Rubber composition for tire, and tire

Abstract

To provide a rubber composition for a tire exhibiting excellent wet grip performance, rolling resistance characteristics and abrasion resistance, and to provide a tire produced by using the composition.SOLUTION: 100 parts by mass of a rubber component containing a specific styrene-butadiene rubber having a styrene content of 25% by mass or less and a glass transition temperature of - 40 °C. or lower, a resin, and 40 to 160 parts by mass of silica, in which a content of the specific styrene-butadiene rubber is 30% by mass or more in the rubber component, the resin is a resin in which a ratio of aromatic hydrocarbon-derived protons obtained by an NMR method is 20% or more, and a styrene content of the specific styrene-butadiene rubber and a parameter S of the resin satisfy (styrene content of specific styrene-butadiene rubber) * (parameter S - 300) ≥ 400, A content of the resin relative to a content of the specific styrene-butadiene rubber is from 1 to 200% by mass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber composition for a tire and a tire. [Background technology]

[0002] BACKGROUND ART Conventionally, rubber compositions for tires that contain petroleum resins in order to control properties such as viscoelasticity have been known (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-002387 Summary of the Invention [Problem to be solved by the invention]

[0004] Recently, from the viewpoints of safety, environmental issues, etc., there has been a demand for a rubber composition that combines high levels of wet grip performance and rolling resistance characteristics, as well as excellent wear resistance. In this context, the present inventors have studied the rubber composition for tires described in Patent Document 1, and have found that the performance of the rubber composition when used in tires may not always be sufficient.

[0005] In view of the above circumstances, the present invention aims to provide a rubber composition for tires that exhibits excellent wet grip performance, rolling resistance characteristics, and abrasion resistance when made into a tire, and a tire manufactured using the rubber composition for tires. [Means for solving the problem]

[0006] As a result of extensive research into the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by blending a specific resin with a specific styrene-butadiene rubber in a predetermined ratio, and have arrived at the present invention. That is, the present inventors have found that the above problems can be solved by the following configuration.

[0007] (1) A rubber composition comprising 100 parts by mass of a rubber component containing a specific styrene-butadiene rubber having a styrene content of 25% by mass or less and a glass transition temperature of −40° C. or less, a resin, and 40 to 160 parts by mass of silica; the content of the specific styrene-butadiene rubber in the rubber component is 30% by mass or more, The resin has a ratio of aromatic hydrocarbon-derived protons of 20% or more as determined by an NMR method, the styrene content of the specific styrene-butadiene rubber and the following parameter S of the resin satisfy the following formula (1), A rubber composition for tires, wherein the content of the resin relative to the content of the specific styrene-butadiene rubber is 1 to 200% by mass.

number

[0008] As will be described below, according to the present invention, it is possible to provide a rubber composition for a tire that exhibits excellent wet grip performance, rolling resistance characteristics and abrasion resistance when made into a tire, and a tire manufactured using the rubber composition for a tire. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a total ion chromatogram obtained by pyrolysis GC-MS of resin A. [Figure 2] 1 is a partial cross-sectional schematic view showing an example of an embodiment of a tire of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The rubber composition for tires and the like of the present invention will be described below. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. Each component may be used alone or in combination of two or more. When two or more components are used in combination, the content of the components refers to the total content unless otherwise specified. The method for producing each component is not particularly limited unless otherwise specified, and may be, for example, a conventionally known method. Furthermore, with regard to a rubber composition for tires, the wet grip performance, rolling resistance characteristics, and abrasion resistance when made into a tire are also simply referred to as "wet grip performance," "rolling resistance characteristics," and "abrasion resistance," respectively. In this specification, "excellent effects of the present invention" may mean that at least one of wet grip performance, rolling resistance characteristics, and abrasion resistance is superior.

[0011] [I] Rubber composition for tires The rubber composition for tires of the present invention (hereinafter also referred to as "the composition of the present invention") is The rubber composition contains 100 parts by mass of a rubber component containing a specific styrene-butadiene rubber having a styrene content of 25% by mass or less and a glass transition temperature of −40° C. or less, a resin, and 40 to 160 parts by mass of silica, the content of the specific styrene-butadiene rubber in the rubber component is 30% by mass or more, The resin has a ratio of aromatic hydrocarbon-derived protons of 20% or more as determined by an NMR method, the styrene content of the specific styrene-butadiene rubber and the following parameter S of the resin satisfy the following formula (1), In the rubber composition for tires, the content of the resin relative to the content of the specific styrene-butadiene rubber is 1 to 200 mass %.

number

[0012] It is believed that the composition of the present invention can solve the above-mentioned problems because of its structure. The reason for this is not clear, but is presumed to be as follows. As described above, the composition of the present invention contains a specific styrene-butadiene rubber (hereinafter also referred to as "specific SBR") and a specific amount of a resin (hereinafter also referred to as "specific resin") having a ratio of aromatic hydrocarbon-derived protons of 20% or more as determined by NMR (nuclear magnetic resonance) method. The specific resin has a structure similar to SBR because the ratio of protons derived from aromatic hydrocarbons (hereinafter also referred to as "aromatic proton ratio") is 20% or more. The specific resin also has a parameter S (hereinafter also referred to as "S value"), which will be described later. Here, the S value is a parameter related to the retention coefficient of peaks (however, peaks with a retention coefficient of 6 or less) and area ratio in a total ion chromatogram (hereinafter also referred to as "TIC") obtained by pyrolysis gas chromatography mass spectrometry (hereinafter also referred to as "pyrolysis GC-MS") using a packing material (structure shown below) similar in structure to SBR, and represents the retention of the monomers that make up the resin to the packing material. Since the specific SBR and the specific resin satisfy the above formula (1), the specific resin is considered to have extremely high compatibility with the specific SBR having a styrene content of 25% by mass or less.

[0013] [ka]

[0014] As a result, in the composition of the present invention, the rubber component containing the specific SBR and the specific resin are compatible to an extremely high degree, which is thought to lead to excellent wet grip performance and rolling resistance characteristics. Furthermore, it is believed that the specific SBR has a predetermined glass transition temperature, and therefore the abrasion resistance of the tire when made into the tire is excellent.

[0015] Each component contained in the composition of the present invention will be described below.

[0016] [1] Rubber component The composition of the present invention contains a rubber component containing a specific styrene-butadiene rubber (specific SBR) having a styrene content of 25% by mass or less and a glass transition temperature of -40°C or less. The rubber component may contain a rubber component other than the specific SBR. The rubber component may be modified with an alkoxy group, an alkoxysilyl group, or the like.

[0017] [Specific SBR] The specific SBR is a copolymer of styrene and butadiene. The specific SBR may be unmodified or modified. Examples of modified specific SBR include SBR modified with an alkoxy group, an alkoxysilyl group, or the like.

[0018] [Styrene content] In the composition of the present invention, the styrene content of the specific SBR is 25% by mass or less. The lower limit of the styrene content of the specific SBR may be more than 0% by mass. The styrene content of the specific SBR is preferably 20% by mass or less, because this provides better effects of the present invention. Here, the styrene content refers to the proportion (% by mass) of repeating units derived from styrene relative to the total SBR.

[0019] [Vinyl unit content] The vinyl unit content of the specific SBR is not particularly limited, but is preferably 20 to 60 mol %, more preferably 20 to 50 mol %, for reasons of better effects of the present invention. Here, the vinyl unit content refers to the proportion (mol %) of repeating units of 1,2-vinyl unit bonds among repeating units derived from butadiene in the SBR.

[0020] [Glass transition temperature] In the composition of the present invention, the glass transition temperature (Tg) of the specific SBR is −40° C. or lower. The glass transition temperature (Tg) of the specific SBR is preferably −85° C. to −50° C., because this provides better effects of the present invention (particularly abrasion resistance). The glass transition temperature can be adjusted, for example, by the styrene content or vinyl unit content. In this specification, the glass transition temperature (Tg) is measured using a differential scanning calorimeter (DSC) at a temperature rise rate of 10° C. / min and calculated by the midpoint method.

[0021] [Content] In the rubber composition of the present invention, the content of the specific styrene-butadiene rubber is 30% by mass or more in the rubber component. The content of the specific SBR in the rubber component is preferably 40% by mass or more, and more preferably 50% by mass or more, because the effects of the present invention are more excellent. The rubber component may be composed of only the specific SBR. Multiple specific SBRs may be used in combination.

[0022] [Other rubber components] The rubber component may contain a rubber component (other rubber component) other than the specific SBR. Examples of such other rubber components include SBR other than the specific SBR, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), and chloroprene rubber (CR). Among these, it is preferable that the other rubber component contains NR or BR, because the effects of the present invention are more excellent.

[0023] [Average Tg] The glass transition temperature of the rubber component as a whole (hereinafter also referred to as "average Tg") is not particularly limited, but in order to achieve better effects of the present invention (particularly abrasion resistance), it is preferably from -100°C to -20°C, and more preferably from -80°C to -20°C. Here, the average Tg of the rubber component is the sum (weighted average value of glass transition temperatures) obtained by multiplying the glass transition temperature (Tg) of each rubber component by the mass fraction of each rubber component.

[0024] [Molecular weight] The weight average molecular weight (Mw) of the rubber component is preferably 100,000 to 10,000,000, and more preferably 300,000 to 3,000,000, for the reason that the effects of the present invention are more excellent. The number average molecular weight (Mn) of the rubber component contained in the composition of the present invention is preferably 50,000 to 5,000,000, and more preferably 150,000 to 1,500,000, for reasons of better effects of the present invention. It is preferable that the Mw and / or Mn of at least one rubber component contained in the rubber component falls within the above range, and it is more preferable that the Mw and / or Mn of all rubber components contained in the rubber component fall within the above range. In this specification, Mw and Mn are values ​​calculated as standard polystyrene obtained by gel permeation chromatography (GPC) measurement under the following conditions. Solvent: Tetrahydrofuran Detector: RI detector

[0025] [2] Specific resin The composition of the present invention contains a resin (specific resin) having a ratio of protons derived from aromatic hydrocarbons (aromatic proton ratio) of 20% or more as determined by NMR.

[0026] [Aromatic proton ratio] In the composition of the present invention, the aromatic proton ratio of the specific resin is 20% or more. The aromatic proton ratio is preferably 22% or more, more preferably 24% or more, even more preferably 26% or more, and particularly preferably 28% or more, because the effects of the present invention are more excellent. There is no particular upper limit to the ratio, but because the effects of the present invention are more excellent, it is preferably 80% or less, and more preferably 50% or less.

[0027] The aromatic proton ratio is determined as follows. Resin is dissolved in a solvent 1 The H-NMR spectrum is measured. In the spectrum, the ratio of the area of ​​the peaks of protons derived from aromatic hydrocarbons (aromatic rings) to the total area of ​​the peaks of protons derived from the resin is calculated, and this is taken as the aromatic proton ratio. For example, when the resin is a styrene polymer (polystyrene), the aromatic proton ratio is the ratio of the peak area of ​​protons derived from benzene rings to the sum of the peak areas of protons derived from polystyrene.

[0028] [S value] The specific resin has the following parameter S (S value).

[0029]

number

[0030] where k n represents the retention coefficient of the nth peak from the smallest retention time in the total ion chromatogram obtained by pyrolysis gas chromatography mass spectrometry of a specific resin, and α represents the retention coefficient of the nth peak from the smallest retention time in the total ion chromatogram obtained by pyrolysis gas chromatography mass spectrometry of a specific resin, and k n represents the n above of the peak with the maximum retention factor of ≦6.0, and A n is k n It represents the ratio (%) of the area of ​​the nth peak to the total area of ​​peaks that satisfy the condition ≦6.0.

[0031] In the composition of the present invention, the specific resin has an S value of 316 or more. In formula (1) described below, when the styrene content of the specific styrene-butadiene rubber is 25% by mass, the S value of the specific resin is 316. Furthermore, since the styrene content of the specific styrene-butadiene rubber in the present invention is 25% by mass or less, it can be derived from the relationship with formula (1) that the S value of the specific resin in the composition of the present invention is 316 or more, as described above. The S value is preferably 320 or more, more preferably 330 or more, and even more preferably 350 or more, because the effects of the present invention are more excellent. There is no particular upper limit to the S value, but the S value is preferably 500 or less, and more preferably 400 or less, because the effects of the present invention are more excellent.

[0032] The pyrolysis gas chromatography mass spectrometry (pyrolysis GC-MS) is carried out under the following conditions.

[0033] (conditions) - Instrument name: Shimadzu GCMS-QP2020 Pyrolysis equipment name: Frontier Labs Double Shot Pyrolyzer PY-2020iD ·Thermal decomposition temperature: 550℃ ·Inlet temperature: 320℃ Column used: 5% diphenyldimethl polysiloxane (GL Sciences UA-5) Column size: Length 30m, inner diameter 0.25mm, film thickness 0.25μm Method (column temperature conditions): 70°C (3 min) → Heat at 10°C / min (25 min) → Final temperature 320°C Carrier gas: Ultra-high purity helium gas (total flow rate: 104 mL / min, column flow rate: 1 mL / min) ·Injection volume: 1μL

[0034] A specific example of how to calculate the S value is shown below. FIG. 1 shows the total ion chromatogram (TIC) of Resin A obtained by pyrolysis GC-MS. Resin A is a resin (aromatic proton ratio: 54%, S value: 236) obtained by thermally polymerizing α-methylstyrene and styrene in a ratio of 6 / 5 (mass ratio). The conditions for pyrolysis GC-MS were as described above. As shown in Figure 1, the TIC of Resin A has two peaks. The retention factor k1 of the peak with the shortest retention time (the left peak) is 1.7, and the retention factor k2 of the peak with the second shortest retention time (the right peak) is 2.8. Since the retention factors of both peaks are 6.0 or less, k n The peak with the largest retention factor that satisfies ≦6.0 is the right peak. Because the right peak is the second peak from the shortest retention time, α in the parameter S is 2. Furthermore, the ratio A1 of the area of ​​the left peak to the sum of the areas of the two peaks is 40(%), and the ratio A2 of the area of ​​the right peak to the sum of the areas of the two peaks is 60(%). Therefore, the S value of Resin A is calculated as 1.7×40+2.8×60=236.

[0035] One example of a method for achieving an S value of 316 or greater is to polymerize a resin using a monomer containing an aromatic hydrocarbon having a polymerizable group, and increase the proportion of components in the aromatic hydrocarbons that have a high retention coefficient (the aforementioned retention coefficient) (preferably components with a retention coefficient of 2 or greater, more preferably components with a retention coefficient of 3 or greater). To enhance the effects of the present invention, the proportion is preferably 50% by mass or greater, more preferably 70% by mass or greater, and even more preferably 90% by mass or greater. The upper limit of the proportion is not particularly limited, and is 100% by mass. Since aliphatic hydrocarbons are likely to decompose at the decomposition temperature (550°C) of the pyrolysis GC-MS described above, the presence of aliphatic hydrocarbons in the monomers that make up the resin is thought to have little effect on the S value.

[0036] [Formula (1)] In the composition of the present invention, the styrene content of the specific styrene-butadiene rubber and the parameter S (S value) of the resin satisfy the following formula (1). Formula (1): (styrene content of specific styrene-butadiene rubber) × (parameter S-300) ≥ 400 In formula (1), the styrene content of the specific styrene-butadiene rubber and the parameter S (S value) of the resin are as described above. The unit of the styrene content of the specific styrene-butadiene rubber is "mass%". It is believed that the composition of the present invention has excellent wet grip performance and rolling resistance properties when the styrene content of the specific styrene-butadiene rubber and the S value of the resin satisfy formula (1). In this specification, "(styrene content of specific styrene-butadiene rubber) x (parameter S-300)" in formula (1) may also be simply referred to as "St amount x (S value - 300)". The lower limit of St amount × (S value − 300) is preferably 500 or more, more preferably 800 or more, and even more preferably 1000 or more, because the effects of the present invention are more excellent. The upper limit of St amount × (S value − 300) is not particularly limited, but is preferably 3000 or less, and more preferably 2000 or less, because the effects of the present invention are more excellent.

[0037] [Preferred embodiment] The monomer constituting the specific resin preferably contains an aromatic hydrocarbon having a polymerizable group (for example, a vinyl group, an isopropenyl group, etc.) because this provides a better effect of the present invention. Specific examples of the aromatic hydrocarbon include styrene, α-methylstyrene, vinyltoluene, isopropenyltoluene, indene, and methylindene. Among these, vinyltoluene, isopropenyltoluene, indene, and methylindene are preferred, and isopropenyltoluene, indene, and methylindene are more preferred, because they provide better effects of the present invention.

[0038] For reasons of better effects of the present invention, the retention coefficient of the aromatic hydrocarbons (the retention coefficient described above) is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. There is no particular upper limit to the retention coefficient, but for reasons of better effects of the present invention, it is preferably 6 or less, and more preferably 5 or less.

[0039] The monomers constituting the specific resin preferably contain aliphatic hydrocarbons (preferably aliphatic hydrocarbons containing unsaturated double bonds) in addition to the above-mentioned aromatic hydrocarbons. The aliphatic hydrocarbon may be linear, branched, or cyclic. Specific examples of the aliphatic hydrocarbons include aliphatic hydrocarbons that constitute C5 fractions, such as isoprene and cyclopentadiene.

[0040] When the monomer constituting the specific resin contains aliphatic hydrocarbons (e.g., C5 fractions) in addition to the aromatic hydrocarbons described above, the content of the aromatic hydrocarbons in the monomer is preferably 30 to 99 mass%, more preferably 50 to 97 mass%, and even more preferably 70 to 95 mass%, for reasons of better effects of the present invention. When the monomer constituting the specific resin contains aliphatic hydrocarbons (e.g., C5 fraction) in addition to the aromatic hydrocarbons described above, the content of the aliphatic hydrocarbons in the monomer is preferably 1 to 70 mass%, more preferably 3 to 50 mass%, and even more preferably 5 to 30 mass%, for reasons of better effects of the present invention.

[0041] [Molecular weight] The weight average molecular weight (Mw) of the specific resin is preferably 100 or more and less than 100,000, more preferably 200 to 50,000, and even more preferably 500 to 10,000, for reasons of better effects of the present invention.

[0042] [Content] In the composition of the present invention, the content of the specific resin relative to the content of the above-mentioned specific SBR (hereinafter also referred to as "specific resin / specific SBR") is 1 to 200% by mass. The specific resin / specific SBR is preferably 2 to 150% by mass, more preferably 3 to 100% by mass, and even more preferably 3 to 40% by mass, because this provides better effects of the present invention.

[0043] In the composition of the present invention, the content of the specific resin is preferably 1 to 200 parts by mass, more preferably 2 to 150 parts by mass, even more preferably 3 to 100 parts by mass, and even more preferably 3 to 40 parts by mass, per 100 parts by mass of the rubber component, because this provides better effects of the present invention.

[0044] [3] Silica The composition of the present invention contains silica. The silica is not particularly limited, and any conventionally known silica can be used. Examples of silica include wet silica, dry silica, fumed silica, and diatomaceous earth. Biomass-derived silica such as rice husks may also be used. The silica may be used alone or in combination of two or more types.

[0045] [CTAB] The cetyltrimethylammonium bromide (CTAB) adsorption specific surface area of ​​silica (hereinafter, "CTAB adsorption specific surface area" may be simply referred to as "CTAB") is not particularly limited, but for the reason that the effect of the present invention is superior, it is preferred that the specific surface area be 70 to 300 m 2 / g, and 100 to 280m 2 / g is more preferred. Here, the CTAB adsorption specific surface area is a value measured in accordance with JIS K6430:2008, Appendix G.

[0046] [Content] In the composition of the present invention, the content of silica is 40 to 160 parts by mass per 100 parts by mass of the rubber component. The content of silica is preferably 50 to 150 parts by mass, more preferably 60 to 140 parts by mass, per 100 parts by mass of the rubber component, for the reason that the effects of the present invention are more excellent.

[0047] [4] Optional component The composition of the present invention may contain components (optional components) other than the above-mentioned components, if necessary. Examples of such components include various additives commonly used in rubber compositions, such as resins other than the specific resin, fillers other than silica (preferably carbon black or aluminum hydroxide), silane coupling agents, oils, thermally expandable microcapsules, zinc oxide (zinc white), stearic acid, antioxidants, waxes, processing aids, liquid polymers, thermosetting resins, vulcanizing agents (e.g., sulfur), vulcanization accelerators (accelerators), and vulcanization activators.

[0048] [Carbon black] The composition of the present invention preferably contains carbon black because the effects of the present invention are more excellent. The carbon black may be used alone or in combination of two or more types. The carbon black is not particularly limited, and various grades such as SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, IISAF-HS, HAF-HS, HAF, HAF-LS, FEF, GPF, and SRF can be used.

[0049] [N2SA] The nitrogen adsorption specific surface area (N2SA) of the carbon black is not particularly limited, but is preferably 50 to 200 m for the reason that the effect of the present invention is more excellent. 2 / g, and 70 to 150m 2 / g is more preferred. Here, the nitrogen adsorption specific surface area (N2SA) is the amount of nitrogen adsorbed onto the surface of carbon black measured according to JIS K6217-2:2001 "Part 2: Determination of specific surface area - Nitrogen adsorption method - Single point method."

[0050] [Content] In the composition of the present invention, the content of carbon black is not particularly limited, but in order to achieve better effects of the present invention, it is preferably 1 to 130 parts by mass, and more preferably 2 to 100 parts by mass, per 100 parts by mass of the rubber component described above.

[0051] [Silane coupling agents] The composition of the present invention preferably contains a silane coupling agent, since this will provide better effects of the present invention.

[0052] The silane coupling agent is not particularly limited as long as it is a silane compound having a hydrolyzable group and an organic functional group. The hydrolyzable group is not particularly limited, and examples thereof include an alkoxy group, a phenoxy group, a carboxyl group, and an alkenyloxy group. Of these, an alkoxy group is preferred because the effects of the present invention are more excellent. When the hydrolyzable group is an alkoxy group, the number of carbon atoms in the alkoxy group is preferably 1 to 16, and more preferably 1 to 4, because the effects of the present invention are more excellent. Examples of alkoxy groups having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, and a propoxy group.

[0053] The organic functional group is not particularly limited, but is preferably a group capable of forming a chemical bond with an organic compound, and examples thereof include an epoxy group, a vinyl group, an acryloyl group, a methacryloyl group, an amino group, a sulfide group, a mercapto group, and a blocked mercapto group (protected mercapto group) (for example, an octanoylthio group). Of these, a sulfide group (particularly a disulfide group or a tetrasulfide group), a mercapto group, and a blocked mercapto group are preferred because they provide better effects of the present invention. The silane coupling agents may be used alone or in combination of two or more.

[0054] The silane coupling agent is preferably a sulfur-containing silane coupling agent, since this provides a better effect of the present invention.

[0055] Specific examples of the above silane coupling agent include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide, triethoxysilylpropyl-methacrylate-monosulfide, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, 3-octanoylthio-1-propyltriethoxysilane, polysiloxane represented by the average composition formula of formula (2) described later, and the like. Among these, one kind may be used alone, or two or more kinds may be used in combination.

[0056] 〔Preferred embodiment〕 The silane coupling agent is preferably a polysiloxane (hereinafter also referred to as "specific polysiloxane") represented by the average composition formula of the following formula (2) because the effects of the present invention are more excellent. (A) a (B) b (C) c (D) d (R 1 ) e SiO (4-2a-b-c-d-e) / 2 (2) In formula (2), A represents a divalent organic group containing a sulfide group. B represents a monovalent hydrocarbon group having 5 to 20 carbon atoms. C represents a hydrolyzable group. D represents an organic group containing a mercapto group. R 1 represents a monovalent hydrocarbon group having 1 to 4 carbon atoms. a to e satisfy the relational expressions of 0 < a < 1, 0 < b < 1, 0 < c < 3, 0 ≦ d < 1, 0 ≦ e < 2, and 0 < 2a + b + c + d + e < 4.)

[0057] 〔Content〕 In the composition of the present invention, the content of the silane coupling agent is not particularly limited, but it is preferably 2 to 20 parts by mass with respect to 100 parts by mass of the rubber component described above because the effects of the present invention are more excellent.

[0058] In addition, in the composition of the present invention, the content of the silane coupling agent relative to the content of silica described above is preferably 1 to 20 mass %, and more preferably 5 to 15 mass %, because this provides better effects of the present invention.

[0059] [5] Method for preparing rubber composition for tires The method for producing the composition of the present invention is not particularly limited, and specific examples thereof include a method of kneading the above-mentioned components using a known method or apparatus (e.g., a Banbury mixer, a kneader, a roll, etc.) When the composition of the present invention contains sulfur or a vulcanization accelerator, it is preferable to first mix the components other than the sulfur and the vulcanization accelerator at a high temperature (preferably 100 to 160°C), cool the mixture, and then mix the sulfur or the vulcanization accelerator. The composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[0060] [II] Tires The tire of the present invention is a tire manufactured using the composition of the present invention described above. The tire of the present invention is preferably a pneumatic tire, and can be filled with air, an inert gas such as nitrogen, or other gases.

[0061] 2 is a partial cross-sectional schematic view of a tire showing one example of an embodiment of the tire of the present invention, although the tire of the present invention is not limited to the embodiment shown in FIG.

[0062] In FIG. 2, reference numeral 1 denotes a bead portion, reference numeral 2 denotes a sidewall portion, and reference numeral 3 denotes a tire tread portion. Between the pair of left and right bead portions 1, a carcass layer 4 with fiber cords embedded therein is mounted, and the ends of this carcass layer 4 are folded back and wrapped around the bead core 5 and bead filler 6 from the inside to the outside of the tire. In the tire tread portion 3, a belt layer 7 is disposed on the outer side of the carcass layer 4 around the entire circumference of the tire. In addition, a rim cushion 8 is disposed in the bead portion 1 at the portion that comes into contact with the rim. At least one of the reference numerals 2 to 3, 5 to 6, and 8 (preferably reference numeral 3) is formed from the composition of the present invention described above.

[0063] The tire of the present invention can be manufactured, for example, by a conventionally known method. The gas to be filled into the tire can be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium. [Example]

[0064] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0065] [Synthesis of SBR] [Production Example 1] Production of modified initiator Two 4 L stainless steel pressure vessels that had been vacuum dried were prepared. 6,922 g of cyclohexane, 85 g of a compound represented by the following formula (3), and 60 g of tetramethylethylenediamine were placed in the first pressure vessel to produce a first reaction solution. [ka] At the same time, 180 g of 2.0 M liquid n-butyllithium and 6,926 g of cyclohexane were charged into a second pressure vessel to produce a second reaction solution. In this case, the molar equivalent ratio of the compound represented by the formula (3), the n-butyllithium, and the tetramethylethylenediamine was 1:1:1. With the pressure in each pressure vessel maintained at 7 bar, the first reaction solution was injected into the continuous reactor through the first continuous channel at a rate of 1.0 g / min, and the second reaction solution was injected into the continuous reactor through the second continuous channel at a rate of 1.0 g / min using a mass flow meter. The temperature of the continuous reactor was maintained at -10°C, the internal pressure was maintained at 3 bar using a backpressure regulator, and the residence time in the reactor was adjusted to within 10 minutes. The reaction was completed, yielding a modified initiator (solution state).

[0066] [Polymerization Example 1] Method for producing specific SBR1 Preparation of polymer in the first reactor and transfer from the first reactor to the second reactor Into the first reactor of a continuous reactor in which three reactors were connected in series, 5.0 kg / h (28.8 mol / h in terms of styrene) of a styrene solution in which 60% by mass of styrene was dissolved in n-hexane, 13.3 kg / h (147.5 mol / h in terms of 1,3-butadiene) of a 1,3-butadiene solution in which 60% by mass of 1,3-butadiene was dissolved in n-hexane, 47.0 kg / h of n-hexane, 40 g / h of a 1,2-butadiene solution in which 2.0% by mass of 1,2-butadiene was dissolved in n-hexane, 50.0 g / h of a solution in which 10% by mass of N,N,N',N'-tetramethylethylenediamine (TMEDA) was dissolved in n-hexane as a polar additive, and the modified initiator prepared in Preparation Example 1 above were continuously injected at a rate of 400.0 g / h. During this, the temperature of the first reactor was maintained at 55°C, and when the polymerization conversion rate reached 41%, the polymer was transferred from the first reactor to the second reactor via a transfer pipe.

[0067] Preparation of polymer in the second reactor and transfer from the second reactor to the third reactor Next, a 1,3-butadiene solution in which 1,3-butadiene was dissolved in n-hexane at a concentration of 60% by mass was injected into the second reactor at a rate of 0.65 kg / h (7.2 mol / h in terms of 1,3-butadiene). During this, the temperature of the second reactor was maintained at 65°C, and when the polymerization conversion rate reached 95% or more, the polymer was transferred from the second reactor to the third reactor via a transfer pipe.

[0068] Modification process Next, a solution of N-(3-(1H-1,2,4-triazol-1-yl)propyl)-3-(trimethoxysilyl)-N-(3-(trimethoxysilyl)propyl)propan-1-amine (structure shown below) dissolved in n-hexane was continuously added to the third reactor [modifier: act.Li (activated lithium) = 1:1 (molar equivalent ratio)]. The temperature of the third reactor was maintained at 65°C. [ka]

[0069] Post-processing Thereafter, a 30% by mass solution of IR1520 (BASF) as an antioxidant was added to the polymerization solution discharged from the third reactor at a rate of 170 g / h and stirred, and TDAE (treated distilled aromatic extract) was added as an extender oil and stirred. The resulting polymer was placed in steam-heated hot water and stirred to remove the solvent, producing a specific SBR1 containing 4.7 parts by mass of TDAE as an extender oil per 100 parts by mass of alkoxysilyl-modified SBR1 (net modified SBR1).

[0070] [Polymerization Example 2] Method for producing specific SBR2 Polymerization was carried out in the same manner as in the preparation of the polymer in the first reactor in the above-mentioned [Polymerization Example 1], except that a styrene solution obtained by dissolving 60% by mass of styrene in n-hexane was introduced into the first reactor at a rate of 7.7 kg / h (44.4 mol / h in terms of styrene), a 1,3-butadiene solution obtained by dissolving 60% by mass of 1,3-butadiene in n-hexane at a rate of 11.5 kg / h (127.6 mol / h in terms of 1,3-butadiene), and a solution obtained by dissolving 10% by mass of N,N,N′,N′-tetramethylethylenediamine (TMEDA) in n-hexane as a polar additive were introduced into the first reactor at a rate of 40.0 g / h, and the polymer was transferred from the first reactor to the second reactor. Next, a 1,3-butadiene solution in which 1,3-butadiene was dissolved in n-hexane at a concentration of 60% by mass was injected into the second reactor at a rate of 0.65 kg / h (7.2 mol / h in terms of 1,3-butadiene). During this, the temperature of the second reactor was maintained at 65°C, and when the polymerization conversion rate reached 95% or more, the polymer was transferred from the second reactor to the third reactor via a transfer pipe. Next, a specific SBR2 containing 20 parts by mass of TDAE as an extender oil for 100 parts by mass of SBR2 modified with alkoxysilyl groups (net modified SBR2) was produced through the same modification step and post-treatment step as in [Polymerization Example 1]. In the modification step, the ratio of modifier:act.Li (activated lithium) was 1:1 (molar equivalent ratio).

[0071] [Polymerization Example 3] Method for producing comparative SBR Polymerization was carried out in the same manner as in the preparation of the polymer in the first reactor in the above-mentioned [Polymerization Example 1], except that a styrene solution obtained by dissolving 60% by mass of styrene in n-hexane was introduced into the first reactor at a rate of 12.1 kg / h (69.7 mol / h in terms of styrene), a 1,3-butadiene solution obtained by dissolving 60% by mass of 1,3-butadiene in n-hexane at a rate of 7.7 kg / h (85.4 mol / h in terms of 1,3-butadiene), and a solution obtained by dissolving 10% by mass of N,N,N',N'-tetramethylethylenediamine (TMEDA) in n-hexane as a polar additive were introduced into the first reactor at a rate of 40.0 g / h, and the polymer was transferred from the first reactor to the second reactor. Next, a 1,3-butadiene solution in which 1,3-butadiene was dissolved in n-hexane at a concentration of 60% by mass was injected into the second reactor at a rate of 2.3 kg / h (25.5 mol / h in terms of 1,3-butadiene). During this, the temperature of the second reactor was maintained at 65°C, and when the polymerization conversion rate reached 95% or more, the polymer was transferred from the second reactor to the third reactor via a transfer pipe. Next, a comparative SBR was produced through the same modification and post-treatment steps as in Polymerization Example 1, containing 16.7 parts by mass of TDAE as an extender oil for 100 parts by mass of alkoxysilyl-modified SBR3 (net modified SBR3). In the modification step, the ratio of modifier to act.Li (activated lithium) was 1:1 (molar equivalent ratio).

[0072] [Production of rubber composition for tires] The components shown in Tables 1 and 2 below were blended in the proportions (parts by mass) shown in the tables. Specifically, first, the components except for sulfur and the vulcanization accelerator were kneaded in a 1.7-liter internal mixer for 5 minutes, and then released when the temperature reached 150°C to obtain a master batch. Next, sulfur and the vulcanization accelerator were kneaded into the obtained master batch using an open roll to obtain a rubber composition for tires. The parts by mass in the SBR column represent the net parts by mass of rubber in the SBR (parts by mass excluding oil-extended oil). When the SBR used in the Examples and Comparative Examples is an oil-extended product containing oil-extended oil, the amount of oil-extended oil derived from the oil-extended product is not shown in Tables 1 and 2, but the oil-extended oil derived from the oil-extended product is contained in each rubber composition for tires produced as described above.

[0073] [Wet grip performance and rolling resistance characteristics] The obtained rubber composition for tires was vulcanized at 170°C for 15 minutes using a mold of a predetermined shape (inner dimensions: length 150 mm, width 150 mm, thickness 2 mm) to prepare a vulcanized rubber sheet. The vulcanized rubber sheets were measured for tan δ at temperatures of 0°C and 60°C under conditions of an elongation deformation strain rate of 10%±2% and a vibration frequency of 20 Hz using a viscoelasticity spectrometer (manufactured by Toyo Seiki Seisakusho, Ltd.) in accordance with JIS K6394:2007. Wet grip performance was evaluated from tan δ at 0°C, and rolling resistance characteristics were evaluated from tan δ at 60°C. The wet grip performance is shown in Tables 1 and 2 as an index (tan δ(0° C.)) with the value of Comparative Example 1 being 100. A larger index means better wet grip performance. In practice, an index of 100 or more is preferable. The rolling resistance properties are shown in Tables 1 and 2 as an index (tan δ(60°C)) with the value of Comparative Example 1 being 100. A smaller index means better rolling resistance properties (smaller rolling resistance). In practice, an index smaller than 100 is preferable.

[0074] [Wear resistance] The resulting rubber composition for tires was vulcanized in a mold of a predetermined shape (inner dimensions: length 15 cm, width 15 cm, thickness 2 mm) at 170°C for 15 minutes to prepare a vulcanized rubber sheet. The abrasion amount of the obtained vulcanized rubber sheet was measured in accordance with JIS K6264-2:2005 using a Lambourn abrasion tester (manufactured by Iwamoto Seisakusho Co., Ltd.) under conditions of a load of 15.0 kg (147.1 N) and a slip ratio of 25%. The abrasion resistance was measured by converting the reciprocal of the abrasion loss in each example and comparative example into an index where the reciprocal of the abrasion loss in Comparative Example 1 was set to 100, and the indexes calculated as above are shown in Tables 1 and 2 (Lambourn). A higher index indicates better abrasion resistance. In practice, an index greater than 100 is preferable.

[0075] [Table 1]

[0076] [Table 2]

[0077] In Tables 1 and 2, the "St content of SBR" and "Tg of SBR" columns indicate the styrene content and glass transition temperature of the SBR (specific SBR1, 2, comparative SBR) used in each example. The value in the "Tg of SBR" column indicates the Tg of the net SBR for each SBR used. In Tables 1 and 2, the columns "aromatic proton ratio of resin" and "S value of resin" indicate the aromatic proton ratio and S value of the resin (resins 1 to 5) used in each example, respectively. In Tables 1 and 2, the column "St amount x (S value - 300)" represents the value calculated by (styrene content of SBR used in each example) x (parameter S-300 of the resin used in each example). In Tables 1 and 2, the column "Resin / SBR" indicates the content (mass %) of resin (Resins 1 to 5) relative to the content of SBR (Specific SBRs 1 and 2, Comparative SBR) in each example.

[0078] 〔resin〕 Details of resins 1 to 5 in Tables 1 and 2 are as follows. Resin 1: A resin obtained by thermal polymerization of C5 fraction, styrene, α-methylstyrene, vinyltoluene, indene, isopropenyltoluene, and methylindene in a mass ratio of 100 / 3 / 4 / 24 / 28 / 9 / 32 (aromatic proton ratio: 25%, S value: 336, Mw: 1936). Resin 2: Resin obtained by thermal polymerization of C5 fraction, indene, and methylindene in a mass ratio of 10 / 63 / 27 (aromatic proton ratio: 41%, S value: 390, Mw: 1037) Resin 3: E1602 manufactured by Synthomer. Partially hydrogenated resin. (Aromatic proton ratio: 15%, S value: 250). Resin 3 has an aromatic proton ratio of less than 20% and an S value of less than 316, so it does not fall under the category of the specific resin defined in the present invention. Resin 4: A resin obtained by thermally polymerizing styrene, α-methylstyrene, vinyltoluene, indene, and isopropenyltoluene in a mass ratio of 3 / 14 / 68 / 13 / 2 (aromatic proton ratio: 37%, S value: 308, Mw: 1522). Note that Resin 4 has an S value of less than 316, and therefore does not qualify as a specific resin in the present invention. Resin 5: Petrotack 90 (C5 / C9 resin) manufactured by Tosoh Corporation (aromatic proton ratio: 29%, S value: 272, Mw: 2000). Note that Resin 5 has an S value of less than 316, and therefore does not qualify as a specific resin in the present invention.

[0079] [Components other than resin] In Tables 1 and 2, the components other than the resin are as follows. Specific SBR1: an oil-extended product of SBR1 modified with an alkoxysilyl group, produced in the above [Polymerization Example 1]. (Styrene content: 16% by mass, vinyl unit content: 25% by mole, Tg: -60°C, weight-average molecular weight: 749,000, number-average molecular weight: 358,000.)

[0080] Specific SBR2: an oil-extended product of alkoxysilyl-modified SBR2 produced in the above Polymerization Example 2. (Styrene content: 25% by mass, vinyl unit content: 20% by mole, Tg: -50°C, weight-average molecular weight: 915,000, number-average molecular weight: 482,000.)

[0081] Comparative SBR: an oil-extended product of alkoxysilyl-modified SBR3 produced in Polymerization Example 3 above. (Styrene content: 39% by mass, vinyl unit content: 26% by mole, Tg: -28°C, weight-average molecular weight: 832,500, number-average molecular weight: 547,000.)

[0082] BR: Butadiene rubber. Nipol BR1220 manufactured by Nippon Zeon Co., Ltd., Tg: -107°C ·Silica: Solvay ZEOSIL 1165MP (CTAB adsorption specific surface area: 160m 2 / g) CB: Carbon black. Vulcan MS manufactured by Cabot Japan. N2SA: 90m2 / g Silane coupling agent 1: Evonik Si69 Silane coupling agent 2: Polysiloxane 1 described in paragraph

[0056] of WO 2014 / 002750 (polysiloxane represented by the following average composition formula, average molecular weight: 860) (corresponding to the specific polysiloxane described above) (-C3H6-S4-C3H6-) 0.083 (-C8H 17 ) 0.667 (-OC2H5) 1.50 (-C3H6SH) 0.167 SiO 0.75 Oil: Shell Lubricants Japan Extract No. 4 S Zinc oxide: Three types of zinc oxide manufactured by Seido Chemical Industry Co., Ltd. Stearic acid: NOF Corporation Beads Stearic Acid YR Anti-aging agent: Flexis 6PPD Sulfur: Tsurumi Chemical Industry Co., Ltd. Kinka-in oil-filled fine powder sulfur Vulcanization accelerator 1: Noccela CZ-G (CZ) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Sumitomo Chemical Co., Ltd., Soxinol DG (DPG)

[0083] [Summary of Tables 1 and 2] As can be seen from Tables 1 and 2, Examples 1 to 5, which contained the specific resin in a predetermined ratio relative to the SBR content, exhibited excellent wet grip performance, rolling resistance characteristics and abrasion resistance. Comparing Examples 1 and 2 (comparison between embodiments differing only in the type of specific resin), Example 2, which had a larger value of St amount × (S value - 300), showed better wet grip performance, rolling resistance characteristics, and wear resistance.

[0084] On the other hand, Comparative Examples 1 to 2 and 7, which contained a resin other than the specific resin and where St amount×(S value−300) did not satisfy formula (1), had insufficient wear resistance. Comparative Examples 1 and 7 also had insufficient wet grip performance and rolling resistance. Comparative Example 2 also had insufficient rolling resistance. Comparative Example 3, which did not contain the specific SBR, had insufficient rolling resistance and wear resistance. Comparative Example 4, in which the specific resin / specific SBR ratio did not fall within the specified range, had insufficient wet grip performance and wear resistance. Comparative Example 5, in which the content of the specific SBR was outside the specified amount, had insufficient wet grip performance and wear resistance. Comparative Example 6, which did not contain silica, had insufficient wet grip performance, rolling resistance and wear resistance. [Explanation of symbols]

[0085] 1 Bead section 2 Sidewall 3 Tire tread 4 carcass layers 5 bead core 6 Bead filler 7 Belt Layer 8 Rim Cushion

Claims

1. The rubber composition contains 100 parts by mass of a rubber component containing a specific styrene-butadiene rubber having a styrene content of 25% by mass or less and a glass transition temperature of −40° C. or less, a resin, and 40 to 160 parts by mass of silica, the content of the specific styrene-butadiene rubber in the rubber component is 30% by mass or more, the resin has a ratio of aromatic hydrocarbon-derived protons determined by an NMR method of 20% or more, the styrene content of the specific styrene-butadiene rubber and the following parameter S of the resin satisfy the following formula (1), The rubber composition for tires, wherein the content of the resin relative to the content of the specific styrene-butadiene rubber is 1 to 200 mass %. [Equation 1] Here, k ｎ represents the retention coefficient of the n-th peak from the shortest retention time in the total ion chromatogram obtained by pyrolysis gas chromatography mass spectrometry of the resin, and α represents the retention coefficient of the n-th peak from the shortest retention time in the total ion chromatogram obtained by pyrolysis gas chromatography mass spectrometry of the resin, and k ｎ represents the n of the peak having the maximum retention factor of ≦6.0, and A ｎ is k ｎ It represents the ratio (%) of the area of ​​the nth peak to the total area of ​​peaks that satisfy the condition ≦6.

0. Formula (1): (styrene content of specific styrene-butadiene rubber)×(parameter S−300)≧400

2. A tire manufactured using the rubber composition for tires according to claim 1.

Images