilylpropyl)amine, to obtain a modified conjugated diene copolymer (hereinafter also referred to as "SBR-4").

[0123] <Production Example 5> The same procedure was carried out as in Production Example 1, except that 2.30 mmol of dimethyldiethoxysilane was added instead of N-(3-imidazolylpropyl)-N,N-bis(3-triethoxysilylpropyl)amine, to obtain a conjugated diene copolymer (hereinafter also referred to as "SBR-5").

[0124] <Bound styrene content (proportion of structural units derived from styrene)> 500MHz 1 The carbon black was determined by H-NMR.

[0125] <Vinyl group content> 500MHz 1 The carbon black was determined by H-NMR.

[0126] <Measurement of weight average molecular weight (Mw) before modification> Using gel permeation chromatography (GPC) ("HLC-8120" manufactured by Tosoh Corporation), the weight average molecular weight (Mw) in terms of polystyrene was calculated from the retention time corresponding to the apex of the maximum peak in the GPC curve obtained under the following GPC conditions: (GPC conditions) Column: 2 pieces of "GMHXL" (manufactured by Tosoh Corporation) Column temperature: 40℃ Mobile phase: Tetrahydrofuran Flow rate: 1.0ml / min Sample concentration: 10mg / 20ml

[0127] <Mooney viscosity> In accordance with JIS K6300-1, an L rotor was used, with 1 minute of preheating, 4 minutes of rotor operation, and a temperature of 100°C.

[0128] For the obtained conjugated diene polymers SBR-1 to SBR-5, the polymerization recipes are shown in Table 1 below, and the physical properties are shown in Table 2 below.

[0129] [Table 1]

[0130] [Table 2]

[0131] 2.2. Examples 1 to 3, 5 to 8 and Comparative Examples 1 to 6 A polymer composition was produced by blending the components according to the blending recipe shown in Table 3 below and kneading them. The kneading was carried out in the following manner.

[0132] In the first step (first stage mixing), a plastomill (capacity: 250 mL) equipped with a temperature control device was used to mix the components blended according to Table 3 below, i.e., all of the components to be used in the first step, at the same time, at a rotation speed of 60 rpm and a mixing time of 4 minutes.

[0133] Next, in the second step (second-stage kneading), the kneaded product obtained in the first step was cooled to room temperature, and then each component to be subjected to the second step was mixed in a plastomill equipped with a temperature control device according to Table 3 below, and kneaded under conditions of a rotation speed of 60 rpm and a kneading time of 1.5 minutes to obtain each polymer composition.

[0134] Next, each of the obtained polymer compositions was molded and vulcanization molded at 160° C. for a predetermined time in a vulcanization press to obtain each of the crosslinked polymers having a predetermined shape to be subjected to the following evaluation tests.

[0135] 2.3. Example 4 A polymer composition was produced by blending the components according to the blending recipe shown in Table 3 below and kneading them. The kneading was carried out in the following manner.

[0136] In the first step (first stage mixing) using a plastomill (capacity: 250 mL) equipped with a temperature control device, the components other than the silane coupling agent, which were mixed according to Table 3 below, were mixed at a rotation speed of 60 rpm for a mixing time of 2 minutes, and then the silane coupling agent was added and mixed, and further mixed at a rotation speed of 60 rpm for a mixing time of 2 minutes.

[0137] Next, in the second step (second-stage kneading), the kneaded product obtained in the first step was cooled to room temperature, and then each component to be subjected to the second step was mixed in a plastomill equipped with a temperature control device according to Table 3 below, and kneaded under conditions of a rotation speed of 60 rpm and a kneading time of 1.5 minutes to obtain each polymer composition.

[0138] Next, each of the obtained polymer compositions was molded and vulcanization molded at 160° C. for a predetermined time in a vulcanization press to obtain each of the crosslinked polymers having a predetermined shape to be subjected to the following evaluation tests.

[0139] 2.4.Evaluation Methodology The polymer compositions and crosslinked polymers obtained above were subjected to the following evaluation tests. The results are shown in Table 3 below.

[0140] <Processability evaluation test> The kneaded product obtained in the first step (first stage kneading) and the kneaded product obtained in the second step (second stage kneading) before vulcanization were used as measurement samples, and the Mooney viscosity (ML 1+4, 100°C) was measured. In Table 3 below, Mooney viscosity (ML 1+4 , 100°C) is shown as an index relative to the measured value in Comparative Example 1, which is set at 100. According to the index, a larger value indicates better processability.

[0141] <Low hysteresis loss performance (60℃ tan δ)> The crosslinked polymer obtained above was used as a measurement sample, and an ARES viscoelasticity tester (manufactured by TA Instruments) was used to measure 60° C. tan δ under conditions of a shear dynamic strain of 3.0%, an angular velocity of 100 radians per second, and a temperature of 60° C. Table 3 below shows an index when the measurement value of Comparative Example 1 is taken as 100, and according to the index, the larger the value, the smaller and more favorable the low hysteresis loss property.

[0142] <Filler dispersion> The crosslinked polymer obtained above was used as a measurement sample, and an ARES viscoelasticity tester (manufactured by TA Instruments) was used to measure the elastic modulus difference ΔG' between the elastic modulus at a dynamic shear strain of 0.1% and the elastic modulus at a dynamic shear strain of 10.0% at an angular velocity of 100 radians per second and a temperature of 50°C. Table 3 below shows the measured values ​​of the elastic modulus difference ΔG' as an index when the measured value in Comparative Example 1 is taken as 100. According to the index, the larger the value, the better the dispersibility of the filler.

[0143] 2.5.Evaluation Results Table 3 below shows the components and blending ratios used in each step in the production of each polymer composition, as well as the evaluation results.

[0144] [Table 3]

[0145] In Table 3, the numerical values ​​of each component in the polymer composition represent parts by mass. The following products were used as the materials shown in Table 3. Basic compound A: Tetrahydro-1,4-oxazine (morpholine), pKa=8.4, manufactured by Tokyo Chemical Industry Co., Ltd. Basic compound B: Ouchi Shinko Chemical Industry Co., Ltd., product name "Noccelaer D", 1,3-diphenylguanidine, pKa = 10.1 Basic compound C: Tokyo Chemical Industry Co., Ltd., aniline, pKa=4.6 Polybutadiene rubber: JSR Corporation, product name "BR-01" Extending oil: Japan Energy Corporation, product name "JOMO Process NC-140" Silica: Solvay, product name "ZEOSIL 1165MP" Silane coupling agent: Evonik, product name "Si75", bis(3-triethoxysilylpropyl) disulfide Anti-aging agent: Seiko Chemical Co., Ltd., product name "Ozonone 6C", N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine Stearic acid: NOF Corporation, product name "Beads Stearic Acid Tsubaki" Zinc oxide: Manufactured by Mitsui Mining & Smelting Co., Ltd., product name "Zinc Oxide No. 1" Vulcanization accelerator D: Ouchi Shinko Chemical Industry Co., Ltd., product name "Noccelaer D", 1,3-diphenylguanidine Vulcanization accelerator CZ: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Noccela CZ", N-cyclohexyl-2-benzothiazolyl sulfenamide Sulfur: Tsurumi Chemical Industry Co., Ltd., product name "Kinka-in oil-filled fine powder sulfur"

[0146] From the results in Table 3 above, it was confirmed that the methods for producing the polymer compositions according to Examples 1 to 8 provide polymer compositions with excellent processability and excellent filler dispersibility, and further, it was confirmed that the crosslinked polymers formed from the polymer compositions have excellent low hysteresis loss properties.

[0147] It was also confirmed that by providing an acidic compound in the second step as in the production methods of the polymer compositions of Examples 3 to 4 and 6, or by post-adding a silane coupling agent as in the production method of the polymer composition of Example 4, the processability and dispersibility of the filler were further improved, and the crosslinked polymer formed from the polymer composition had better low hysteresis loss properties.

[0148] The present invention is not limited to the above-described embodiments, and various modifications are possible. The present invention includes configurations that are substantially the same as those described in the embodiments (for example, configurations with the same functions, methods, and results, or configurations with the same purpose and effect). The present invention also includes configurations in which non-essential parts of the configurations described in the above-described embodiments are replaced with other configurations. Furthermore, the present invention also includes configurations that have the same effects as the configurations described in the above-described embodiments, or that can achieve the same purpose. Furthermore, the present invention also includes configurations in which publicly known technology is added to the configurations described in the above-described embodiments.

Claims

1. A first step of kneading (A) a conjugated diene polymer, which is a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound, and which is a reaction product of an active polymerization terminal and a compound represented by any one of the following general formulas (1) to (2), and (B) a basic compound having an acid dissociation constant of 8.0 or more; A second step of kneading the kneaded product obtained in the first step with a crosslinking agent; The method for producing a polymer composition comprising the steps of: 【Chemistry 1】 (In formula (1), A ２ is an imino group, an amide group, a (thio)carbonyl group, a (thio)carbonyloxy group, a sulfide or a polysulfide; ２ or represents a protected primary amino group, a protected secondary amino group, a tertiary amino group, a nitrile group, a pyridyl group, a (thio)epoxy group, a (thio)isocyanate group, a (thio)formyl group, a (thio)carboxylate ester, a metal salt of a (thio)carboxylate ester, a carboxylic acid halide, or an imidazolyl group; L ２ and L ３ each independently represents a single bond or a hydrocarbylene group having 1 to 20 carbon atoms; R ３ and R ４ each independently represents a hydrocarbyl group having 1 to 4 carbon atoms, n2 is 0 to 2, and m1 is 1. 【Chemistry 4】 (In formula (2), A ３ each independently represents an imino group, an amide group, a secondary amino group, or a tertiary amino group; Z represents a t-valent group having 1 to 20 carbon atoms which may or may not contain a nitrogen atom; L ４ represents a single bond or a hydrocarbylene group having 1 to 20 carbon atoms; L ５ represents a hydrocarbylene group having 1 to 20 carbon atoms; R ５ and R ６ each independently represents a hydrocarbyl group having 1 to 4 carbon atoms, n3 is 0 or 1, and t is 2 or 3.

2. The method for producing a polymer composition according to claim 1 , wherein the basic compound having an acid dissociation constant of 8.0 or more is an amine compound.

3. The method for producing a polymer composition according to claim 1 or 2, wherein the basic compound having an acid dissociation constant of 8.0 or more is a guanidine compound.

4. The method for producing a polymer composition according to claim 1 , wherein in the second step, an acidic compound is kneaded together with the kneaded mixture and the crosslinking agent.

5. The method for producing a polymer composition according to claim 4, wherein the acidic compound is a saturated fatty acid having 12 to 24 carbon atoms.

6. 6. The method for producing a polymer composition according to claim 1, wherein in the first step, silica is kneaded together with the conjugated diene polymer and the basic compound having an acid dissociation constant of 8.0 or more.

7. 7. The method for producing a polymer composition according to claim 6, wherein in the first step, the conjugated diene polymer, the basic compound having an acid dissociation constant of 8.0 or more, and the silica are kneaded together, and then a silane coupling agent is added and further kneaded.

8. The method for producing a polymer composition according to any one of claims 1 to 7, wherein the crosslinking agent is sulfur.

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