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

Abstract

Provided is a mixture of sulfur-containing organosilicon compounds, wherein the percentage of the area occupied by an organic compound represented by formula (1) is 90% or more relative to the total mixture, and the percentage of the area occupied by a dimer of organic compounds represented by formula (1) is 3% or less relative to the total mixture, as measured by gel permeation chromatography. (In the formula, R1 represents a hydrogen atom, 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 2-8; m is an integer of 6-12; and n is an integer of 1-3.)

Description

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

[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.

[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 loading rate of rubber compositions, but rubber compositions that simply incorporate inorganic fillers such as silica lack sufficient filler dispersibility, resulting in high unvulcanized viscosity, the need for multi-stage kneading, and other workability issues, 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] As sulfur-containing organosilicon compounds, 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), and 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).

[0005] Japanese Patent Publication No. 2004-525230, Japanese Patent Application Laid-Open No. 2004-18511, Japanese Patent Application Laid-Open No. 2002-145890, U.S. Patent No. 6,229,036, Japanese Patent Application Laid-Open No. 2018-65954, Japanese Patent Application Laid-Open No. 2018-123260, Japanese Patent Application Laid-Open No. 2020-100847

[0006] However, in the past, when producing these sulfur-containing organosilicon compounds, it was unavoidable to mix in polymers 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.

[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 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, 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, in which, in gel permeation chromatography, the area percentage occupied by the organic compound represented by the following formula (1) is 90% or more relative to the entire mixture, and the area percentage occupied by the dimer of the organic compound represented by the following formula (1) is 3% or less relative to the entire mixture; (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 2each independently represent 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. A mixture of sulfur-containing organosilicon compounds as set forth in 1, in which the area percentage occupied by 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 as set forth in 1 or 2; 4. A rubber composition as set forth in 3, which contains a diene rubber and a filler; 5. A tire obtained by molding the rubber composition as set forth in 3 or 4; 6. A cured product of the rubber composition as set forth in 3 or 4; 7. A tire using the cured product as set forth in 6; 8. A rubber composition as set forth in 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. (In the formula, R 1 , R 2 , m, and n have the same meanings as above.) 9. Provided is a method for producing a mixture of sulfur-containing organosilicon compounds according to 8, which comprises reacting an organosilicon compound represented by formula (2) with an aqueous solution or aqueous 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.

[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.

[0011] The present invention will be described in detail 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]

[0013] In formula (1), R 1 R 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. 1 The alkyl group having 1 to 20 carbon atoms may be linear, branched, or cyclic, and preferably has 1 to 10 carbon atoms, more preferably has 1 to 8 carbon atoms, and even more preferably has 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 preferably has 6 to 8 carbon atoms, and specific examples thereof include phenyl and tolyl groups. The aralkyl group having 7 to 10 carbon atoms preferably has 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, and more preferably has 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 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, and the properties of the formed tire are deteriorated.

[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) include, but are not limited to, the compounds shown below. In the following formula, Me represents a methyl group and Et represents an ethyl group (the same applies hereinafter): (EtO)Si-CH 12 -S2-C6H 12 -Si(OEt)3 (EtO)2MeSi-C6H 12 -S2-C6H 12 -SiMe(OEt)2 (EtO)3Si-C6H 12 -S4-C6H 12 -Si(OEt)3 (EtO)2MeSi-C6H 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-C9H 18 -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-C 12 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) is 90% or more, preferably 92% or more, more preferably 94% or more, based on the total area of ​​the mixture, as determined by gel permeation chromatography, and the area percentage of the dimer of the organic compound represented by formula (1) is 3% or less, based on the total area of ​​the mixture. If the organic compound represented by formula (1) and the dimer of the organic compound represented by formula (1) are outside the above ranges, 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 hydrates thereof, by reacting an aqueous solution or an aqueous dispersion of one or more compounds selected from these sulfur-containing metal compounds and hydrates thereof with sulfur, if necessary, in the presence of a phase transfer catalyst.

[0021] (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) include, but are not limited to, the compounds shown below: (EtO)3Si-C6H 12 -Cl(EtO)2MeSi-CH 12 -Cl(EtO)3Si-C7H 14 -Cl(EtO)2MeSi-CH 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-C10 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 aqueous dispersion of the sulfur-containing metal compound and / or its hydrate is not particularly limited, but the total amount of water added is preferably 10 to 200 parts by mass, and more preferably 30 to 100 parts by mass, per 100 parts by mass of the organosilicon compound represented by formula (2).

[0024] In the production method of the present invention, when sulfur is used, 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 to sulfur, can be adjusted in accordance with the desired average number x of sulfur atoms in formula (1). For example, when a sulfur-containing metal compound, a hydrate thereof, and sulfur are used, sulfur may 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, and examples thereof include quaternary ammonium cation compounds, quaternary phosphonium cation compounds, crown ether compounds, etc. Examples of quaternary ammonium cation compounds include, but are not particularly limited to, 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, with tetra-n-butylammonium bromide and tetra-n-butylammonium chloride being preferred. Examples of quaternary phosphonium cation compounds include tetra-n-butylphosphonium chloride, tetra-n-butylphosphonium bromide, tetraphenylphosphonium bromide, triphenylmethylphosphonium bromide, and triphenylmethylphosphonium chloride, with tetra-n-butylphosphonium bromide being preferred.

[0027] The amount of the phase transfer catalyst added is not limited, 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 formula (2) above.

[0028] In the above reaction, an organic solvent may be used if necessary. 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 generally 20 to 100°C, preferably 60 to 85°C, and generally 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 target layer and an aqueous layer, and the target product can be separated. If a salt precipitates, water can be added to dissolve the salt, or filtration can be performed before and / or after separation. If a solvent is used, it can 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) Mixture of Sulfur-Containing Organosilicon Compounds Component (A) is a mixture of the sulfur-containing organosilicon compounds described above. 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, and 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 that has been conventionally used in various rubber compositions, and specific examples thereof include natural rubber (NR); diene rubbers such as various isoprene rubbers (IR), various styrene-butadiene copolymer rubbers (SBR), various polybutadiene rubbers (BR), and acrylonitrile-butadiene copolymer rubbers (NBR), and these 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, clay, etc. These may be used alone or in combination of two or more. Among these, it is preferable that the rubber composition of the present invention 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 those commonly used in the tire industry, such as silica prepared by a dry method (anhydrous silica) and silica prepared by a wet method (hydrated silica). Among these, silica prepared by a wet method is preferred because it contains a large number of silanol groups. In particular, silica having a nitrogen adsorption specific surface area (N2SA) of 70 m 2 / g or more is preferred, 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 use (D) a silane coupling agent having at least one selected from a polysulfide group, a thioester group, and a mercapto group, and an alkoxysilyl group. The component (D) is not particularly limited as long as it is a compound having such a functional group, and for example, any conventionally known silane coupling agent that is 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 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.

[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. For example, products available from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., and Hosoi Chemical Industry Co., Ltd. can be used as the sulfur.

[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 Product (Tire) 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 not only reduces rolling resistance but also improves wet grip performance, thereby achieving the desired fuel economy. The tire structure can be a conventionally known structure, and the manufacturing method thereof may also be a conventionally known manufacturing method. In the case of a gas-filled tire, the gas to be filled in the tire can usually be air, air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium.

[0044] The present invention will be described 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 (manufactured by Tosoh Corporation) Detector: RI Column: TSKgel GMHXL-L (manufactured by Tosoh Corporation) TSKgel Super H4000 (manufactured by Tosoh Corporation) TSKgel Super H2000 (manufactured by Tosoh Corporation) Solvent: tetrahydrofuran Flow rate: 0.6 mL / min Standard: polystyrene

[0045] [1] Production of a mixture of sulfur-containing organosilicon compounds [Example 1-1] In a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 40.0 g (1.0 mol) of sodium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd.) and 224 g (1.0 mol) of an aqueous NaSH solution (manufactured by Nagao Co., Ltd., concentration 25% by mass) were placed and stirred at 80 ° C. for 1 hour. Thereafter, 96.3 g (3.0 mol) of sulfur (manufactured by Tokyo Chemical Industry Co., Ltd.) and 195 g of water were placed and stirred at 80 ° C. for 1 hour. Thereafter, 4.3 g of tetra-n-butylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) was placed 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 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 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 the mixture was 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, followed by filtration, yielding 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] Example 1-3 581 g (1.0 mol) of an aqueous solution of Na2S4 (manufactured by Nagao Co., Ltd., concentration 30% by mass) was placed in a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, and heated to 80°C. Then, 4.3 g of tetra-n-butylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) was placed in the flask, and 622 g (2.0 mol) of (8-chlorooctyl)triethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise at 80°C over a period of 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, followed by filtration, yielding 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] Example 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 the mixture was 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 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 completion of the dropwise addition, the mixture was stirred for 3 hours, and the aqueous layer was removed by liquid separation at 25°C. Subsequently, the mixture was concentrated under reduced pressure at 80°C, followed by filtration, yielding 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] Example 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 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 the mixture was stirred at 80°C for 1 hour. Subsequently, 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 completion of the dropwise addition, the mixture was stirred for 5 hours, and the aqueous layer was removed by liquid separation at 25°C. Subsequently, the mixture was concentrated under reduced pressure at 80°C, followed by filtration, yielding 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] Example 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 NaS 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 completion of 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, followed by filtration, yielding 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: 78.0 g (1.0 mol) of anhydrous sodium sulfide (manufactured by Nagao Co., Ltd.), 96.3 g (3.0 mol) of sulfur (manufactured by Tokyo Chemical Industry Co., Ltd.), and 500 g of ethanol were placed in a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, and stirred at 80°C for 1 hour. 622 g (2.0 mol) of (8-chlorooctyl)triethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added thereto, and the mixture was 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 620 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 90%, and the content of its dimer was 7%.

[0052] Comparative Example 1-2: 78.0 g (1.0 mol) of anhydrous sodium sulfide (manufactured by Nagao Co., Ltd.), 48.2 g (1.5 mol) of sulfur (manufactured by Tokyo Chemical Industry Co., Ltd.), and 500 g of ethanol were placed in a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, and stirred at 80°C for 1 hour. 622 g (2.0 mol) of (8-chlorooctyl)triethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added thereto, 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 580 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 90%, and the content of its dimer was 7%.

[0053] [2] Preparation of Rubber Compositions [Examples 2-1 to 2-5, Comparative Example 2-1] Using a 4 L internal mixer (MIXTRON, manufactured by Kobe Steel, Ltd.), SBR and BR listed in Table 1 were kneaded for 30 seconds. 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, and the internal temperature was raised to 150°C. After holding at 150°C for 2 minutes, the mixture was discharged. It was then stretched using a roll. 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 stretched using a roll. Zinc oxide, vulcanization accelerator, and sulfur listed in Table 1 were added to the mixture and kneaded to obtain a rubber composition.

[0054] SBR: SLR-4602 (manufactured by Trinseo) BR: BR-01 (manufactured by JSR Corporation) Oil: AC-12 (manufactured by Idemitsu Kosan Co., Ltd.) Carbon black: Seest 3 (manufactured by Tokai Carbon Co., Ltd.) Silica: Nipsil AQ (manufactured by Tosoh Silica Corporation) Stearic acid: industrial stearic acid (manufactured by Kao Corporation) Anti-aging agent: Nocrac 6C (manufactured by 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 and 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 (manufactured by 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 prepare vulcanized rubber sheets (thickness 2 mm).

[0056] [Unvulcanized physical properties] (1) Mooney viscosity Measured in accordance with JIS K 6300-1:2013 with 1 minute of preheating, 4 minutes of measurement, and at a temperature of 130°C, and expressed as an index with Comparative Example 2-1 as 100. The smaller the index value, the lower the Mooney viscosity and the better the processability. [Vulcanized physical 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 as 100. The larger the index value, the higher the hardness and the better the performance. (3) Tensile properties JIS No. 3 dumbbell-shaped test pieces were punched out, and a tensile test was carried out in accordance with JIS K6251 at a tensile speed of 500 mm / min to measure 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 100. A larger index value indicates a higher modulus and better tensile properties. (4) Dynamic Viscoelasticity (Strain Dispersion) Using a viscoelasticity measuring device (manufactured by 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 a frequency of 55 Hz, and the value of [E' (0.5%) - E' (3.0%)] was calculated. A sheet with a thickness of 0.2 cm and a width of 0.5 cm was used as the test specimen, with a clamp distance of 2 cm and an initial load of 1 N. The value of [E' (0.5%) - E' (3.0%)] was expressed as an index, with Comparative Example 2-1 being 100. A smaller index value indicates better silica dispersibility. (5) Dynamic viscoelasticity (temperature dispersion) Using a viscoelasticity measuring device (manufactured by Metrabib), measurements were taken under conditions of a tensile dynamic strain of 1% and a frequency of 55 Hz. The test specimens were sheets 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 values ​​of tan δ (0 ° C) and tan δ (60 ° C) were expressed as indices, with Comparative Example 2-1 being 100. The larger the index value of tan δ (0 ° C), the better the wet grip performance. The smaller the index value of tan δ (60 ° C), the better the rolling resistance. (6) Abrasion Resistance Using an FPS tester (manufactured by Ueshima Seisakusho), the test was conducted under conditions of a sample speed of 200 m / min, a load of 20 N, a road surface temperature of 30 ° C, and a slip ratio of 5%. The obtained results were expressed as an index, with Comparative Example 2-1 being 100. The larger the index value, the less wear there was and the better the abrasion resistance.

[0057]

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

Claims

1. 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 of 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 of the entire mixture. (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 claim 1, wherein the area percentage of the organic compound represented by formula (1) in gel permeation chromatography is 94% or more of the entire mixture.

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, which comprises a diene rubber and a filler.

5. A tire formed by molding the rubber composition according to claim 3 or 4.

6. A cured product of the rubber composition according to claim 3 or 4.

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

8. An organosilicon compound represented by the following formula (2) and NaSH, NaS and NaS 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 hydrates thereof, are reacted in the presence of a phase transfer catalyst. (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), 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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