JP2016030795A - Method for producing conjugated diene-based rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a conjugated diene-based rubber used for an automobile tire which provides a rubber crosslinked product having excellent morphological stability and excellent low heat generation properties and wet grip performance.SOLUTION: There is provided a method for producing conjugated diene-based rubber, which comprises: a step of polymerizing isoprene or a monomer mixture containing isoprene and an aromatic vinyl monomer in inactive solvent by using polymerization initiator to obtain a polymer block (A) having an active terminal; a step of forming a polymer block (B) composed of 1,3-butadiene or 1,3-butadiene and an aromatic vinyl monomer by continuing the polymerization reaction by mixing the polymer block (A) having an active terminal and 1,3-butadiene or a monomer mixture containing 1,3-butadiene and an aromatic vinyl monomer to obtain a conjugated diene polymer chain having an active terminal which has the polymer block (A) and the polymer block (B); and a step of reacting a compound represented by the formula (1) with the active terminal of the conjugated diene polymer chain having an active terminal.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a conjugated diene rubber, and more specifically, a conjugated diene rubber capable of providing a crosslinked rubber having excellent shape stability, low heat build-up, and excellent wet grip properties. On how to do. The present invention also relates to a conjugated diene rubber obtained by this production method, a rubber composition containing the conjugated diene rubber, and a rubber cross-linked product thereof.

  In recent years, due to environmental problems and resource problems, automobile tires are strongly required to have low heat buildup, and from the viewpoint of safety, excellent wet grip properties and strength are required. A tire obtained using a rubber composition blended with silica as a filler has improved low heat build-up compared to a tire obtained using a rubber composition blended with a conventionally used carbon black. Thus, a tire with lower fuel consumption can be obtained.

  As a conjugated diene rubber used to provide such a fuel-efficient tire, Patent Document 1 discloses a conjugated diene system having an isoprene block at one end of a conjugated diene polymer chain and an active end at the other end. A conjugated diene rubber obtained by reacting a specific tin halide compound with a polymer chain is disclosed. Further, Patent Document 2 discloses that a conjugated diene polymer chain having an isoprene block at one end and an conjugated diene polymer chain having an active terminal at the other end is reacted with a specific modifier at least 3 or more. A conjugated diene rubber containing a predetermined amount or more of a structure formed by bonding the conjugated diene polymer chains is disclosed.

Special Table 2003-53257 International Publication No. 2011/105362

  However, in view of the recent increase in performance requirements for automobile tires, new tires to be developed in the future will be more than tires obtained using conjugated diene rubbers specifically described in these patent documents. There is a demand for a conjugated diene rubber that can produce a tire having both low heat build-up, wet grip and strength. Further, as a rubber composition used for such a tire, in the production process, when processed into a predetermined shape (for example, a veil) from the viewpoint of improving the production stability and handleability, It is also demanded that such a predetermined shape can be maintained well (that is, excellent in shape stability).

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a conjugated diene that can provide a rubber cross-linked product that is excellent in shape stability, low exothermic property, and wet grip properties. It is to provide a method for producing a rubber.

  As a result of diligent research to achieve the above object, the present inventors have used a polymerization initiator in an inert solvent to produce a polymer block (A) having an active terminal containing a specific amount of isoprene monomer units. And then forming the polymer block (B) having an active terminal containing a specific amount of 1,3-butadiene monomer unit and, if necessary, an aromatic vinyl monomer unit. Obtaining a conjugated diene polymer chain having an active end having (A) and the polymer block (B), and subsequently specifying the active end of the conjugated diene polymer chain having the active end By reacting a compound having the following structure, the resulting conjugated diene rubber gives a cross-linked rubber having excellent shape stability, low heat build-up, and excellent wet grip properties. It found that it is possible to, and have completed the present invention.

（上記一般式（１）中、Ｒ^１〜Ｒ^３は、それぞれ、炭素数１〜４のアルキル基であり、Ｒ^４は芳香環を含有する炭素数６〜１０の炭化水素基であり、Ｒ^５は炭素数１〜６のアルキル基であり、ｎは０〜１０の整数である。） That is, according to the present invention, an isoprene monomer or a monomer mixture containing isoprene and an aromatic vinyl monomer is polymerized with a polymerization initiator in an inert solvent, and isoprene monomer units 80 to A step of forming a polymer block (A) having an active terminal containing 100% by weight and 0 to 20% by weight of an aromatic vinyl monomer unit, the polymer block (A) having an active terminal, and 1,3- The polymerization reaction is continued by mixing butadiene or a monomer mixture containing 1,3-butadiene and aromatic vinyl monomer, and 50 to 100% by weight of 1,3-butadiene monomer unit and aromatic By forming a polymer block (B) having an active terminal containing 0 to 50% by weight of vinyl monomer units in a continuous manner with the polymer block (A), the polymer block (A And a step of obtaining a conjugated diene polymer chain having an active terminus having the polymer block (B), and the active terminus of the conjugated diene polymer chain having an active terminus, the following general formula (1) A process for reacting a compound represented by the formula:

(In the general formula ^(1), R 1 ~R ³ are each an alkyl group having 1 to 4 carbon atoms, ^{R 4} is a hydrocarbon group having 6 to 10 carbon atoms containing an aromatic ring, R ⁵ is an alkyl group having 1 to 6 carbon atoms, and n is an integer of 0 to 10.)

（上記一般式（２）中、Ｒ^６は置換基を有していてもよい炭化水素基を表し、Ｘ^１はハロゲン基を表し、Ｍは珪素原子または錫原子を表す。） In the production method of the present invention, after the step of obtaining a conjugated diene polymer chain having an active end having the polymer block (A) and the polymer block (B), a part of the active end is tin halide. It is preferable to further comprise a step of reacting with a compound represented by formula (2) below, silicon halide, or silicon halide.

(In the general formula (2), R ⁶ represents a hydrocarbon group that may have a substituent, X ¹ represents a halogen group, and M represents a silicon atom or a tin atom.)

Moreover, according to this invention, the conjugated diene type rubber | gum obtained by said manufacturing method is provided.
Furthermore, according to this invention, the rubber composition formed by containing 10-200 weight part of silica with respect to 100 weight part of rubber components containing the said conjugated diene-type rubber is provided.
The rubber composition of the present invention preferably contains a crosslinking agent.

  Moreover, according to this invention, the rubber | gum crosslinked material formed by bridge | crosslinking the said rubber composition and the tire containing this rubber | gum crosslinked material are provided.

  ADVANTAGE OF THE INVENTION According to this invention, the conjugated diene rubber which can give the rubber crosslinked material excellent in shape stability, low heat build-up property, and wet grip property, The rubber composition containing this modified conjugated diene rubber It is possible to provide a rubber cross-linked product obtained by cross-linking the rubber composition and having low heat build-up and excellent wet grip properties, and a tire comprising the rubber cross-linked product.

  The method for producing a conjugated diene rubber according to the present invention comprises polymerizing an isoprene monomer or a monomer mixture containing isoprene and an aromatic vinyl monomer in an inert solvent with a polymerization initiator, A step of forming a polymer block (A) having an active terminal containing 80 to 100% by weight of a body unit and 0 to 20% by weight of an aromatic vinyl monomer unit, a polymer block (A) having the active terminal, 1,3-butadiene, or a monomer mixture containing 1,3-butadiene and an aromatic vinyl monomer, to continue the polymerization reaction, and 1,3-butadiene monomer unit 50 to 100 weight And a polymer block (B) having an active end containing 0 to 50% by weight of an aromatic vinyl monomer unit and the polymer block (A) in a continuous manner to form the polymer. The step of obtaining a conjugated diene polymer chain having an active end having a lock (A) and the polymer block (B), and the active end of the conjugated diene polymer chain having the active end will be described later. And a step of reacting the compound represented by the general formula (1).

<Conjugated diene polymer chain having active terminal>
In the method for producing a conjugated diene rubber according to the present invention, first, in an inert solvent, a monomer mixture containing an isoprene monomer or isoprene and an aromatic vinyl monomer is polymerized with a polymerization initiator to obtain isoprene. The step of forming a polymer block (A) having an active end containing 80 to 100% by weight of monomer units and 0 to 20% by weight of an aromatic vinyl monomer unit is carried out, The combined block (A) and 1,3-butadiene, or a monomer mixture containing 1,3-butadiene and an aromatic vinyl monomer are mixed to continue the polymerization reaction, and 1,3-butadiene alone A polymer block (B) having an active terminal containing 50 to 100% by weight of a monomer unit and 0 to 50% by weight of an aromatic vinyl monomer unit is formed continuously with the polymer block (A). It allows having the polymer block (A) and the polymer block (B), performing the step of obtaining a conjugated diene polymer chain having an active terminal.

[Polymer block (A)]
The polymer block (A) in the conjugated diene polymer chain according to the present invention is composed of 80 to 100% by weight of isoprene monomer units and 0 to 20% by weight of aromatic vinyl monomer units in the polymer block (A). %, Isoprene monomer units 85 to 95% by weight and aromatic vinyl monomer units 5 to 15% by weight are preferable, and isoprene monomer units 89 to 95%. More preferably, it contains 5% by weight and 5-11% by weight of aromatic vinyl monomer units. When the content ratio of the isoprene monomer unit and the aromatic vinyl monomer unit is within the above range, the affinity between the conjugated diene rubber and the silica is improved when silica is added to the conjugated diene rubber. Further, the shape stability is improved, and the rubber cross-linked product obtained by using the shape stability can be made excellent in low heat buildup and wet grip properties.

  Examples of the aromatic vinyl monomer used to constitute the aromatic vinyl monomer unit contained in the polymer block (A) include styrene, α-methylstyrene, 2-methylstyrene, and 3-methylstyrene. 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-butyl-2- Examples thereof include methyl styrene, vinyl naphthalene, dimethylaminomethyl styrene, dimethylaminoethyl styrene and the like. Among these, styrene, α-methylstyrene, or 4-methylstyrene is preferable, and styrene is particularly preferable. In addition, these aromatic vinyl monomers may be used individually by 1 type, and may be used in combination of 2 or more type.

  The polymer block (A) is preferably composed only of an isoprene monomer unit and an aromatic vinyl monomer unit. In addition to the monomer unit and the aromatic vinyl monomer unit, other monomer units may be further contained. Other monomers used for constituting other monomer units include 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1 Conjugated diene monomers other than isoprene such as 1,3-pentadiene, and 1,3-hexadiene; α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile; acrylic acid, methacrylic acid, and maleic anhydride Unsaturated rubonic acid or anhydride; unsaturated carboxylic acid esters such as methyl methacrylate, ethyl acrylate, and butyl acrylate; 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclo Non-conjugated dienes such as pentadiene and 5-ethylidene-2-norbornene; and the like. Among these, 1,3-butadiene is preferable. These other monomers can be used alone or in combination of two or more. The content ratio of other monomer units in the polymer block (A) is preferably 15% by weight or less, more preferably 10% by weight or less, and further preferably 6% by weight or less. preferable.

  In the present invention, the polymer block (A) in the conjugated diene polymer chain is an isoprene monomer or isoprene, an aromatic vinyl monomer, and other units added as necessary in an inert solvent. The monomer mixture containing the monomer is formed by polymerizing with a polymerization initiator. The formed polymer block (A) has an active end.

  Used to polymerize isoprene monomers, or monomer mixtures containing isoprene and aromatic vinyl monomers, and other monomers added as needed to form polymer block (A) The inert solvent is not particularly limited as long as it is usually used in solution polymerization and does not inhibit the polymerization reaction. Specific examples thereof include, for example, chain aliphatic hydrocarbons such as butane, pentane, hexane, heptane, and 2-butene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and cyclohexene; aromatics such as benzene, toluene, and xylene. Group hydrocarbons; and the like. The amount of the inert solvent used is such that the monomer concentration is preferably 1 to 80% by weight, more preferably 10 to 50% by weight.

  The polymerization initiator used to form the polymer block (A) is a monomer comprising isoprene monomer, or isoprene and an aromatic vinyl monomer, and other monomers added as necessary. There is no particular limitation as long as the polymer mixture can be polymerized to give a polymer chain having an active end. As a specific example thereof, a polymerization initiator having an organic alkali metal compound, an organic alkaline earth metal compound, a lanthanum series metal compound, or the like as a main catalyst is preferably used. Examples of the organic alkali metal compound include organic monolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium and stilbenelithium; dilithiomethane, 1,4-dilithiobutane, 1,4 -Organic polyvalent lithium compounds such as dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, 1,3,5-tris (lithiomethyl) benzene; organic sodium compounds such as sodium naphthalene; organic such as potassium naphthalene And the like, and the like. Examples of the organic alkaline earth metal compound include di-n-butylmagnesium, di-n-hexylmagnesium, diethoxycalcium, disuccinate lucium, di-t-butoxystrontium, diethoxybarium, and diisopropoxy. Examples thereof include barium, diethyl mercaptobarium, di-t-butoxybarium, diphenoxybarium, diethylaminobarium, barium distearate, and diketylbarium. As a polymerization initiator having a lanthanum series metal compound as a main catalyst, for example, a lanthanum series metal comprising a lanthanum series metal such as lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, a carboxylic acid, and a phosphorus-containing organic acid. And a polymerization initiator composed of this salt and a cocatalyst such as an alkylaluminum compound, an organoaluminum hydride compound, and an organoaluminum halide compound. Among these polymerization initiators, it is preferable to use an organic monolithium compound, and it is more preferable to use n-butyllithium. The organic alkali metal compound may be used as an organic alkali metal amide compound by reacting with a secondary amine such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, hexamethyleneimine, heptamethyleneimine in advance. Good. These polymerization initiators can be used alone or in combination of two or more.

  The amount of the polymerization initiator used may be determined according to the target molecular weight, but is preferably 4 to 250 mmol, more preferably 6 to 200 mmol, particularly preferably 100 g of isoprene monomer or monomer mixture. It is in the range of 10 to 70 mmol.

  The polymerization temperature for polymerizing the isoprene monomer or monomer mixture is preferably in the range of −80 to + 150 ° C., more preferably 0 to 100 ° C., and still more preferably 20 to 90 ° C. As the polymerization mode, any mode such as batch mode or continuous mode can be adopted. Moreover, as a coupling | bonding mode, it can be set as various coupling | bonding modes, such as a block shape, a taper shape, and a random shape, for example.

  Moreover, in the manufacturing method of this invention, in order to adjust the vinyl bond content in the isoprene monomer unit in a polymer block (A), it is preferable to add a polar compound to an inert solvent in superposition | polymerization. Examples of polar compounds include ether compounds such as dibutyl ether, tetrahydrofuran, and 2,2-di (tetrahydrofuryl) propane; tertiary amines such as tetramethylethylenediamine; alkali metal alkoxides; phosphine compounds; Among these, ether compounds and tertiary amines are preferable, and among them, those capable of forming a chelate structure with the metal of the polymerization initiator are more preferable, and 2,2-di (tetrahydrofuryl) propane and tetramethylethylenediamine are more preferable. Particularly preferred. What is necessary is just to determine the usage-amount of a polar compound according to the vinyl bond content made into the objective, 0.01-30 mol is preferable with respect to 1 mol of polymerization initiators, and 0.05-10 mol is more preferable. When the amount of the polar compound used is within the above range, the vinyl bond content in the isoprene monomer unit can be easily adjusted, and problems due to the deactivation of the polymerization initiator hardly occur. Moreover, the vinyl bond content in an isoprene monomer unit can be increased by increasing the usage-amount of a polar compound within the said range.

  The vinyl bond content in the isoprene monomer unit in the polymer block (A) is preferably 5 to 90% by weight, and more preferably 5 to 80% by weight. By setting the vinyl bond content in the isoprene monomer unit within the above range, it is possible to further improve the low heat buildup and wet grip properties of the resulting rubber cross-linked product. In the present specification, the vinyl bond content in the isoprene monomer unit includes the isoprene monomer unit having a 1,2-structure and the 3,4-structure in the isoprene monomer unit. It shall refer to the proportion of the total amount of isoprene monomer units.

  The weight average molecular weight (Mw) of the polymer block (A) is preferably from 500 to 15,000, and preferably from 1,000 to 12,000 as a value in terms of polystyrene measured by gel permeation chromatography. Is more preferable and 1,500 to 10,000 is particularly preferable. When the weight average molecular weight of the polymer block (A) is within the above range, the low exothermic property and wet grip property of the resulting rubber cross-linked product can be further improved.

  The molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polymer block (A) is preferably 1.0 to 1.5, More preferably, it is 1.0 to 1.3. When the value (Mw / Mn) of the molecular weight distribution of the polymer block (A) is within the above range, the production of the conjugated diene rubber becomes easier.

[Polymer block (B)]
The polymer block (B) in the conjugated diene polymer chain according to the present invention comprises 50 to 100% by weight of 1,3-butadiene monomer units and aromatic vinyl monomer units in the polymer block (B). It is not particularly limited as long as it contains 0 to 50% by weight, and preferably contains 55 to 95% by weight of 1,3-butadiene monomer units and 5 to 45% by weight of aromatic vinyl monomer units, More preferably, it contains 55 to 90% by weight of 1,3-butadiene monomer units and 10 to 45% by weight of aromatic vinyl monomer units. When the content ratio of the 1,3-butadiene monomer unit and the aromatic vinyl monomer unit is within the above range, the production of the conjugated diene rubber becomes easier.

  As the aromatic vinyl monomer used for constituting the aromatic vinyl monomer unit contained in the polymer block (B), the aromatic vinyl monomer exemplified in the polymer block (A) described above is used. Styrene is preferred among these.

  The polymer block (B) is preferably composed of only a 1,3-butadiene monomer unit or only a 1,3-butadiene monomer unit and an aromatic vinyl monomer unit. In addition to the 1,3-butadiene monomer unit and the aromatic vinyl monomer unit, other monomer units may be further contained as desired within the range not impairing the essential characteristics of. As other monomers used for constituting other monomer units, the compounds exemplified in the polymer block (A) described above (excluding 1,3-butadiene) are similarly used. Can do. In the polymer block (B), isoprene can be used as another monomer. The content ratio of other monomer units in the polymer block (B) is preferably 50% by weight or less, more preferably 40% by weight or less, and further preferably 35% by weight or less. preferable.

  In the present invention, the polymer block (B) in the conjugated diene polymer chain includes the above-described polymer block (A) having an active terminal and 1,3-butadiene, or 1,3-butadiene and aromatic vinyl. By mixing the monomer mixture containing the monomer and continuing the polymerization reaction, the polymer block (A) is formed in a continuous manner. The formed polymer block (B) has an active end.

  Used to polymerize polymer block (A) and monomer mixture containing 1,3-butadiene or 1,3-butadiene and aromatic vinyl monomer to form polymer block (B) The inert solvent to be used is not particularly limited, and the same inert solvent used for the preparation of the polymer block (A) described above can be used.

  The amount of the polymer block (A) having an active terminal in forming the polymer block (B) may be determined according to the target molecular weight, but 1,3-butadiene or 1,3 -Preferably it is 0.1-5 mmol, More preferably, it is 0.15-2 mmol, More preferably, it is the range of 0.2-1.5 mmol per 100g of monomer mixtures containing a butadiene and an aromatic vinyl monomer.

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

  The polymerization temperature in polymerizing 1,3-butadiene or a monomer mixture containing 1,3-butadiene and an aromatic vinyl monomer is preferably −80 to + 150 ° C., more preferably 0 to 100 ° C. Preferably it is the range of 20-90 degreeC. As the polymerization mode, any mode such as batch mode or continuous mode can be adopted. When the polymer block (B) is used as a copolymer chain, a batch system is preferable because the randomness of the bonds can be easily controlled.

  When the polymer block (B) is used as a copolymer chain, the bonding mode of each monomer may be various bonding modes such as a block shape, a taper shape, and a random shape. Among these, a random shape is preferable. By making it random, the low heat build-up of the resulting rubber cross-linked product can be further improved. When the bonding mode of 1,3-butadiene and the aromatic vinyl monomer is random, in the polymerization system, the aromatic vinyl unit relative to the total amount of 1,3-butadiene and the aromatic vinyl monomer is used. 1,3-butadiene or 1,3-butadiene and an aromatic vinyl monomer may be continuously or intermittently supplied into the polymerization system for polymerization so that the ratio of the monomers does not become too high. preferable.

  In the present invention, in order to adjust the vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B), vinyl in the isoprene monomer unit in the polymer block (A) is used. Similarly to the adjustment of the bond content, it is preferable to add a polar compound to the inert solvent during the polymerization. However, at the time of preparing the polymer block (A), the polar compound in an amount sufficient to adjust the vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B) to the inert solvent Is added, a new polar compound may not be added. The specific example about the polar compound used in order to adjust vinyl bond content is the same as the polar compound used for preparation of the above-mentioned polymer block (A). The amount of the polar compound used may be determined according to the target vinyl bond content, and is preferably 0.01 to 100 mol, more preferably 0.1 to 30 mol, relative to 1 mol of the polymerization initiator. do it. When the amount of the polar compound used is within this range, the vinyl bond content in the 1,3-butadiene monomer unit can be easily adjusted, and problems due to the deactivation of the polymerization initiator hardly occur.

  The vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B) is preferably 10 to 90% by weight, more preferably 20 to 80% by weight, particularly preferably 25 to 70% by weight. is there. By setting the vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B) within the above range, the resulting rubber cross-linked product becomes more excellent in low heat buildup.

  In this way, a conjugated diene polymer chain having an active terminal and having a polymer block (A) and a polymer block (B) can be obtained. In the present invention, the conjugated diene polymer chain having an active terminal is composed of a polymer block (A) -polymer block (B) from the viewpoint of productivity, and the terminal of the polymer block (B). Is preferably an active terminal, but may have a plurality of polymer blocks (A) or may have other polymer blocks. For example, the polymer block (A) -polymer block (B) -polymer block (A) and polymer block (A) -polymer block (B) -having an active terminal such as a block consisting only of isoprene. A conjugated diene polymer chain may be mentioned. When forming a block consisting only of isoprene on the active terminal side of the conjugated diene polymer chain, the amount of isoprene used is the polymerization used in the initial polymerization reaction (polymerization reaction for forming the polymer block (A)). The amount is preferably 10 to 100 mol, more preferably 15 to 70 mol, and particularly preferably 20 to 35 mol with respect to 1 mol of the initiator.

  The weight ratio of the polymer block (A) to the polymer block (B) in the conjugated diene polymer chain having an active end obtained in the present invention (polymer block (A), plural polymer blocks (B) When present, the weight ratio based on the total weight of each of them is (weight of polymer block (A)) / (weight of polymer block (B)) and is 0.001 to 0.1. It is preferably 0.003 to 0.070, more preferably 0.005 to 0.05. By making the weight ratio of the polymer block (A) and the polymer block (B) within the above range, the resulting rubber cross-linked product can have a good balance between strength and low heat build-up. .

  The weight average molecular weight (Mw) of the conjugated diene polymer chain having an active end obtained in the present invention is a value in terms of polystyrene measured by gel permeation chromatography, and preferably 100,000 to 1,000,000. More preferably, it is 150,000-900,000, More preferably, it is 150,000-700,000. By setting the weight average molecular weight (Mw) of the conjugated diene polymer chain having an active end within the above range, the resulting rubber cross-linked product can have a good balance between strength and low exothermicity. .

  The molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the conjugated diene polymer chain having an active end is 1.0 to 3.0. Preferably, it is 1.0 to 2.5, more preferably 1.0 to 2.2. When the molecular weight distribution (Mw / Mn) of the conjugated diene polymer chain having an active end is within the above range, the production of the conjugated diene rubber is facilitated.

  In the conjugated diene polymer chain having an active end, the content ratio of the total monomer unit of the isoprene monomer unit and the 1,3-butadiene monomer unit and the aromatic vinyl monomer unit is the active end. In the conjugated diene polymer chain having a total of 50 to 100% by weight of monomer units of isoprene monomer units and 1,3-butadiene monomer units, and 0 to 50% by weight of aromatic vinyl monomer units The total monomer unit of isoprene monomer units and 1,3-butadiene monomer units is 55 to 95% by weight, and the aromatic vinyl monomer unit is 5 to 45% by weight. More preferably, the total monomer unit of isoprene monomer unit and 1,3-butadiene monomer unit is 55 to 90% by weight, and the aromatic vinyl monomer unit is 10 to 45% by weight. The vinyl bond content in the isoprene monomer unit and in the 1,3-butadiene monomer unit in the conjugated diene polymer chain having an active end is 1,3 in the polymer block (B) described above. -It is preferable that it exists in the same range as vinyl bond content in a butadiene monomer unit.

<Conjugated diene rubber>
In the method for producing a conjugated diene rubber according to the present invention, following the above-described step, the compound represented by the following general formula (1) is reacted with the active terminal of the conjugated diene polymer chain having the active terminal described above. By carrying out the process, a conjugated diene rubber is obtained.

In the general formula (1), R ^{1 to} R ³ are each an alkyl group having 1 to 4 carbon atoms, R ⁴ is a hydrocarbon group having 6 to 10 carbon atoms containing an aromatic ring, and R ⁵ Is an alkyl group having 1 to 6 carbon atoms, and n is an integer of 0 to 10.

  In the production method of the present invention, the conjugated diene polymer is modified by reacting the compound represented by the general formula (1) with the active end of the conjugated diene polymer chain having the active end described above. In addition, the affinity for fillers such as silica can be improved, thereby improving the shape stability, and the rubber cross-linked product obtained by using this has excellent low heat buildup and wet grip properties. Can be.

In the general formula (1), R ^{1 to} R ³ are each an alkyl group having 1 to 4 carbon atoms, preferably a methyl group or an ethyl group. R ^{1 to} R ³ may be the same group or different groups, but are all the same group from the viewpoint of facilitating the synthesis of the compound represented by the general formula (1). It is preferable.

In the general formula (1), R ⁴ is a C 6-10 hydrocarbon group containing an aromatic ring, preferably a phenyl group, a benzyl group, a phenethyl group, or a phenylpropyl group, more preferably Is a benzyl group. When R ⁴ in the general formula (1) is a 6 to 10 hydrocarbon group containing an aromatic ring, for example, a compound in which R ⁴ in the general formula (1) is a hydrocarbon group containing no aromatic ring is used. Compared with the case where the modified conjugated diene rubber is obtained, the affinity of the resulting modified conjugated diene rubber for fillers such as silica can be improved, thereby obtaining a rubber cross-linked product with lower heat generation and better wet grip. Can do.

In the general formula (1), R ⁵ is an alkyl group having 1 to 6 carbon atoms, preferably a methyl group, ethyl group or propyl group, more preferably a methyl group.

  Furthermore, in the said General formula (1), n is an integer of 0-10, Preferably it is an integer of 1-8, More preferably, it is an integer of 3-5.

  Specific examples of the compound represented by the general formula (1) include 3- (N-methyl-N-phenylamino) propyltrimethoxysilane and 3- (N-benzyl-N-methylamino) propyltrimethoxysilane. 3- (N-methyl-N-fetineramino) propyltrimethoxysilane, 3- (N-ethyl-N-benzyl) propyltrimethoxysilane, 3- (N-benzyl-N-methylamino) pentyltrimethoxy Examples include silane, 3- (N-benzyl-N-methylamino) propyltriethoxysilane, and among these, 3- (N-benzyl-N-methylamino) propyltrimethoxysilane is used. Particularly preferred. In addition, the compound represented by General formula (1) may be used individually by 1 type, and may be used in combination of 2 or more type.

  In the method for producing a conjugated diene rubber of the present invention, the amount of the compound represented by the general formula (1) is not particularly limited, but 1 mol of the active terminal of the conjugated diene polymer chain having an active terminal to be reacted. The amount of the compound represented by the general formula (1) with respect to is preferably 1 to 3 mol, more preferably 1 to 2 mol. By using the compound represented by the above general formula (1) in such an amount, the resulting conjugated diene rubber gives a rubber cross-linked product particularly excellent in low heat build-up. The number of active ends contained in the conjugated diene polymer having active ends obtained by the above-described process is usually determined by the amount of the polymerization initiator used for the polymerization. For example, the polymerization initiator When 1 mol is used, the number of active ends is also about 1 mol. Further, as described later, before reacting the compound represented by the general formula (1) with the active terminal, it is reacted with a tin halide, silicon halide, or a compound represented by the general formula (2). In this case, the amount of the “active end of the conjugated diene polymer having an active end” is intended to mean the amount of the active end remaining at the time when the compound represented by the general formula (1) is added. is there.

When the compound represented by the general formula (1) is added to an inert solvent in which a conjugated diene polymer having an active terminal is present, the active terminal of the conjugated diene polymer having an active terminal and the general formula The compound represented by (1) reacts. This reaction is usually performed by an alkoxy group of the compound represented by the general formula (1) (“R ¹ O—”, “R ² O bonded to a silicon atom represented by“ Si ”in the formula (1)”). Any one of the groups represented by — ”and“ R ³ O— ”is eliminated from the compound represented by the general formula (1), and reacts with the active terminal of the conjugated diene polymer to produce a conjugated diene system. It proceeds in a form in which a bond is formed between the polymer chain of the polymer and the bond in the silicon atom represented by “Si” in the general formula (1).

  The method of reacting the compound represented by the general formula (1) with the conjugated diene polymer chain having an active end is not particularly limited, but a method of mixing them in a solvent in which each of them can be dissolved, etc. Is mentioned. As the solvent used in this case, those exemplified as the inert solvent used in the polymerization for forming the polymer block (A) and the polymer block (B) described above can be used. In this case, a method of adding the compound represented by the general formula (1) to the polymerization solution used for the polymerization for obtaining a conjugated diene polymer chain having an active end is simple and preferable. In this case, the compound represented by the general formula (1) is preferably dissolved in an inert solvent and added to the polymerization system, and the solution concentration is in the range of 1 to 50% by weight. It is preferable. Although reaction temperature is not specifically limited, Usually, it is 0-120 degreeC, Reaction time is also not specifically limited, Usually, it is 1 minute-1 hour.

  The timing of adding the compound represented by the general formula (1) to the solution containing the conjugated diene polymer chain having an active end is not particularly limited, but the polymerization reaction in the conjugated diene polymer chain having an active end Is not completed, and the solution containing a conjugated diene polymer chain having an active end also contains a monomer, more specifically, a conjugated diene polymer chain having an active end It is desirable to add the compound represented by the above general formula (1) to this solution in a state where the solution to be contained contains 100 ppm or more, more preferably 300 to 50,000 ppm of monomer. By adding the compound represented by the general formula (1) in this manner, side reactions between the conjugated diene polymer chain having an active terminal and impurities contained in the polymerization system are suppressed, and the reaction is performed. Can be controlled well.

Moreover, in the manufacturing method of this invention, after obtaining the conjugated diene type polymer chain which has a polymer block (A) and a polymer block (B) and which has an active terminal, the conjugated diene polymer which has an active terminal A conjugated diene system having an active end in a state before the chain is reacted with the compound represented by the general formula (1) or after the chain is reacted with the compound represented by the general formula (1) When the polymer chain remains, a part of the active end of the conjugated diene polymer chain having an active end is represented by tin halide, silicon halide, or the following general formula (2). It is preferable to further comprise a step of reacting with a compound. In addition, tin halide, silicon halide, and the compound represented by the following general formula (2) act as a coupling agent by reacting with the active end of a conjugated diene polymer chain having an active end. Thereby, a branched structure (preferably a branched structure having three or more branches) can be introduced into the resulting conjugated diene rubber, and the shape stability of the conjugated diene rubber can be further improved.

In the general formula (2), R ⁶ represents a hydrocarbon group which may have a substituent, X ¹ represents a halogen group, and M represents a silicon atom or a tin atom.

  Examples of tin halides include tin tetrachloride and triphenylmonochlorotin, with tin tetrachloride being preferred. Examples of the silicon halide include silicon tetrachloride, hexachlorodisilane, triphenoxychlorosilane, methyltriphenoxysilane, and diphenoxydichlorosilane, with silicon tetrachloride being preferred.

In the general formula (2), R ⁶ represents a hydrocarbon group which may have a substituent, and the hydrocarbon group that can be R ⁶ is not particularly limited, but includes a methylene group, 1,2- Ethylene group, 1,3-propylene group, 1,4-butylene group, 1,5-pentylene group, 1,6-hexylene group, 4-methyl-1,5-pentylene group, 2,3-dimethyl-1, 4-butylene group etc. are mentioned. Among these, 1,2-ethylene group and 1,6-hexylene group are preferable. In addition, the halogen group that can be X ² is not particularly limited, and examples thereof include a fluoro group, a chloro group, a bromo group, and an iodo group, and among these, a chloro group is preferable. Furthermore, although M is a silicon atom or a tin atom, it is preferably a silicon atom.

  Specific examples of the compound represented by the general formula (2) include bis (trichlorosilyl) methane, 1,2-bis (trichlorosilyl) ethane, 1,3-bis (trichlorosilyl) propane, Examples include 4-bis (trichlorosilyl) butane, 1,5-bis (trichlorosilyl) pentane, and 1,6-bis (trichlorosilyl) hexane.

  In the method for producing a conjugated diene rubber of the present invention, the amount of tin halide, silicon halide, or the compound represented by the general formula (2) is not particularly limited, but the conjugated diene having an active terminal to be reacted is used. The amount per 1 mol of the active terminal of the polymer chain is preferably 0.001 to 0.2 mol, more preferably 0.005 to 0.1 mol, and 0.01 to 0.05 mol. It is particularly preferred that By using the tin halide, the silicon halide, or the compound represented by the general formula (2) in such an amount, the shape stability of the resulting conjugated diene rubber can be further improved.

  A method of reacting a part of the chain end of the conjugated diene polymer having an active end with tin halide, silicon halide, or the compound represented by the general formula (2) is not particularly limited. The method of mixing in the solvent which can melt | dissolve each is mentioned. As the solvent used in this case, those exemplified as the inert solvent used in the polymerization for forming the polymer block (A) and the polymer block (B) described above can be used. In this case, tin halide, silicon halide, or a compound represented by the above general formula (2) is added to a polymerization solution used for polymerization for obtaining a conjugated diene polymer chain having an active end. The method of adding is simple and preferable. In this case, tin halide, silicon halide or the compound represented by the general formula (2) is preferably dissolved in an inert solvent and added to the polymerization system, and the solution concentration is 1 to 50% by weight is preferable. Although reaction temperature is not specifically limited, Usually, it is 0-120 degreeC, Reaction time is also not specifically limited, Usually, it is 1 minute-1 hour.

  Further, the timing of adding tin halide, silicon halide, or a compound represented by the above general formula (2) to a solution containing a conjugated diene polymer chain having an active end is also the above general formula (1). As in the case of the compound represented by formula (1), the polymerization reaction in the conjugated diene polymer chain having an active end is not completed, and the solution containing the conjugated diene polymer chain having an active end is It is desirable to add in the state which also contains.

  The coupling rate of the conjugated diene rubber of the present invention is not particularly limited, but is preferably 10% by weight or more, more preferably 15% by weight or more, particularly preferably 20% by weight or more, and preferably 80% by weight. Hereinafter, it is more preferably 75% by weight or less, particularly preferably 70% by weight or less. If the coupling rate is too low, the mechanical strength of the crosslinked product obtained from the conjugated diene rubber may be insufficient, and if the coupling rate is too high, the crosslinked product obtained from the conjugated diene rubber. There is a risk that the wear resistance of the resin becomes insufficient. In addition, the coupling rate is determined before the reaction with the compound represented by the above general formula (1) and, if desired, the tin halide, silicon halide, or the compound represented by the above general formula (2). This is the weight fraction of the polymer molecule having a molecular weight of 1.8 times or more of the peak top molecular weight of the conjugated diene polymer chain having an active end with respect to the total amount of the finally obtained conjugated diene rubber. The molecular weight is determined as a molecular weight in terms of polystyrene by gel permeation chromatography.

  At the active end of the conjugated diene polymer chain, the compound represented by the above general formula (1) and, if desired, tin halide, silicon halide or the compound represented by the above general formula (2) After the reaction, it is preferable to deactivate the unreacted active terminal by adding a polymerization terminator such as alcohol such as methanol and isopropanol or water.

  After deactivating the active end of the conjugated diene polymer chain, polymerize anti-aging agents such as phenol stabilizers, phosphorus stabilizers, sulfur stabilizers, crumbs, and scale inhibitors as desired. After adding to the solution, the polymerization solvent is separated from the polymerization solution by direct drying or steam stripping, and the conjugated diene rubber obtained by the production method of the present invention is recovered. Before separating the polymerization solvent from the polymerization solution, an extending oil may be mixed into the polymerization solution and the conjugated diene rubber may be recovered as an oil-extended rubber.

  Examples of the extending oil used when recovering the conjugated diene rubber as an oil-extended rubber include paraffinic, aromatic and naphthenic petroleum softeners, plant softeners, and fatty acids. When using a petroleum softener, it is preferable that the content of polycyclic aromatics extracted by the method of IP346 (the inspection method of THE INSTITUTE PETROLEUM in the UK) is less than 3%. When using the extender oil, the amount used is preferably 5 to 100 parts by weight, more preferably 10 to 60 parts by weight, and still more preferably 20 to 50 parts by weight with respect to 100 parts by weight of the conjugated diene rubber. .

  The weight average molecular weight (Mw) of the conjugated diene rubber obtained by the production method of the present invention is a value measured by gel permeation chromatography in terms of polystyrene, preferably 100,000 to 3,000,000, more preferably 150,000 to 2,000,000, particularly preferably 200,000 to 1,5,000,000. By making the weight average molecular weight of the conjugated diene rubber within the above range, it becomes easy to add silica to the conjugated diene rubber, the processability of the rubber composition is excellent, and the resulting rubber cross-linked product has low heat generation. The sex can be further improved.

  The molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the conjugated diene rubber obtained by the production method of the present invention is 1.1 to 3.0. It is preferably 1.2 to 2.5, more preferably 1.2 to 2.2. By setting the molecular weight distribution (Mw / Mn) of the conjugated diene rubber within the above range, the low exothermic property of the resulting rubber cross-linked product can be further improved.

The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the conjugated diene rubber obtained by the production method of the present invention is preferably 20 to 100, more preferably 30 to 90, and particularly preferably 35 to 80. When the conjugated diene rubber is an oil-extended rubber, the Mooney viscosity of the oil-extended rubber is preferably in the above range.

  Thus, the conjugated diene rubber obtained by the production method of the present invention is excellent in shape stability, and is suitable for various uses after adding compounding agents such as a filler and a crosslinking agent. Can be used. In particular, when silica is blended as a filler, it is possible to provide a rubber composition that is suitably used to obtain a crosslinked rubber product having low heat build-up and excellent wet grip properties.

<Rubber composition>
The rubber composition of the present invention is a composition comprising 10 to 200 parts by weight of silica with respect to 100 parts by weight of a rubber component containing the conjugated diene rubber obtained by the production method of the present invention described above.

Examples of the silica used in the present invention include dry method white carbon, wet method white carbon, colloidal silica, and precipitated silica. Among these, wet method white carbon mainly containing hydrous silicic acid is preferable. Alternatively, a carbon-silica dual phase filler in which silica is supported on the carbon black surface may be used. These silicas can be used alone or in combination of two or more. Is (measured by the BET method according to ASTM D3037-81) nitrogen adsorption specific surface area of silica used is preferably 50 to 300 m ² / g, more preferably 80~220m ² / g, particularly preferably 100~170m ² / g. Moreover, it is preferable that the pH of a silica is pH 5-10.

  The compounding quantity of the silica in the rubber composition of this invention is 10-200 weight part with respect to 100 weight part of rubber components in a rubber composition, Preferably it is 30-150 weight part, More preferably, it is 50-100 weight. Part. By making the compounding quantity of silica into the above range, the processability of the rubber composition becomes excellent, and the wet grip property of the obtained rubber cross-linked product can be further improved.

  The rubber composition of the present invention may further contain a silane coupling agent from the viewpoint of further improving the low heat buildup. Examples of the silane coupling agent include vinyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, 3-octathio- 1-propyl-triethoxysilane, bis (3- (triethoxysilyl) propyl) disulfide, bis (3- (triethoxysilyl) propyl) tetrasulfide, γ-trimethoxysilylpropyldimethylthiocarbamyl tetrasulfide, and γ -Trimethoxysilylpropyl benzothiazyl tetrasulfide etc. can be mentioned. These silane coupling agents can be used alone or in combination of two or more. The blending amount of the silane coupling agent is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight with respect to 100 parts by weight of silica.

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

  The method of adding silica to the rubber component containing the modified conjugated diene rubber of the present invention is not particularly limited, and a method of adding and kneading a solid rubber component (dry kneading method) or a conjugated diene system A method (wet kneading method) that is added to a solution containing rubber and coagulated and dried can be applied.

  Moreover, it is preferable that the rubber composition of the present invention further contains a crosslinking agent. Examples of the crosslinking agent include sulfur, sulfur halides, organic peroxides, quinonedioximes, organic polyvalent amine compounds, and alkylphenol resins having a methylol group. Among these, sulfur is preferably used. The amount of the crosslinking agent is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight with respect to 100 parts by weight of the rubber component in the rubber composition. It is.

  Further, in addition to the above components, the rubber composition of the present invention includes a crosslinking accelerator, a crosslinking activator, an anti-aging agent, a filler (excluding silica and carbon black), an activator, and a process oil in accordance with conventional methods. , Plasticizers, lubricants, tackifiers and the like can be blended in the required amounts.

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

  Examples of the crosslinking activator include higher fatty acids such as stearic acid; zinc oxide. These crosslinking activators are used alone or in combination of two or more. The amount of the crosslinking activator is preferably 0.05 to 20 parts by weight, particularly preferably 0.5 to 15 parts by weight with respect to 100 parts by weight of the rubber component in the rubber composition.

  Moreover, you may mix | blend rubbers other than the conjugated diene type rubber | gum obtained by the manufacturing method of this invention mentioned above with the rubber composition of this invention. Examples of other rubbers include natural rubber, polyisoprene rubber, emulsion polymerization styrene-butadiene copolymer rubber, solution polymerization styrene-butadiene copolymer rubber, and polybutadiene rubber (high cis-BR and low cis BR may be used. Further, it may be a polybutadiene rubber containing crystal fibers made of 1,2-polybutadiene polymer), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, acrylonitrile-butadiene. Among copolymer rubbers, acrylonitrile-styrene-butadiene copolymer rubbers and the like, it refers to those other than the conjugated diene rubbers obtained by the production method of the present invention described above. Among these, natural rubber, polyisoprene rubber, polybutadiene rubber, and solution-polymerized styrene-butadiene copolymer rubber are preferable. These rubbers can be used alone or in combination of two or more.

  In the rubber composition of the present invention, the conjugated diene rubber obtained by the production method of the present invention preferably accounts for 10 to 100% by weight, preferably 50 to 100% by weight of the rubber component in the rubber composition. Particularly preferred. By including the conjugated diene rubber of the present invention in the rubber component at such a ratio, a crosslinked rubber product having improved wet grip properties can be obtained.

  In order to obtain the rubber composition of the present invention, each component may be kneaded according to a conventional method. For example, a component excluding a thermally unstable component such as a crosslinking agent or a crosslinking accelerator and a conjugated diene rubber are kneaded. Thereafter, the kneaded product can be mixed with a thermally unstable component such as a crosslinking agent or a crosslinking accelerator to obtain a desired composition. The kneading temperature of the component excluding the thermally unstable component and the conjugated diene rubber is preferably 80 to 200 ° C., more preferably 120 to 180 ° C., and the kneading time is preferably 30 seconds to 30 minutes. is there. The kneaded product and the thermally unstable component are usually mixed after cooling to 100 ° C. or lower, preferably 80 ° C. or lower.

  The rubber composition of the present invention can be used, for example, as a tire after being crosslinked, or as a rubber for resin reinforcement such as impact-resistant polystyrene.

<Rubber cross-linked product>
The rubber cross-linked product of the present invention is obtained by cross-linking the rubber composition of the present invention described above.
The rubber cross-linked product of the present invention uses the rubber composition of the present invention, for example, is molded by a molding machine corresponding to a desired shape, for example, an extruder, an injection molding machine, a compressor, a roll, and heated. Can be produced by carrying out a crosslinking reaction and fixing the shape as a crosslinked product. In this case, crosslinking may be performed after molding in advance, or crosslinking may be performed simultaneously with molding. The molding temperature is usually 10 to 200 ° C, preferably 25 to 120 ° C. The crosslinking temperature is usually 100 to 200 ° C, preferably 130 to 190 ° C, and the crosslinking time is usually 1 minute to 24 hours, preferably 2 minutes to 12 hours, particularly preferably 3 minutes to 6 hours. .

  Further, depending on the shape and size of the rubber cross-linked product, even if the surface is cross-linked, it may not be sufficiently cross-linked to the inside. Therefore, secondary cross-linking may be performed by heating.

  As a heating method, a general method used for crosslinking of rubber such as press heating, steam heating, oven heating, and hot air heating may be appropriately selected.

  The rubber cross-linked product of the present invention thus obtained is obtained by using the conjugated diene rubber obtained by the production method of the present invention described above, and therefore has excellent low heat buildup and wet grip properties. . The rubber cross-linked product of the present invention makes use of such characteristics, and for example, in tires, materials for tire parts such as cap treads, base treads, carcass, sidewalls and bead parts; hoses, belts, mats, It can be used in various applications such as vibration rubber and other various industrial article materials; resin impact resistance improvers; resin film buffers; shoe soles; rubber shoes; golf balls; In particular, the rubber cross-linked product of the present invention can be suitably used in various parts of a tire such as a tread, a carcass, a sidewall, and a bead part in various tires such as an all-season tire, a high-performance tire, and a studless tire, In particular, since it is excellent in low heat generation property, it can be particularly suitably used as a tread for a fuel-efficient tire.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples. In the following, “part” and “%” are based on weight unless otherwise specified. Moreover, the test and evaluation followed the following.

[Weight average molecular weight, molecular weight distribution, coupling rate]
The weight average molecular weight (Mw), molecular weight distribution (Mw / Mn), and coupling rate were determined based on the chart obtained by obtaining a chart based on the molecular weight in terms of polystyrene by gel permeation chromatography. The specific measurement conditions for gel permeation chromatography were as follows.
Measuring instrument: High-performance liquid chromatograph (trade name “HLC-8220” manufactured by Tosoh Corporation)
Column: Tosoh Corporation, product name "GMH-HR-H" was connected in series.
Detector: Differential refractometer Eluent: Tetrahydrofuran Column temperature: 40 ° C
Regarding the coupling rate, in the elution curve obtained by gel permeation chromatography under the above conditions, the peak top molecular weight is 1.8 times or more the peak top molecular weight indicated by the peak with the smallest molecular weight relative to the total elution area. The area ratio of the peak portion was defined as the value of the coupling rate of the conjugated diene polymer chain.

[Aromatic vinyl monomer unit content, vinyl bond content]
The aromatic vinyl monomer unit content and the vinyl bond amount were measured by ¹ H-NMR.

[Shape stability of conjugated diene rubber]
The conjugated diene polymer was formed into a sheet having a thickness of 2 mm, and then punched out into a dumbbell shape No. 8 defined in JIS K6251. Two marked lines were drawn at the center of the dumbbell-shaped specimen so that the distance between the marked lines was 10 mm. Next, one side of the gripping part of the test piece is fixed and suspended from above, left at a temperature of 23 ° C. and a humidity of 50% for 96 hours, and the distance between marked lines after standing is determined, and this is a value of shape stability. It was. The shape stability value is indicated by an index with the measured value of Comparative Example 1 being 100. The smaller this index, the better the shape stability.

[Low heat build-up of rubber cross-linked product]
For low heat generation, tan δ at 60 ° C. is measured under the conditions of dynamic strain 2.5% and 10 Hz, using ARES manufactured by Rheometrics Co., Ltd., with a test piece having a length of 50 mm, a width of 12.7 mm, and a thickness of 2 mm. It was evaluated by. The value of tan δ is indicated by an index with the measured value of Comparative Example 1 being 100. The smaller this index, the better the low heat buildup.

[Wet grip properties of rubber cross-linked products]
For the wet grip property, a test piece having a length of 50 mm, a width of 12.7 mm, and a thickness of 2 mm was used. Evaluation was made by measuring. The value of tan δ is indicated by an index with the measured value of Comparative Example 1 being 100. The larger this index, the better the wet grip.

[Example 1]
To a 100 ml ampule bottle purged with nitrogen, 49.6 g of cyclohexane and 0.56 mmol of tetramethylethylenediamine were added, and 5.6 mmol of n-butyllithium was further added. Next, 11.48 g of isoprene and 0.93 g of styrene were slowly added and reacted in an ampoule bottle at 50 ° C. for 120 minutes to obtain initiator 1. This initiator 1 (corresponding to polymer block (A)) has a weight average molecular weight (Mw) of 3500, a molecular weight distribution (Mw / Mn) of 1.10, and an aromatic vinyl monomer unit content of 7.5%. The isoprene unit content was 92.5%, and the vinyl bond content was 7.9%.

Next, in an autoclave equipped with a stirrer, 4000 g of cyclohexane, 8.1 mmol of tetramethylethylenediamine, 440.4 g of 1,3-butadiene, and 159.6 g of styrene were charged in a nitrogen atmosphere, and then the initiator 1 obtained above. And the polymerization was started at 40 ° C. After 10 minutes from the start of polymerization, 350.0 g of 1,3-butadiene and 50.0 g of styrene were continuously added over 60 minutes. The maximum temperature during the polymerization reaction was 60 ° C. After completion of the continuous addition, the polymerization reaction was continued for another 20 minutes, and after confirming that the polymerization conversion was in the range of 95% to 100%, 0.16 mmol of 1,6-bis (trichlorosilyl) hexane was added. And allowed to react for 10 minutes. Next, 8.06 mmol of 3- (benzylmethylamino) propyltrimethoxysilane (a compound represented by the following formula (3)) was added and reacted for 30 minutes. Thereafter, as a polymerization terminator, an amount of methanol corresponding to twice the mole of n-butyllithium used was added to obtain a solution containing a conjugated diene rubber. Irganox 1520L (manufactured by Ciba Specialty Chemicals) as an anti-aging agent was added to this solution in an amount of 0.15 part per 100 parts of conjugated diene rubber, and the solvent was removed by steam stripping. For 24 hours to obtain a solid conjugated diene rubber. The obtained conjugated diene rubber of Example 1 had a weight average molecular weight (Mw) of 510000, a molecular weight distribution (Mw / Mn) of 1.30, and a coupling rate of 52.3%. Further, when the conjugated diene rubber of Example 1 obtained was evaluated for shape stability according to the above method, the shape stability index value (value when the result of Comparative Example 1 was set to 100). Hereinafter, the same applies to each Example and Comparative Example).

[Example 2]
In the same manner as in Example 1 except that 0.16 mmol of 1,2-bis (trichlorosilyl) ethane was used instead of 0.16 mmol of 1,6-bis (trichlorosilyl) hexane, A conjugated diene rubber was obtained. The obtained conjugated diene rubber of Example 2 had a weight average molecular weight (Mw) of 525,000, a molecular weight distribution (Mw / Mn) of 1.29, and a coupling rate of 53.3%. Moreover, when the conjugated diene rubber of Example 2 obtained was evaluated for shape stability according to the above method, the shape stability index value was 37.

Example 3
A solid conjugated diene rubber was obtained in the same manner as in Example 1 except that 0.16 mmol of tin tetrachloride was used instead of 0.16 mmol of 1,6-bis (trichlorosilyl) hexane. . The obtained conjugated diene rubber of Example 3 had a weight average molecular weight (Mw) of 496,000, a molecular weight distribution (Mw / Mn) of 1.29, and a coupling rate of 50.0%. Further, when the obtained conjugated diene rubber of Example 3 was evaluated for shape stability in accordance with the above method, the shape stability index value was 45.

Example 4
A solid conjugated diene rubber was obtained in the same manner as in Example 1 except that 1,6-bis (trichlorosilyl) hexane was not added. The resulting conjugated diene rubber of Example 4 had a weight average molecular weight (Mw) of 468,000, a molecular weight distribution (Mw / Mn) of 1.28, and a coupling rate of 47.5%. Moreover, when the conjugated diene rubber of Example 4 obtained was evaluated for shape stability according to the above method, the shape stability index value was 79.

[Comparative Example 1]
Epoxylated polyorgano represented by the following formula (4) instead of adding 1,6-bis (trichlorosilyl) hexane and replacing with 8.06 mmol of 3- (benzylmethylamino) propyltrimethoxysilane Example 1 except that siloxane was added in the form of a 20% by weight concentration xylene solution so that the epoxy group content was equivalent to 0.33 mol of n-butyllithium used. In the same manner as above, a solid conjugated diene rubber was obtained. The resulting conjugated diene rubber of Comparative Example 1 had a weight average molecular weight (Mw) of 533,000, a molecular weight distribution (Mw / Mn) of 1.35, and a coupling rate of 51.1%. Further, when the conjugated diene rubber of Comparative Example 1 obtained was evaluated for shape stability according to the above method, the shape stability index value was 100.

[Comparative Example 2]
In a nitrogen atmosphere, 800 g of cyclohexane, 94.8 g of 1,3-butadiene, 25.2 g of styrene, and 0.164 g of tetramethylethylenediamine were charged into an autoclave, and then 0.86 mmol of n-butyllithium was added at 60 ° C. Polymerization was started. The polymerization reaction was continued for 60 minutes, and after confirming that the polymerization conversion was in the range of 95% to 100%, 0.026 mmol of tin tetrachloride was added and allowed to react for 10 minutes. Next, after adding 1.3 mmol of 3- (benzylmethylamino) propyltrimethoxysilane and reacting for 30 minutes, 1.7 mmol of methanol was added as a polymerization terminator, and a solution containing a conjugated diene rubber was added. Obtained. Then, 2,4-bis [(octylthio) methyl] -o-cresol (trade name “Irganox 1520” manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.15 as an anti-aging agent with respect to 100 parts of the obtained rubber component. After adding a portion to the solution, the solvent was removed by steam stripping, followed by vacuum drying at 60 ° C. for 24 hours to obtain a solid conjugated diene rubber. The resulting conjugated diene rubber of Comparative Example 2 had a weight average molecular weight (Mw) of 450,000, a molecular weight distribution (Mw / Mn) of 1.27, and a coupling rate of 46.6%. Further, when the obtained conjugated diene rubber of Comparative Example 2 was evaluated for shape stability according to the above method, the shape stability index value was 125.

[Production and evaluation of rubber composition and rubber cross-linked product]
In a Brabender type mixer with a capacity of 250 ml, 100 parts of the conjugated diene rubber of Example 1 was masticated for 30 seconds, followed by 50 parts of silica (trade name “Zeosil 1115MP” manufactured by Rhodia), process oil (Shin Nippon Oil Co. Product, 20 parts by trade name “Aromax T-DAE”, and 6.0 parts silane coupling agent: bis (3- (triethoxysilyl) propyl) tetrasulfide (trade name “Si69”, manufactured by Degussa) The mixture was added and kneaded for 1.5 minutes with 110 ° C. as the starting temperature, and then 25 parts of silica (trade name “Zeosil 1115MP” manufactured by Rhodia), 3 parts of zinc oxide, 2 parts of stearic acid, and anti-aging agent: N-phenyl- 2 parts of N ′-(1,3-dimethylbutyl) -p-phenylenediamine (made by Ouchi Shinsei Co., Ltd., trade name “NOCRACK 6C”) And pressurized and kneaded further 2.5 minutes and drained a kneaded material from the mixer. The temperature of the kneaded product at the end of kneading was 150 ° C. After the kneaded product was cooled to room temperature, it was kneaded again in a Brabender type mixer at 110 ° C. for 2 minutes, and then the kneaded product was discharged from the mixer. Next, with an open roll at 50 ° C., the obtained kneaded product was mixed with 1.40 parts of sulfur, a crosslinking accelerator: N-tert-butyl-2-benzothiazolylsulfenamide (trade name “Noxeller NS-P”, After adding 1.2 parts of Ouchi Shinsei Chemical Co., Ltd.) and 1.2 parts of diphenylguanidine (trade name “Noxeller D”, Ouchi Shinsei Chemical Co., Ltd.) and kneading them, a sheet-like rubber composition The thing was taken out. This rubber composition was press-crosslinked at 160 ° C. for 20 minutes to produce a rubber cross-linked test piece. The test piece was evaluated for low heat build-up and wet grip. For the conjugated diene rubbers of Examples 2 to 4, Comparative Example 1 and Comparative Example 2, test pieces of rubber cross-linked products were prepared in the same manner, and low heat build-up and wet grip properties were obtained for these test pieces. Was evaluated. Table 1 summarizes these results.

  The conjugated diene polymers (Examples 1 to 4) obtained by the method for producing a conjugated diene polymer of the present invention are excellent in shape stability. As can be seen from Table 1, the conjugated diene polymers of the present invention are used. The rubber cross-linked product obtained by using the conjugated diene polymer obtained by the polymer production method was obtained by using the conjugated diene polymer (Comparative Example 1 and Comparative Example 2) terminal-modified by a conventional method. Compared to rubber cross-linked products, low heat build-up and wet grip properties are excellent.

Claims (7)

In an inert solvent, an isoprene monomer or a monomer mixture containing isoprene and an aromatic vinyl monomer is polymerized with a polymerization initiator to obtain 80 to 100% by weight of isoprene monomer units and an aromatic vinyl monomer. Forming a polymer block (A) having an active end containing 0 to 20% by weight of a monomer unit;
The polymer block (A) having the active terminal and 1,3-butadiene, or a monomer mixture containing 1,3-butadiene and an aromatic vinyl monomer are mixed to continue the polymerization reaction, A polymer block (B) having an active terminal containing 50 to 100% by weight of 1,3-butadiene monomer units and 0 to 50% by weight of aromatic vinyl monomer units is combined with the polymer block (A). A step of obtaining a conjugated diene polymer chain having an active end having the polymer block (A) and the polymer block (B), and
A process of reacting a compound represented by the following general formula (1) with the active terminal of the conjugated diene polymer chain having the active terminal.

(In the general formula ^(1), R 1 ~R ³ are each an alkyl group having 1 to 4 carbon atoms, ^{R 4} is a hydrocarbon group having 6 to 10 carbon atoms containing an aromatic ring, R ⁵ is an alkyl group having 1 to 6 carbon atoms, and n is an integer of 0 to 10.) After the step of obtaining a conjugated diene polymer chain having an active end, having the polymer block (A) and the polymer block (B), a part of the active end is tin halide, silicon halide, or The method for producing a conjugated diene rubber according to claim 1, further comprising a step of reacting with the compound represented by the general formula (2).

(In the general formula (2), R ⁶ represents a hydrocarbon group that may have a substituent, X ¹ represents a halogen group, and M represents a silicon atom or a tin atom.)   A conjugated diene rubber obtained by the production method according to claim 1.   A rubber composition comprising 10 to 200 parts by weight of silica with respect to 100 parts by weight of a rubber component containing the conjugated diene rubber according to claim 3.   The rubber composition according to claim 4, further comprising a cross-linking agent.   A crosslinked rubber product obtained by crosslinking the rubber composition according to claim 5.   A tire comprising the rubber cross-linked product according to claim 6.