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 an aminophosphonic acid compound represented by general formula (1) or (2).SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Various means for improving 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 a manganese catalyst having an acetylacetonate ligand is used when reacting the polymer with the compound. However, since the addition reaction of the phosphate group consumes the double bond, there is a risk of a decrease in crosslink density.

[0003] Further, Patent Document 2 describes that carboxy ions are introduced and their ionic bonds are formed to significantly improve mechanical strength. However, containing ionic functional groups in rubber makes it 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] Further, Patent Document 3 describes that a crosslinked structure is created by introducing host and guest molecules into the polymer chain, and the mechanical strength is improved by their host-guest interaction. However, cyclodextrin used as the host molecule is expensive and has low compatibility with rubber, so there is a problem that it aggregates in 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 the terminal with an aminophosphonic acid compound represented by the general formula (1) or (2) in order to solve the above problems.

CHEMICAL FORMULA

[0008] The addition amount of the above aminophosphonic acid compound can be 0.01 to 0.5 mol per 1 kg of the above diene-based polymer.

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

[0010] 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 an aminophosphonic acid compound represented by the general formula (1) or (2).

CHEMICAL FORMULA

[0011] The addition amount of the above aminophosphonic acid compound can be 0.01 to 0.5 mol per 1 kg of the above diene-based polymer.

[0012] A rubber latex can be used as the above diene-based polymer.

Advantages of the Invention

[0013] 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.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, matters related to the implementation of the present invention will be described in detail.

[0015] 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 an aminophosphonic acid compound represented by the general formula (1) or (2).

Chemical formula

[0016] The terminal-modified diene polymer preferably has at least one of the structures represented by general formulas (1a) to (1d) and (2a) to (2d) at its terminal. However, in formulas (1a) to (1d) and (2a) to (2d), R1 and R4 represent an alkanediyl group having 1 to 10 carbon atoms, R2, R3, R5, R6, R8, and R9 represent hydrogen, an alkyl group having 1 to 3 carbon atoms, or a phenyl group, and R7 represents hydrogen or a hydroxyl group.

[0017]

Chemical formula

[0018]

Chemical formula

[0019] The method for producing a 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 the above aminophosphonic acid compound 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.

[0020] That is, the terminal-modified diene polymer according to this embodiment is obtained by decomposing a diene polymer by oxidatively cleaving a carbon-carbon double bond present in its main chain, and reacting a system containing the decomposed polymer with an aminophosphonic acid compound to modify the terminal.

[0021] The diene polymer to be modified is a polymer containing a structural unit composed of a conjugated diene monomer, which 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 rubbers can be used alone or in a blend of two or more.

[0022] The diene polymer to be modified may be liquid at room temperature (23 °C) or in a solid state. The weight average molecular weight of the diene 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 the value obtained by measuring the weight average molecular weight in terms of polystyrene by measurement with gel permeation chromatography (GPC).

[0023] 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, and more preferably 98% or more.

[0024] The diene polymer may be either dissolved in a solvent or dispersed in a dispersion medium, and it is preferable to use an aqueous emulsion in a micellar state in a protic dispersion medium, i.e., a rubber latex. By using an aqueous emulsion, after decomposing the polymer, the terminal modification reaction can be caused by blending the aminophosphonic acid compound in that state. That is, it can be continuously synthesized in one container. The concentration of the aqueous emulsion (the solid content concentration of the polymer) is not particularly limited, but 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.

[0025] By the above oxidative cleavage, the diene polymer is decomposed, 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.

[0026]

Chemical formula

[0027] In formula (A), X is a hydrogen atom or a methyl group. When the isoprene unit is cleaved, at one cleavage end, X is a methyl group, and at the other cleavage end, X is a hydrogen atom. In formula (A), P represents the polymer chain after oxidative cleavage.

[0028] 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, and oxygen-containing substances such as ozone and oxygen. 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.

[0029] 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.

[0030] After decomposing the polymer as described above, the reaction system containing the decomposed polymer is reacted with an aminophosphonic acid compound. After the reaction, the aqueous emulsion is coagulated and 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).

[0031] 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 aminophosphonic acid 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 when a dehydration reaction further occurs, a terminal structure represented by the general formula (1c) or (1d) is obtained.

[0032] 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.

[0033] Further, according to the present embodiment, the reaction of oxidative cleavage can be controlled by adjusting the type and amount of the 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.

[0034] The compounding 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 with respect to 100 parts by mass of the diene polymer (solid content).

[0035] The compounding amount of the aminophosphonic acid compound is not particularly limited, but is preferably from 0.05 to 1.0 mol, and more preferably from 0.1 to 0.5 mol with respect to 1 kg of the diene polymer (solid content). When the compounding amount is within the above range, excellent mechanical properties are easily obtained.

[0036] As in the present embodiment, by decomposing the polymer main chain and reacting the aminophosphonic acid compound to introduce phosphonic acid at the terminal, pseudo-crosslinking is formed. That is, the phosphonic acids introduced at the terminals, or the interaction (such as van der Waals bond or hydrogen bond) between the phosphonic acid and the carbonyl group or formyl group generated by the oxidative cleavage of the polymer physically bonds, so that the phosphonic acid at the terminal acts as a pseudo-crosslinking point. By forming pseudo-crosslinking, elongation crystallization is promoted and an effect of improving mechanical properties is obtained. Further, when 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 entire material is increased.

[0037] 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. 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.

[0038] 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.

[0039] In the rubber composition according to this embodiment, a reinforcing filler such as carbon black or silica can be used as an 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.

[0040] 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.

[0041] Although the silica is not particularly limited, wet silica such as wet precipitation method silica and wet gel method 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.

[0042] 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.

[0043] In the rubber composition according to the present embodiment, in addition to the above-described components, additives such as process oil, zinc oxide, stearic acid, softening agent, plasticizer, wax, antioxidant, etc. used in the ordinary rubber industry, and vulcanizing agents, vulcanization accelerators and other vulcanization system compounding agents can be appropriately compounded within a normal range.

[0044] 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.

[0045] The rubber composition according to the present embodiment can be produced using a mixer such as a Banbury mixer, kneader, roll, etc. usually used.

[0046] 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 for various applications and sizes, including passenger car tires, large tires for trucks and buses, etc. 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.

[0047] The type of pneumatic tire according to this 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

[0048] Examples of the present invention are shown below, but the present invention is not limited to these examples.

[0049] [Comparative Synthesis Example] 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 and stirred at 60 °C for 3 hours. 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 an oxidative degradation diene-based polymer.

[0050] [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 (0.47 mL) and tetraethylenepentamine (0.65 mL) were added, followed by stirring at 60 °C for 3 hours. Then, ethanolamine phosphate (0.24 g) and 1,8-diazabicyclo[5.4.0]-7-undecene (0.28 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 1. The weight average molecular weight was 7.17×10 5 was obtained.

[0051] [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, followed by stirring at 60 °C for 3 hours. Then, ethanolamine phosphate (0.48 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 2. The weight average molecular weight was 7.22×10 5 was obtained.

[0052] [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 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. Thereafter, ethanolamine phosphate (0.95 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 3. The weight average molecular weight was 6.86×10 5 It was.

[0053] [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 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. Thereafter, alendronic acid (0.42 g) and 1,8-diazabicyclo[5.4.0]-7-undecene (0.28 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 4. The weight average molecular weight was 10.5×10 5 It was.

[0054] [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 (0.47 mL) and tetraethylenepentamine (0.65 mL) were added, and the mixture was stirred at 60 °C for 3 hours. Then, alendronic acid (0.84 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 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 a terminally modified diene polymer 5. The weight average molecular weight was 11.2×10 5 It was.

[0055] The weight average molecular weight of the terminally modified diene polymer obtained above was measured by the following method.

[0056] [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).

[0057] 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 Fuji Film Wako Pure Chemical Corporation · tert-Butyl hydroperoxide: manufactured by Tokyo Chemical Industry Co., Ltd. · Tetraethylenepentamine: manufactured by Tokyo Chemical Industry Co., Ltd. · Ethanolamine phosphate: manufactured by Tokyo Chemical Industry Co., Ltd. · Alendronic acid: 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.

[0058] Using the obtained terminally modified diene polymer, a rubber composition was prepared according to the formulation shown in Table 1 and vulcanized at 150 °C for 25 minutes. For the obtained vulcanized rubber composition, the mechanical strength was evaluated according to the following measurement methods.

[0059] Details of each component used in the examples are as follows. · Oxidatively decomposed diene polymer: the oxidatively decomposed diene polymer obtained in the above Comparative Synthesis Example · Terminally modified diene polymers 1 to 5: the terminally modified diene polymers obtained in the above Synthesis Examples 1 to 5 · Carbon black: "N339 Sheet 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 Shinsei Chemical Industry Co., Ltd.

[0060] [Tensile stress at 300% elongation (MPa)] A tensile test (dumbbell shape No. 7) was conducted in accordance with JIS K6251, and the tensile stress (Mpa) at 300% elongation at 25 °C was measured and expressed as an index with the value of Comparative Example 1 taken as 100. The larger the index, the better the fracture characteristics (mechanical strength).

[0061]

Table 1

[0062] The results are as shown in Table 1. In Examples 1 to 5, fracture properties (mechanical strength) superior to those of Comparative Example 1 were obtained. From these results, it is also suggested that the introduced phosphonic acids interact (van der Waals bonds and hydrogen bonds) with each other and with the carbonyl groups and formyl groups generated by oxidative cleavage of the phosphonic acid and the polymer at the terminal.

Industrial Applicability

[0063] 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 an aminophosphonic acid compound represented by the general formula (1) or (2). 【Chemical 1】 However, in formulas (1) and (2), R １ , R ４ represents an alkanediyl group having 1 to 10 carbon atoms, and R ２ , R ３ , R ５ , R ６ , R ８ , R ９ represents hydrogen, an alkyl group having 1 to 3 carbon atoms, or a phenyl group, and R ７ represents hydrogen or a hydroxyl group.

2. The terminally modified diene polymer according to Claim 1, wherein the addition amount of the aminophosphonic acid 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, and A method for producing a terminally modified diene polymer, comprising a terminal modification step of reacting the obtained oxidatively decomposed diene polymer with an aminophosphonic acid compound represented by the general formula (1) or (2). [Chemical Formula 2] However, in formulas (1) and (2), R １ , R ４ represents an alkanediyl group having 1 to 10 carbon atoms, and R ２ , R ３ , R ５ , R ６ , R ８ , R ９ represents hydrogen, an alkyl group having 1 to 3 carbon atoms, or a phenyl group, and R ７ represents hydrogen or a hydroxyl group.

5. The method for producing a terminally modified diene polymer according to Claim 4, wherein the addition amount of the aminophosphonic acid 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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