Terminal-modified diene polymer and method for producing the same

Abstract

To provide a terminally modified diene-based polymer having excellent mechanical properties, and a method for producing the same.SOLUTION: The terminally modified diene-based polymer is obtained such that a diene-based polymer terminated with ketone or aldehyde groups is reacted with a heterocyclic compound that is a nitrogen-containing unsaturated 5- or 6-membered ring compound having a primary amine.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a terminally modified diene polymer and a method for producing the same.

Background Art

[0002] Various means for enhancing the physical properties of rubber polymers have been conventionally studied. For example, Patent Document 1 describes a method for producing a modified polymer by reacting a polymer having at least one carbon-carbon double bond with a compound represented by the formula (M), wherein when reacting the polymer with the compound, a manganese catalyst having an acetylacetonate ligand is used. However, since the addition reaction of a phosphate group consumes the double bond, there is a risk of a decrease in crosslink density.

[0003] Also, Patent Document 2 describes that by introducing carboxy ions and having them form ionic bonds, the mechanical strength is significantly improved. However, since the rubber contains ionic functional groups, it becomes water-absorbent. Since the strength decreases due to water absorption, there is a problem that it is difficult to control the amount of functional group introduced.

[0004] Also, Patent Document 3 describes that by introducing host and guest molecules into the polymer chain, a crosslinked structure is created by their host-guest interaction and the mechanical strength is improved. However, cyclodextrin used as the host molecule is expensive and has low compatibility with rubber, so there is a problem that it aggregates in the rubber.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] In view of the above points, an object of the present invention is to provide a terminally modified diene-based polymer having excellent mechanical properties and a method for producing the same.

MEANS FOR SOLVING THE PROBLEMS

[0007] The terminally modified diene-based polymer according to the present invention is obtained by reacting a diene-based polymer having a ketone group or an aldehyde group at a terminal with a heterocyclic compound which is a nitrogen-containing unsaturated 5-membered or 6-membered ring compound having a primary amine in order to solve the above problems.

[0008] The heterocyclic compound can be at least one of the compounds represented by any of the following general formulas (1) to (4).

CHEMICAL

[0009] The weight average molecular weight can be 400,000 to 2,600,000.

[0010]

[0011] The method for producing a terminally modified diene-based polymer according to the present invention includes an oxidative decomposition step of adding an oxidizing agent to a diene-based polymer to oxidatively cleave a carbon-carbon double bond to obtain an oxidatively decomposed diene-based polymer, and a terminal modification step of reacting the obtained oxidatively decomposed diene-based polymer with a heterocyclic compound which is a nitrogen-containing unsaturated 5-membered or 6-membered ring compound having a primary amine.​

[0012] The above heterocyclic compound can be at least one of the compounds represented by any of the following general formulas (1) to (4).

Chemical formula

[0013] The addition amount of the above heterocyclic compound can be 0.01 to 0.5 mol per 1 kg of the above diene-based polymer.

[0014] Rubber latex can be used as the above diene-based polymer.

Advantages of the Invention

[0015] According to the present invention, it is possible to provide a terminally modified diene-based polymer having excellent mechanical properties and a method for producing the same.

Modes for Carrying Out the Invention

[0016] Hereinafter, matters related to the implementation of the present invention will be described in detail.

[0017] The terminally modified diene-based polymer according to the present embodiment is obtained by reacting a diene-based polymer having a ketone group or an aldehyde group at the terminal with a heterocyclic compound which is a nitrogen-containing unsaturated 5-membered or 6-membered ring compound having a primary amine.

[0018] The above heterocyclic compound is not particularly limited, but it is preferably at least one of the compounds represented by any of the following general formulas (1) to (4).

Chemical formula

[0019] The terminal-modified diene polymer preferably has at least one of the structures represented by general formulas (1a) to (1d), (2a) to (2d), (3a) to (3d), and (4a) to (4d) at the terminal. However, in the formula, R1 to R 10 represents hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and they may be the same or different from each other.

[0020] [Chemical formula]

[0021] [Chemical formula]

[0022] [Chemical formula]

[0023] [Chemical formula]

[0024] The method for producing the terminal-modified diene polymer according to this embodiment includes an oxidative decomposition step of adding an oxidizing agent to a diene polymer to oxidatively cleave a carbon-carbon double bond to obtain an oxidatively decomposed diene polymer, and a terminal modification step of adding and reacting a heterocyclic compound, which is a nitrogen-containing unsaturated 5-membered or 6-membered ring compound having a primary amine, to the obtained oxidatively decomposed diene polymer. The oxidative decomposition step and the terminal modification step may be carried out in one pot. Here, "one pot" means continuous synthesis in one container.

[0025] The above-mentioned heterocyclic compound is not particularly limited, but is preferably at least one of the compounds represented by any of the following general formulas (1) to (4).

Chemical formula

[0026] That is, the terminal-modified diene-based polymer according to the present embodiment is obtained by decomposing a diene-based polymer by oxidative cleavage at a carbon-carbon double bond present in its main chain, and reacting a system containing the decomposed polymer with a heterocyclic compound which is a nitrogen-containing unsaturated 5-membered or 6-membered ring compound having a primary amine to modify the terminal.

[0027] The diene-based polymer to be modified is a polymer containing a structural unit composed of a conjugated diene monomer, and may be a homopolymer of one type of conjugated diene monomer, a copolymer of two or more types of conjugated diene monomers, or a copolymer of one or two or more types of conjugated diene monomers and a vinyl monomer. For example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, etc. can be mentioned. These diene-based rubbers can be used alone or in a blend of two or more.

[0028] The diene-based polymer to be modified may be liquid at room temperature (23°C) or solid. The weight average molecular weight of the diene-based polymer is not particularly limited, and may be 10,000 to 4,000,000, may be 50,000 to 1,000,000, or may be 100,000 to 300,000. Here, in this specification, the weight average molecular weight is a value obtained by measuring the weight average molecular weight in terms of polystyrene by measurement using gel permeation chromatography (GPC).

[0029] The cis content of the diene polymer to be modified is not particularly limited, but from the viewpoint of promoting elongation crystallization, it is preferably 95% or more, more preferably 98% or more.

[0030] Also, the diene polymer may be dissolved in a solvent or dispersed in a dispersion medium, and it is preferable to use an aqueous emulsion in the form of micelles in water, which is a protic dispersion medium, that is, a rubber latex. By using an aqueous emulsion, after decomposing the polymer, a terminal modification reaction can be caused by blending a heterocyclic compound in that state. That is, it can be continuously synthesized in one container. The concentration of the aqueous emulsion (solid content concentration of the polymer) is not particularly limited, but it is preferably 5 to 70% by mass, more preferably 10 to 50% by mass. If the solid content concentration is too high, the emulsion stability will decrease, and if the solid content concentration is too low, the reaction rate will be slow and it will lack practicality.

[0031] The diene polymer is decomposed by the above oxidative cleavage, and a polymer having a carbonyl group (>C=O) or a formyl group (-CHO) at the terminal is obtained. Specifically, a polymer having a structure represented by the following formula (A) at the terminal is generated.

[0032]

Chemical formula

[0033] In formula (A), X is a hydrogen atom or a methyl group. When an isoprene unit is cleaved, X is a methyl group at one cleavage end and X is a hydrogen atom at the other cleavage end. In formula (A), P represents the polymer chain after oxidative cleavage.

[0034] In order to oxidatively cleave the carbon-carbon double bond of the diene polymer, an oxidizing agent can be used. For example, it can be oxidatively cleaved by adding an oxidizing agent to an aqueous emulsion of the diene polymer and stirring. Examples of the oxidizing agent include manganese compounds such as potassium permanganate and manganese oxide, chromium compounds such as chromic acid and chromium trioxide, peroxides such as hydrogen peroxide, perhalogenic acids such as periodic acid, oxygen-containing substances such as ozone and oxygen, and the like. Among these, it is preferable to use periodic acid. In the oxidative cleavage, a metal-based oxidation catalyst such as a chloride of a metal such as cobalt, copper, or iron, or a salt or complex with an organic compound may be used in combination. For example, it may be air-oxidized in the presence of the metal-based oxidation catalyst.

[0035] By decomposing the polymer by the above oxidative cleavage, the molecular weight decreases. The weight average molecular weight of the polymer after decomposition is not particularly limited, but is preferably 5,000 to 3,000,000, more preferably 300,000 to 2,000,000.

[0036] After decomposing the polymer as described above, the reaction system containing the decomposed polymer is reacted with the above heterocyclic compound. After the reaction, the aqueous emulsion is coagulation-dried to obtain a solid-terminal-modified diene polymer at room temperature (23°C). The obtained terminal-modified diene polymer preferably has a terminal structure represented by any of the above formulas (1a) to (1d), (2a) to (2d), (3a) to (3d), and (4a) to (4d).

[0037] For example, the terminal structures represented by the above formulas (1a) to (1d) are obtained by the following reaction. That is, a nucleophilic addition reaction of the heterocyclic compound represented by the formula (1) to the carbonyl group or formyl group of the structure represented by the general formula (A) results in a terminal structure represented by the general formula (1a) or (1b), and further dehydration reaction results in a terminal structure represented by the general formula (1c) or (1d).

[0038] The weight average molecular weight of the above-mentioned modified diene polymer is not particularly limited, but is preferably from 400,000 to 2,600,000, and more preferably from 600,000 to 2,000,000.

[0039] Further, according to the present embodiment, the reaction of oxidative cleavage can be controlled by adjusting the type and amount of an oxidizing agent, which is a drug for dissociating double bonds, the reaction time, and the like. By this control, the molecular weight of the terminal-modified diene polymer can be controlled.

[0040] The blending amount of the oxidizing agent is not particularly limited, but is preferably from 0.1 to 2.0 parts by mass, and more preferably from 0.2 to 0.6 parts by mass, based on 100 parts by mass of the diene polymer (solid content).

[0041] The blending amount of the heterocyclic compound, which is a nitrogen-containing unsaturated 5- or 6-membered ring compound having a primary amine, is not particularly limited, but is preferably from 0.05 to 1.0 mol, and more preferably from 0.1 to 0.5 mol, based on 1 kg of the diene polymer (solid content). When the blending amount is within the above range, excellent mechanical properties are easily obtained.

[0042] As in the present embodiment, by decomposing the polymer main chain and reacting a heterocyclic compound, which is a nitrogen-containing unsaturated 5- or 6-membered ring compound having a primary amine, a pseudo crosslink is formed by introducing a heterocyclic ring at the terminal. That is, the heterocyclic rings introduced at the terminals, or the interaction (such as van der Waals bond or hydrogen bond) between the heterocyclic ring and the carbonyl group or formyl group generated by the oxidative cleavage of the polymer physically bonds them, so that the terminal heterocyclic ring acts as a pseudo crosslinking point. By forming the pseudo crosslink, elongation crystallization is promoted and the effect of improving mechanical properties is obtained. Further, when a fracture energy is applied to the rubber composition containing the terminal-modified diene polymer, these pseudo crosslinks are preferentially broken while dispersing the fracture energy, so that the strength of the whole material is increased.

[0043] The rubber composition according to this embodiment may contain a diene rubber other than the above-mentioned terminally modified diene polymer as a rubber component, and the type thereof is not particularly limited. For example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, etc. may be mentioned. These diene rubbers can be used alone or in a blend of two or more.

[0044] In the rubber composition according to this embodiment, the content of the terminally modified diene polymer in 100 parts by mass of the rubber component is not particularly limited, but is preferably 10 to 100 parts by mass, more preferably 30 to 100 parts by mass, and even more preferably 50 to 100 parts by mass.

[0045] In the rubber composition according to this embodiment, a reinforcing filler such as carbon black or silica can be used as the inorganic filler. That is, the inorganic filler may be carbon black alone, silica alone, or a combination of carbon black and silica. Preferably, it is a combination of carbon black and silica. The content of the inorganic filler is not particularly limited. For example, with respect to 100 parts by mass of the rubber component, it is preferably 1 to 150 parts by mass, more preferably 1 to 100 parts by mass, and even more preferably 1 to 80 parts by mass.

[0046] The carbon black is not particularly limited, and various known varieties can be used. The content of the carbon black is preferably 1 to 70 parts by mass, more preferably 1 to 30 parts by mass, with respect to 100 parts by mass of the rubber component.

[0047] Although the silica is not particularly limited, wet silica such as wet precipitation silica and wet gel silica is preferably used. The content of silica is preferably 1 to 150 parts by mass, more preferably 1 to 100 parts by mass, and still more preferably 1 to 80 parts by mass with respect to 100 parts by mass of the rubber component from the viewpoints of the balance of tanδ of the rubber and the reinforcing property.

[0048] When containing silica, a silane coupling agent such as sulfide silane or mercapto silane may be further contained. When containing a silane coupling agent, the content thereof is preferably 2 to 20 parts by mass with respect to 100 parts by mass of silica.

[0049] In the rubber composition according to the present embodiment, in addition to the above-described respective components, additives such as process oil, zinc oxide, stearic acid, softening agent, plasticizer, wax, antioxidant, etc. used in the normal rubber industry, and vulcanizing agents, vulcanization accelerator and other vulcanization system compounding agents can be appropriately compounded within a normal range.

[0050] Examples of the vulcanizing agent include sulfur components such as powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersed sulfur. The content of the vulcanizing agent 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 rubber component. The content of the vulcanization accelerator is preferably 0.1 to 7 parts by mass, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

[0051] The rubber composition according to the present embodiment can be produced using a mixer such as a Banbury mixer, kneader, roll, etc. usually used.

[0052] The resulting rubber composition can be used for tires and can be applied to various parts of pneumatic tires, such as the tread and sidewall of pneumatic tires of various applications and sizes, including passenger car tires, large tires for trucks and buses. The rubber composition is formed into a predetermined shape by extrusion processing, for example, according to a conventional method, and after being combined with other parts, a pneumatic tire can be manufactured by vulcanization molding at, for example, 140 to 180 °C.

[0053] The type of pneumatic tire according to the present embodiment is not particularly limited, and as described above, various tires such as passenger car tires and heavy-duty tires used for trucks and buses can be mentioned.

Examples

[0054] Examples of the present invention are shown below, but the present invention is not limited to these examples.

[0055] [Comparative Synthesis Example 1] Water was added to IR latex to prepare 200 g of a 30% DRC solution. Sodium dodecyl sulfate (2.0 g) was added, and after stirring for 1 hour under a nitrogen atmosphere, tert-butyl hydroperoxide (0.93 mL) and tetraethylenepentamine (1.3 mL) were added, and the mixture was stirred at 60 °C for 3 hours. The obtained reaction solution was dropped into acetone to aggregate the rubber component. The obtained rubber component was washed with water and dried under reduced pressure at 50 °C to obtain an oxidative degradation diene polymer 1.

[0056] [Comparative Synthesis Example 2] Water was added to IR latex to prepare 200 g of a 30% DRC solution. Sodium dodecyl sulfate (2.0 g) was added, and after stirring for 1 hour under a nitrogen atmosphere, tert-butyl hydroperoxide (0.47 mL) and tetraethylenepentamine (0.65 mL) were added, and the mixture was stirred at 60 °C for 3 hours. The obtained reaction solution was dropped into acetone to aggregate the rubber component. The obtained rubber component was washed with water and dried under reduced pressure at 50 °C to obtain an oxidative degradation diene polymer 2.

[0057] [Synthesis Example 1] Water was added to IR latex to prepare 200 g of a 30% DRC solution. Sodium dodecyl sulfate (2.0 g) was added, and after stirring for 1 hour under a nitrogen atmosphere, tert-butyl hydroperoxide (0.93 mL) and tetraethylenepentamine (1.3 mL) were added and stirred at 60 °C for 3 hours. Then, 3-amino-1,2,4-triazole (0.28 g) and 1,8-diazabicyclo[5.4.0]-7-undecene (0.56 ml) were added and stirred at 60 °C overnight. The resulting reaction solution was dropped into acetone to agglomerate the rubber component. The obtained rubber component was washed with water and dried under reduced pressure at 50 °C to obtain terminal-modified diene polymer 1. The weight average molecular weight was 8.07×10 5 It was.

[0058] [Synthesis Example 2] Water was added to IR latex to prepare 200 g of a 30% DRC solution. Sodium dodecyl sulfate (2.0 g) was added, and after stirring for 1 hour under a nitrogen atmosphere, tert-butyl hydroperoxide (0.93 mL) and tetraethylenepentamine (1.3 mL) were added and stirred at 60 °C for 3 hours. Then, 3-amino-1,2,4-triazole (0.57 g) and 1,8-diazabicyclo[5.4.0]-7-undecene (1.1 ml) were added and stirred at 60 °C overnight. The resulting reaction solution was dropped into acetone to agglomerate the rubber component. The obtained rubber component was washed with water and dried under reduced pressure at 50 °C to obtain terminal-modified diene polymer 2. The weight average molecular weight was 9.50×10 5 It was.

[0059] [Synthesis Example 3] Water was added to IR latex to prepare 200 g of a 30% DRC solution. Sodium dodecyl sulfate (2.0 g) was added and the mixture was stirred for 1 hour under a nitrogen atmosphere. Then, tert-butyl hydroperoxide (0.93 mL) and tetraethylenepentamine (1.3 mL) were added and the mixture was stirred at 60 °C for 3 hours. Thereafter, 3-amino-1,2,4-triazole (1.14 g) and 1,8-diazabicyclo[5,4,0]-7-undecene (2.2 mL) were added and the mixture was stirred at 60 °C overnight. The resulting reaction solution was dropped into acetone to agglomerate the rubber component. The obtained rubber component was washed with water and dried under reduced pressure at 50 °C to obtain a terminally modified diene polymer 3. The weight average molecular weight was 10.1×10 5 It was.

[0060] [Synthesis Example 4] Water was added to IR latex to prepare 200 g of a 30% DRC solution. Sodium dodecyl sulfate (2.0 g) was added and the mixture was stirred for 1 hour under a nitrogen atmosphere. Then, tert-butyl hydroperoxide (0.93 mL) and tetraethylenepentamine (1.3 mL) were added and the mixture was stirred at 60 °C for 3 hours. Thereafter, 3-amino-1,2,4-triazole (1.71 g) and 1,8-diazabicyclo[5,4,0]-7-undecene (3.3 mL) were added and the mixture was stirred at 60 °C overnight. The resulting reaction solution was dropped into acetone to agglomerate the rubber component. The obtained rubber component was washed with water and dried under reduced pressure at 50 °C to obtain a terminally modified diene polymer 4. The weight average molecular weight was 10.1×10 5 It was.

[0061] [Synthesis Example 5] Water was added to IR latex to prepare 200 g of a 30% DRC solution. Sodium dodecyl sulfate (2.0 g) was added, and after stirring for 1 hour under a nitrogen atmosphere, tert-butyl hydroperoxide (0.93 mL) and tetraethylenepentamine (1.3 mL) were added, and the mixture was stirred at 60 °C for 3 hours. Then, 2-aminopyrimidine (0.32 g) and 1,8-diazabicyclo[5.4.0]-7-undecene (0.56 ml) were added, and the mixture was stirred at 60 °C overnight. The resulting reaction solution was dropped into acetone to aggregate the rubber component. The obtained rubber component was washed with water and dried under reduced pressure at 50 °C to obtain a terminally modified diene polymer 5. The weight average molecular weight was 7.41×10 5 It was.

[0062] [Synthesis Example 6] Water was added to IR latex to prepare 200 g of a 30% DRC solution. Sodium dodecyl sulfate (2.0 g) was added, and after stirring for 1 hour under a nitrogen atmosphere, tert-butyl hydroperoxide (0.93 mL) and tetraethylenepentamine (1.3 mL) were added, and the mixture was stirred at 60 °C for 3 hours. Then, 2-aminopyrimidine (0.64 g) and 1,8-diazabicyclo[5.4.0]-7-undecene (1.1 ml) were added, and the mixture was stirred at 60 °C overnight. The resulting reaction solution was dropped into acetone to aggregate the rubber component. The obtained rubber component was washed with water and dried under reduced pressure at 50 °C to obtain a terminally modified diene polymer 6. The weight average molecular weight was 6.54×10 5 It was.

[0063] [Synthesis Example 7] Water was added to IR latex to prepare 200 g of a solution with 30% DRC. Sodium dodecyl sulfate (2.0 g) was added, and after stirring for 1 hour under a nitrogen atmosphere, tert-butyl hydroperoxide (0.93 mL) and tetraethylenepentamine (1.3 mL) were added, followed by stirring at 60 °C for 3 hours. Then, 2-aminopyrimidine (1.29 g) and 1,8-diazabicyclo[5.4.0]-7-undecene (2.2 mL) were added, and the mixture was stirred at 60 °C overnight. The resulting reaction solution was dropped into acetone to agglomerate the rubber component. The obtained rubber component was washed with water and dried under reduced pressure at 50 °C to obtain a terminally modified diene polymer 7. The weight average molecular weight was 7.10×10 5 was obtained.

[0064] [Synthesis Example 8] Water was added to IR latex to prepare 200 g of a solution with 30% DRC. Sodium dodecyl sulfate (2.0 g) was added, and after stirring for 1 hour under a nitrogen atmosphere, tert-butyl hydroperoxide (0.47 mL) and tetraethylenepentamine (0.65 mL) were added, followed by stirring at 60 °C for 3 hours. Then, 2-aminopyrimidine (0.32 g) and 1,8-diazabicyclo[5.4.0]-7-undecene (0.56 mL) were added, and the mixture was stirred at 60 °C overnight. The resulting reaction solution was dropped into acetone to agglomerate the rubber component. The obtained rubber component was washed with water and dried under reduced pressure at 50 °C to obtain a terminally modified diene polymer 8. The weight average molecular weight was 9.50×10 5 was obtained.

[0065] [Synthesis Example 9] Water was added to IR latex to prepare 200 g of a 30% DRC solution. Sodium dodecyl sulfate (2.0 g) was added, and after stirring for 1 hour under a nitrogen atmosphere, tert-butyl hydroperoxide (0.47 mL) and tetraethylenepentamine (0.65 mL) were added, followed by stirring at 60 °C for 3 hours. Then, 2-aminopyrimidine (0.64 g) and 1,8-diazabicyclo[5.4.0]-7-undecene (1.1 ml) were added, and the mixture was stirred at 60 °C overnight. The resulting reaction solution was dropped into acetone to agglomerate the rubber component. The obtained rubber component was washed with water and dried under reduced pressure at 50 °C to obtain a terminal-modified diene polymer 9. The weight average molecular weight was 9.86×10 5 It was.

[0066] [Synthesis Example 10] Water was added to IR latex to prepare 200 g of a 30% DRC solution. Sodium dodecyl sulfate (2.0 g) was added, and after stirring for 1 hour under a nitrogen atmosphere, tert-butyl hydroperoxide (0.47 mL) and tetraethylenepentamine (0.65 mL) were added, followed by stirring at 60 °C for 3 hours. Then, 2-aminopyrimidine (0.96 g) and 1,8-diazabicyclo[5.4.0]-7-undecene (1.7 ml) were added, and the mixture was stirred at 60 °C overnight. The resulting reaction solution was dropped into acetone to agglomerate the rubber component. The obtained rubber component was washed with water and dried under reduced pressure at 50 °C to obtain a terminal-modified diene polymer 10. The weight average molecular weight was 9.78×10 5 It was.

[0067] The weight average molecular weight of the terminal-modified diene polymer obtained above was measured by the following method.

[0068] [Weight average molecular weight (Mw)] By measurement with gel permeation chromatography (GPC), Mn, Mw and Mw / Mn in terms of polystyrene were determined. Specifically, the measurement sample used was one dissolved in 1 mL of THF. Using "LC-20DA" manufactured by Shimadzu Corporation, after the sample was filtered, it was passed through a column (Shodex KL-807L) at a temperature of 40 °C and a flow rate of 1.0 mL / min, and detected with a differential refractive index detector (RI).

[0069] Details of each component used in the synthesis example are as follows. · IR latex: "IRL701" manufactured by BST Specialty CO., Ltd., weight average molecular weight = 16.0×10 5 , cis content = 98.99% · Sodium dodecyl sulfate: manufactured by Fujifilm Wako Pure Chemical Corporation · tert-Butyl hydroperoxide: manufactured by Tokyo Chemical Industry Co., Ltd. · Tetraethylenepentamine: manufactured by Tokyo Chemical Industry Co., Ltd. · 3-Amino-1,2,4-triazole: manufactured by Tokyo Chemical Industry Co., Ltd. · 2-Aminopyrimidine: manufactured by Tokyo Chemical Industry Co., Ltd. · 1,8-Diazabicyclo〔5,4,0〕-7-undecene: manufactured by Nacalai Tesque, Inc. · Diazabicycloundecene: manufactured by Tokyo Chemical Industry Co., Ltd. · Acetone: manufactured by Nacalai Tesque, Inc.

[0070] Using the obtained terminally modified diene polymer, a rubber composition was prepared according to the formulations shown in Tables 1 and 2 and vulcanized at 150 °C for 25 minutes. The mechanical strength of the obtained vulcanized rubber composition was evaluated according to the following measurement methods.

[0071] Details of each component used in the example are as follows. · Oxidatively decomposed diene polymers 1 and 2: Oxidatively decomposed diene polymers obtained in Comparative Synthesis Examples 1 and 2 above · Terminally modified diene polymers 1 to 10: Terminally modified diene polymers obtained in Synthesis Examples 1 to 10 above · Carbon black: "N339 Seast KH" manufactured by Tokai Carbon Co., Ltd. · Zinc oxide: "Zinc Oxide Type 1" manufactured by Mitsui Mining & Smelting Co., Ltd. · Stearic acid: "Lunac S-20" manufactured by Kao Corporation · Sulfur: "Powdered Sulfur for Rubber 150 Mesh" manufactured by Hosoi Chemical Industry Co., Ltd. · Vulcanization accelerator: "Nocceler CZ" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0072] [Tensile stress (MPa) at 300% elongation] A tensile test (dumbbell-shaped No. 7) in accordance with JIS K6251 was conducted to measure the tensile stress (Mpa) at 300% elongation at 25°C. For Examples 1 to 7, the value of Comparative Example 1 was taken as 100, and for Examples 8 to 10, the value of Comparative Example 1 was taken as 100 and expressed as an index. The larger the index, the better the fracture characteristics (mechanical strength).

[0073]

Table 1

Table 2

[0074] The results are as shown in Tables 1 and 2. In Examples 1 to 10, fracture characteristics (mechanical strength) superior to those of Comparative Examples 1 and 2 were obtained. From these results, it is also suggested that due to the introduction of the heterocyclic ring, the heterocyclic rings introduced at the terminals and the carbonyl groups and formyl groups generated by the oxidative cleavage of the heterocyclic ring and the polymer interact (van der Waals bonds and hydrogen bonds).

Industrial Applicability

[0075] The rubber composition using the terminal-modified diene polymer of the present invention can be used for various tires such as passenger cars, light trucks, and buses.

Claims

1. A terminally modified diene polymer obtained by reacting a diene polymer having a ketone group or an aldehyde group at its terminal with at least one heterocyclic compound selected from the compounds represented by the following general formulas (1) to (4). 【Chemical 1】 However, in formulas (1) to (4), R1 to R10 represent hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and they may be the same or different from each other.

2. The terminally modified diene polymer according to Claim 1, wherein the addition amount of the heterocyclic compound is 0.01 to 0.5 mol per 1 kg of the diene polymer.

3. The terminally modified diene polymer according to Claim 1 or 2, having a weight average molecular weight of 400,000 to 2,600,000.

4. An oxidative decomposition step of adding an oxidizing agent to a diene polymer to oxidatively cleave a carbon-carbon double bond to obtain an oxidatively decomposed diene polymer; A method for producing a terminally modified diene polymer, comprising a terminal modification step of reacting the obtained oxidatively decomposed diene polymer with at least one heterocyclic compound selected from the compounds represented by the following general formulas (1) to (4). [Chemical Formula 2] However, in formulas (1) to (4), R1 to R10 represent hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and they may be the same or different from each other.

5. The method for producing a terminally modified diene polymer according to Claim 4, wherein the addition amount of the heterocyclic compound is 0.01 to 0.5 mol per 1 kg of the diene polymer.

6. The method for producing a terminally modified diene polymer according to Claim 4 or 5, wherein a rubber latex is used as the diene polymer.

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