Compounding agent for diene rubbers and rubber composition

Abstract

(A) A compounding agent for diene rubbers containing a silicone resin represented by formula (1) can, when added to a rubber composition, provide a rubber composition that can achieve desired hardness, tensile properties and durability without deteriorating processability, abrasion resistance and low fuel consumption performance of the composition.　Formula (1): (SiO4 / 2)a(R1SiO3 / 2)b(R1 2SiO2 / 2)c(R1 3SiO1 / 2)d(R2O1 / 2)e, wherein in the formula, each R1 independently represents a C1-8 alkyl, aralkyl or aryl group which may be substituted with a hydrogen atom or a halogen atom; at least 50 mol% of R1 is a methyl group; R2 represents a hydrogen atom, a methyl group, an ethyl group, a n-propyl group, an i-propyl group or an acetyl group; at least 20 mol% of R2 is a hydrogen atom; a, b, c and d are numbers satisfying 0≤a<1, 0<b≤1, 0≤c<1, 0≤d<1 and a+b+c+d=1; and e is a number satisfying 0≤e≤2.

Description

Compounding agent for diene rubber and rubber composition

[0001] The present invention relates to a compounding agent for diene rubber and a rubber composition.

[0002] Silica-filled tires have excellent performance in automotive applications, particularly in terms of wear resistance, rolling resistance, and wet grip. These performance improvements are closely related to improved fuel economy, and therefore have recently been the subject of active research, particularly in the passenger car tire industry, where solution-polymerized styrene-butadiene rubber (S-SBR) is used.

[0003] Silica-filled rubber compositions reduce tire rolling resistance and improve wet grip, but have high unvulcanized viscosities, require multi-stage mixing, 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 dispersion of inorganic fillers in rubber and to chemically bond the filler to the rubber matrix.

[0004] As sulfur-containing organosilicon compounds used as compounding agents for rubber, compounds containing an alkoxysilyl group and a polysulfide silyl group in the molecule, such as bis-triethoxysilylpropyl tetrasulfide and bis-triethoxysilylpropyl disulfide, are known to be effective (see Patent Documents 1 to 4).

[0005] Various alkoxysilyl group-containing compounds have been developed to improve the dispersibility of silica, an inorganic filler, and thereby improve fuel economy. However, while these compounds improve fuel economy, they have the problem of not improving hardness or tensile properties. Therefore, there is a need for materials that improve hardness and tensile properties without compromising processability or fuel economy. In this regard, Patent Document 5 proposes a method of improving hardness and tensile properties by adding a silicone resin containing silanol groups to an organic elastomer, but further improvements in hardness, tensile properties, and durability are required.

[0006] JP-T-2004-525230A JP-A-2004-18511 JP-A-2002-145890 JP-A-2000-103795 JP-T-2011-504956

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rubber compounding agent that, when added to a rubber composition, gives a rubber composition that can achieve desired hardness, tensile properties, and durability without deteriorating the processability, abrasion resistance, or fuel economy of the composition; a rubber composition containing this rubber compounding agent; and a tire formed from this rubber composition.

[0008] As a result of intensive research aimed at solving the above problems, the present inventors have found that a specific silicone resin is suitable as a rubber compounding agent, and that a tire obtained from a rubber composition containing this rubber compounding agent can achieve the desired hardness, tensile properties, and durability without deteriorating the processability, wear resistance, or fuel economy of the composition, and have completed the present invention.

[0009] That is, the present invention provides: 1. (A) a compounding agent for diene rubber containing a silicone resin represented by the following formula (1), (SiO 4 / 2 ) a (R 1 SiO 3 / 2 ) b (R 1 2SiO 2 / 2 ) c (R 1 3SiO 1 / 2 ) d (R 2 O 1 / 2 ) e (1) (wherein, R 1 each independently represents a hydrogen atom, or an alkyl group, aralkyl group, or aryl group having 1 to 8 carbon atoms, which may be substituted with a halogen atom; R 1 At least 50 mol % of R are methyl groups, 2 represents a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, or an acetyl group; R 2wherein at least 20 mol % are hydrogen atoms, a, b, c, and d are numbers that satisfy 0≦a<1, 0<b≦1, 0≦c<1, 0≦d<1, and a+b+c+d=1, and e is a number that satisfies 0≦e≦2. 2. The compounding agent for diene rubber of 1, wherein b is a number that satisfies 0.4≦b≦1, 3. The compounding agent for diene rubber of 2, wherein b is 1, 4. The compounding agent for diene rubber of 1, wherein the silicone resin is solid at 25°C, 5. Any of the compounding agents for diene rubber of 1 to 4, further comprising (B) an organosilicon compound having one or more selected from a polysulfide group, a thioester group, and a mercapto group, and an alkoxysilyl group, 6. (A) a silicone resin represented by the following formula (1), (SiO 4 / 2 ) a (R 1 SiO 3 / 2 ) b (R 1 2SiO 2 / 2 ) c (R 1 3SiO 1 / 2 ) d (R 2 O 1 / 2 ) e (1) (wherein, R 1 each independently represents a hydrogen atom, or an alkyl group, aralkyl group, or aryl group having 1 to 8 carbon atoms, which may be substituted with a halogen atom; R 1 At least 50 mol % of R are methyl groups, 2 represents a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, or an acetyl group; R 2 (B) an organosilicon compound having an alkoxysilyl group and one or more selected from a polysulfide group, a thioester group, and a mercapto group; (C) a diene-based rubber; and (D) an inorganic filler. 7. A tire obtained by molding the rubber composition of claim 6.

[0010] The rubber composition containing the rubber compounding agent of the present invention has excellent processability, and a tire formed using this rubber composition can achieve the desired hardness, tensile properties, and durability without deteriorating the wear resistance and fuel economy.

[0011] The present invention will be specifically described below. [Rubber Compounding Agent] The rubber compounding agent of the present invention contains the following component (A).

[0012] [1] (A) Silicone Resin Component (A) is a silicone resin having a constitutional unit ratio represented by the following formula (1): (SiO 4 / 2 ) a (R 1 SiO 3 / 2 ) b (R 1 2SiO 2 / 2 ) c (R 1 3SiO 1 / 2 ) d (R 2 O 1 / 2 ) e (1)

[0013] In formula (1), R 1 each independently represents a hydrogen atom, or an alkyl group, aralkyl group or aryl group having 1 to 8 carbon atoms which may be substituted with a halogen atom.

[0014] R 1The alkyl group having 1 to 8 carbon atoms may be linear, branched, or cyclic, and specific examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, i-butyl, tert-butyl, neopentyl, n-hexyl, cyclohexyl, n-heptyl, and n-octyl groups. An alkyl group having 1 to 3 carbon atoms is preferred, with methyl, ethyl, and propyl being more preferred. The aralkyl group is preferably an aralkyl group having 7 to 20 carbon atoms, and specific examples thereof include benzyl and phenylethyl groups. The aryl group is preferably an aryl group having 6 to 18 carbon atoms, and specific examples thereof include unsubstituted aryl groups such as phenyl and naphthyl groups; and alkylaryl groups having 7 to 18 carbon atoms such as tolyl, xylyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, nonylphenyl, decylphenyl, undecylphenyl, and dodecylphenyl groups. A phenyl group is preferred. In the above formula (1), R 1 Of these, 50 mol % or more are methyl groups, preferably 60 to 100 mol %, and more preferably 80 to 100 mol % are methyl groups. 1 If the proportion of methyl groups is less than 50 mol %, the rubber physical properties of hardness, tensile strength and durability will be poor. If the proportion of methyl groups is less than 100 mol %, the other groups are preferably ethyl, n-propyl, isopropyl and phenyl groups.

[0015] In addition, some or all of the hydrogen atoms of the alkyl group, aralkyl group, and aryl group may be substituted with halogen atoms (fluorine, chlorine, bromine, iodine atoms), and specific examples thereof include a chloromethyl group, a chloropropyl group, a bromoethyl group, a trifluoropropyl group, a chlorophenyl group, and a bromophenyl group.

[0016] In formula (1), R 2 represents a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, or an acetyl group, and among these, a hydrogen atom is preferred. 2At least 20 mol % of the groups are hydrogen atoms, preferably 50 mol % or more are hydrogen atoms, and more preferably 60 mol % or more are hydrogen atoms. a, b, c, and d are numbers that satisfy 0≦a<1, 0<b≦1, 0≦c<1, 0≦d<1, and a+b+c+d=1. In order to improve the rubber physical properties of hardness, tensile characteristics, and durability, it is necessary that 0<b≦1, preferably 0.4≦b≦1, more preferably 0.6≦b≦1, and even more preferably b=1. Furthermore, e is a number that satisfies 0≦e≦2, but in order to improve the rubber physical properties of hardness, tensile characteristics, and durability, it is preferable that 0.05≦e≦1, and more preferably 0.10≦e≦1.

[0017] In the compounding agent for rubber of the present invention, the silicone resin (A) may be a single composition or a mixture of multiple compounds with different compositions.

[0018] Although there are no particular limitations on the weight-average molecular weight of the silicone resin (A) of the present invention, the weight-average molecular weight, calculated as polystyrene equivalent by gel permeation chromatography (GPC), is preferably 500 to 500,000, and more preferably 1,000 to 300,000. If the weight-average molecular weight is less than 500, the hardness and tensile properties may not be improved.

[0019] Furthermore, it is preferable that (A) silicone resin is solid at 25°C. Being solid facilitates mixing into the tire composition. It is preferable that (A) silicone resin has a softening point of 60 to 120°C. The softening point is a value measured by the ring and ball method in accordance with JIS K2207:2006. From the viewpoint of safety during kneading of the rubber composition, it is preferable that (A) silicone resin has a non-volatile content excluding solvents and the like of 95% by mass or more.

[0020] [2] Component (B) In addition to the above-mentioned component (A), the rubber compounding agent of the present invention can use (B), an organosilicon compound having at least one selected from a polysulfide group, a thioester group, and a mercapto group, and an alkoxysilyl group. Component (B) 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.

[0021] 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.

[0022] When the rubber compounding agent of the present invention contains the component (B), the compounding ratio of the component (A) to the component (B) is not particularly limited, but the mass ratio (B) / (A) is preferably 10 / 90 to 95 / 5, and more preferably 30 / 70 to 95 / 5.

[0023] The composition containing the silicone resin (A) of the present invention described above can be used by itself as a compounding agent for rubber, but a mixture of the composition and at least one type of powder may also be used as a compounding agent for rubber.

[0024] Specific examples of powders include carbon black, talc, calcium carbonate, stearic acid, silica, aluminum hydroxide, alumina, magnesium hydroxide, etc. Among these, silica and aluminum hydroxide are preferred from the viewpoint of reinforcing properties, and silica is more preferred.

[0025] When a powder is used, the amount of the powder to be compounded is preferably such that the mass ratio ((X) / (Y)) of the amount of the component (A) or, when the component (B) is included, the total amount (X) of the component (A) and the component (B) to the total amount (Y) of the powder, is 70 / 30 to 5 / 95, taking into consideration the handleability of the rubber compounding agent, transportation costs, and the like.

[0026] The compounding agent for rubber of the present invention may be a mixture with an organic polymer or rubber such as a fatty acid, a fatty acid salt, polyethylene, polypropylene, polyoxyalkylene, polyester, polyurethane, polystyrene, polybutadiene, polyisoprene, natural rubber, or styrene-butadiene copolymer, or may be a mixture with various additives commonly used in tires and other general rubbers such as a vulcanizing agent, a crosslinking agent, a vulcanization accelerator, a crosslinking accelerator, various oils, an antioxidant, a filler, a plasticizer, etc. The form of the compounding agent for rubber may be liquid or solid, and may be further diluted in an organic solvent or emulsified.

[0027] [Rubber Composition] The rubber composition of the present invention comprises the above-described components (A) and (B), an organosilicon compound having an alkoxysilyl group, (C) a diene rubber, and (D) an inorganic filler. The amounts of components (A) and (B) in the rubber composition of the present invention are determined, taking into consideration the physical properties of the resulting rubber and the balance between the degree of effect exerted and economic efficiency, and the like. The amount of component (A) is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, and the amount of component (B) is preferably 1 to 30 parts by mass, more preferably 5 to 20 parts by mass, per 100 parts by mass of component (D), which will be described in detail later.

[0028] [3] Component (C) The diene rubber of component (C) can be any rubber that has been commonly used in various rubber compositions, and specific examples include diene rubbers such as various isoprene rubbers (IR) such as natural rubber, various styrene-butadiene copolymer rubbers (SBR), various polybutadiene rubbers (BR), and acrylonitrile-butadiene copolymer rubbers (NBR), 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) may also be used in combination.

[0029] [4] Component (D) Examples of the inorganic filler of component (D) 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, it is preferable that the rubber composition of the present invention contains silica and carbon black.

[0030] 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.

[0031] The amount of component (D) in the rubber composition of the present invention is preferably 5 to 200 parts by mass, more preferably 10 to 150 parts by mass, and even more preferably 20 to 130 parts by mass, per 100 parts by mass of component (C), from the viewpoints of dispersibility, fuel economy, molding processability, and the like.

[0032] In addition to the components (A) to (D) above, 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.

[0033] 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.

[0034] 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 2.0 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.

[0035] [Rubber Products (Tires)] The rubber composition of the present invention can be used to produce rubber products such as tires by preparing a composition from the above-mentioned components (A) to (D) and other components using a conventional method and vulcanizing or crosslinking the composition. In particular, when producing tires, the rubber composition of the present invention is preferably used in the tread. Tires obtained using the rubber composition of the present invention have reduced rolling resistance and improved wear resistance, thereby achieving the desired fuel economy and excellent durability. The tire structure can be a conventionally known structure, and the manufacturing method can also be a conventionally known manufacturing method. In the case of gas-filled tires, the gas to be filled inside the tire can typically be air, air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium.

[0036] 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.

[0037] Examples 1-1 to 1-6, Comparative Examples 1-1 to 1-5 Using a 4 L internal mixer (MIXTRON, manufactured by Kobe Steel, Ltd.), a natural rubber shown in Table 1 was kneaded for 60 seconds. Next, carbon black, silica, silicone resin, stearic acid, antioxidant, resin, and wax shown in Table 1 were added, the internal temperature was raised to 150°C, and the mixture was discharged. Thereafter, the mixture was stretched using a roll. The obtained rubber composition was again kneaded using an internal mixer (MIXTRON, manufactured by Kobe Steel, Ltd.) until the internal temperature reached 145°C, discharged, and then stretched using a roll. Zinc oxide, vulcanization accelerator, and sulfur shown in Table 1 were added to the mixture and kneaded to obtain a rubber composition.

[0038] Natural rubber: RSS#3 Carbon black: Seest 9H (manufactured by Tokai Carbon Co., Ltd.) Silica: Nipsil AQ (manufactured by Tosoh Silica Co., Ltd.) Sulfide silane: KBE-846 (manufactured by Shin-Etsu Chemical Co., Ltd., bis(triethoxysilylpropyl)tetrasulfide) Silicone resin (A-1): (R 1 SiO 3 / 2 ) 1.00 (R 2 O1 / 2 ) 0.21 and R 1 is a methyl group (100 mol%), and R 2 Silicone resin (A-2): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.12 and R 1 is a methyl group (80 mol%) and a phenyl group (20 mol%), and R 2 Silicone resin (A-3): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.12 and R 1 is a methyl group (80 mol%) and an n-propyl group (20 mol%), and R 2 Silicone resin (A-4): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.12 and R 1 is a methyl group (60 mol%) and a phenyl group (40 mol%), and R 2 Silicone resin (A-5): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.12 and R 1 is a methyl group (40 mol%) and a phenyl group (60 mol%), and R 2Silicone resin (A-6): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.61 and R 1 is a phenyl group (70 mol%) and an n-propyl group (30 mol%), and R 2 Silicone resin (A-7): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.12 and R 1 is an n-propyl group (100 mol%), and R 2 Silicone resin (A-8): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.12 and R 1 is a methyl group (80 mol%) and a phenyl group (20 mol%), and R 2 Silicone resin (A-9): (R 1 SiO 3 / 2 ) 0.80 (R 1 2SiO 2 / 2 ) 0.20 (R 2 O 1 / 2 ) 0.21 and R 1 is a methyl group (100 mol%), and R 2Silicone resin (A-10): (R 1 SiO 3 / 2 ) 0.60 (R 1 2SiO 2 / 2 ) 0.40 (R 2 O 1 / 2 ) 0.21 and R 1 is a methyl group (100 mol%), and R 2 are hydrogen atoms (60 mol%) and methyl groups (40 mol%), and have a weight average molecular weight of 3,000, a softening point of 60°C, and are solid at 25°C. Stearic acid: industrial stearic acid (manufactured by Kao Corporation) Antioxidant: Nocrac 6C (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) Resin: T-REZ RA-100 (manufactured by ENEOS Corporation) 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 DM-P (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) Vulcanization accelerator (b): Noccela CZ-G (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) Sulfur: 5% oil-treated sulfur (manufactured by Hosoi Chemical Industry Co., Ltd.)

[0039] The unvulcanized and vulcanized physical properties of the rubber compositions obtained in Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-5 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 (145°C, 30 minutes) to produce vulcanized rubber sheets.

[0040] [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 1-1 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 1-1 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 300% modulus (M 300 ) [MPa] was measured at room temperature. The results were expressed as an index, with Comparative Example 1-1 being 100. A larger index value indicates a higher modulus and better tensile properties. (4) Dynamic Viscoelasticity (Temperature Dispersion) Measurements were performed using a viscoelasticity measuring device (manufactured by Metrabib) under conditions of a tensile dynamic strain of 1% and a frequency of 55 Hz. 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 tan δ (60°C) value was expressed as an index, with Comparative Example 1-1 being 100. A smaller index value for the tan δ (60°C) value indicates better rolling resistance. (5) Abrasion Resistance Tests were performed using an FPS testing machine (manufactured by Ueshima Seisakusho Co., Ltd.) under conditions of a sample speed of 200 m / min, a load of 20 N, a road surface temperature of 30°C, a slip ratio of 5%, and a slip ratio of 20%. The results obtained were expressed as an index, with Comparative Example 1-1 being 100. A larger index value indicates a smaller amount of wear and better wear resistance. (6) Durability (break time) Using a flexometer (manufactured by Ueshima Seisakusho Co., Ltd.), the test was carried out under conditions of a static load of 60 N, a dynamic displacement of 5.5 mm, a frequency of 45 Hz, and a bath temperature of 100°C. The time until the rubber test piece broke was expressed as an index, with Comparative Example 1-1 being 100. A larger index value indicates a longer time until break and higher durability.

[0041]

[0042] As shown in Table 1, the vulcanized products of the rubber compositions obtained in Examples 1-1 to 1-6 have improved hardness, tensile properties, and durability while maintaining wear resistance, compared to the vulcanized products of the rubber compositions obtained in Comparative Examples 1-1 to 1-5.

[0043] Examples 2-1 to 2-6, Comparative Examples 2-1 to 2-5 Using a 4 L internal mixer (MIXTRON, manufactured by Kobe Steel, Ltd.), SBR and BR listed in Table 2 were kneaded for 30 seconds. Next, the oil components, carbon black, silica, sulfide silane, silicone resin, stearic acid, antioxidant, and wax listed in Table 2 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 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 then stretched using a roll. Zinc oxide, vulcanization accelerator, and sulfur listed in Table 2 were added to the mixture and kneaded to obtain a rubber composition.

[0044] 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., bis(triethoxysilylpropyl)tetrasulfide) Silicone resin (A-1): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.21 and R 1 is a methyl group (100 mol%), and R 2 Silicone resin (A-2): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.12 and R 1is a methyl group (80 mol%) and a phenyl group (20 mol%), and R 2 Silicone resin (A-3): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.12 and R 1 is a methyl group (80 mol%) and an n-propyl group (20 mol%), and R 2 Silicone resin (A-4): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.12 and R 1 is a methyl group (60 mol%) and a phenyl group (40 mol%), and R 2 Silicone resin (A-5): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.12 and R 1 is a methyl group (40 mol%) and a phenyl group (60 mol%), and R 2 Silicone resin (A-6): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.61 and R 1 is a phenyl group (70 mol%) and an n-propyl group (30 mol%), and R 2Silicone resin (A-7): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.12 and R 1 is an n-propyl group (100 mol%), and R 2 Silicone resin (A-8): (R 1 SiO 3 / 2 ) 1.00 (R 2 O 1 / 2 ) 0.12 and R 1 is a methyl group (80 mol%) and a phenyl group (20 mol%), and R 2 Silicone resin (A-9): (R 1 SiO 3 / 2 ) 0.80 (R 1 2SiO 2 / 2 ) 0.20 (R 2 O 1 / 2 ) 0.21 and R 1 is a methyl group (100 mol%), and R 2 Silicone resin (A-10): (R 1 SiO 3 / 2 ) 0.60 (R 1 2SiO 2 / 2 ) 0.40 (R 2 O 1 / 2 ) 0.21 and R 1 is a methyl group (100 mol%), and R 2are hydrogen atoms (60 mol%) and methyl groups (40 mol%), and have a weight average molecular weight of 3,000, a softening point of 60°C, and are solid at 25°C. Stearic acid: industrial stearic acid (manufactured by Kao Corporation) Antioxidant: 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.)

[0045] The unvulcanized and vulcanized physical properties of the rubber compositions obtained in Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-5 were measured by the following methods. The results are also shown in Table 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).

[0046] [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 set to 100. The smaller the index value, the lower the Mooney viscosity and the better the processability. (2) Vulcanization Characteristics (T90) The vulcanization rate at 160°C was measured using a rotorless rheometer, and the minimum torque ML and maximum torque MH were determined from the vulcanization curve, and T90 (the time (minutes) required to reach 90% of the maximum torque value) was calculated. The values ​​were expressed as an index with Comparative Example 2-1 set to 100. The smaller the index value, the faster the vulcanization rate and the better the productivity. [Vulcanized Physical Properties] (3) 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 set to 100. The larger the index value, the higher the hardness and the better the product. (4) 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. 300) [MPa] was measured at room temperature. The results obtained were expressed as an index, with Comparative Example 2-1 being 100. The larger the index value, the higher the modulus and the more excellent the tensile properties. (5) Dynamic viscoelasticity (temperature dispersion) A viscoelasticity measuring device (manufactured by Metrabib) was used, and measurements were taken under conditions of a tensile dynamic strain of 1% and a frequency of 55 Hz. The test specimen was a sheet with a thickness of 0.2 cm and a width of 0.5 cm, with a clamping 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 an index, 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 Co., Ltd.), tests were 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% and a slip ratio of 20%. The results were expressed as an index, with Comparative Example 2-1 set to 100. A larger index value indicates a smaller amount of abrasion and better abrasion resistance. [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 a temperature of 130°C, and expressed as an index, with Comparative Example 2-1 set to 100. A smaller index value indicates a lower Mooney viscosity and better 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 set to 100. The larger the index value, the higher the hardness and the better 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. 300) [MPa] was measured at room temperature. The results obtained were expressed as an index, with Comparative Example 2-1 being 100. The larger the index value, the higher the modulus and the more excellent the tensile properties. (4) Dynamic viscoelasticity (temperature dispersion) A viscoelasticity measuring device (manufactured by Metrabib) was used, and measurements were taken under conditions of a tensile dynamic strain of 1% and a frequency of 55 Hz. The test specimen was a sheet with a thickness of 0.2 cm and a width of 0.5 cm, with a clamping 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 an index, 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. (5) Abrasion Resistance Using an FPS testing machine (manufactured by Ueshima Seisakusho Co., Ltd.), tests were 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% and a slip ratio of 20%. The results obtained were expressed as an index, with Comparative Example 2-1 being 100. A larger index value indicates a smaller amount of wear and better abrasion resistance. (6) Durability (Creep Rate) Using a flexometer (manufactured by Ueshima Seisakusho Co., Ltd.), tests were conducted under conditions of a static load of 60 N, a dynamic displacement of 5.5 mm, a frequency of 45 Hz, and a bath temperature of 100°C. The creep rate (%) after 15 minutes was measured. The results obtained were expressed as an index, with Comparative Example 2-1 being 100. A smaller index value indicates higher durability.

[0047]

[0048] As shown in Table 2, the vulcanized products of the rubber compositions obtained in Examples 2-1 to 2-6 have significantly improved hardness, tensile properties, and durability while maintaining abrasion resistance, compared to the vulcanized products of the rubber compositions obtained in Comparative Examples 2-1 to 2-5.

Claims

1. (A) A compounding agent for diene rubber containing a silicone resin represented by the following formula (1): (SiO 4 / 2 ) a (R 1 SiO 3 / 2 ) b (R 1 2SiO 2 / 2 ) c (R 1 3SiO 1 / 2 ) d (R 2 O 1 / 2 ) e (1) (wherein, R 1 each independently represents a hydrogen atom, or an alkyl group, aralkyl group, or aryl group having 1 to 8 carbon atoms, which may be substituted with a halogen atom; R 1 At least 50 mol % of R are methyl groups, 2 represents a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, or an acetyl group; R 2 at least 20 mol % of the groups are hydrogen atoms, a, b, c, and d are numbers that satisfy 0≦a<1, 0<b≦1, 0≦c<1, 0≦d<1, and a+b+c+d=1, and e is a number that satisfies 0<e≦2.

2. The compounding agent for diene rubber according to claim 1, wherein b is a number satisfying the relationship 0.4≦b≦1.

3. The compounding agent for diene rubber according to claim 2, wherein b is 1.

4. The compounding agent for diene rubber according to claim 1, wherein said silicone resin is solid at 25°C.

5. The compounding agent for diene rubber according to any one of claims 1 to 4, further comprising (B) an organosilicon compound having at least one group selected from the group consisting of a polysulfide group, a thioester group, and a mercapto group, and an alkoxysilyl group.

6. (A) A silicone resin represented by the following formula (1): (SiO 4 / 2 ) a (R 1 SiO 3 / 2 ) b (R 1 2SiO 2 / 2 ) c (R 1 3SiO 1 / 2 ) d (R 2 O 1 / 2 ) e (1) (wherein, R 1 each independently represents a hydrogen atom, or an alkyl group, aralkyl group, or aryl group having 1 to 8 carbon atoms, which may be substituted with a halogen atom; R 1 At least 50 mol % of R are methyl groups, 2 represents a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, or an acetyl group; R 2 (B) an organosilicon compound having an alkoxysilyl group and one or more selected from a polysulfide group, a thioester group, and a mercapto group; (C) a diene-based rubber; and (D) an inorganic filler.

7. A tire formed by molding the rubber composition according to claim 6.

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