Modified diene-based polymer and rubber composition

Abstract

To provide a rubber composition and a modified diene-based polymer which exhibit excellent fuel economy performance in the cured state.SOLUTION: The present invention provides: a modified diene-based polymer comprising a functional group derived from a modifying agent represented by the following formula (1) and having a weight-average molecular weight of 500 to 80,000 g / mol; a rubber composition comprising a rubber component having a weight-average molecular weight of 100,000 g / mol or more, silica, and the modified diene-based polymer; and a tire produced using the rubber composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a modified diene-based polymer and a rubber composition. [Background technology]

[0002] 2. Description of the Related Art Conventionally, rubber compositions for tires containing a diene rubber, silica, and a low molecular weight conjugated diene polymer having a weight average molecular weight of 2,000 to 50,000 have been known (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-47888 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have studied the rubber composition containing a low molecular weight conjugated diene polymer, etc., disclosed in Patent Document 1, and have found that the fuel economy of the cured product obtained from such a rubber composition may be poor in some cases.

[0005] Therefore, an object of the present invention is to provide a rubber composition that exhibits excellent fuel economy when cured. Another object of the present invention is to provide a modified diene polymer capable of realizing the above-mentioned rubber composition. [Means for solving the problem]

[0006] As a result of intensive research into solving the above problems, the present inventors have found that the problems can be solved by the following configuration.

[0007] [1] A modified diene polymer having a functional group derived from a modifying agent represented by the following formula (1) and having a weight average molecular weight of 500 to 80,000 g / mol: [ka] In formula (1), R 1 ~R 2 one of which is an alkoxy group and the other is an alkoxy group or an alkyl group; R 3 ~R 4 one of which is an alkoxy group and the other is an alkoxy group or an alkyl group; R 5 is an alkylene group. [2] The modified diene polymer according to [1], wherein the main chain is polybutadiene, polyisoprene, or a styrene-butadiene copolymer. [3] The modified diene polymer according to [1] or [2], which has a molecular weight distribution of 1.0 to 2.0. [4] A rubber composition comprising a rubber component having a weight average molecular weight of 100,000 g / mol or more, silica, and the modified diene polymer according to any one of [1] to [3]. [5] The rubber composition according to [4], wherein the amount of the modified diene polymer is 20 parts by mass or less per 100 parts by mass of the rubber component. [6] A tire manufactured using the rubber composition according to [4] or [5]. Effect of the Invention

[0008] According to the present invention, it is possible to provide a rubber composition that exhibits excellent fuel economy when cured. The present invention also provides a modified diene polymer capable of realizing the above-mentioned rubber composition. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a partial cross-sectional schematic view of a tire showing one example of an embodiment of the tire of the present invention. [Diagram 2] FIG. 2 is a 1H-NMR chart of Example 1 (modified liquid BR1). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in detail below. The following description of the configuration may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment.

[0011] In this specification, a numerical range expressed using "~" means a range including the numerical values ​​written before and after "~". In the present specification, each component may be used alone or in combination of two or more kinds. In this specification, when two or more types of a component are used in combination, the "content" of the component means the total content of those two or more types, unless otherwise specified. In the present specification, the method for producing each component is not particularly limited unless otherwise specified. For example, a conventionally known method may be used.

[0012] [Modified diene polymer] The modified diene polymer of the present invention will be described in detail below. The modified diene polymer of the present invention (polymer of the present invention) is a modified diene polymer having a functional group derived from a modifying agent represented by the following formula (1) and having a weight average molecular weight of 500 to 80,000 g / mol. [ka] In formula (1), R 1 ~R 2 one of which is an alkoxy group and the other is an alkoxy group or an alkyl group; R 3 ~R 4 one of which is an alkoxy group and the other is an alkoxy group or an alkyl group; R 5 is an alkylene group.

[0013] The reason why the polymer of the present invention can solve the problems of the present invention is not necessarily clear, but the present inventors speculate as follows. The mechanism by which the effects are obtained is not limited by the following speculation. In other words, even if the effects are obtained by a mechanism other than the following, it is included in the scope of the present invention. It has been confirmed that the polymer of the present invention has a higher silica adsorption property than an unmodified low-molecular-weight diene polymer because it has a functional group derived from the modifying agent represented by formula (1). In addition, when the same amount of the polymer of the present invention or a modified diene-based polymer having a higher molecular weight than the polymer of the present invention and the same number of modifying groups per molecule as the polymer of the present invention is used in a rubber composition, the polymer of the present invention has a weight average molecular weight of 500 to 80,000 g / mol, and therefore can introduce more of the functional groups into the rubber composition than when a modified diene-based polymer having a higher molecular weight is used. As described above, the polymer of the present invention has excellent silica adsorption properties and, due to its low molecular weight, allows the introduction of a large amount of functional groups. Therefore, it is presumed that the polymer of the present invention can provide a rubber composition that, when cured, has excellent fuel economy.

[0014] (There are impossible and impractical circumstances regarding the specification that the polymer of the present invention "has a functional group derived from the modifying agent represented by formula (1).") In addition, the polymer of the present invention is considered to have a functional group derived from the modifying agent represented by formula (1), but since the modifying agent has two 1-aza-2-silacyclopentane rings and the modification reaction by the modifying agent is complicated, the polymer of the present invention is diverse, and it is impossible or almost impractical to specify the specific structure of the functional group possessed by the polymer of the present invention and the polymer of the present invention. Therefore, it is considered that there are impossible or impractical circumstances regarding the specification that the polymer of the present invention "has a functional group derived from the modifying agent represented by formula (1)".

[0015] [Modifier represented by formula (1)] The polymer of the present invention has a functional group derived from a modifying agent (specific modifying agent) represented by the following formula (1). [ka] In formula (1), R 1 ~R 2 one of which is an alkoxy group and the other is an alkoxy group or an alkyl group; R 3 ~R 4 one of which is an alkoxy group and the other is an alkoxy group or an alkyl group; R 5 is an alkylene group.

[0016] [R 1 ~R 4 ] In formula (1), R 1 ~R 2 One of the groups is an alkoxy group, and the remaining group is an alkoxy group or an alkyl group. In addition, in formula (1), R 3 ~R 4 One of the groups is an alkoxy group, and the remaining group is an alkoxy group or an alkyl group.

[0017] (alkoxy group) R 1 ~R 2 The alkoxy group as one of the groups includes, for example, an alkoxy group having 1 to 10 carbon atoms, and specific examples thereof include a methoxy group, an ethoxy group, a pentyloxy group, and an octyloxy group. R 3 ~R 4 The same applies to the alkoxy group as one of the groups. Also, R 1 ~R 2 an alkoxy group when the remaining one of the groups is an alkoxy group; R 3 ~R 4 The same applies to the alkoxy group when the remaining one of the groups is an alkoxy group.

[0018] (Alkyl group) R 1 ~R 2When the remaining one of the above is an alkyl group, examples of the alkyl group include alkyl groups having 1 to 10 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a pentyl group, and an octyl group. R 3 ~R 4 The same applies to the alkyl group when the remaining one of the groups is an alkyl group.

[0019] (R 1 ~R 4 (Combination of R in formula (1) 1 ~R 4 From the viewpoint that the effect of the present invention (low fuel consumption, the same applies below) is more excellent, the combination of R 1 ~R 4 are preferably all alkoxy groups, 1 ~R 4 It is more preferable that all of the groups are methoxy groups.

[0020] [R 5 ] In formula (1), R 5 is an alkylene group (a divalent linear or branched aliphatic hydrocarbon group). Examples of the alkylene group include alkylene groups having 1 to 10 carbon atoms, and specific examples include a methylene group, an ethylene group, a trimethylene group, and a hexamethylene group. R 5 From the viewpoint of achieving superior effects of the present invention, is preferably an alkylene group having 2 to 4 carbon atoms, and more preferably a trimethylene group.

[0021] (Method for preparing specific denaturant) As a method for preparing the specific modifier, for example, a method for preparing a compound represented by the formula A: Si(-R 1 )(-R 2 )(-R 6 )-(CH 2 ) 3 -NH-R 5 -NH-(CH 2 ) 3 -Si(-R 3 )(-R 4)(-R 7 A method of obtaining a specific modifier is to add a catalyst to a compound represented by the formula A, stir and heat the mixture at 80 to 110°C, and remove the generated alcohol from the reaction system while carrying out a cyclization reaction. 1 )(-R 2 )(-R 6 )-(CH 2 ) 3 -NH- and -NH-(CH 2 ) 3 -Si(-R 3 )(-R 4 )(-R 7 ) can each be cyclized to form two 1-aza-2-silacyclopentane rings in formula (1). After the reaction, the specific modifying agent may be purified, for example, by passing the reaction solution through a flash column.

[0022] A compound represented by formula A In the above formula A, "Si(-R 1 )(-R 2 )(-R 6 )" is Si, -R 1 , -R 2 , and -R 6 "Si(-R 3 )(-R 4 )(-R 7 )" is also the same. R in the above formula A 1 ~R 5 is R in formula (1). 1 ~R 5 is the same as: R in the above formula A 6 ~R 7 R each independently represents an alkoxy group. 6 ~R 7 The alkoxy group represented by R 1 ~R 2 The alkoxy group may be the same as one of the groups. Examples of the compound represented by the above formula A include N,N'-bis(3-trialkoxysilylpropyl)-1,3-propyldiamine, N,N'-bis(3-dialkoxyalkylsilylpropyl)-1,3-propyldiamine, Examples thereof include N-(3-trialkoxysilylpropyl)-N'-(3-dialkoxyalkylsilylpropyl)-1,3-propyldiamine. A specific example of the N,N'-bis(3-trialkoxysilylpropyl)-1,3-propyldiamine is N,N'-bis(3-trimethoxysilylpropyl)-1,3-propyldiamine.

[0023] ·catalyst Examples of the catalyst that can be used in the cyclization reaction include ammonium salts such as ammonium chloride and ammonium sulfate. The amount of the catalyst used is not particularly limited, but may be, for example, 0.1 to 10 mass % of the amount of the compound represented by formula A used.

[0024] [Main chain] The modified diene polymer of the present invention has a main chain as a portion other than the functional group derived from the specific modifier. In this specification, the main chain refers to the diene rubber portion (the portion other than the functional group derived from the specific modifier) ​​in the modified diene polymer of the present invention.

[0025] (Diene Monomer) In the modified diene polymer of the present invention, the main chain has a repeating unit formed by a monomer containing a diene monomer. Examples of diene monomers include conjugated dienes such as butadiene (e.g., 1,3-butadiene), isoprene, chloroprene, etc. Among these, 1,3-butadiene and isoprene are preferable. The proportion (content) of the total amount of diene monomers in all monomers used to form the main chain is not particularly limited, but is preferably 10 to 100 mol %.

[0026] The above monomers may further include monomers other than diene monomers (other monomers). Examples of the other monomers include aromatic vinyls. Examples of aromatic vinyls include styrene, α-methylstyrene, and 4-methylstyrene. The ratio (content) of the total amount of other monomers (for example, aromatic vinyl) in all monomers used to form the main chain is not particularly limited, but can be 0 to 90 mol %. In this specification, the proportion of the total amount of diene monomers in the total monomers can be reflected in the proportion (mol%) of all repeating units derived from diene monomers in all repeating units of the diene rubber portion as the main chain of the modified diene polymer of the present invention. The same applies to the proportion of the total amount of other monomers in the total monomers.

[0027] From the viewpoint of achieving superior effects of the present invention, the main chain of the modified diene polymer of the present invention is preferably polybutadiene, polyisoprene, or a styrene-butadiene copolymer, and more preferably polybutadiene. The polyisoprene as the main chain may be either synthetic polyisoprene or natural rubber. From the viewpoint of facilitating the introduction of a functional group derived from a specific modifier into the terminal or inside of the polymer of the present invention, one of the preferred embodiments of the main chain of the polymer of the present invention is a synthetic rubber formed from a monomer containing a diene monomer.

[0028] [Functional group] (Position of functional group) In the polymer of the present invention, the position of the functional group is not particularly limited. In the polymer of the present invention, any repeating unit among all repeating units constituting the main chain (diene rubber) of the polymer of the present invention may have the functional group. The position of the functional group in the polymer of the present invention may be, for example, the terminal, side chain, or inside of the polymer of the present invention, or a combination thereof. When the polymer of the present invention has the above-mentioned functional group at a terminal, the polymer of the present invention may have the above-mentioned functional group at only one of a plurality of terminals, or at a plurality of terminals. In one preferred embodiment, the polymer of the present invention has a functional group derived from a specific modifying agent, for example, at the terminal and / or inside of the polymer of the present invention.

[0029] ·Terminal When the polymer of the present invention has a functional group derived from a specific modifying agent at the end of the polymer of the present invention, the functional group derived from the specific modifying agent can be bonded directly or via a linking group to at least one of the ends of the main chain of the polymer of the present invention. The linking group is not particularly limited. In the above case, the functional group derived from the specific modifying agent can have a structure in which one of the two 1-aza-2-silacyclopentane rings in the specific modifying agent is opened and the remaining one remains as a 1-aza-2-silacyclopentane ring. The above-mentioned opened 1-aza-2-silacyclopentane ring can be bonded to the main chain as described above. A specific example of the polymer of the present invention having a functional group derived from a specific modifying agent at an end of the polymer of the present invention is, for example, when the polymer of the present invention is linear (for example, when the main chain of the polymer of the present invention is linear), a specific example of the polymer of the present invention having one functional group derived from a specific modifying agent at one end of the polymer of the present invention.

[0030] ·internal An example of a case in which the polymer of the present invention has a functional group derived from a specific modifying agent inside the polymer of the present invention is a case in which two main chains of the polymer of the present invention are bonded to the functional group via a functional group derived from one specific modifying agent. In the above case, the functional group derived from the specific modifier can have a structure in which both of the two 1-aza-2-silacyclopentane rings in the specific modifier are opened. Each of the opened 1-aza-2-silacyclopentane rings in the functional group can be bonded to one main chain (diene rubber). The functional group and the main chain (diene rubber) can be bonded directly or via a linking group. The linking group is not particularly limited.

[0031] In the polymer of the present invention, the functional group can be bonded to the main chain of the polymer of the present invention (preferably to the terminal or inside of the polymer of the present invention) directly or via a linking group. The linking group is not particularly limited.

[0032] (Specific examples of functional groups) Examples of the functional group contained in the polymer of the present invention include groups represented by the following formulas (2) to (3). The group represented by formula (2) is as follows. [ka] In formula (2), R 1 ~R 5 is R in Eq. (1). 1 ~R 5 The symbol * indicates the bonding position with the main chain (diene rubber). The polymer of the present invention may have a functional group represented by formula (2), for example, at the end or in the side chain of the polymer of the present invention. In one preferred embodiment of the polymer of the present invention, the polymer has a functional group represented by formula (2) at the terminal thereof.

[0033] The group represented by formula (3) is as follows. [ka] In formula (3), R 1 ~R 5 is R in Eq. (1). 1 ~R 5 The symbol * indicates the bonding position with the main chain (diene rubber). The polymer of the present invention may have, for example, a functional group represented by formula (2) inside the polymer of the present invention. When the polymer of the present invention has a functional group represented by formula (2) inside the polymer of the present invention, the polymer may have the above diene rubber (main chain) on both sides of the functional group represented by formula (2).

[0034] (Number of functional groups) The number of functional groups that the polymer of the present invention has per molecule may be at least 1. The upper limit of the number of functional groups that the polymer of the present invention has per molecule is not particularly limited, but may be, for example, 5 or less. In one preferred embodiment of the polymer of the present invention, for example, one molecule of the polymer of the present invention has one of the above functional groups.

[0035] [Weight average molecular weight] The polymer of the present invention has a weight average molecular weight of 500 to 80,000 g / mol. From the viewpoint of achieving superior effects of the present invention and superior silica adsorption, the weight average molecular weight is preferably 5,000 to 30,000 g / mol. In the present invention, the number average molecular weight (Mn), weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) are values ​​calculated as standard polystyrene by gel permeation chromatography (GPC) measurement under the following conditions. Solvent: Tetrahydrofuran Detector: RI detector

[0036] (molecular weight distribution) The molecular weight distribution (Mw / Mn) of the polymer of the present invention is preferably from 1.0 to 2.0, and more preferably from 1.0 to 1.3, from the viewpoints of achieving better effects of the present invention and excellent silica adsorption.

[0037] (Production method of the polymer of the present invention) An example of a method for producing the polymer of the present invention is a method for producing a modified diene polymer by polymerizing monomers including at least a diene monomer using an organolithium compound (monomer polymerization step) and then terminating the polymerization using a specific modifying agent (polymerization terminating step).

[0038] (Monomer polymerization process) Monomers containing diene monomers The monomer containing a diene monomer used in the monomer polymerization step can be the same as the above-mentioned monomer containing a diene monomer that forms the repeating unit contained in the main chain of the polymer of the present invention.

[0039] Organolithium compounds The organolithium compounds used in the monomer polymerization step can function as initiators. Examples of the organolithium compound include mono-organolithium compounds such as n-butyllithium, 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-trilithiobenzene, and 1,3,5-trilithio-2,4,6-triethylbenzene. In particular, the mono-organolithium compounds of n-butyllithium, sec-butyllithium, and tert-butyllithium are preferred.

[0040] The amount of the organolithium compound is not particularly limited, but is preferably 0.001 to 10 mol % based on the total amount of the monomers to be polymerized.

[0041] - Polymerization method of monomer The method for polymerizing the monomer is not particularly limited, but examples include a method in which the monomer is added to an organic solvent solution containing the organolithium compound described above, and the mixture is stirred at a temperature range of 0 to 120°C (preferably 20 to 100°C). Examples of organic solvents that can be used during polymerization of the monomers include cycloalkane solvents such as cyclohexane, chain alkane solvents such as hexane, ethers such as tetrahydrofuran (THF), and aromatic solvents such as toluene.

[0042] When polymerizing the monomer, for example, 2,2-di(2-tetrahydrofuryl)propane may be further added to the polymerization system (for example, the organic solvent solution containing the above-mentioned organolithium compound and monomer) in order to increase the polarity in the polymerization system and facilitate the progress of the polymerization.

[0043] When 2,2-di(2-tetrahydrofuryl)propane is further added to the polymerization system, the amount of 2,2-di(2-tetrahydrofuryl)propane is not particularly limited, but is preferably 0.01 to 90 mol %, more preferably 0.1 to 80 mol %, and even more preferably 1 to 20 mol %, based on the organolithium compound. In the monomer polymerization step, a raw diene polymer (an unmodified diene polymer, which corresponds to the main chain portion of the polymer of the present invention) can be obtained.

[0044] (Polymerization stop step) After the monomer polymerization step, the polymerization is terminated using a specific modifying agent in the polymerization termination step, whereby the modified diene polymer of the present invention can be obtained. In the polymerization termination step, the starting diene polymer obtained in the monomer polymerization step is reacted with a specific modifying agent to terminate the polymerization of the starting diene polymer and modify the starting diene polymer with the specific modifying agent. When the raw diene polymer obtained in the monomer polymerization step has an anion active species (when an organolithium compound is used as an initiator, the raw diene polymer can have an anion active species at the growth end), the specific modifier can function as an electrophile for the raw diene polymer obtained in the monomer polymerization step. That is, when the raw diene polymer has an anion active species, the anion attacks the silicon atom in the specific modifier and opens the 1-aza-2-silacyclopentane ring, so that the polymer of the present invention can have a modifying group derived from the specific modifier. It is considered that the polymer of the present invention can have, for example, a functional group represented by the above formula (2) or formula (3) as a modifying group derived from the above specific modifier. In the reaction between the starting diene polymer and the specific modifier, it is believed that the active anion species of the starting diene polymer and the 1-aza-2-silacyclopentane ring of the specific modifier can react in a molar ratio of 1:1. Furthermore, when the active anionic species contained in the starting diene polymer reacts with the specific modifying agent in a molar ratio of, for example, 1:1, the polymer of the present invention can have a functional group represented by formula (2). When the anionic active species of the raw diene polymer reacts with the specific modifying agent in a molar ratio of more than 1:1, the polymer of the present invention can be obtained, for example, as a mixture of a modified diene polymer having a functional group represented by formula (2) and a modified diene polymer having a functional group represented by formula (3).

[0045] Special modifier The specific modifying agent used in the polymerization termination step is the same as the modifying agent described above in [Modifying agent represented by formula (1)]. The specific modifying agent can form a functional group that the polymer of the present invention has. For reasons of superior effects of the present invention and superior silica adsorption, the ratio of the specific modifier to the organolithium compound (specific modifier / organolithium compound) is preferably 0.1 to 10, more preferably 0.6 to 5, in molar ratio.

[0046] - Polymerization termination In the polymerization terminating step, the method for terminating the polymerization is not particularly limited as long as a specific denaturing agent is used, and examples thereof include a method of adding a specific denaturing agent to a polymerization solution. By terminating the polymerization with the specific modifying agent, the starting diene polymer is modified with the specific modifying agent, and the modified diene polymer of the present invention can be obtained. After the polymerization is terminated, the reaction solution may be added to a large amount of alcohol such as methanol, and the ethanol-insoluble components may be separated, purified, and dried to purify the modified diene polymer of the present invention.

[0047] In one preferred embodiment, the polymer of the present invention is in a liquid state at 25°C.

[0048] As described above, examples of the polymer of the present invention include modified diene rubbers having a functional group derived from a specific modifier at least at one of the terminal, side chain, and internal positions. The polymer of the present invention may contain a modified diene rubber having a functional group derived from a specific modifier at at least one of the terminal, side chain, and internal positions, either alone or in combination. The polymer of the present invention may further contain unreacted raw diene polymer.

[0049] (Application) The polymer of the present invention can be widely used in rubber products such as tires, conveyor belts, hoses, etc. Among them, it is useful for tires. The polymers of the present invention are also useful in rubber compositions containing silica.

[0050] [Rubber composition] The rubber composition of the present invention will now be described. The rubber composition of the present invention is a rubber composition containing a rubber component having a weight average molecular weight of 100,000 g / mol or more, silica, and the modified diene-based polymer of the present invention.

[0051] [Rubber component] The rubber composition of the present invention contains a rubber component having a weight average molecular weight (Mw) of 100,000 g / mol or more. The method for measuring the weight average molecular weight of the rubber component is the same as described above. The rubber component does not contain the modified diene polymer of the present invention.

[0052] The upper limit of the weight average molecular weight (Mw) of the rubber component contained in the rubber composition of the present invention is not particularly limited, and can be, for example, 3,000,000 g / mol or less.

[0053] Examples of the rubber component include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), and chloroprene rubber (CR). From the viewpoint of obtaining superior effects of the present invention, the rubber component preferably contains at least one rubber selected from the group consisting of natural rubber, isoprene rubber, butadiene rubber, and styrene-butadiene rubber. When the rubber component contains butadiene rubber and styrene-butadiene rubber, from the viewpoint of obtaining better effects of the present invention, it is preferable that the content of the butadiene rubber is more than 0 mass% and not more than 50 mass% of the total amount of the rubber component, and the content of the styrene-butadiene rubber is 50 mass% or more and less than 100 mass% of the total amount of the rubber component.

[0054] [silica] The rubber composition of the present invention contains silica. The silica is not particularly limited, and any conventionally known silica can be used. Examples of the silica include wet silica, dry silica, fumed silica, and diatomaceous earth.

[0055] (CTAB) The cetyltrimethylammonium bromide (CTAB) adsorption specific surface area of ​​the silica (hereinafter, the "CTAB adsorption specific surface area" may be simply referred to as "CTAB") is not particularly limited. However, in order to improve the effect of the present invention, it is preferable that the cetyltrimethylammonium bromide (CTAB) adsorption specific surface area is 100 to 300 m 2 / g, and 150 to 200m 2 It is more preferable that the molecular weight is / g. Here, the CTAB adsorption specific surface area is a value obtained by measuring the amount of CTAB adsorbed on the silica surface in accordance with JIS K6217-3:2001 "Part 3: Determination of specific surface area - CTAB adsorption method."

[0056] (Content) The content of silica is preferably 5 to 200 parts by mass, more preferably 10 to 150 parts by mass, and further preferably 30 to 100 parts by mass, per 100 parts by mass of the rubber component, because the effects of the present invention are superior.

[0057] [Modified diene polymer] The rubber composition of the present invention contains the modified diene polymer of the present invention. The modified diene polymer contained in the rubber composition of the present invention is the modified diene polymer of the present invention described above. In the rubber composition of the present invention, the modified diene polymer is believed to function as a silica dispersant.

[0058] (Content) In the present invention, the content of the modified diene polymer may be more than 0 part by mass based on 100 parts by mass of the rubber component. The content of the modified diene polymer is preferably 20 parts by mass or less, and more preferably 5 to 15 parts by mass, per 100 parts by mass of the rubber component, because the effects of the present invention are more excellent.

[0059] Moreover, the content of the modified diene polymer is preferably 1 to 20 mass %, more preferably 5 to 15 mass %, relative to the above-mentioned silica content, because the effects of the present invention are more excellent.

[0060] [Optional ingredients] The rubber composition of the present invention may contain components (optional components) other than the above-mentioned components, as necessary. Examples of such components include various additives commonly used in rubber compositions, such as fillers other than silica (e.g., carbon black), silane coupling agents, terpene resins (e.g., aromatic modified terpene resins), thermally expandable microcapsules, zinc oxide (zinc white), stearic acid, antioxidants, waxes, processing aids, oils, liquid polymers (however, liquid polymers excluding the polymers of the present invention that are in a liquid state), thermosetting resins, vulcanizing agents (e.g., sulfur), vulcanization accelerators (accelerators), and vulcanization activators.

[0061] (Silane coupling agent) The rubber composition of the present invention preferably further contains a silane coupling agent because the effects of the present invention are more excellent. The silane coupling agent is not particularly limited as long as it is a silane compound having a hydrolyzable group and an organic functional group. The silane coupling agent is preferably a sulfur-containing silane coupling agent because the effects of the present invention are more excellent. Examples of sulfur-containing silane coupling agents include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide, triethoxysilylpropyl-methacrylate-monosulfide, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, and 3-octanoylthio-1-propyltriethoxysilane. In the rubber composition of the present invention, the content of the silane coupling agent is not particularly limited, but because the effects of the present invention are more excellent, the content is preferably 1 to 20 parts by mass, and more preferably 2 to 10 parts by mass, per 100 parts by mass of the above-mentioned rubber component. In addition, in the rubber composition of the present invention, the content of the silane coupling agent is preferably 1 to 20 mass %, and more preferably 5 to 15 mass %, relative to the above-mentioned silica content, because the effects of the present invention are more excellent.

[0062] (Carbon Black) The rubber composition of the present invention preferably further contains carbon black because the effects of the present invention are more excellent. The nitrogen adsorption specific surface area (N 2 SA) is not particularly limited, but is preferably 50 to 200 m because the effect of the present invention is superior. 2 / g, and 70 to 150m 2 It is more preferable that the molecular weight is / g. Here, the nitrogen adsorption specific surface area (N 2 SA) is the amount of nitrogen adsorption on the surface of carbon black measured according to JIS K6217-2:2001 "Part 2: Determination of specific surface area - Nitrogen adsorption method - Single point method." The carbon black is not particularly limited, and various grades such as SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, IISAF-HS, HAF-HS, HAF, HAF-LS, FEF, GPF, and SRF can be used. In the rubber composition of the present invention, the content of carbon black is not particularly limited, but in order to obtain better effects of the present invention, the content is preferably 1 to 100 parts by mass, and more preferably 2 to 50 parts by mass, per 100 parts by mass of the above-mentioned rubber component.

[0063] (Application) The rubber composition of the present invention can be suitably used for, for example, tires, conveyor belts, hoses, vibration-proof materials, rubber rolls, outer covers of railway cars, etc. In particular, it can be suitably used for tires (particularly treads).

[0064] [tire] The tire of the present invention is a tire manufactured using the above-mentioned rubber composition of the present invention. FIG. 1 shows a partial cross-sectional schematic view of a tire representing one example of an embodiment of a tire of the present invention, but the tire of the present invention is not limited to the embodiment shown in FIG.

[0065] In FIG. 1, the tire has a bead portion 1 , a sidewall portion 2 , and a tire tread portion 3 . Between the pair of left and right bead portions 1, a carcass layer 4 having fiber cords embedded therein is installed, and the ends of the carcass layer 4 are folded back and wrapped around the bead cores 5 and bead fillers 6 from the inside to the outside of the tire. In the tire tread portion 3, a belt layer 7 is disposed on the outer side of the carcass layer 4 over one circumference of the tire. In addition, a rim cushion 8 is disposed in the bead portion 1 at a portion that comes into contact with the rim.

[0066] There is no particular limitation on which component part of the tire of the present invention the rubber composition of the present invention is applied to, but one preferred embodiment is to apply the rubber composition of the present invention to the tire tread portion of the tire of the present invention.

[0067] The tire of the present invention can be manufactured, for example, according to a conventionally known method. The gas that can be filled into the tire of the present invention can be, for example, normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium. EXAMPLES

[0068] The present invention will be described in further detail below with reference to examples. The materials, amounts, ratios, processing contents, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following examples.

[0069] (Preparation of specific denaturant) Ammonium chloride (0.8 g) was added to N,N'-bis(3-trimethoxysilylpropyl)-1,3-propyldiamine (structure below, 28 g), and the mixture was heated at 100°C for 9 hours and stirred while removing methanol.

[0070] [ka] After the reaction, the resulting mixture was passed through a flash column to remove volatile components and purify to obtain a modifier. The denaturant obtained as above was 1 Analysis by H-NMR (nuclear magnetic resonance) confirmed that 1,1'-(1,3-propanediyl)bis[2,2-dimethoxy-1-aza-2-silacyclopentane] was produced. The structure of the resulting modifier is as follows: The modifier obtained as described above is hereinafter also referred to as modifier 1. Modifier 1 corresponds to the specific modifier in the present invention. The molecular weight of modifier 1 is 334. [ka]

[0071] [Production of modified diene polymer] <Comparative Example 1: Unmodified Liquid BR> 1,3-butadiene 1150ml (Takachiho Chemical) (net butadiene 13.6mol), n-butyllithium 100ml (Kanto Chemical, 1.55mol / L (hexane solution), hereinafter) (net n-butyllithium 0.155mol), 2,2-di(2-tetrahydrofuryl)propane (0.0005mol. TCI, hereinafter) were added to 5.4L of cyclohexane (Kanto Chemical, hereinafter) and stirred for 24 hours at room temperature. Then, 100ml of methanol was added to the reaction system to terminate the polymerization. The obtained polymer solution was added to a large amount of methanol, and the methanol insoluble components were separated and purified, and vacuum dried for 24 hours at 50℃. As a result, unmodified liquid polybutadiene (unmodified liquid BR, Mw=10,000g / mol) was obtained in a yield of 95%.

[0072] <Example 1: Modified Liquid BR1> 1,150 ml of 1,3-butadiene (net butadiene is 13.6 mol), 100 ml of n-butyllithium (net n-butyllithium is 0.155 mol), and 2,2-di(2-tetrahydrofuryl)propane (0.0005 mol) were added to 5.4 L of cyclohexane, and the mixture was stirred at room temperature for 24 hours. Next, 50 g (0.15 mol) of the above-mentioned modifier 1 was added to the reaction system to terminate the polymerization. The obtained polymer solution was added to a large amount of methanol, and the methanol-insoluble components were separated and purified, and then vacuum-dried at 50°C for 24 hours. As a result, liquid BR (modified liquid BR1) containing polybutadiene having functional groups derived from modifier 1 at its terminals was obtained in a yield of 95%. The Mw of modified liquid BR1 was 10,000 g / mol and Mw / Mn was 1.1. Modified liquid BR1 was liquid at 25°C.

[0073] Example 1 (denatured liquid BR1) 1 H-NMR chart (CDCl 3 , 20℃) is shown in Figure 2. In FIG. 2, the peak in region R1 is a proton (-Si-OCH) of a methoxy group bonded to Si in the functional group (functional group derived from 1,1'-(1,3-propanediyl)bis[2,2-dimethoxy-1-aza-2-silacyclopentane]) possessed by the modified liquid BR1. 3 ) The peak in region R2 is assigned to a proton bonded to a carbon atom adjacent to a silyl group in the functional group (functional group derived from 1,1′-(1,3-propanediyl)bis[2,2-dimethoxy-1-aza-2-silacyclopentane]) contained in the modified liquid BR1. The above 1 From the results of H-NMR, it is considered that a functional group derived from 1,1′-(1,3-propanediyl)bis[2,2-dimethoxy-1-aza-2-silacyclopentane] was introduced into the modified liquid BR1 obtained in Example 1. In detail, the modified liquid BR1 is considered to contain at least modified BR having a linear polybutadiene main chain and one functional group represented by the following formula (2-1) at one end, where * represents the bonding position with the main chain (linear polybutadiene). [ka]

[0074] <Example 2: Modified Liquid BR2> 1,150 ml of 1,3-butadiene (net butadiene is 13.6 mol), 100 ml of n-butyllithium (net n-butyllithium is 0.155 mol), and 2,2-di(2-tetrahydrofuryl)propane (0.0005 mol) were added to 5.4 L of cyclohexane, and the mixture was stirred at room temperature for 24 hours. Next, 25 g (0.075 mol) of the above-mentioned modifier 1 was added to the reaction system to terminate the polymerization. The obtained polymer solution was added to a large amount of methanol, and the methanol-insoluble components were separated and purified, and then vacuum-dried at 50°C for 24 hours. As a result, liquid BR (modified liquid BR2) containing polybutadiene having functional groups derived from modifier 1 at its terminals was obtained in a yield of 95%. The Mw of modified liquid BR2 was 10,000 g / mol and Mw / Mn was 1.5. Modified liquid BR2 was liquid at 25°C.

[0075] Denatured liquid BR2 1 H-NMR (CDCl 3 ,20℃) measurement, the denatured liquid BR2 1 The chemical shift δ of H-NMR is that of Example 1 (denatured liquid BR1). 1 The results were similar to those of the H-NMR chemical shift δ. The above 1 From the results of H-NMR, it is considered that functional groups derived from 1,1'-(1,3-propanediyl)bis[2,2-dimethoxy-1-aza-2-silacyclopentane] were introduced into the modified liquid BR2 obtained in Example 2. In detail, the modified liquid BR2 is considered to include at least a terminally modified BR having a linear polybutadiene main chain and one functional group represented by the above formula (2-1) at one end, and an internally modified BR (having a functional group inside the modified BR) in which two linear polybutadienes are bonded via a functional group represented by the following formula (3-1). In formula (2-1), * represents the bonding position with the main chain (linear polybutadiene). In formula (3-1), * represents the bonding position with the linear polybutadiene. [ka]

[0076] <Example 3: Modified Liquid BR3> 1,3-butadiene 1150ml (net butadiene 13.6mol), n-butyllithium 40ml (net n-butyllithium 0.062mol), 2,2-di(2-tetrahydrofuryl)propane (0.0005mol) were added to 5.4L of cyclohexane, and the mixture was stirred at room temperature for 24 hours. Next, 20g (0.06mol) of the above-mentioned modifier 1 was added to the reaction system to terminate the polymerization. The obtained polymer solution was added to a large amount of methanol, and the methanol-insoluble components were separated and purified, and then vacuum dried at 50℃ for 24 hours. As a result, liquid BR (modified liquid BR3) containing polybutadiene having functional groups derived from modifier 1 at its terminals was obtained in a yield of 95%. The Mw of modified liquid BR3 was 50,000 g / mol and Mw / Mn was 1.1. Modified liquid BR3 was liquid at 25°C.

[0077] Modified liquid BR3 1 H-NMR (CDCl 3 ,20℃) measurement, the denatured liquid BR3 1 The chemical shift δ of H-NMR is that of Example 1 (denatured liquid BR1). 1 The results were similar to those of the H-NMR chemical shift δ. The above 1From the results of H-NMR, it is considered that functional groups derived from 1,1′-(1,3-propanediyl)bis[2,2-dimethoxy-1-aza-2-silacyclopentane] were introduced into the modified liquid BR3 obtained in Example 3. In detail, the modified liquid BR3 is considered to contain at least modified BR having a linear polybutadiene main chain and one functional group represented by the above formula (2-1) at one end. In formula (2-1), * represents the bonding position with the main chain (linear polybutadiene).

[0078] <Example 4: Modified Liquid BR4> 1,150 ml of 1,3-butadiene (net butadiene is 13.6 mol), 40 ml of n-butyllithium (net n-butyllithium is 0.062 mol), and 2,2-di(2-tetrahydrofuryl)propane (0.0005 mol) were added to 5.4 L of cyclohexane, and the mixture was stirred at room temperature for 24 hours. Next, 10 g (0.03 mol) of the above-mentioned modifier 1 was added to the reaction system to terminate the polymerization. The obtained polymer solution was added to a large amount of methanol, and the methanol-insoluble components were separated and purified, and then vacuum-dried at 50°C for 24 hours. As a result, liquid BR (modified liquid BR4) containing polybutadiene having functional groups derived from modifier 1 at its terminals was obtained in a yield of 95%. The Mw of modified liquid BR4 was 50,000 g / mol and Mw / Mn was 1.5. Modified liquid BR4 was liquid at 25°C.

[0079] Modified liquid BR4 1 H-NMR (CDCl 3 ,20℃) measurement, the denatured liquid BR3 1 The chemical shift δ of H-NMR is that of Example 1 (denatured liquid BR1). 1 The results were similar to those of the H-NMR chemical shift δ. The above 1 From the results of H-NMR, it is considered that functional groups derived from 1,1'-(1,3-propanediyl)bis[2,2-dimethoxy-1-aza-2-silacyclopentane] were introduced into the modified liquid BR4 obtained in Example 4. In detail, the modified liquid BR4 is considered to include at least a terminally modified BR having a linear polybutadiene main chain and one functional group represented by the above formula (2-1) at one end, and an internally modified BR (having a functional group inside the modified BR) having two linear polybutadienes bonded via a functional group represented by the above formula (3-1). In formula (2-1), * represents the bonding position with the main chain. In formula (3-1), * represents the bonding position with the linear polybutadiene.

[0080] The modification, Mw, Mn, and Mw / Mn (molecular weight distribution) of the modified diene polymers of the examples and the unmodified liquid BR of the comparative examples are summarized in Table 1. The units of Mw and Mn are g / mol. [Table 1]

[0081] [Production of rubber composition] The components shown in Table 3 (rubber composition) below were used in the proportions (parts by mass) shown in the table, and the components shown in Table 2 (common formulation) below were used in the proportions (parts by mass) shown in the table. The proportions of the components shown in Table 2 (common formulation) are based on 100 parts by mass of the rubber component (rubber component containing SBR and BR) shown in Table 3 (rubber composition). Specifically, first, the components shown in Table 3 below and the components shown in Table 2 except for sulfur and vulcanization accelerator were mixed in a Banbury mixer at 80°C for 5 minutes to obtain a mixture. Next, sulfur and vulcanization accelerator were mixed into the mixture using a roll to obtain a rubber composition.

[0082] Details of each component shown in Table 3 are as follows. (Rubber component) SBR: Styrene butadiene rubber. TUFDENE E581 (SBR, glass transition temperature: -36°C, styrene content: 35.6% by mass, vinyl bond content: 41.3%, oil-extended product (oil extension amount: 37.5% by mass), manufactured by Asahi Kasei Chemicals Corporation). The amount shown in the "SBR" column in Table 2 is the amount of net SBR. The weight average molecular weight is 1,100,000 g / mol BR: Polybutadiene rubber. NIPOL1502 (BR, manufactured by Zeon Corporation) weight average molecular weight is 400,000 g / mol

[0083] (silica) ·Silica: ZEOSIL 1165MP (CTAB adsorption specific surface area: 159m 2 / g, manufactured by Rhodia)

[0084] Unmodified liquid BR: Unmodified liquid BR of Comparative Example 1

[0085] (Modified diene polymer) Modified liquid BR1 to 4: Modified liquid BR1 to 4 of Examples 1 to 4

[0086] Details of each component shown in Table 2 (common composition) are as follows. Carbon black: Show Black N339 (Cabot Japan) Stearic acid: Stearic acid YR (NOF Corporation) Processing aid: Actiplast ST (Rhein Chemie) Anti-aging agent: SANTOFLEX 6PPD (Soltia Europe) Wax: Sunnock (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) Silane coupling agent: Si69 (manufactured by Evonik Degussa) Oil: Extract No. 4 S (Showa Shell Sekiyu Co., Ltd.) Zinc oxide: Zinc oxide No. 3 (Seido Chemical Co., Ltd.) Sulfur: Oil-treated sulfur (Karuizawa Refinery Co., Ltd.) The amount shown in the "Sulfur" column in Table 3 is the net amount of sulfur. Vulcanization accelerator CZ: Noccela CZ-G (manufactured by Ouchiko Chemical Industry Co., Ltd.) Vulcanization accelerator DPG: Soxinol DG: (Sumitomo Chemical Co., Ltd.)

[0087] [Table 2]

[0088] 〔evaluation〕 The rubber compositions thus obtained were evaluated as follows, and the results are shown in Table 3.

[0089] <Low fuel consumption (low rolling resistance)> Each of the resulting rubber compositions (unvulcanized) was press-vulcanized in a mold (15 cm×15 cm×0.2 cm) at 160° C. for 15 minutes to prepare a vulcanized rubber sheet (cured product). The loss tangent tan δ(60° C.) of the produced vulcanized rubber sheet was measured at a temperature of 60° C. under conditions of an initial strain of 10%, an amplitude of ±2%, and a frequency of 20 Hz using a viscoelasticity spectrometer (manufactured by Toyo Seiki Seisakusho, Ltd.).

[0090] The results of tan δ@60°C for the examples and comparative examples are shown as an index in Table 3. The results are expressed as an index with the reciprocal of tan δ@60°C for Comparative Example 1-1 set to 100. In the present invention, the rubber was evaluated as having excellent fuel economy (low rolling resistance of tires) when cured, when the index exceeded 100. The larger the index was above 100, the smaller the tan δ@60°C was, and the more excellent the fuel economy was. On the other hand, when the index was 100 or less, the fuel economy of the cured product was evaluated as poor.

[0091] [Silica adsorption rate of modified diene polymer] In 15 g of xylene, 1.5 g of each modified diene polymer obtained in the examples (or the unmodified liquid BR obtained in Comparative Example 1) and 3.0 g of silica were dissolved, and heated and stirred at 140° C. for 20 minutes. Then, the mixture was filtered, recovered, vacuum dried at 80° C. for 24 hours, and the mass (final mass) was measured. The silica adsorption rate of the modified diene polymer, etc. was calculated by the following formula. (Silica adsorption rate)=(final mass-mass of silica used in evaluation) / (mass of modified diene polymer used in evaluation)×100 (unit: %) The results are shown in the following Table 3. A higher silica adsorption rate means that the modified diene polymer has better silica adsorption ability. In practice, a rate of 10% or more is preferable.

[0092] [Table 3]

[0093] From the results in Table 3, it was confirmed that the rubber composition of the present invention exhibits the desired effects. It was also confirmed that the polymer of the present invention can provide a rubber composition that exhibits excellent fuel economy when cured. It was also confirmed that the fuel economy of the rubber composition of the present invention improves substantially in conjunction with the silica adsorption rate of the modified diene polymer of the present invention.

[0094] On the other hand, Comparative Example 1-1, which did not contain the polymer of the present invention but contained unmodified liquid BR instead, had poor fuel economy when cured. This is believed to be because the unmodified liquid BR was unmodified and had a silica adsorption rate of 0%. [Explanation of symbols]

[0095] 1 Bead section 2 Sidewall 3 Tire tread 4 Carcass layer

Claims

1. A modified diene polymer having a functional group derived from a modifying agent represented by the following formula (1) and having a weight average molecular weight of 500 to 80,000 g / mol: 【Chemistry 1】 In formula (1), R １ ~R ２ one of which is an alkoxy group and the other is an alkoxy group or an alkyl group; R ３ ~R ４ one of which is an alkoxy group and the other is an alkoxy group or an alkyl group; R ５ is an alkylene group.

2. 2. The modified diene polymer according to claim 1, wherein the main chain is polybutadiene, polyisoprene, or a styrene-butadiene copolymer.

3. The modified diene polymer according to claim 1, having a molecular weight distribution of 1.0 to 2.

0.

4. A rubber composition comprising a rubber component having a weight average molecular weight of 100,000 g / mol or more, silica, and the modified diene polymer according to any one of claims 1 to 3.

5. The rubber composition according to claim 4, wherein the content of the modified diene polymer is 20 parts by mass or less based on 100 parts by mass of the rubber component.

6. A tire manufactured using the rubber composition according to claim 4.

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