Method for manufacturing a rubber composition, rubber composition, and tire

Abstract

To provide a method for producing a rubber composition capable of obtaining a rubber composition which can improve the dispersibility of a filler and has excellent low-loss properties.SOLUTION: There is provided a method for producing a rubber composition comprising a rubber component (A) containing at least one selected from natural rubber and a synthetic diene rubber, a filler containing an inorganic filler (B), a silane coupling agent (C) and a vulcanization accelerator (D), wherein the rubber composition is kneaded in multiple stages, the rubber component (A), a part or the whole of the inorganic filler (B), a part or the whole of the silane coupling agent (C) and the vulcanization accelerator (D) are kneaded in a first stage of the kneading and the rubber component contains a modified copolymer modified by a modifying agent containing a compound represented by formula (1).SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for producing a rubber composition, a rubber composition, and a tire. [Background technology]

[0002] In recent years, driven by growing environmental concerns and the global trend towards regulating carbon dioxide emissions, there has been an increasing demand for more fuel-efficient automobiles. To meet these demands, tire performance is also required to reduce rolling resistance. While optimizing tire structure has been considered as a method to reduce tire rolling resistance, using rubber compositions with lower heat generation (lower loss) is now a common practice.

[0003] One known method for obtaining a rubber composition with such low loss properties is to use an inorganic filler such as silica as a filler. However, when inorganic fillers such as silica are incorporated into rubber compositions containing inorganic fillers, the inorganic fillers, especially silica, tend to aggregate within the rubber composition (due to hydroxyl groups on the silica surface). Therefore, various technologies have been developed to improve the dispersibility of the fillers within the rubber composition.

[0004] For example, Patent Document 1 discloses a technique for improving the elastic modulus and tanδ by enhancing the chemical interaction between the rubber component and the filler, and improving the dispersibility of the reinforcing filler in the rubber composition, by including a rubber component having a diene rubber, a reinforcing filler, and a compound having a specific amidine structure. Furthermore, Patent Document 2 discloses a technique for improving the dispersibility of a filler and reducing losses by using a conjugated diene polymer modified with a modifier containing an oligosiloxane and a specific compound having a tertiary amino group, together with the filler.

[0005] However, considering the need to optimize rubber performance to a higher level in the future, the technologies disclosed in Patent Documents 1 and 2 may not provide sufficient low loss, and further technological improvements were desired. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Special Publication No. 2014-501827 [Patent Document 2] Japanese Patent Publication No. 2021-085029 [Overview of the project] [Problems that the invention aims to solve]

[0007] Therefore, an object of the present invention is to provide a method for producing a rubber composition that can be obtained by improving the dispersibility of the filler and obtaining a rubber composition with excellent low loss properties. Another object of the present invention is to provide a rubber composition with excellent low loss properties and a tire with reduced rolling resistance. [Means for solving the problem]

[0008] The inventors of this invention conducted intensive research to solve the above problems. They found that by using a conjugated diene polymer modified with a modifier containing an oligosiloxane and a specific compound having a tertiary amino group as the rubber component, and by properly performing the process of adding a specific type of vulcanization accelerator during the first stage of the kneading process, the dispersibility of the filler can be greatly improved, thereby reducing losses.

[0009] The present invention provides a method for producing a rubber composition comprising: a rubber component (A) containing at least one selected from natural rubber and synthetic diene rubber; a filler containing an inorganic filler (B); a silane coupling agent (C); and a vulcanization accelerator (D), The rubber composition is kneaded in multiple stages, In the first stage of the mixing process, the rubber component (A), part or all of the inorganic filler (B), part or all of the silane coupling agent (C), and the vulcanization accelerator (D) are mixed together. The rubber component is characterized by containing a modified copolymer that has been modified with a modifying agent containing a compound represented by formula (1). By incorporating the above configuration, the dispersibility of the filler can be improved, and a rubber composition with excellent low loss properties can be obtained.

[0010] Furthermore, in the method for producing the rubber composition of the present invention, the copolymer modified by the modifying agent containing the compound represented by formula (1) is a copolymer having conjugated diene units and aromatic vinyl units, and it is preferable that the content of aromatic vinyl units in the copolymer is 40% by mass or less. In this case, the low loss properties of the rubber composition can be further improved.

[0011] Furthermore, in the method for producing the rubber composition of the present invention, the vulcanization accelerator (D) is preferably at least one vulcanization accelerator selected from guanidines, sulfenamides, thiazoles, thirams, dithiocarbamates, thioureas, and xanthogenicates, and more preferably at least one guanidine vulcanization accelerator or at least one thiourea vulcanization accelerator. In this case, the coupling function of the silane coupling agent can be enhanced, and the low loss properties of the rubber composition can be further improved.

[0012] Furthermore, in the method for producing the rubber composition of the present invention, it is preferable that in the first step of kneading, after kneading all or part of the rubber component (A), the inorganic filler (B), and all or part of the silane coupling agent (C), the accelerator (D) is added and kneaded further. In this case, the coupling function of the silane coupling agent can be enhanced, and the low loss properties of the rubber composition can be further improved.

[0013] Furthermore, in the method for producing the rubber composition of the present invention, it is preferable that the maximum temperature of the rubber composition in the first stage of kneading is 120 to 190°C. In this case, the coupling function of the silane coupling agent can be enhanced, and the low loss property of the rubber composition can be further improved.

[0014] Also, in the method for producing the rubber composition of the present invention, it is preferable that the silane coupling agent (C) is at least one compound selected from the group consisting of compounds represented by the following general formulas (I) to (IV).

Chemical formula

Chemical formula

[0015] Furthermore, in the method for producing the rubber composition of the present invention, it is preferable that the inorganic filler (B) is silica. In this case, the low loss properties of the rubber composition can be further improved.

[0016] Furthermore, in the method for producing the rubber composition of the present invention, it is preferable that the filler further contains carbon black. In this case, the abrasion resistance of the rubber composition can be improved.

[0017] Furthermore, in the method for producing the rubber composition of the present invention, it is preferable that the modifying agent is one of the formulas (1a) to (1e). In this case, the low loss properties of the rubber composition can be further improved. [ka] JPEG0007897044000006.jpg45158

[0018] Furthermore, in the method for producing the rubber composition of the present invention, it is preferable that the modified copolymer is a modified copolymer further modified with a modifying agent containing a compound represented by formula (2). In this case, the low loss properties of the rubber composition can be further improved. [ka] (In formula (2), R1 to R3 are independently of each other: hydrogen; C1 to C30 alkyl group; C2 to C30 alkenyl group; C2 to C30 alkynyl group; C1 to C30 heteroalkyl group, C2 to C30 heteroalkenyl group; C2 to C30 heteroalkynyl group; C5 to C30 cycloalkyl group; C6 to C30 aryl group; or C3 to C30 heterocyclic group, and R4 is a single bond; C1 to C20 alkylene group with a substituent substituted or unsubstituted; C5 to C20 cycloalkylene group with a substituent substituted or unsubstituted; or C5 to C20 arylene group with a substituent substituted or unsubstituted, where the substituent is a C1 to C10 alkyl group, C5 to C10 R5 is a cycloalkyl group or an aryl group having 6 to 20 carbon atoms, where R5 is an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; a heterocyclic group having 3 to 30 carbon atoms; or an active group represented by the following chemical formula (2a) or chemical formula (2b), where n is an integer from 1 to 5, and at least one of R5 is an active group represented by the following chemical formula (2a) or chemical formula (2b), and when n is an integer from 2 to 5, multiple R5s may be the same as or different from each other. [ka] In formula (2a), R6 is a C1-C20 alkylene group with a substituent, substituted or unsubstituted; a C5-C20 cycloalkylene group with a substituent, substituted or unsubstituted; or a C6-C20 arylene group with a substituent, where the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group, and R7 and R8 are independently a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 The aryl group is a C1-C20 alkylene group, and R9 is a hydrogen; a C1-C30 alkyl group; a C2-C30 alkenyl group; a C2-C30 alkynyl group; a C1-C30 heteroalkyl group; a C2-C30 heteroalkenyl group; a C2-C30 heteroalkynyl group; a C5-C30 cycloalkyl group; a C6-C30 aryl group; or a C3-C30 heterocyclic group. X is an N, O, or S atom, and if X is O or S, R9 is absent. [ka] In equation (2b), R 10 R is a C1-C20 alkylene group with a substituent that is substituted or unsubstituted; a C5-C20 cycloalkylene group with a substituent that is substituted or unsubstituted; or a C6-C20 arylene group with a substituent that is substituted or unsubstituted, where the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group, 11 and R 12 These are, independently of each other, alkyl groups having 1 to 30 carbon atoms; alkenyl groups having 2 to 30 carbon atoms; alkynyl groups having 2 to 30 carbon atoms; heteroalkyl groups having 1 to 30 carbon atoms; heteroalkenyl groups having 2 to 30 carbon atoms; heteroalkynyl groups having 2 to 30 carbon atoms; cycloalkyl groups having 5 to 30 carbon atoms; aryl groups having 6 to 30 carbon atoms; and heterocyclic groups having 3 to 30 carbon atoms.

[0019] The rubber composition of the present invention is characterized by being obtained by the method for producing the rubber composition of the present invention described above. By incorporating the above configuration, excellent low loss performance can be achieved.

[0020] The tire of the present invention is characterized by using the rubber composition of the present invention described above. By incorporating the above configuration, a significant reduction in rolling resistance can be achieved. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a method for producing a rubber composition that improves the dispersibility of the filler and yields a rubber composition with excellent low loss properties. Furthermore, according to the present invention, it is possible to provide a rubber composition with excellent low loss properties and a tire with reduced rolling resistance. [Modes for carrying out the invention]

[0022] The following describes, in detail, an embodiment of the method for producing the rubber composition of the present invention, the rubber composition, and a tire. <Method for manufacturing rubber composition> The present invention provides a method for producing a rubber composition comprising: a rubber component (A) containing at least one selected from natural rubber and synthetic diene rubber; a filler containing an inorganic filler (B); a silane coupling agent (C); and a vulcanization accelerator (D). Furthermore, the method for producing the rubber composition of the present invention involves kneading the rubber composition in multiple stages, In the first stage of the mixing process, the rubber component (A), part or all of the inorganic filler (B), part or all of the silane coupling agent (C), and the vulcanization accelerator (D) are mixed together. The rubber component is characterized by containing a modified copolymer that has been modified with a modifying agent containing a compound represented by formula (1). [ka] (In the formula, R1 to R8 are each independently alkyl groups having 1 to 20 carbon atoms; L1 and L2 are each independently alkylene groups having 1 to 20 carbon atoms; and n is an integer from 2 to 4.)

[0023] By using a conjugated diene polymer modified with a modifying agent containing an oligosiloxane and a compound represented by formula (1) that includes a tertiary amino group, which are filler affinity groups, as the rubber component (A), the dispersibility of fillers (C) such as silica can be improved. In addition, by adjusting the kneaded product prepared in the first step of kneading, the coupling activity of the silane coupling agent (C) can be enhanced, and the dispersibility of the filler (C) in the rubber composition can be improved. As a result of these synergistic effects, the low heat generation of the obtained rubber composition can be greatly improved.

[0024] In the aforementioned kneading process, there are no particular restrictions on the kneading equipment used for kneading, and it can be appropriately selected according to the purpose. Examples include single-screw compounding extruders; multi-screw compounding extruders (continuous compounding devices); compounders with meshing or non-meshing rotary rotors such as Banbar mixers, intermixers, and kneaders; and rolls (batch compounding devices). Furthermore, various conditions in the kneading process, such as the rotor rotation speed, ram pressure, kneading temperature, and type of kneading equipment, can be selected as appropriate.

[0025] In the method for producing the rubber composition of the present invention, the rubber composition is kneaded in multiple stages as described above. Then, in the first stage of the mixing process, the rubber component (A), part or all of the inorganic filler (B), part or all of the silane coupling agent (C), and the vulcanization accelerator (D) are mixed together. The reason for adding the vulcanization accelerator (D) in the first stage of mixing is to enhance the coupling activity of the silane coupling agent (C).

[0026] Furthermore, in the method for producing the rubber composition of the present invention, it is preferable to add the vulcanization accelerator (D) after kneading all or part of the rubber component (A), the inorganic filler (B), and all or part of the silane coupling agent (C) in the first kneading step, and then knead further, in order to further suppress the reduction of the effect of improving the coupling function activity due to the inclusion of the vulcanization accelerator (D). In other words, the reaction between the silane coupling agent (C) and the rubber component (A) can proceed after the reaction between the inorganic filler (B) and the silane coupling agent (C) has proceeded sufficiently.

[0027] Furthermore, it is more preferable that the time between adding the rubber component (A), all or part of the inorganic filler (B), and all or part of the silane coupling agent (C) in the first stage of mixing, and adding the vulcanization accelerator (D) midway through the first stage, be 10 to 180 seconds. The lower limit of this time is more preferably 30 seconds or more, the upper limit is more preferably 150 seconds or less, and even more preferably 120 seconds or less. If this time is 10 seconds or more, the reaction between (B) and (C) can proceed sufficiently. If this time exceeds 180 seconds, the reaction between (B) and (C) has already proceeded sufficiently, so it is difficult to enjoy any further effects, and it is preferable to set the upper limit to 180 seconds.

[0028] In the present invention, it is preferable that the molar amount X of organic acid in the rubber composition in the first stage of kneading is related to the molar amount Y of the vulcanization accelerator (D) by the following formula [3]. This is to suitably suppress the reduction of the coupling function enhancement effect due to the presence of a large amount of organic acid caused by the addition of the accelerator (D). 0 ≤ X ≤ 1.5 × Y ···[3] In order to reduce the amount of organic acid in the first stage (X) of kneading, it is preferable that the organic acid be added from the second stage of kneading onward.

[0029] In the manufacturing method of the present invention, it is preferable that the maximum temperature of the rubber composition in the first kneading stage is 120 to 190°C. This is to allow the reaction between the inorganic filler (B) and the silane coupling agent (C) to proceed sufficiently. From this viewpoint, it is more preferable that the maximum temperature of the rubber composition in the first kneading stage is 130 to 190°C, and even more preferable that it is 140 to 180°C.

[0030] In the manufacturing method of the present invention, the kneading step includes at least two stages: a first stage of kneading that does not include other vulcanizing agents, etc., except for the vulcanizing accelerator (D), and a final stage of kneading that includes the vulcanizing agent, etc., and may include an intermediate stage of kneading that does not include other vulcanizing agents, etc., except for the accelerator (D), as necessary. Here, "vulcanizing agent, etc." refers to a vulcanizing agent and a vulcanizing accelerator. The first stage of mixing refers to the initial stage in which both the rubber component (A), the inorganic filler (B), and the silane coupling agent (C) are mixed. This stage does not include the stage in which fillers other than the rubber component (A) and the inorganic filler (B) are mixed, or the stage in which only the rubber component (A) is pre-mixed.

[0031] As described above, the method for producing the rubber composition of the present invention is a method for producing a rubber composition comprising a rubber component (A) containing at least one selected from natural rubber and synthetic diene rubber, a filler containing an inorganic filler (B), a silane coupling agent (C), and a vulcanization accelerator (D). The following describes each component that makes up the rubber composition.

[0032] (Rubber component) The rubber composition produced by the manufacturing method of the present invention contains a rubber component (A) which includes at least one selected from natural rubber and synthetic diene rubber. The abrasion resistance of the rubber composition can be improved by including at least one rubber component selected from natural rubber and synthetic diene rubber. Furthermore, the dispersibility of the inorganic filler (B) can be improved by modifying it with a modifier containing a compound represented by formula (1), which will be described later.

[0033] The type of synthetic diene rubber contained in the rubber component (A) is not particularly limited and can be appropriately selected according to the required performance. Examples include butadiene rubber (BR) (wherein BR refers to polybutadiene, which is a polymer of 1,3-butadiene, and does not include copolymers of butadiene with other polymers), isoprene rubber (IR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), and the like.

[0034] Furthermore, the natural rubber and synthetic diene rubber may be composed solely of unmodified rubber or of modified rubber. However, in this invention, the synthetic diene rubber contained in the rubber component (A) does not include modified copolymers modified with a modifying agent containing the compound represented by formula (1) described later. Therefore, natural rubber and synthetic diene rubber modified with a modifying agent containing the compound represented by formula (1) described later are included in the modified copolymers described later.

[0035] Furthermore, the rubber component (A) may also contain rubber other than diene-based rubber (non-diene-based rubber), as long as it does not impair the objectives of the present invention. Examples of the aforementioned non-diene rubbers include ethylene propylene diene rubber (EPDM), ethylene propylene rubber (EPM), and butyl rubber (IIR).

[0036] Furthermore, in the rubber composition of the present invention, the rubber component must contain a modified copolymer (hereinafter sometimes simply referred to as a "modified conjugated diene polymer") modified with a modifying agent containing a compound represented by formula (1). [ka] By using a conjugated diene polymer modified with a modifier containing an oligosiloxane and a tertiary amino group, which are filler affinity groups, as the rubber component (A), the dispersibility of inorganic fillers (B) such as silica can be improved. As a result, the rubber composition of the present invention exhibits significantly improved low heat generation and improved dispersibility of the filler, without compromising other physical properties such as reinforcing properties, handling stability when applied to tires, and processability.

[0037] In formula (1) above, R1 to R8 are each independently alkyl groups having 1 to 20 carbon atoms; L1 and L2 are each independently alkylene groups having 1 to 20 carbon atoms; and n is an integer from 2 to 4.

[0038] Specifically, in formula (1), R1 to R4 may each be independently substituted or unsubstituted C1 to C20 alkyl groups, and if R1 to R4 are substituted, they may each be independently C1 to C10 alkyl groups, C3 to C10 cycloalkyl groups, C1 to C10 alkoxy groups, C4 to C10 cycloalkoxy groups, C6 to C12 aryl groups, C6 to C12 aryloxy groups, or C2 to C12 alkanoyloxy groups (alkanoyl, RaCOO - In this case, Ra may be substituted with one or more substituents selected from the group consisting of an alkyl group having 1 to 9 carbon atoms, an aralkyloxy group having 7 to 13 carbon atoms, an arylalkyl group having 7 to 13 carbon atoms, and an alkylaryl group having 7 to 13 carbon atoms. More specifically, R1 to R4 may be substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms, and even more specifically, R1 to R4 may each be independently substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms.

[0039] Furthermore, in formula (1), R5 to R8 are each independently substituted or unsubstituted C1 to C20 alkyl groups, specifically substituted or unsubstituted C1 to C10 alkyl groups, and more specifically substituted or unsubstituted C1 to C6 alkyl groups. If substituted, they may be substituted with substituents as described above for R1 to R4. If R5 to R8 are not alkyl groups but hydrolyzable substituents, the N-R5R6 and N-R7R8 bonds may be hydrolyzed to NH in the presence of moisture, which may adversely affect the processability of the polymer.

[0040] More specifically, in the compound represented by formula (1), R1 to R4 are methyl groups or ethyl groups, and R5 to R8 can be alkyl groups having 1 to 10 carbon atoms.

[0041] In the present invention, it is preferable that the amino groups in the compound represented by formula (1), namely N-R5R6 and N-R7R8, are tertiary amino groups. The tertiary amino groups provide even better processability when the compound represented by formula (1) is used as a modifying agent. Furthermore, if a protecting group to protect the amino group is bonded to R5-R8, or if hydrogen is bonded, it may be difficult to realize the effect of the compound represented by formula (1). When hydrogen is bonded, the anion reacts with hydrogen during the modification process and loses its reactivity, making the modification reaction itself impossible. When a protecting group is bonded, the modification reaction takes place, but it is deprotected by hydrolysis during post-processing while bonded to the polymer ends, becoming a primary or secondary amino group. This deprotected primary or secondary amino group may cause increased viscosity of the compound during subsequent compounding, potentially leading to reduced processability.

[0042] Furthermore, L1 and L2 in the compound represented by formula (1) are each independently substituted or unsubstituted alkylene groups having 1 to 20 carbon atoms. More specifically, L1 and L2 can each be an alkylene group having 1 to 10 carbon atoms, and more specifically, an alkylene group having 1 to 6 carbon atoms, such as a methylene group, an ethylene group, or a propylene group.

[0043] For L1 and L2 in the compound represented by formula (1) above, the closer the distance between the Si atom and N atom in the molecule, the better the effect. However, when Si is directly bonded to N, there is a risk that the bond between Si and N may break during a later processing step, and the secondary amino group generated at this time is likely to be washed away by water during post-processing. In the modified conjugated diene polymer produced, the amino group component that promotes bonding with the inorganic filler (B) such as silica makes it difficult to bond with the silica filler, and as a result, the dispersion effect of the dispersant may decrease. Considering the improvement effect depending on the length of the bond between Si and N, it is even more preferable that L1 and L2 are alkylene groups having 1 to 3 carbon atoms, such as a methylene group, an ethylene group, or a propylene group, and more specifically, they can be propylene groups. In addition, L1 and L2 can be substituted with substituents as described above for R1 to R4.

[0044] Furthermore, the compound represented by formula (1) is preferably one of the compounds represented by the following formulas (1a) to (1e), because it is possible to achieve even better low exothermic properties. [ka] JPEG0007897044000013.jpg46160

[0045] In the modifying agent of the present invention, the compound represented by formula (1) has an alkoxysilane structure that is bonded to the activating end of a conjugated diene polymer, while the Si-O-Si structure and the three or more amino groups bonded to the end exhibit affinity to fillers such as silica. This allows for better bonding between the filler and the modified conjugated diene polymer compared to conventional modifying agents containing only one amino group within the molecule. Furthermore, the degree of bonding at the active ends of the conjugated diene polymer is uniform, and when observing the change in molecular weight distribution before and after coupling, the molecular weight distribution remains constant even after coupling, without becoming significantly larger than before. Therefore, the physical properties of the modified conjugated diene polymer itself do not deteriorate, aggregation of fillers within the rubber composition is prevented, and the dispersibility of the fillers is improved, thereby improving the processability of the rubber composition. These effects, in particular, make it possible to improve the fuel efficiency, wear characteristics, and braking characteristics in a well-balanced manner when the rubber composition is applied to a tire.

[0046] The compound represented by formula (1) can be produced through the condensation reaction represented by the following reaction formula 1. [ka]

[0047] In reaction equation 1, R1 to R8, L1 and L2, and n are the same as those defined in equation (1) above, and R' and R'' are arbitrary substituents that do not affect the condensation reaction. For example, R' and R'' can each be independently identical to any one of R1 to R4.

[0048] The reaction of reaction equation 1 is carried out under acidic conditions, and any acid commonly used in condensation reactions can be used without restriction. Those skilled in the art can select the optimal acid according to various process variables such as the type of reactor in which the reaction is carried out, the starting materials, and the reaction temperature.

[0049] The copolymer modified by the modifying agent containing the compound represented by formula (1) can be any copolymer, but it is preferable that it is a copolymer having conjugated diene units and aromatic vinyl units. Furthermore, the conjugated diene units and aromatic vinyl units can be arranged and bonded in a disordered manner to form a random copolymer.

[0050] In the rubber composition of the present invention, it is preferable that the content of aromatic vinyl units in the copolymer (the mass of aromatic vinyl units relative to the total mass of the copolymer) is 40% by mass or less. This is because the low heat generation properties of the rubber composition can be further improved. From a similar viewpoint, it is preferable that the content of aromatic vinyl units is 30% by mass or less, and more preferably 20% by mass or less. Furthermore, from the viewpoint of maintaining good levels of handling stability and wear resistance when the rubber composition is applied to a tire, it is preferable that the content of aromatic vinyl units in the copolymer is 3% by mass or more.

[0051] Here, there are no particular restrictions on the type of conjugated diene monomer that forms the conjugated diene unit. For example, one or more selected from the group consisting of 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, isoprene, and 2-phenyl-1,3-butadiene can be used.

[0052] Furthermore, there are no particular limitations on the type of aromatic vinyl monomer that forms the aromatic vinyl unit. For example, one or more selected from the group consisting of styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 4-cyclohexylstyrene, 4-(p-methylphenyl)styrene, and 1-vinyl-5-hexylnaphthalene can be used.

[0053] Furthermore, the copolymer of the modified copolymer can be a combination of the conjugated diene monomer and aromatic vinyl monomer described above, but among these, styrene-butadiene rubber is preferred. This is because it can more reliably achieve superior low heat generation without degrading other properties, and it also provides excellent wet performance when applied to tires.

[0054] Furthermore, the modified copolymer may have a narrow molecular weight distribution of 1.1 to 3.0: Mw / Mn (also known as the polydispersity index (PDI)). If the molecular weight distribution of the modified copolymer exceeds 3.0 or is less than 1.1, the tensile properties and viscoelasticity may decrease when applied to a rubber composition. Considering the remarkable effect of controlling the molecular weight distribution of the modified copolymer on improving the tensile properties and viscoelasticity of the polymer, it is preferable to set the molecular weight distribution of the modified copolymer to 1.3 to 2.0. Note that by using the modifying agent, the modified copolymer will have a molecular weight distribution similar to that of the copolymer before modification.

[0055] The molecular weight distribution of the modified copolymer can be calculated from the ratio of the weight-average molecular weight (Mw) to the log-average molecular weight (Mn) (Mw / Mn). In this case, the number-average molecular weight (Mn) is the common average of the individual polymer molecular weights, calculated by measuring the molecular weights of n polymer molecules, summing these molecular weights, and dividing by n, while the weight-average molecular weight (Mw) represents the molecular weight distribution of the polymer composition. The average of the overall molecular weight can be expressed in grams per mole (g / mol). Furthermore, in the present invention, the weight-average molecular weight and the number-average molecular weight are polystyrene-equivalent molecular weights analyzed by gel permeation chromatography (GPC).

[0056] Furthermore, the modified copolymer satisfies the above-mentioned molecular weight distribution conditions and has a number-average molecular weight (Mn) of 50,000 g / mol to 2,000,000 g / mol, more specifically, 200,000 g / mol to 800,000 g / mol. The modified copolymer has a weight-average molecular weight (Mw) of 100,000 g / mol to 4,000,000 g / mol, more specifically, 300,000 g / mol to 1,500,000 g / mol.

[0057] If the weight-average molecular weight (Mw) of the modified copolymer is less than 100,000 g / mol, or the number-average molecular weight (Mn) is less than 50,000 g / mol, there is a risk of reduced tensile properties when applied to a rubber composition. Furthermore, if the weight-average molecular weight (Mw) exceeds 4,000,000 g / mol, or the number-average molecular weight (Mn) exceeds 2,000,000 g / mol, the processability of the modified copolymer will decrease, worsening the workability of the rubber composition, making mixing difficult, and making it difficult to sufficiently improve the physical properties of the rubber composition. More specifically, when the modified copolymer according to one embodiment of the present invention satisfies the conditions of weight-average molecular weight (Mw) and number-average molecular weight (Mn) simultaneously with the molecular weight distribution, it can improve the viscoelasticity and processability of a rubber composition in a well-balanced manner when applied to a rubber composition.

[0058] Furthermore, the present invention provides a method for producing the modified copolymer using a modifying agent containing the compound represented by formula (1). The method for producing the modified copolymer may specifically include: 1) a step of polymerizing an aromatic vinyl monomer and a conjugated diene monomer in a hydrocarbon solvent in the presence of an organoalkali metal compound to produce an active polymer in which an alkali metal is bonded to at least one end; and 2) a step of reacting the active polymer with a modifying agent containing the compound represented by chemical formula 1.

[0059] The step in 1) above is a step for producing an active polymer in which an alkali metal is bonded to at least one end, and can be carried out by polymerizing an aromatic vinyl monomer and a conjugated diene monomer in a hydrocarbon solvent in the presence of an organoalkali metal compound.

[0060] The hydrocarbon solvent is not particularly limited, but for example, one or more selected from the group consisting of n-pentane, n-hexane, n-heptane, isooctane, cyclohexane, toluene, benzene, and xylene can be used.

[0061] The aforementioned organoalkali metal compound can be used in an amount of 0.1 mmol to 1.0 mmol based on 100 g of the monomer. The organoalkali metal compound is not particularly limited, but for example, one or more selected from the group consisting of methyllithium, ethyllithium, propyllithium, n-butyllithium, s-butyllithium, t-butyllithium, hexyllithium, n-decyllithium, t-octyllithium, phenyllithium, 1-naphthyllithium, n-eicosyllithium, 4-butylphenyllithium, 4-tolylllithium, cyclohexyllithium, 3,5-di-n-heptylcyclohexyllithium, 4-cyclopentyllithium, sodium naphthyl, potassium naphthyl, lithium alkoxide, sodium alkoxide, potassium alkoxide, lithium sulfonate, sodium sulfonate, potassium sulfonate, lithium amide, sodium amide, potassium amide, and lithium isopropylamide can be used.

[0062] The polymerization in step 1) above may be carried out by further adding a polar additive as needed, and the polar additive can be added in an amount of 0.001 to 1.0 part by weight per 100 parts by weight of the total monomer. Specifically, it can be added in an amount of 0.005 to 0.5 parts by weight, or more specifically, 0.01 to 0.3 parts by weight, per 100 parts by weight of the total monomer. As the polar additive, for example, one or more selected from the group consisting of tetrahydrofuran, ditetrahydrofurylpropane, diethyl ether, cycloamal ether, dipropyl ether, ethylene dimethyl ether, ethylene dimethyl ether, diethyl glycol, dimethyl ether, tertiary butoxyethoxyethane, bis(3-dimethylaminoethyl) ether, (dimethylaminoethyl)ethyl ether, trimethylamine, triethylamine, tripropylamine, and tetramethylethylenediamine can be used.

[0063] Furthermore, in the above-described manufacturing method, when copolymerizing a conjugated diene monomer and an aromatic vinyl monomer by using the aforementioned polar additive, it is possible to easily form a random copolymer by compensating for the difference in their reaction rates.

[0064] Furthermore, the polymerization in step 1) above can be carried out via adiabatic polymerization or isothermal polymerization. Here, the adiabatic polymerization method includes a step in which polymerization is carried out by the heat of self-reaction without adding any heat after the organoalkali metal compound has been added, and the isothermal polymerization method includes a step in which the temperature of the polymer is kept constant by adding or removing heat after the organoalkali metal compound has been added.

[0065] Furthermore, the polymerization may be carried out in a temperature range of 20°C to 200°C, more specifically in a temperature range of 0°C to 150°C, and more specifically in a temperature range of 10°C to 120°C.

[0066] Furthermore, step 2) above is a modification reaction step in which the active polymer is reacted with a modifying agent containing the compound represented by formula (1) in order to produce a modified copolymer.

[0067] In this case, the modifying agent containing the compound represented by formula (1) may be the same as that described above. The compound represented by formula (1) can be used in a ratio of 0.1 to 2.0 moles per mole of the organoalkali metal compound. Furthermore, the reaction in step 2) above is a modification reaction to introduce functional groups into the polymer, and each of the reactions may be carried out at a temperature range of 0°C to 90°C for 1 minute to 5 hours.

[0068] Furthermore, the above-described manufacturing method may, if necessary, further include one or more steps after step 2) above, such as solvent collection, recovery of unreacted monomers, and drying.

[0069] Furthermore, as described above, the modified copolymer is modified with a modifying agent containing the compound represented by formula (1), but it is preferable that it be further modified with a modifying agent containing the compound represented by formula (2). This further improves the dispersibility of the filler in the rubber composition, thereby achieving a higher level of both low heat generation and handling stability when applied to tires, and also improves wear resistance and processability.

[0070] [ka] In formula (2) above, R1 to R3 are independently of each other: hydrogen; C1 to C30 alkyl group; C2 to C30 alkenyl group; C2 to C30 alkynyl group; C1 to C30 heteroalkyl group, C2 to C30 heteroalkenyl group; C2 to C30 heteroalkynyl group; C5 to C30 cycloalkyl group; C6 to C30 aryl group; or C3 to C30 heterocyclic group, and R4 is a single bond; C1 to C20 alkylene group with substituted or unsubstituted substituents; C5 to C20 cycloalkylene group with substituted or unsubstituted substituents; or C5 to C20 arylene group with substituted or unsubstituted substituents, where the substituents are C1 to C10 alkyl group, C5 to R5 is a cycloalkyl group of 10 or an aryl group having 6 to 20 carbon atoms, where R5 is an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; a heterocyclic group having 3 to 30 carbon atoms; or an active group represented by the following chemical formula (2a) or chemical formula (2b), where n is an integer from 1 to 5, and at least one of R5 is an active group represented by the following chemical formula (2a) or chemical formula (2b), and when n is an integer from 2 to 5, multiple R5s may be the same as or different from each other.

[0071] [ka] In formula (2a) above, R6 is a C1-C20 alkylene group with a substituent substituted or unsubstituted; a C5-C20 cycloalkylene group with a substituent substituted or unsubstituted; or a C6-C20 arylene group with a substituent substituted or unsubstituted, where the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group, and R7 and R8 are independently a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C2 R9 is a C1-C20 alkylene group substituted or unsubstituted on an aryl group, where R9 is hydrogen; a C1-C30 alkyl group; a C2-C30 alkenyl group; a C2-C30 alkynyl group; a C1-C30 heteroalkyl group; a C2-C30 heteroalkenyl group; a C2-C30 heteroalkynyl group; a C5-C30 cycloalkyl group; a C6-C30 aryl group; or a C3-C30 heterocyclic group, where X is an N, O, or S atom, and if X is O or S, R9 is absent.

[0072] [ka] In the above equation (2b), R 10 R is a C1-C20 alkylene group with a substituent that is substituted or unsubstituted; a C5-C20 cycloalkylene group with a substituent that is substituted or unsubstituted; or a C6-C20 arylene group with a substituent that is substituted or unsubstituted, where the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group, 11 and R 12 These are, independently of each other, alkyl groups having 1 to 30 carbon atoms; alkenyl groups having 2 to 30 carbon atoms; alkynyl groups having 2 to 30 carbon atoms; heteroalkyl groups having 1 to 30 carbon atoms; heteroalkenyl groups having 2 to 30 carbon atoms; heteroalkynyl groups having 2 to 30 carbon atoms; cycloalkyl groups having 5 to 30 carbon atoms; aryl groups having 6 to 30 carbon atoms; and heterocyclic groups having 3 to 30 carbon atoms.

[0073] Furthermore, in the compound represented by formula (2) above, R1 to R3 are independently hydrogen; a C1-C10 alkyl group; a C2-C10 alkenyl group; or a C2-C10 alkynyl group; R4 is a single bond; or an unsubstituted C1-C10 alkylene group; R5 is a C1-C10 alkyl group; a C2-C10 alkenyl group; a C2-C10 alkynyl group; or the compound represented by the following chemical formula (2a) or R is an active group represented by chemical formula (2b), in the above chemical formula (2a), R6 is an unsubstituted alkylene group having 1 to 10 carbon atoms, R7 and R8 are independently unsubstituted alkylene groups having 1 to 10 carbon atoms, R7 is an alkyl group having 1 to 10 carbon atoms; a cycloalkyl group having 5 to 20 carbon atoms; an aryl group having 6 to 20 carbon atoms; or a heterocyclic group having 3 to 20 carbon atoms, in the above chemical formula (2b), R 10 R is an unsubstituted alkylene group having 1 to 10 carbon atoms. 11 and R 12 These may be, independently of each other, an alkyl group having 1 to 10 carbon atoms; a cycloalkyl group having 5 to 20 carbon atoms; an aryl group having 6 to 20 carbon atoms; or a heterocyclic group having 3 to 20 carbon atoms.

[0074] More specifically, the compound represented by formula (2) above can be the compound represented by the following formulas (2-1) to (2-3).

[0075] [ka]

[0076] Furthermore, when the copolymer is modified with a modifying agent containing the compound represented by formula (2), the modifying agent containing the compound represented by formula (2) is used as a modification initiator. Specifically, for example, by polymerizing a conjugated diene monomer and an aromatic vinyl monomer in a hydrocarbon solvent in the presence of a modifying agent containing the compound represented by formula (2), a modifying group derived from the compound represented by formula (2) can be imparted to the copolymer.

[0077] Here, the polymerization of the conjugated diene monomer and the aromatic vinyl monomer can be, for example, anionic polymerization. Specifically, it may be living anionic polymerization, in which an anionic active site is formed at the polymerization end by an anionic growth polymerization reaction. Furthermore, the polymerization may be temperature-increasing polymerization, isothermal polymerization, or constant-temperature polymerization (adiabatic polymerization). Constant-temperature polymerization means a polymerization method that includes a step of polymerization by self-reaction heat without arbitrarily adding heat after adding a modifying agent containing the compound represented by formula (2). Temperature-increasing polymerization means a polymerization method in which the temperature is increased by arbitrarily adding heat after adding a modifying initiator. Isothermal polymerization means a polymerization method in which the temperature of the polymer is kept constant by adding heat to increase the heat or by removing heat after adding the modifying initiator.

[0078] The content of the modified copolymer in the rubber component (A) is not particularly limited, but can be 0.1 to 90% by mass, preferably 10 to 90% by mass, and more preferably 20 to 80% by mass. When the content of the modified copolymer is 0.1% by weight or more, the low heat generation property can be improved while maintaining other physical properties well, and as a result, the effects such as fuel efficiency, wear characteristics, and braking characteristics of molded articles manufactured using the rubber composition, such as tires, can be more reliably obtained.

[0079] (Filler) The rubber composition produced by the manufacturing method of the present invention contains a filler containing an inorganic filler (B). Here, as the inorganic filler (B), for example, silica and an inorganic compound represented by the following general formula (XI) can be used. dM 1 ·xSiO y ·zH2O ···(XI) Here, in general formula (XI), M1 is at least one selected from the group consisting of aluminum, magnesium, titanium, calcium, and zirconium, oxides or hydroxides of these metals, hydrates thereof, or carbonates of these metals; d, x, y, and z are integers of 1 to 5, integers of 0 to 10, integers of 2 to 5, and integers of 0 to 10, respectively. In general formula (XI), when both x and z are 0, the inorganic compound becomes at least one metal, metal oxide, or metal hydroxide selected from aluminum, magnesium, titanium, calcium, and zirconium.

[0080] In the present invention, among the above-mentioned inorganic fillers (B), silica is preferable from the viewpoint of achieving both low rolling resistance and abrasion resistance. Any commercially available silica can be used, and among them, it is preferable to use wet silica, dry silica, or colloidal silica, and it is particularly preferable to use wet silica. The BET specific surface area of silica (measured in accordance with ISO5794 / 1) is preferably 40 to 350 m 2 / g. Silica having a BET surface area within this range has the advantage of being able to achieve both rubber reinforcing properties and dispersibility in the rubber component. From this viewpoint, silica having a BET surface area in the range of 80 to 350 m 2 / g is more preferable, and silica having a BET surface area in the range of 120 to 350 m 2 / g is particularly preferable. Commercially available products such as "Nipsil AQ" (BET specific surface area = 220 m 2 / g), "Nipsil KQ" manufactured by Tosoh Silica Corporation, and "Ultrasil VN3" (BET specific surface area = 175 m 2 / g) manufactured by Degussa AG can be used as such silica.

[0081] Inorganic compounds represented by the general formula (XI) include alumina (Al2O3) such as γ-alumina and α-alumina, alumina monohydrate (Al2O3·H2O) such as boehmite and diaspore, aluminum hydroxide [Al(OH)3] such as gibbsite and bayerite, aluminum carbonate [Al2(CO3)2], magnesium hydroxide [Mg(OH)2], magnesium oxide (MgO), magnesium carbonate (MgCO3), talc (3MgO·4SiO2·H2O), attapulgite (5MgO·8SiO2·9H2O), titanium white (TiO2), and titanium black (TiO2). 2n―1 ), calcium oxide (CaO), calcium hydroxide [Ca(OH)2], magnesium aluminum oxide (MgO·Al2O3), clay (Al2O3·2SiO2), kaolin (Al2O3·2SiO2·2H2O), pyrophyllite (Al2O3·4SiO2·H2O), bentonite (Al2O3·4SiO2·2H2O), aluminum silicate (Al2SiO5, Al4·3SiO4·5H2O, etc.), magnesium silicate (Mg2SiO4, MgSiO3, etc.), Calcium silicate (Ca2·SiO4, etc.), aluminum calcium silicate (Al2O3·CaO·2SiO2, etc.), magnesium calcium silicate (CaMgSiO4), calcium carbonate (CaCO3), zirconium oxide (ZrO2), zirconium hydroxide [ZrO(OH)2·nH2O], zirconium carbonate [Zr(CO3)2], and crystalline aluminosilicates containing hydrogen, alkali metals, or alkaline earth metals to correct the charge, such as various zeolites, can be used. Furthermore, it is preferable that M1 in the above general formula (XI) is at least one selected from aluminum metal, aluminum oxides or hydroxides, their hydrates, or aluminum carbonates. These inorganic compounds represented by general formula (XI) may be used individually or in combination of two or more. The average particle size of these inorganic compounds is preferably in the range of 0.01 to 10 μm, and more preferably in the range of 0.05 to 5 μm, from the viewpoint of balancing kneadability, abrasion resistance, and wet grip performance. The inorganic filler (B) in the present invention may be silica alone or silica and general formula (III) may be used in combination with one or more inorganic compounds represented by (III).

[0082] Furthermore, the filler may optionally contain carbon black in addition to the inorganic filler (B) described above. By including carbon black, the reinforcing properties of the rubber composition can be enhanced, and better abrasion resistance can be obtained. There are no particular restrictions on the carbon black, but for example, carbon black of high, medium, or low structure grades such as SAF, ISAF, IISAF, N339, HAF, FEF, GPF, and SRF is preferred, and in particular, carbon black of SAF, ISAF, IISAF, N339, HAF, and FEF grades is preferred. Nitrogen adsorption specific surface area (N2SA, measured in accordance with JIS K6217-2:2001) is 30 to 250 m². 2 It is preferable that the amount is / g. This carbon black may be used alone or in combination of two or more types. Note that in this invention, carbon black is not included in the inorganic filler (B).

[0083] In the manufacturing method of the present invention, it is preferable to use 20 to 120 parts by mass of the inorganic filler (B) per 100 parts by mass of the rubber component (A). Using 20 parts by mass or more is preferable from the viewpoint of ensuring wet performance, and using 120 parts by mass or less is preferable from the viewpoint of improving low heat generation. Furthermore, using 30 to 100 parts by mass is even more preferable. Furthermore, it is preferable to use 20 to 150 parts by mass of the filler per 100 parts by mass of rubber component (A). A value of 20 parts by mass or more is preferable from the viewpoint of improving the reinforcing properties of the rubber composition, while a value of 150 parts by mass or less is preferable from the viewpoint of improving low heat generation. Furthermore, it is preferable that the inorganic filler (B) in the filler is 40% by mass or more from the viewpoint of achieving both wet performance and low heat generation, and it is even more preferable that it is 70% by mass or more.

[0084] (Silane coupling agent) The rubber composition produced by the manufacturing method of the present invention contains a silane coupling agent (C). Here, the silane coupling agent (C) is preferably at least one compound selected from the group consisting of compounds represented by the following general formulas (I) to (IV). The rubber composition produced by the manufacturing method of the present invention, when using such a silane coupling agent (C), provides even better workability during rubber processing and a more wear-resistant pneumatic tire. It can give.

[0085] [ka] In the formula, R 1 They may be the same or different, and each may be a linear, cyclic, or branched alkyl group having 1 to 8 carbon atoms, or a linear or branched alkoxyalkyl group having 2 to 8 carbon atoms, R 2 They may be the same or different, and each may be a linear, cyclic, or branched alkyl group with 1 to 8 carbon atoms, R 3 The groups may be the same or different, each being a linear or branched alkylene group with 1 to 8 carbon atoms, a having an average value of 2 to 6, and p and r may be the same or different, each having an average value of 0 to 3, however, both p and r cannot be 3.

[0086] Specific examples of the silane coupling agent (C) represented by the general formula (I) above include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(3-methyldimethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(3-methyldimethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-trimethoxysilylpropyl)trisulfide, bis(3-methyldimethoxysilylpropyl)trisulfide, bis(2-triethoxysilylethyl)trisulfide, bis(3-monoethoxydimethylsilylpropyl)tetrasulfide, bis(3-monoethoxydimethylsilylpropyl)trisulfide, bis(3-monoethoxydimethylsilylpropyl)disulfide, bis(3-monomethoxydimethylsilylpropyl)tetrasulfide, bis(3-monomethoxydimethylsilylpropyl)trisulfide, bis(3-monomethoxydimethylsilylpropyl)disulfide, bis(2-monoethoxydimethylsilylethyl)tetrasulfide, bis(2-monoethoxydimethylsilylethyl)trisulfide, bis(2-monoethoxydimethylsilylethyl)disulfide, etc.

[0087]

Chemical formula

[0088] In the above general formula (II), R 8 , R 9 , R 10 and R 11 These may be the same or different, and preferably each is a group selected from the group consisting of linear, cyclic, or branched alkyl groups, alkenyl groups, aryl groups, and aralkyl groups having 1 to 18 carbon atoms. Furthermore, if R5 is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is preferable that it is a group selected from the group consisting of linear, cyclic, or branched alkyl groups, alkenyl groups, aryl groups, and aralkyl groups. 12 The alkylene group is preferably linear, cyclic, or branched, and is particularly preferred to be linear. 9Examples of these include alkylene groups having 1 to 18 carbon atoms, alkenylene groups having 2 to 18 carbon atoms, cycloalkylene groups having 5 to 18 carbon atoms, cycloalkylalkylene groups having 6 to 18 carbon atoms, arylene groups having 6 to 18 carbon atoms, and aralkylene groups having 7 to 18 carbon atoms. The alkylene groups and alkenylene groups may be linear or branched, and the cycloalkylene groups, cycloalkylalkylene groups, arylene groups, and aralkylene groups may have substituents such as lower alkyl groups on the ring. 7 Preferably, the alkylene group has 1 to 6 carbon atoms, and in particular, linear alkylene groups such as methylene, ethylene, trimethylene, tetramethylene, pentamethylene, and hexamethylene groups are preferred.

[0089] In the above general formula (II), R 5 , R 8 , R 9 , R 10 and R 11 Specific examples of monovalent hydrocarbon groups with 1 to 18 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, vinyl group, propenyl group, allyl group, hexenyl group, octenyl group, cyclopentenyl group, cyclohexenyl group, phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenethyl group, naphthylmethyl group, and the like. In the above general formula (II), R 12 Examples include methylene groups, ethylene groups, trimethylene groups, tetramethylene groups, pentamethylene groups, hexamethylene groups, octamethylene groups, decamethylene groups, dodecamethylene groups, and so on.

[0090] Specific examples of the silane coupling agent (C) represented by the general formula (II) above include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, and 2-lauroylthioethyltrimethoxysilane. Of these, 3-octanoylthiopropyltriethoxysilane (manufactured by General Electric Silicones, trademark: NXT silane) is particularly preferred.

[0091] [ka] In the formula, R 13 If there are multiple elements, they may be the same or different, and each is a linear, cyclic, or branched alkyl group having 1 to 8 carbon atoms, a linear or branched alkoxyalkyl group having 2 to 8 carbon atoms, or a hydrogen atom, R 14 If there are multiple elements, they may be the same or different, and each is a linear, cyclic, or branched alkyl group having 1 to 8 carbon atoms, R 15 If there are multiple elements, they may be the same or different, and each is a linear or branched alkylene group with 1 to 8 carbon atoms. 16 The general formula is (-SR 17 -S-), (-R 18 -S m1 -R 19 -) and (-R 20 -S m2 -R 21 -S m3 -R 22-) any of the divalent groups (R 17 ~R 22 Each of the following is a divalent hydrocarbon group, a divalent aromatic group, or a divalent organic group containing a heteroatom other than sulfur and oxygen, with m1, m2, and m3 each having an average value of 1 or more and less than 4. The multiple k values ​​may be the same or different, each having an average value of 1 to 6, and s and t each having an average value of 0 to 3. However, both s and t cannot be 3.

[0092] As a specific example of the silane coupling agent (C) represented by the general formula (III) above, Average composition formula (CH3CH2O)3Si-(CH2)3-S2-(CH2)6-S2-(CH2)3- Si(OCH2CH3)3, Average composition formula (CH3CH2O)3Si-(CH2)3-S2-(CH2) 10 -S2-(CH2)3- Si(OCH2CH3)3, Average composition formula (CH3CH2O)3Si-(CH2)3-S3-(CH2)6-S3-(CH2)3- Si(OCH2CH3)3, Average composition formula (CH3CH2O)3Si-(CH2)3-S4-(CH2)6-S4-(CH2)3- Si(OCH2CH3)3, Average composition formula (CH3CH2O)3Si-(CH2)3-S-(CH2)6-S2-(CH2)6-S -(CH2)3-Si(OCH2CH3)3, Average composition formula (CH3CH2O)3Si-(CH2)3-S-(CH2)6-S 2.5 -(CH2)6- S-(CH2)3-Si(OCH2CH3)3, Average composition formula (CH3CH2O)3Si-(CH2)3-S-(CH2)6-S3-(CH2)6-S -(CH2)3-Si(OCH2CH3)3, Average composition formula (CH3CH2O)3Si-(CH2)3-S-(CH2)6-S 4- (CH2)6-S -(CH2)3-Si(OCH2CH3)3, Average composition formula (CH3CH2O)3Si-(CH2)3-S-(CH2) 10 -S2-(CH2) 10 - S-(CH2)3-Si(OCH2CH3)3, Average composition formula (CH3CH2O)3Si-(CH2)3-S4-(CH2)6-S 4- (CH2)6- S4-(CH2)3-Si(OCH2CH3)3, Average composition formula (CH3CH2O)3Si-(CH2)3-S2-(CH2)6-S2-(CH2)6- S2-(CH2)3-Si(OCH2CH3)3, Average composition formula (CH3CH2O)3Si-(CH2)3-S-(CH2)6-S2-(CH2)6-S Compounds represented as 2-(CH2)6-S-(CH2)3-Si(OCH2CH3)3, etc., are preferred examples.

[0093] [ka] In the formula, R 23 G is a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, and the multiple Gs may be the same or different, each being an alkanediyl or alkenediyl group having 1 to 9 carbon atoms, and the multiple Zs a These may be the same or different, and each is a functional group capable of bonding to two silicon atoms, and [-0-] 0.5 [-0-G-] 0.5 and [-OGO-] 0.5 A functional group selected from among several Z b These may be the same or different, and each is a functional group capable of bonding to two silicon atoms, and [-OGO-] 0.5 It is a functional group represented by Z, and there are multiple Z c These can be the same or different, and are -Cl, -Br, and -OR respectively. a , R a C(=O)O-, R a R b C=NO-, Ra R b N-, R a - and HO-GO- (G matches the above notation) are selected functional groups, R b and R b Each of these is a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms. m, n, u, v, and w satisfy 1 ≤ m ≤ 20, 0 ≤ n ≤ 20, 0 ≤ u ≤ 3, 0 ≤ v ≤ 2, 0 ≤ w ≤ 1, and (u / 2) + v + 2w = 2 or 3. If there are multiple A parts, Z in the multiple A parts. a u , Z b v and Z c w In each case, they may be the same or different, and if there are multiple parts B, Z in the multiple parts B a u , Z b v and Z c w In each case, they may be the same or different.

[0094] Specific examples of the silane coupling agent (C) represented by the general formula (IV) above include chemical formulas (V), (IV), and (VII). [ka] [ka] [ka] In the formula, L is independently an alkanediyl group or alkenediyl group having 1 to 9 carbon atoms, where x=m and y=n.

[0095] As a silane coupling agent represented by chemical formula (V), Momentive Performance Materials, under the trademark "NXT Low-VSilane," is commercially available. Furthermore, a silane coupling agent represented by chemical formula (VI), "NXT Ultra Low-VSilane" manufactured by Momentive Performance Materials, is also available commercially. Furthermore, an example of a silane coupling agent represented by chemical formula (VII) is "NXT-Z," a trademark of Momentive Performance Materials. The silane coupling agents obtained by the above general formula (II), chemical formula (V), and chemical formula (VI) have protected mercapto groups, which prevents the occurrence of initial vulcanization (scorching) during processing in steps prior to the vulcanization process, thus resulting in good processability. Furthermore, the silane coupling agents obtained by chemical formulas (V), (VI), and (VII) are preferable from a working environment perspective because they have a large number of alkoxysilane carbon atoms, resulting in less generation of volatile organic compounds (VOCs), especially alcohols. Moreover, the silane coupling agent of chemical formula (VII) is even more preferable because it provides low heat generation as a tire performance characteristic.

[0096] Furthermore, among the compounds represented by the above general formulas (I) to (IV), the silane coupling agent (C) is particularly preferred if it is the compound represented by general formula (I). This is because the vulcanization accelerator (D) readily activates the polysulfide bond site that reacts with the rubber component (A). In the present invention, the silane coupling agent (C) may be used alone or in combination of two or more types. Furthermore, the amount of silane coupling agent (C) in the rubber composition is preferably such that the mass ratio {silane coupling agent (C) / inorganic filler (B)} is (1 / 100) to (20 / 100). If it is (1 / 100) or more, the effect of improving the low heat generation of the rubber composition is more favorably exhibited, and if it is (20 / 100) or less, the cost of the rubber composition is reduced and the economic efficiency is improved. Moreover, a mass ratio of (3 / 100) to (20 / 100) is more preferable, and a mass ratio of (4 / 100) to (10 / 100) is particularly preferable.

[0097] (Vulcanization accelerator) The rubber composition produced by the manufacturing method of the present invention contains a vulcanization accelerator (D). The following will be detailed descriptions of preferred vulcanization accelerators (D) that include guanidines, sulfenamides, thiazoles, thiurams, dithiocarbamates, thioureas, and xanthogenic salts.

[0098] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salts of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine. 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, and 1-o-tolylbiguanide are preferred due to their high reactivity.

[0099] Examples of sulfurization accelerators for the sulfenamides include N-cyclohexyl-2-benzothiazolylsulfenamide, N,N-dicyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzothiazolylsulfenamide, N-oxydiethylene-2-benzothiazolylsulfenamide, N-methyl-2-benzothiazolylsulfenamide, N-ethyl-2-benzothiazolylsulfenamide, N-propyl-2-benzothiazolylsulfenamide, N-butyl-2-benzothiazolylsulfenamide, N-pentyl-2-benzothiazolylsulfenamide, N-hexyl-2-benzothiazolylsulfenamide, N-pentyl-2-benzothiazolylsulfenamide, N-octyl-2-benzothiazolylsulfenamide, N-2-ethylhexyl-2-benzothiazolylsulfenamide, N-decyl-2-benzothiazolylsulfenamide, N-dodecyl-2-benzothiazolyl sulfenamide, N-stearyl-2-benzothiazolyl sulfenamide, N,N-dimethyl-2-benzothiazolyl sulfenamide, N,N-diethyl-2-benzothiazolyl sulfenamide, N,N-dipropyl-2-benzothiazolyl sulfenamide, N,N-dibutyl-2-benzothiazolyl sulfenamide, N,N-dipentyl-2-benzothiazolyl sulfenamide, N,N-dihexyl Examples include cyl-2-benzothiazolyl sulfenamide, N,N-dipentyl-2-benzothiazolyl sulfenamide, N,N-dioctyl-2-benzothiazolyl sulfenamide, N,N-di-2-ethylhexylbenzothiazolyl sulfenamide, N-decyl-2-benzothiazolyl sulfenamide, N,N-didodecyl-2-benzothiazolyl sulfenamide, and N,N-distearyl-2-benzothiazolyl sulfenamide. Of these, N-cyclohexyl-2-benzothiazolyl sulfenamide and N-tert-butyl-2-benzothiazolyl sulfenamide are preferred due to their high reactivity.

[0100] Examples of vulcanization accelerators for the thiazoles include 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, zinc salt of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, 2-(N,N-diethylthiocarbamoylthio)benzothiazole, 2-(4'-morpholinodithio)benzothiazole, 4-methyl-2-mercaptobenzothiazole, di-(4-methyl-2-benzothiazolyl) disulfide, 5-chloro-2-mercaptobenzothiazole, sodium 2-mercaptobenzothiazole, 2-mercapto-6-nitrobenzothiazole, 2-mercapto-naphtho[1,2-d]thiazole, 2-mercapto-5-methoxybenzothiazole, and 6-amino-2-mercaptobenzothiazole. Of these, 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide are preferred due to their high reactivity.

[0101] Examples of thiram-based vulcanization accelerators include tetramethylthiram disulfide, tetraethylthiram disulfide, tetrapropylthiram disulfide, tetraisopropylthiram disulfide, tetrabutylthiram disulfide, tetrapentylthiram disulfide, tetrahexylthiram disulfide, tetraheptylthiram disulfide, tetraoctylthiram disulfide, tetranonylthiram disulfide, tetradecylthiram disulfide, tetradodecylthiram disulfide, tetrastearylthiram disulfide, tetrabenzylthiram disulfide, and tetrakis(2-ethylhexyl). Examples include thiuram disulfide, tetramethyl thiuram monosulfide, tetraethyl thiuram monosulfide, tetrapropyl thiuram monosulfide, tetraisopropyl thiuram monosulfide, tetrabutyl thiuram monosulfide, tetrapentyl thiuram monosulfide, tetrahexyl thiuram monosulfide, tetraheptyl thiuram monosulfide, tetraoctyl thiuram monosulfide, tetranonyl thiuram monosulfide, tetradecyl thiuram monosulfide, tetradodecyl thiuram monosulfide, tetrastearyl thiuram monosulfide, tetrabenzyl thiuram monosulfide, and dipentamethylenethiuram tetrasulfide. Of these, tetrakis(2-ethylhexyl) thiuram disulfide and tetrabenzyl thiuram disulfide are preferred due to their high reactivity.

[0102] Examples of vulcanization accelerators for the thioureas include N,N'-diphenylthiourea, trimethylthiourea, N,N'-diethylthiourea, N,N'-dimethylthiourea, N,N'-dibutylthiourea, ethylenethiourea, N,N'-diisopropylthiourea, N,N'-dicyclohexylthiourea, 1,3-di(o-tolyl)thiourea, 1,3-di(p-tolyl)thiourea, 1,1-diphenyl-2-thiourea, 2,5-dithiobiurea, guanylthiourea, 1-(1-naphthyl)-2-thiourea, 1-phenyl-2-thiourea, p-tolylthiourea, and o-tolylthiourea. Of these, N,N'-diethylthiourea, trimethylthiourea, N,N'-diphenylthiourea, and N,N'-dimethylthiourea are preferred due to their high reactivity.

[0103] Examples of the dithiocarbamate salts used as vulcanization accelerators include zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dipropyldithiocarbamate, zinc diisopropyldithiocarbamate, zinc dibutyldithiocarbamate, zinc dipentyldithiocarbamate, zinc dihexyldithiocarbamate, zinc diheptyldithiocarbamate, zinc dioctyldithiocarbamate, zinc di(2-ethylhexyl)dithiocarbamate, zinc didecyldithiocarbamate, zinc didodecyldithiocarbamate, and N-pentamethylenedithiocarbamate. Zinc occarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc dibenzyldithiocarbamate, copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dipropyldithiocarbamate, copper diisopropyldithiocarbamate, copper dibutyldithiocarbamate, copper dipentyldithiocarbamate, copper dihexyldithiocarbamate, copper diheptyldithiocarbamate, copper dioctyldithiocarbamate, copper di(2-ethylhexyl)dithiocarbamate, copper didecyldithiocarbamate, didodecyldithiocarbamate Copper oxide, copper N-pentamethylenedithiocarbamate, copper dibenzyldithiocarbamate, sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate, sodium dipropyldithiocarbamate, sodium diisopropyldithiocarbamate, sodium dibutyldithiocarbamate, sodium dipentyldithiocarbamate, sodium dihexyldithiocarbamate, sodium diheptyldithiocarbamate, sodium dioctyldithiocarbamate, sodium di(2-ethylhexyl)dithiocarbamate , sodium didecyl dithiocarbamate, sodium didodecyl dithiocarbamate, sodium N-pentamethylene dithiocarbamate, sodium dibenzyl dithiocarbamate, ferric dimethyldithiocarbamate, ferric diethyldithiocarbamate, ferric dipropyldithiocarbamate, ferric diisopropyldithiocarbamate, ferric dibutyldithiocarbamate, ferric dipentyldithiocarbamate, ferric dihexyldithiocarbamate, ferric diheptyldithiocarbamate, ferric dioctyldithiocarbamate,Examples include ferric di(2-ethylhexyl)dithiocarbamate, ferric didecyldithiocarbamate, ferric didodecyldithiocarbamate, ferric N-pentamethylenedithiocarbamate, and ferric dibenzyldithiocarbamate. Of these, zinc dibenzyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc dimethyldithiocarbamate, and copper dimethyldithiocarbamate are preferred due to their high reactivity.

[0104] Examples of the xanthogenic acid sulfurization accelerators include zinc methylxanthonate, zinc ethylxanthonate, zinc propylxanthonate, zinc isopropylxanthonate, zinc butylxanthonate, zinc pentylxanthonate, zinc hexylxanthonate, zinc heptylxanthonate, zinc octylxanthonate, zinc 2-ethylhexylxanthonate, zinc decylxanthonate, zinc dodecylxanthonate, potassium methylxanthonate, potassium ethylxanthonate, potassium propylxanthonate, potassium isopropylxanthonate, potassium butylxanthonate, potassium pentylxanthonate, and potassium hexylxanthonate. Examples include zinc, heptylxanthogenic acid potassium, octylxanthogenic acid potassium, 2-ethylhexylxanthogenic acid potassium, decylxanthogenic acid potassium, dodecylxanthogenic acid potassium, sodium methylxanthogenic acid sodium, sodium ethylxanthogenic acid sodium, sodium propylxanthogenic acid sodium, sodium isopropylxanthogenic acid sodium, sodium butylxanthogenic acid sodium, sodium pentylxanthogenic acid sodium, sodium hexylxanthogenic acid sodium, heptylxanthogenic acid sodium, sodium octylxanthogenic acid sodium, 2-ethylhexylxanthogenic acid sodium, decylxanthogenic acid sodium, and sodium dodecylxanthogenic acid sodium. Of these, zinc isopropylxanthogenic acid is preferred due to its high reactivity.

[0105] Furthermore, in the manufacturing method of the present invention, it is preferable to use at least one guanidine-based vulcanization accelerator or at least one thiourea-based vulcanization accelerator among the various vulcanization accelerators described above, and it is more preferable to use at least one guanidine-based vulcanization accelerator. The modified copolymer in the rubber component (A) tends to have increased viscosity when both ends are modified, but by using the guanidine vulcanization accelerator, the increase in viscosity can be suppressed, resulting in better processability.

[0106] In the manufacturing method of the present invention, it is preferable that the number of molecules (moles) of the vulcanization accelerator (D) in the rubber composition in the first kneading stage is 0.1 to 1.0 times the number of molecules (moles) of the silane coupling agent (C). This is because if it is 0.1 times or more, the silane coupling agent (C) is sufficiently activated, and if it is 1.0 times or less, it does not have a significant effect on the vulcanization rate. More preferably, the number of molecules (moles) of the vulcanization accelerator (D) is 0.2 to 0.6 times the number of molecules (moles) of the silane coupling agent (C). Furthermore, since the vulcanization accelerator (D) is also used as an accelerator for sulfur vulcanization, an appropriate amount may be added as desired in the final stage of mixing. When adding the vulcanization accelerator in the final stage of mixing, it is not limited to the vulcanization accelerator (D) described above, but any known vulcanization accelerator may be added.

[0107] (organic acid compound) In the manufacturing method of the present invention, it is preferable that the number of molecules (moles) of the organic acid compound in the rubber composition in the first kneading stage is 1.5 times or less the number of molecules (moles) of the vulcanization accelerator (D). This is to suitably suppress the reduction of the coupling function enhancement effect due to the inclusion of the vulcanization accelerator (D).

[0108] Examples of the aforementioned organic acid compounds include saturated and unsaturated fatty acids such as stearic acid, palmitic acid, myristic acid, lauric acid, arachidic acid, behenic acid, lignoceric acid, capric acid, pelargonic acid, caprylic acid, enanthic acid, caproic acid, oleic acid, vaccenic acid, linoleic acid, linolenic acid, and nervonic acid, as well as organic acids such as resin acids such as rosinic acid and modified rosinic acid, and esters of the aforementioned saturated and unsaturated fatty acids and resin acids. Furthermore, in the present invention, it is preferable that stearic acid accounts for 50 mol% or more of the organic acid compound in the rubber composition at the first stage of kneading, as it can also fully exhibit its function as a vulcanization accelerator. Furthermore, if the rubber component (A) includes at least one selected from emulsion polymerized styrene-butadiene copolymer and natural rubber, it is preferable that 50 mol% or more of the organic acid compound in the rubber composition in the first stage of kneading is at least one compound selected from rosin acid and fatty acids, which are included in the emulsion polymerized styrene-butadiene copolymer and at least one selected from natural rubber. The rosin acid (including modified rosin acid) and fatty acids included in the emulsion polymerized styrene-butadiene copolymer are derived from emulsifiers necessary for polymerizing the emulsion polymerized styrene-butadiene copolymer. Also, natural rubber usually contains small amounts of fatty acids.

[0109] (Other ingredients) Furthermore, the rubber composition produced by the manufacturing method of the present invention may contain, in addition to the rubber component (A), an inorganic filler (B), a silane coupling agent (C), a vulcanization accelerator (D), etc., other compounding components commonly used in the rubber industry, such as antioxidants and softeners, selected as appropriate within a range that does not impair the purpose of the present invention and in a range of normal compounding amounts. Commercially available products can be suitably used as these compounding agents.

[0110] The aforementioned antioxidant can be any known type and is not particularly limited. Examples include phenolic antioxidants, imidazole antioxidants, amine antioxidants, etc. One or more of these antioxidants can be used in combination.

[0111] Furthermore, the rubber composition produced by the manufacturing method of the present invention preferably further contains a softening agent from the viewpoint of achieving excellent low loss and wear resistance. Examples of the softening agent include naphthenic base oils, paraffinic base oils, aromatic base oils, etc. Here, the amount of lubricant is preferably 2 to 30 parts by mass per 100 parts by mass of the rubber component. If the amount of lubricant exceeds 30 parts by mass per 100 parts by mass of the rubber component, there is a risk that the lubricant may seep out onto the surface of the rubber product or that the wear resistance may decrease. In addition, it may interact with and shield the tetrazine moiety in the modified rubber component, reducing its reactivity and potentially decreasing its low loss performance and wear resistance. Furthermore, among the lubricants mentioned above, naphthenic base oils or paraffinic base oils are preferred, with naphthenic base oils being the most preferred. Aromatic oils are undesirable because they contain many aromatic components, which gives them a high affinity for the aromatic compounds in question, thus further inhibiting the reaction with the polymer. On the other hand, naphthenic and paraffinic base oils have the effect of helping to diffuse and react within the polymer, and oils with lower pour points diffuse better into the polymer. The classification of naphthenic base oils, paraffinic base oils, and aromatic base oils is determined by the CA value, CP value, and CN value. For example, naphthenic base oils include TDAE, SRAE, RAE, and Black Oil. Paraffinic base oils include spindle oil and paraffin oil. Furthermore, even more favorable effects can be obtained with a mixed oil such as A / O Mix (Sankyo Yuka Kogyo Co., Ltd.), which is a mixture of the naphthenic base oil and the naphthenic asphalt. The timing of the addition of these lubricants is not particularly limited; for example, they may be added during the manufacturing stage of the rubber component, or they may be added when the rubber composition is kneaded.

[0112] Furthermore, in the method for producing the rubber composition of the present invention, various additives such as vulcanizing activators like zinc oxide and antioxidants, which are usually incorporated into the rubber composition, are mixed in as needed in the first or final stage of mixing, or in an intermediate stage between the first and final stages. In the manufacturing method of the present invention, kneading equipment such as a Banbury mixer, rolls, intensive mixer, kneader, and twin-screw extruder can be used.

[0113] <Rubber composition> The rubber composition of the present invention is characterized by being obtained by the method for producing the rubber composition of the present invention described above. The rubber composition obtained by the manufacturing method according to the present invention exhibits high dispersibility of fillers and excellent low loss properties.

[0114] <Tires> The tire of the present invention is characterized by using the rubber composition of the present invention described above. By including the rubber composition of the present invention as a tire material, it is possible to reduce rolling resistance. Furthermore, the tire of the present invention is not particularly limited except that the rubber composition of the present invention described above is used in one of the tire components, and can be manufactured according to conventional methods. In addition to ordinary air or air with adjusted oxygen partial pressure, inert gases such as nitrogen, argon, and helium can be used as the gas to fill the tire.

[0115] Furthermore, in the tire of the present invention, the rubber composition of the present invention described above is used in any of the tire components, but it is preferable that it be used in the tread rubber, sidewall rubber, cord or fiber-coated rubber, bead filler, or gum chafer. This is because applying it to these components allows for the full enjoyment of the excellent low-loss effect of the rubber composition of the present invention, and consequently, the benefits of reduced rolling resistance.

[0116] While the type of tire of the present invention is not particularly limited, it is preferable that the tire be a passenger car tire, a studless tire, a run-flat tire, or a truck / bus tire, as these can more effectively achieve both improved wear resistance and reduced rolling resistance. [Examples]

[0117] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the examples described below.

[0118] (Samples 1-12) Rubber composition samples were prepared using the formulations and mixing methods shown in Table 1. The maximum temperature of the mixture during the first mixing stage is also shown in Table 1. In the preparation of the rubber composition samples, a second mixing stage is performed after the first mixing stage. Mixing is carried out using a Banbari mixer.

[0119] <Performance Evaluation> (1) Mixed viscosity For each sample rubber composition, the viscosity was measured after 0.1 minutes using an RPA2000 (Alpha Technologies) at 130°C for 1 minute, followed by a frequency of 1 Hz and 100% strain. A smaller value indicates better processability. The measurement results for each example and comparative example are shown in Table 1. A smaller measurement value indicates higher silica dispersibility and a better result.

[0120] (2) Low loss The rubber composition of each sample is vulcanized at 160°C for 15 minutes to obtain vulcanized rubber. The loss tangent (tanδ) of the obtained vulcanized rubber is measured using ARES-G2 (TA Instruments) at a temperature of 30°C, a strain of 5%, and a frequency of 15Hz. The measurement results for each example and comparative example are shown in Table 1 as a relative index, with the measurement result of Comparative Example 1 set to 100. A higher index value indicates lower heat generation.

[0121] [Table 1]

[0122] *1 The SBR-1 will be fabricated under the following conditions. In a dry, nitrogen-purged 800 ml pressure-resistant glass container, cyclohexane solutions of 1,3-butadiene and styrene are added to a total volume of 67.5 g of 1,3-butadiene and 7.5 g of styrene. 0.6 mmol of 2,2-ditetrahydrofurylpropane is added, followed by 0.8 mmol of n-butyllithium, and polymerization is carried out at 50°C for 1.5 hours. To the polymerization reaction system where the polymerization conversion rate is nearly 100%, 0.72 mmol of [N,N-bis(trimethylsilyl)-(3-amino-1-propyl)](methyl)(diethoxy)silane is added, and a denaturation reaction is carried out at 50°C for 30 minutes. Subsequently, 2 ml of a 5% by mass solution of 2,6-di-t-butyl-p-cresol (BHT) in isopropanol is added to stop the reaction, and the mixture is dried according to a conventional method to obtain modified SBR-1. Furthermore, the microstructure of the resulting modified SBR-1 was measured, revealing a bound styrene content of 10% by mass, a vinyl content of 40% in the butadiene portion, and a polystyrene-equivalent peak molecular weight of 200,000 obtained by gel permeation chromatography. *2 The SBR-2 will be manufactured under the following conditions. (Examples of denaturing agent manufacturing) Two vacuum-dried 4L stainless steel pressure vessels are prepared. 944g of cyclohexane, 161g of the compound represented by the chemical formula (2-1) below, and 86g of tetramethylethylenediamine are added to the first pressure vessel to prepare the first reaction solution. Simultaneously, 318g of liquid 20% n-butyllithium and 874g of cyclohexane are added to the second pressure vessel to prepare the second reaction solution. At this time, the molar ratio of the compound represented by the chemical formula (2-1), n-butyllithium, and tetramethylethylenediamine is 1:1:1. While maintaining the pressure in each pressure vessel at 7 bar, the first reaction solution is injected into the first continuous channel at a rate of 1.0 g / min, and the second reaction solution is injected into the second continuous channel at a rate of 1.0 g / min, using a mass flow meter. During this time, the temperature of the continuous reactor is maintained at -10°C, the internal pressure is maintained at 3 bar using a backpressure regulator, and the residence time in the reactor is adjusted to be within 10 minutes. The reaction is then terminated to obtain the denaturing initiator. [ka] (Fabrication of modified SBR-2) In the first reactor of a continuous reactor consisting of three reactors connected in series, a styrene solution prepared by dissolving 60% by weight of styrene in n-hexane is injected at a rate of 0.84 kg / h, a 1,3-butadiene solution prepared by dissolving 60% by weight of 1,3-butadiene in n-hexane is injected at a rate of 15.10 kg / h, n-hexane is injected at a rate of 47.66 kg / h, a 1,2-butadiene solution prepared by dissolving 2.0% by weight of 1,2-butadiene in n-hexane is injected at a rate of 10 g / h, a polar additive prepared by dissolving 10% by weight of 2,2-(di-2(tetrahydrofuryl)propane in n-hexane is injected at a rate of 10.0 g / h, and the modification initiator (2-1) prepared in the above production example is injected at a rate of 292.5 g / h. At this time, the temperature of the first reactor is maintained at 50°C, and when the polymerization conversion rate reaches 43%, the polymer is transferred from the first reactor to the second reactor through the transfer piping. Next, a 1,3-butadiene solution, in which 1,3-butadiene is dissolved in n-hexane at a rate of 60% by weight, is injected into the second reactor at a rate of 0.68 kg / h. At this time, the temperature of the second reactor is maintained at 65°C, and when the polymerization conversion rate reaches 95% or higher, the polymer is transferred from the second reactor to the third reactor through the transfer piping. The polymer is transferred from the second reactor to the third reactor, and a solution containing the following formula (1a) is added to the third reactor as a denaturing agent (denaturing agent: act. Li = 1:1 mol). The temperature of the third reactor is maintained at 65°C. [ka] Subsequently, a 30% by weight solution of IR1520 (BASF) is added to the polymerization solution discharged from the third reactor at a rate of 170 g / h as an antioxidant, and the mixture is stirred. The resulting polymer is then placed in steam-heated hot water and stirred to remove the solvent, thereby obtaining modified SBR-2. Furthermore, measurements of the microstructure of the resulting modified SBR-2 revealed that it contained 5% by mass of styrene and 37% vinyl in the butadiene portion. *3 The SBR-3 will be manufactured under the following conditions. In a nitrogen-purged autoclave reactor with a volume of 5 liters, 2.750 g of cyclohexane, 2.00 g of tetrahydrofuran, 160 g of styrene, 165 g of 1,3-butadiene, and 34.9 mg (0.10 mmol) of potassium dodecylbenzenesulfonate (DBS-K) are charged. After adjusting the temperature of the reactor contents to 40°C, 215 mg (3.36 mmol) of n-butyllithium is added to start polymerization. When the polymerization temperature reaches 55°C, 165 g of 1,3-butadiene is added over 20 minutes. When the polymerization conversion rate reaches 99%, 10 g of butadiene is added and polymerization is continued for another 5 minutes, after which 545 mg (2.9 mmol) of 1-trimethylsilyl-2-ethoxymethyl-1-aza-2-sila-cyclopentane is added and the reaction is carried out for 15 minutes. After the reaction, 2,6-di-tert-butyl-p-cresol is added to the polymer solution, followed by desolvation by steam stripping, and the rubber is dried using a hot roller to obtain modified SBR-3. Furthermore, measurements of the microstructure of the obtained modified SBR-3 revealed that it contained 35% by mass of styrene and 27% of vinyl in the butadiene portion. *4 The SBR-4 will be manufactured under the following conditions. In a continuous reactor consisting of three reactors connected in series, the following solutions are injected into the first reactor at a rate of 6.58 kg / h: a styrene solution prepared by dissolving 60% styrene in n-hexane; 15.10 kg / h: a 1,3-butadiene solution prepared by dissolving 60% 1,3-butadiene in n-hexane; 49.11 kg / h: n-hexane; 40 g / h: a 1,2-butadiene solution prepared by dissolving 2.0% 1,2-butadiene in n-hexane; and as polar additives, 51.0 g / h: a solution prepared by dissolving 10% 2,2-(di-2(tetrahydrofuryl)propane in n-hexane; and 59.0 g / h: an n-butyllithium solution prepared by dissolving 10% n-butyllithium in n-hexane. During this process, the temperature of the first reactor is maintained at 50°C. Next, a 1,3-butadiene solution, in which 1,3-butadiene is dissolved in n-hexane at a rate of 60% by mass, is injected into the second reactor at a rate of 0.95 kg / h. At this time, the temperature of the second reactor is maintained at 65°C. The polymer is transferred from the second reactor to the third reactor, and a solution containing the following formula (1a) is added to the third reactor as a denaturing agent (denaturing agent: act. Li = 1:1 mol). At this time, the temperature of the third reactor is maintained at 65°C. Subsequently, a 30% by mass solution of IR1520 (BASF) is added to the polymerization solution discharged from the third reactor at a rate of 167 g / h as an antioxidant, and the mixture is stirred. The resulting polymer is then placed in steam-heated hot water and stirred to remove the solvent, thereby obtaining modified SBR-4 with one end modified. Furthermore, measurements of the microstructure of the resulting modified SBR-4 revealed that it contains 37% by mass of styrene and 40% vinyl in the butadiene portion. *5 Tosoh Silica Co., Ltd. "Nip Seal AQ", BET surface area 205m² 2 / g *6 Shin-Etsu Chemical Co., Ltd. "ABC-856", bis-triethoxysilylpropyl-polysulfide *8 1,3-diphenylguanidine, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. "Noxellar D" *9 N,N'-Diethylthiourea, manufactured by Lanxess, Lenogran DETU-80 *10 N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. "Nocrac 6C" *11 Di-2-benzothiazolyl disulfide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. "Noxellar DM-P" *12 N-tert-butyl-2-benzothiazolyl sulfenamide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. "Noxellar NS-P"

[0123] The results in Table 1 show that each sample in the examples exhibits superior silica dispersibility and low loss compared to each sample in the comparative examples. [Industrial applicability]

[0124] According to the present invention, it is possible to provide a method for producing a rubber composition that improves the dispersibility of the filler and yields a rubber composition with excellent low loss properties. Furthermore, according to the present invention, it is possible to provide a rubber composition with excellent low loss properties and a tire with reduced rolling resistance.

Claims

1. A method for producing a rubber composition comprising a rubber component (A) containing at least one selected from natural rubber and synthetic diene rubber, a filler containing an inorganic filler (B), a silane coupling agent (C), and a vulcanization accelerator (D), The rubber composition is kneaded in multiple stages, In the first stage of the mixing process, the rubber component (A), part or all of the inorganic filler (B), part or all of the silane coupling agent (C), and the vulcanization accelerator (D) are mixed together. The rubber component contains a modified copolymer modified with a modifying agent containing a compound represented by formula (1), A method for producing a rubber composition, characterized in that the vulcanization accelerator (D) is at least one vulcanization accelerator selected from guanidines, sulfenamides, thiazoles, thirams, dithiocarbamates, thioureas, and xanthogenic salts. 【Chemistry 1】 (In the formula, R １ ~R ８ Each of these is an alkyl group having 1 to 20 carbon atoms; L １ and L ２ Each of these is an alkylene group having 1 to 20 carbon atoms; n is an integer between 2 and 4.

2. The copolymer modified by the modifying agent containing the compound represented by formula (1) is a copolymer having conjugated diene units and aromatic vinyl units. A method for producing the rubber composition according to claim 1, characterized in that the content of the aromatic vinyl units in the copolymer is 40% by mass or less.

3. A method for producing a rubber composition according to claim 1 or 2, characterized in that the vulcanization accelerator (D) is at least one guanidine vulcanization accelerator.

4. A method for producing a rubber composition according to claim 1 or 2, characterized in that the vulcanization accelerator (D) is at least one thiourea-based vulcanization accelerator.

5. A method for producing a rubber composition according to claim 1 or 2, characterized in that, in the first step of the kneading, all or part of the rubber component (A), the inorganic filler (B), and all or part of the silane coupling agent (C) are kneaded, and then the vulcanization accelerator (D) is added and kneaded further.

6. A method for producing a rubber composition according to claim 1 or 2, characterized in that the maximum temperature of the rubber composition in the first stage of kneading is 120 to 190°C.

7. A method for producing a rubber composition according to claim 1 or 2, characterized in that the silane coupling agent (C) is at least one compound selected from the group consisting of compounds represented by the following general formulas (I) to (IV). 【Chemistry 2】 (In the formula, R １ If there are multiple elements, they may be the same or different, and each is a linear, cyclic, or branched alkyl group having 1 to 8 carbon atoms, a linear or branched alkoxyalkyl group having 2 to 8 carbon atoms, or a hydrogen atom, R ２ If there are multiple elements, they may be the same or different, and each is a linear, cyclic, or branched alkyl group having 1 to 8 carbon atoms, R ３ If there are multiple groups, they may be the same or different, and each is a linear or branched alkylene group with 1 to 8 carbon atoms. 'a' is 2 to 6 on average, and 'p' and 'r' may be the same or different, each averaging 0 to 3. However, both 'p' and 'r' cannot be 3. 【Transformation 3】 {In the formula, R ４ is -Cl, -Br, R ９ O-, R ９ C(=O)O-, R ９ R １０ C=NO-, R ９ R １０ CNO-, R ９ R １０ N-, and -(OSiR ９ R １０ ), h(OSiR ９ R １０ R １１ ), a monovalent group selected from (R ９ , R １０ and R １１ are each a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and h is 1 to 4 as an average value.). R ５ is R ４ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R ６ is R ４ , R ５ , a hydrogen atom or -[O(R １２ O)j] ０．５ - group (R １２ is an alkylene group having 1 to 18 carbon atoms, and j is an integer of 1 to 4.). R ７ is a divalent hydrocarbon group having 1 to 18 carbon atoms, and R ８ is a monovalent hydrocarbon group having 1 to 18 carbon atoms. x, y, and z are numbers satisfying the relationships of x + y + 2z = 3, 0 ≤ x ≤ 3, 0 ≤ y ≤ 2, and 0 ≤ z ≤ 1.}{{END}} 【Chemistry 4】 {In the formula, R １３ If there are multiple elements, they may be the same or different, and each is a linear, cyclic, or branched alkyl group having 1 to 8 carbon atoms, a linear or branched alkoxyalkyl group having 2 to 8 carbon atoms, or a hydrogen atom, R １４ If there are multiple elements, they may be the same or different, and each is a linear, cyclic, or branched alkyl group having 1 to 8 carbon atoms, R １５ If there are multiple elements, they may be the same or different, and each is a linear or branched alkylene group having 1 to 8 carbon atoms. R １６ is a general formula (-S-R １７ -S-), (-R １８ -S ｍ１ -R １９ -) and (-R ２０ -S ｍ２ -R ２１ -S ｍ３ -R ２２ -) any of the divalent groups (R １７ ~R ２２ Each of the following is a divalent hydrocarbon group, a divalent aromatic group, or a divalent organic group containing a heteroatom other than sulfur and oxygen, with m1, m2, and m3 each having an average value of 1 or more and less than 4. The multiple k values ​​may be the same or different, each having an average value of 1 to 6, and s and t each having an average value of 0 to 3. However, both s and t cannot be 3. 【Transformation 5】 {In the formula, R ２３ G is a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, and the multiple Gs may be the same or different, each being an alkanediyl or alkenediyl group having 1 to 9 carbon atoms, and the multiple Zs ａ These may be the same or different, and each is a functional group capable of bonding with two silicon atoms, and [-0-] ０．５ [-0-G-] ０．５ and [-O-G-O-] ０．５ A functional group selected from among several Z ｂ These may be the same or different, and each is a functional group capable of bonding with two silicon atoms, and [-O-G-O-] ０．５ It is a functional group represented by Z, and there are multiple Z ｃ They may be the same or different, and each is -Cl, -Br, -OR ａ , R ａ C(=O)O-, R ａ R ｂ C = NO-, R ａ R ｂ N-, R ａ - and HO-G-O- (G matches the above notation) are selected functional groups, R ａ and R ｂ Each of these is a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms. m, n, u, v, and w satisfy the following conditions: 1 ≤ m ≤ 20, 0 ≤ n ≤ 20, 0 ≤ u ≤ 3, 0 ≤ v ≤ 2, 0 ≤ w ≤ 1, and (u / 2) + v + 2w = 2 or 3. If there are multiple parts A, then Z in the multiple parts A ａ ｕ Z ｂ ｖ and Z ｃ ｗ In each case, they may be the same or different, and if there are multiple parts B, Z in the multiple parts B ａ ｕ Z ｂ ｖ and Z ｃ ｗ In each case, they may be the same or different.

8. A method for producing a rubber composition according to claim 1 or 2, characterized in that the inorganic filler (B) is silica.

9. A method for producing the rubber composition according to claim 1 or 2, characterized in that the filler further contains carbon black.

10. The method for producing a rubber composition according to claim 1 or 2, characterized in that the modifying agent is one of formulas (1a) to (1e). 【Transformation 6】 【change】

11. The method for producing a rubber composition according to claim 1 or 2, characterized in that the modified copolymer is a modified copolymer further modified with a modifying agent containing a compound represented by formula (2). 【Transformation 7】 (In formula (2), R １ ~R ３ R is independently of each other: hydrogen; C1-C30 alkyl group; C2-C30 alkenyl group; C2-C30 alkynyl group; C1-C30 heteroalkyl group, C2-C30 heteroalkenyl group; C2-C30 heteroalkynyl group; C5-C30 cycloalkyl group; C6-C30 aryl group; or C3-C30 heterocyclic group. ４ R is a single bond; a substituent is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms; a substituent is a substituted or unsubstituted cycloalkylene group having 5 to 20 carbon atoms; or a substituent is a substituted or unsubstituted arylene group having 5 to 20 carbon atoms, where the substituent is a C1 to C10 alkyl group, a C5 to C10 cycloalkyl group, or a C6 to C20 aryl group, ５ is an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; a heterocyclic group having 3 to 30 carbon atoms; or an active group represented by the following chemical formula (2a) or chemical formula (2b), where n is an integer from 1 to 5, and R ５ At least one of them is an active group represented by the following chemical formula (2a) or chemical formula (2b), and when n is an integer from 2 to 5, multiple R ５ They may be identical or different from one another. 【Transformation 8】 In equation (2a), R ６ R is a C1-C20 alkylene group with a substituent substituted or unsubstituted; a C5-C20 cycloalkylene group with a substituent substituted or unsubstituted; or a C6-C20 arylene group with a substituent substituted or unsubstituted, where the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group, ７ and R ８ R is an alkylene group having 1 to 20 carbon atoms that is independently substituted or unsubstituted with an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. ９ R9 is a hydrogen atom; an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; or a heterocyclic group having 3 to 30 carbon atoms. X is an N, O, or S atom, and when X is O or S, R9 does not exist. 【Chemistry 9】 In formula (2b), R １０ is an alkylene group having 1 to 20 carbon atoms which may or may not be substituted with a substituent; a cycloalkylene group having 5 to 20 carbon atoms which may or may not be substituted with a substituent; or an arylene group having 6 to 20 carbon atoms which may or may not be substituted with a substituent, where the substituent is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms, R １１ and R １２ are, independently of each other, an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; a heterocyclic group having 3 to 30 carbon atoms.)

12. A rubber composition characterized by being obtained by the method for producing the rubber composition described in claim 1.

13. A tire characterized by using the rubber composition described in claim 12.

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