WO2022024219A1

WO2022024219A1 - Polymer composition, crosslinked polymer, and tire

Info

Publication number: WO2022024219A1
Application number: PCT/JP2020/028893
Authority: WO
Inventors: 瀚洋秦
Original assignee: Jsr株式会社
Priority date: 2020-07-28
Filing date: 2020-07-28
Publication date: 2022-02-03

Abstract

Provided is a polymer composition which is easily kneaded due to excellent processability, and is suitable for manufacturing a tire having an excellent, high level of balance in terms of breaking strength, abrasion resistance, and low fuel consumption.　A polymer composition according to the present invention comprises: (A) a conjugated diene-based polymer which is a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound, and which is a reaction product of an active polymerization terminal and a compound represented by general formula (1); (B) a first silica having a CTAB specific surface area of at least 150 m²/g and a BET specific surface area of at least 160 m²/g; and (C) a second silica having a CTAB specific surface area of at most 130 m²/g and a BET specific surface area of at most 140 m²/g.

Description

Polymer compositions, crosslinked polymers, and tires

The present invention relates to a polymer composition, a crosslinked polymer, and a tire made by using the crosslinked polymer.

In recent years, there has been an increasing demand for fuel efficiency of automobiles in connection with the movement of global carbon dioxide emission regulations accompanying the growing interest in environmental issues. In order to meet such demands, it is required to reduce rolling resistance in terms of tire performance. Conventionally, as a method for reducing the rolling resistance of a tire, a method for optimizing the tire structure has been studied, but the polymer composition applied to the tire has a low tan δ (hereinafter, also referred to as “low loss property”). .), The use of excellent low heat generation is also currently practiced as a general method.

As a method for obtaining such a polymer composition having low heat generation property, it is conceivable to reduce the amount of a filler such as carbon black or silica, or to use carbon black having a large particle size. It is inevitable that the reinforcing property, wear resistance and grip property on a wet road surface (hereinafter, also referred to as "wet grip property") of the composition will be deteriorated.

Therefore, for example, studies have been made on using a modified conjugated diene-based polymer in which an active polymer having a metal terminal is formed and modified by introducing a specific modifying agent into the active polymer as a tread material for a tire. (See, for example, Patent Document 1). Patent Document 1 discloses that when this material is used as a tread material for a tire, it is excellent in heat generation, wear resistance, and wet grip.

Special Table 2016-528369 Publication No.

However, when the modified conjugated diene polymer disclosed in Patent Document 1 is used as a tread material for a tire, the modified conjugated diene polymer has a strong interaction with silica and is therefore inferior in processability and is sufficiently kneaded. Since this is not possible, there is a problem that sufficient performance cannot be obtained in terms of breaking strength, wear resistance and fuel efficiency.

Therefore, some aspects of the present invention are suitable for producing a tire that is easy to knead because of its excellent workability and has a high balance in breaking strength, wear resistance and fuel efficiency. I will provide a. In addition, some aspects of the present invention provide a tire that is highly balanced in breaking strength, wear resistance and fuel economy.

The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as any of the following aspects.

One aspect of the polymer composition according to the present invention is
(A) A conjugated diene, which is a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound, which is a reaction product of an active polymerization terminal and a compound represented by the following general formula (1). With the system polymer,
(B) First silica having a CTAB specific surface area of 150 m ² / g or more and a BET specific surface area of 160 m ² / g or more.
(C) Second silica having a CTAB specific surface area of 130 m ² / g or less and a BET specific surface area of 140 m ² / g or less.
Contains.

(In the formula (1), Z is independently a hydrocarbyl group having 1 to 8 carbon atoms or a hydrocarbylviloxy group having 1 to 8 carbon atoms, and one or more of Z bonded to each Si has 1 to 8 carbon atoms. 8 hydrocarbyloxy groups. R ¹ , R ² and R ³ are independently hydrocarbylene groups having 1 to 8 carbon atoms, and A is one of the following formulas (2) to (4). It is a group represented by.)

(In formulas (2) to (4), * is a site that binds to R ³ in the above formula (1). In formulas (2) and (4), Z independently has 1 to 8 carbon atoms. Hydrocarbyl group or hydrocarbyloxy group having 1 to 8 carbon atoms, and one or more of Z bonded to each Si is a hydrocarbyloxy group having 1 to 8 carbon atoms. R ⁴ and R ⁵ are independent of each other. It is a hydrocarbylene group having 1 to 8 carbon atoms.)

In one aspect of the polymer composition,
The first silica (B) can be contained in an amount of 20 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the (A) conjugated diene-based polymer.

In any aspect of the polymer composition
The second silica (C) can be contained in an amount of 20 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the (A) conjugated diene-based polymer.

In any aspect of the polymer composition
The (B) first silica and the (C) second silica can be contained in an amount ratio of 25:75 to 75:25 on a mass basis.

In any aspect of the polymer composition
The polystyrene-equivalent weight average molecular weight of the (A) conjugated diene-based polymer as measured by gel permeation chromatography can be 10,000 to 2,000,000.

In any aspect of the polymer composition
Further, a cross-linking agent can be contained.

One aspect of the crosslinked polymer according to the present invention is
It is produced by using the polymer composition of any one of the above embodiments.

One aspect of the tire according to the present invention is
It is the one using the crosslinked polymer of the said aspect.

According to the polymer composition according to the present invention, it is possible to produce a crosslinked polymer (tire) which is easy to knead because it is excellent in processability and has a high balance in breaking strength, wear resistance and fuel efficiency. can.

Hereinafter, preferred embodiments according to the present invention will be described in detail. It should be noted that the present invention is not limited to the embodiments described below, but should be understood to include various modifications to be carried out without changing the gist of the present invention.

In the present specification, the numerical range described by using "XY" means that the numerical value X is included as the lower limit value and the numerical value Y is included as the upper limit value.

In the present specification, "(meth) acrylic acid-" is a concept including both acrylic acid-and methacrylic acid-.

1. 1. Polymer composition The polymer composition according to the present embodiment is (A) a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound, and has an active polymerization terminal and the following general formula (1). ), Which is a reaction product with the compound represented by), and (B) the first silica having a CTAB specific surface area of 150 m ² / g or more and a BET specific surface area of 160 m ² / g or more. , (C) Second silica having a CTAB specific surface area of 130 m ² / g or less and a BET specific surface area of 140 m ² / g or less.

The polymer composition according to the present embodiment includes (A) a polymer component containing a conjugated diene-based polymer, (B) first silica, (C) second silica, and other additives as necessary. It is an unvulcanized polymer composition obtained by kneading with. The polymer composition according to the present embodiment forms a crosslinked polymer by subjecting it to a crosslinking treatment such as vulcanization.

Hereinafter, each component contained in the polymer composition according to the present embodiment will be described.

1.1. (A) Conjugated Diene Polymer The polymer composition according to the present embodiment is (A) a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound, and has an active polymerization terminal and the following. It contains a conjugated diene-based polymer (also simply referred to as "(A) conjugated diene-based polymer" in the present specification), which is a reaction product with the compound represented by the general formula (1).

(In formulas (2) to (4), * is a site that binds to R ³ in the above formula (1). In formulas (2) and (4), Z has 1 to 8 carbon atoms independently. Hydrocarbyl group or hydrocarbyloxy group having 1 to 8 carbon atoms, and one or more of Z bonded to each Si is a hydrocarbyloxy group having 1 to 8 carbon atoms. R ⁴ and R ⁵ are independent of each other. It is a hydrocarbylene group having 1 to 8 carbon atoms.)

(A) The conjugated diene-based polymer has a structural unit derived from the conjugated diene compound, and has a structure derived from the compound of the above general formula (1) at the terminal of active polymerization. In such a (A) conjugated diene-based polymer, first, a monomer containing a conjugated diene compound is polymerized to obtain a polymer having an active terminal (polymerization step), and then a polymer having an active terminal is obtained. , Can be obtained by reacting with the compound of the above general formula (1) (hereinafter, also referred to as "specific modifier") (modification step).

<Polymerization process>
Examples of the conjugated diene compound that can be used in the polymerization include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. , 2-Phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, 2-chloro-1,3-butadiene and the like. Among these, 1,3-butadiene, isoprene and 2,3-dimethyl-1,3-butadiene are preferable. Conjugated diene compounds may be used alone or in combination of two or more.

(A) The conjugated diene-based polymer may be a homopolymer of the conjugated diene compound, but is a copolymer of the conjugated diene compound and the aromatic vinyl compound from the viewpoint of increasing the strength of the crosslinked polymer. Is preferable. Above all, a copolymer containing 1,3-butadiene and styrene in a monomer composition is preferable in terms of high living property in anionic polymerization. When the (A) conjugated diene-based polymer is a copolymer of a conjugated diene compound and an aromatic vinyl compound, the (A) conjugated diene-based polymer is typically a conjugated diene compound and an aromatic vinyl compound. It may have a random copolymerized moiety having an irregular distribution of, and further have a block moiety composed of structural units derived from a conjugated diene compound or an aromatic vinyl compound.

Examples of the aromatic vinyl compound that can be used in the polymerization include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, and the like. 5-tert-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl) dimethylaminoethyl ether, N, N-dimethyl Aminoethyl styrene, N, N-dimethylaminomethyl styrene, 2-ethyl styrene, 3-ethyl styrene, 4-ethyl styrene, 2-tert-butyl styrene, 3-tert-butyl styrene, 4-tert-butyl styrene, vinyl Examples thereof include xylene, vinylnaphthalene, vinylpyridine, diphenylethylene, tertiary amino group-containing diphenylethylene (for example, 1- (4-N, N-dimethylaminophenyl) -1-phenylethylene, etc.). Among these, styrene and α-methylstyrene are preferable. The aromatic vinyl compound may be used alone or in combination of two or more.

(A) When the conjugated diene polymer is a copolymer of a conjugated diene compound and an aromatic vinyl compound, the content of the aromatic vinyl compound (aromatic vinyl content) is the low loss property of the obtained crosslinked polymer. From the viewpoint of improving the balance between the and wet grip properties, the content is preferably 3 to 55% by mass, preferably 5 to 50% by mass, based on 100% by mass of the total of the conjugated diene compound and the aromatic vinyl compound used for the polymerization. It is more preferable to do so. The aromatic vinyl content of the (A) conjugated diene polymer can be measured by ¹ H-NMR.

In the polymerization, a monomer other than the conjugated diene compound and the aromatic vinyl compound may be used. Examples of other monomers include acrylonitrile, methyl (meth) acrylate, ethyl (meth) acrylate, hydroxyethyl (meth) acrylate and the like. The amount of the other monomers used is preferably 25% by mass or less, more preferably 15% by mass or less, and more preferably 10% by mass or less, based on 100% by mass of the total amount of the monomers used for the polymerization. Especially preferable.

As the polymerization method to be used, any of a solution polymerization method, a gas phase polymerization method and a bulk polymerization method may be used, but the solution polymerization method is particularly preferable. Further, as the polymerization type, either a batch type or a continuous type may be used. When the solution polymerization method is used, as an example of a specific polymerization method, a monomer containing a conjugated diene compound is polymerized in an organic solvent in the presence of a polymerization initiator and a randomizer used as necessary. The method can be mentioned.

As the polymerization initiator, an alkali metal compound or an alkaline earth metal compound can be used. Specific examples of these include alkyllithium such as methyllithium, ethyllithium, n-propyllithium, n-butyllithium, sec-butyllithium and tert-butyllithium, 1,4-dilithiobtan, phenyllithium and stillbenlithium. Lithium naphthyl, 1,3-bis (1-lithio-1,3-dimethylpentyl) benzene, 1,3-phenylenebis (3-methyl-1-phenylpentylidene) dilithium, 3- (dimethylamino) propyllithium, Examples thereof include sodium naphthyl, potassium naphthyl, di-n-butylmagnesium, di-n-hexylmagnesium, ethoxypotassium, calcium stearate and the like. Among these, lithium compounds are preferable. The total amount of the polymerization initiator used is preferably 0.2 to 20 mmol with respect to 100 g of the monomer used for the polymerization. The polymerization initiator may be used alone or in combination of two or more.

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

The modification initiator is preferably a reaction product of a lithium compound such as alkyllithium and a nitrogen-containing compound such as a secondary amine compound. Specific examples of the nitrogen-containing compound include, for example, dimethylamine, diethylamine, dipropylamine, dibutylamine, dodecamethyleneimine, N, N'-dimethyl-N'-trimethylsilyl-1,6-diaminohexane, piperidine, pyrrolidine, and the like. Hexamethylene imine, heptamethylene imine, dicyclohexylamine, N-methylbenzylamine, di- (2-ethylhexyl) amine, diallylamine, morpholine, N- (trimethylsilyl) piperidine, N- (tert-butyldimethylsilyl) piperidine, 1, Examples thereof include 3-ditrimethylsilyl-1,3,5-triazinan and the like. When polymerization is carried out in the presence of a modification initiator, a modification initiator is prepared by previously mixing an alkali metal compound or an alkaline earth metal compound with a compound having a functional group that interacts with silica. The prepared modification initiator may be added to the polymerization system to carry out the polymerization. Alternatively, an alkali metal compound or an alkaline earth metal compound and a compound having a functional group that interacts with silica are added to the polymerization system, and both are mixed in the polymerization system to prepare a modification initiator. Polymerization may be carried out. Alternatively, a nitrogen-containing alkyllithium compound can also be used. As a specific example of the nitrogen-containing alkyllithium compound, a reaction product of 3-dimethylaminopropyllithium and isoprene can be used.

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

The organic solvent used for the polymerization may be any organic solvent that is inert to the reaction, and for example, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons and the like can be used. Of these, hydrocarbons having 3 to 8 carbon atoms are preferable, and specific examples thereof include propane, n-butene, isobutane, n-pentane, isopentan, n-hexane, cyclohexane, propene, 1-butene, isobutene, and trans-. 2-butene, cis-2-butene, 1-pentyne, 2-pentyne, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene, heptane, cyclopentane, methylcyclopentane, methylcyclohexane, 1-pentene, 2-Pentene, cyclohexene and the like can be mentioned. The organic solvent may be used alone or in combination of two or more.

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

For the conjugated diene-based polymer having an active terminal, the vinyl bond content in the structural unit derived from the conjugated diene compound is preferably 30 to 65 mol%, more preferably 33 to 62 mol%, and 35 to 35 to It is particularly preferably 60 mol%. If the vinyl bond content is less than 30 mol%, the grip characteristics tend to be too low, and if it exceeds 65 mol%, the wear resistance of the obtained crosslinked polymer tends to deteriorate. In the present specification, the "vinyl bond content" is a value indicating the content ratio of the structural unit having a vinyl bond to all the structural units derived from the conjugated diene compound in the conjugated diene-based polymer, and is ¹ H-. It is a value measured by NMR.

<Denaturation process>
Next, the conjugated diene-based polymer obtained by the above polymerization reaction is reacted with the active terminal of the polymer with a compound (specific modifier) represented by the following general formula (1). By going through such a step, the (A) conjugated diene-based polymer end-modified with a specific modifying agent can be obtained. The (A) conjugated diene-based polymer terminal-modified with such a specific modifier has a strong interaction with (B) first silica and (C) second silica at the terminal modification site, so that the breaking strength and breaking strength and Abrasion resistance is improved, and rigidity at low strain is increased, so steering stability is also improved.

In the above formulas (1) to (4), the hydrocarbylene group having 1 to 8 carbon atoms of R ¹ to R ⁵ is a linear or branched alkylene group having 1 to 8 carbon atoms and 3 to 3 carbon atoms. Examples thereof include a cycloalkylene group of 8 and an arylene group having 6 to 8 carbon atoms. In the above formulas (1) to (4), as the hydrocarbyl group having 1 to 8 carbon atoms of Z, a linear or branched alkyl group having 1 to 8 carbon atoms and a cycloalkyl group having 3 to 8 carbon atoms are used. Can be mentioned. Further, in the above formulas (1) to (4), the hydrocarbyloxy group having 1 to 8 carbon atoms of Z is a linear or branched alkoxy group having 1 to 8 carbon atoms and a cyclo having 3 to 8 carbon atoms. Alkoxy groups can be mentioned.

In the above formula (1), one or more of Z bonded to each Si is a hydrocarbyloxy group having 1 to 8 carbon atoms, but at the terminal modification site, (B) first silica and (C) second silica are used. From the viewpoint of strengthening the interaction between the two, it is preferable that all three Zs bonded to each Si are hydrocarbyloxy groups having 1 to 8 carbon atoms.

Specific examples of the compound represented by the above general formula (1) include N, N, N', N'-tetrakis (3-trimethoxysilylpropyl) -1,3-diaminopropane, N, N, N'. , N'-Tetrakiss (3-triethoxysilylpropyl) -1,3-diaminopropane, N- (3-imidazolylpropyl) -N, N-bis (3-trimethoxysilylpropyl) amine, N- (3-) Examples thereof include imidazolylpropyl) -N, N-bis (3-triethoxysilylpropyl) amine.

In the modification reaction of the conjugated diene polymer having an active terminal, the specific modifier may be used alone, but the specific modifier and the modifier other than the specific modifier (hereinafter, "other modifiers") Also called.) May be used. The other modifier is particularly limited as long as it is a compound having a functional group that interacts with an inorganic filler such as (B) first silica and (C) second silica and that can react with the active terminal of the polymer. Not done.

The above denaturation reaction can be performed, for example, as a solution reaction. This solution reaction may be carried out using a solution containing an unreacted monomer after the completion of the polymerization reaction. The conjugated diene polymer contained in the solution may be isolated and dissolved in an appropriate solvent such as cyclohexane. You may go. Further, the denaturation reaction may be carried out by either a batch type or a continuous type. At this time, the method of adding the denaturing agent is not particularly limited, and examples thereof include a method of adding the denaturing agent all at once, a method of adding the denaturing agent in portions, and a method of continuously adding the denaturing agent.

The ratio of the specific modifier (the total amount when two or more kinds are used) is preferably 0.2 mol or more with respect to 1 mol of the metal atom involved in the polymerization reaction of the polymerization initiator. It is more preferably 0.4 mol or more. By setting the amount to 0.2 mol or more, the modification reaction of the polymer terminal by the specific modifying agent can be sufficiently proceeded, and the interaction with (B) first silica and (C) second silica at the terminal modification site can be sufficiently promoted. Can be strong enough. Further, in terms of reducing the amount of unreacted substances in the solution after the modification reaction, the upper limit of the usage ratio of the specific modifier is 1.5 with respect to 1 mol of the metal atom involved in the polymerization reaction of the polymerization initiator. The amount is preferably less than 1.2 mol, more preferably less than 1.2 mol.

When the specific denaturing agent and other denaturing agents are used in combination in the denaturing reaction, the ratio of the other denaturing agents used is specified from the viewpoint of sufficiently advancing the reaction between the conjugated diene polymer and the specific denaturing agent. The total usage ratio of the denaturing agent and other denaturing agents is preferably 30 mol% or less, more preferably 20 mol% or less, and particularly preferably 10 mol% or less.

The temperature of the denaturation reaction is usually the same as the temperature of the polymerization reaction, preferably −20 ° C. to 150 ° C., more preferably 0 ° C. to 120 ° C., and preferably 20 ° C. to 100 ° C. Especially preferable. When the temperature of the denaturation reaction is low, the viscosity of the conjugated diene-based polymer after denaturation tends to increase. On the other hand, when the temperature of the denaturation reaction is high, the active end of the polymer is likely to be deactivated. The reaction time of the denaturation reaction is preferably 1 minute to 5 hours, more preferably 2 minutes to 1 hour.

The (A) conjugated diene polymer contained in the reaction solution can be isolated by a known desolvation method such as steam stripping and a drying operation such as heat treatment. The obtained (A) conjugated diene-based polymer may have Mooney viscosity adjusted by adding stretching oil or the like, if necessary. By this treatment, workability can be improved. Examples of the spreading oil include aroma oil, naphthenic oil, paraffin oil and the like. The blending amount of the spreading oil may be appropriately set according to the monomer and the like used for the polymerization, and is, for example, 10 to 50 parts by mass with respect to 100 parts by mass of the conjugated diene-based polymer.

In this way, the (A) conjugated diene-based polymer can be obtained. According to the (A) conjugated diene-based polymer, the dispersibility of (B) first silica and (C) second silica can be improved. This makes it possible to obtain a crosslinked polymer that can simultaneously improve the low loss performance and wear resistance required for applications such as automobile tires. Further, according to the (A) conjugated diene-based polymer, a polymer composition having good processability can be obtained.

The conjugated diene polymer (A) preferably has a structure derived from the compound of the general formula (1) at at least one end of the polymer. Since the conjugated diene polymer (A) has such a structure, the dispersibility of (B) first silica and (C) second silica is further improved when applied to, for example, tire applications, and low loss is achieved. It is preferable in that it exhibits a higher improvement effect in terms of properties and wear resistance.

(A) The polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of the conjugated diene polymer is preferably 10,000 to 2,000,000. When Mw is smaller than 10,000, the crosslinked polymer of the polymer composition according to the present embodiment tends to have low loss resistance and wear resistance, and when it is larger than 2,000,000, it tends to be deteriorated. The processability of the polymer composition tends to decrease. The weight average molecular weight (Mw) of the obtained (A) conjugated diene polymer is more preferably 30,000 to 1,500,000, still more preferably 50,000 to 1,000,000.

(A) The molecular weight distribution of the conjugated diene polymer, that is, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 1.5 to 3.0, more preferably. Is 1.5 to 2.5, and particularly preferably 1.5 to 2.2. (A) When the molecular weight distribution of the conjugated diene polymer is within the above range, more excellent low loss property, wear resistance, wet grip performance and mechanical properties can be easily obtained.

1.2. (B) First silica and (C) Second silica The polymer composition according to the present embodiment has (B) a CTAB specific surface area of 150 m ² / g or more and a BET specific surface area of 160 m ² / g or more. The first silica (also simply referred to as "(B) first silica" in the present specification) and (C) the CTAB specific surface area is 130 m ² / g or less, and the BET specific surface area is 140 m ² / g or less. It contains a second silica (also simply referred to as "(C) second silica" in the present specification). By using (B) the first silica and (C) the second silica in combination, the first silica having a small average primary particle diameter but a relatively large aggregate size is satisfactorily dispersed in the polymer composition. It is possible to make it. By improving the dispersibility of the first silica, the processability of the polymer composition is improved, and a crosslinked polymer (tire) having excellent rubber breaking strength, wear resistance and fuel efficiency can be obtained. can.

(B) The CTAB (cetyltrimethylammonium bromide) specific surface area of the first silica is 150 m ² / g or more, preferably 160 m ² / g or more, more preferably 170 m ² / g or more, and particularly preferably 180 m ² / g or more. Is. When the CTAB specific surface area is less than 150 m ² / g, it tends to be difficult to obtain sufficient improvement in rubber breaking strength and wear resistance. The CTAB specific surface area of (B) first silica is preferably 600 m ² / g or less, more preferably 300 m ² / g or less, and particularly preferably 250 m ² / g or less. If the CTAB specific surface area exceeds 600 m ² / g, the dispersibility is inferior and the particles aggregate, so that the performance of the obtained crosslinked polymer (tire) tends to deteriorate. The CTAB specific surface area of silica is measured according to ASTM D3765-92.

(B) The BET specific surface area of the first silica is 160 m ² / g or more, preferably 175 m ² / g or more, and more preferably 190 m ² / g or more. When the BET specific surface area is less than 160 m ² / g, it tends to be difficult to obtain sufficient improvement in rubber breaking strength and wear resistance. The BET specific surface area of (B) first silica is preferably 600 m ² / g or less, more preferably 300 m ² / g or less, and particularly preferably 260 m ² / g or less. If the BET specific surface area exceeds 600 m ² / g, the dispersibility is inferior and aggregated, so that the performance of the obtained crosslinked polymer (tire) tends to deteriorate. The BET specific surface area of silica is measured according to ASTM D3037-81.

(B) The aggregate size of the first silica is preferably 45 nm or more, more preferably 50 nm or more, and particularly preferably 60 nm or more. (B) Since the first silica has such an aggregate size, it is possible to impart excellent fuel efficiency and wear resistance to the crosslinked polymer while having good dispersibility (workability). The silica aggregate size is measured by a disc centrifugal sedimentation type particle size analysis method.

(B) The average primary particle size of the first silica is preferably 25 nm or less, more preferably 22 nm or less, still more preferably 17 nm or less, and particularly preferably 14 nm or less. The average primary particle size of (B) first silica is preferably 3 nm or more, more preferably 5 nm or more, and particularly preferably 7 nm or more. Although it has such a small average primary particle size, the structure having the above-mentioned aggregate size can further improve the dispersibility (workability) of silica, and further improve fuel efficiency and wear resistance. The average primary particle size of silica can be determined by observing silica with a transmission electron microscope or a scanning electron microscope, measuring the particle size of 400 primary particles of silica observed in the visual field, and averaging them. can.

The content of (B) first silica in the polymer composition according to the present embodiment is preferably 20 parts by mass or more and 70 parts by mass or less, more preferably, with respect to 100 parts by mass of the (A) conjugated diene-based polymer. Is 20 parts by mass or more and 60 parts by mass or less, and particularly preferably 25 parts by mass or more and 50 parts by mass or less. (B) When the content of the first silica is within the above range, the obtained crosslinked polymer (tire) is provided with excellent fuel efficiency and wear resistance while having good dispersibility (workability). Can be done.

(C) The CTAB specific surface area of the second silica is 130 m ² / g or less, preferably 120 m ² / g or less, more preferably 100 m ² / g or less, and particularly preferably 80 m ² / g or less. If the CTAB specific surface area exceeds 130 m ² / g, the dispersibility of (C) second silica deteriorates, and it may be difficult to improve the rubber breaking strength and wear resistance. The CTAB specific surface area of (C) second silica is preferably 10 m ² / g or more, more preferably 20 m ² / g or more, and particularly preferably 40 m ² / g or more. If the CTAB specific surface area is less than 10 m ² / g, the reinforcing property may be low, and it may be difficult to secure the mechanical strength and wear resistance required for the crosslinked polymer.

(C) The BET specific surface area of the second silica is 140 m ² / g or less, preferably 120 m ² / g or less, more preferably 100 m ² / g or less, and particularly preferably 90 m ² / g or less. If the BET specific surface area exceeds 140 m ² / g, the dispersibility of (C) second silica deteriorates, and it may be difficult to improve the rubber breaking strength and wear resistance. The BET specific surface area of (C) second silica is preferably 10 m ² / g or more, more preferably 20 m ² / g or more, and particularly preferably 30 m ² / g or more. If the BET specific surface area is less than 10 m ² / g, the reinforcing property may be low, and it may be difficult to secure the mechanical strength and wear resistance required for the crosslinked polymer.

(C) The average primary particle size of the second silica is preferably 20 nm or more, more preferably 25 nm or more, further preferably 30 nm or more, particularly preferably 35 nm or more, and most preferably 55 nm or more. The average primary particle size of (C) second silica is preferably 500 nm or less, more preferably 200 nm or less, still more preferably 100 nm or less, and particularly preferably 70 nm or less. Having such an average primary particle size may improve rubber breaking strength and wear resistance.

The content of (C) second silica in the polymer composition according to the present embodiment is preferably 20 parts by mass or more and 70 parts by mass or less, more preferably, with respect to 100 parts by mass of the (A) conjugated diene-based polymer. Is 20 parts by mass or more and 60 parts by mass or less, and particularly preferably 25 parts by mass or more and 50 parts by mass or less. (C) When the content of the second silica is in the above range, excellent rubber breaking strength and wear resistance can be imparted to the obtained crosslinked polymer (tire).

In the polymer composition according to the present embodiment, the total content of silica containing (B) first silica and (C) second silica is preferably (A) with respect to 100 parts by mass of the conjugated diene polymer. It is 20 parts by mass or more, more preferably 30 parts by mass or more, further preferably 40 parts by mass or more, and particularly preferably 45 parts by mass or more. When the total content of silica is less than the above range, it is necessary to increase the blending amount of carbon black, which is not preferable in terms of fuel efficiency. The total content of silica is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, and particularly preferably 80 parts by mass or less. When the total content of silica exceeds the above range, the total content of silica and carbon black is contained when the minimum amount (about 10 parts by mass) of carbon black necessary for improving weather resistance (ultraviolet crack resistance) and coloring is blended. Since the amount is excessive, the fuel efficiency tends to deteriorate, and the filler may be too much to impair the workability.

The CTAB specific surface area of the entire silica contained in the polymer composition according to the present embodiment is preferably in the range of 115 to 130 m ² / g. When the CTAB specific surface area of the entire silica is within the above range, the dispersibility of the silica is improved, so that the processability of the polymer composition becomes better, and the polymer composition has excellent rubber breaking strength, wear resistance and low fuel consumption. A crosslinked polymer (tire) can be obtained.

Further, in the polymer composition according to the present embodiment, it is preferable that (B) first silica and (C) second silica are contained in an amount ratio of 25:75 to 75:25 on a mass basis, 40. It is more preferable to contain it in an amount ratio of: 60 to 60:40. By containing (B) the first silica and (C) the second silica in the above-mentioned amount ratio, the dispersibility of the silica is improved, so that the processability of the polymer composition becomes better, and the excellent rubber. A crosslinked polymer (tire) having breaking strength, wear resistance and low fuel consumption can be obtained.

The polymer composition according to the present embodiment may contain silica other than (B) first silica and (C) second silica. The total content of (B) first silica and (C) second silica in 100% by mass of the inorganic filler contained in the polymer composition according to the present embodiment is preferably 80% by mass or more. It is preferably 90% by mass or more. When the total content of (B) 1st silica and (C) 2nd silica is less than the above range, the use of carbon black as the remaining inorganic filler tends to deteriorate the wet grip performance, and carbon The use of fillers other than black may reduce wear resistance.

1.3. Other Ingredients In addition to the above-mentioned components, the polymer composition according to the present embodiment contains, if necessary, other diene-based polymers other than (A) conjugated diene-based polymer, (B) first silica, and (C) Other inorganic fillers other than the second silica, silane coupling agents, cross-linking agents, acidic compounds, spreading oils (process oils), antiaging agents, vulcanization accelerators, and vulcanization aids as necessary. Known additives such as agents, processing aids, scorch inhibitors and zinc oxides, softeners, colorants, flame retardants, lubricants, foaming agents, plastics, antioxidants, UV inhibitors, antistatic agents, anticoloring agents, etc. The agent can be used depending on the intended use of the polymer composition.

<Other polymers>
The polymer composition according to the present embodiment may contain a diene-based polymer other than the (A) conjugated diene-based polymer. Such a diene-based polymer is not particularly limited as long as it has a repeating unit derived from a conjugated diene compound, and for example, natural rubber, polybutadiene, polyisoprene, ethylene-propylene-diene rubber, styrene-butadiene rubber, acrylonitrile-. Examples include butadiene rubber.

When the polymer composition according to the present embodiment contains other polymers, the content of the other polymers is when the total amount of the polymer components contained in the polymer composition is 100 parts by mass. It is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and particularly preferably 35 parts by mass or less.

<Other inorganic fillers>
The polymer composition according to the present embodiment is other than (B) first silica and (C) second silica in order to further improve the low loss property, wear resistance and wet grip property of the obtained crosslinked polymer. It may contain an inorganic filler. Examples of the inorganic filler include (B) silica other than the first silica and (C) the second silica, carbon black, and a mixture thereof.

The carbon black is not particularly limited, and a general one blended in the rubber composition can be used, and specific examples thereof include GPF, FEF, HAF, ISAF, SAF and the like. Among these, ISAF, SAF and HAF are preferable, and ISAF is more preferable.

The ratio of carbon black used is preferably 0 to 130 parts by mass, and more preferably 2 to 110 parts by mass with respect to 100 parts by mass of the polymer component.

<Silane coupling agent>
Examples of the silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, and bis (2-triethoxy). Cyrilethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyl Trimethoxysilane, 2-mercaptoethyltriethoxysilane; 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxy Cyrilethyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazolyltetrasulfide, 3-triethoxysilylpropylbenzolyltetrasulfide, 3-triethoxysilylpropylmethacrylate monosulfide, 3-tri Methoxysilylpropyl methacrylate monosulfide, bis (3-diethoxymethylsilylpropyl) tetrasulfide, 3-mercaptopropyl dimethoxymethylsilane, dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, dimethoxymethylsilylpropylbenzothiazoli Examples thereof include lutetrasulfide and 3-octanoylthio-1-propyltriethoxysilane. These compounds can be used alone or in combination of two or more. Among these, bis (3-triethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, and 3-trimethoxysilylpropylbenzothiazolyltetra from the viewpoint of improving the reinforcing property. Sulfide is preferred.

The ratio of the silane coupling agent used is preferably 0.5 to 20 parts by mass with respect to 100 parts by mass in total of (B) first silica, (C) second silica and other inorganic filler components. .. When the ratio of the silane coupling agent used is within the above range, sufficient reinforcing properties and fracture resistance can be imparted to the crosslinked polymer formed from the polymer composition, and the wear resistance of the crosslinked polymer is improved. can.

<Crosslinking agent>
Examples of the cross-linking agent include sulfur, sulfur halides, organic peroxides, quinonedioximes, organic polyvalent amine compounds, and alkylphenol resins having a methylol group. Among these, sulfur is usually used as a cross-linking agent. The ratio of the cross-linking agent used is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the polymer component.

<Acid compound>
As the acidic compound, saturated fatty acids having 12 to 24 carbon atoms and metal salts thereof are preferably used. Specific examples of acidic compounds include lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, nonadesilic acid, arachidic acid, henicosyl acid, bechenic acid, tricosyl acid, lignoceric acid, and these. Saturated fatty acids such as calcium salt and zinc salt can be mentioned. These acidic compounds can be used alone or in combination of two or more. Of these, stearic acid is preferred. The ratio of the acidic compound used is preferably 0.3 to 15 parts by mass with respect to 100 parts by mass of the polymer component.

<Other additives>
Examples of the spreading oil include aroma oil, naphthenic oil, paraffin oil and the like. The ratio of the spread oil used is 0 to 50 parts by mass with respect to 100 parts by mass of the polymer component.

Examples of the antiaging agent include N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine and the like. The proportion of the antioxidant used is 0.5 to 5 parts by mass with respect to 100 parts by mass of the polymer component.

Examples of the vulcanization aid include zinc oxide and the like. The ratio of the vulcanization aid used is 1 to 5 parts by mass with respect to 100 parts by mass of the polymer component.

Examples of the vulcanization accelerator include guadinin-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, thiuram-based, dithiocarbamate-based, and zantate-based compounds. Preferred specific examples of the vulcanization accelerator are sulfenamides such as N-cyclohexyl-2-benzothiadylsulfenamide (CBS) and N-tetra-butyl-2-benzothiadylsulfenamide (TBBS). Examples include vulcanization accelerators. The ratio of the vulcanization accelerator to be used is appropriately determined in consideration of the type and ratio of the basic compound, but is preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the polymer component.

1.4. Method for Producing Polymer Composition The polymer composition according to the present embodiment can be prepared by kneading each of the above components using a kneader such as a plast mill, a Banbury mixer, a roll, or an internal mixer. can. For example, it is preferable to prepare by the following method.

<First stage kneading>
In the first-stage kneading, (A) the conjugated diene-based polymer, (B) the first silica and (C) the second silica, and if necessary, other inorganic fillers and silane coupling agents are kneaded. Is preferable. Further, in the first-stage kneading, other polymers, spreading oils, antiaging agents and the like are also kneaded together, if necessary. Further, in the first-stage kneading, the acidic compounds, which are preferably kneaded in the second-stage kneading, may be kneaded together.

By subjecting (B) first silica, (C) second silica and other inorganic fillers to the first-stage kneading, the dispersibility of these is likely to be improved, and a tire formed from the obtained polymer composition ( The low fuel consumption performance of the crosslinked polymer) may be improved.

When a silane coupling agent is used for the first-stage kneading, first, (A) a conjugated diene-based polymer, other polymers, (B) first silica, (C) second silica, and if necessary. It is preferable to knead other inorganic fillers accordingly, and then add (post-add) a silane coupling agent and further knead.

By post-adding the silane coupling agent in the first-stage kneading, the obtained polymer composition becomes more processable, and the crosslinked polymer formed from the polymer composition has more excellent low hysteresis. It will have characteristics. Further, by adding a silane coupling agent afterwards in the first-stage kneading, the dispersibility of (B) first silica and (C) second silica may be improved.

When the silane coupling agent is added afterwards, the timing of adding the silane coupling agent depends on the type of silica, the ratio of silica used, the kneading conditions, etc., and (A) the use of the conjugated diene polymer and other polymers. It is determined as appropriate in consideration of the ratio.

When the silane coupling agent is added afterwards, the (A) conjugated diene polymer and other polymers are blended and kneaded for 0.5 to 10 minutes, and then the silane coupling agent is added. It is preferable to knead for 0.5 to 10 minutes.

Examples of the kneader used for the first-stage kneading include an open type or a closed type kneader such as a plast mill, a Banbury mixer, a roll, and an internal mixer. Further, in the first-stage kneading, the kneading temperature is set to 30 ° C. to 180 ° C., preferably 50 to 160 ° C.

Further, when the silane coupling agent is applied to the first-stage kneading, the method is not limited to the method of adding the silane coupling agent afterwards and kneading, and the silane coupling agent is used for the first-stage kneading. A kneaded product containing a silane coupling agent may be obtained by a method of kneading all the components at the same time. Further, after preparing a masterbatch in which (A) a conjugated diene-based polymer, (B) first silica, (C) second silica, and a silane coupling agent are kneaded, other polymers and additives are added. It may be a method of doing.

<Second stage kneading>
The second-stage kneading is a step of adding at least a cross-linking agent to the kneaded product obtained in the first-stage kneading and kneading the kneaded product and the cross-linking agent to obtain a polymer composition. In this second-stage kneading, it is preferable that the acidic compound is kneaded together with the kneaded product obtained in the first-stage kneading and the cross-linking agent. Further, in the second stage kneading, zinc oxide and the vulcanization accelerator are also kneaded together, if necessary. Then, in the second-stage kneading, all the components normally subjected to the second-stage kneading (specifically, the kneaded product obtained in the first-stage kneading, the cross-linking agent, and, if necessary), are used. A polymer composition is obtained by a method of simultaneously kneading an acidic compound and other components such as zinc oxide and a vulcanization accelerator.

By applying the acidic compound to the second stage kneading, the obtained polymer composition has more excellent processability, and the crosslinked polymer formed from the polymer composition has more excellent low hysteresis characteristics. Will have.

In the second stage kneading, the kneading machine used in the first stage kneading is used. Further, in the second stage kneading, the kneading temperature is set to 30 ° C. to 130 ° C., preferably 50 ° C. to 110 ° C.

The polymer composition obtained by the above-mentioned production method is an unvulcanized rubber composition, and a crosslinked polymer is formed by subjecting it to a crosslinking treatment such as vulcanization, for example.

1.5. Applications The crosslinked polymer formed from the polymer composition according to this embodiment is suitably used as a tire, specifically, a tread of a tire. The tire formed from the polymer composition according to the present embodiment has high strength in the tread and a desired shape in the tread, so that excellent performance can be obtained. Further, the crosslinked polymer formed from the polymer composition according to the present embodiment can also be used as a tire member other than a tread, a vibration-proof rubber, a fender, a belt, a hose, and other industrial products.

2. 2. Examples Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples. In addition, "%" in the following production examples, examples and comparative examples is based on mass unless otherwise specified.

2.1. (A) Production Example of Conjugated Diene Polymer <Production Example 1>
In an autoclave reactor with an internal volume of 16 liters substituted with nitrogen, 1,3-butadiene was 27.3 g / min, styrene was 18.2 g / min, cyclohexane was 237.1 g / min, and tetrahydrofuran was 3.3 g / min. Minutes, n-butyllithium was continuously charged at 0.283 mmol / min (18.11 mg / min) and the reactor temperature was controlled at 75 ° C. The polymer solution was continuously decharged from the first reactor at 321.9 g / min, to which N, N, N', N'-tetrakis (3-triethoxysilylpropyl) -1,3 -Diaminopropane was added at 0.0742 mmol / min, line-mixed, and continuously introduced into the second reactor to carry out the reaction. At the outlet of the second reactor, 0.7 parts by mass of di-tert-butyl-p-cresol was added to 100 parts by mass of the polymer component. Then, the solvent was removed by steam stripping, and the rubber was dried by a heat roll adjusted to 110 ° C. to obtain a modified conjugated diene-based copolymer (hereinafter, also referred to as “SBR-1”).

<Manufacturing example 2>
In Production Example 1, instead of N, N, N', N'-tetrakis (3-triethoxysilylpropyl) -1,3-diaminopropane, N- (3-imidazolylpropyl) -N, N-bis (3-imidazolylpropyl) -N, N-bis ( The same procedure as in Production Example 1 was carried out except that 3-triethoxysilylpropyl) amine was added at 0.0742 mmol / min to obtain a modified conjugated diene-based copolymer (hereinafter, also referred to as “SBR-2”). ..

<Manufacturing example 3>
In Production Example 1, the same operation as in Production Example 1 was performed except that N, N, N', N'-tetrakis (3-triethoxysilylpropyl) -1,3-diaminopropane were not added, and the conjugated diene was performed. A system copolymer (hereinafter, also referred to as “SBR-3”) was obtained.

2.2. Measurement method of physical properties <Measurement of number average molecular weight (Mn) and weight average molecular weight (Mw)>
For each polymer produced above, gel permeation chromatography (GPC) (“HLC-8120” manufactured by Tosoh Corporation) corresponds to the peak of the maximum peak of the GPC curve obtained under the following GPC conditions. From the holding time, the polystyrene-equivalent number average molecular weight (Mn) and weight average molecular weight (Mw) were calculated.
(GPC condition)
Column: Product name "GMHXL" (manufactured by Tosoh Corporation) 2 columns Column temperature: 40 ° C
Mobile phase: Tetrahydrofuran Flow rate: 1.0 ml / min Sample concentration: 10 mg / 20 ml

<Measurement of vinyl content and bound styrene content>
-Vinyl content (%): Measured by ¹ H-NMR measurement at 400 MHz.
-Binding styrene content (%): Measured by ¹ H-NMR measurement at 400 MHz. The bound styrene content is a parameter corresponding to the aromatic vinyl content.

2.3. Examples 1 to 14 and Comparative Examples 1 to 9
2.3.1. Production of Polymer Composition and Crosslinked Polymer Each component was blended according to the compounding formulations shown in Tables 3 to 4 below, and each component was kneaded to produce each polymer composition. Kneading was performed by the following method.

As a plast mill (contents: 250 ml) with a temperature control device, the polymer component shown in Tables 3 to 4 below, silica, under the conditions of a filling rate of 72% and a rotation speed of 60 rpm as the first stage kneading). , Carbon black, silane coupling agent, stearic acid, anti-aging agent, zinc oxide, and spreading oil were kneaded. Next, as the second-stage kneading, the kneaded product obtained above is cooled to room temperature, and then the vulcanization accelerator and sulfur are kneaded to form the polymers of Examples 1 to 14 and Comparative Examples 1 to 9. I got something.

Next, each of the obtained polymer compositions was molded and vulcanized at 160 ° C. for a predetermined time by a vulcanization press to obtain each crosslinked polymer having a predetermined shape to be subjected to the following evaluation test.

2.3.2. Evaluation of Polymer Composition and Crosslinked Polymer The following evaluation tests were performed on each of the obtained polymer compositions and each crosslinked polymer. The results are shown in Tables 3 to 4 below.

<Breaking strength>
In accordance with JIS K6251: 2010, a No. 3 dumbbell type test piece made of a test vulcanized rubber sheet was prepared and used as a test piece for evaluation. Using a tensile tester (model name "AG-2000", manufactured by Shimadzu Corporation), the sample piece was pulled at a load speed of 500 mm / min to determine the breaking strength (TB). In Tables 3 to 4 below, the index is displayed when the measured value of Comparative Example 1 is set to 100, and the larger the value, the higher the intensity.

<Abrasion resistance>
Using a vulcanized rubber as a measurement sample, a DIN wear tester (manufactured by Toyo Seiki Co., Ltd.) was used, and the measurement was performed at 25 ° C. with a load of 10 N in accordance with JIS K6264-2: 2005. In Tables 3 to 4 below, the index is expressed when the measured value of Comparative Example 1 is set to 100, and the larger the value, the better the wear resistance.

<Fuel efficiency (50 ° C tan δ)>
Using vulcanized rubber as a measurement sample, ARES-RDA (manufactured by TA Instruments) was used, and the loss coefficient (tan δ (50 ° C)) was set under the conditions of shear strain 0.7%, angular velocity 100 radians per second, and 50 ° C. It was measured. In Tables 3 to 4 below, the index is expressed as 100 based on the measured value of Comparative Example 1, and the larger the value of tan δ (50 ° C.), the smaller the energy loss and the better the low hysteresis loss characteristic. Show that.

<Workability>
According to JIS K6300-1: 2013, the Mooney viscosity of the polymer composition was determined using an L rotor under the conditions of preheating 1 minute, rotor operating time 4 minutes, and temperature 100 ° C. In Tables 3 to 4 below, the index is expressed as 100 based on the measured value of Comparative Example 1, and the larger the value, the better the workability.

2.4. Evaluation Results Table 1 below shows the physical characteristics of each polymer synthesized above. Table 2 below shows the physical property values of each silica used. Tables 3 to 4 below show the composition and evaluation results of each polymer composition.

In Tables 3 to 4 above, the numerical values of each component in the composition of the polymer composition represent parts by mass. The following products were used as the materials shown in Tables 3 to 4 above.
-Silica B1: Made by Rhodia, trade name "ZEOSIL Premium 200P"
-Silica B2: Made by Rhodia, trade name "ZEOSIL HRS 1200MP"
-Silica B3: Evonik's product name "ULTRASIL VN3"
-Silica C1: Made by Rhodia, trade name "ZEOSIL 1115MP"
-Silica C2: Made by Degussa, trade name "ULTRASIL 360"
-Silica C3: Made by Tosoh Silica, trade name "Nipsil E-743"
・ Extension oil: "X140" manufactured by Japan Energy Co., Ltd.
-Carbon black: Made by Tokai Carbon Co., Ltd., product name "Seast KH"
-Silane coupling agent: Evonik, trade name "Si69"
・ Stearic acid: Made by NOF Corporation, trade name "Beads stearic acid camellia"
-Anti-aging agent: manufactured by Sumitomo Chemical Co., Ltd., product name "Antigen 3C"
-Vulcanization accelerator CZ: manufactured by Sumitomo Chemical Industries, Ltd., trade name "Soxinol CZ", N-cyclohexyl-2-benzothiazolesulfenamide-Vulcanization accelerator D: manufactured by Sumitomo Chemical Industries, Ltd., trade name "Soxinol D" , 1,3-Diphenylguanidine / Sulfur: Manufactured by Tsurumi Chemical Industry Co., Ltd.

From the results of Tables 3 to 4, the polymer compositions according to Examples 1 to 14 consist of (A) conjugated diene-based polymer, (B) first silica, and (C) second silica. By containing it, the processability is improved as compared with the polymer composition according to Comparative Example 1, so that it is easy to knead, and the breaking strength, wear resistance and fuel efficiency are also highly balanced. It was confirmed that the crosslinked polymer was obtained.

The present invention is not limited to the above embodiment, and various modifications are possible. The present invention includes substantially the same configurations as those described in the embodiments (eg, configurations with the same function, method and result, or configurations with the same purpose and effect). The present invention also includes a configuration in which a non-essential part of the configuration described in the above embodiment is replaced with another configuration. Further, the present invention also includes a configuration having the same action and effect as the configuration described in the above embodiment or a configuration capable of achieving the same object. Further, the present invention also includes a configuration in which a known technique is added to the configuration described in the above embodiment.

Claims

(A) A conjugated diene, which is a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound, which is a reaction product of an active polymerization terminal and a compound represented by the following general formula (1). With the system polymer,
(B) First silica having a CTAB specific surface area of 150 m 2 / g or more and a BET specific surface area of 160 m 2 / g or more.
(C) Second silica having a CTAB specific surface area of 130 m 2 / g or less and a BET specific surface area of 140 m 2 / g or less.
A polymer composition containing.

(In the formula (1), Z is independently a hydrocarbyl group having 1 to 8 carbon atoms or a hydrocarbylviloxy group having 1 to 8 carbon atoms, and one or more of Z bonded to each Si has 1 to 8 carbon atoms. 8 hydrocarbyloxy groups. R 1 , R 2 and R 3 are independently hydrocarbylene groups having 1 to 8 carbon atoms, and A is one of the following formulas (2) to (4). It is a group represented by.)

(In formulas (2) to (4), * is a site that binds to R 3 in the above formula (1). In formulas (2) and (4), Z has 1 to 8 carbon atoms independently. Hydrocarbyl group or hydrocarbyloxy group having 1 to 8 carbon atoms, and one or more of Z bonded to each Si is a hydrocarbyloxy group having 1 to 8 carbon atoms. R 4 and R 5 are independent of each other. It is a hydrocarbylene group having 1 to 8 carbon atoms.)
The polymer composition according to claim 1, wherein the (B) first silica is contained in an amount of 20 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the (A) conjugated diene-based polymer.
The polymer composition according to claim 1 or 2, wherein the (C) second silica is contained in an amount of 20 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the (A) conjugated diene-based polymer.
The invention according to any one of claims 1 to 3, wherein the (B) first silica and the (C) second silica are contained in an amount ratio of 25:75 to 75:25 on a mass basis. Polymer composition.
One of claims 1 to 4, wherein the polystyrene-equivalent weight average molecular weight of the (A) conjugated diene-based polymer measured by gel permeation chromatography is 10,000 to 2,000,000. The polymer composition according to.
The polymer composition according to any one of claims 1 to 5, further comprising a cross-linking agent.
A crosslinked polymer produced by using the polymer composition according to claim 6.
A tire using the crosslinked polymer according to claim 7.