Modified conjugated diene-based polymer, method for producing same, polymer composition, crosslinked body, and tire

Abstract

This modified conjugated diene-based polymer has a weight average molecular weight (Mw), as measured by GPC, of 10×104-200×104 and in which molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) relative to the number average molecular weight (Mn) is 1.40-4.00, the modification ratio is 80% or more relative to the total amount of the polymer, the modification ratio of high molecular weight components having molecular weights not less than the weight average molecular weight, as measured by GPC, is 50% or more, and the modification ratio of low molecular weight components having molecular weights not higher than the number average molecular weight, as measured by GPC, is 50% or more.

Description

Modified conjugated diene polymers and methods for producing the same, polymer compositions, crosslinked materials and tires

[0001] [Cross-reference of related applications] This application claims priority under Japanese Patent Application No. 2025-50579, filed on 25 March 2025, which is incorporated herein by reference in its entirety. This disclosure relates to modified conjugated diene polymers and methods for producing the same, polymer compositions, crosslinked materials and tires.

[0002] Conjugated diene polymers obtained by polymerization using conjugated diene compounds have excellent properties such as heat resistance, wear resistance, mechanical strength, and moldability, and are therefore widely used in various industrial products such as pneumatic tires, vibration-damping rubber, and hoses.

[0003] In rubber compositions used for the treads and sidewalls of pneumatic tires, it is known that fillers such as carbon black and silica are blended with conjugated diene polymers to improve the durability and wear resistance of the product. Furthermore, it has been conventionally proposed to use modified conjugated diene polymers in which heteroatoms such as silicon, nitrogen, oxygen, sulfur, and phosphorus are introduced into the conjugated diene polymer to increase the affinity between the conjugated diene polymer and the filler (see, for example, Patent Documents 1 to 3).

[0004] International Publication No. 2008 / 123164, Japanese Patent Publication No. Hei 11-349632, International Publication No. 2017 / 221943

[0005] With the trend towards electrification of automobiles, vehicle weight is also increasing, and the rubber used in automobile tires is required to have greater wear resistance than ever before. Furthermore, with the growing awareness of environmental issues among society and consumers, a higher level of fuel efficiency is also being demanded.

[0006] This disclosure has been made in view of the above-mentioned problems, and one of its objectives is to provide a modified conjugated diene polymer that can obtain a crosslinked body with excellent fuel efficiency and wear resistance.

[0007] According to this disclosure, in one embodiment, a modified conjugated diene polymer having a weight-average molecular weight (Mw) of 10 × 10 as measured by gel permeation chromatography (GPC) ４ The above 200 x 10 ４ A modified conjugated diene polymer is provided, which is as follows: the molecular weight distribution (Mw / Mn), expressed as the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn), is 1.40 or more and 4.00 or less; the modification rate with respect to the total amount of the modified conjugated diene polymer is 80% or more; the modification rate of the high molecular weight component of the modified conjugated diene polymer that is equal to or greater than the weight-average molecular weight measured by GPC is 50% or more; and the modification rate of the low molecular weight component of the modified conjugated diene polymer that is equal to or less than the number-average molecular weight measured by GPC is 50% or more.

[0008] In another embodiment, the present disclosure provides a polymer composition comprising the above-mentioned modified conjugated diene polymer and a filler. In yet another embodiment, the present disclosure provides a crosslinked body obtained by crosslinking the polymer composition. Furthermore, in yet another embodiment, the present disclosure provides a tire in which a tread, a sidewall, or both are formed using the polymer composition.

[0009] According to this disclosure, in another embodiment, a method for producing the above-mentioned modified conjugated diene polymer is provided, comprising the step of polymerizing a monomer containing a conjugated diene compound by a batch polymerization method in the presence of a polymerization initiator, wherein the polymerization initiator is added to the reactor in multiple divided steps during polymerization. In yet another embodiment, a method for producing the above-mentioned modified conjugated diene polymer is provided, comprising the step of polymerizing a monomer containing a conjugated diene compound by a continuous polymerization method in the presence of a polymerization initiator.

[0010] By using the modified conjugated diene polymer of this disclosure, a crosslinked body with excellent fuel efficiency and wear resistance can be obtained.

[0011] Figure 1 illustrates the method for calculating the modification rate of a modified conjugated diene polymer. Figure 2 illustrates the method for calculating the modification rates of the high molecular weight component and the low molecular weight component of a modified conjugated diene polymer.

[0012] The following describes in detail matters relating to the aspects of this disclosure. It should be understood that the present invention is not limited to the embodiments described below, but also includes various modifications that do not alter the essence of the invention. In this specification, the numerical range "X to Y" represents a numerical range that includes the numerical value X as the lower limit and the numerical value Y as the upper limit.

[0013] The term "(meth)acrylic acid" is a concept that includes both "acrylic acid" and "methacrylic acid." The term "(modified) conjugated diene polymer" is a term that includes both unmodified conjugated diene polymers and modified conjugated diene polymers (i.e., modified conjugated diene polymers). In the following, when simply referred to as "conjugated diene polymer," that "conjugated diene polymer" may be either an unmodified or a modified conjugated diene polymer, unless otherwise specified.

[0014] ≪Modified Conjugated Diene Polymers≫ The modified conjugated diene polymers of this disclosure (hereinafter also referred to as "modified conjugated diene polymers (P)") are aggregates of polymers having structural units derived from conjugated diene compounds, and 80% or more of the total amount is modified. That is, the modified conjugated diene polymers (P) contain molecules having structural units derived from conjugated diene compounds, and at least a portion of the constituent molecules have functional groups containing heteroatoms (such as nitrogen, oxygen, silicon, phosphorus, sulfur, etc.). When the modification rate of the modified conjugated diene polymers (P) is less than 100%, the modified conjugated diene polymers (P) contain unmodified molecules.

[0015] The method of modifying the modified conjugated diene polymer (P) is not particularly limited. That is, the modified conjugated diene polymer (P) may be obtained by end modification, by main chain modification, or by using both end modification and main chain modification. Here, end modification refers to a modification method in which a functional group containing a heteroatom is introduced to the polymerization start end or polymerization end of the conjugated diene polymer using a modifying agent. Main chain modification refers to a modification method in which a monomer containing a heteroatom is copolymerized, or a functional group containing a heteroatom is introduced to the main chain of the polymer by reacting the conjugated diene polymer with a modifying agent. When a functional group containing a heteroatom is introduced to the main chain of the polymer by reacting the conjugated diene polymer with a modifying agent, the functional group containing the heteroatom will be present in the side chains of the polymer. A "modifying agent" is a chemical substance that causes modification. In this specification, a modifying agent that modifies the polymerization initiation end of a conjugated diene polymer is also referred to as an "initiation end modifying agent," and a modifying agent that modifies the polymerization termination end of a conjugated diene polymer is also referred to as an "termination end modifying agent."

[0016] The molecular structure of the modified conjugated diene polymer (P) is not particularly limited. That is, the modified conjugated diene polymer (P) may be an aggregate of linear polymers, an aggregate of branched polymers, or a mixture of linear and branched polymers. In terms of the high effect of improving the rolling resistance and wear resistance of the crosslinked material obtained using the modified conjugated diene polymer (P), it is preferable that the modified conjugated diene polymer (P) is an aggregate of linear polymers.

[0017] The monomers constituting the modified conjugated diene polymer (P) are not particularly limited as long as they include a conjugated diene compound. The modified conjugated diene polymer (P) may be a homopolymer of a conjugated diene compound, or it may be a copolymer of a conjugated diene compound and a monomer different from the conjugated diene compound.

[0018] Examples of conjugated diene compounds 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. The conjugated diene compound may be used individually or in combination of two or more.

[0019] When the modified conjugated diene polymer (P) is a copolymer, it is preferable that the modified conjugated diene polymer (P) is a copolymer of a conjugated diene compound and an aromatic vinyl compound, from the viewpoint of increasing the strength of the crosslinked material (i.e., rubber) obtained using the modified conjugated diene polymer (P).

[0020] Examples of aromatic vinyl compounds include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, vinylxylene, vinylnaphthalene, diphenylethylene, methoxystyrene, t-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 4-dimethylaminostyrene, and 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene. Of these, styrene and α-methylstyrene are preferred aromatic vinyl compounds. One aromatic vinyl compound may be used alone, or two or more may be used in combination.

[0021] When the modified conjugated diene polymer (P) is a copolymer of a conjugated diene compound and an aromatic vinyl compound, it is preferable that the copolymer contains 1,3-butadiene and styrene in its monomer composition, as this provides high living properties in anionic polymerization. It is preferable that the modified conjugated diene polymer (P) is a random copolymer mainly composed of random copolymer portions where the distribution of the conjugated diene compound and the aromatic vinyl compound is irregular, as this allows for a balanced improvement of hysteresis loss at both low and high temperatures. Furthermore, when the modified conjugated diene polymer (P) is a random copolymer, the random copolymer may further have block portions at its ends consisting of the conjugated diene compound or the aromatic vinyl compound. In the modified conjugated diene polymer (P), the proportion of monomers constituting the random copolymer portion is preferably 65% ​​by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, based on the total amount of monomers used in the polymerization of the modified conjugated diene polymer (P).

[0022] The proportion of structural units derived from aromatic vinyl compounds in the modified conjugated diene polymer (P) is preferably 3 to 55% by mass of the total amount of structural units contained in the modified conjugated diene polymer (P), from the viewpoint of balancing rolling resistance (low fuel consumption performance) and wet skid resistance of the crosslinked material obtained using the modified conjugated diene polymer (P), and improving wear resistance. The proportion of structural units derived from aromatic vinyl compounds is more preferably 5% by mass or more. Furthermore, the proportion of structural units derived from aromatic vinyl compounds is more preferably 50% by mass or less, and even more preferably 45% by mass or less. The content ratio of structural units derived from aromatic vinyl compounds in the polymer is １ This is a value measured by 1H-NMR.

[0023] The polymer chain of the modified conjugated diene polymer (P) may contain structural units derived from monomers other than conjugated diene compounds and aromatic vinyl compounds (hereinafter also referred to as "other monomers"). Examples of other monomers include acrylonitrile, methyl (meth)acrylate, and ethyl (meth)acrylate. In the modified conjugated diene polymer (P), the proportion of structural units derived from other monomers is preferably 10% by mass or less, and more preferably 5% by mass or less, relative to the total amount of structural units contained in the modified conjugated diene polymer (P), from the viewpoint of achieving a good balance between the low hysteresis loss characteristics and wet skid resistance of the crosslinked material obtained using the modified conjugated diene polymer (P), and from the viewpoint of improving abrasion resistance.

[0024] In order to obtain a crosslinked material with excellent rolling resistance, it is preferable that the modified conjugated diene polymer (P) contains a molecule having at least one selected from the group consisting of silicon atoms, nitrogen atoms, and oxygen atoms. In order to further enhance the effect of improving the rolling resistance of the crosslinked material, it is preferable that the modified conjugated diene polymer (P) has silicon atoms, nitrogen atoms, or both, and it is more preferable that it has silicon atoms and nitrogen atoms.

[0025] The silicon content in the modified conjugated diene polymer (P) (hereinafter also referred to as "silicon content") is preferably 70 ppm or more, in order to sufficiently obtain the effect of improving the rolling resistance and wear resistance of the crosslinked material obtained using the modified conjugated diene polymer (P). The silicon content of the modified conjugated diene polymer (P) is more preferably 80 ppm or more, even more preferably 100 ppm or more, and particularly preferably 120 ppm or more. Furthermore, from the viewpoint of ensuring processability, the silicon content of the modified conjugated diene polymer (P) is preferably 700 ppm or less, more preferably 600 ppm or less, even more preferably 500 ppm or less, and particularly preferably 350 ppm or less. In this specification, the silicon content of the polymer is a value measured by inductively coupled plasma mass spectrometry (ICP-MS).

[0026] The nitrogen atom content (hereinafter also referred to as "nitrogen content") in the modified conjugated diene polymer (P) is preferably 70 ppm or more from the viewpoint that sufficient improvement effects on rolling resistance and wear resistance of a crosslinked product obtained by using the modified conjugated diene polymer (P) can be obtained. The nitrogen content of the modified conjugated diene polymer (P) is more preferably 80 ppm or more, still more preferably 100 ppm or more, and particularly preferably 120 ppm or more. Further, the nitrogen content of the modified conjugated diene polymer (P) is preferably 700 ppm or less, more preferably 600 ppm or less, still more preferably 500 ppm or less, and particularly preferably 300 ppm or less. In the present specification, the nitrogen content of a polymer is a value measured by a trace total nitrogen analyzer in accordance with JIS-2609:1998.

[0027] In addition to the ease of production of the modified conjugated diene polymer (P), the modified conjugated diene polymer (P) is preferably obtained by terminal modification with a modifying agent from the viewpoint that the rolling resistance and wear resistance of a crosslinked product obtained using the modified conjugated diene polymer (P) can be further improved. As the modifying agent, a compound (M) having a silicon atom can be preferably used. Further, the modified conjugated diene polymer (P) obtained by using the compound (M) preferably includes a molecule having a partial structure derived from the compound (M) at at least one terminal of the polymer chain. From the viewpoint that a crosslinked product more excellent in rolling resistance can be obtained, the compound (M) preferably further has a nitrogen atom.

[0028] Preferable specific examples of the compound (M) include compounds represented by the following formula (1). (In formula (1), X １ is a group represented by the following formula (1-1) or formula (1-2). A １ is an (i+k)-valent hydrocarbon group having 1 to 20 carbon atoms, or an (i+k)-valent group having 1 to 20 carbon atoms that contains one or both of nitrogen and oxygen atoms, has no active hydrogen, and is bonded to each of X １ and the group "-Si(R １ ) ｎ (OR ２ ) ３－ｎ " via a carbon atom. R１ and R ２ These are hydrocarbyl groups having 1 to 20 carbon atoms, independently of each other. n is an integer from 0 to 2. If n is 0 or 1, multiple ORs are used. ２ They are the same or different. If n is 2, there are multiple R １ They are the same or different. i and k are independent integers from 1 to 6, provided that i + k ≤ 10. In equation (1), if i is 2 or greater, multiple X １ They are the same or different. If k is 2 or more, there are multiple groups "-Si(R １ ) ｎ (OR ２ ) ３－ｎ (These are either the same or different.) (In formula (1-1), R ５ R is a monovalent group having a structure in which a hydrogen atom, a C1-C8 alkyl halide, or an aromatic ring to which a halogen atom or methyl group is bonded. ６ and R ７ These are hydroxylene groups with 1 to 10 carbon atoms, independently of each other. Q １ and Q ２ These are nitrogen atoms or -CR atoms, independently of each other. １０ -. However, R ５ If Q is a hydrogen atom, １ R is a nitrogen atom. １０ R is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms. * represents a bond. In formula (1-2), R ８ R is a monovalent group having a structure in which a hydrogen atom, a C1-C8 alkyl halide, or an aromatic ring to which a halogen atom or methyl group is bonded. ９ R is a hydrocarbyl group or trihydrocarbyl silyl group having 1 to 20 carbon atoms. ８ If R is a hydrogen atom, ９ This is a hydrocarbyl group with 1 to 20 carbon atoms. (* represents a bond.)

[0029] The compound represented by formula (1) above (hereinafter also referred to as "compound (MA)") can function as an initiation end modifier that modifies the polymerization initiation end of a conjugated diene polymer. Therefore, in the production of a modified conjugated diene polymer (P), by polymerizing a monomer containing a conjugated diene compound in the presence of a compound obtained by mixing compound (MA) with at least one selected from the group consisting of alkali metal compounds and alkaline earth metal compounds as polymerization initiators, a substructure derived from compound (MA) can be introduced to the polymerization initiation end of a polymer chain containing structural units derived from the conjugated diene compound. In the following, the compound obtained by mixing compound (MA) with at least one selected from the group consisting of alkali metal compounds and alkaline earth metal compounds will also be referred to as a "metal silane compound".

[0030] In the above equation (1), X １ If the base is represented by formula (1-1), then R ６ and R ７ The 1-10 carbon dioxide hydrocarbylene group represented by is preferably a linear or branched alkanediyl group having 1-20 carbon atoms, and more preferably a methylene group or an ethylene group.

[0031] Q １ and Q ２ The group represented by -CR １０ - If R １０ The C1-C20 hydrocarbyl group represented by is preferably a linear or branched alkyl group having C1-C10, and more preferably an alkyl group having C1-C3. １０ Of these, hydrogen atoms or methyl groups are preferred.

[0032] From the perspective of improving the rolling resistance of the resulting cross-linked material, Q １ and Q ２ Preferably, at least one of them is a nitrogen atom, Q １ and Q ２ It is more preferable that both are nitrogen atoms. Q is preferable in that a crosslinked material with superior rolling resistance can be obtained. １ and Q ２ Q ２Is it a tertiary nitrogen atom, or Q １ and Q ２ It is particularly preferable that both atoms are tertiary nitrogen atoms.

[0033] In equations (1-1) and (1-2), R ５ and R ８ Examples of C1-C8 halogenated alkyl groups represented by include groups in which any hydrogen atom of the C1-C8 alkyl group is substituted with a halogen atom. The C1-C8 alkyl group substituted with the halogen atom may be linear or branched. The alkyl group is preferably a C1-C6 alkyl group, and more preferably a C1-C4 alkyl group. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms, with chlorine or bromine atoms being preferred.

[0034] R ５ or R ８ The group represented by is a monovalent group having a structure in which a halogen atom or a methyl group is bonded to an aromatic ring (hereinafter referred to as "cyclic group R"). Ｃ It is also called "." ) In the case of the cyclic group R Ｃ Examples of aromatic rings present include benzene rings, naphthalene rings, and anthracene rings, with benzene rings or naphthalene rings being preferred. Cyclic group R Ｃ In this, the aromatic ring may further have substituents other than halogen atoms and methyl groups. Examples of such substituents include N,N-dialkylamino groups. Examples of halogen atoms bonded to the aromatic ring include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. Of these, chlorine atoms or bromine atoms are preferred, and bromine atoms are more preferred.

[0035] R ５ or R ８ The group represented is a cyclic group R ＣSpecific examples of this include 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 2-bromophenyl group, 3-bromophenyl group, 4-bromophenyl group, 2-N,N-dimethylamino-3-methylphenyl group, 2-N,N-dimethylamino-4-methylphenyl group, 2-N,N-dimethylamino-5-methylphenyl group, 2-methyl-3-N,N-dimethylaminophenyl group, 3-N,N-dimethylamino-4-methylphenyl group, 3- Examples include N,N-dimethylamino-5-methylphenyl group, 2-N,N-dimethylamino-3-bromophenyl group, 2-N,N-dimethylamino-4-bromophenyl group, 2-N,N-dimethylamino-5-bromophenyl group, 2-bromo-3-N,N-dimethylaminophenyl group, 3-N,N-dimethylamino-4-bromophenyl group, 3-N,N-dimethylamino-5-bromophenyl group, 5-bromonaphthalenyl group, and 5-bromoanthracenyl group.

[0036] From the viewpoint of increasing the reactivity between the polymerization initiator and the compound (MA), R ５ This consists of a hydrogen atom and a cyclic group R. Ｃ Alternatively, it is preferably a C1-C8 halogenated alkyl group, more preferably a monovalent cyclic group having a structure in which a hydrogen atom and a bromine atom are bonded to an aromatic ring, a C1-C8 bromoalkyl group, or a C1-C8 chloroalkyl group. ８ is a cyclic base R Ｃ Alternatively, it is preferably a C1-C8 halogenated alkyl group, more preferably a monovalent cyclic group having a structure in which a bromine atom is bonded to an aromatic ring, a C1-C8 bromoalkyl group, or a C1-C8 chloroalkyl group.

[0037] R ９ The C1-C20 hydrocarbyl group represented by is preferably a C1-C20 alkyl group, and more preferably a C1-C20 linear or branched alkyl group. Examples of trihydrocarbylsilyl groups include trimethylsilyl group and triethylsilyl group.

[0038] X １ From the viewpoint of increasing the reactivity between X and the polymerization initiator, １It is preferable that the group is represented by the above formula (1-1). Furthermore, X is preferable in that a crosslinked body with superior rolling resistance can be obtained. １ It is more preferable that the molecule has a nitrogen-containing heterocycle, and even more preferable that it has a nitrogen-containing heterocycle containing a tertiary nitrogen atom in its ring skeleton.

[0039] A １ Examples of groups where the group is an (i+k) valent hydrocarbyl group include groups obtained by removing (i+k) hydrogen atoms from a chain hydrocarbon having 1 to 20 carbon atoms, an alicyclic hydrocarbon having 3 to 20 carbon atoms, or an aromatic hydrocarbon having 6 to 20 carbon atoms. Of these, the group obtained by removing (i+k) hydrogen atoms from a chain hydrocarbon is preferred.

[0040] A １ However, specific examples of a C1-C20 (i+k) valence group having one or both nitrogen and oxygen atoms and no active hydrogen include (i+k) valence heterocyclic groups and (i+k) valence groups having a tertiary amine structure. The heterocyclic group is preferably a conjugated system, and examples include monocyclic or fused rings such as pyridine, pyrimidine, pyrazine, quinoline, naphthyridine, and furan, or groups obtained by removing (i+k) hydrogen atoms from the ring portion of a structure in which multiple such monocyclic or fused rings are linked together. From the viewpoint of improving the processability when the polymer composition contains a modified conjugated diene polymer (P), (i+k) is preferably 2 to 6.

[0041] A １ The base is "-Si(R １ ) ｎ (OR ２ ) ３－ｎ " and X １ Each of them is bonded with a carbon atom. In terms of obtaining a crosslinked material with superior rolling resistance, A １ The base is "-Si(R １ ) ｎ (OR ２ ) ３－ｎ " and X １ It is preferable that each of these is bonded to the same or different carbon atoms constituting the hydrocarbon group. The hydrocarbon group is preferably a hydrocarbylene group, and more preferably an alkanediyl group.

[0042] R １ and R ２ Examples of C1-C20 hydrocarbyl groups represented by include C1-C20 alkyl groups, C3-C20 cycloalkyl groups, C2-C20 alkenyl groups, and C6-C20 aryl groups. １ and R ２ The alkyl group is preferably a linear or branched alkyl group having 1 to 20 carbon atoms, and more preferably a linear or branched alkyl group having 1 to 12 carbon atoms.

[0043] Specific examples of compound (MA) include the compounds represented by formulas (M1-1) to (M1-50) below, and compounds obtained by replacing the methyl group bonded to the silicon atom in these compounds with an alkyl group having 2 to 6 carbon atoms.

[0044] In a modified conjugated diene polymer (P), if a portion of the polymer chain ends have a substructure derived from compound (MA), the ends other than those having the substructure derived from compound (MA) may be modified or unmodified. If the ends other than those having the substructure derived from compound (MA) are modified, it is preferable that the ends have a substructure derived from a compound that has one or more functional groups selected from the group consisting of an amino group, a group having a carbon-nitrogen double bond, a nitrogen-containing heterocyclic group, a phosphino group, a cyclic ether group, a cyclic thioether group, a protected hydroxyl group, a protected thiol group, and a hydrocarbyloxysilyl group, and that can react with the polymerization active end, and it is more preferable that the substructure is derived from a compound having a hydrocarbyloxysilyl group.

[0045] <Properties of Modified Conjugated Diene Polymers (P)> Next, we will explain the properties of modified conjugated diene polymers (P).

[0046] (Mooney viscosity) The modified conjugated diene polymer (P) preferably has a Mooney viscosity of 20 or more and 150 or less when measured at 100°C. When the Mooney viscosity of the modified conjugated diene polymer (P) measured at 100°C is 20 or more, the wear resistance and rolling resistance of the crosslinked material obtained using the modified conjugated diene polymer (P) can be improved in a well-balanced manner. Furthermore, when the Mooney viscosity of the modified conjugated diene polymer (P) measured at 100°C is 150 or less, the processability of the modified conjugated diene polymer (P) tends to be sufficiently ensured. From the above viewpoint, the Mooney viscosity of the modified conjugated diene polymer (P) measured at 100°C is more preferably 25 or more, and even more preferably 30 or more. Furthermore, the Mooney viscosity of the modified conjugated diene polymer (P) measured at 100°C is more preferably 120 or less, even more preferably 100 or less, and even more preferably 80 or less. The Mooney viscosity of the modified conjugated diene polymer (P) is measured according to JIS K6300-1:2013.

[0047] (Vinyl Content) The vinyl content of the modified conjugated diene polymer (P) is preferably 10 to 70 mol%. A vinyl content of 10 mol% or more improves the grip properties of the crosslinked material obtained using the modified conjugated diene polymer (P). Furthermore, a vinyl group content of 70 mol% or less of the modified conjugated diene polymer (P) sufficiently suppresses the decrease in abrasion resistance of the crosslinked material obtained using the modified conjugated diene polymer (P). The vinyl content of the modified conjugated diene polymer (P) is more preferably 12 mol% or more, and even more preferably 15 mol% or more. Furthermore, the vinyl content of the modified conjugated diene polymer (P) is more preferably 60 mol% or less, even more preferably 50 mol% or less, and particularly preferably 45 mol% or less. In this specification, "vinyl content" refers to the percentage of structural units having 1,2-bonds relative to the total structural units of butadiene in the conjugated diene polymer. １ This is a value measured by 1H-NMR.

[0048] (Content ratio of structural units derived from aromatic vinyl compound) When the modified conjugated diene-based polymer (P) has structural units derived from an aromatic vinyl compound, the content ratio of structural units derived from an aromatic vinyl compound in the modified conjugated diene-based polymer (P) is, from the viewpoint of improving the balance between rolling resistance and wet skid resistance of the crosslinked product obtained using the modified conjugated diene-based polymer (P), preferably 3 to 55% by mass relative to the total amount of structural units contained in the modified conjugated diene-based polymer (P). The content ratio of structural units derived from an aromatic vinyl compound in the modified conjugated diene-based polymer (P) is more preferably 5% by mass or more, still more preferably 10% by mass or more, and particularly preferably 15% by mass or more. Further, the content ratio of structural units derived from an aromatic vinyl compound in the modified conjugated diene-based polymer (P) is more preferably 50% by mass or less, and still more preferably 45% by mass or less. The content ratio of structural units derived from an aromatic vinyl compound in the conjugated diene-based polymer is １ a value measured by 1H-NMR.

[0049] (Weight average molecular weight) For the modified conjugated diene-based polymer (P), the polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) is 10×10 ４ or more and 200×10 ４ or less. When the Mw of the modified conjugated diene-based polymer (P) is less than 10×10 ４ , the abrasion resistance and rolling resistance of the crosslinked product may be insufficient. Further, when the Mw of the modified conjugated diene-based polymer (P) exceeds 200×10 ４ , sufficient processability of the polymer composition containing the modified conjugated diene-based polymer (P) may not be ensured. From the viewpoint of obtaining a crosslinked product with excellent abrasion resistance and sufficiently low rolling resistance, the Mw of the modified conjugated diene-based polymer (P) is more preferably 15×10 ４ or more, still more preferably 20×10 ４ or more, and particularly preferably 25×10 ４ or more. Further, from the viewpoint of processability, the Mw of the modified conjugated diene-based polymer (P) is more preferably 150×10 ４ or less, and still more preferably 100×10 ４The following applies. Note that the weight-average molecular weight (Mw) of conjugated diene polymers represents the weight-average molecular weight (total weight-average molecular weight) based on all peaks of the molecular weight distribution curve (GPC curve) measured by GPC.

[0050] (Molecular Weight Distribution) For modified conjugated diene polymers (P), the molecular weight distribution (Mw / Mn), expressed as the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn), measured using GPC, is between 1.40 and 4.00. If the molecular weight distribution (Mw / Mn) is less than 1.40, processability and productivity tend to be poor. If the molecular weight distribution (Mw / Mn) exceeds 4.00, the wear resistance and rolling resistance of the crosslinked material may be insufficient. The molecular weight distribution (Mw / Mn) of modified conjugated diene polymers (P) is preferably 1.42 or higher, and more preferably 1.45 or higher. Furthermore, the molecular weight distribution (Mw / Mn) is preferably 3.50 or lower, more preferably 3.00 or lower, and even more preferably 2.80 or lower. The molecular weight distribution can be adjusted to the desired range by adjusting the timing and number of times polymerization initiators are added, or by employing a continuous polymerization method. For example, the molecular weight distribution tends to become larger when the polymerization initiator is added in multiple stages.

[0051] (Revision rate relative to the total amount of modified conjugated diene polymer) The modified conjugated diene polymer (P) has a revision rate (hereinafter also referred to as "revision rate αT") of 80% or more relative to the total amount of modified conjugated diene polymer (P). If the revision rate αT of the modified conjugated diene polymer (P) is less than 80%, the resulting crosslinked material cannot be improved in a balanced manner between wear resistance and rolling resistance. From the viewpoint of obtaining a crosslinked material in which wear resistance and rolling resistance are improved in a balanced manner, the revision rate αT of the modified conjugated diene polymer (P) is preferably 82% or more, more preferably 83% or more, and even more preferably 85% or more. Furthermore, from the viewpoint of maintaining good processability of the modified conjugated diene polymer (P), the revision rate αT of the modified conjugated diene polymer (P) is preferably 99% or less, and more preferably 98% or less.

[0052] Here, the denaturation rate αT of the denatured conjugated diene polymer (P) is the ratio (mass ratio) of the denatured component to the total amount of the denatured conjugated diene polymer (the sum of the denatured and undenatured components), which is a molecular aggregate. In this specification, the denaturation rate αT of the denatured conjugated diene polymer (P) is a value obtained by separating the denatured and undenatured components contained in the denatured conjugated diene polymer (P) by chromatography and quantifying the separated undenatured component.

[0053] In this specification, "modified component" refers to a polymer component having a functional group containing a heteroatom (such as nitrogen, oxygen, silicon, phosphorus, or sulfur) at its terminal or side chain, regardless of the modification method. For example, a component in which only the polymerization initiation end is modified, a component in which only the polymerization termination end is modified, and a component in which both the polymerization initiation end and the polymerization termination end are modified are all considered "modified components." On the other hand, "unmodified component" refers to a polymer component that does not have a functional group containing a heteroatom. For example, if a modified conjugated diene polymer (P) contains, as a modified component, a first component in which only the polymerization initiation end is modified, a second component in which only the polymerization termination end is modified, and a third component in which both the polymerization initiation end and the polymerization termination end are modified, the ratio of the sum of the first to third components to the total amount of the modified conjugated diene polymer (P) corresponds to the "modification rate αT" of that modified conjugated diene polymer (P).

[0054] More specifically, the denaturation rate αT of a modified conjugated diene polymer is determined by chromatography using a linked column, which consists of an adsorption column for adsorbing heteroatom-containing functional groups introduced into the conjugated diene polymer and a gel permeation chromatography (GPC) column connected in series. The modified and unmodified components in the sample are separated, and the separated unmodified component is quantified. The details of the method for measuring the denaturation rate αT using the adsorption column are described in the examples below.

[0055] The modification rate αT of a modified conjugated diene polymer (P) can be adjusted to a desired range by adjusting the type and amount of the starting end modifier or the type and amount of the stopping end modifier. Starting end modifiers or stopping end modifiers having a hydrocarbyloxysilyl group are preferred because they make it easy to adjust the modification rate αT of the modified conjugated diene polymer (P). In this specification, GPC measurement performed by connecting an adsorption column (e.g., a silica column) and a GPC column (e.g., a polystyrene column) in series is also referred to as "adsorption GPC measurement." In contrast, GPC measurement for determining the weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of a polymer is also referred to as "ordinary GPC measurement." The weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of a modified conjugated diene polymer (P) are values ​​that can be obtained by ordinary GPC measurement.

[0056] (Modification rate of high molecular weight components) The modified conjugated diene polymer (P) has a modification rate of 50% or more of high molecular weight components (hereinafter also referred to as "modification rate αH of high molecular weight components") of 50% or more, which is equal to or greater than the weight-average molecular weight (Mw) measured by GPC (i.e., normal GPC measurement). If the modification rate αH of high molecular weight components is less than 50%, the resulting crosslinked material cannot be improved in a balanced manner between wear resistance and rolling resistance. From the viewpoint of obtaining a crosslinked material with a balanced improvement between wear resistance and rolling resistance, the modification rate αH of high molecular weight components is preferably 55% or more, more preferably 60% or more, and even more preferably 65% ​​or more. Furthermore, from the viewpoint of maintaining good processability of the modified conjugated diene polymer (P), the modification rate αH of high molecular weight components is preferably 99% or less, and more preferably 98% or less.

[0057] (Revision Rate of Low Molecular Weight Components) The modified conjugated diene polymer (P) has a revision rate of 50% or more of low molecular weight components (hereinafter also referred to as "revision rate αL of low molecular weight components") of low molecular weight components (Mn) or less, as measured by GPC (i.e., normal GPC measurement). If the revision rate αL of low molecular weight components is less than 50%, the resulting crosslinked material cannot be improved in a balanced manner between wear resistance and rolling resistance. From the viewpoint of obtaining a crosslinked material with a balanced improvement between wear resistance and rolling resistance, the revision rate αL of low molecular weight components is preferably 60% or more, more preferably 65% ​​or more, and even more preferably 70% or more. Furthermore, from the viewpoint of maintaining good processability of the modified conjugated diene polymer (P), the revision rate αL of low molecular weight components is preferably 99% or less, and more preferably 98% or less.

[0058] Regarding the denaturation rate αH of high molecular weight components and the denaturation rate αL of low molecular weight components, the denaturation rate αH of high molecular weight components is the ratio of modified components to the weight-average molecular weight of components in the modified conjugated diene polymer (P) that are equal to or greater than the weight-average molecular weight measured by GPC. The denaturation rate αL of low molecular weight components is the ratio of modified components to the number-average molecular weight of components in the modified conjugated diene polymer (P) that are equal to or less than the number-average molecular weight measured by GPC. In this specification, the denaturation rate αH of high molecular weight components and the denaturation rate αL of low molecular weight components of the modified conjugated diene polymer (P) are values ​​obtained by separating the modified and unmodified components contained in the modified conjugated diene polymer (P) by chromatography and quantifying the unmodified components within a specific molecular weight range. More specifically, these values ​​are calculated using a molecular weight distribution curve based on the polystyrene-converted molecular weight obtained by GPC measurement and a molecular weight distribution curve based on the polystyrene-converted molecular weight obtained by adsorption GPC measurement. Details of the methods for measuring the denaturation rate αH of high molecular weight components and the denaturation rate αL of low molecular weight components are as described in the examples below.

[0059] The denaturation rate αH of high molecular weight components can be adjusted to a desired range by adjusting the type and amount of the starting-end denaturant or the stopping-end denaturant. Starting-end denaturants or stopping-end denaturants having a hydrocarbyl oxysilyl group are preferred because they allow for easy adjustment of the denaturation rate αH of high molecular weight components. Furthermore, the denaturation rate αL of low molecular weight components can be adjusted to a desired range by controlling the timing of the addition of the starting-end denaturant (for example, by adding it in installments).

[0060] (Peak area ratio of molecular weight 400,000 or more) It is preferable that the ratio of the peak area of ​​molecular weight 400,000 or more to the total peak area of ​​the molecular weight distribution curve (GPC curve) obtained by GPC measurement of the modified conjugated diene polymer (P) (hereinafter also referred to as "peak area ratio θs of molecular weight 400,000 or more") is 10% or more. When the peak area ratio θs of molecular weight 400,000 or more is 10% or more, it is possible to further enhance the effect of improving wear resistance while ensuring the rolling resistance of the crosslinked material obtained using the modified conjugated diene polymer (P). From the viewpoint of obtaining a crosslinked material with excellent rolling resistance and wear resistance, the peak area ratio θs of molecular weight 400,000 or more is more preferably 15% or more, more preferably 20% or more, and even more preferably 25% or more. Furthermore, from the viewpoint of ensuring the processability of the modified conjugated diene polymer (P), the peak area ratio θs of molecular weight 400,000 or more is preferably 95% or less, more preferably 90% or less, and even more preferably 85% or less. In this specification, the peak area ratio θs for molecular weights of 400,000 or more is a value calculated based on polystyrene equivalent values ​​obtained by GPC measurement. Details of the measurement method are as described in the examples below.

[0061] <Production of Modified Conjugated Diene Polymer (P)> Next, a method for producing a modified conjugated diene polymer (P) will be described. Any of the polymerization methods used to obtain a modified conjugated diene polymer (P) can be solution polymerization, gas-phase polymerization, or bulk polymerization. Among these polymerization methods, solution polymerization is preferred. In addition, either batch polymerization or continuous polymerization can be used. The following methods are preferred for producing a modified conjugated diene polymer (P): (First method) A monomer containing a conjugated diene compound is polymerized by batch polymerization in the presence of a polymerization initiator, and the polymerization initiator is added to the reactor in multiple portions during polymerization. (Second method) A monomer containing a conjugated diene compound is polymerized by continuous polymerization in the presence of a polymerization initiator.

[0062] When solution polymerization is used in the first and second methods, a specific example of a polymerization method is a method that includes a step of polymerization (hereinafter also referred to as the "polymerization step") in which a monomer containing a conjugated diene compound is polymerized in a solvent (preferably in an organic solvent) in the presence of a polymerization initiator and, if necessary, a vinyl content adjuster (hereinafter also referred to as the "randomizer").

[0063] In the first and second polymerization steps, at least one selected from the group consisting of alkali metal compounds and alkaline earth metal compounds is preferably used as the polymerization initiator. Compounds commonly used as polymerization initiators in the polymerization reaction of conjugated diene compounds can be used as appropriate. The polymerization initiator is preferably a compound formed by the bonding of a hydrocarbon group and an alkali metal element. Examples of such organoalkali metals include methyllithium, ethyllithium, n-propyllithium, n-butyllithium, sec-butyllithium, t-butyllithium, 1,4-dilithiobutane, phenyllithium, stilbenithium, naphthyllithium, 1,3-bis(1-lithio-1,3-dimethylpentyl)benzene, 1,3-phenylenebis(3-methyl-1-phenylpentylidene)dilithium, sodium naphthyl, potassium naphthyl, and the like.

[0064] Of the above, lithium compounds are preferred as polymerization initiators, at least one selected from the group consisting of alkyllithium and aryllithium is more preferred, and alkyllithium (methyllithium, ethyllithium, n-propyllithium, n-butyllithium, sec-butyllithium, t-butyllithium, etc.) is particularly preferred. One polymerization initiator may be used alone, or two or more may be used in combination.

[0065] In the first and second methods, it is preferable to polymerize the monomer in the presence of a compound obtained by mixing a polymerization initiator with compound (M). Compound (MA) can preferably be used as compound (M). In particular, it is preferable to polymerize the monomer in the presence of a compound obtained by mixing compound (MA) with at least one selected from the group consisting of alkali metal compounds and alkaline earth metal compounds (i.e., a metal silane compound).

[0066] Methods for polymerization in the presence of a metal silane compound include the following methods A and B: Method A: A method in which a metal silane compound is produced outside the system by pre-mixing at least one compound selected from the group consisting of alkali metal compounds and alkaline earth metal compounds with compound (MA), and the obtained metal silane compound is mixed with the monomer to carry out polymerization. Method B: A method in which a metal silane compound is produced in the system by mixing compound (MA) with at least one compound selected from the group consisting of alkali metal compounds and alkaline earth metal compounds in a reactor containing the monomer, and then polymerizing the mixture.

[0067] Both Method A and Method B are included in the embodiment of "polymerizing a monomer containing a conjugated diene compound in the presence of a metal silane compound obtained by mixing at least one compound selected from the group consisting of alkali metal compounds and alkaline earth metal compounds with a compound (MA)." From the viewpoint of simplifying the operation, Method B is preferred, while from the viewpoint of sufficiently reducing the rolling resistance of the resulting crosslinked body and improving fuel efficiency, Method A is preferred. Furthermore, Methods A and B may be carried out in combination during polymerization.

[0068] When using Method A as a method for polymerization in the presence of a metal silane compound, the compound (MA) and the polymerization initiator may be mixed in an organic solvent. The organic solvent used to produce the metal silane compound can be any organic solvent that is inert to the compound (MA) and the polymerization initiator. Specifically, examples include aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, etc. In Method A, the temperature when mixing the compound (MA) and the polymerization initiator is preferably -20°C to 150°C, and more preferably 0 to 120°C.

[0069] In the first method, the efficiency of introducing the compound (MA) to the polymerization initiation end can be increased by dividing the polymerization initiator and adding it to the reactor. This makes it possible to sufficiently improve the rolling resistance and wear resistance of the crosslinked material obtained using the modified conjugated diene polymer (P). In the first method, the polymerization initiator and the compound (MA) can be added to the reactor in multiple divided portions, and the specific method is not particularly limited.

[0070] As a specific example of the method for adding the polymerization initiator and compound (MA) in the first method, when polymerization is carried out by method A, the entire amount of compound (MA) and polymerization initiator to be used for polymerization may be mixed in advance, and the mixture of compound (MA) and polymerization initiator may be divided and added to the reactor sequentially. Alternatively, the entire amount of compound (MA) to be used for polymerization and a portion of the polymerization initiator may be mixed in advance, and after mixing this mixture with the monomer to start polymerization, the remaining polymerization initiator may be added to the reactor all at once or in divided portions.

[0071] Furthermore, in the first method, when polymerization is carried out by method B, the entire amount of the compound (MA) to be used for polymerization may be added to the reactor together with the monomer, and after adding a portion of the polymerization initiator to the reactor to start polymerization, the remaining polymerization initiator may be added to the reactor all at once or in portions. When combining methods A and B, first, a portion of the compound (MA) to be used for polymerization may be added to the reactor together with the monomer, and after adding a portion of the polymerization initiator to the reactor to start polymerization, the mixture of the remaining compound (MA) and polymerization initiator may be added to the reactor all at once or in portions. In the second method, the method of adding the metal silane compound to the reactor is not particularly limited, but from the viewpoint of simplifying the operation, it is preferable to continuously add the compound (MA) and the polymerization initiator to the reactor.

[0072] In the first method, the second and subsequent additions of the polymerization initiator may be performed before the polymerization of the monomer begins, or after the polymerization of the monomer has begun. From the viewpoint of increasing the efficiency of introducing the compound (MA) to the polymerization initiation end, it is preferable to perform the second and subsequent additions of the polymerization initiator after the polymerization of the monomer has begun. That is, it is preferable to add the polymerization initiator to the reactor after polymerization has begun with the initial addition of the polymerization initiator. When the polymerization initiator is added in installments, the mass ratio of the amount added in the first installment to the total amount added in the second and subsequent installments is preferably 1:1 to 1:9.

[0073] The amount of compound (MA) used in relation to the polymerization initiator can be appropriately set depending on the type of polymerization initiator. For example, when a lithium compound is used as the metal compound, the amount of compound (MA) used is preferably in the range of 0.2 to 5.0 mol per mol of lithium compound used in polymerization. From the viewpoint of suppressing a decrease in processability when the polymer composition contains a modified conjugated diene polymer (P), the amount of compound (MA) used is more preferably 4.0 mol or less, even more preferably 3.0 mol or less, and even more preferably 1.5 mol or less per mol of lithium compound used in polymerization. Furthermore, from the viewpoint of sufficiently obtaining the effect of reducing rolling resistance, the amount of compound (MA) used is more preferably 0.3 mol or more, even more preferably 0.5 mol or more, and even more preferably 0.9 mol or more per mol of lithium compound used in polymerization.

[0074] In polymerization, the total amount of polymerization initiator used is preferably 0.01 to 20 mmol, and more preferably 0.05 to 15 mmol, per 100 g of monomer used in the synthesis of the modified conjugated diene polymer (P).

[0075] Vinyl content modifiers (randomizers) are used to adjust the vinyl content (the percentage of vinyl groups) in a polymer. Examples of vinyl content modifiers include ether compounds and tertiary amine compounds. Specific examples of vinyl content modifiers include dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, 2,2-di(2-tetrahydrofuryl)propane, 2-(2-ethoxyethoxy)-2-methylpropane, triethylamine, pyridine, N-methylmorpholine, and tetramethylethylenediamine. Vinyl content modifiers can be used individually or in combination of two or more.

[0076] The solvent used for polymerization (hereinafter also referred to as the "polymerization solvent") can be any solvent that is inert to the reaction. Organic solvents are preferably used as polymerization solvents. Examples of organic solvents include linear or cyclic aliphatic hydrocarbons and aromatic hydrocarbons. Among these, hydrocarbons having 3 to 8 carbon atoms are preferred, and specific examples include propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2-butene, cis-2-butene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene, heptane, cyclopentane, methylcyclopentane, methylcyclohexane, 1-pentene, 2-pentene, and cyclohexene. Polymerization solvents can be used individually or in combination of two or more.

[0077] When solution polymerization is carried out, the monomer concentration in the reaction solvent is preferably 5 to 50% by mass, and more preferably 10 to 30% by mass, from the viewpoint of maintaining a balance between productivity and ease of polymerization control. The polymerization reaction temperature is preferably -20°C to 150°C, and more preferably 0 to 120°C. Furthermore, the polymerization reaction is preferably carried out under pressure sufficient to keep the monomer substantially in the liquid phase. By such a polymerization reaction, a conjugated diene polymer having an active end can be obtained. In this specification, "active end" means the part of the polymer chain other than the structure derived from the monomer having a carbon-carbon double bond (more specifically, the metallic end).

[0078] Polymerization can be terminated, for example, by reacting a modified conjugated diene polymer having an active end with an alcohol or hydrogen. Alternatively, a termination end modifier may be reacted with the conjugated diene polymer having an active end. Preferably, the termination end modifier is a compound that has a functional group that covalently bonds to or interacts with the filler and can react with the active end of the polymer. By reacting a conjugated diene polymer having an active end with a termination end modifier, a modified conjugated diene polymer (P) can be obtained in which a functional group that covalently bonds to or interacts with the filler is introduced at the polymerization termination end.

[0079] The terminal modifier is not particularly limited as long as it has a functional group that is covalently bonded to or interacts with the filler (especially silica) and can react with the active end of the conjugated diene polymer. Among these, a compound having one or more atoms selected from the group consisting of nitrogen, sulfur, phosphorus, oxygen, and silicon, and to which no active hydrogen is bonded, can be preferably used as the terminal modifier. In particular, a compound having one or more functional groups selected from the group consisting of an amino group, a group having a carbon-nitrogen double bond, a nitrogen-containing heterocyclic group, a phosphino group, a cyclic ether group, a cyclic thioether group, a protected hydroxyl group, a protected thiol group, and a hydrocarbyloxysilyl group, and that can react with the polymerization active end can be preferably used as the terminal modifier. The amino group is preferably a protected primary amino group, a secondary amino group, or a tertiary amino group. Such compounds are not particularly limited, but for example, one or more compounds described in Japanese Patent Publication No. 2003-171418 and International Publication No. 2021 / 112167 can be suitably used.

[0080] The reaction between a modified conjugated diene polymer having an active end and a termination end modifier 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 complete, or the modified conjugated diene polymer contained in the solution may be isolated and dissolved in a suitable solvent such as cyclohexane before the reaction. The reaction may be carried out using either a batch or continuous method. In this case, the method of adding the termination end modifier is not particularly limited, and examples include adding it all at once, adding it in portions, or adding it continuously.

[0081] The amount of the terminating terminal modifier to be used may be appropriately set according to the type of the compound used in the reaction. The amount of the terminating terminal modifier is preferably 0.1 molar equivalent or more, more preferably 0.3 mol to 1.5 equivalents, relative to the metal element involved in the polymerization reaction of the polymerization initiator. The reaction temperature is usually the same as the temperature of the polymerization reaction, is preferably -20 to 150°C, and more preferably 0 to 120°C. When the temperature of the modification reaction is low, the viscosity of the polymer solution tends to increase. Further, when the temperature of the modification reaction is high, the polymerization active terminals are prone to deactivation. The reaction time is preferably 1 minute to 5 hours, more preferably 2 minutes to 1 hour.

[0082] The modified conjugated diene-based polymer (P) may be obtained by further reacting the conjugated diene-based polymer obtained by the above polymerization step or modification step with an onium salt-forming agent. In this case, as the modified conjugated diene-based polymer (P), a polymer having an onium salt structure at a polymer terminal can be obtained. It is preferable that the modified conjugated diene-based polymer (P) has an onium salt structure because the shape retention of a crosslinked product obtained using the modified conjugated diene-based polymer (P) can be improved. As the onium salt-forming agent, onium salt-forming agents generally used in producing onium-modified conjugated diene-based polymers can be appropriately used.

[0083] Isolation of the modified conjugated diene-based polymer (P) contained in the reaction solution can be performed by a known desolvation method such as steam stripping and a drying operation such as heat treatment.

[0084] <<Polymer Composition>> The polymer composition of the present disclosure contains the above modified conjugated diene-based polymer (P) and a filler. Unless otherwise specified, each component contained in the polymer composition may be used alone or in combination of two or more.

[0085] [B] Filler As the filler, at least one selected from the group consisting of silica, carbon black, and a compound represented by the following formula (2) can be preferably used. nM １ ·mSiO ｋ ·iH ２ O ... (2) (In formula (2), M１ (This refers to at least one selected from the group consisting of aluminum, magnesium, titanium, zirconium, and calcium (hereinafter also referred to as "specific metals"), oxides of specific metals, hydroxides of specific metals, and carbonates of specific metals. n is an integer from 1 to 5, m is an integer from 0 to 10, k is an integer from 2 to 5, and i is an integer from 0 to 10.)

[0086] [B1] Silica There are no particular restrictions on the silica, and examples include wet silica (hydrated silica), dry silica (anhydrous silica), calcium silicate, aluminum silicate, silica derived from rice husks, silica derived from rice bran, etc. Among these, wet silica is preferred.

[0087] The BET specific surface area of ​​silica (a value measured in accordance with ISO 5794 / 1) is 40 to 350 m². ２ A range of 80 to 300 m is preferred. ２ A range of 120 to 250 m / g is more preferable. ２ A range of / g is particularly preferred. Silica with a BET specific surface area in this range has the advantage of being able to achieve both dispersibility in modified conjugated diene polymers (P) and rubber reinforcing properties. An example of such silica is "Nipsil AQ" manufactured by Tosoh Silica Co., Ltd. (BET specific surface area = 205 m²). ２ / g), "Nipsil KQ", manufactured by Degussa, product name "Ultrazil VN3" (BET specific surface area = 175 m²) ２ Commercially available products such as ( / g) can be used.

[0088] The amount of silica added is preferably in the range of 20 to 160 parts by mass, and more preferably in the range of 30 to 150 parts by mass, per 100 parts by mass of the rubber component containing the modified conjugated diene polymer (P). If the amount of silica added is 20 parts by mass or more per 100 parts by mass of the rubber component, the rolling resistance, fracture properties, and abrasion resistance of the crosslinked body obtained from the polymer composition can be sufficiently improved. Furthermore, if the amount of silica added is 160 parts by mass or less, the processability of the polymer composition can be sufficiently improved.

[0089] In this specification, the term "rubber component" in a polymer composition refers to a polymer from which a cured product exhibiting rubber elasticity can be obtained upon curing. This cured product exhibits the property of undergoing large deformation with a small force at room temperature (for example, deformation that causes it to stretch to more than twice its original size when stretched at room temperature), and rapidly returning to almost its original shape when the force is removed.

[0090] [B2] Carbon Black The polymer composition of this disclosure preferably contains carbon black as a filler, from the viewpoint of fracture characteristics and wear resistance of the crosslinked material obtained from the polymer composition. The carbon black is not particularly limited, and examples include GPF, FEF, HAF, ISAF, and SAF grade carbon black.

[0091] Nitrogen adsorption specific surface area of ​​carbon black (N ２ SA) is not particularly limited. For reasons such as being superior in obtaining the effects of this disclosure, the specific surface area of ​​nitrogen adsorption of carbon black (N) ２ SA) is 50-200m ２ / g is preferred, and 70 to 150m ２ / g is more preferable. Note that the nitrogen adsorption specific surface area (N ２ SA) is the value obtained by measuring the amount of nitrogen adsorbed onto the carbon black surface according to JIS K6217-2:2001 "Part 2: Method for determining specific surface area - Nitrogen adsorption method - Single point method".

[0092] If the polymer composition of this disclosure contains carbon black, the carbon black content in the polymer composition is preferably in the range of 1 to 150 parts by mass, and more preferably in the range of 3 to 120 parts by mass, per 100 parts by mass of the rubber component containing the modified conjugated diene polymer (P).

[0093] [B3] Compounds represented by formula (2) Specific examples of compounds represented by formula (2) include alumina (Al) such as γ-alumina and α-alumina. ２ O ３ Alumina monohydrate (Al) such as boehmite and diaspore. ２ O ３ ・H ２ O), aluminum hydroxide [Al(OH) ] such as gibbsite and bayerite ３], aluminum carbonate [Al ２ (CO ３ ) ３ ], magnesium hydroxide [Mg(OH) ２ ], magnesium oxide (MgO), magnesium carbonate (MgCO2) ３ ), talc (3MgO・4SiO ２ ・H ２ O), attapulgite (5MgO・8SiO ２ 9H ２ O), Titanium White (TiO ２ ), Titanium Black (TiO ２ｎ－１ ), calcium oxide (CaO), calcium hydroxide [Ca(OH) ２ ], magnesium aluminum oxide (MgO・Al ２ O ３ ), clay (Al ２ O ３ ・2SiO ２ ), kaolin (Al ２ O ３ ・2SiO ２ ・2H ２ O), pyrophyllite (Al ２ O ３ 4SiO ２ ・H ２ O), Bentonite (Al ２ O ３ 4SiO ２ ・2H ２ O), aluminum silicate (Al ２ SiO ５ Al ４ 3SiO ４ ・5H ２ O, etc.), magnesium silicate (Mg ２ SiO ４ MgSiO ３ (etc.), calcium silicate (Ca ２ SiO ４ (e.g.), aluminum calcium silicate (Al ２ O ３ CaO・2SiO ２ (etc.), magnesium calcium silicate (CaMgSiO) ４ ), calcium carbonate (CaCO3) ３ ), zirconium oxide (ZrO ２), zirconium hydroxide [ZrO(OH) ２ nH ２ O], Zirconium carbonate [Zr(CO) ３ ) ２ Examples include:

[0094] In the polymer composition of this disclosure, the filler content is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, per 100 parts by mass of the rubber component contained in the polymer composition. Furthermore, the filler content is preferably 160 parts by mass or less, more preferably 120 parts by mass or less. When the filler content in the polymer composition is within the above range, applying the polymer composition to the tire tread makes it possible to achieve an even higher level of balance between the tire's rolling resistance, braking performance on wet roads, handling performance on dry roads, and wear resistance.

[0095] The polymer composition of this disclosure may further contain, in addition to the modified conjugated diene polymer (P) and fillers, the various components listed below.

[0096] [C] Other Rubber Components The polymer composition of this disclosure preferably further includes, as a rubber component other than the modified conjugated diene polymer (P), at least one selected from the group consisting of natural rubber, isoprene rubber, butadiene rubber, emulsion polymerized styrene-butadiene rubber, solution polymerized styrene-butadiene rubber, hydrogenated butadiene rubber, hydrogenated styrene-butadiene rubber, butyl rubber, halogenated butyl rubber, ethylene-propylene rubber, and ethylene-butadiene rubber. Among these, it is preferable to include one or more of natural rubber, butadiene rubber, and styrene-butadiene rubber. When mixing the other rubber components with the modified conjugated diene polymer (P), for example, the mixing of the other rubber components with the modified conjugated diene polymer (P) is carried out during the kneading process using a Banbury mixer, rolls, etc., which is normally performed.

[0097] The ratio of the modified conjugated diene polymer (P) to other rubber components is preferably such that the modified conjugated diene polymer (P) is 5 to 95 parts by mass per 100 parts by mass of the total of the modified conjugated diene polymer (P) and other rubber components. More preferably, the ratio of the modified conjugated diene polymer (P) to other rubber components is such that the modified conjugated diene polymer (P) is 20 to 90 parts by mass per 100 parts by mass of the total of the modified conjugated diene polymer (P) and other rubber components. In particular, when the modified conjugated diene polymer (P) and other rubber components are blended such that the modified conjugated diene polymer (P) is 35 to 85 parts by mass per 100 parts by mass of the total of the modified conjugated diene polymer (P) and other rubber components, the resulting polymer composition is suitable as a polymer composition for manufacturing tire rubber.

[0098] [D] Resin The polymer composition of the present disclosure may contain a thermoplastic or thermosetting resin (hereinafter also simply referred to as "resin (D)"). From the viewpoint of obtaining a crosslinked material with excellent properties in terms of strength, abrasion resistance and crack growth resistance, resin (D) is preferably at least one selected from the group consisting of styrene resins, α-methylstyrene resins, polyethylene, C5 resins, hydrogenated C5 resins, C9 resins, hydrogenated C9 resins, C5 / C9 resins, hydrogenated C5 / C9 resins, dicyclopentadiene resins, hydrogenated dicyclopentadiene resins, dicyclopentadiene-C9 resins, hydrogenated dicyclopentadiene-C9 resins, alkylphenol resins, coumarone indene resins, terpene resins, and hydrogenated terpene resins. Resin (D) is more preferably at least one selected from the group consisting of C5 resins, hydrogenated C5 resins, C9 resins, hydrogenated C9 resins, C5 / C9 resins, hydrogenated C5 / C9 resins, dicyclopentadiene resins, hydrogenated dicyclopentadiene resins, dicyclopentadiene-C9 resins, hydrogenated dicyclopentadiene-C9 resins, terpene resins, and hydrogenated terpene resins.

[0099] The resin (D) is preferably a thermoplastic resin. If the resin (D) is a thermoplastic resin, the softening point of the resin (D) is preferably 60°C or higher, and more preferably 70°C or higher. Furthermore, the softening point of the resin (D) is preferably 180°C or lower, and more preferably 170°C or lower.

[0100] When resin (D) is blended into the polymer composition, the amount of resin (D) blended is preferably 1 part by mass or more per 100 parts by mass of rubber components contained in the polymer composition. [F] Blending 1 part by mass or more of resin is preferable because it allows for sufficiently high improvement in abrasion resistance, tensile strength, and crack growth resistance in the crosslinked body obtained using the polymer composition due to the addition of resin (D). When resin (D) is blended into the polymer composition, the blending ratio of resin (D) is more preferably 5 parts by mass or more per 100 parts by mass of rubber components, and even more preferably 10 parts by mass or more. Furthermore, from the viewpoint of maintaining the various properties of the rubber composition well, the blending ratio of resin (D) is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 50 parts by mass or less per 100 parts by mass of rubber components contained in the polymer composition.

[0101] [E] Silane Coupling Agents By incorporating a silane coupling agent into the polymer composition of this disclosure, the dispersibility of silica can be further enhanced. The silane coupling agent is not particularly limited, but sulfur-containing silane coupling agents are preferred. Examples of sulfur-containing silane coupling agents include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, 3-trimethoxysilylpropylbenzothiazoletetrasulfide, γ-mercaptopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-[ethoxybis(3,6,9,12,15-pentaoxacosan-1-yloxy)silyl]propane-1-thiol (e.g., Evonik Corporation, trade name "Si363"), and mercapto-silane compounds such as NXT and NXT-Z manufactured by Momentive.

[0102] When a silane coupling agent is incorporated into a polymer composition, the content of the silane coupling agent is preferably 1 to 20 parts by mass per 100 parts by mass of silica. By having a silane coupling agent content of 1 part by mass or more, a sufficient improvement in the dispersibility of silica can be obtained. Furthermore, by having a silane coupling agent content of 20 parts by mass or less, a decrease in processability and elongation at break can be suppressed. More preferably, the content of the silane coupling agent is 5 to 15 parts by mass per 100 parts by mass of silica.

[0103] [F] Crosslinking Agent The polymer composition of this disclosure may contain a crosslinking agent. By containing a crosslinking agent in the polymer composition of this disclosure, a crosslinked body with improved strength and abrasion resistance can be obtained. Examples of crosslinking agents include sulfur, sulfur halides, organic peroxides, quinone dioximes, organic polyvalent amine compounds, alkylphenol resins having methylol groups, etc., and sulfur is usually used. When a crosslinking agent is incorporated into the polymer composition, the amount of the crosslinking agent is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, based on 100 parts by mass of the total amount of rubber components contained in the polymer composition.

[0104] [G] Process oil The polymer composition may contain process oils commonly used for oil-laying elastomers as oils for oil-laying. Process oils are incorporated into the polymer composition, for example, by directly adding the oil to the rubber compound. Preferred process oils include a variety of oils known in the industry, such as aromatic oils, paraffinic oils, naphthenic oils, vegetable oils such as soybean oil and sunflower oil, and oils with a low content of polycyclic aromatic compounds (low PCA oils), such as mild extraction solvates (MES), treated distillate aromatic extracts (TDAEs), special residual aromatic extracts (SRAEs) from residual oils, and heavy naphthenic oils. Examples of commercially available MES, TDAE, and SRAE include Shell's Catenex SNR (heavy paraffin obtained by dewaxing distillate oil with a solvent) as an MES, H&R Wasag AG's Vivatec 500 as a TDAE, and Japan Energy Corp.'s NC140 as an SRAE. When process oil is blended into the polymer composition, the amount of process oil is preferably 10 to 100 parts by mass per 100 parts by mass of the total amount of rubber components contained in the polymer composition.

[0105] In addition to the components described above, the polymer composition may contain various additives commonly used in polymer compositions for manufacturing tire rubber, such as antioxidants, zinc oxide, stearic acid, softeners, vulcanization accelerators, compatibilizers, vulcanization aids, processing aids, and scorch inhibitors. The amounts of these additives can be appropriately selected depending on the components, as long as they do not impair the effects of the disclosed material.

[0106] The polymer composition of this disclosure can be applied to various rubber products as a crosslinked body by mixing polymer components, fillers, and other components as needed using a mixer such as an open-type mixer (e.g., a roll mixer) or a closed-type mixer (e.g., a Banbury mixer), and then crosslinking (vulcanizing) after molding. Specifically, the crosslinked body of this disclosure can be applied to tire applications such as tire treads, undertreads, carcasses, sidewalls, and bead sections; sealing materials such as packings, gaskets, weatherstrips, and O-rings; interior and exterior surface materials for various vehicles such as automobiles, ships, aircraft, and railways; building materials; vibration-damping rubber for industrial machinery and equipment; various hoses and hose covers such as diaphragms, rolls, radiator hoses, and air hoses; belts such as power transmission belts; linings; dust boots; medical equipment materials; fenders; insulating materials for electric wires; and other industrial products.

[0107] Modified conjugated diene polymers (P) can be used to obtain crosslinked materials with good physical properties required for tire applications, such as rolling resistance (low fuel consumption) and wear resistance. Therefore, polymer compositions containing modified conjugated diene polymers (P) are particularly suitable as materials for tire treads, sidewalls, or both.

[0108] Tires can be manufactured according to conventional methods. For example, a polymer composition can be mixed in a kneader to form a sheet, which can then be placed in a predetermined position (for example, outside the carcass in the case of a sidewall) according to conventional methods and vulcanized to form tread rubber or sidewall rubber, thereby obtaining a pneumatic tire.

[0109] According to the above detailed disclosure, the following means are provided: [1] A modified conjugated diene polymer having a weight-average molecular weight (Mw) of 10 × 10 as measured by gel permeation chromatography (GPC) ４ The above 200 x 10 ４A modified conjugated diene polymer having the following characteristics, wherein the molecular weight distribution (Mw / Mn), expressed as the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn), is 1.40 or more and 4.00 or less, the modification rate with respect to the total amount of the modified conjugated diene polymer is 80% or more, the modification rate of the high molecular weight component of the modified conjugated diene polymer that is equal to or greater than the weight-average molecular weight measured by GPC is 50% or more, and the modification rate of the low molecular weight component of the modified conjugated diene polymer that is equal to or less than the number-average molecular weight measured by GPC is 50% or more. [2] The modified conjugated diene polymer according to [1], wherein the ratio of the peak area of ​​a molecular weight of 400,000 or more to the total peak area of ​​the molecular weight distribution curve obtained by GPC measurement is 10% or more. [3] The modified conjugated diene polymer according to [1] or [2], wherein the Mooney viscosity measured at 100°C is 20 to 150. [4] The modified conjugated diene polymer according to any one of [1] to [3], which is linear. [5] A modified conjugated diene polymer according to any one of [1] to [4], wherein the silicon content is 70 ppm or more. [6] A modified conjugated diene polymer according to any one of [1] to [5], wherein the nitrogen content is 70 ppm or more. [7] A modified conjugated diene polymer according to any one of [1] to [6], comprising a molecule having a substructure derived from a compound (M) having a silicon atom at at least one end of the polymer chain. [8] A modified conjugated diene polymer according to [7], wherein the compound (M) further comprises a nitrogen atom. [9] A modified conjugated diene polymer according to [7] or [8], wherein the compound (M) is represented by the above formula (1).

[10] A polymer composition comprising a modified conjugated diene polymer according to any one of [1] to [9] and a filler.

[11] The polymer composition according to

[10] , further comprising at least one rubber component selected from the group consisting of natural rubber, isoprene rubber, butadiene rubber, emulsion polymerized styrene-butadiene rubber, solution polymerized styrene-butadiene rubber, hydrogenated butadiene rubber, hydrogenated styrene-butadiene rubber, butyl rubber, halogenated butyl rubber, ethylene-propylene rubber, and ethylene-butadiene rubber, which is different from the modified conjugated diene polymer.

[12] A crosslinked body obtained by crosslinking the polymer composition according to

[10] or

[11] .

[13] A tire having a tread, a sidewall, or both formed using the polymer composition described in

[10] or

[11] .

[0110] The present invention will be described in detail below based on examples, but it is not limited to the following examples. In the following synthesis examples, examples, and comparative examples, "parts" and "%" refer to mass unless otherwise specified. The methods for measuring various physical properties of the polymer are shown below.

[0111] - Bound styrene content (%) and vinyl content (mol%): Using deuterated chloroform as the solvent, at 400 MHz １ It was calculated by 1H-NMR measurement.

[0112] - Weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the polymer: These were determined using a gel permeation chromatograph (normally GPC measurement) equipped with a polystyrene column to obtain a chart (GPC curve) based on the molecular weight converted to polystyrene, and then calculated based on that chart. The specific GPC measurement conditions are as follows: (GPC measurement conditions) Measuring instrument: HLC-8020 (Tosoh Corporation) Column: Two GMH-HR-H columns (Tosoh Corporation) connected in series Detector: Differential refractometer RI-8020 (Tosoh Corporation) Eluent: Tetrahydrofuran column Temperature: 40°C Flow rate: 1.0 mL / min Sample concentration: 10 mg / 20 mL

[0113] - The ratio of the peak area of ​​molecular weights above 400,000 to the total peak area of ​​the GPC curve, θs, was calculated from the GPC curve based on the molecular weight in polystyrene terms using the following formula (1). In formula (1), APs represents the total area of ​​the peaks corresponding to the measured sample (conjugated diene polymer) in the GPC curve obtained by normal GPC measurement. θs = ((Peak area of ​​molecular weights above 400,000) / APs) × 100 …(1)

[0114] - Modification rate αT relative to the total amount of modified conjugated diene polymer: A gel permeation chromatograph (adsorption GPC measurement) was used with a silica column connected in series upstream and a polystyrene column connected downstream to obtain a chart (adsorption GPC curve) based on the molecular weight in polystyrene terms. Based on this chart, the modification rate αT (unit: %) was calculated using the following formula (2): αT = (1 - ((APa / APs) × (ASs / ASA))) × 100 …(2) In formula (2), APs, APa, ASs, and ASA are as follows (see Figure 1). APs: Total area of ​​peaks corresponding to the measured sample (conjugated diene polymer) in the GPC curve obtained by conventional GPC measurement. APa: Total area of ​​peaks corresponding to the measured sample (conjugated diene polymer) in the GPC curve obtained by adsorption GPC measurement. ASs: Total area of ​​peaks corresponding to the internal standard polystyrene in the GPC curve obtained by conventional GPC measurement. ASa: Total area of ​​peaks corresponding to the internal standard polystyrene in the GPC curve obtained by adsorption GPC measurement.

[0115] The specific measurement conditions for adsorption GPC are as follows: (Adsorption GPC Measurement Conditions) Measuring instrument: LC-20A (Shimadzu Corporation) Column: Two silica-based columns "ZORBAX PSM 60-S" (Agilent) and two polystyrene-based columns "TSKgel GMHXL" (Tosoh Corporation) were used in series. Detector: RID-20A (Shimadzu Corporation) Eluent: Tetrahydrofuran Column temperature: 40°C Flow rate: 0.4 mL / min Sample concentration: 10 mg / 20 mL

[0116] - Modification rate αH of high molecular weight components and modification rate αL of low molecular weight components in conjugated diene polymers: Standard polystyrene was measured using both conventional GPC measurement and adsorption GPC measurement, and calibration curves were created for each. In addition, conventional GPC measurement and adsorption GPC measurement were performed on the measurement sample (conjugated diene polymer), and GPC curves were obtained for each. Using the two obtained GPC curves, the modification rates αH and αL were determined by the following procedure. In the GPC curve obtained by conventional GPC measurement, among the peak areas corresponding to the measurement sample (conjugated diene polymer), the peak area greater than or equal to the weight-average molecular weight (Mw) obtained by conventional GPC measurement was defined as APsMw, and the peak area less than or equal to the number-average molecular weight (Mn) obtained by conventional GPC measurement was defined as APsMn. Furthermore, in the chart obtained by adsorption GPC measurement (adsorption GPC curve), the adsorption GPC curve is divided at the elution time t1 on the adsorption GPC curve corresponding to the weight-average molecular weight (Mw) obtained by normal GPC measurement, and the peak area with an elution time of t1 or less is defined as APaMw. In addition, in the adsorption GPC curve, the adsorption GPC curve is divided at the elution time t2 on the adsorption GPC curve corresponding to the number-average molecular weight (Mn) obtained by normal GPC measurement, and the peak area with an elution time of t2 or more is defined as APaMn (see Figure 2). The denaturation rate αH (unit: %) of the high molecular weight component was calculated using the following formula (3), and the denaturation rate αL (unit: %) of the low molecular weight component was calculated using the following formula (4). In formulas (3) and (4), ASs and ASa are the same as in formula (2) above. αH=(1-((APaMw / APsMw)×(ASs / ASa)))×100…(3) αL=(1-((APaMn / APsMn)×(ASs / ASa)))×100…(4)

[0117] - Nitrogen content of polymers (ppm): Measured using a trace total nitrogen analyzer in accordance with the "chemiluminescence method" in JIS K-2609:1998 "Crude oil and petroleum products - Nitrogen content test method". The measurement method involved thermal decomposition of the sample under argon gas flow, followed by combustion oxidation with oxygen gas. The resulting nitric oxide was then oxidized with ozone gas under dehydration conditions. The emission intensity detected at 590–2500 nm was measured, and the nitrogen content was determined from the area value of the emission intensity. (Trace total nitrogen analyzer measurement conditions) Measuring instrument: TN-2100H (manufactured by Mitsubishi Chemical Analytec Co., Ltd.)

[0118] - Silicon content of polymers (ppm): The silicon content of modified conjugated diene polymers was measured using an ICP mass spectrometer (Agilent 7700s, Agilent Technologies).

[0119] • Mooney viscosity of polymers (ML) １＋４ (100°C): Determined in accordance with JIS K6300-1:2013, using an L rotor, under the conditions of preheating for 1 minute, rotor operating time for 4 minutes, and temperature of 100°C.

[0120] 1. Production of Modified Conjugated Diene Polymers <Example 1> In a nitrogen-purged autoclave reactor with a volume of 5 liters, 2250 g of cyclohexane, 9.8 mL of tetrahydrofuran as a vinyl content adjuster (randomizer), 2.16 mmol of 1-(3-(dimethyl(tert-amyloxy)silyl)propyl)piperazine as an initiating terminal modifier, and 50 g of styrene and 450 g of 1,3-butadiene as monomers were charged. After adjusting the temperature of the reactor contents to 28°C, 3.61 mmol of n-butyllithium was added as a polymerization initiator to start polymerization. After 10, 15, 20, and 30 minutes from the start of polymerization, lithium 4-(3-(dimethyl(tert-amyloxy)silyl)propyl)piperazine-1-ide was divided into four equal parts and added in each addition to a total of 2.40 mmol. Polymerization was carried out under adiabatic conditions, and the maximum temperature reached 88°C. After the polymerization conversion rate reached 99% (37 minutes after the start of polymerization), 5 mL of methanol was added as a polymerization inhibitor. 4.40 g of 2,6-di-tert-butyl-p-cresol was added to the resulting polymer solution. Then, the solvent was removed by steam stripping, and the solution was dried using a heated roller at 110°C to obtain the modified conjugated diene polymer A-1.

[0121] <Example 2> In a nitrogen-purged autoclave reactor with a volume of 5 liters, 2800 g of cyclohexane, 13.2 mL of tetrahydrofuran as a vinyl content adjuster (randomizer), 1.92 mmol of 1-(3-(dimethyl(tert-amyloxy)silyl)propyl)piperazine as an initiating terminal modifier, and 40 g of styrene and 360 g of 1,3-butadiene as monomers were charged. After adjusting the temperature of the reactor contents to 60°C, 2.75 mmol of n-butyllithium was added as a polymerization initiator to start polymerization. After 10, 15, 20, and 30 minutes from the start of polymerization, lithium 4-(3-(dimethyl(tert-amyloxy)silyl)propyl)piperazine-1-ide was added in equal amounts in four parts to a total of 1.92 mmol. Polymerization was carried out under isothermal conditions and the temperature was adjusted to a constant 60°C. After the polymerization conversion rate reached 99% (60 minutes after the start of polymerization), 5 mL of methanol was added as a polymerization inhibitor. 3.52 g of 2,6-di-tert-butyl-p-cresol was added to the resulting polymer solution. Then, the solvent was removed by steam stripping, and the solution was dried using a heated roller at 110°C to obtain the modified conjugated diene polymer A-2.

[0122] <Example 3> Polymerization was carried out in the same manner as in Example 1, except that the amount of reagents used was as shown in Table 1. Modified conjugated diene polymer A-3 was obtained by desolvation and drying.

[0123] <Example 4> In a nitrogen-purged autoclave reactor with a volume of 5 liters, 2250 g of cyclohexane, 2.45 mL of tetrahydrofuran as a vinyl content adjuster (randomizer), 3.09 mmol of 1-(3-(dimethyl(tert-amyloxy)silyl)propyl)piperazine as an initiating terminal modifier, and 100 g of styrene and 400 g of 1,3-butadiene as monomers were charged. After adjusting the temperature of the reactor contents to 28°C, 3.61 mmol of n-butyllithium was added as a polymerization initiator to start polymerization. After 10, 15, 20, and 30 minutes from the start of polymerization, n-butyllithium was divided into four equal parts and added each time to a total of 1.20 mmol. Polymerization was carried out under adiabatic conditions, and the maximum temperature reached 88°C. After the polymerization conversion rate reached 99% (50 minutes after the start of polymerization), 1.08 mmol of 3-(bistrimethylsilyl)aminopropylmethyldiethoxysilane (mod-1) was added as a termination-end modifier. 4.40 g of 2,6-di-tert-butyl-p-cresol was added to the resulting polymer solution. The solvent was then removed by steam stripping, and the solution was dried using a heated roller at 110°C to obtain the modified conjugated diene polymer A-4.

[0124] <Comparative Example 1> In a nitrogen-purged autoclave reactor with a volume of 5 liters, 2250 g of cyclohexane, 9.8 mL of tetrahydrofuran as a vinyl content adjuster (randomizer), and 50 g of styrene and 450 g of 1,3-butadiene were charged. After adjusting the temperature of the reactor contents to 28°C, 3.61 mmol of n-butyllithium was added as a polymerization initiator to start polymerization. After the polymerization conversion rate reached 99% (30 minutes after the start of polymerization), 3.2 mmol of mod-1 was added as a termination-end modifier. 4.40 g of 2,6-di-tert-butyl-p-cresol was added to the obtained polymer solution. Then, the solvent was removed by steam stripping, and the modified conjugated diene polymer B-1 was obtained by drying with a hot roll heated to 110°C.

[0125] <Comparative Example 2> Polymerization was carried out in the same manner as in Comparative Example 1, except that the amount of reagents used was as shown in Table 1. Modified conjugated diene polymer B-2 was obtained by desolvation and drying.

[0126] <Comparative Example 3> Polymerization was carried out in the same manner as in Comparative Example 1, except that the amount of reagents used was as shown in Table 1. Modified conjugated diene polymer B-3 was obtained by desolvation and drying.

[0127]

[0128] In Table 1, INA-1, INB-1, mod-1, and mod-2 represent the following compounds: INA-1: 1-(3-(dimethyl(tert-amyloxy)silyl)propyl)piperazine INB-1: Lithium 4-(3-(dimethyl(tert-amyloxy)silyl)propyl)piperazine-1-id

[0129] <Example 5> Three 21-liter autoclave reactors with nitrogen purging were connected in series. The first reactor was continuously charged at a rate of 0.851 mmol / min with 88.9 g / min of 1,3-butadiene as monomer, 22.2 g / min of styrene, 770.9 g / min of cyclohexane as solvent, 2.75 g / min of tetrahydrofuran as a vinyl group content adjuster (randomizer), and a mixture (1 / 1 molar ratio) of n-butyllithium as a polymerization initiator and 1-(3-(dimethyl(tert-amyloxy)silyl)propyl)piperazine as an initiating end modifier, while the reactor temperature was controlled at 75°C. The polymer solution was continuously discharged from the first reactor at a rate of 878.2 g / min, and the discharged polymer solution was continuously introduced into the second reactor to carry out the reaction. The polymer solution was continuously discharged from the second reactor at a rate of 878.2 g / min, and the discharged polymer solution was continuously introduced into the third reactor to continue the reaction. At the outlet of the third reactor, di-tert-butyl-p-cresol was added at a ratio of 1.36 parts by mass per 100 parts by mass of polymer. The resulting polymer solution was desolvated by steam stripping and dried using a heated roller at 110°C to obtain the modified conjugated diene polymer A-5.

[0130] <Example 6> Modified conjugated diene polymer A-6 was obtained by polymerization, solvent removal, and drying in the same manner as in Example 5, except that the amount of reagents used was as shown in Table 2.

[0131] <Example 7> Modified conjugated diene polymer A-7 was obtained by polymerization, desolvation, and drying in the same manner as in Example 5, except that the amounts of reagents used were as shown in Table 2, and lithium 4-(3-(dimethyl(tert-amyloxy)silyl)propyl)piperazine-1-id was added at a rate of 0.639 mmol / min at the inlet of the second reactor.

[0132] <Example 8> Modified conjugated diene polymer A-8 was obtained by polymerization, desolvation, and drying in the same manner as in Example 5, except that the amount of reagents used was as shown in Table 2, and mod-1 was added at a rate of 0.63 mmol / min at the outlet of the second reactor.

[0133] <Example 9> Modified conjugated diene polymer A-9 was obtained by polymerization, desolvation, and drying in the same manner as in Example 5, except that the amount of reagents used was as shown in Table 2, and ethanol was added at a rate of 0.63 mmol / min at the outlet of the second reactor.

[0134] <Example 10> The amount of reagents used was as shown in Table 2, and a 1 / 1 mixture (molar ratio) of bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-ather-2-silacyclopentane)]amine (referred to as mod-3) and dichlorodimethylsilane was added at a rate of 0.321 mmol / min at the outlet of the second reactor. Except for this, polymerization, desolvation, and drying were carried out in the same manner as in Example 5 to obtain a modified conjugated diene polymer A-10.

[0135] <Comparative Example 4> Modified conjugated diene polymer B-4 was obtained by polymerization, desolvation, and drying in the same manner as in Example 5, except that the amount of reagents used was as shown in Table 2, and mod-3 was added at 0.159 mmol / min at the outlet of the second reactor.

[0136] <Comparative Example 5> A nitrogen-purged autoclave reactor with an internal volume of 21 liters (first reactor) was continuously charged at a rate of 88.9 g / min of 1,3-butadiene as monomer, 22.2 g / min of styrene, 770.9 g / min of cyclohexane as solvent, 2.75 g / min of tetrahydrofuran as vinyl group content adjuster (randomizer), 0.851 mmol / min of n-butyllithium as polymerization initiator, and 2.55 mmol / min of 4-dimethylaminostyrene as starting end modifier, while the temperature inside the reactor was controlled at 75°C. The polymer solution was continuously discharged from the first reactor at a rate of 878.2 g / min, and the discharged polymer solution was continuously introduced into the second reactor to carry out the reaction. At the outlet of the second reactor, 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1-amine) (referred to as mod-4) was added at a rate of 0.159 mmol / min. Subsequently, at the outlet of the third reactor, di-tert-butyl-p-cresol was added at a rate of 1.36 parts by mass per 100 parts by mass of polymer. The resulting polymer solution was desolvated by steam stripping and dried using a heated roller at 110°C to obtain the modified conjugated diene polymer B-5.

[0137] <Comparative Example 6> Modified conjugated diene polymer B-6 was obtained by polymerization, desolvation, and drying in the same manner as in Example 5, except that the amount of reagents used was as shown in Table 2, and mod-2 was added at a rate of 0.257 mmol / min at the outlet of the second reactor.

[0138]

[0139] In Table 2, mod-3 and mod-4 represent the following compounds. (mod-1 and mod-2 are the same as in Table 1.)

[0140] 2. Production of Polymer Compositions and Crosslinked Products <Comparative Examples 1-6, Examples 1-10> Polymer compositions were produced by blending each component according to the formulations shown in Tables 3 and 4 and then melt-kneading them. The kneading was carried out by the following method. Using a batch mixer equipped with a temperature control device (manufactured by Toyo Seiki Seisakusho Co., Ltd.; product name Laboplastmill), for the first stage of kneading, the temperature was set to 100°C, the rotation speed was 60 rpm, and the kneading time was 4 minutes, during which the modified conjugated diene polymer, polybutadiene rubber (BR), draw oil, silica, carbon black, silane coupling agent, stearic acid, antioxidant, and zinc oxide were blended and kneaded. Next, for the second stage of kneading, after the kneaded product obtained in the first stage of kneading was cooled to room temperature, a vulcanization accelerator and sulfur were added to the above mixer, the temperature was set to 70°C, and the kneading was carried out at a rotation speed of 60 rpm and a kneading time of 1.5 minutes to obtain the formulation. The temperature of the kneaded material discharged from the mixer was 100°C or lower in all cases. Next, each of the obtained formulations was vulcanized and molded in a vulcanizing press at 160°C for a predetermined time to obtain vulcanized rubber (crosslinked material). The following physical properties were evaluated using the obtained vulcanized rubber. The results are shown in Tables 3 and 4.

[0141] [Method for Evaluating Compound Properties] ・Rolling resistance (3% tanδ @ 50°C) Vulcanized rubber was used as the measurement sample, and a shear-type dynamic spectrometer (manufactured by TA Instruments) was used to measure the ratio of the loss modulus G'' to the storage modulus G' (50°C tanδ) under conditions of an angular velocity of 100 radians per second, a temperature of 50°C, and a shear strain of 3%. The results are shown as an index with Comparative Example 1 set to 100, and a larger value indicates lower rolling resistance, better rolling resistance, and better fuel efficiency.

[0142] - Abrasion resistance (DIN abrasion): Vulcanized rubber was used as the measurement sample, and the abrasion was measured using a DIN abrasion tester (manufactured by Toyo Seiki Co., Ltd.) in accordance with JIS K6264, under a load of 10 N at 25°C. The measurement results are shown as an index with Comparative Example 1 set to 100. A higher value indicates better abrasion resistance.

[0143]

[0144]

[0145] The details of each component in Tables 3 and 4 are as follows: *1) ENEOS Material Co., Ltd., product name "BR01" *2) Solvay Corporation, product name "ZEOSIL 1165MP" *3) Mitsubishi Chemical Corporation, product name "Diablack N330" *4) Evonik Corporation, product name "Si75" *5) ENEOS Corporation, process oil product name "T-DAE" *6) Seiko Chemical Co., Ltd., Ozonon 6C *7) Ouchi Shinko Chemical Industry Co., Ltd., product name "Noxellar D" *8) Ouchi Shinko Chemical Industry Co., Ltd., product name "Noxellar CZ-G"

[0146] As shown in Tables 3 and 4, it was found that the modified conjugated diene polymers obtained in Examples 1 to 10 can be used to obtain crosslinked bodies with excellent rolling resistance and wear resistance.

Claims

A modified conjugated diene polymer, The weight-average molecular weight (Mw) measured by gel permeation chromatography (GPC) is 10 × 10 ４ The above 200 x 10 ４ The following conditions apply, and the molecular weight distribution (Mw / Mn), expressed as the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn), is between 1.40 and 4.

00. The modification rate relative to the total amount of the modified conjugated diene polymer is 80% or more. Among the modified conjugated diene polymers, the modification rate of the high molecular weight component, which is equal to or greater than the weight-average molecular weight measured by GPC, is 50% or more. A modified conjugated diene polymer in which the modification rate of low molecular weight components, which are less than or equal to the number average molecular weight measured by GPC, is 50% or more. 　 The modified conjugated diene polymer according to claim 1, wherein the ratio of the peak area of ​​a molecular weight of 400,000 or more to the total peak area of ​​the molecular weight distribution curve obtained by GPC measurement is 10% or more. The modified conjugated diene polymer according to claim 1, wherein the Mooney viscosity measured at 100°C is 20 to 150. A linear modified conjugated diene polymer according to claim 1. The modified conjugated diene polymer according to claim 1, wherein the silicon content is 70 ppm or more. The modified conjugated diene polymer according to claim 1, wherein the nitrogen content is 70 ppm or more. 　 The modified conjugated diene polymer according to claim 1, comprising a molecule having a substructure derived from a compound (M) having a silicon atom at at least one end of the polymer chain. 　 The modified conjugated diene polymer according to claim 7, wherein the compound (M) further has a nitrogen atom. 　 The modified conjugated diene polymer according to claim 7, wherein the compound (M) is represented by the following formula (1). In Formula (1), X １ is a group represented by the following formula (1-1) or formula (1-2). A １ is an (i+k)-valent hydrocarbon group having 1 to 20 carbon atoms, or is an (i+k)-valent group having 1 to 20 carbon atoms, containing one or both of nitrogen and oxygen atoms, having no active hydrogen, and bonding to each of X １ and the group "-Si(R １ ) ｎ (OR ２ ) ３－ｎ " via a carbon atom. R １ and R ２ are each independently a hydrocarbyl group having 1 to 20 carbon atoms. n is an integer of 0 to 2. When n is 0 or 1, a plurality of OR ２ are the same or different. If n is 2, multiple R １ They are the same or different. i and k are independent integers from 1 to 6, provided that i + k ≤ 10. In equation (1), if i is 2 or greater, multiple X １ They are the same or different. If k is 2 or more, there are multiple groups "-Si(R １ ) ｎ (OR ２ ) ３－ｎ (These are either the same or different.) (In formula (1-1), R ５ R is a monovalent group having a structure in which a hydrogen atom, a C1-C8 alkyl halide, or an aromatic ring is bonded to a halogen atom or a methyl group. ６ and R ７ These are hydroxylene groups with 1 to 10 carbon atoms, independently of each other. Q １ and Q ２ These are nitrogen atoms or -CR atoms, independently of each other. １０ -. However, R ５ If Q is a hydrogen atom, １ R is a nitrogen atom. １０ is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms. * represents a bond. In formula (1-2), R ８ R is a monovalent group having a structure in which a hydrogen atom, a C1-C8 alkyl halide, or an aromatic ring is bonded to a halogen atom or a methyl group. ９ R is a hydrocarbyl group or trihydrocarbylsilyl group having 1 to 20 carbon atoms. ８ If R is a hydrogen atom, ９ This is a hydrocarbyl group with 1 to 20 carbon atoms. (* indicates a bond.) 　 A modified conjugated diene polymer according to any one of claims 1 to 9, Filler and, A polymer composition containing [the specified ingredient]. 　 The polymer composition according to claim 10, further comprising at least one rubber component selected from the group consisting of natural rubber, isoprene rubber, butadiene rubber, emulsion polymerized styrene-butadiene rubber, solution polymerized styrene-butadiene rubber, hydrogenated butadiene rubber, hydrogenated styrene-butadiene rubber, butyl rubber, halogenated butyl rubber, ethylene-propylene rubber, and ethylene-butadiene rubber, which is different from the modified conjugated diene polymer. 　 A crosslinked body obtained by crosslinking the polymer composition according to claim 10. 　 A tire having a tread, a sidewall, or both formed using the polymer composition described in claim 10. 　 A method for producing a modified conjugated diene polymer according to any one of claims 1 to 9, The process includes polymerizing a monomer containing a conjugated diene compound by a batch polymerization method in the presence of a polymerization initiator. A method for producing a modified conjugated diene polymer, wherein the polymerization initiator is added to the reactor in multiple portions during polymerization. 　 A method for producing a modified conjugated diene polymer according to any one of claims 1 to 9, A method for producing a modified conjugated diene polymer, comprising the step of polymerizing a monomer containing a conjugated diene compound by a continuous polymerization method in the presence of a polymerization initiator.

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