Terminally modified diene polymer and method for producing same

Abstract

To provide a diene polymer having excellent silica adsorptivity, and a method for producing the same.SOLUTION: An end-modified diene polymer is a diene polymer having, at its end, a functional group having a carboxy group or its alkyl ester or silyl ester and an alkoxysilyl group.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Diene polymers having adsorption properties to silica (silica adsorption properties) have been proposed (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-29531 Summary of the Invention [Problem to be solved by the invention]

[0004] Under these circumstances, the present inventors have investigated the diene polymer described in Patent Document 1 and have found that further improvement in silica adsorption is desirable in view of various applications.

[0005] In view of the above circumstances, an object of the present invention is to provide a diene polymer having excellent silica adsorption properties and a method for producing the same. [Means for solving the problem]

[0006] As a result of intensive research into the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by introducing a functional group having a carboxy group or its alkyl ester or silyl ester and an alkoxysilyl group into the terminal, and have arrived at the present invention. That is, the present inventors have found that the above problems can be solved by the following configuration.

[0007] (1) A terminal-modified diene polymer, which is a diene polymer having at its terminal a functional group having a carboxyl group or its alkyl ester or silyl ester and an alkoxysilyl group. (2) The terminal-modified diene polymer according to (1) above, wherein the functional group is a group represented by formula (I) below. (3) The terminal-modified diene polymer according to (1) above, wherein the functional group is a group represented by formula (II) described below. (4) The terminal-modified diene polymer according to any one of (1) to (3) above, which has a weight-average molecular weight of 1,000 to 10,000,000. (5) A terminal-modified diene polymer according to any one of (1) to (4) above, wherein the diene that constitutes the repeating unit of the diene polymer is 1,3-butadiene or isoprene. (6) The terminal-modified diene polymer according to any one of (1) to (5) above, wherein the monomer that constitutes the repeating unit of the diene polymer contains an aromatic vinyl as a monomer other than the diene. (7) a polymerization step of anionically polymerizing a diene-containing monomer to obtain a diene-based polymer having an active terminal; and a terminal modification step of reacting the diene polymer having an active terminal obtained in the polymerization step with a compound having an alkyl ester or silyl ester of a carboxy group and an alkoxysilyl group to obtain a terminal-modified diene polymer, which is a diene polymer having a functional group having an alkyl ester or silyl ester of a carboxy group and an alkoxysilyl group at its terminal. A method for producing a terminally modified diene polymer. (8) The method for producing a terminally modified diene polymer according to (7) above, wherein the compound is a compound represented by formula (III) below. (9) A method for producing a terminal-modified diene polymer, comprising hydrolyzing a terminal-modified diene polymer obtained by the production method described in (7) or (8) above to obtain a terminal-modified diene polymer, which is a diene polymer having functional groups having a carboxy group and an alkoxysilyl group at its terminals. [Effects of the Invention]

[0008] As described below, the present invention provides a diene polymer having excellent silica adsorption properties and a method for producing the same. The terminal-modified diene polymer of the present invention also has excellent mechanical properties (e.g., elongation at break, stress at break) and abrasion resistance, and also has the effect of preventing silica from being desorbed even when exposed to a high-temperature environment or a humid and hot environment after silica adsorption. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a 1H-NMR spectrum of a terminally modified diene-based polymer 5. DETAILED DESCRIPTION OF THE INVENTION

[0010] The terminally modified diene polymer of the present invention and its production method will be described below. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In addition, in this specification, each component may be used alone or in combination of two or more. When two or more components are used in combination, the amount of each component refers to the total amount unless otherwise specified. In addition, in this specification, hydrocarbon groups (such as alkyl groups, alkylene groups, and alkyl groups in alkoxy groups) may have heteroatoms, and their shape (straight-chain, branched, cyclic) is not particularly limited.

[0011] [1] Terminally modified diene polymer The terminally modified diene polymer of the present invention (hereinafter also referred to as "the polymer of the present invention") is a diene polymer having, at its terminal, a functional group having a carboxy group or its alkyl ester or silyl ester (hereinafter, "carboxy group or its alkyl ester or silyl ester" will also be collectively referred to as "carboxy groups") and an alkoxysilyl group.

[0012] The polymer of the present invention has such a structure and is therefore believed to be able to solve the above-mentioned problems of the present invention. Although the reason for this is not clear, it is presumed that the carboxyl groups act as catalysts for the reaction between the alkoxysilyl groups and the silanol groups of silica, thereby exhibiting extremely excellent adsorption properties for silica.

[0013] The polymer of the present invention will be described in detail below.

[0014] [Skeleton] The skeleton (main chain structure) of the polymer of the present invention is not particularly limited as long as it is a diene-based polymer. The diene polymer is a polymer of a monomer containing a diene. The diene polymer may be a homopolymer or a copolymer, but is preferably a homopolymer because the effects of the present invention are more excellent.

[0015] [Diene] Specific examples of the diene include butadiene (particularly 1,3-butadiene), isoprene, chloroprene, etc. The diene is preferably butadiene (particularly 1,3-butadiene) or isoprene, and more preferably butadiene (particularly 1,3-butadiene), because the effects of the present invention are more excellent.

[0016] [Monomers other than dienes] The diene-containing monomer may also contain a monomer other than a diene. The monomer other than the diene is not particularly limited, and examples thereof include aromatic vinyl (preferably styrene), acrylonitrile, ethylene, propylene, butene (preferably isobutylene), etc. The monomer other than the diene is preferably aromatic vinyl, and more preferably styrene, because the effects of the present invention are more excellent.

[0017] [Content] The content of diene in all monomers that become repeating units of the diene polymer is not particularly limited, but in order to obtain better effects of the present invention, it is preferably 10% by mass or more, more preferably 50% by mass or more, and even more preferably 90% by mass or more. The content of diene in all monomers is not particularly limited, and is 100% by mass.

[0018] When the diene-containing monomer contains an aromatic vinyl as a monomer other than the diene, the content of the diene in all monomers that become repeating units of the diene-based polymer is preferably 10 to 99 mass%, more preferably 30 to 95 mass%, even more preferably 50 to 90 mass%, and particularly preferably 60 to 80 mass%, for reasons of better effects of the present invention. Furthermore, when the diene-containing monomer contains an aromatic vinyl as a monomer other than the diene, the content of the aromatic vinyl in all monomers that become repeating units of the diene-based polymer is preferably 1 to 90 mass%, more preferably 5 to 70 mass%, even more preferably 10 to 50 mass%, and particularly preferably 20 to 40 mass%, for reasons of better effects of the present invention.

[0019] [Specific example] Specific examples of the diene polymer include butadiene polymer (BR), isoprene polymer (IR), chloroprene polymer (CR), isoprene-butadiene copolymer (IBR), butadiene-styrene copolymer (SBR), acrylonitrile-butadiene copolymer (NBR), isobutylene-isoprene copolymer, etc. Among these, BR, IR, and SBR are preferred, BR and SBR are more preferred, and BR is even more preferred, because they provide better effects of the present invention.

[0020] [Preferred embodiment] The diene that constitutes the repeating unit of the diene polymer is preferably 1,3-butadiene or isoprene, and more preferably 1,3-butadiene, because this provides better effects of the present invention. The monomer that becomes the repeating unit of the diene polymer preferably contains an aromatic vinyl as a monomer other than the diene, because this provides a more excellent effect of the present invention.

[0021] [Specific functional group] The polymer of the present invention has a functional group having a carboxy group or its alkyl ester or silyl ester and an alkoxysilyl group (hereinafter also referred to as a "specific functional group") at its terminal. The polymer of the present invention may have a specific functional group at at least one end. The polymer of the present invention preferably has a specific functional group at only one end, because this provides a better effect of the present invention. The polymer of the present invention may have a functional group in the main chain as well, but it is preferable that the main chain does not have a functional group because the effect of the present invention is more excellent.

[0022] [Carboxy group or its (silyl) ester] As mentioned above, the specific functional group has a carboxy group (-COOH) or an alkyl ester or silyl ester thereof. Here, an alkyl ester of a carboxy group is an ester of a carboxy group with an alcohol (-COOCR3, where R is a hydrogen atom or a substituent), and a silyl ester of a carboxy group is an ester of a carboxy group with a silanol (-COOSiR3, where R is a hydrogen atom or a substituent). Hereinafter, alkyl esters and silyl esters are collectively referred to as "(silyl) esters." The above-mentioned substituent is preferably a hydrocarbon group because the effects of the present invention are more excellent. Examples of the hydrocarbon group include aliphatic hydrocarbon groups, aromatic hydrocarbon groups, and groups formed by combining these groups. The aliphatic hydrocarbon group may be linear, branched, or cyclic. Specific examples of the aliphatic hydrocarbon group include linear or branched alkyl groups (particularly having 1 to 30 carbon atoms), linear or branched alkenyl groups (particularly having 2 to 30 carbon atoms), and linear or branched alkynyl groups (particularly having 2 to 30 carbon atoms). Examples of the aromatic hydrocarbon group include aromatic hydrocarbon groups having 6 to 18 carbon atoms, such as a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. The substituent is preferably a hydrocarbon group, more preferably an aliphatic hydrocarbon group, further preferably a linear or branched alkyl group, and particularly preferably a branched alkyl group, for reasons of better effects of the present invention.

[0023] The (silyl) ester of the carboxy group is preferably an ester of a carboxy group and a silanol, because this provides a better effect of the present invention.

[0024] The carboxy group or its (silyl) ester is preferably a carboxy group, since this provides better effects of the present invention.

[0025] [Alkoxysilyl group] As described above, the specific functional group has an alkoxysilyl group. Here, the alkoxysilyl group is a group represented by ≡SiOR (where R is a hydrocarbon group). The alkoxysilyl group is preferably —Si(R 1 ) m (R 2 ) n It is preferable that the group is a group represented by the following formula: where R 1 represents an alkoxy group, and R 2 represents a hydrogen atom or a substituent, m represents an integer of 1 to 3, n represents an integer of 0 to 2, and m+n is 3. Above R 1 is preferably an alkoxy group having 1 to 10 carbon atoms, and more preferably an alkoxy group having 1 to 5 carbon atoms, because this provides better effects of the present invention. Above R 2 When R is a substituent, specific examples and preferred embodiments are the same as those of the (silyl) ester of the carboxy group described above. 2is preferably an alkyl group having 1 to 5 carbon atoms, because this provides better effects of the present invention. The above m is preferably an integer of 2 to 3, and more preferably 3, for the reason that the effects of the present invention are more excellent. The above n is preferably an integer of 0 to 1, and more preferably 0, because the effects of the present invention are more excellent.

[0026] [Preferred embodiment] The specific functional group is preferably a group represented by the following formula (I) or (II), and more preferably a group represented by the following formula (II), because the effects of the present invention are more excellent. The group represented by the following formula (I) is a functional group having a (silyl) ester of a carboxy group and an alkoxysilyl group, and the group represented by the following formula (II) is a functional group having a carboxy group and an alkoxysilyl group.

[0027] [ka]

[0028] In the above formula (I), R 1 and R 2 each independently represents an alkyl group having 1 to 10 carbon atoms or a phenyl group, n represents an integer of 0 to 1, R 3 represents an alkylene group having 1 to 10 carbon atoms which may contain an oxygen atom, or an aromatic ring; R 4 and R 5 each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, A represents a carbon atom or a silicon atom, and R 6 represents an alkyl group having 1 to 10 carbon atoms.

[0029] Above R 1 is preferably an alkyl group having 1 to 5 carbon atoms, because this provides better effects of the present invention. Above R 2 is preferably an alkyl group having 1 to 5 carbon atoms, because this provides better effects of the present invention. The above n is preferably 0 because the effects of the present invention are more excellent. Above R 3 is preferably an alkylene group having 1 to 10 carbon atoms, and more preferably an alkylene group having 1 to 5 carbon atoms, because this provides better effects of the present invention. 3 Specific examples of alkylene groups containing an oxygen atom include -(RO) n - (wherein R is an alkylene group, and n is an integer of 1 to 10) is exemplified. The above A is preferably a silicon atom, since this provides a better effect of the present invention. Above R 6 is preferably an alkyl group (particularly a branched group) having 2 to 5 carbon atoms, because this provides better effects of the present invention.

[0030] [ka]

[0031] In the above formula (II), R 1 and R 2 each independently represents an alkyl group having 1 to 10 carbon atoms or a phenyl group, n represents an integer of 0 to 1, R 3 represents an alkylene group having 1 to 10 carbon atoms which may contain an oxygen atom, or an aromatic ring; R 4 and R 5 each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

[0032] R in the above formula (II) 1 Specific examples and preferred embodiments of each symbol such as are the same as those in formula (I) above.

[0033] [Molecular weight] The weight average molecular weight (Mw) of the polymer of the present invention is preferably 500 to 10,000,000, more preferably 1,000 to 5,000,000, and even more preferably 10,000 to 1,000,000, for reasons of better effects of the present invention. Furthermore, the number average molecular weight (Mn) of the polymer of the present invention is preferably 500 to 10,000,000, more preferably 1,000 to 5,000,000, and even more preferably 10,000 to 1,000,000, for reasons of better effects of the present invention. The polydispersity (Mw / Mn) (PDI) of the polymer of the present invention is preferably 1.0 to 3.0, more preferably 1.0 to 2.0, and even more preferably 1.0 to 1.5, for reasons of better effects of the present invention. In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) are values ​​calculated as standard polystyrene obtained by gel permeation chromatography (GPC) measurement under the following conditions. Solvent: Tetrahydrofuran Detector: RI detector

[0034] [2] Manufacturing method The method for producing the polymer of the present invention is not particularly limited, but when the specific functional group is a functional group having a (silyl) ester of a carboxy group and an alkoxysilyl group, the following production method 1 is preferred because the effects of the present invention are more excellent for the resulting polymer of the present invention, and when the specific functional group is a functional group having a carboxy group and an alkoxysilyl group, the following production method 2 is preferred because the effects of the present invention are more excellent for the resulting polymer of the present invention. Hereinafter, the expression "the effects of the present invention are more excellent" will also be simply referred to as "the effects of the present invention are more excellent" for the resulting polymer of the present invention.

[0035] [Manufacturing method 1] Manufacturing method 1 is a polymerization step of polymerizing a diene-containing monomer by anionic polymerization to obtain a diene-based polymer having an active terminal; and a terminal modification step of reacting the diene polymer having an active terminal obtained in the polymerization step with a compound having a (silyl) ester of a carboxy group and an alkoxysilyl group to obtain a terminal-modified diene polymer, which is a diene polymer having a functional group having a (silyl) ester of a carboxy group and an alkoxysilyl group at its terminal. A method for producing a terminally modified diene polymer.

[0036] Each step will be described in detail below.

[0037] [Polymerization process] The polymerization step is a step in which a diene-based polymer having an active terminal (anionic species) is obtained by polymerizing a diene-containing monomer by anionic polymerization.

[0038] <Monomer> Specific examples and preferred embodiments of the diene-containing monomer used in the polymerization step are the same as those of the skeleton of the polymer of the present invention described above.

[0039] <Anionic polymerization> The anionic polymerization is not particularly limited, but anionic polymerization using an organolithium compound is preferred because it provides better effects of the present invention.

[0040] (organolithium compounds) The organolithium compound is not particularly limited, and specific examples thereof include monoorganolithium compounds such as n-butyllithium (n-BuLi), sec-butyllithium, tert-butyllithium, n-propyllithium, isopropyllithium, and benzyllithium; and polyfunctional organolithium compounds such as 1,4-dilithiobutane, 1,5-dilithiopentane, 1,6-dilithiohexane, 1,10-dilithiodecane, 1,1-dilithiodiphenylene, dilithiopolybutadiene, dilithiopolyisoprene, 1,4-dilithiobenzene, 1,2-dilithio-1,2-diphenylethane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-tirithiobenzene, and 1,3,5-tirithio-2,4,6-triethylbenzene. Among these, the monoorganolithium compounds n-butyllithium, sec-butyllithium, and tert-butyllithium are preferred, and n-butyllithium is more preferred, due to the superior effects of the present invention.

[0041] The amount of the organolithium compound used is not particularly limited, but is preferably 0.001 to 10 mol % relative to the monomer, because this provides a better effect of the present invention.

[0042] <Diene polymer with active terminal> The preferred range of the molecular weight of the diene polymer having an active terminal obtained in the polymerization step is the same as that of the polymer of the present invention described above.

[0043] [Terminal modification step] The terminal modification step is a step of reacting the diene polymer having an active terminal obtained in the polymerization step described above with a compound having a (silyl) ester of a carboxy group and an alkoxysilyl group (hereinafter also referred to as a "specific modifying agent") to obtain a terminal-modified diene polymer, which is a diene polymer having a functional group having a (silyl) ester of a carboxy group and an alkoxysilyl group at its terminal.

[0044] <Specific denaturant> The specific modifying agent is a compound having a (silyl) ester of a carboxy group and an alkoxysilyl group. The definition, specific examples and preferred embodiments of the (silyl) ester of the carboxy group are the same as those of the specific functional group of the polymer of the present invention described above. The definition, specific examples and preferred embodiments of the alkoxysilyl group are the same as those of the specific functional group of the polymer of the present invention described above.

[0045] (Preferred embodiment) The specific modifying agent is preferably a compound represented by the following formula (III) because the effects of the present invention are more excellent.

[0046] [ka]

[0047] In the above formula (III), R 1 and R 2 each independently represents an alkyl group having 1 to 10 carbon atoms or a phenyl group, n represents an integer of 0 to 2, R 3 represents an alkylene group having 1 to 10 carbon atoms which may contain an oxygen atom, or an aromatic ring; R 4 and R 5 each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, A represents a carbon atom or a silicon atom, and R 6 represents an alkyl group having 1 to 10 carbon atoms.

[0048] R in the above formula (III) 1 Specific examples and preferred embodiments of each symbol (except for n) are the same as those in formula (I) above. The above n is preferably an integer of 0 to 1, and more preferably 0, because the effects of the present invention are more excellent.

[0049] [Manufacturing method 2] Manufacturing method 2 is This is a method for producing a terminal-modified diene polymer, in which the terminal-modified diene polymer obtained by the above-mentioned Production Method 1 is hydrolyzed to obtain a terminal-modified diene polymer, which is a diene polymer having functional groups having a carboxy group and an alkoxysilyl group at its terminals. By hydrolyzing the terminally modified diene polymer obtained by Production Method 1, the (silyl) ester of the carboxy group of the specific functional group is hydrolyzed to a carboxy group. As a result, a terminally modified diene polymer is obtained, which is a diene polymer having a functional group having a carboxy group and an alkoxysilyl group at its terminal. Hereinafter, the step of hydrolyzing the terminally modified diene polymer obtained by Production Method 1 will also be referred to as the "hydrolysis step."

[0050] [3]Usage The polymers of the present invention are useful in compositions containing silica, particularly rubber compositions (for tires, conveyor belts, hoses, etc., particularly tires). [Example]

[0051] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. [Production of Diene Polymer] Terminally modified diene-based polymers 1 to 4, an unmodified diene-based polymer, and a comparative modified diene-based polymer 1 were produced as follows. Note that all of the terminally modified diene-based polymers 1 to 4 are diene-based polymers having a group represented by formula (II) (corresponding to a functional group (specific functional group) having a carboxy group and an alkoxysilyl group) at their terminals, and therefore correspond to the polymers of the present invention described above. On the other hand, unmodified diene polymers are not terminally modified and therefore do not fall under the category of the polymer of the present invention. Furthermore, the functional group at the terminal of comparative modified diene polymer 1 is a functional group that has an alkoxysilyl group but does not have a carboxy group or its (silyl) ester, and therefore does not fall under the category of a specific functional group, and therefore does not fall under the category of the polymer of the present invention described above.

[0052] <End-modified diene polymer 1> Terminally modified diene polymer 1 was produced as follows.

[0053] (Polymerization process) n-BuLi (Kanto Chemical, 1.56 mol / L (hexane solution), 1.5 mL, 2.43 mmol) was added to cyclohexane (Kanto Chemical, 7 mL) at room temperature. 1,3-Butadiene (TCI, 15% by mass (hexane solution), 52.9 g, 146.7 mmol) was added to the solution and stirred at room temperature for 24 hours. As a result, a butadiene polymer with active terminals was obtained.

[0054] (Terminal modification process) Next, triisopropylsilyl 3-triethoxysilyl-2-methylpropionate (a compound represented by the above formula (III), where R 1 is an ethyl group, n is 0, and R 3 is a methylene group, and R 4 is a hydrogen atom, and R 5 is a methyl group, A is a silicon atom, and R 6 The polymerization was terminated by adding 2.25 g (5.52 mmol) of specific modifier 1 (hereinafter referred to as "specific modifier 1"). The resulting polymer solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (400 mL) to separate the methanol-insoluble components.

[0055] As a result, the group represented by formula (I) (wherein, in formula (I), R 1 is an ethyl group, n is 0, and R 3 is a methylene group, and R 4 is a hydrogen atom, and R 5 is a methyl group, A is a silicon atom, and R 6 The butadiene polymer was obtained having terminal groups (wherein is an isopropyl group).

[0056] (Hydrolysis process) Furthermore, it is hydrolyzed by moisture in the air to form a group represented by formula (II) (wherein, in formula (II), R 1 is an ethyl group, n is 0, and R 3 is a methylene group, and R 4 is a hydrogen atom, and R 5 A butadiene polymer having terminal groups (wherein each group is a methyl group) was obtained in 87% yield (6.94 g, Mn=10,900, Mw=13,300, PDI=1.2). The obtained butadiene polymer is also called terminal-modified diene polymer 1.

[0057] <End-modified diene polymer 2> Terminally modified diene polymer 2 was produced as follows.

[0058] (Polymerization process) n-BuLi (Kanto Chemical, 1.56 mol / L (hexane solution), 1.5 mL, 2.43 mmol) was added to cyclohexane (Kanto Chemical, 7 mL) at room temperature. 1,3-Butadiene (TCI, 15% by mass (hexane solution), 50.6 g, 140.3 mmol) was added to the solution and stirred at room temperature for 24 hours. As a result, a butadiene polymer with active terminals was obtained.

[0059] (Terminal modification process) Next, triisopropylsilyl 3-methyldiethoxysilyl-2-methylpropionate (a compound represented by the above formula (III), where R 1 is an ethyl group, and R 2 is a methyl group, n is 1, and R 3 is a methylene group, and R 4 is a hydrogen atom, and R 5 is a methyl group, A is a silicon atom, and R 6 The polymerization was terminated by adding 2.10 g (5.75 mmol) of specific modifier 2 (hereinafter referred to as "specific modifier 2"). The resulting polymer solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (400 mL) to separate the methanol-insoluble components.

[0060] As a result, the group represented by formula (I) (wherein, in formula (I), R 1 is an ethyl group, and R 2 is a methyl group, n is 1, and R 3 is a methylene group, and R 4 is a hydrogen atom, and R 5 is a methyl group, A is a silicon atom, and R 6 The butadiene polymer was obtained having terminal groups (wherein is an isopropyl group).

[0061] (Hydrolysis process) Furthermore, it is hydrolyzed by moisture in the air to form a group represented by formula (II) (wherein, in formula (II), R 1 is an ethyl group, and R 2 is a methyl group, n is 1, and R 3 is a methylene group, and R 4 is a hydrogen atom, and R 5 A butadiene polymer having terminal groups (wherein each group is a methyl group) was obtained in 88% yield (6.71 g, Mn = 11,100, Mw = 14,200, PDI = 1.3). The obtained butadiene polymer is also called terminal-modified diene polymer 2.

[0062] <End-modified diene polymer 3> Terminally modified diene polymer 3 was produced as follows.

[0063] (Polymerization process) n-BuLi (Kanto Chemical, 1.56 mol / L (hexane solution), 18 mL, 28.1 mmol) was added to a cyclohexane (4.27 kg) solution of a mixture of 1,3-butadiene (665 g) and styrene (Kanto Chemical, 300 g), and the mixture was stirred at 60°C for 14 hours and cooled to room temperature. As a result, a butadiene-styrene copolymer with active terminals was obtained.

[0064] (Terminal modification process) Next, triisopropylsilyl 3-triethoxysilyl-2-methylpropionate (specific modifier 1) (20.54 g, 50.5 mmol) was added to terminate the polymerization. The resulting polymer solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (5 L) to separate the methanol-insoluble components.

[0065] As a result, the group represented by formula (I) (wherein, in formula (I), R 1 is an ethyl group, n is 0, and R 3 is a methylene group, and R 4 is a hydrogen atom, and R 5 is a methyl group, A is a silicon atom, and R 6 The butadiene-styrene copolymer was obtained with a terminal group (wherein is an isopropyl group).

[0066] (Hydrolysis process) Furthermore, it is hydrolyzed by moisture in the air to form a group represented by formula (II) (wherein, in formula (II), R 1 is an ethyl group, n is 0, and R 3 is a methylene group, and R 4 is a hydrogen atom, and R 5 A butadiene-styrene copolymer having terminal groups (wherein each represents a methyl group) was obtained in a yield of 85% (818 g, Mn=180,000, Mw=241,000, PDI=1.3, styrene content=31% by mass). The obtained butadiene-styrene copolymer is also referred to as terminal-modified diene polymer 3.

[0067] <End-modified diene polymer 4> Terminally modified diene polymer 4 was produced as follows.

[0068] (Polymerization process) n-BuLi (Kanto Chemical, 1.56 mol / L (hexane solution), 18 mL, 28.1 mmol) was added to a cyclohexane (4.27 kg) solution of a mixture of 1,3-butadiene (650 g) and styrene (Kanto Chemical, 300 g), and the mixture was stirred at 60°C for 14 hours and cooled to room temperature. As a result, a butadiene-styrene copolymer with active terminals was obtained.

[0069] (Terminal modification process) Next, 3-methyldiethoxysilyl-2-methylpropionate triisopropylsilyl (specific modifier 2) (20.28 g, 55.6 mmol) was added to terminate the polymerization. The resulting polymer solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (5 L) to separate the methanol-insoluble components.

[0070] As a result, the group represented by formula (I) (wherein, in formula (I), R 1 is an ethyl group, and R 2 is a methyl group, n is 1, and R 3 is a methylene group, and R 4 is a hydrogen atom, and R 5 is a methyl group, A is a silicon atom, and R 6 The butadiene-styrene copolymer was obtained with a terminal group (wherein is an isopropyl group).

[0071] (Hydrolysis process) Furthermore, it is hydrolyzed by moisture in the air to form a group represented by formula (II) (wherein, in formula (II), R 1 is an ethyl group, and R 2 is a methyl group, n is 1, and R 3 is a methylene group, and R 4 is a hydrogen atom, and R 5 A butadiene-styrene copolymer having terminal groups (wherein each represents a methyl group) was obtained in an 85% yield (805 g, Mn=202,000, Mw=256,000, PDI=1.3, styrene content=32% by mass). The obtained butadiene-styrene copolymer is also referred to as terminal-modified diene polymer 4.

[0072] <End-modified diene polymer 5> A butadiene polymer was obtained in the same manner as in the above-mentioned terminally modified diene polymer 1, except that the amount of n-BuLi was changed. The obtained butadiene polymer contains a group represented by formula (II) (wherein, in formula (II), R 1is an ethyl group, n is 0, and R 3 is a methylene group, and R 4 is a hydrogen atom, and R 5 The butadiene polymer (Mn=39,800, Mw=42,000, PDI=1.1) had terminal groups (Mn=39,800, Mw=42,000, PDI=1.1). The butadiene polymer obtained is also referred to as terminal-modified diene-based polymer 5. 1 The H-NMR spectrum is shown in Figure 1. In Figure 1, Et represents an ethyl group.

[0073] <Unmodified diene polymer> A butadiene polymer was obtained in the same manner as in the above-mentioned terminal-modified diene-based polymer 1, except that the polymerization was terminated by adding methanol instead of specific modifying agent 1. The butadiene polymer obtained was a butadiene polymer (Mn=12,400, Mw=14,600, PDI=1.2) with no modified terminals. The butadiene polymer obtained is also called an unmodified diene polymer.

[0074] <Comparative modified diene polymer 1> A butadiene polymer was obtained in the same manner as in the above-described terminal-modified diene-based polymer 1, except that the polymerization was terminated by adding methyltriethoxysilane (hereinafter also referred to as "comparative modifier 1") instead of specific modifier 1. The butadiene polymer obtained was a butadiene polymer (Mn=13,200, Mw=14,900, PDI=1.1) having a methyldiethoxysilyl group at the end. The butadiene polymer obtained is also referred to as comparative modified diene polymer 1.

[0075] [Evaluation of silica adsorption] Each of the obtained diene polymers was dissolved in xylene. Silica was added to the obtained solution, and the mixture was heated and stirred. The insoluble matter (silica and the diene polymer adsorbed on the silica) was then separated by filtration, washed with THF (tetrahydrofuran), and recovered as the insoluble matter. The silica adsorption rate was then calculated as follows. The results are shown in Table 1. A higher silica adsorption rate indicates better silica adsorption. Adsorption rate = (mass of insoluble matter - mass of silica) / (mass of dissolved diene polymer)

[0076] [Table 1]

[0077] As can be seen from Table 1, compared to the unmodified diene-based polymer (Comparative Example 1) not having a specific functional group at its terminal and the comparative modified diene-based polymer 1 (Comparative Example 2), the terminal-modified diene-based polymers 1 to 5 (Examples 1 to 5) having a specific functional group at their terminals showed excellent silica adsorption properties.

Claims

1. a diene-based polymer having, at its terminal, a functional group having a carboxy group or an alkyl ester or silyl ester thereof and an alkoxysilyl group; The functional group is a group represented by the following formula (I) or a group represented by the following formula (II). 【Chemical 1】 In formula (I), R 1 and R 2 each independently represent an alkyl group having 1 to 10 carbon atoms or a phenyl group, n represents 0, R 3 represents an alkylene group having 1 to 10 carbon atoms which may contain an oxygen atom or an aromatic ring, R 4 and R 5 each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, A represents a carbon atom or a silicon atom, and R 6 represents an alkyl group having 1 to 10 carbon atoms. 【Chemistry 2】 In formula (II), R 1 and R 2 each independently represent an alkyl group having 1 to 10 carbon atoms or a phenyl group; n represents 0; R 3 represents an alkylene group having 1 to 10 carbon atoms which may contain an oxygen atom or an aromatic ring; and R 4 and R 5 each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

2. The terminally modified diene polymer according to claim 1, wherein A in formula (I) is a silicon atom.

3. 3. The terminally modified diene polymer according to claim 1, which has a weight average molecular weight of 1,000 to 10,000,000.

4. 4. The terminal-modified diene polymer according to claim 1, wherein the diene that constitutes the repeating unit of the diene polymer is 1,3-butadiene or isoprene.

5. 5. The terminal-modified diene polymer according to claim 1, wherein the monomer that constitutes the repeating unit of the diene polymer contains an aromatic vinyl as a monomer other than the diene.

6. A rubber composition containing a terminally modified diene-based polymer described in any one of claims 1 to 5 and silica.

7. a polymerization step of polymerizing a diene-containing monomer by anionic polymerization to obtain a diene-based polymer having an active terminal; a terminal modification step of reacting the diene polymer having an active terminal obtained in the polymerization step with a compound having an alkyl ester or silyl ester of a carboxy group and an alkoxysilyl group to obtain a terminal-modified diene polymer, which is a diene polymer having a functional group having an alkyl ester or silyl ester of a carboxy group and an alkoxysilyl group at its terminal; The method for producing a terminal-modified diene-based polymer, wherein the compound is a compound represented by the following formula (III): 【Chemistry 3】 In formula (III), R 1 and R 2 each independently represent an alkyl group having 1 to 10 carbon atoms or a phenyl group, n represents 0, R 3 represents an alkylene group having 1 to 10 carbon atoms which may contain an oxygen atom or an aromatic ring, R 4 and R 5 each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, A represents a carbon atom or a silicon atom, and R 6 represents an alkyl group having 1 to 10 carbon atoms.

8. The method for producing a terminally modified diene polymer according to claim 7, wherein A in formula (III) is a silicon atom.

9. A method for producing a terminal-modified diene-based polymer, comprising hydrolyzing a terminal-modified diene-based polymer obtained by the production method according to claim 7 or 8 to obtain a terminal-modified diene-based polymer, which is a diene-based polymer having functional groups having a carboxy group and an alkoxysilyl group at its terminals.

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