Method for producing rubber composition

Abstract

To provide a method for producing a rubber composition which suppresses short scorch and variation in hardness and can impart excellent chipping resistance.SOLUTION: There is provided a method for producing a rubber composition which comprises a rubber component containing 50 mass% or more of an isoprene-based rubber, silica, a mercapto-based silane coupling agent, a dibenzylamine compound and a thiuram-based vulcanization accelerator, which comprises: a first base kneading step of kneading the rubber component, the silica and the mercapto-based silane coupling agent; a second base kneading step of kneading a first kneaded material obtained in the first kneading step and the dibenzylamine compound; and a finishing kneading step of kneading a second kneaded material obtained in the second kneading step and the thiuram-based vulcanization accelerator.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing a rubber composition. [Background technology]

[0002] In harsh environmental conditions such as those in the Middle East, tires must be durable, primarily with respect to chipping resistance and abrasion resistance. For this reason, compounds primarily containing natural rubber are generally used, but this compounding method is contrary to the increasing demand for fuel-efficient performance in recent years. Summary of the Invention [Problem to be solved by the invention]

[0003] To address these contradictory performance issues, the use of mercapto silane coupling agents and dibenzylamine compounds (crosslinking agents), which have excellent chipping resistance, has been proposed. Dibenzylamine compounds, like sulfur, have the ability to crosslink raw rubber, but their crosslinking chains are longer than sulfur, which tends to improve chipping resistance. However, when dibenzylamine compounds are used, the sulfur length is shorter than in conventional rubber compounds, making the crosslinking reaction less likely to proceed. Therefore, the use of thiuram vulcanization accelerators, which have a high crosslinking acceleration effect, is considered.

[0004] However, the present inventors have found that adding the three components of a mercapto silane coupling agent, a dibenzylamine compound, and a thiuram vulcanization accelerator in the conventional manufacturing process creates new problems, such as short scorch and variations in hardness in the compounded rubber. Specifically, it is difficult to ensure sufficient dispersibility of dibenzylamine compounds, but it is desirable to add them at the beginning of the kneading process to increase dispersibility in order to ensure chipping resistance. However, it was discovered that if dibenzylamine compounds are added at the beginning of the kneading process, they will react with the mercapto-silane coupling agent, which is also added at the beginning of the kneading process, at temperatures above 150°C, causing short scorch. It was also found that adding a dibenzylamine compound during the finishing mixing step when adding a thiuram vulcanization accelerator results in a decrease in chipping resistance because the dibenzylamine compound has low dispersibility compared to the thiuram vulcanization accelerator, which has a high vulcanization-accelerating ability.

[0005] To address this new issue, the present inventors discovered that short scorch can be suppressed by first adding a mercapto silane coupling agent in the initial kneading step to ensure silica dispersibility, kneading at a temperature of 150 to 160°C, etc., and then discharging the mixture, and then adding a dibenzylamine compound and kneading it. Furthermore, they discovered that adding a thiuram vulcanization accelerator and kneading it in the final finishing kneading step of adding a vulcanizing agent after kneading the dibenzylamine compound can suppress the deterioration of chipping resistance and also suppress variations in hardness. Therefore, this manufacturing method can suppress short scorch and variations in hardness, and can also provide good chipping resistance.

[0006] The present disclosure aims to solve the above problems and provide a method for producing a rubber composition that can suppress short scorch and hardness variations and can impart excellent chipping resistance. [Means for solving the problem]

[0007] The present disclosure provides a method for producing a rubber composition including a rubber component containing 50% by mass or more of an isoprene-based rubber, silica, a mercapto-based silane coupling agent, a dibenzylamine compound, and a thiuram-based vulcanization accelerator, a first base kneading step of kneading the rubber component, the silica, and the mercapto-based silane coupling agent; a second base kneading step in which the first kneaded material obtained in the first base kneading step and the dibenzylamine compound are kneaded together; The present invention relates to a method for producing a rubber composition, which includes a finish kneading step of kneading the second kneaded product obtained in the second base kneading step and the thiuram vulcanization accelerator. [Effects of the Invention]

[0008] According to the present disclosure, there is provided a method for producing a rubber composition comprising a rubber component containing 50% by mass or more of isoprene-based rubber, silica, a mercapto-based silane coupling agent, a dibenzylamine compound, and a thiuram-based vulcanization accelerator, the method comprising: a first base kneading step of kneading the rubber component, the silica, and the mercapto-based silane coupling agent; a second base kneading step of kneading the first kneaded product obtained in the first base kneading step with the dibenzylamine compound; and a finish kneading step of kneading the second kneaded product obtained in the second base kneading step with the thiuram-based vulcanization accelerator. Therefore, it is possible to provide a method for producing a rubber composition that can suppress short scorch and variations in hardness and impart excellent chipping resistance. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present disclosure provides a method for producing a rubber composition containing a rubber component containing 50% by mass or more of isoprene-based rubber, silica, a mercapto-silane coupling agent, a dibenzylamine compound, and a thiuram-based vulcanization accelerator. The method includes a first base kneading step in which the rubber component, the silica, and the mercapto-silane coupling agent are kneaded together; a second base kneading step in which the first kneaded mixture obtained in the first base kneading step is kneaded together with the dibenzylamine compound; and a finish kneading step in which the second kneaded mixture obtained in the second base kneading step is kneaded together with the thiuram-based vulcanization accelerator. This production method can suppress short scorch and hardness variations. It also provides a rubber composition with excellent chipping resistance.

[0010] First, each component used in the present disclosure will be described.

[0011] (rubber component) In the present disclosure, an isoprene-based rubber is used as the rubber component.

[0012] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. NRs such as SIR20, RSS#3, and TSR20 are commonly used in the tire industry. IRs are not particularly limited, and examples of IRs such as IR2200 are commonly used in the tire industry. Modified NRs include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more. NR is preferred.

[0013] In the rubber composition obtained by the manufacturing method of the present disclosure, the content of the isoprene-based rubber in 100% by mass of the rubber component is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 75% by mass or more. There is no particular upper limit, but it is preferably 95% by mass or less, more preferably 90% by mass or less. Within the above range, the effects tend to be more favorable.

[0014] Usable rubber components other than isoprene-based rubber are not particularly limited, and those known in the tire field can be used. Examples include diene-based rubbers such as butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). These may be used alone or in combination of two or more. Among these, BR and SBR are preferred from the viewpoint of obtaining better effects.

[0015] The BR is not particularly limited, and examples thereof include BRs with a high cis content such as BR1220 manufactured by Zeon Corporation, BR150B manufactured by Ube Industries, Ltd., and BR1280 manufactured by LG Chem, BRs containing 1,2-syndiotactic polybutadiene crystals (SPB) such as VCR412 and VCR617 manufactured by Ube Industries, Ltd., and butadiene rubbers synthesized using a rare earth catalyst (rare earth BR), which are commonly used in the tire industry. These may be used alone or in combination of two or more.

[0016] The cis amount (cis content) of the BR is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more, and is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less. Within the above ranges, the effect tends to be more favorably obtained. The cis content of BR can be measured by infrared absorption spectroscopy.

[0017] When the rubber composition contains BR, the content of BR in 100% by mass of the rubber component in the rubber composition obtained by the production method of the present disclosure is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less. When the content is within the above range, better effects tend to be obtained.

[0018] The SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. Commercially available products include those from Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation.

[0019] The styrene content of SBR is preferably 10% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, and particularly preferably 35% by mass or more. The styrene content is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less. Within the above range, the effect tends to be more favorable. In this specification, the styrene content of SBR is 1 It is calculated by H-NMR measurement.

[0020] The vinyl content of the SBR is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. The vinyl content is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. Within the above range, the effect tends to be more favorable. In this specification, the vinyl content (amount of 1,2-bonded butadiene units) of SBR can be measured by infrared absorption spectroscopy.

[0021] When the rubber composition contains SBR, the content of SBR in 100% by mass of the rubber component in the rubber composition obtained by the production method of the present disclosure is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less. When the content is within the above range, better effects tend to be obtained.

[0022] The rubber component may be an oil-extended rubber. The oil used in the oil-extended rubber can be the same as the oil described below. The amount of oil in the oil-extended rubber is not particularly limited, but is usually about 10 to 50 parts by mass per 100 parts by mass of rubber solids.

[0023] The rubber component may be modified to introduce a functional group that interacts with a filler such as silica. Examples of the functional group include a silicon-containing group (-SiR3 (R may be the same or different and is hydrogen, a hydroxyl group, a hydrocarbon group, an alkoxy group, or the like), an amino group, an amido group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imido group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, or the like. These functional groups may have a substituent. Of these, a silicon-containing group is preferred, and -SiR3 (R may be the same or different and is hydrogen, a hydroxyl group, a hydrocarbon group (preferably a hydrocarbon group having 1 to 6 carbon atoms (more preferably an alkyl group having 1 to 6 carbon atoms)), or an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms)), and at least one R is a hydroxyl group) is more preferred.

[0024] Specific examples of compounds (modifiers) that introduce the above-mentioned functional groups include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane.

[0025] (filler) In the present disclosure, silica is used as the filler. Examples of silica include dry-process silica (silicic anhydride) and wet-process silica (hydrated silicic acid), with wet-process silica being preferred due to its high silanol group content. The silica raw material may be water glass (sodium silicate) or a biomass material such as rice husks. Commercially available products include those from Evonik Degussa, Tosoh Silica Co., Ltd., Solvay Japan, and Tokuyama Corporation. These may be used alone or in combination.

[0026] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 120 m 2 / g or more, more preferably 150m 2 / g or more, more preferably 160m 2 / g or more. The N2SA is preferably 200m 2 / g or less, more preferably 195m 2 / g or less, more preferably 185m 2 / g or less. The lower or upper limit of the N2SA of the silica is 175m 2 / g is also acceptable. In this specification, the N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-81.

[0027] In the rubber composition obtained by the manufacturing method of the present disclosure, the content of silica is, per 100 parts by mass of the rubber component, preferably 5 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 50 parts by mass or more, particularly preferably 60 parts by mass or more, and is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 100 parts by mass or less. When the content is within the above range, better effects tend to be obtained.

[0028] Examples of fillers that can be used other than silica include inorganic fillers other than silica and carbon black. Examples of inorganic fillers other than silica include clay, alumina, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium oxide, and titanium oxide. These may be used alone or in combination of two or more. Of these, carbon black is preferred.

[0029] The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. The raw material for carbon black may be a biomass material such as lignin or vegetable oil. Furthermore, carbon black may be produced by combustion, such as in a furnace, or by hydrothermal carbonization (HTC). Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., Columbia Carbon Co., Ltd., and the like. These may be used alone or in combination.

[0030] The nitrogen adsorption specific surface area (N2SA) of carbon black is 70m 2 / g or more is preferable, and 90m 2 / g or more is more preferable, and 100m 2 / g or more is more preferable. 2 / g or less is preferable, and 150m 2 / g or less is more preferable, and 130m 2 Within the above range, the effect tends to be better. The nitrogen adsorption specific surface area of ​​carbon black can be determined according to JIS K6217-2:2001.

[0031] In the rubber composition obtained by the production method of the present disclosure, the content of carbon black is, per 100 parts by mass of the rubber component, preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less. When the content is within the above range, better effects tend to be obtained.

[0032] In the rubber composition obtained by the production method of the present disclosure, the content of the filler (total content of silica, carbon black, etc.) per 100 parts by mass of the rubber component is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 70 parts by mass or more, and is preferably 150 parts by mass or less, more preferably 130 parts by mass or less, even more preferably 120 parts by mass or less. When the content is within the above range, better effects tend to be obtained.

[0033] (Silane coupling agent) In the present disclosure, a mercapto-based silane coupling agent is used as the silane coupling agent. The mercapto-based silane coupling agents may be used alone or in combination of two or more.

[0034] As the mercapto-based silane coupling agent, in addition to a compound having a mercapto group, a compound having a structure in which the mercapto group is protected by a protecting group (for example, a compound represented by the following formula (S1)) can also be used.

[0035] Particularly suitable mercapto-based silane coupling agents include silane coupling agents represented by the following formula (S1) and silane coupling agents containing a bonding unit A represented by the following formula (I) and a bonding unit B represented by the following formula (II). [ka] (In the formula, R 1001 -Cl, -Br, -OR 1006 , -O(O=)CR 1006 , -ON=CR 1006 R 1007 , -NR 1006 R 1007 and-(OSiR 1006 R 1007 ) h (OSiR 1006 R 1007 R 1008 a monovalent group (R 1006 , R 1007 and R 1008may be the same or different, and each represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and h has an average value of 1 to 4; 1002 is R 1001 , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R 1003 is -[O(R 1009 O) j ]-group(R 1009 is an alkylene group having 1 to 18 carbon atoms, and j is an integer of 1 to 4. 1004 is a divalent hydrocarbon group having 1 to 18 carbon atoms, R 1005 represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, and x, y, and z are numbers that satisfy the relationships: x+y+2z=3, 0≦x≦3, 0≦y≦2, 0≦z≦1. [ka] [ka] (wherein v is an integer of 0 or more, and w is an integer of 1 or more. R 11 R represents hydrogen, halogen, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched alkynyl group having 2 to 30 carbon atoms, or an alkyl group in which the terminal hydrogen atom has been substituted with a hydroxyl group or a carboxyl group. 12 represents a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, or a branched or unbranched alkynylene group having 2 to 30 carbon atoms. 11 and R 12 may form a ring structure with

[0036] In formula (S1), R 1005 , R 1006 , R 1007 and R 1008 are each independently a group selected from the group consisting of a linear, cyclic or branched alkyl group, an alkenyl group, an aryl group and an aralkyl group having 1 to 18 carbon atoms. 1002When R is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is preferably a group selected from the group consisting of a linear, cyclic, or branched alkyl group, an alkenyl group, an aryl group, and an aralkyl group. 1009 R is preferably a linear, cyclic or branched alkylene group, and is particularly preferably a linear one. 1004 Examples of R 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 either linear or branched, and the cycloalkylene groups, cycloalkylalkylene groups, arylene groups, and aralkylene groups may have a functional group such as a lower alkyl group on the ring. 1004 As the alkylene group, an alkylene group having 1 to 6 carbon atoms is preferred, and a linear alkylene group such as a methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group, or hexamethylene group is particularly preferred.

[0037] R in formula (S1) 1002 , R 1005 , R 1006 , R 1007 and R 1008 Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a cyclopentyl group, a cyclohexyl group, a vinyl group, a propenyl group, an allyl group, a hexenyl group, an octenyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a benzyl group, a phenethyl group, and a naphthylmethyl group. R in formula (S1) 1009 Examples of the linear alkylene group include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, and a hexylene group, and examples of the branched alkylene group include an isopropylene group, an isobutylene group, and a 2-methylpropylene group.

[0038] Specific examples of the silane coupling agent represented by formula (S1) 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. These may be used alone or in combination of two or more. Among these, 3-octanoylthiopropyltriethoxysilane is particularly preferred.

[0039] In the silane coupling agent containing the bond unit A represented by formula (I) and the bond unit B represented by formula (II), the content of the bond unit A is preferably 30 mol% or more, more preferably 50 mol% or more, and preferably 99 mol% or less, more preferably 90 mol% or less. The content of the bond unit B is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and preferably 70 mol% or less, more preferably 65 mol% or less, even more preferably 55 mol% or less. The total content of the bond units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, particularly preferably 100 mol%. The content of the bonding units A and B includes the case where the bonding units A and B are located at the terminals of the silane coupling agent. When the bonding units A and B are located at the terminals of the silane coupling agent, the form of the bonding units A and B is not particularly limited, as long as they form units corresponding to the formulas (I) and (II) representing the bonding units A and B.

[0040] R in formulas (I) and (II) 11 With respect to the above, examples of halogen include chlorine, bromine, and fluorine. Examples of branched or unbranched alkyl groups having 1 to 30 carbon atoms include methyl and ethyl groups. Examples of branched or unbranched alkenyl groups having 2 to 30 carbon atoms include vinyl and 1-propenyl groups. Examples of branched or unbranched alkynyl groups having 2 to 30 carbon atoms include ethynyl and propynyl groups.

[0041] R in formulas (I) and (II) 12 Regarding the above, examples of branched or unbranched alkylene groups having 1 to 30 carbon atoms include an ethylene group, a propylene group, etc. Examples of branched or unbranched alkenylene groups having 2 to 30 carbon atoms include a vinylene group, a 1-propenylene group, etc. Examples of branched or unbranched alkynylene groups having 2 to 30 carbon atoms include an ethynylene group, a propynylene group, etc.

[0042] In a silane coupling agent containing a bonding unit A represented by formula (I) and a bonding unit B represented by formula (II), the total number of repetitions (v+w) of the bonding unit A (v) and the bonding unit B (w) is preferably in the range of 3 to 300.

[0043] In the rubber composition obtained by the manufacturing method of the present disclosure, the content of the mercapto silane coupling agent is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 8 parts by mass or more, relative to 100 parts by mass of silica contained in the rubber composition, and is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. When the content is within the above range, better effects tend to be obtained.

[0044] In the present disclosure, silane coupling agents that can be further blended in addition to the mercapto-based silane coupling agent are not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, Examples of such compounds include sulfide-based compounds such as bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; vinyl-based compounds such as vinyl triethoxysilane and vinyl trimethoxysilane; amino-based compounds such as 3-aminopropyl triethoxysilane and 3-aminopropyl trimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyl triethoxysilane and γ-glycidoxypropyl trimethoxysilane; nitro-based compounds such as 3-nitropropyl trimethoxysilane and 3-nitropropyl triethoxysilane; and chloro-based compounds such as 3-chloropropyl trimethoxysilane and 3-chloropropyl triethoxysilane.

[0045] In the rubber composition obtained by the manufacturing method of the present disclosure, the total amount of silane coupling agents (total content of mercapto-based silane coupling agents and other silane coupling agents) is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 8 parts by mass or more, relative to 100 parts by mass of silica contained in the rubber composition, and is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. When it is within the above range, better effects tend to be obtained.

[0046] As the silane coupling agent, for example, products from Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Dow Corning Toray Co., Ltd., etc. can be used.

[0047] (Dibenzylamine compounds) In the present disclosure, a dibenzylamine compound is used. The dibenzylamine compound may be used alone or in combination of two or more types.

[0048] The dibenzylamine compound is a compound having at least one group (dibenzylamine group) represented by the following formula: [ka]

[0049] Specific examples of dibenzylamine compounds include dibenzylamine, tetrabenzylthiuram disulfide (TBzTD), zinc dibenzyldithiocarbamate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, etc. Commercially available products include those from Sanshin Chemical Industry Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Lanxess, etc. These may be used alone or in combination of two or more. Of these, compounds having two dibenzylamine groups are preferred, and 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane is more preferred.

[0050] In the rubber composition obtained by the manufacturing method of the present disclosure, the content of the dibenzylamine compound is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and even more preferably 1.2 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 6 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 2 parts by mass or less. When the content is within the above range, better effects tend to be obtained.

[0051] (softener) The rubber composition of the present disclosure may contain a softener. The softener may be used alone or in combination of two or more kinds.

[0052] As the softener, any softener known in the tire field that is in a liquid state at room temperature (20°C) can be used. Specific examples include oil, aromatic resin, C5 petroleum resin, C9 petroleum resin, etc. Of these, oil is preferred.

[0053] As the oil, petroleum oils and the like can be suitably used to improve the processability of rubber (softening effect, compounding ingredient dispersion effect, lubrication effect between polymer chains, etc.). Specific examples include paraffinic process oil, naphthenic process oil, and aromatic process oil, as well as alternative aromatic oils such as treated distillate aromatic extracts (TDAE) and solvent residue aromatic extracts (SRAE), and mild extraction solvates (MES).

[0054] In the rubber composition obtained by the manufacturing method of the present disclosure, the content of the softener is preferably 2 parts by mass or more, more preferably 8 parts by mass or more, per 100 parts by mass of the rubber component. Furthermore, the content is preferably 40 parts by mass or less, more preferably 30 parts by mass or less. Within the above range, the effect tends to be more favorable.

[0055] (Other base ingredients) The rubber composition of the present disclosure may contain other materials (antioxidants, waxes, zinc oxide, stearic acid, etc.).

[0056] As the antioxidant, a conventionally known amine-based antioxidant can be used, and specific examples include phenyleneamine-based antioxidants such as N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine. In the rubber composition obtained by the production method of the present disclosure, the content of the antioxidant is preferably 0.5 to 10 parts by mass per 100 parts by mass of the rubber component.

[0057] The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant wax and animal wax; and synthetic waxes such as polymers of ethylene, propylene, etc. In the rubber composition obtained by the production method of the present disclosure, the content of the wax is preferably 0.2 to 8 parts by mass per 100 parts by mass of the rubber component.

[0058] As the zinc oxide and stearic acid, conventionally known ones can be used. In the rubber composition obtained by the production method of the present disclosure, the contents of zinc oxide and stearic acid are preferably 0.5 to 8 parts by mass and 1 to 10 parts by mass, respectively, per 100 parts by mass of the rubber component.

[0059] (vulcanized materials) In the present disclosure, a thiuram vulcanization accelerator is used. The thiuram vulcanization accelerators may be used alone or in combination of two or more.

[0060] As the thiuram vulcanization accelerator that can be used in the present disclosure, for example, a vulcanization accelerator represented by the following formula (1) can be suitably used. R 1 R 2 N-(C=S)-Sz(C=S)-NR 3 R 4 (1)

[0061] In the above formula (1), z represents an integer of 1 to 8 (preferably 1 to 6, more preferably 1 to 3).

[0062] R in the above formula (1) 1 ~R 4 are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms (preferably 2 to 12, more preferably 4 to 10). 1 ~R 4 Examples of the hydrocarbon group include monovalent aliphatic hydrocarbon groups such as alkyl groups, and monovalent aromatic hydrocarbon groups such as aryl groups. Preferably, it is an alkyl group, more preferably an alkyl group having a branched structure, and even more preferably a 2-ethylhexyl group.

[0063] Examples of the vulcanization accelerator represented by the above formula (1) include Nocceler TBzTD (tetrabenzyl thiuram disulfide) and Nocceler TOT-N (tetrakis(2-ethylhexyl) thiuram disulfide), both manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Among these, tetrabenzyl thiuram disulfide is preferred from the viewpoint of obtaining better effects.

[0064] In the rubber composition obtained by the production method of the present disclosure, the content of the thiuram vulcanization accelerator per 100 parts by mass of the rubber component is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, even more preferably 0.5 part by mass or more, and is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 2 parts by mass or less.

[0065] As the vulcanizing material, it is desirable to use, for example, sulfur. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. Commercially available products include those from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more.

[0066] In the rubber composition obtained by the production method of the present disclosure, the sulfur content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 6 parts by mass or less, more preferably 4 parts by mass or less, per 100 parts by mass of the rubber component.

[0067] As vulcanization accelerators that can be further blended in addition to the thiuram vulcanization accelerator, those commonly used in the tire industry can be used, and examples thereof include guanidines, sulfenamides, thiazoles, dithiocarbamates, thioureas, and xanthogenates.

[0068] Specific examples include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenyl guanidine, di-orthotolyl guanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more.

[0069] In the rubber composition obtained by the production method of the present disclosure, the total amount of vulcanization accelerators (total content of thiuram vulcanization accelerators and other vulcanization accelerators) per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, even more preferably 6 parts by mass or less.

[0070] (Other ingredients) In addition to the above components, other compounding ingredients may be appropriately blended into the rubber composition obtained by the manufacturing method of the present disclosure.

[0071] Next, each kneading step in the manufacturing method of the present disclosure will be described.

[0072] (First base kneading process) In the first base kneading step, a rubber component, silica, and a mercapto-silane coupling agent are kneaded to obtain a first kneaded mixture. By kneading the mercapto-silane coupling agent in the first base kneading step, the dispersibility of the silica can be ensured.

[0073] The kneading method is not particularly limited, and known kneaders such as a Banbury mixer and a kneader can be used. The kneading temperature in the first base kneading step is preferably 130°C or higher, more preferably 150°C or higher, from the viewpoint of silica dispersibility, etc. The upper limit of the kneading temperature is preferably 1180°C or lower, more preferably 175°C or lower. It is particularly desirable to knead up to 150°C or higher (for example, 150 to 160°C) and then discharge the mixture. The kneading time is not particularly limited, and may be adjusted as appropriate to obtain the desired dispersibility; for example, kneading for 1 to 10 minutes is sufficient.

[0074] In the first base kneading step, a mercapto-based silane coupling agent is kneaded. From the viewpoint of suppressing short scorch, it is preferable to knead 80% by mass or more of the total amount (100% by mass) of the mercapto-based silane coupling agent used in the rubber composition obtained by the manufacturing method of the present disclosure in the first base kneading step, more preferably kneading 90% by mass or more, even more preferably kneading 95% by mass or more, and particularly preferably kneading 100% by mass (total amount).

[0075] In the first base kneading step, the mercapto silane coupling agent is preferably kneaded in an amount of 3 to 25 parts by mass, more preferably 5 to 20 parts by mass, and even more preferably 8 to 15 parts by mass, per 100 parts by mass of silica to be kneaded in the step. Within the above ranges, better effects tend to be obtained.

[0076] The entire rubber component may be kneaded in the first base kneading step, or may be kneaded separately in the first and second base kneading steps, etc., but from the viewpoint of ensuring the dispersibility of silica, it is preferable to knead the entire rubber component in the first base kneading step.

[0077] The entire amount of silica may be kneaded in the first base kneading step, or may be kneaded separately in the first and second base kneading steps, etc., but from the viewpoint of ensuring the dispersibility of the silica, it is preferable to knead 80% by mass or more of the total amount of silica (100% by mass) used in the rubber composition obtained by the manufacturing method of the present disclosure in the first base kneading step, more preferably knead 90% by mass or more, even more preferably knead 95% by mass or more, and particularly preferably knead 100% by mass (total amount).

[0078] In the first base kneading step, components other than the above components may be kneaded as appropriate.

[0079] (Second base kneading process) In the second base kneading step, the first kneaded material obtained in the first base kneading step is kneaded with a dibenzylamine compound to obtain a second kneaded material. By kneading the prepared first kneaded material with the dibenzylamine compound, it is possible to suppress short scorch, prevent a decrease in chipping resistance, and ensure the dispersibility of the dibenzylamine compound.

[0080] The kneading method is not particularly limited, and known kneaders such as a Banbury mixer and a kneader can be used. The kneading temperature in the second base kneading step is preferably 160°C or lower, more preferably 155°C or lower, and even more preferably 145°C or lower, from the viewpoint of suppressing short scorch. The lower limit of the kneading temperature is preferably 110°C or higher, more preferably 120°C or higher. It is particularly desirable to knead until the temperature reaches 145°C or lower (for example, 130 to 145°C) and then discharge the mixture. The kneading time is not particularly limited, and may be appropriately adjusted so as to obtain the desired dispersibility; for example, kneading for 1 to 10 minutes is sufficient.

[0081] In the second base kneading step, a dibenzylamine compound is kneaded. From the viewpoints of suppressing short scorch, preventing a decrease in chipping resistance, and ensuring dispersibility of the dibenzylamine compound, it is preferable to knead 80% by mass or more of the total amount (100% by mass) of the dibenzylamine compound used in the rubber composition obtained by the manufacturing method of the present disclosure in the second base kneading step, more preferably kneading 90% by mass or more, even more preferably kneading 95% by mass or more, and particularly preferably kneading 100% by mass (total amount).

[0082] In the second base kneading step, the dibenzylamine compound is preferably kneaded in an amount of 0.5 to 6 parts by mass, more preferably 0.8 to 4 parts by mass, and even more preferably 1.2 to 2 parts by mass, per 100 parts by mass of the rubber component kneaded in the step. Within the above ranges, better effects tend to be obtained.

[0083] In the second base kneading step, components other than the above components may be kneaded as appropriate.

[0084] (Other processes that can be carried out before the finishing kneading process) The manufacturing method of the present disclosure may include a step other than the first base kneading step and the second base kneading step before the final kneading step. Examples of the other step include one or more kneading steps carried out before the first base kneading step, between the first base kneading step and the second base kneading step, or after the second base kneading step. When another step is carried out between the first base kneading step and the second base kneading step, the kneaded product obtained in the other step is used as the first kneaded product in the second base kneading step. When another step is carried out after the second base kneading step, the kneaded product obtained in the other step is used as the second kneaded product in the final kneading step.

[0085] A specific example of the other step is a re-kneading step (remill) in which the second kneaded product obtained in the second base kneading step is discharged from the kneader, and then re-introduced into the kneader and re-kneaded. The kneading method can be the same as that of the second base kneading step. The kneading time in the re-kneading step is preferably 1 to 8 minutes, and the kneading temperature is preferably 130 to 160°C.

[0086] (finishing kneading process) In the final mixing step, the second mixture obtained in the second base mixing step is mixed with a thiuram vulcanization accelerator. The mixing method is not particularly limited, and a known mixer such as an open roll mixer can be used. The mixing time is preferably 0.5 to 15 minutes, and the mixing temperature is preferably 40 to 80°C.

[0087] In the final mixing step, a thiuram vulcanization accelerator is mixed in. From the viewpoint of preventing a decrease in chipping resistance, of the total amount (100% by mass) of the thiuram vulcanization accelerator used in the rubber composition obtained by the production method of the present disclosure, it is preferable to mix 80% by mass or more in the final mixing step, more preferably mix 90% by mass or more, even more preferably mix 95% by mass or more, and particularly preferably mix 100% by mass (total amount).

[0088] In the finish mixing step, the thiuram vulcanization accelerator is mixed in an amount of preferably 0.1 to 5 parts by mass, more preferably 0.3 to 3 parts by mass, and even more preferably 0.5 to 2 parts by mass, per 100 parts by mass of the rubber component mixed in the step. When the amount is within the above range, better effects tend to be obtained.

[0089] In the final kneading step, it is desirable to knead sulfur. It is preferable that the entire amount of sulfur is mixed in the final mixing step.

[0090] In the final kneading step, a vulcanization accelerator other than the thiuram vulcanization accelerator (another vulcanization accelerator) may be kneaded. In this case, out of the total amount (100% by mass) of other vulcanization accelerators used in the rubber composition obtained by the production method of the present disclosure, it is preferable to knead 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 100% by mass (total amount) in the final kneading step.

[0091] In the final mixing step, 1 to 10 parts by mass of a vulcanization accelerator (total amount of thiuram vulcanization accelerator and other vulcanization accelerators) is mixed with 100 parts by mass of the rubber component mixed in the step, preferably 2 to 8 parts by mass, more preferably 3 to 6 parts by mass. Within the above ranges, better effects tend to be obtained.

[0092] In the final kneading step, the second kneaded material, sulfur, and a vulcanization accelerator are usually kneaded together. However, if some of the materials that are usually kneaded in the base kneading step are not kneaded together in the first and second base kneading steps, those materials may also be kneaded as appropriate.

[0093] (Subsequent steps) The kneaded product (unvulcanized rubber composition) obtained in the finish kneading step is extruded to match the shapes of components such as treads and sidewalls, molded in a tire building machine by a conventional method, and laminated together with other tire components to form an unvulcanized tire, which is then heated and pressurized in a vulcanizer to produce a tire. The produced tires can be suitably used for passenger car tires, bus tires, truck tires, etc. [Example]

[0094] The present disclosure will be specifically described based on examples, but the present disclosure is not limited to these examples.

[0095] The various chemicals used in the examples and comparative examples will be collectively described below. NR:TSR20 SBR: SBR1502 (styrene content: 23.5% by mass) manufactured by Sumitomo Chemical Co., Ltd. BR:BR730 (manufactured by JSR, cis content: 95% by mass) Carbon black: Show Black N220 (N2SA: 111m) manufactured by Cabot Japan Co., Ltd. 2 / g, DBP absorption: 115ml / 100g) Silica: Ultrasil VN3 (N2SA175m) manufactured by Evonik Degussa 2 / g) Silane coupling agent: NXT-Z45 manufactured by Momentive (a copolymer of bonding unit A and bonding unit B (bonding unit A: 55 mol %, bonding unit B: 45 mol %)) Aromatic process oil: Diana Process AH-24 manufactured by Idemitsu Kosan Co., Ltd. Zinc oxide: Zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: NOF Corp.'s Tsubaki Anti-aging agent: Antigen 6C (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. Wax: Sunnock N manufactured by Ouchi Shinko Chemical Co., Ltd. Dibenzylamine compound: Vulcuren VP KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by LANXESS Sulfur: Powdered sulfur manufactured by Karuizawa Sulfur Co., Ltd. Vulcanization accelerator CZ: Noccela CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator DPG: Noccela D (N,N'-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator TBzTD: Sancerer TBzTD (tetrabenzyl thiuram disulfide) manufactured by Sanshin Chemical Industry Co., Ltd.

[0096] Examples and Comparative Examples (Base kneading process) A 1.7 L Banbury mixer was used to knead the materials listed in the base kneading section of Table 1 to obtain a kneaded product. In Table 1, X-1 and X-2 indicate that the materials were added and kneaded in that order. The discharge temperature and kneading time for each kneaded product were as follows: X-1 (first base kneading process): Discharge temperature of kneaded material 1 (listed in Table 1), kneading time 150 seconds X-2 (second base kneading process): Discharge temperature of kneaded material 2 (listed in Table 1), kneading time 120 seconds (Re-mixing process (remill)) The obtained kneaded product was put into a Banbury mixer and the step of kneading again was repeated a predetermined number of times to obtain a re-kneaded product. The conditions for each re-kneading were as follows, and the number of re-kneadings was as shown in Table 1. X-3 (re-mixing process): Mixing temperature 150°C, mixing time 90 seconds (finishing kneading process) Using an open roll, the materials listed in the finishing kneading section in Table 1 were added to the kneaded material obtained in the second base kneading step or the re-kneaded material obtained in the re-kneading step, and kneaded at 70°C for 120 seconds to obtain an unvulcanized rubber composition. (Vulcanization process) The unvulcanized rubber composition obtained in the finish kneading step was press-vulcanized in a 0.5 mm thick mold at 170° C. for 20 minutes to obtain a vulcanized rubber composition.

[0097] (Test tire) Furthermore, each of the obtained unvulcanized rubber compositions was molded into a tread shape, laminated together with other tire components, and vulcanized at 170°C for 15 minutes to produce a test tire (tire size: 195 / 65R15).

[0098] The unvulcanized rubber composition, vulcanized rubber composition, and test tire obtained were evaluated as follows. The results are shown in Table 1.

[0099] Scorch Time For unvulcanized rubber compositions, in accordance with JIS K 6300-1 "Unvulcanized rubber - Physical properties - Part 1: Determination of viscosity and scorch time using a Mooney viscometer," a Mooney viscosity tester was used to measure the time required for the viscosity to rise by 5 points from the minimum viscosity (scorch time) by rotating a small rotor at a temperature of 125°C, which had been preheated for 1 minute. A longer scorch time indicates better suppression of short scorch.

[0100] <Hardness δ> The hardness of the vulcanized rubber composition was measured in accordance with the hardness measurement method specified in JIS K 6253. The more uniform the value, the more suppressed the variation in hardness.

[0101] <Chipping resistance> The above test tires were mounted on a Japanese-made FF vehicle and driven for 8000 km, after which the chipped area per block was measured and evaluated according to the following criteria. ○: Less than 20% of the surface area is missing △: Missing area is 20% or more but less than 60% ×: Missing area is 60% or more

[0102] [Table 1]

[0103] As shown in Table 1, in the examples using the manufacturing method of the present disclosure, short scorch and variations in hardness were suppressed, and chipping resistance was also excellent.

[0104] The present disclosure (1) provides a method for producing a rubber composition including a rubber component containing 50% by mass or more of an isoprene-based rubber, silica, a mercapto-based silane coupling agent, a dibenzylamine compound, and a thiuram-based vulcanization accelerator, a first base kneading step of kneading the rubber component, the silica, and the mercapto-based silane coupling agent; a second base kneading step in which the first kneaded material obtained in the first base kneading step and the dibenzylamine compound are kneaded together; The method for producing a rubber composition includes a finish kneading step of kneading the second kneaded product obtained in the second base kneading step with the thiuram vulcanization accelerator.

[0105] The present disclosure (2) is a method for producing a rubber composition according to the present disclosure (1), wherein the mercapto-based silane coupling agent comprises at least one selected from the group consisting of silane coupling agents represented by the following formula (S1) and silane coupling agents comprising a bonding unit A represented by the following formula (I) and a bonding unit B represented by the following formula (II): [ka] (In the formula, R 1001 -Cl, -Br, -OR 1006 , -O(O=)CR 1006 , -ON=CR 1006 R 1007 , -NR 1006 R 1007 and-(OSiR 1006 R 1007 ) h (OSiR 1006 R 1007 R 1008 a monovalent group (R 1006 , R 1007 and R 1008 may be the same or different, and each represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and h has an average value of 1 to 4; 1002 is R 1001 , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R 1003 is -[O(R 1009 O) j ]-group(R 1009 is an alkylene group having 1 to 18 carbon atoms, and j is an integer of 1 to 4. 1004 is a divalent hydrocarbon group having 1 to 18 carbon atoms, R 1005 represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, and x, y, and z are numbers that satisfy the relationships: x+y+2z=3, 0≦x≦3, 0≦y≦2, 0≦z≦1. [ka] [ka] (wherein v is an integer of 0 or more, and w is an integer of 1 or more. R 11R represents hydrogen, halogen, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched alkynyl group having 2 to 30 carbon atoms, or an alkyl group in which the terminal hydrogen atom has been substituted with a hydroxyl group or a carboxyl group. 12 represents a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, or a branched or unbranched alkynylene group having 2 to 30 carbon atoms. 11 and R 12 may form a ring structure with

[0106] The present disclosure (3) is a method for producing the rubber composition according to the present disclosure (1) or (2), wherein the dibenzylamine compound contains 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane.

[0107] The present disclosure (4) is a method for producing a rubber composition according to any one of the present disclosures (1) to (3), wherein the thiuram vulcanization accelerator contains a compound represented by the following formula: R 1 R 2 N-(C=S)-Sz(C=S)-NR 3 R 4 (In the formula, z represents an integer of 1 to 8. R 1 ~R 4 are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms.

[0108] The present disclosure (5) is a method for producing a rubber composition according to any one of the present disclosures (1) to (4), wherein the first base kneading step discharges the first kneaded material at 150°C or higher, and the second base kneading step discharges the second kneaded material at 145°C or lower.

[0109] The present disclosure (6) is the method for producing a rubber composition according to any one of the present disclosures (1) to (5), wherein the entire amount of the mercapto-based silane coupling agent is kneaded in the first base kneading step.

Claims

1. A method for producing a rubber composition containing a rubber component containing 50% by mass or more of an isoprene-based rubber, silica, a mercapto-based silane coupling agent, a dibenzylamine compound, and a thiuram-based vulcanization accelerator, the method comprising: The dibenzylamine compound contains a sulfur atom, a first base kneading step of kneading the rubber component, the silica, and the mercapto-based silane coupling agent; a second base kneading step in which the first kneaded material obtained in the first base kneading step and the dibenzylamine compound are kneaded together; a finish kneading step of kneading the second kneaded product obtained in the second base kneading step and the thiuram vulcanization accelerator.

2. 2. The method for producing a rubber composition according to claim 1, wherein the mercapto-based silane coupling agent comprises at least one selected from the group consisting of silane coupling agents represented by the following formula (S1) and silane coupling agents containing a bonding unit A represented by the following formula (I) and a bonding unit B represented by the following formula (II): 【Chemistry 1】 (In the formula, R １００１ is -Cl, -Br, -OR １００６ , -O(O=)CR １００６ , -ON=CR １００６ R １００７ , -NR １００６ R １００７ and -(OSiR １００６ R １００７ ) ｈ (OSiR １００６ R １００７ R １００８ a monovalent group (R １００６ , R １００７ and R １００８ may be the same or different, and each represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and h has an average value of 1 to 4; １００２ is R １００１ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R １００３ is-[O(R １００９ O) ｊ ]-group (R １００９ is an alkylene group having 1 to 18 carbon atoms, and j is an integer of 1 to 4.), R １００４ is a divalent hydrocarbon group having 1 to 18 carbon atoms, R １００５ represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, and x, y, and z are numbers that satisfy the relationship: x + y + 2z = 3, 0≦x≦3, 0≦y≦2, 0≦z≦1. 【Chemistry 2】 【Transformation 3】 (wherein v is an integer of 0 or more, and w is an integer of 1 or more. R １１ R represents hydrogen, halogen, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched alkynyl group having 2 to 30 carbon atoms, or an alkyl group in which the terminal hydrogen atom has been substituted with a hydroxyl group or a carboxyl group. １２ represents a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, or a branched or unbranched alkynylene group having 2 to 30 carbon atoms. １１ and R １２ may form a ring structure.)

3. 3. The method for producing a rubber composition according to claim 1, wherein the dibenzylamine compound includes 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane.

4. The method for producing a rubber composition according to any one of claims 1 to 3, wherein the thiuram vulcanization accelerator contains a compound represented by the following formula: R １ R ２ N-(C=S)-Sz(C=S)-NR ３ R ４ (wherein z represents an integer of 1 to 8. R １ ~R ４ are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms.

5. The method for producing a rubber composition according to any one of claims 1 to 4, wherein the first base kneading step discharges the first kneaded material at 150°C or higher, and the second base kneading step discharges the second kneaded material at 145°C or lower.

6. The method for producing a rubber composition according to any one of claims 1 to 5, wherein the entire amount of the mercapto-based silane coupling agent is kneaded in the first base kneading step.

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