Organopolysiloxane, rubber composition, and tire

Abstract

This organopolysiloxane represented by formula (1) can, when added to a rubber composition, be used to achieve a tire having desired fuel efficiency and exhibiting excellent hardness, tensile properties, rolling resistance, and wet grip properties.　(1): (R1)a(R2)b(OR3)c(R4)dSiO(4-a-b-c-d) / 2 (In the formula, the R1 moieties each independently represent a mercapto group-containing organic group, the R2 moieties each independently represent an aryl group having 6-10 carbon atoms or an aralkyl group having 7-10 carbon atoms, the R3 moieties each independently represent a hydrogen atom, an alkyl group having 1-20 carbon atoms, an aryl group having 6-10 carbon atoms, an aralkyl group having 7-10 carbon atoms, or an alkenyl group having 2-10 carbon atoms, the R4 moieties each independently represent an alkyl group having 1-12 carbon atoms, and a, b, c, and d indicate numbers satisfying 0<a<1, 0<b<1, 0<c<3, 0≤d<1, and 0<a+b+c+d<4.)

Description

Organopolysiloxane, rubber composition and tire

[0001] The present invention relates to an organopolysiloxane, a rubber composition, and a tire, and more specifically to an organopolysiloxane having a mercapto group-containing organic group and an aryl group or aralkyl group, a rubber composition, and a tire.

[0002] Tires made of silica-filled rubber compositions have excellent performance in automotive applications, particularly in terms of abrasion resistance, rolling resistance, and wet grip. Improvements in these performances are closely related to improvements in tire fuel economy, and therefore have been the subject of intensive research in recent years.

[0003] In order to improve fuel economy, it is essential to increase the silica loading rate of the rubber composition. Although silica-filled rubber compositions reduce tire rolling resistance and improve wet grip, they have high unvulcanized viscosities, require multi-stage kneading, and have workability issues. Therefore, rubber compositions that simply incorporate inorganic fillers such as silica suffer from insufficient filler dispersion, resulting in significant decreases in fracture strength and abrasion resistance. Therefore, sulfur-containing organosilicon compounds are essential to improve the dispersibility of the inorganic filler in the rubber and to chemically bond the inorganic filler to the rubber matrix.

[0004] As sulfur-containing organosilicon compounds, compounds containing alkoxysilyl groups and polysulfide silyl groups in the molecule, such as bis-triethoxysilylpropyl tetrasulfide and bis-triethoxysilylpropyl disulfide, are known to be effective (see Patent Documents 1 to 4). In addition to the above organosilicon compounds having polysulfide groups, the use of thioester-type organosilicon compounds containing blocked mercapto groups, which are advantageous for silica dispersibility, and sulfur-containing organosilicon compounds in which an amino alcohol compound is transesterified with a hydrolyzable silyl group moiety, which is advantageous for affinity with silica through hydrogen bonding, are also known (see Patent Documents 5 to 9).

[0005] However, even when the sulfur-containing organosilicon compounds disclosed in the above-mentioned patent documents are used, it has not yet been possible to obtain a rubber composition for a tire that achieves the desired fuel economy. Furthermore, these sulfur-containing organosilicon compounds are more expensive than sulfide-type compounds, and the production methods are complicated, resulting in productivity problems, and various other issues remain.

[0006] Furthermore, Patent Document 10 discloses an example in which a polysiloxane having a mercapto group and a long-chain alkyl group is used, and although a tire obtained from this composition has improved rolling resistance and wet grip performance, there is a problem in that the hardness decreases.

[0007] Japanese Patent Publication No. 2004-525230, Japanese Patent Laid-Open No. 2004-18511, Japanese Patent Laid-Open No. 2002-145890, U.S. Patent No. 6,229,036, Japanese Patent Laid-Open No. 2005-8639, Japanese Patent Laid-Open No. 2008-150546, Japanese Patent Laid-Open No. 2010-132604, Japanese Patent No. 4,571,125, U.S. Patent No. 6,414,061, Japanese Patent No. 5,339,008

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an organopolysiloxane that, when added to a rubber composition, is excellent in hardness, tensile properties, rolling resistance, and wet grip properties, and can realize a desired fuel-efficient tire, as well as a rubber composition and a tire containing this organopolysiloxane.

[0009] As a result of extensive research into achieving the above-mentioned object, the present inventors have found that, when added to a rubber composition, an organopolysiloxane containing a mercapto group-containing organic group, an aryl group or aralkyl group, and a hydrolyzable group and / or a hydroxyl group can improve rolling resistance and wet grip performance without reducing the hardness or tensile properties of the cured product, and that this rubber composition can achieve the desired fuel-efficient tire properties, thereby completing the present invention.

[0010] That is, the present invention provides: 1. an organopolysiloxane represented by the following formula (1), (R 1 ) a (R 2 ) b (OR 3) c (R 4 ) d SiO (4-a-b-c-d) / 2 (1) (wherein, R 1 each independently represents a mercapto group-containing organic group, R 2 each independently represents an aryl group having 6 to 10 carbon atoms or an aralkyl group having 7 to 10 carbon atoms; R 3 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 4 each independently represents an alkyl group having 1 to 12 carbon atoms, and a, b, c, and d represent numbers that satisfy the following conditions: 0<a<1, 0<b<1, 0<c<3, 0≦d<1, and 0<a+b+c+d<4.) 2. The R 2 is a phenyl group; 3. A rubber composition containing the organopolysiloxane of 1 or 2; 4. A rubber composition of 3 containing a diene rubber and a filler; and 5. A tire obtained by molding the rubber composition of 3.

[0011] A rubber composition containing the organopolysiloxane of the present invention gives a cured product after vulcanization that exhibits excellent hardness, tensile properties, wet grip properties, and low rolling resistance, and a tire formed using this rubber composition can achieve fuel-efficient tire properties.

[0012] The present invention will be specifically described below. [1] Organopolysiloxane The organopolysiloxane according to the present invention is represented by the following formula (1): (R 1 ) a (R 2 ) b (OR 3 ) c (R 4 ) d SiO (4-a-b-c-d) / 2 (1)

[0013] In the above formula (1), R 1 are each independently a mercapto group-containing organic group, and a group represented by the following formula (2) is preferred: *—(CH) n-SH (2) (wherein n represents an integer of 1 to 10, and *- represents a bond; the same applies below.) Specific examples of the mercapto group-containing organic group include, but are not limited to, the groups shown below: *-CH2SH *-C2H4SH *-C3H6SH *-C4H8SH *-C5H 10 SH *-C6H 12 SH *-C7H 14 SH *-C8H 16 SH *-C9H 18 SH *-C 10 H 20 SH

[0014] R 2 each independently represents an aryl group having 6 to 10 carbon atoms or an aralkyl group having 7 to 10 carbon atoms. Specific examples of aryl groups having 6 to 10 carbon atoms include phenyl, tolyl, xylyl, and naphthyl groups. Specific examples of aralkyl groups having 7 to 10 carbon atoms include phenylmethyl (benzyl), and phenylethyl groups. Among these, R 2 As the alkyl group, a phenyl group is preferred.

[0015] R 3 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. Specific examples of the alkyl group having 1 to 20 carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-hexyl, n-octyl, n-decyl, and octadecyl groups. Specific examples of the alkenyl group having 2 to 10 carbon atoms include vinyl, propenyl, and pentenyl groups. Examples of the aryl group having 6 to 10 carbon atoms and the aralkyl group having 7 to 10 carbon atoms include the groups listed above for R 2 Among these, R 3 is preferably a hydrogen atom, a methyl group, or an ethyl group, more preferably an ethyl group.

[0016] R 4 each independently represents an alkyl group having 1 to 12 carbon atoms, and specific examples thereof include the above-mentioned R 3Among the alkyl groups having 1 to 20 carbon atoms exemplified above, those having 1 to 12 carbon atoms can be mentioned. Among these, from the viewpoint of improving the processability by reducing the viscosity of the rubber composition and further improving fuel economy, R 4 As the alkyl group, an alkyl group having 6 to 12 carbon atoms is preferred.

[0017] a, b, c, and d represent the average number of moles of each organic group when the total number of moles of silicon atoms is taken as 1, and represent numbers that satisfy 0<a<1, 0<b<1, 0<c<3, 0≦d<1, and 0<a+b+c+d<4, but are preferably numbers that satisfy 0.05≦a≦0.9, 0.1≦b≦0.8, 1.0≦c≦2.5, 0≦d≦0.6, and 1.2≦a+b+c+d<4, and more preferably numbers that satisfy 0.1≦a≦0.2, 0.4≦b≦0.8, 1.0≦c≦2.5, 0≦d≦0.4, and 1.5≦a+b+c+d<4.

[0018] In the present invention, the kinematic viscosity of the organopolysiloxane at 25°C as measured by a capillary kinematic viscometer is preferably 2 to 10,000 mm from the viewpoint of processability. 2 / s is preferred, and 10 to 5,000 mm 2 / s is more preferred.

[0019] The organopolysiloxane of the present invention can be produced, for example, by co-hydrolytic condensation of an organosilicon compound represented by the following general formula (3), an organosilicon compound represented by the following general formula (4), and, if necessary, an organosilicon compound represented by the following general formula (5).

[0020] (In the formula, R 3 and n have the same meaning as above, R 5 each independently represents an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 10 carbon atoms, and y represents an integer of 1 to 3, preferably 2 or 3.

[0021] (In the formula, R 2 , R 3 , R 5 and y have the same meaning as above.

[0022] (In the formula, R 3 , R 4 and y have the same meaning as above.

[0023] R 5 The alkyl group having 1 to 12 carbon atoms, the aryl group having 6 to 10 carbon atoms, and the aralkyl group having 7 to 10 carbon atoms are the same as those of the above R 2 and R 4 Among these, R 5 As the alkyl group, an alkyl group having 1 to 3 carbon atoms is preferred, and a methyl group is more preferred.

[0024] Specific examples of organosilicon compounds represented by the above formula (3) include 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 8-mercaptooctyltriethoxysilane, 8-mercaptooctyltrimethoxysilane, etc. Specific examples of organosilicon compounds represented by the above formula (4) include phenyltriethoxysilane, phenyltrimethoxysilane, phenyldiethoxymethylsilane, phenyldimethoxymethylsilane, etc. Specific examples of organosilicon compounds represented by the above formula (5) include methyltriethoxysilane, methylethyldiethoxysilane, propyltriethoxysilane, propylmethyldiethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, decyltriethoxysilane, etc.

[0025] The amounts of the organosilicon compounds represented by the formulas (3), (4), and (5) used are selected so that a to d are the numbers described above in the formula (1). Based on the total amount of the organosilicon compounds represented by the formulas (3), (4), and (5), the organosilicon compound represented by the formula (3) is preferably 5 to 90 mol%, more preferably 10 to 80 mol%, the organosilicon compound represented by the formula (4) is preferably 10 to 80 mol%, more preferably 20 to 80 mol%, and the organosilicon compound represented by the formula (5) is preferably 0 to 60 mol%, more preferably 0 to 50 mol%.

[0026] The co-hydrolytic condensation can be carried out by a known method, and the amount of water used can also be a known amount, typically 0.5 to 0.99 mol, preferably 0.6 to 0.95 mol, per mol of the total number of hydrolyzable silyl groups in the organosilicon compound.

[0027] An organic solvent may be used, if necessary, in the production of the organopolysiloxane of the present invention. Specific examples of organic solvents include aliphatic hydrocarbon solvents such as pentane, hexane, heptane, and decane; ether solvents such as diethyl ether, tetrahydrofuran, and 1,4-dioxane; amide solvents such as formamide, dimethylformamide, and N-methylpyrrolidone; aromatic hydrocarbon solvents such as benzene, toluene, and xylene; and alcohol solvents such as methanol, ethanol, and propanol. Among these, ethanol and i-propanol are preferred from the viewpoint of excellent hydrolysis reactivity. When using such solvents, the amount used is not particularly limited, but is preferably no more than about twice the mass of the organosilicon compound, and particularly preferably no more than the mass of the organosilicon compound.

[0028] Furthermore, a catalyst may be used, if necessary, in the production of the organopolysiloxane of the present invention. Specific examples of catalysts include acidic catalysts such as hydrochloric acid and acetic acid; Lewis acid catalysts such as tetrabutyl orthotitanate and ammonium fluoride; alkali metal salts such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium acetate, potassium acetate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, calcium carbonate, sodium methoxide, and sodium ethoxide; and amine compounds such as triethylamine, tributylamine, pyridine, and 4-dimethylaminopyridine. Hydrochloric acid, for example, can be used as a catalyst for the silane hydrolysis (and / or partial condensation), and potassium hydroxide, for example, can be used as a catalyst for the silanol condensation (oligomerization). From the viewpoint of excellent reactivity, the amount of catalyst (when a catalyst for the silane hydrolysis reaction and a catalyst for the silanol condensation reaction are used in combination, the respective amounts) is preferably 0.001 to 0.05 (unit: molar equivalent) per mole of the total of hydrolyzable silyl groups in the organosilicon compound.

[0029] The reaction conditions for the co-hydrolysis condensation are generally 20 to 100°C, preferably 60 to 85°C, and generally 30 minutes to 20 hours, preferably 1 minute to 10 hours.

[0030] [2] Rubber Composition The rubber composition of the present invention contains the organopolysiloxane (A) represented by the above formula (1), and may further contain a diene rubber (B) and a filler (C). 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 organopolysiloxane (A) represented by the above formula (1) compounded is preferably 0.1 to 10 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of the filler (C) described below.

[0031] As the diene rubber (B), any rubber that has conventionally been generally used in various rubber compositions can be used, and specific examples thereof include diene rubbers such as natural rubber (NR); 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.

[0032] Examples of the filler (C) include silica, talc, clay, aluminum hydroxide, magnesium hydroxide, calcium carbonate, and titanium oxide. Among these, silica is preferred, and the rubber composition of the present invention is more preferably used as a silica-containing rubber composition. In this case, the amount of filler (C) is preferably 5 to 200 parts by mass, more preferably 30 to 120 parts by mass, per 100 parts by mass of diene rubber, taking into consideration the physical properties of the resulting rubber and the balance between the degree of effect exerted and economic efficiency.

[0033] In addition to the above-mentioned component (A), the rubber compounding agent of the present invention can contain (D), an organosilicon compound having at least one selected from a polysulfide group, a thioester group, and a mercapto group, and an alkoxysilyl group. 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 compounded in rubber compositions for use in tires and the like can be used.

[0034] 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 organosilicon compounds having sulfur atoms 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 (B) may be used alone or in combination of two or more types.

[0035] In addition to the above components (A) to (D), the rubber composition of the present invention may contain various additives that are generally compounded in tires and other general rubbers, such as carbon black, vulcanizing agents, crosslinking agents, vulcanization accelerators, crosslinking accelerators, various oils, antioxidants, plasticizers, etc. The amounts of these additives may be conventional amounts as long as they do not deviate from the object of the present invention.

[0036] The rubber composition of the present invention can be obtained by adding the organopolysiloxane (A), the filler (C), and other components to the diene rubber (B) and kneading them in a conventional manner.

[0037] [3] Rubber Product (Tire) The rubber composition of the present invention can be used to produce a rubber product, such as a tire, by preparing a composition from the above-described components (A) to (C) and other components by a general method and vulcanizing or crosslinking the composition. In particular, when producing a tire, it is preferable that the rubber composition of the present invention be used in the tread.

[0038] A tire obtained using the rubber composition of the present invention has significantly reduced rolling resistance and significantly improved wear resistance, thereby achieving the desired low fuel consumption. 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 may be normal air, air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium.

[0039] 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. In the following examples, "parts" means parts by mass, viscosity is a value measured at 25°C using a capillary kinematic viscometer, and weight average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC) in terms of polystyrene.

[0040] [1] Synthesis of Organopolysiloxane [Example 1-1] 238 g (1.0 mol) of 3-mercaptopropyltriethoxysilane (KBE-803, manufactured by Shin-Etsu Chemical Co., Ltd.), 960 g (4.0 mol) of phenyltriethoxysilane (KBE-103, manufactured by Shin-Etsu Chemical Co., Ltd.), and 400 g of ethanol were placed in a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, and then 78.8 g of 0.5 N hydrochloric acid (4.4 mol of water) was added dropwise at room temperature. The mixture was then stirred at 80°C for 10 hours. Thereafter, 2.0 g of propylene oxide was added dropwise, and the mixture was stirred at 80°C for 2 hours. The mixture was then concentrated under reduced pressure and filtered to obtain a 1000 ml organopolysiloxane having a viscosity of 40 mm. 2 A colorless, transparent liquid having a molecular weight of 1,400 and a mercapto equivalent of 870 g / mol was obtained. The resulting organopolysiloxane was represented by the following formula (—C H —SH): 0.20(-C6H5) 0.80 (-OC2H5) 1.25 SiO 0.88

[0041] Example 1-2 A 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer was charged with 238 g (1.0 mol) of 3-mercaptopropyltriethoxysilane (KBE-803, manufactured by Shin-Etsu Chemical Co., Ltd.), 960 g (4.0 mol) of phenyltriethoxysilane (KBE-103, manufactured by Shin-Etsu Chemical Co., Ltd.), and 400 g of ethanol, and then 68.4 g of 0.5 N hydrochloric acid (3.8 mol of water) was added dropwise at room temperature. The mixture was then stirred at 80°C for 10 hours. Thereafter, 2.0 g of propylene oxide was added dropwise, and the mixture was stirred at 80°C for 2 hours. The mixture was then concentrated under reduced pressure and filtered to obtain a solution having a viscosity of 16 mm. 2 A colorless, transparent liquid having a molecular weight of 1000 g / mol was obtained. The resulting organopolysiloxane was represented by the following formula, had a molecular weight of 750, and a mercapto equivalent of 910 g / mol (-CH-SH). 0.20 (-C6H5) 0.80 (-OC2H5) 1.50 SiO 0.75

[0042] Example 1-3 A 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer was charged with 238 g (1.0 mol) of 3-mercaptopropyltriethoxysilane (KBE-803, manufactured by Shin-Etsu Chemical Co., Ltd.), 721 g (3.0 mol) of phenyltriethoxysilane (KBE-103, manufactured by Shin-Etsu Chemical Co., Ltd.), 277 g (1.0 mol) of octyltriethoxysilane (KBE-3083, manufactured by Shin-Etsu Chemical Co., Ltd.), and 400 g of ethanol, and then 68.4 g of 0.5 N hydrochloric acid (3.8 mol of water) was added dropwise at room temperature. The mixture was then stirred at 80°C for 10 hours. Thereafter, 2.0 g of propylene oxide was added dropwise, and the mixture was stirred at 80°C for 2 hours. The mixture was then concentrated under reduced pressure and filtered to obtain a solution having a viscosity of 11 mm. 2 A colorless, transparent liquid having a molecular weight of 770 and a mercapto equivalent of 950 g / mol was obtained. The resulting organopolysiloxane was represented by the following formula (—C3H6—SH): 0.20 (-C6H5) 0.60 (-C8H17 ) 0.20 (-OC2H5) 1.50 SiO 0.75

[0043] [Example 1-4] 238 g (1.0 mol) of 3-mercaptopropyltriethoxysilane (KBE-803, manufactured by Shin-Etsu Chemical Co., Ltd.), 480 g (2.0 mol) of phenyltriethoxysilane (KBE-103, manufactured by Shin-Etsu Chemical Co., Ltd.), 553 g (2.0 mol) of octyltriethoxysilane (KBE-3083, manufactured by Shin-Etsu Chemical Co., Ltd.), and 400 g of ethanol were placed in a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, and then 68.4 g of 0.5 N hydrochloric acid (3.8 mol of water) was added dropwise at room temperature. The mixture was then stirred at 80°C for 10 hours. Thereafter, 2.0 g of propylene oxide was added dropwise, and the mixture was stirred at 80°C for 2 hours. The mixture was then concentrated under reduced pressure and filtered to obtain a solution having a viscosity of 11 mm. 2 A colorless, transparent liquid having a molecular weight of 1000 g / mol was obtained. The resulting organopolysiloxane was represented by the following formula, had a molecular weight of 790, and a mercapto equivalent of 990 g / mol: (—C3H6—SH) 0.20 (-C6H5) 0.40 (-C8H 17 ) 0.40 (-OC2H5) 1.50 SiO 0.75

[0044] Example 1-5 A 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer was charged with 238 g (1.0 mol) of 3-mercaptopropyltriethoxysilane (KBE-803, manufactured by Shin-Etsu Chemical Co., Ltd.), 480 g (2.0 mol) of phenyltriethoxysilane (KBE-103, manufactured by Shin-Etsu Chemical Co., Ltd.), 413 g (2.0 mol) of propyltriethoxysilane (KBE-3033, manufactured by Shin-Etsu Chemical Co., Ltd.), and 400 g of ethanol, and then 68.4 g of 0.5 N hydrochloric acid (3.8 mol of water) was added dropwise at room temperature. The mixture was then stirred at 80°C for 10 hours. Thereafter, 2.0 g of propylene oxide was added dropwise, and the mixture was stirred at 80°C for 2 hours. The mixture was then concentrated under reduced pressure and filtered to obtain a solution with a viscosity of 13 mm. 2A colorless, transparent liquid having a molecular weight of 1000 g / mol was obtained. The resulting organopolysiloxane was represented by the following formula, had a molecular weight of 680, and a mercapto equivalent of 850 g / mol: (—C3H6—SH) 0.20 (-C6H5) 0.40 (-C8H 17 ) 0.40 (-OC2H5) 1.50 SiO 0.75

[0045] Comparative Example 1-1: 238 g (1.0 mol) of 3-mercaptopropyltriethoxysilane (KBE-803, manufactured by Shin-Etsu Chemical Co., Ltd.), 1106 g (4.0 mol) of octyltriethoxysilane (KBE-3083, manufactured by Shin-Etsu Chemical Co., Ltd.), and 400 g of ethanol were placed in a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, and then 68.4 g of 0.5 N hydrochloric acid (3.8 mol of water) was added dropwise at room temperature. The mixture was then stirred at 80°C for 10 hours. Thereafter, 2.0 g of propylene oxide was added dropwise, and the mixture was stirred at 80°C for 2 hours. The mixture was then concentrated under reduced pressure and filtered to obtain a solution having a viscosity of 16 mm. 2 A colorless, transparent liquid having a molecular weight of 1,060 g / mol was obtained. The resulting organopolysiloxane was represented by the following formula (—C H —SH), had a molecular weight of 850, and a mercapto equivalent of 1,060 g / mol. 0.20 (-C8H 17 ) 0.80 (-OC2H5) 1.50 SiO 0.75

[0046] [2] Preparation of Rubber Compositions [Examples 2-1 to 2-6, Comparative Examples 2-1 to 2-2] 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 components, carbon black, silica, sulfide silane, organopolysiloxanes obtained in the Examples and Comparative Examples, 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 and kneaded to obtain a rubber composition.

[0047] SBR: SLR-4602 (manufactured by Trinseo) BR: BR-01 (manufactured by JSR Corporation) Oil: AC-12 (manufactured by Idemitsu Kosan Co., Ltd.) Carbon black: Seast 3 (manufactured by Tokai Carbon Co., Ltd.) Silica: Nipsil AQ (manufactured by Tosoh Silica Corporation) Sulfide silane: KBE-846 (manufactured by Shin-Etsu Chemical Co., Ltd.) 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.)

[0048] The unvulcanized and vulcanized physical properties of the rubber compositions obtained in Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-2 were measured by the following methods. The results are shown in Tables 1 and 2. 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).

[0049] [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 room temperature. 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 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%)] is 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.

[0050]

[0051] As shown in Table 1, the rubber compositions of Examples 2-1 to 2-6 were found to have good hardness, tensile properties, silica dispersibility, wet grip properties, and rolling resistance after vulcanization. On the other hand, the rubber composition of Comparative Example 2-2, which used a mercapto group-containing organopolysiloxane that did not have an aryl group or aralkyl group bonded to a silicon atom, was found to have poor hardness and tensile properties after vulcanization.

Claims

1. An organopolysiloxane represented by the following formula (1): (R 1 ) a (R 2 ) b (OR 3 ) c (R 4 ) d SiO (4-a-b-c-d) / 2 (1) (wherein, R 1 each independently represents a mercapto group-containing organic group, R 2 each independently represents an aryl group having 6 to 10 carbon atoms or an aralkyl group having 7 to 10 carbon atoms; R 3 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 4 each independently represents an alkyl group having 1 to 12 carbon atoms, and a, b, c, and d represent numbers that satisfy the following conditions: 0<a<1, 0<b<1, 0<c<3, 0≦d<1, and 0<a+b+c+d<4.) 2. The above R 2 2. The organopolysiloxane of claim 1, wherein is a phenyl group.

3. A rubber composition containing the organopolysiloxane of 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.

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