Mixture containing sulfur-containing organosilicon compound, rubber composition, and tire

Abstract

To provide a mixture of organosilicon compounds excellent in dispersibility of an inorganic filler such as silica, capable of improving abrasion resistance, rolling resistance and wet grip properties of a crosslinked cured product, and suitable for a rubber composition capable of realizing a desired low fuel consumption tire.SOLUTION: A mixture of sulfur-containing organosilicon compounds, wherein an area percentage occupied by an organic compound represented by the following formula (1) in gel permeation chromatography is 90% or more with respect to the entire mixture, and an area percentage occupied by a dimer of the organic compound represented by the following formula (1) is 3% or less with respect to the entire mixture: (In the formulae, R1 represents an alkyl group, an aryl group, an aralkyl group, or an alkenyl group, R2 represents an alkyl group, an aryl group, an aralkyl group, or an alkenyl group, x is a number of 2 to 8, m is an integer of 6 to 12, and n is an integer of 1 to 3. ) SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a mixture containing a sulfur-containing organosilicon compound, and more particularly to a mixture, rubber composition, and tire containing a sulfur-containing organosilicon compound with a high content of a main component. [Background technology]

[0002] Silica-filled tires have excellent performance in automotive applications, particularly in terms of abrasion resistance, rolling resistance, and wet grip. Improvements in these properties are closely related to improvements in tire fuel economy, and therefore have been the subject of active research in recent years.

[0003] To improve fuel economy, it is necessary to increase the silica filling rate of the rubber composition. However, rubber compositions that simply contain inorganic fillers such as silica lack sufficient filler dispersibility, resulting in problems with workability, such as high unvulcanized viscosity and the need for multi-stage kneading, as well as significant reductions in the breaking strength and abrasion resistance of the rubber. Therefore, sulfur-containing organosilicon compounds are used to improve the dispersibility of inorganic fillers in rubber and to chemically bond the inorganic fillers to the rubber matrix.

[0004] Sulfur-containing organosilicon compounds include compounds containing an alkoxysilyl group and a polysulfide group in the molecule, such as bis(3-triethoxysilylpropyl)tetrasulfide and bis(3-triethoxysilylpropyl)disulfide (Patent Documents 1 to 4). In particular, sulfur-containing organosilicon compounds in which an alkoxysilyl group and a polysulfide group are linked by a long-chain alkylene group are known to improve the fuel economy and wear resistance of silica-filled tires (Patent Documents 5 to 7). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2004-525230 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-18511 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-145890 [Patent Document 4] U.S. Patent No. 6,229,036 [Patent Document 5] Japanese Patent Application Publication No. 2018-65954 [Patent Document 6] Japanese Patent Application Publication No. 2018-123260 [Patent Document 7] Japanese Patent Application Publication No. 2020-100847 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the past, when producing these sulfur-containing organosilicon compounds, it was impossible to avoid the presence of multimers such as dimers formed by reaction between sulfur-containing organosilicon compounds, and there was room for improvement in improving the fuel efficiency and other properties of silica-filled tires.

[0007] The present invention has been made in view of the above circumstances, and has as its object the provision of a mixture of organosilicon compounds suitable for use in rubber compositions which have excellent dispersibility of inorganic fillers such as silica, and which can improve the abrasion resistance, rolling resistance, and wet grip properties of the crosslinked and cured product, thereby enabling the realization of desired fuel-efficient tires. [Means for solving the problem]

[0008] As a result of extensive research into achieving the above-mentioned object, the present inventors have discovered that by adding to a rubber composition a mixture of sulfur-containing organosilicon compounds in which the dimer content is reduced to within a specific range and in which alkoxysilyl groups and polysulfide groups are linked by long-chain alkylene groups, the rubber composition can be made to have excellent dispersibility of inorganic fillers such as silica, and that the rubber composition can give a cured product that is excellent in abrasion resistance, low rolling resistance, and wet grip properties, thereby realizing the desired fuel-efficient tire characteristics, and have completed the present invention.

[0009] That is, the present invention provides: 1. A mixture of sulfur-containing organosilicon compounds, A mixture of sulfur-containing organosilicon compounds, in which the area percentage of the organic compound represented by the following formula (1) is 90% or more relative to the entire mixture, and the area percentage of the dimer of the organic compound represented by the following formula (1) is 3% or less relative to the entire mixture, as determined by gel permeation chromatography: [ka] (In the formula, R 1 each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms; R 2 each independently represents an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, x is a number from 2 to 8, m is an integer from 6 to 12, and n is an integer from 1 to 3. 2. The mixture of sulfur-containing organosilicon compounds according to 1, wherein the area percentage of the organic compound represented by formula (1) is 94% or more of the entire mixture in gel permeation chromatography. 3. A rubber composition containing the mixture of sulfur-containing organosilicon compounds according to 1 or 2. 4. The rubber composition according to 3, comprising a diene rubber and a filler. 5. A tire formed from the rubber composition according to 3 or 4. 6. A cured product of the rubber composition according to any one of 3 to 5. 7. A tire using the cured product according to 6. 8. An organosilicon compound represented by the following formula (2) and NaSH, Na2S and Na2S y (wherein y is a number from 2 to 8) and one or more aqueous solutions or dispersions selected from the group consisting of sulfur-containing metal compounds represented by the formula (1) and hydrates thereof, in the presence of a phase transfer catalyst. [ka] (In the formula, R 1 , R 2 , m and n have the same meanings as above. 9. A method for producing a mixture of sulfur-containing organosilicon compounds according to claim 8, which comprises reacting an organosilicon compound represented by formula (2) with an aqueous solution or dispersion of at least one selected from the sulfur-containing metal compounds and hydrates thereof, and sulfur in the presence of a phase transfer catalyst. to provide. [Effects of the Invention]

[0010] Rubber compositions containing the mixture of sulfur-containing organosilicon compounds of the present invention have excellent dispersibility of inorganic fillers such as silica, and tires formed from such compositions have excellent abrasion resistance, low rolling resistance, and wet grip properties, thereby satisfying the desired fuel-efficient tire characteristics. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be specifically described below. [1] Mixture of sulfur-containing organosilicon compounds The mixture of sulfur-containing organosilicon compounds of the present invention contains a sulfur-containing organosilicon compound represented by the following formula (1).

[0012] [ka]

[0013] In formula (1), R 1 each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms. R 1The alkyl group having 1 to 20 carbon atoms may be linear, branched, or cyclic, and preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 1 to 6 carbon atoms. Specific examples thereof include methyl, ethyl, n-propyl, n-butyl, n-hexyl, n-octyl, n-decyl, and n-octadecyl groups. The aryl group having 6 to 10 carbon atoms is preferably an aryl group having 6 to 8 carbon atoms, and specific examples thereof include phenyl and tolyl groups. The aralkyl group having 7 to 10 carbon atoms is preferably an aralkyl group having 7 or 8 carbon atoms, and specific examples thereof include benzyl and phenethyl groups. The alkenyl group having 2 to 10 carbon atoms preferably has 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, and specific examples thereof include vinyl, propenyl, and pentenyl groups. Among these, R 1 is preferably a hydrogen atom, a methyl group, or an ethyl group, more preferably an ethyl group.

[0014] R 2 each independently represents an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms. Specific examples of these alkyl groups, aryl groups, aralkyl groups, and alkenyl groups include R 1 Examples of the groups include the same as those exemplified in the above. Among these, R 2 As the alkyl group, a methyl group is preferred.

[0015] x represents the average number of sulfur atoms and is a number from 2 to 8, preferably a number from 2 to 4. If x is less than 2, the reactivity of the inorganic filler such as silica with the rubber is poor, resulting in poor properties of the formed tire.

[0016] m is an integer of 6 to 12, preferably an integer of 6 to 10, and more preferably 8.

[0017] n is an integer of 1 to 3, preferably 2 or 3, and more preferably 3.

[0018] Specific examples of the sulfur-containing organosilicon compound represented by the above formula (1) are not particularly limited, but include the compounds shown below: In the following formula, Me represents a methyl group, and Et represents an ethyl group (the same applies hereinafter). (EtO)3Si-C6H 12 -S2-C6H 12 -Si(OEt)3 (EtO)2MeSi-CH 12 -S2-C6H 12 -SiMe(OEt)2 (EtO)3Si-C6H 12 -S4-C6H 12 -Si(OEt)3 (EtO)2MeSi-CH 12 -S4-C6H 12 -SiMe(OEt)2 (EtO)3Si-C7H 14 -S2-C7H 14 -Si(OEt)3 (EtO)2MeSi-C7H 14 -S2-C7H 14 -SiMe(OEt)2 (EtO)3Si-C7H 14 -S4-C7H 14 -Si(OEt)3 (EtO)2MeSi-C7H 14 -S4-C7H 14 -SiMe(OEt)2 (EtO)3Si-C8H 16 -S2-C8H 16 -Si(OEt)3 (EtO)2MeSi-C8H 16 -S2-C8H 16 -SiMe(OEt)2 (EtO)3Si-C8H 16 -S4-C8H 16 -Si(OEt)3 (EtO)2MeSi-C8H 16 -S4-C8H 16 -SiMe(OEt)2 (EtO)3Si-C9H 18 -S2-C9H18 -Si(OEt)3 (EtO)2MeSi-C9H 18 -S2-C9H 18 -SiMe(OEt)2 (EtO)3Si-C9H 18 -S4-C9H 18 -Si(OEt)3 (EtO)2MeSi-C9H 18 -S4-C9H 18 -SiMe(OEt)2 (EtO)3Si-C 10 H 20 -S2-C 10 H 20 -Si(OEt)3 (EtO)2MeSi-C 10 H 20 -S2-C 10 H 20 -SiMe(OEt)2 (EtO)3Si-C 10 H 20 -S4-C 10 H 20 -Si(OEt)3 (EtO)2MeSi-C 10 H 20 -S4-C 10 H 20 -SiMe(OEt)2 (EtO)3Si-C 11 H 22 -S2-C 11 H 22 -Si(OEt)3 (EtO)2MeSi-C 11 H 22 -S2-C 11 H 22 -SiMe(OEt)2 (EtO)3Si-C 11 H 22 -S4-C 11 H 22 -Si(OEt)3 (EtO)2MeSi-C 11 H 22 -S4-C 11 H 22 -SiMe(OEt)2 (EtO)3Si-C12 H 24 -S2-C 12 H 24 -Si(OEt)3 (EtO)2MeSi-C 12 H 24 -S2-C 12 H 24 -SiMe(OEt)2 (EtO)3Si-C 12 H 24 -S4-C 12 H 24 -Si(OEt)3 (EtO)2MeSi-C 12 H 24 -S4-C 12 H 24 -SiMe(OEt)2

[0019] In the mixture of sulfur-containing organosilicon compounds of the present invention, the area percentage of the organic compound represented by formula (1) above is 90% or more, preferably 92% or more, more preferably 94% or more, of the entire mixture as measured by gel permeation chromatography, and the area percentage of the dimer of the organic compound represented by formula (1) above is 3% or less of the entire mixture. If the organic compound represented by the formula (1) and the dimer of the organic compound represented by the formula (1) are outside the above range, the rolling resistance and wet grip performance of the formed tire will be reduced.

[0020] The mixture of sulfur-containing organosilicon compounds of the present invention comprises an organosilicon compound represented by the following formula (2), NaSH, NaS, NaS y (wherein y is a number of 2 to 8, preferably 2 to 4), and their hydrates, by reacting an aqueous solution or dispersion thereof with sulfur, if necessary, in the presence of a phase transfer catalyst.

[0021] [ka] (In the formula, R 1 , R 2, m and n have the same meanings as above.

[0022] Specific examples of the organosilicon compound represented by the above formula (2) are not particularly limited, but include the compounds shown below. (EtO)3Si-C6H 12 -Cl (EtO)2MeSi-CH 12 -Cl (EtO)3Si-C7H 14 -Cl (EtO)2MeSi-C7H 14 -Cl (EtO)3Si-C8H 16 -Cl (EtO)2MeSi-C8H 16 -Cl (EtO)3Si-C9H 18 -Cl (EtO)2MeSi-C9H 18 -Cl (EtO)3Si-C 10 H 20 -Cl (EtO)2MeSi-C 10 H 20 -Cl (EtO)3Si-C 11 H 22 -Cl (EtO)2MeSi-C 11 H 22 -Cl (EtO)3Si-C 12 H 24 -Cl (EtO)2MeSi-C 12 H 24 -Cl

[0023] The amount of water in the aqueous solution or dispersion of the sulfur-containing metal compound and / or its hydrate is optional, but the total amount of water added is preferably 10 to 200 parts by mass, more preferably 30 to 100 parts by mass, per 100 parts by mass of the organosilicon compound represented by formula (2) above.

[0024] When sulfur is used in the production method of the present invention, sulfur may be added to an aqueous solution or aqueous dispersion of the sulfur-containing metal compound and / or its hydrate, or the sulfur-containing metal compound and / or its hydrate and sulfur may be simultaneously mixed with water.

[0025] The molar ratio of the organosilicon compound represented by formula (2) to the sulfur-containing metal compound and / or its hydrate, or the molar ratio of the organosilicon compound to the sulfur-containing metal compound and / or its hydrate and sulfur, can be adjusted to suit the desired average number x of sulfur atoms in formula (1). For example, when using a sulfur-containing metal compound, its hydrate, and sulfur, sulfur can be added in an amount such that the total amount of sulfur atoms is 2 to 8 moles, preferably 2 to 4 moles, per 2 moles of the organosilicon compound represented by formula (2).

[0026] The phase transfer catalyst used in the production method of the present invention is not particularly limited, but examples thereof include quaternary ammonium cation compounds, quaternary phosphonium cation compounds, crown ether compounds, and the like. The quaternary ammonium cation compound is not particularly limited, but examples thereof include tetrabutylammonium bromide, tetrabutylammonium chloride, tetramethylammonium bromide, tetramethylammonium chloride, tetraethylammonium bromide, tetraethylammonium chloride, tetrabutylammonium phosphate, tetrabutylammonium phosphite, tetrabutylammonium sulfate, tetrabutylammonium fluoride, benzyltrimethylammonium bromide, and tetraphenylammonium bromide, and preferably tetra-n-butylammonium bromide and tetra-n-butylammonium chloride. Examples of the quaternary phosphonium cation compound include tetra-n-butylphosphonium chloride, tetra-n-butylphosphonium bromide, tetraphenylphosphonium bromide, tetraphenylphosphonium chloride, triphenylmethylphosphonium bromide, and triphenylmethylphosphonium chloride, with tetra-n-butylphosphonium bromide being preferred.

[0027] The amount of phase transfer catalyst added is optional, but is preferably 0.1 to 10.0 parts by mass, more preferably 0.5 to 5.0 parts by mass, per 100 parts by mass of the organosilicon compound represented by the above formula (2).

[0028] In the above reaction, an organic solvent may be used as needed. Specific examples of the organic solvent include aliphatic hydrocarbons such as pentane, hexane, heptane, and octane, and aromatic hydrocarbons such as benzene, toluene, and xylene.

[0029] The reaction conditions in the production method of the present invention are usually 20 to 100°C, preferably 60 to 85°C, and usually 30 minutes to 20 hours, preferably 0.5 to 10 hours.

[0030] In the production method of the present invention, after the reaction is completed, the target product is separated into a layer of the target product and an aqueous layer, and the target product can be separated. If a salt precipitates, water may be added to dissolve the salt, or filtration may be performed before and / or after the separation. When a solvent is used, it may be removed by distillation under reduced pressure after separation.

[0031] [2] Rubber composition The rubber composition of the present invention contains the above-mentioned mixture of sulfur-containing organosilicon compounds of the present invention, and preferably contains (A) the mixture of sulfur-containing organosilicon compounds, (B) a diene rubber, and (C) a filler.

[0032] (A) A mixture of sulfur-containing organosilicon compounds Component (A) is a mixture of the above-mentioned sulfur-containing organosilicon compounds. Taking into consideration the physical properties of the resulting rubber and the balance between the degree of effect exerted and economic efficiency, the amount of component (A) blended is preferably 0.1 to 30 parts by mass, more preferably 2 to 20 parts by mass, per 100 parts by mass of the filler of component (C), which will be described later.

[0033] (B) Diene rubber The diene rubber of component (B) can be any rubber commonly used in various rubber compositions, and specific examples include natural rubber (NR), various isoprene rubbers (IR), various styrene-butadiene copolymer rubbers (SBR), various polybutadiene rubbers (BR), acrylonitrile-butadiene copolymer rubber (NBR), and other diene rubbers, which may be used alone or in combination of two or more.In addition to diene rubbers, non-diene rubbers such as butyl rubber (IIR) and ethylene-propylene copolymer rubbers (EPR, EPDM) can also be used in combination.

[0034] (C) Filler Examples of the filler of component (C) include those commonly used in the tire industry, such as silica, carbon black, aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, talc, and clay. These may be used alone or in combination of two or more. Among these, the rubber composition of the present invention preferably contains silica and carbon black.

[0035] Examples of carbon black include those commonly used in the tire industry, such as GPF, FEF, HAF, ISAF, and SAF. Examples of silica include silica prepared by a dry method (anhydrous silica) and silica prepared by a wet method (hydrated silica), which are commonly used in the tire industry. Among these, silica prepared by a wet method is preferred because it contains a large number of silanol groups. In particular, silica has a nitrogen adsorption specific surface area (N2SA) of 70m 2 / g or more is preferable, and 100m 2 The upper limit of N2SA is not particularly limited, but from the viewpoint of ease of handling, it is preferably 500 m 2 / g or less is preferable, and 400m 2 / g or less is more preferable.

[0036] The amount of component (C) in the rubber composition of the present invention is preferably 5 to 200 parts by mass, more preferably 30 to 120 parts by mass, per 100 parts by mass of component (B) from the viewpoints of dispersibility, fuel economy, molding processability, etc.

[0037] (D) Silane coupling agent In addition to the above components, the rubber composition of the present invention can contain (D) a silane coupling agent having an alkoxysilyl group and one or more selected from a polysulfide group, a thioester group, and a mercapto group. Component (D) is not particularly limited as long as it is a compound having such a functional group, and any conventionally known silane coupling agent compounded in rubber compositions for applications such as tires can be used.

[0038] Specific examples of the silane coupling agent include polysulfide-based organosilicon compounds such as bis-(3-bistriethoxysilylpropyl)-tetrasulfide and bis-(3-bistriethoxysilylpropyl)-disulfide; mercapto-based organosilicon compounds such as 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane; and thioester-based organosilicon compounds such as 3-octanoylthiopropyltriethoxysilane and 3-propionylthiopropyltrimethoxysilane. Also usable are reaction products of the above-mentioned sulfur-containing organosilicon compounds with alcohols containing polyether groups, hydrolysis condensates of these organosilicon compounds, and co-hydrolysis condensates of these organosilicon compounds with other organosilicon compounds having alkoxysilyl groups. The component (D) may be used alone or in combination of two or more types.

[0039] In addition to the above components (A) to (C) and, if necessary, component (D), the rubber composition of the present invention may contain various additives that are generally compounded in tires and other rubbers, such as sulfur, crosslinking agents, vulcanization accelerators, crosslinking accelerators, various oils, antioxidants, plasticizers, various resins, wax, zinc oxide, etc. The amounts of these additives may be conventional amounts as long as they do not deviate from the object of the present invention.

[0040] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur, which are commonly used in the rubber industry. These may be used alone or in combination of two or more. These sulfurs may be available from, for example, 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.

[0041] When sulfur is added, the amount added is preferably 0.1 to 5.0 parts by mass, more preferably 0.3 to 3.0 parts by mass, and even more preferably 0.5 to 2.5 parts by mass, per 100 parts by mass of component (C). Within this range, a good balance between tensile properties and abrasion resistance is achieved.

[0042] [3] Rubber products (tires) The rubber composition of the present invention can be used for producing rubber products such as tires by preparing a composition from the above-mentioned components (A) to (C) and other components by a general method and vulcanizing or crosslinking the composition. In particular, when producing tires, it is preferable that the rubber composition of the present invention be used in the tread.

[0043] A tire obtained using the rubber composition of the present invention has reduced rolling resistance and improved wet grip performance, and therefore can achieve the desired low fuel consumption. The tire structure may be a conventionally known structure, and the manufacturing method may be a conventionally known manufacturing method. In the case of a gas-filled tire, the gas to be filled in the tire may be air, air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium. [Example]

[0044] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The content of the sulfur-containing organosilicon compound in the mixture is an area % value measured by gel permeation chromatography (GPC) under the following conditions. [GPC] Apparatus: HLC-8220GPC (Tosoh Corporation) Detector: RI Column: TSKgel GMHXL-L (manufactured by Tosoh Corporation) TSKgel SuperH4000 (manufactured by Tosoh Corporation) TSKgel SuperH2000 (manufactured by Tosoh Corporation) Solvent: tetrahydrofuran Flow rate: 0.6mL / min Standard: Polystyrene

[0045] [1] Production of a mixture of sulfur-containing organosilicon compounds [Example 1-1] A 2-L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer was charged with 40.0 g (1.0 mol) of sodium hydroxide (Tokyo Chemical Industry Co., Ltd.) and 224 g (1.0 mol) of an aqueous NaSH solution (Nagao Co., Ltd., 25% by mass concentration) and stirred at 80°C for 1 hour. Subsequently, 96.3 g (3.0 mol) of sulfur (Tokyo Chemical Industry Co., Ltd.) and 195 g of water were added and stirred at 80°C for 1 hour. Subsequently, 4.3 g of tetra-n-butylammonium bromide (Tokyo Chemical Industry Co., Ltd.) was added, and 622 g (2.0 mol) of (8-chlorooctyl)triethoxysilane (Shin-Etsu Chemical Co., Ltd.) was added dropwise at 80°C over 3 hours. After the dropwise addition, the mixture was stirred for 5 hours, and the aqueous layer was removed by liquid separation at 25°C. The mixture was then concentrated under reduced pressure at 80°C and then filtered to obtain 670 g of a brown, transparent liquid. 16 -S4-C8H 16 The content of the compound represented by -Si(OC2H5)3 was 94%, and the content of its dimer was 3%.

[0046] [Example 1-2] A 2-L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer was charged with 130 g (1.0 mol) of Na2S hydrate (manufactured by Nagao Co., Ltd., concentration 60% by mass), 318 g of water, and 96.3 g (3.0 mol) of sulfur (manufactured by Tokyo Chemical Industry Co., Ltd.) and stirred at 80°C for 1 hour. Then, 4.3 g of tetra-n-butylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and 622 g (2.0 mol) of (8-chlorooctyl)triethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise at 80°C over 3 hours. After the dropwise addition, the mixture was stirred for 5 hours, and the aqueous layer was removed by liquid separation at 25°C. The mixture was then concentrated under reduced pressure at 80°C and subsequently filtered to obtain 670 g of a brown, transparent liquid. Of the resulting mixture of sulfur-containing organosilicon compounds, (C2H5O)3Si-C8H 16 -S4-C8H 16 The content of the compound represented by -Si(OC2H5)3 was 95%, and the content of its dimer was 2%.

[0047] [Examples 1-3] A 2-L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer was charged with 581 g (1.0 mol) of an aqueous solution of Na2S4 (manufactured by Nagao Co., Ltd., concentration 30% by mass) and heated to 80°C. Then, 4.3 g of tetra-n-butylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) was charged, and 622 g (2.0 mol) of (8-chlorooctyl)triethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise at 80°C over 3 hours. After the dropwise addition, the mixture was stirred for 5 hours, and the aqueous layer was removed by liquid separation at 25°C. The mixture was then concentrated under reduced pressure at 80°C and subsequently filtered to obtain 670 g of a brown, transparent liquid. Of the resulting mixture of sulfur-containing organosilicon compounds, (C2H5O)3Si-C8H 16 -S4-C8H 16 The content of the compound represented by -Si(OC2H5)3 was 95%, and the content of its dimer was 2%.

[0048] [Examples 1-4] A 2-L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer was charged with 130 g (1.0 mol) of NaS hydrate (manufactured by Nagao Co., Ltd., concentration 60% by mass), 318 g of water, and 96.3 g (3.0 mol) of sulfur (manufactured by Tokyo Chemical Industry Co., Ltd.) and stirred at 80°C for 1 hour. Subsequently, 4.3 g of tetra-n-butylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) and 21.3 g of sodium carbonate (manufactured by Tokyo Chemical Industry Co., Ltd.) were charged, and 622 g (2.0 mol) of (8-chlorooctyl)triethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise at 80°C over 3 hours. After completion of the dropwise addition, the mixture was stirred for 3 hours, and the aqueous layer was removed by liquid separation at 25°C. The mixture was then concentrated under reduced pressure at 80°C and subsequently filtered to obtain 670 g of a brown, transparent liquid. Of the resulting mixture of sulfur-containing organosilicon compounds, (C2H5O)3Si-C8H 16 -S4-C8H 16 The content of the compound represented by -Si(OC2H5)3 was 95%, and the content of its dimer was 2%.

[0049] [Examples 1-5] A 2-L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer was charged with 130 g (1.0 mol) of Na2S hydrate (manufactured by Nagao Co., Ltd., concentration 60% by mass), 318 g of water, and 96.3 g (3.0 mol) of sulfur (manufactured by Tokyo Chemical Industry Co., Ltd.) and stirred at 80°C for 1 hour. Then, 4.3 g of tetrabutylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and 622 g (2.0 mol) of (8-chlorooctyl)triethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise at 80°C over 3 hours. After the dropwise addition, the mixture was stirred for 5 hours, and the aqueous layer was removed by liquid separation at 25°C. The mixture was then concentrated under reduced pressure at 80°C and subsequently filtered to obtain 670 g of a brown, transparent liquid. Of the resulting mixture of sulfur-containing organosilicon compounds, (C2H5O)3Si-C8H 16 -S4-C8H 16 The content of the compound represented by -Si(OC2H5)3 was 96%, and the content of its dimer was 2%.

[0050] [Examples 1-6] A 2-L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer was charged with 130 g (1.0 mol) of Na2S hydrate (manufactured by Nagao Co., Ltd., concentration 60% by mass), 318 g of water, and 48.2 g (1.5 mol) of sulfur (manufactured by Tokyo Chemical Industry Co., Ltd.) and stirred at 80°C for 1 hour. Then, 4.3 g of tetra-n-butylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and 622 g (2.0 mol) of (8-chlorooctyl)triethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise at 80°C over 3 hours. After the dropwise addition, the mixture was stirred for 5 hours, and the aqueous layer was removed by liquid separation at 25°C. The mixture was then concentrated under reduced pressure at 80°C and subsequently filtered to obtain 620 g of a brown, transparent liquid. Of the resulting mixture of sulfur-containing organosilicon compounds, (C2H5O)3Si-C8H 16 -S 2.5 -C8H 16 The content of the compound represented by -Si(OC2H5)3 was 95%, and the content of its dimer was 2%.

[0051] [Comparative Example 1-1] A 2L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer was charged with 78.0g (1.0 mol) of anhydrous sodium sulfide (Nagao Co., Ltd.), 96.3g (3.0 mol) of sulfur (Tokyo Chemical Industry Co., Ltd.), and 500g of ethanol, and the mixture was stirred at 80°C for 1 hour. 622g (2.0 mol) of (8-chlorooctyl)triethoxysilane (Shin-Etsu Chemical Co., Ltd.) was added and the mixture was stirred at 80°C for 10 hours. The reaction solution was pressure filtered through a filter plate to remove the by-product salt. The mixture was then concentrated under reduced pressure at 80°C, followed by filtration to obtain 620g of a brown, transparent liquid. Of the resulting mixture of sulfur-containing organosilicon compounds, (C2H5O)3Si-C8H 16 -S4-C8H 16 The content of the compound represented by -Si(OC2H5)3 was 90%, and the content of its dimer was 7%.

[0052] [Comparative Example 1-2] A 2L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer was charged with 78.0g (1.0 mol) of anhydrous sodium sulfide (Nagao Co., Ltd.), 48.2g (1.5 mol) of sulfur (Tokyo Chemical Industry Co., Ltd.), and 500g of ethanol, and the mixture was stirred at 80°C for 1 hour. 622g (2.0 mol) of (8-chlorooctyl)triethoxysilane (Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was heated and stirred at 80°C for 10 hours. The reaction solution was pressure-filtered using a filter plate to remove by-product salts. The mixture was then concentrated under reduced pressure at 80°C, followed by filtration to obtain 580g of a brown, transparent liquid. Of the resulting mixture of sulfur-containing organosilicon compounds, (C2H5O)3Si-C8H 16 -S 2.5 -C8H 16 The content of the compound represented by -Si(OC2H5)3 was 90%, and the content of its dimer was 7%.

[0053] [2] Preparation of rubber composition [Examples 2-1 to 2-5, Comparative Example 2-1] The SBR and BR shown in Table 1 were mixed for 30 seconds using a 4 L internal mixer (MIXTRON, manufactured by Kobe Steel, Ltd.). Next, the oil, carbon black, silica, the mixture of sulfur-containing organosilicon compounds obtained in Examples 1-1 to 1-5 and Comparative Example 1-1, stearic acid, antioxidant, and wax listed in Table 1 were added, the internal temperature was raised to 150°C, and the mixture was held at 150°C for 2 minutes before being discharged. It was then stretched using rolls. The resulting rubber was again kneaded using an internal mixer (MIXTRON, manufactured by Kobe Steel, Ltd.) until the internal temperature reached 140°C, discharged, and then stretched using rolls. To this was added zinc oxide, a vulcanization accelerator, and sulfur as shown in Table 1, and the mixture was kneaded to obtain a rubber composition.

[0054] SBR: SLR-4602 (manufactured by Trinseo) BR: BR-01 (JSR Corporation) Oil: AC-12 (Idemitsu Kosan Co., Ltd.) Carbon black: Seast 3 (manufactured by Tokai Carbon Co., Ltd.) Silica: Nipsil AQ (manufactured by Tosoh Silica Corporation) Stearic acid: Industrial stearic acid (Kao Corporation) Antioxidant: Nocrac 6C (Ouchi Shinko Chemical Industry Co., Ltd.) Wax: Ozoace 0355 (manufactured by Nippon Seiro Co., Ltd.) Zinc oxide: Zinc oxide No. 3 (manufactured by Mitsui Mining & Smelting Co., Ltd.) Vulcanization accelerator (a): Noccela D (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) Vulcanization accelerator (b): Noccela DM-P (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) Vulcanization accelerator (c): Noccela CZ-G (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) Sulfur: 5% oil-treated sulfur (Hosoi Chemical Industry Co., Ltd.)

[0055] The unvulcanized and vulcanized physical properties of the rubber compositions obtained in Examples 2-1 to 2-5 and Comparative Example 2-1 were measured by the following methods. The results are also shown in Table 1. Regarding the vulcanized physical properties, the obtained rubber compositions were press-molded (160°C, 10 to 40 minutes) to produce vulcanized rubber sheets (thickness 2 mm).

[0056] [Unvulcanized physical properties] (1) Mooney viscosity Measurement was performed in accordance with JIS K 6300-1:2013, with preheating for 1 minute, measurement for 4 minutes, and at a temperature of 130°C, and expressed as an index with Comparative Example 2-1 set to 100. The smaller the index value, the lower the Mooney viscosity and the better the processability. [Vulcanization properties] (2)Hardness Durometer (Type A) hardness was measured in accordance with JIS K 6253-3:2012 and expressed as an index with Comparative Example 2-1 being 100. The larger the index value, the higher and more excellent the hardness. (3) Tensile properties JIS No. 3 dumbbell-shaped test pieces were punched out and subjected to a tensile test at a tensile speed of 500 mm / min in accordance with JIS K6251. The 50% modulus (M 50 ) [MPa], 300% modulus (M 300 ) [MPa] was measured at 25° C. The results were expressed as an index, with Comparative Example 2-1 being set at 100. A larger index value indicates a higher modulus and more excellent tensile properties. (4) Dynamic viscoelasticity (strain dispersion) Using a viscoelasticity measuring device (Metrabib), the storage modulus E' (0.5%) at 0.5% strain and the storage modulus E' (3.0%) at 3.0% strain were measured at 25°C and 55Hz, and the value of [E' (0.5%) - E' (3.0%)] was calculated. The test specimen was a sheet with a thickness of 0.2 cm and a width of 0.5 cm, with a clamp distance of 2 cm and an initial load of 1 N. The value of [E'(0.5%)-E'(3.0%)] is expressed as an index with Comparative Example 2-1 being 100, and the smaller the index value, the better the dispersibility of silica. (5) Dynamic viscoelasticity (temperature dispersion) Measurements were made using a viscoelasticity measuring device (Metrabib) under conditions of a tensile dynamic strain of 1% and a frequency of 55 Hz. The test specimen was a sheet of 0.2 cm thick and 0.5 cm wide, with a clamp distance of 2 cm and an initial load of 1 N. The values ​​of tan δ(0°C) and tan δ(60°C) are expressed as indexes, with Comparative Example 2-1 being 100. A larger index value for the tan δ(0°C) value indicates better wet grip performance. A smaller index value for the tan δ(60°C) value indicates better rolling resistance. (6) Abrasion resistance Using an FPS testing machine (manufactured by Ueshima Seisakusho), the test was carried out under the following conditions: sample speed 200 m / min, load 20 N, road surface temperature 30°C, and slip ratio 5%. The results obtained were expressed as an index, with Comparative Example 2-1 being set at 100. A larger index value indicates a smaller amount of wear and better wear resistance.

[0057] [Table 1]

[0058] As shown in Table 1, the vulcanizates of the rubber compositions obtained in Examples 2-1 to 2-5 have better silica dispersibility than the vulcanizate of the rubber composition of Comparative Example 2-1, and have improved low rolling resistance and wet grip performance while maintaining wear resistance.

Claims

1. A mixture of sulfur-containing organosilicon compounds, A mixture of sulfur-containing organosilicon compounds, in which the area percentage of the organic compound represented by the following formula (1) is 90% or more relative to the entire mixture in gel permeation chromatography, and the area percentage of the dimer of the organic compound represented by the following formula (1) is 3% or less relative to the entire mixture. 【Chemistry 1】 (In the formula, R 1 each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms; R 2 each independently represents an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, x is a number from 2 to 8, m is an integer from 6 to 12, and n is an integer from 1 to 3.

2. 2. The mixture of sulfur-containing organosilicon compounds according to claim 1, wherein the area percentage of the organic compound represented by formula (1) relative to the entire mixture is 94% or more in gel permeation chromatography.

3. A rubber composition comprising the mixture of sulfur-containing organosilicon compounds according to claim 1 or 2.

4. The rubber composition of claim 3, comprising a diene rubber and a filler.

5. A tire formed by molding the rubber composition according to claim 3.

6. A cured product of the rubber composition according to claim 3.

7. A tire using the cured product according to claim 6.

8. An organosilicon compound represented by the following formula (2), NaSH, Na 2 S and Na 2 S y (wherein y is a number from 2 to 8) and one or more aqueous solutions or dispersions selected from the group consisting of sulfur-containing metal compounds represented by the formula (I) and their hydrates, are reacted in the presence of a phase transfer catalyst. 【Chemistry 2】 (In the formula, R 1 , R 2 , m and n have the same meanings as above.)

9. 9. The method for producing a mixture of sulfur-containing organosilicon compounds according to claim 8, which comprises reacting an organosilicon compound represented by formula (2), an aqueous solution or dispersion of one or more selected from the sulfur-containing metal compounds and hydrates thereof, and sulfur in the presence of a phase transfer catalyst.

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