Tire

Abstract

The present invention provides a tire that is less of a burden on the environment, and also has excellent wear resistance and excellent ozone resistance. This tire is characterized by comprising, in a tread part, outer-layer rubber constituting the tread surface of the tread part, a layer of metal or fiber cords provided inward of the outer-layer rubber in the tire radial direction, and inner-layer rubber positioned between the outer-layer rubber and the layer of metal or fiber cords, wherein: the outer-layer rubber contains a rubber component (A), a resin component (B), a filler (C), and an anti-aging agent (D); the anti-aging agent (D) includes at least one selected from phenylenediamine-based anti-aging agents (D1) represented by a prescribed formula and aminoquinoline-based anti-aging agents (D5) represented by a prescribed formula; and the inner-layer rubber contains a rubber component (A') and an anti-aging agent (D').

Description

tire

[0001] The present invention relates to a tire.

[0002] Tire treads are particularly required to have high abrasion resistance, and performance improvements have been made by optimizing the materials used to manufacture the treads.

[0003] For example, Patent Document 1 discloses a polymer having a relatively high cis content that has been modified with a specific modifier, and a polymer having a nitrogen adsorption specific surface area of ​​100 m ２ It is disclosed that by using a rubber composition in which carbon black exceeding 1000 kJ / g is combined in the tread, a pneumatic tire having both excellent low rolling resistance and excellent wear resistance can be obtained.

[0004] In general, various rubber components constituting tires may deteriorate due to the influence of the external environment, such as in the presence of ozone, and as the deterioration progresses, cracks may occur, etc. To address such problems, rubber compositions containing antioxidants are often used in various rubber components constituting tires.

[0005] For example, Patent Document 2 discloses that cracking and discoloration of the tire surface can be suppressed by applying a rubber composition containing a selected blend of a specific quinoline antioxidant and N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (antiaging agent 6PPD) to the rubber that constitutes the tire surface. Also, in the examples of Patent Document 1, 6PPD is used as the antioxidant.

[0006] JP 2011-219612 A International Publication No. 2018 / 056384

[0007] However, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (antioxidant 6PPD) used in the above-mentioned Patent Documents 1 and 2 may have an impact on the environment. Therefore, it is desirable to use an antioxidant that has a lower environmental impact, taking into account the possibility of future restrictions under European regulations. Conversely, it may be possible to use no or very little antioxidant 6PPD in the rubber that constitutes the tire tread surface. However, the inventors' investigations have revealed that when no or very little antioxidant 6PPD is used, the ozone resistance of the rubber that constitutes the tire tread surface decreases, making it more susceptible to cracking.

[0008] Therefore, an object of the present invention is to provide a tire that has low environmental impact, excellent wear resistance, and excellent ozone resistance.

[0009] That is, the gist of the tire of the present invention that solves the above problems is as follows.

[0010] [1] A tire having a tread portion including an outer layer rubber constituting the tread surface of the tread portion, a layer of metal or fiber cords disposed radially inward of the outer layer rubber, and an inner layer rubber positioned between the outer layer rubber and the layer of metal or fiber cords, wherein the outer layer rubber contains a rubber component (A), a resin component (B), a filler (C), and an antioxidant (D), and the antioxidant (D) is a compound represented by the following general formula (d1): [In the formula, R １０１ and R １０２ are each independently an alkyl group or an aryl group having 7 or more carbon atoms, and R １０１ and R １０２ wherein at least one of the groups is an alkyl group having 7 or more carbon atoms, and a phenylenediamine-based antioxidant (D1) represented by the following general formula (d5): [In the formula, is a single bond or a double bond, R ５０１ and R ５０２ are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a phenyl group; R ５０３ , R ５０４ , R５０５ , R ５０６ , R ５０７ , R ５０８ , R ５０９ and R ５１０ are each independently hydrogen or an alkyl group having 1 to 12 carbon atoms.], and the inner layer rubber contains a rubber component (A') and an antioxidant (D').

[0011] [2] The tire according to [1], wherein the rubber component (A) in the outer layer rubber contains an isoprene-based rubber (A1).

[0012] [3] The tire according to [2], wherein in the outer layer rubber, a mass ratio (B / A1) of the resin component (B) to the isoprene-based rubber (A1) is 0.5 or more, and a mass ratio (D1 / A1) of the phenylenediamine-based antioxidant (D1) to the isoprene-based rubber (A1) is more than 0.025, and a content of the antioxidant (D') in the inner layer rubber is 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component (A').

[0013] [4] The tire according to [2], wherein in the outer layer rubber, the rubber component (A) further contains a styrene-butadiene rubber (A2).

[0014] [5] The tire according to any one of [1] to [4], wherein in the outer layer rubber, the rubber component (A) contains a modified polymer modified with a modifier having a functional group containing a nitrogen atom and an alkoxy group.

[0015] [6] The tire according to [4], wherein the styrene-butadiene rubber (A2) has a glass transition temperature of less than −40° C.

[0016] [7] The tire according to any one of [2] to [4] and [6], wherein the content of the isoprene-based rubber (A1) in the outer layer rubber is 1 to 40 parts by mass per 100 parts by mass of the rubber component (A).

[0017] [8] In the outer layer rubber, the difference in SP value between the isoprene-based rubber (A1) and the resin component (B) is 0.50 (cal / cm３ ) １／２ and the difference in SP value from the styrene-butadiene rubber (A2) is 0.3 (cal / cm ３ ) １／２ The tire according to [4] or [6] above.

[0018] [9] The resin component (B) is a hydrogenated terpene resin, a hydrogenated C ５ based resin, hydrogenated C ５ -C ９ The tire according to any one of [1] to [8], wherein the olefin-based resin is at least one selected from the group consisting of a olefin-based resin and a hydrogenated dicyclopentadiene-based resin.

[0019]

[10] The tire according to any one of [1] to [9], wherein the filler (C) contains recycled carbon black, and the recycled carbon black has an ash content of 20 mass% or less.

[0020]

[11] R in the general formula (d1) １０１ and R １０２ The tire according to any one of [1] to

[10] , wherein the other is a phenyl group.

[0021]

[12] R in the general formula (d1) １０１ and R １０２ At least one of the above has a carbon number of 7 or 8.

[0022]

[13] The tire according to any one of [1] to

[12] , wherein in the outer layer rubber, a mass ratio (B / D) of the resin component (B) to the antioxidant (D) is 2 or more and 40 or less.

[0023]

[14] The tire according to any one of [1] to

[13] , wherein the outer layer rubber contains the antioxidant (D) in an amount of 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component (A), the antioxidant (D) further contains a quinoline-based antioxidant (D2) (excluding the aminoquinoline-based antioxidant (D5) represented by general formula (d5) above), and a proportion of the quinoline-based antioxidant (D2) in the antioxidant (D) is 10% by mass or more and 50% by mass or less.

[0024]

[15] In the outer layer rubber, the antioxidant (D) is further represented by the following general formula (d3): [In the formula, R ３０１ and R ３０２ are each independently a monovalent saturated hydrocarbon group.] (excluding the phenylenediamine-based antioxidant (D1) represented by the general formula (d1) above), and a proportion of the amine-based antioxidant (D3) in the antioxidant (D) is 0.1% by mass or more and 80% by mass or less.

[0025]

[16] In the outer layer rubber, the antioxidant (D) is further represented by the following general formula (d4): [In the formula, R ４０１ and R ４０２ represents a phenyl group, and m4 represents an integer of 7 or greater.], and a proportion of the amine-based antioxidant (D4) in the antioxidant (D) is 0.1% by mass or greater and 80% by mass or less.

[0026] According to the present invention, it is possible to provide a tire that has low environmental impact, excellent wear resistance, and excellent ozone resistance.

[0027] It is a cross-sectional view of a tire of one embodiment of the present invention, a cross-sectional view of a tire of another embodiment of the present invention, and a cross-sectional view of a tire of still another embodiment of the present invention.

[0028] The tire of the present invention will be described in detail below by way of example based on an embodiment thereof.

[0029] The compounds described herein may be derived in part or in whole from fossil sources, biological sources such as plant sources, recycled sources such as used tires, or a mixture of two or more of fossil, biological, and recycled sources.

[0030] In this specification, the term "sustainability rate" refers to the total mass ratio of components derived from biological resources (biomass resources) and components derived from recycled resources (recycled resources) in a target material.

[0031] In this specification, the term "biological resources (biomass resources)" refers to carbon-neutral organic resources derived from living organisms, and includes, for example, materials stored in the form of starch or cellulose, the bodies of animals that grow by eating plants, and products obtained by processing plants or animals, and is a resource excluding fossil resources (petroleum, coal, natural gas, etc.). The biological resources may be edible or non-edible, but are preferably non-edible in order not to compete with food and from the viewpoint of effective resource utilization.

[0032] Specific examples of the biological resources include cellulosic crops (pulp, kenaf, wheat straw, rice straw, waste paper, papermaking residues, etc.), wood, charcoal, compost, food waste, vegetable oil residues, fishery residues, livestock excrement, food waste, wastewater sludge, natural rubber, cotton, oils and fats (palm oil, castor oil, cottonseed oil, soybean oil, linseed oil, rapeseed oil, coconut oil, peanut oil, tall oil, corn oil, rice oil, safflower oil, sesame oil, olive oil, etc.), and the like. Examples of biological resources include: corn oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil, coconut oil, etc.), carbohydrate crops (corn, wheat, rice, rice husks, rice bran, old rice, potatoes, buckwheat, cassava, sago palm, sugarcane, etc.), bagasse (i.e., the residue left after sugarcane juicing), soybeans, soybean pulp refuse, essential oils (pine oil, orange oil, eucalyptus oil, etc.), pulp black liquor, and algae. The biological resources may also be processed (i.e., biological resource-derived substances). Examples of processing methods include biological processing methods utilizing the activity of microorganisms, plants, animals, and their tissue cultures; chemical processing methods utilizing acids, alkalis, catalysts, thermal energy, light energy, etc.; and physical processing methods such as pulverization, compression, microwave treatment, and electromagnetic wave treatment. The biological resources may also be extracted and purified from the biological resources or biological resources that have undergone the above-described processing (i.e., biological resource-derived substances). For example, sugars, proteins, amino acids, fatty acids, fatty acid esters, etc., purified from the above-mentioned biological resources can also be used. Examples of the sugars include sucrose, glucose, trehalose, fructose, lactose, galactose, xylose, allose, talose, gulose, altrose, mannose, idose, arabinose, apiose, maltose, cellulose, starch, chitin, etc., derived from biological resources. Examples of the proteins include compounds derived from biological resources and formed by linking amino acids (preferably L-amino acids), including oligopeptides such as dipeptides. Examples of the amino acids include valine, leucine, isoleucine, arginine, lysine, asparagine, glutamine, phenylalanine, etc., derived from biological resources, with valine, leucine, isoleucine, arginine, and phenylalanine being preferred.The amino acids may be either L-amino acids or D-amino acids, but L-amino acids are preferred from the viewpoints of abundance in nature and ease of availability. Examples of the fatty acids include butyric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, etc., which are derived from biological resources. Examples of the fatty acid esters include modified products of vegetable oils, animal oils, and fats and oils derived from biological resources. These biological resources may contain various materials and impurities.

[0033] In this specification, the term "recycled resources" refers to resources obtained by regenerating (recycling) products that have been used once, or that have been collected without being used, or that have been discarded. For example, recycled resources include resources obtained by regenerating (recycling) used rubber products such as used tires.

[0034] Fig. 1 is a cross-sectional view of a tire according to one embodiment of the present invention. The tire according to this embodiment shown in Fig. 1 has a pair of bead portions 1 and a pair of sidewall portions 2, a tread portion 5 connected to both sidewall portions 2 and having an outer rubber layer 3 and an inner rubber layer 4, in that order from the outer side in the tire radial direction, a carcass 6 extending toroidally between the pair of bead portions 1 to reinforce these portions 1, 2, and 5, and a metal or fiber cord layer 7 disposed radially outward of a crown portion of the carcass 6 and radially inward of the inner rubber layer 4. Here, the outer rubber layer 3 of the tire shown in Fig. 1 is generally also referred to as a "cap rubber," the inner rubber layer 4 of the tire shown in Fig. 1 is generally also referred to as a "base rubber," and the metal or fiber cord layer 7 of the tire shown in Fig. 1 is generally also referred to as a "belt."

[0035] The carcass 6 of the tire shown in FIG. 1 is composed of one carcass ply made of a plurality of parallel-arranged cords covered with a coating rubber, and the carcass 6 is also composed of a main body portion extending in a toroidal shape between the bead cores 8 embedded in the bead portions 1, and turned-up portions wound up radially outward around each bead core 8 from the inner side toward the outer side in the tire width direction, but the number of plies and the structure of the carcass 6 in the tire of the present invention are not limited to this.

[0036] 1 is composed of two belt layers, the number of belt layers constituting the metal or fiber cord layer 7 in the tire of the present invention is not limited to this, and the number of belt layers may be three or more. Here, the belt layer is usually composed of a rubberized layer of metal or fiber cords (preferably steel cords) extending at an angle with respect to the tire equatorial plane, and the two belt layers are laminated so that the metal or fiber cords constituting the belt layers cross each other with the tire equatorial plane in between to constitute the metal or fiber cord layer 7.

[0037] The tire of this embodiment comprises a tread portion 5, an outer rubber layer 3 constituting the tread surface of the tread portion 5, a metal or fiber cord layer 7 disposed radially inward of the outer rubber layer 3, and an inner rubber layer 4 positioned between the outer rubber layer 3 and the metal or fiber cord layer 7. In the tire of this embodiment, the outer rubber layer 3 contains a rubber component (A), a resin component (B), a filler (C), and an antioxidant (D); the antioxidant (D) is represented by the following general formula (d1): [In the formula, R １０１ and R １０２ are each independently an alkyl group or an aryl group having 7 or more carbon atoms, and R １０１ and R １０２ wherein at least one of the groups is an alkyl group having 7 or more carbon atoms, and a phenylenediamine-based antioxidant (D1) represented by the following general formula (d5): [In the formula, is a single bond or a double bond, R ５０１ and R ５０２ are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a phenyl group; R ５０３ , R ５０４ , R ５０５ , R ５０６ , R ５０７ , R ５０８ , R ５０９ and R ５１０are each independently hydrogen or an alkyl group having 1 to 12 carbon atoms.]; and the inner layer rubber 4 contains a rubber component (A') and an antioxidant (D').

[0038] In the tire of this embodiment, the outer layer rubber 3 contains the various components described above, and thus it is possible to improve the wear resistance while maintaining various properties.

[0039] Furthermore, as described above, in the outer layer rubber 3 of the tire of this embodiment, by using the phenylenediamine-based antioxidant (D1) represented by the above general formula (d1) and / or the aminoquinoline-based antioxidant (D5) represented by the above general formula (d5) as a substitute for antioxidants that may have an impact on the environment, it is possible to ensure sufficient ozone resistance and suppress the occurrence of cracks. Moreover, in the tire of this embodiment, since the inner layer rubber 4 contains the antioxidant (D'), the antioxidant (D') migrates to the outer layer rubber 3 over time, thereby further ensuring the ozone resistance of the outer layer rubber 3 and suppressing the occurrence of cracks. Therefore, the tire of this embodiment can have excellent wear resistance and ozone resistance.

[0040] Next, another embodiment of the tire of the present invention will be described by way of example. Figures 2 and 3 are cross-sectional views of another embodiment of the tire of the present invention.

[0041] The tire shown in FIG. 2 has the same structure as the tire shown in FIG. 1 , except that the tread portion 5 includes, in order from the outside in the tire radial direction (in order from the tire surface (tread surface)), an outer layer rubber 3, a base rubber 9, a tread undercushion rubber 10, and a metal or fiber cord layer (belt) 7.

[0042] In the tire shown in Fig. 2, the base rubber 9 and the tread undercushion rubber 10 correspond to the inner layer rubber 4. That is, at least one of the base rubber 9 and the tread undercushion rubber 10 contains an antioxidant (D') in addition to the rubber component (A').

[0043] The tire shown in FIG. 3 has the same structure as the tire shown in FIG. 1 , except that in a tread portion 5, from the outside in the tire radial direction (from the surface (tread surface) of the tire), an outer layer rubber 3, a base rubber 9, a tread undercushion rubber 10, a reinforcing layer (belt reinforcing layer) 11 of a metal or fiber cord layer, and a layer (belt) 7 of a metal or fiber cord.

[0044] The reinforcing layer 11 of the metal or fiber cord layer of the tire shown in FIG. 3 is arranged so as to cover the entire metal or fiber cord layer 7 on the outer side of the metal or fiber cord layer 7 in the tire radial direction, but the reinforcing layer of the metal or fiber cord layer may be arranged so as to cover only both end portions of the metal or fiber cord layer 7 on the outer side of the metal or fiber cord layer 7 in the tire radial direction, or may be a combination of a layer covering the entire metal or fiber cord layer 7 and a pair of layers covering only both end portions of the metal or fiber cord layer 7.

[0045] In the tire shown in Fig. 3, the base rubber 9, the tread undercushion rubber 10, and the reinforcing layer 11 of the metal or fiber cord layer correspond to the inner layer rubber 4. That is, at least one of the base rubber 9, the tread undercushion rubber 10, and the reinforcing layer 11 of the metal or fiber cord layer (coating rubber for the reinforcing cord) contains an antioxidant (D') in addition to the rubber component (A').

[0046] In the tire shown in Figure 3, the reinforcing layer 11 of the metal or fiber cord layer is made of a rubberized layer of reinforcing cords arranged substantially parallel to the tire circumferential direction. The reinforcing layer 11 of the metal or fiber cord layer is formed by continuously spirally winding narrow strips (cord-rubber composites) prepared by rubberizing reinforcing cords with a coating rubber in the tire circumferential direction. In this case, the absence of joints in the tire circumferential direction improves tire uniformity, and the absence of joints also prevents strain concentration at joints. Organic fiber cords such as polyethylene terephthalate cords, nylon cords, and rayon cords can be used as the reinforcing cords of the reinforcing layer 11 of the metal or fiber cord layer.

[0047] The tire of the present invention is not limited to these embodiments. For example, a tire in which the tread undercushion rubber 10 is omitted from the tire shown in FIG. 3 is also a suitable embodiment of the tire of the present invention.

[0048] <Outer Layer Rubber (Rubber Composition for Outer Layer Rubber)> The outer layer rubber of the tire of the present invention can be produced using a rubber composition (rubber composition for outer layer rubber) containing a rubber component (A), a resin component (B), a filler (C), an antioxidant (D), and any other components. Hereinafter, various components that may be contained in the rubber composition for outer layer rubber (hereinafter sometimes simply referred to as the "rubber composition" or the "rubber composition of the present embodiment") will be described.

[0049] (Rubber Component (A)) The rubber composition (rubber composition for outer layer rubber) of this embodiment contains rubber component (A), which provides rubber elasticity to the composition. The rubber component (A) preferably has a sustainability rate of 30% by mass or more, more preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, still more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass.

[0050] The rubber component (A) is preferably a rubber derived from biological resources or a rubber derived from recycled resources. Here, the proportion of the monomer components derived from biological resources in 100 mol% of the monomer components constituting the rubber derived from biological resources is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and may even be 100 mol%. Furthermore, the proportion of the monomer components derived from recycled resources in 100 mol% of the monomer components constituting the rubber derived from recycled resources is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and may even be 100 mol%.

[0051] The rubber component (A) is a component that contributes to crosslinking, and typically has a weight average molecular weight (Mw) of 10,000 or more, preferably 50,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more, and preferably 5,000,000 or less, more preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,300,000 or less. In this specification, the weight average molecular weight (Mw) of the rubber component (A) can be determined in terms of standard polystyrene based on measurements obtained using, for example, a gel permeation chromatograph (GPC) (GPC-8000 series, manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M, manufactured by Tosoh Corporation).

[0052] In the rubber composition of this embodiment, the rubber component (A) preferably contains an isoprene-based rubber (A1). The isoprene-based rubber refers to a rubber containing isoprene-derived units as monomer units and is a type of diene-based rubber. When the rubber component (A) contains the isoprene-based rubber (A1), the breaking strength of the rubber composition can be increased. As a result, the wear resistance of a tire using the rubber composition can be further improved.

[0053] Examples of the isoprene-based rubber (A1) include natural rubber (NR), synthetic isoprene rubber (IR), modified natural rubber (modified NR), modified natural rubber (modified NR), and modified synthetic isoprene rubber (modified IR). Examples of natural rubber (NR) that can be used include those commonly used in the rubber industry for tires, etc., such as RSS#3 and TSR20 (e.g., SIR20 and STR20). The origin of the natural rubber (NR) is not particularly limited, and examples include those derived from Hevea brasiliensis, guayule, and Russian dandelion. Examples of synthetic isoprene rubber (IR) are not particularly limited, and examples include those commonly used in the rubber industry for tires, etc., such as IR2200. Examples of modified NR include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of the modified IR include epoxidized synthetic isoprene rubber, hydrogenated synthetic isoprene rubber, and grafted synthetic isoprene rubber. These isoprene-based rubbers (A1) may be used alone or in combination of two or more. Among these, NR is preferred as the isoprene-based rubber (A1).

[0054] The isoprene-based rubber (A1) preferably has a sustainability ratio of 30% by mass or more, more preferably 40% by mass or more, more preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass. In order to make the sustainability ratio of the isoprene-based rubber (A1) within the above range, it is preferable to use natural rubber (NR) or a polymer synthesized using isoprene derived from biological resources or isoprene derived from recycled resources as a monomer component. In this case, the synthesized polymer may be a homopolymer of a monomer derived from biological resources, a homopolymer of a monomer derived from recycled resources, a copolymer of a monomer derived from biological resources and a monomer derived from recycled resources, or a copolymer of a monomer derived from biological resources and / or a monomer derived from recycled resources and a monomer derived from fossil resources (petroleum, etc.).

[0055] The content of the isoprene-based rubber (A1) is preferably 1 to 80 parts by mass, and more preferably 1 to 40 parts by mass, per 100 parts by mass of the rubber component (A). When the content of the isoprene-based rubber (A1) is 1 to 80 parts by mass per 100 parts by mass of the rubber component (A), the wear resistance of a tire using the rubber composition can be further improved, and wet grip performance can be improved. Furthermore, when the content of the isoprene-based rubber (A1) is 1 to 40 parts by mass per 100 parts by mass of the rubber component (A), the wear resistance of a tire using the rubber composition can be further improved, and wet grip performance can be further improved. Furthermore, from the viewpoint of further increasing the compounding effect of the isoprene-based rubber (A1), the content of the isoprene-based rubber (A1) is more preferably 10 parts by mass or more per 100 parts by mass of the rubber component (A).

[0056] Furthermore, in the rubber composition of this embodiment, the rubber component (A) may contain a butadiene-based rubber. A butadiene-based rubber refers to a rubber containing a unit derived from butadiene as a monomer unit, and is one type of diene-based rubber. Examples of the butadiene-based rubber include butadiene rubber (BR) and aromatic vinyl compound-butadiene copolymer rubber (e.g., styrene-butadiene rubber (SBR)). Here, the butadiene used as a raw material for the butadiene-based rubber is preferably derived from biological resources or recycled resources.

[0057] Examples of the butadiene rubber (BR) include high-cis butadiene rubber, low-cis butadiene rubber, and butadiene rubber containing syndiotactic polybutadiene crystals. The high-cis butadiene rubber preferably has a cis-1,4 bond content of 90% by mass or more. When the rubber component (A) contains butadiene rubber, the content of the butadiene rubber is preferably in the range of 1 to 35 parts by mass per 100 parts by mass of the rubber component.

[0058] As the butadiene rubber (BR), commercially available products can be used, and examples of commercially available butadiene rubbers include products from UBE Elastomers Co., Ltd., ENEOS Materials Corporation, Asahi Kasei Corporation, and Zeon Corporation. These butadiene rubbers may be used alone or in combination of two or more.

[0059] Examples of the aromatic vinyl compound-butadiene copolymer rubber (e.g., SBR) include emulsion-polymerized aromatic vinyl compound-butadiene copolymer rubber (e.g., emulsion-polymerized styrene-butadiene rubber (E-SBR)) and solution-polymerized aromatic vinyl compound-butadiene copolymer rubber (e.g., solution-polymerized styrene-butadiene rubber (S-SBR)). In the aromatic vinyl compound-butadiene copolymer rubber, examples of the aromatic vinyl compound (aromatic vinyl monomer) include styrene, vinylnaphthalene, and divinylnaphthalene. These aromatic vinyl compounds may be used alone or in combination of two or more. Among these, styrene is preferred, and styrene derived from biological resources and styrene derived from recycled resources are particularly preferred. That is, SBR is preferred as the aromatic vinyl compound-butadiene copolymer rubber. The styrene may have a substituent. As the aromatic vinyl compound-butadiene copolymer rubber, commercially available products can be used, and examples of such commercially available products include products from Asahi Kasei Corporation, ENEOS Materials Corporation, Zeon Corporation, Sumitomo Chemical Co., Ltd. These aromatic vinyl compound-butadiene copolymer rubbers may be used alone or in combination of two or more.

[0060] The butadiene-based rubber preferably has a sustainability rate of 30% by mass or more, more preferably 40% by mass or more, more preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass. To achieve a sustainability rate within the above range, for example, a polymer synthesized using a bioresource-derived butadiene, a recycled resource-derived butadiene, a bioresource-derived aromatic vinyl compound (e.g., bioresource-derived styrene), or a recycled resource-derived aromatic vinyl compound (e.g., recycled resource-derived styrene) as a monomer component may be used. In this case, the synthesized polymer may be a homopolymer of a bioresource-derived monomer, a homopolymer of a recycled resource-derived monomer, a copolymer of a bioresource-derived monomer and a recycled resource-derived monomer, or a copolymer of a bioresource-derived monomer and / or a recycled resource-derived monomer and a fossil resource (e.g., petroleum)-derived monomer. Note that the butadiene rubber (B-BR) derived from biological resources (biomass resources) and aromatic vinyl compound-butadiene copolymer rubber derived from biological resources (for example, styrene-butadiene rubber (B-SBR) derived from biological resources (biomass resources)) include not only rubber obtained by polymerizing butadiene or the like according to conventional methods, but also rubber obtained by reactions involving microorganisms, plants, animals, and tissue cultures thereof (hereinafter also referred to as "microorganisms, etc.") or enzymatic reactions.

[0061] In order to set the sustainability rate of the entire rubber component (A) within the above range, it is preferable to use natural rubber (NR) as the rubber component (A) as described above, or to use a polymer synthesized using a monomer component derived from a biological resource or a monomer component derived from a recycled resource as a monomer component.

[0062] Generally, the raw materials for rubber compositions for tires (e.g., rubber and its monomers, fillers, resins, etc.) require large-scale manufacturing equipment for their production, and are therefore typically produced in large factories in specific regions, requiring significant amounts of energy for the storage and transportation of raw materials and products. In contrast, materials derived from biological resources (biomass resources) are derived from local agricultural products, forests, etc., and can be produced on a small scale through microbial fermentation and catalytic reactions. By utilizing local products and waste, the energy required for transporting and storing raw materials can be reduced, and the energy required for transporting and storing the produced materials to tire factories can also be reduced, making them environmentally friendly. Materials derived from recycled resources can be obtained, for example, by dismantling and pyrolyzing used tires to extract the tire-constituting materials, such as rubber, fillers, and steel cords. In addition, sulfur can be obtained from biological resources or processed products of biological resources by a method including a desulfurization step of desulfurizing biological resources or processed products of biological resources to remove sulfur-containing substances from the biological resources or processed products of biological resources, a recovery step of recovering sulfur from the desulfurization residue generated in the desulfurization step, and a processing step of processing the recovered sulfur into sulfur for vulcanization (for example, the method described in Japanese Patent Application No. 2022-140390), and raw materials for tire rubber compositions can be obtained from various waste products and used items. In this way, the use of sustainable materials (materials derived from biological resources or materials derived from recycled resources) can reduce the overall environmental impact of tire manufacturing, such as reducing carbon dioxide emissions (LCCO2) over the entire life cycle, reducing energy consumption (LCE) over the entire life cycle, reducing costs incurred over the entire life cycle (LCC), and reducing the use of fossil resources.

[0063] Furthermore, when producing the rubber composition, the ratios of monomer components derived from biological resources, monomer components derived from recycled resources, and monomer components derived from fossil resources can be appropriately selected depending on the supply situation of biological resources, recycled resources, and fossil resources (e.g., monomer components derived from fossil resources) and / or market demand (e.g., demand for biological resources as food). By polymerizing the monomer components derived from biological resources, monomer components derived from recycled resources, and monomer components derived from fossil resources, rubber derived from sustainable materials (materials derived from biological resources or materials derived from recycled resources) can be obtained that has performance equivalent to that of conventional synthetic rubber. When using monomer components derived from recycled resources, it may be difficult to separate them from monomer components derived from fossil resources due to the manufacturing process of the monomers. In such cases, the environmental impact can be evaluated by adopting the mass balance approach.

[0064] The ratio of each monomer unit (e.g., a unit derived from isoprene, a unit derived from butadiene, or a unit derived from an aromatic vinyl compound) in the entire rubber component (A) can be adjusted as needed. The ratio of each monomer unit in the entire rubber component (A) can be adjusted, for example, by appropriately combining the above-mentioned isoprene-based rubber (A1) and butadiene-based rubber. The ratio of cis-bond units in the butadiene-derived units can also be adjusted as needed. In this specification, the term "monomer unit" refers to a structural unit of a polymer, the term "isoprene-derived unit" refers to a structural unit in a polymer based on the isoprene monomer (including isoprene units in natural rubber), the term "butadiene-derived unit" refers to a structural unit in a polymer based on the butadiene monomer, and the term "aromatic vinyl compound-derived unit" refers to a structural unit in a polymer based on the aromatic vinyl compound monomer. In this specification, the ratio of each monomer unit is measured by NMR.

[0065] The rubber component (A) may contain diene rubbers such as acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR), in addition to the above-mentioned isoprene-based rubber (A1), butadiene rubber (BR), and aromatic vinyl compound-butadiene copolymer rubber (e.g., SBR). The rubber component (A) may also contain halogenated butyl rubber, ethylene-propylene rubber (EPR, EPDM), fluororubber, silicone rubber, and urethane rubber. These rubber components may be used alone or in combination of two or more. Among these, diene rubbers such as butadiene rubber (BR) and chloroprene rubber (CR) are preferred, with butadiene rubber (BR) being more preferred.

[0066] The rubber component (A) may be modified to have a functional group that interacts with fillers such as carbon black and silica. Examples of such functional groups include amino groups, amide groups, isocyanate groups, imino groups, imidazole groups, urea groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxyl groups, nitrile groups, pyridyl groups, alkoxy groups, hydroxyl groups, oxy groups, epoxy groups, ether groups, carbonyl groups, oxycarbonyl groups, silyl groups, alkoxysilyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, and thiocarbonyl groups. These functional groups may have a substituent. These functional groups may be introduced into the rubber component either individually or in combination. Among these, an amino group, an alkoxy group, and an alkoxysilyl group are preferred, and a substituted amino group in which a hydrogen atom of an amino group is substituted with an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and an alkoxysilyl group having 1 to 6 carbon atoms are more preferred.

[0067] The functional group can be introduced, for example, by reacting a compound (modifier) ​​having the functional group with the rubber component. The functional group is a modified functional group that has interactivity with fillers such as silica and carbon black, and examples thereof include nitrogen-containing functional groups, silicon-containing functional groups, and oxygen-containing functional groups. Examples of compounds (modifiers) having nitrogen-containing functional groups include amino group-containing compounds, and examples of compounds (modifiers) having silicon-containing functional groups include silicon halides and hydrocarbyloxysilane compounds. Examples of compounds (modifiers) having oxygen-containing functional groups include alkoxy group-containing compounds, alkylene oxide group-containing compounds, and trialkylsilyloxy group-containing compounds. More specifically, examples of the compounds described in WO 2016 / 194316 and WO 2019 / 117256 include the compounds described in WO 2016 / 194316 and WO 2019 / 117256. These modifiers may be used alone or in combination of two or more.

[0068] The rubber derived from sustainable materials (materials derived from biological resources or materials derived from recycled resources) can be produced in the same manner as conventional methods for producing synthetic rubber derived from fossil resources, for example, by using monomer components derived from biological resources or monomer components derived from recycled resources, and, if necessary, monomer components derived from fossil resources. Furthermore, the rubber derived from sustainable materials (particularly rubber derived from biological resources) can also be obtained by reactions using microorganisms or enzyme reactions.

[0069] Regarding the method for preparing bioresource-derived rubber from the above-mentioned bioresources, for example, the method described in JP 2022-179158 A can be used. For example, by using butadiene obtained from a bioresource as the monomer component, it is possible to obtain a bioresource (biomass resource)-derived butadiene rubber (B-BR). Furthermore, by using styrene obtained from a bioresource and butadiene obtained from a bioresource as the monomer components, it is possible to obtain a bioresource (biomass resource)-derived styrene-butadiene rubber (B-SBR). Here, methods for obtaining B-BR and B-SBR from bioresources include artificial polymerization methods, in vivo polymerization methods, and polymerization methods using biological enzymes. The molecular weight, branching, microstructure, etc. of the obtained B-BR and B-SBR can be appropriately adjusted by changing the polymerization conditions according to known methods depending on the performance of the target tire.

[0070] Suitable butadienes obtained from biological resources include butadienes derived from alkyl alcohols (preferably ethanol and butanol, more preferably butanol), butadienes derived from alkenes (preferably ethylene), and butadienes derived from unsaturated carboxylic acids (preferably tiglic acid). Two or more of these butadienes may be used in combination. Suitable styrenes obtained from biological resources include styrenes obtained from plants (preferably plants belonging to the Hamamelidaceae, Styraxaceae, and Apocynaceae families, more preferably plants belonging to the Liquidambar, Styrax, and Catharanthus roseus, and even more preferably sweetgum, Styrax rostrata, and Catharanthus roseus), and styrenes obtained from microorganisms (preferably microorganisms belonging to the Penicillium and Escherichia genera, more preferably P. citrinum, and transformed E. coli). Suitable styrenes may be used in combination.

[0071] Recently, biomass industrial complexes centered on bioethanol, bioethylene, and the like have been planned. However, bioethanol and bioethylene are produced primarily using sugars and / or cellulose as biological resources, and do not effectively utilize other biological resources such as proteins, lipids, and amino acids. Furthermore, sugars compete with food, and excessive use of cellulose leads to deforestation. Therefore, depending on the supply status of various biological resources, the supply status of renewable resources, the supply status of fossil resources, and market demands (e.g., demand for biomass resources as food), it is preferable to use multiple types of monomer components derived from biological resources as the biological resource-derived monomer component, or to use a combination of monomer components derived from biological resources, monomer components derived from renewable resources, and monomer components derived from fossil resources, and further to appropriately adjust the ratios of these monomer components. This allows for the effective utilization of a wide range of biological resources, such as sugars, proteins, and lipids, as well as renewable resources, without relying on a single type of biological resource. It also allows for a stable supply of rubber derived from sustainable materials and further allows for environmental considerations depending on the production conditions. When multiple types of monomer components derived from biological resources are used, it is preferable to use monomer components derived from different biological resources, i.e., monomer components obtained from different biological resources. Specifically, it is preferable to use a mixture of butadienes derived from multiple types of biological resources with different origins as the biological resource-derived butadiene, and / or to use a mixture of styrenes derived from multiple types of biological resources with different origins as the biological resource-derived styrene. This allows for effective use of multiple types of biological resources.

[0072] In the rubber composition of this embodiment, it is preferable that the rubber component (A) further contains a styrene-butadiene rubber (SBR) (A2), which is a butadiene-based rubber. By blending the styrene-butadiene rubber (A2) in addition to the above-mentioned isoprene-based rubber (A1) as the rubber component (A), the dispersibility of the filler (C) can be improved, and the wear resistance of a tire to which the rubber composition is applied can be further improved. Furthermore, it is preferable that the styrene-butadiene rubber (A2) has a glass transition temperature of less than -40°C. In this case, the wear resistance of a tire to which the rubber composition is applied can be further improved.

[0073] From the viewpoint of further improving abrasion resistance, the glass transition temperature of the styrene-butadiene rubber (A2) is more preferably −45° C. or lower, still more preferably −50° C. or lower, and is preferably higher than −90° C. In addition, styrene-butadiene rubber having a glass transition temperature higher than −90° C. is easy to synthesize.

[0074] The content of the styrene-butadiene rubber (A2) is preferably 20 to 99 parts by mass, more preferably 30 to 99 parts by mass, more preferably 40 to 99 parts by mass, more preferably 50 to 99 parts by mass, and even more preferably 60 to 99 parts by mass, per 100 parts by mass of the rubber component (A). When the content of the styrene-butadiene rubber (A2) is 60 to 99 parts by mass per 100 parts by mass of the rubber component (A), the wear resistance of a tire to which the rubber composition is applied can be further improved, and wet grip performance can also be improved.

[0075] The difference in SP value between the styrene-butadiene rubber (A2) and the isoprene-based rubber (A1) is 0.3 (cal / cm ３ ) １／２ It is preferable that the calorie content is 0.35 (cal / cm ３ ) １／２ It is more preferable that the difference in SP value between the styrene-butadiene rubber (A2) and the isoprene-based rubber (A1) is 0.3 (cal / cm ３ ) １／２In the above cases, the styrene-butadiene rubber (A2) and the isoprene-based rubber (A1) tend to become incompatible with each other.

[0076] The styrene-butadiene rubber (A2) preferably has a bound styrene content of less than 15% by mass. The bound styrene content of the styrene-butadiene rubber (A2) refers to the proportion of styrene units contained in the styrene-butadiene rubber. When the bound styrene content of the styrene-butadiene rubber (A2) is less than 15% by mass, the glass transition temperature is likely to be low. The bound styrene content of the styrene-butadiene rubber (A2) is more preferably 14% by mass or less, more preferably 13% by mass or less, and even more preferably 12% by mass or less. Furthermore, from the viewpoint of the abrasion resistance of a tire to which the rubber composition is applied, the bound styrene content of the styrene-butadiene rubber (A2) is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 8% by mass or more. The bound styrene content of the styrene-butadiene rubber (A2) can be adjusted by the amount of monomers used in the polymerization for synthesizing the styrene-butadiene rubber (A2), the degree of polymerization, etc.

[0077] The rubber component (A) preferably contains a modified polymer modified with a modifier having a nitrogen-containing functional group and an alkoxy group. By blending the modified polymer modified with a modifier having a nitrogen-containing functional group and an alkoxy group, the wear resistance of a tire using the rubber composition can be further improved.

[0078] The modifying agent having a nitrogen atom-containing functional group and an alkoxy group is a general term for a modifying agent having at least one nitrogen atom-containing functional group and at least one alkoxy group. The nitrogen atom-containing functional group is preferably selected from the following: The functional group is a monovalent hydrocarbon group having 1 to 30 carbon atoms and containing a straight-chain, branched, alicyclic, or aromatic ring, and having a functional group selected from the group consisting of a primary amino group, a primary amino group protected with a hydrolyzable protecting group, an onium salt residue of a primary amine, an isocyanate group, a thioisocyanate group, an imine group, an imine residue, an amide group, a secondary amino group protected with a hydrolyzable protecting group, a cyclic secondary amino group, an onium salt residue of a cyclic secondary amine, an acyclic secondary amino group, an onium salt residue of an acyclic secondary amine, an isocyanuric acid triester residue, a cyclic tertiary amino group, an acyclic tertiary amino group, a nitrile group, a pyridine residue, an onium salt residue of a cyclic tertiary amine, and an onium salt residue of an acyclic tertiary amine, or a monovalent hydrocarbon group having 1 to 30 carbon atoms and containing a straight-chain, branched, alicyclic, or aromatic ring, which may contain at least one heteroatom selected from an oxygen atom, a sulfur atom, and a phosphorus atom.

[0079] The modified polymer is not particularly limited and may be any of the rubbers described above modified with the modifier. However, the modified polymer is preferably a modified styrene-butadiene rubber, i.e., a modified styrene-butadiene rubber (modified SBR). In other words, the styrene-butadiene rubber (A2) preferably contains modified SBR. In this case, the wear resistance of a tire using the rubber composition can be further improved.

[0080] A preferred embodiment of the modified polymer will be explained below by taking modified styrene-butadiene rubber (modified SBR) as an example.

[0081] -Modified polymer of first preferred embodiment- The modified polymer is preferably a styrene-butadiene rubber (SBR) modified with an aminoalkoxysilane compound, and more preferably has its terminals modified with an aminoalkoxysilane compound from the viewpoint of having a high affinity for the filler (C). When the terminals of the styrene-butadiene rubber are modified with an aminoalkoxysilane compound, the interaction between the modified styrene-butadiene rubber and the filler (C) (particularly silica) becomes particularly strong.

[0082] The modified site of the styrene-butadiene rubber may be the molecular terminal as described above, or may be the main chain. Styrene-butadiene rubber having a molecular terminal modified can be produced, for example, by reacting various modifiers with the terminal of a styrene-butadiene copolymer (unmodified styrene-butadiene rubber) having an active terminal, according to the methods described in WO 2003 / 046020 and JP 2007-217562 A. In a preferred embodiment, the styrene-butadiene rubber having a molecular terminal modified can be produced, according to the methods described in WO 2003 / 046020 and JP 2007-217562 A, by reacting an aminoalkoxysilane compound with the terminal of a styrene-butadiene copolymer having an active terminal with a cis-1,4 bond content of 75% or more, and then reacting the resulting mixture with a carboxylic acid partial ester of a polyhydric alcohol for stabilization.

[0083] The carboxylic acid partial ester of a polyhydric alcohol refers to an ester of a polyhydric alcohol and a carboxylic acid, which has one or more hydroxyl groups. Specifically, esters of fatty acids with sugars or modified sugars having 4 or more carbon atoms are preferably used. More preferred examples of this ester include (1) fatty acid partial esters of polyhydric alcohols, particularly partial esters (monoesters, diesters, or triesters) of saturated or unsaturated higher fatty acids having 10 to 20 carbon atoms with polyhydric alcohols, and (2) ester compounds in which 1 to 3 partial esters of polycarboxylic acids and higher alcohols are bonded to a polyhydric alcohol. Polyhydric alcohols used as raw materials for the partial esters are preferably sugars (whether hydrogenated or unhydrogenated) having 5 or 6 carbon atoms and at least three hydroxyl groups, glycols, polyhydroxy compounds, and the like. Furthermore, the raw fatty acids are preferably saturated or unsaturated fatty acids having 10 to 20 carbon atoms, such as stearic acid, lauric acid, and palmitic acid. Among the fatty acid partial esters of polyhydric alcohols, sorbitan fatty acid esters are preferred, and specific examples include sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, and sorbitan trioleate.

[0084] The aminoalkoxysilane compound is not particularly limited, but is preferably an aminoalkoxysilane compound represented by the following general formula (i): １１ ａ -Si-(OR １２ ) ４－ａ ... (i)

[0085] In general formula (i), R １１ and R １２ each independently represents a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms; R １１ and R １２ At least one of the groups is substituted with an amino group, a is an integer of 0 to 2, and OR １２If there are multiple, each OR １２ may be the same or different, and the molecule does not contain any active protons.

[0086] The aminoalkoxysilane compound is also preferably an aminoalkoxysilane compound represented by the following general formula (ii):

[0087]

[0088] In the general formula (ii), n1+n2+n3+n4=4 (wherein n2 is an integer of 1 to 4, and n1, n3, and n4 are integers of 0 to 3). １ is at least one functional group selected from a saturated cyclic tertiary amine compound residue, an unsaturated cyclic tertiary amine compound residue, a ketimine residue, a nitrile group, a (thio)isocyanate group, an isocyanuric acid trihydrocarbyl ester group, a nitrile group, a pyridine group, a (thio)ketone group, an amide group, and a primary or secondary amino group having a hydrolyzable group. １ may be the same or different, and A １ may be a divalent group that bonds with Si to form a cyclic structure. ２１ represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when n1 is 2 or more, they may be the same or different. ２２ is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, both of which may contain a nitrogen atom and / or a silicon atom. ２２ may be the same or different, or may be joined together to form a ring. ２３ represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a halogen atom, and when n3 is 2 or greater, may be the same or different. ２４represents a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and may be the same or different when n4 is 2 or greater. As the hydrolyzable group in the primary or secondary amino group having a hydrolyzable group, a trimethylsilyl group or a tert-butyldimethylsilyl group is preferred, and a trimethylsilyl group is particularly preferred.

[0089] The aminoalkoxysilane compound represented by the above general formula (ii) is preferably an aminoalkoxysilane compound represented by the following general formula (iii).

[0090]

[0091] In the general formula (iii), p1+p2+p3=2 (wherein p2 is an integer of 1 to 2, and p1 and p3 are integers of 0 to 1). ２ is NRa (Ra is a monovalent hydrocarbon group, a hydrolyzable group, or a nitrogen-containing organic group). ２５ is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ２６ is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a nitrogen-containing organic group, any of which may contain a nitrogen atom and / or a silicon atom. ２６ may be the same or different, or may be joined together to form a ring. ２７ R is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a halogen atom. ２８ is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. As the hydrolyzable group, a trimethylsilyl group or a tert-butyldimethylsilyl group is preferred, and a trimethylsilyl group is particularly preferred.

[0092] The aminoalkoxysilane compound represented by the above general formula (ii) is also preferably an aminoalkoxysilane compound represented by the following general formula (iv) or (v).

[0093]

[0094] In the general formula (iv), q1+q2=3 (wherein q1 is an integer of 0 to 2, and q2 is an integer of 1 to 3). ３１ is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ３２ and R ３３ are each independently a hydrolyzable group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ３４ are monovalent aliphatic or alicyclic hydrocarbon groups having 1 to 20 carbon atoms or monovalent aromatic hydrocarbon groups having 6 to 18 carbon atoms, and when q1 is 2, they may be the same or different. ３５ represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when q2 is 2 or more, may be the same or different.

[0095]

[0096] In the general formula (v), r1+r2=3 (where r1 is an integer of 1 to 3, and r2 is an integer of 0 to 2). ３６ is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ３７ represents a dimethylaminomethyl group, a dimethylaminoethyl group, a diethylaminomethyl group, a diethylaminoethyl group, a methylsilyl(methyl)aminomethyl group, a methylsilyl(methyl)aminoethyl group, a methylsilyl(ethyl)aminomethyl group, a methylsilyl(ethyl)aminoethyl group, a dimethylsilylaminomethyl group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when r1 is 2 or more, they may be the same or different. R３８ represents a hydrocarbyloxy group having 1 to 20 carbon atoms, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and may be the same or different when r2 is 2. A specific example of the aminoalkoxysilane compound represented by general formula (v) is N-(1,3-dimethylbutylidene)-3-triethoxysilyl-1-propanamine.

[0097] The aminoalkoxysilane compound represented by the above general formula (ii) is also preferably an aminoalkoxysilane compound represented by the following general formula (vi) or (vii):

[0098]

[0099] In general formula (vi), R ４０ is a trimethylsilyl group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ４１ R is a hydrocarbyloxy group having 1 to 20 carbon atoms, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ４２ is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, where TMS represents a trimethylsilyl group (the same applies hereinafter).

[0100]

[0101] In general formula (vii), R ４３ and R ４４ are each independently a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ４５ is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and each R ４５ may be the same or different.

[0102] The aminoalkoxysilane compound represented by the above general formula (ii) is also preferably an aminoalkoxysilane compound represented by the following general formula (viii) or the following general formula (ix).

[0103]

[0104] In general formula (viii), s1+s2 is 3 (wherein s1 is an integer of 0 to 2, and s2 is an integer of 1 to 3). ４６ is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ４７ and R ４８ are each independently a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ４７ or R ４８ may be the same or different.

[0105]

[0106] In general formula (ix), X is a halogen atom. ４９ is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ５０ and R ５１ are each independently a hydrolyzable group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or R ５０ and R ５１ are bonded to form a divalent organic group. ５２ and R ５３ are each independently a halogen atom, a hydrocarbyloxy group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ５０ and R ５１ As the hydrolyzable group, a hydrolyzable group is preferred, and as the hydrolyzable group, a trimethylsilyl group or a tert-butyldimethylsilyl group is preferred, and a trimethylsilyl group is particularly preferred.

[0107] The aminoalkoxysilane compound represented by the above general formula (ii) is also preferably an aminoalkoxysilane compound represented by the following general formula (x), the following general formula (xi), the following general formula (xii), or the following general formula (xiii).

[0108]

[0109]

[0110]

[0111]

[0112] In the general formulas (x) to (xiii), the symbols U and V are each an integer of 0 to 2 and satisfy U+V=2. ５４ ~ ９２ may be the same or different and are monovalent or divalent aliphatic or alicyclic hydrocarbon groups having 1 to 20 carbon atoms, or monovalent or divalent aromatic hydrocarbon groups having 6 to 18 carbon atoms. α and β in general formula (xiii) are integers of 0 to 5.

[0113] Among the compounds satisfying general formula (x), general formula (xi), and general formula (xii), N1,N1,N7,N7-tetramethyl-4-((trimethoxysilyl)methyl)heptane-1,7-diamine, 2-((hexyl-dimethoxysilyl)methyl)-N1,N1,N3,N3-2-pentamethylpropane-1,3-diamine, N1-(3-(dimethylamino)propyl)-N3,N3-dimethyl-N1-(3-(trimethoxysilyl)propyl)propane-1,3-diamine, and 4-(3-(dimethylamino)propyl)-N1,N1,N7,N7-tetramethyl-4-((trimethoxysilyl)methyl)heptane-1,7-diamine are particularly preferred. Among the compounds satisfying general formula (xiii), N,N-dimethyl-2-(3-(dimethoxymethylsilyl)propoxy)ethanamine, N,N-bis(trimethylsilyl)-2-(3-(trimethoxysilyl)propoxy)ethanamine, N,N-dimethyl-2-(3-(trimethoxysilyl)propoxy)ethanamine, and N,N-dimethyl-3-(3-(trimethoxysilyl)propoxy)propan-1-amine are particularly preferred.

[0114] -Modified polymer according to a second preferred embodiment- The modified polymer is also preferably a styrene-butadiene rubber (SBR) modified with a coupling agent represented by the following general formula (I). In this case, the wear resistance of a tire using the rubber composition can be further improved.

[0115]

[0116] In the above general formula (I), R １ , R ２ and R ３ R each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms. ４ , R ５ , R ６ , R ７ and R ９ R each independently represents an alkyl group having 1 to 20 carbon atoms. ８ and R １１ R each independently represents an alkylene group having 1 to 20 carbon atoms. １０represents an alkyl group or a trialkylsilyl group having 1 to 20 carbon atoms, m represents an integer of 1 to 3, and p represents 1 or 2. R １ ~R １１ When a plurality of i, j, and p are present, they are each independent. i, j, and k each independently represent an integer of 0 to 6, provided that (i + j + k) is an integer of 3 to 10. A represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom, and a phosphorus atom, and having no active hydrogen. Here, in general formula (I), the hydrocarbon group represented by A includes saturated, unsaturated, aliphatic, and aromatic hydrocarbon groups. Examples of organic groups having no active hydrogen include a hydroxyl group (-OH), a secondary amino group (>NH), a primary amino group (-NH ２ ), a functional group having an active hydrogen such as a sulfhydryl group (-SH), or an organic group not having such a functional group.

[0117] The styrene-butadiene rubber modified with the coupling agent represented by the general formula (I) has a weight average molecular weight (Mw) of 20×10 ４ ~300 x 10 ４ and the molecular weight is 200 × 10 relative to the total amount of the modified styrene-butadiene rubber. ４ ~500 x 10 ４ It is preferable that the modified styrene-butadiene rubber contains 0.25 to 30 mass % of the modified styrene-butadiene rubber represented by the formula (I) and has a shrinkage factor (g') of less than 0.64.

[0118] In general, polymers having branches tend to have smaller molecular size compared to linear polymers having the same absolute molecular weight, and the shrinkage factor (g') is an index of the ratio of the molecular size to that of a linear polymer having the same assumed absolute molecular weight. In other words, the shrinkage factor (g') tends to decrease as the degree of branching of a polymer increases. In this embodiment, intrinsic viscosity is used as an index of molecular size, and linear polymers have an intrinsic viscosity [η] = -3.883 M ０．７７１ The shrinkage factor (g') for each absolute molecular weight of the modified styrene-butadiene rubber is calculated, and the shrinkage factor (g') is used as the value that follows the relational expression below. ４~200 x 10 ４ The average value of the contraction factor (g') when the above formula is used is the contraction factor (g') of the modified styrene-butadiene rubber. Here, "branching" refers to a branch formed by direct or indirect bonding of one polymer to another polymer. Furthermore, the "degree of branching" refers to the number of polymers that are directly or indirectly bonded to one branch. For example, when five styrene-butadiene copolymer chains (described below) are indirectly bonded to each other via coupling residues (described below), the degree of branching is 5. Note that the coupling residue is a structural unit of the modified styrene-butadiene rubber that is bonded to the styrene-butadiene copolymer chain, and is, for example, a structural unit derived from a coupling agent that is generated by reacting a styrene-butadiene copolymer (described below) with a coupling agent. Furthermore, the styrene-butadiene copolymer chain is a structural unit of the modified styrene-butadiene rubber, and is, for example, a structural unit derived from a styrene-butadiene copolymer that is generated by reacting a styrene-butadiene copolymer (described below) with a coupling agent. The shrinkage factor (g') is preferably less than 0.64, more preferably 0.63 or less, more preferably 0.60 or less, even more preferably 0.59 or less, and even more preferably 0.57 or less. The lower limit of the shrinkage factor (g') is not particularly limited and may be below the detection limit, but is preferably 0.30 or more, more preferably 0.33 or more, even more preferably 0.35 or more, and even more preferably 0.45 or more. By using a modified styrene-butadiene rubber having a shrinkage factor (g') within this range, the processability of the rubber composition is improved. Since the shrinkage factor (g') tends to depend on the degree of branching, the shrinkage factor (g') can be controlled, for example, using the degree of branching as an index. Specifically, when a modified styrene-butadiene rubber has a branching degree of 6, its shrinkage factor (g') tends to be 0.59 or more and 0.63 or less, and when a modified styrene-butadiene rubber has a branching degree of 8, its shrinkage factor (g') tends to be 0.45 or more and 0.59 or less.

[0119] The styrene-butadiene rubber modified with the coupling agent represented by the general formula (I) preferably has branches and a degree of branching of 5 or more. Furthermore, the modified styrene-butadiene rubber has one or more coupling residues and a styrene-butadiene copolymer chain bonded to the coupling residue, and more preferably, the branches include branches in which five or more styrene-butadiene copolymer chains are bonded to one coupling residue. By specifying the structure of the modified styrene-butadiene rubber so that the degree of branching is 5 or more and the branches include branches in which five or more styrene-butadiene copolymer chains are bonded to one coupling residue, the contraction factor (g') can be more reliably reduced to less than 0.64. The number of styrene-butadiene copolymer chains bonded to one coupling residue can be confirmed from the value of the contraction factor (g'). Furthermore, the modified styrene-butadiene rubber more preferably has branches and a degree of branching of 6 or more. Furthermore, it is more preferable that the modified styrene-butadiene rubber has one or more coupling residues and a styrene-butadiene copolymer chain bonded to the coupling residue, and further, that the branching includes branches in which six or more styrene-butadiene copolymer chains are bonded to one coupling residue. By specifying the structure of the modified styrene-butadiene rubber so that the branching degree is 6 or more and the branching includes branches in which six or more styrene-butadiene copolymer chains are bonded to one coupling residue, the shrinkage factor (g') can be made 0.63 or less. Furthermore, it is more preferable that the modified styrene-butadiene rubber has branches, and the branching degree is 7 or more, and even more preferably 8 or more. The upper limit of the branching degree is not particularly limited, but it is preferably 18 or less.Furthermore, the modified styrene-butadiene rubber has one or more coupling residues and styrene-butadiene copolymer chains bonded to the coupling residues, and further, it is more preferable that the branches include branches in which seven or more styrene-butadiene copolymer chains are bonded to one coupling residue, and it is particularly preferable that the branches include branches in which eight or more styrene-butadiene copolymer chains are bonded to one coupling residue. By specifying the structure of the modified styrene-butadiene rubber so that the branching degree is 8 or more and the branches include branches in which eight or more styrene-butadiene copolymer chains are bonded to one coupling residue, the shrinkage factor (g') can be made 0.59 or less.

[0120] It is preferable that at least one end of the styrene-butadiene copolymer chain is bonded to a silicon atom of each coupling residue. In this case, the ends of a plurality of styrene-butadiene copolymer chains may be bonded to one silicon atom. Alternatively, an end of the styrene-butadiene copolymer chain and an alkoxy group or hydroxyl group having 1 to 20 carbon atoms may be bonded to one silicon atom, and as a result, that one silicon atom may constitute an alkoxysilyl group or silanol group having 1 to 20 carbon atoms.

[0121] The modified styrene-butadiene rubber may be an oil-extended rubber obtained by adding an extender oil. The modified styrene-butadiene rubber may be either non-oil-extended or oil-extended, but from the viewpoint of abrasion resistance, the Mooney viscosity measured at 100°C is preferably 20 or more and 100 or less, and more preferably 30 or more and 80 or less.

[0122] The weight average molecular weight (Mw) of the modified styrene-butadiene rubber is preferably 20×10 ４ 300 x 10 or more ４ or less, more preferably 50×10 ４ or more, more preferably 64×10 ４ More preferably, it is 80×10 ４ The weight average molecular weight is preferably 250×10 ４or less, and more preferably 180×10 ４ or less, and more preferably 150×10 ４ The weight average molecular weight is 20×10 or less. ４ When the weight average molecular weight is 300×10 or more, the low loss property and abrasion resistance of the rubber composition can be sufficiently improved. ４ When it is equal to or less than this, the processability of the rubber composition is improved.

[0123] The modified styrene-butadiene rubber has a molecular weight of 200×10 relative to the total amount (100% by mass) of the modified styrene-butadiene rubber. ４ Above 500 x 10 ４ It is preferable that the modified styrene-butadiene rubber (hereinafter also referred to as "specific high molecular weight component") contains 0.25% by mass or more and 30% by mass or less. When the content of the specific high molecular weight component is 0.25% by mass or more and 30% by mass or less, the low loss and abrasion resistance of the rubber composition can be sufficiently improved. The modified styrene-butadiene rubber contains the specific high molecular weight component preferably at 1.0% by mass or more, more preferably at 1.4% by mass or more, even more preferably at 1.75% by mass or more, even more preferably at 2.0% by mass or more, particularly preferably at 2.15% by mass or more, and extremely preferably at 2.5% by mass or more. Furthermore, the modified styrene-butadiene rubber contains the specific high molecular weight component preferably at 28% by mass or less, more preferably at 25% by mass or less, even more preferably at 20% by mass or less, and even more preferably at 18% by mass or less. In this specification, the "molecular weight" of the rubber component refers to the molecular weight in terms of standard polystyrene obtained by GPC (gel permeation chromatography). In order to obtain a modified styrene-butadiene rubber having a content of a specific high molecular weight component within this range, it is preferable to control the reaction conditions in the polymerization step and the reaction step described below. For example, in the polymerization step, the amount of an organomonolithium compound used as a polymerization initiator, described below, may be adjusted. Furthermore, in the polymerization step, whether the polymerization is performed in a continuous or batchwise manner, it is preferable to use a method having a residence time distribution, i.e., to widen the time distribution of the propagation reaction.

[0124] In the modified styrene-butadiene rubber, the molecular weight distribution (Mw / Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 1.6 to 3.0. If the molecular weight distribution of the modified styrene-butadiene rubber is in this range, the processability of the rubber composition will be good.

[0125] The method for producing the modified styrene-butadiene rubber is not particularly limited, but preferably includes a polymerization step of copolymerizing butadiene and styrene using an organic monolithium compound as a polymerization initiator to obtain a styrene-butadiene copolymer (unmodified styrene-butadiene rubber), and a reaction step of reacting an active terminal of the styrene-butadiene copolymer with a pentafunctional or higher reactive compound (hereinafter also referred to as a "coupling agent").

[0126] The polymerization step is preferably a propagation polymerization by a living anionic polymerization reaction, which can produce a styrene-butadiene copolymer having active terminals and a modified styrene-butadiene rubber with a high modification rate. The styrene-butadiene copolymer is obtained by copolymerizing 1,3-butadiene and styrene.

[0127] The amount of the organic monolithium compound used as a polymerization initiator is preferably determined based on the molecular weight of the target styrene-butadiene copolymer or modified styrene-butadiene rubber. The amount of monomers, such as 1,3-butadiene and styrene, used relative to the amount of polymerization initiator is related to the degree of polymerization, i.e., the number average molecular weight and / or weight average molecular weight. Therefore, to increase the molecular weight, it is advisable to adjust the amount of polymerization initiator to a smaller amount, and to decrease the molecular weight, it is advisable to adjust the amount of polymerization initiator to a larger amount. The organic monolithium compound is preferably an alkyllithium compound from the viewpoints of industrial availability and ease of control of the polymerization reaction. In this case, a styrene-butadiene copolymer having an alkyl group at the polymerization initiation terminal is obtained. Examples of alkyllithium compounds include n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium. As the alkyllithium compound, n-butyllithium and sec-butyllithium are preferred from the viewpoints of industrial availability and ease of control of the polymerization reaction. These organic monolithium compounds may be used alone or in combination of two or more.

[0128] In the polymerization step, examples of the polymerization reaction mode include batch and continuous polymerization modes. In a continuous mode, one or two or more connected reactors can be used. Continuous reactors, for example, tank-type or tubular reactors equipped with a stirrer, are used. In a continuous mode, preferably, monomers, an inert solvent, and a polymerization initiator are continuously fed into the reactor, a polymer solution containing a polymer is obtained in the reactor, and the polymer solution is continuously discharged. Batch reactors, for example, tank-type reactors equipped with a stirrer, are used. In a batch mode, preferably, monomers, an inert solvent, and a polymerization initiator are fed, and if necessary, monomers are added continuously or intermittently during polymerization, a polymer solution containing a polymer is obtained in the reactor, and the polymer solution is discharged after the polymerization is completed. In this embodiment, in order to obtain a styrene-butadiene copolymer having a high proportion of active ends, a continuous mode is preferred, which allows the polymer to be continuously discharged and subjected to the next reaction in a short period of time.

[0129] The polymerization step is preferably carried out in an inert solvent. Examples of the solvent include hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific hydrocarbon solvents include, but are not limited to, aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene, and hydrocarbons consisting of mixtures thereof. Treating impurities such as allenes and acetylenes with an organometallic compound before subjecting the mixture to the polymerization reaction tends to produce a styrene-butadiene copolymer having a high concentration of active terminals, and thus tends to produce a modified styrene-butadiene rubber with a high modification rate, which is preferable.

[0130] A polar compound may be added in the polymerization step. Adding a polar compound allows styrene to be randomly copolymerized with 1,3-butadiene, and the polar compound also tends to be useful as a vinylating agent for controlling the microstructure of the 1,3-butadiene moiety. Examples of the polar compound include ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, and 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxide compounds such as potassium tert-amylate, potassium tert-butylate, sodium tert-butylate, and sodium tert-amylate; and phosphine compounds such as triphenylphosphine. These polar compounds may be used alone or in combination of two or more.

[0131] In the polymerization step, from the viewpoint of productivity, the polymerization temperature is preferably 0° C. or higher, more preferably 120° C. or lower, and particularly preferably 50° C. or higher and 100° C. or lower. When the temperature is within such a range, it tends to be possible to ensure a sufficient amount of the coupling agent to react with the active terminals after the completion of polymerization.

[0132] The amount of bound butadiene in the styrene-butadiene copolymer or modified styrene-butadiene rubber is not particularly limited, but is preferably 40% by mass or more and 100% by mass or less, and more preferably 55% by mass or more and 80% by mass or less. The amount of bound styrene in the styrene-butadiene copolymer or modified styrene-butadiene rubber is not particularly limited, but is preferably more than 0% by mass or less and 60% by mass or less, and more preferably 20% by mass or more and 45% by mass or less. When the amount of bound butadiene and the amount of bound styrene are within the above ranges, the low loss and abrasion resistance of the rubber composition can be further improved. The amount of bound styrene can be measured by ultraviolet absorption of phenyl groups, and the amount of bound butadiene can also be determined from this.

[0133] In the styrene-butadiene copolymer or modified styrene-butadiene rubber, the amount of vinyl bonds in the butadiene bond units is not particularly limited, but is preferably 10 mol% or more and 75 mol% or less, and more preferably 20 mol% or more and 65 mol% or less. When the amount of vinyl bonds is within the above range, the low loss and abrasion resistance of the rubber composition can be further improved. For modified styrene-butadiene rubber, the amount of vinyl bonds (1,2-bond amount) in the butadiene bond units can be determined by Hampton's method [R. R. Hampton, Analytical Chemistry, 21, 923 (1949)].

[0134] The alkoxysilyl group possessed by the coupling agent represented by the general formula (I) above tends to react with, for example, the active terminal possessed by the styrene-butadiene copolymer, dissociating the alkoxylithium and forming a bond between the terminal of the styrene-butadiene copolymer chain and the silicon of the coupling residue. The number of alkoxysilyl groups possessed by the coupling residue is the value obtained by subtracting the number of SiOR groups subtracted by the reaction from the total number of SiOR groups possessed by one molecule of the coupling agent. Furthermore, the azasilacycle group possessed by the coupling agent forms an >N-Li bond and a bond between the terminal of the styrene-butadiene copolymer and the silicon of the coupling residue. Note that the >N-Li bond tends to easily become >NH and LiOH upon exposure to water, etc. during finishing. Furthermore, any alkoxysilyl groups remaining unreacted in the coupling agent tend to easily become silanols (Si-OH groups) upon exposure to water, etc. during finishing.

[0135] The reaction temperature in the reaction step is preferably the same as the polymerization temperature of the styrene-butadiene copolymer, more preferably 0°C or higher and 120°C or lower, and even more preferably 50°C or higher and 100°C or lower. The temperature change from the end of the polymerization step to the addition of the coupling agent is preferably 10°C or lower, more preferably 5°C or lower. The reaction time in the reaction step is preferably 10 seconds or longer, more preferably 30 seconds or longer. From the viewpoint of the coupling rate, the shorter the time from the end of the polymerization step to the start of the reaction step, the more preferably it is within 5 minutes. Mixing in the reaction step may be performed by mechanical stirring, stirring with a static mixer, or the like. When the polymerization step is continuous, the reaction step is also preferably continuous. For example, a tank-type or tubular reactor equipped with a stirrer is used in the reaction step. The coupling agent may be diluted with an inert solvent and continuously supplied to the reactor. When the polymerization step is batchwise, the reaction step may be performed by either adding the coupling agent to the polymerization reactor or transferring it to a separate reactor.

[0136] In the general formula (I), A is preferably represented by any one of the following general formulas (II) to (V): When A is represented by any one of the general formulas (II) to (V), a modified styrene-butadiene rubber having better performance can be obtained.

[0137] In the general formula (II), B １ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. １ are each independent of each other.

[0138] In the general formula (III), B ２ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, B ３ represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ２ and B ３ are each independent of each other.

[0139] In the general formula (IV), B ４ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ４ are each independent of each other.

[0140] In the general formula (V), B ５ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ５ are each independent of each other.

[0141] B in the general formulas (II) to (V) １ , B ２ , B ４ , B ５ Regarding the above, examples of the hydrocarbon group having 1 to 20 carbon atoms include an alkylene group having 1 to 20 carbon atoms.

[0142] Preferably, in the general formula (I), A is represented by the general formula (II) or (III), and k is 0. More preferably, in the general formula (I), A is represented by the general formula (II) or (III), and k is 0, and in the general formula (II) or (III), a is an integer of 2 to 10. Even more preferably, in the general formula (I), A is represented by the general formula (II), and k is 0, and in the general formula (II), a is an integer of 2 to 10. Examples of such coupling agents include bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, and tetrakis(3-trimethoxysilylpropyl). bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trismethoxysilylpropyl)methyl-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trismethoxysilylpropyl)-methyl-1,3-propanediamine, and the like are particularly preferred among these.

[0143] The amount of the compound represented by general formula (I) added as the coupling agent can be adjusted so that the moles of styrene-butadiene copolymer to the moles of coupling agent react in a desired stoichiometric ratio, which tends to achieve a desired degree of branching. Specifically, the moles of the polymerization initiator are preferably 5.0 times or more, more preferably 6.0 times or more, relative to the moles of the coupling agent. In this case, in general formula (I), the number of functional groups of the coupling agent ((m-1) x i + p x j + k) is preferably an integer of 5 to 10, and more preferably an integer of 6 to 10.

[0144] In order to obtain a modified styrene-butadiene rubber having the specific polymer component, the molecular weight distribution (Mw / Mn) of the styrene-butadiene copolymer is preferably 1.5 or more and 2.5 or less, more preferably 1.8 or more and 2.2 or less. The obtained modified styrene-butadiene rubber is preferably one in which a single peak is detected in the molecular weight curve by GPC. The peak molecular weight of the modified styrene-butadiene rubber by GPC is Mp １ , the peak molecular weight of the styrene-butadiene copolymer is Mp ２ In this case, it is preferable that the following formula is satisfied: １ / Mp ２ )<1.8×10-12×(Mp ２ -120 x 10 ４ ) ２ +2 MP ２ is 20 x 10 ４ Above 80 x 10 ４ Below, Mp １ is 30 x 10 ４ Above 150 x 10 ４ The following is more preferred:

[0145] The modification rate of the modified styrene-butadiene rubber is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more. When the modification rate is 30% by mass or more, the low loss property and abrasion resistance of the rubber composition can be further improved.

[0146] After the reaction step, a deactivator, neutralizer, or the like may be added to the copolymer solution as needed. Examples of deactivators include, but are not limited to, water; alcohols such as methanol, ethanol, and isopropanol; and neutralizers include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture having 9 to 11 carbon atoms, with the majority having 10 carbon atoms); aqueous solutions of inorganic acids; and carbon dioxide gas. Furthermore, from the viewpoint of preventing gel formation after polymerization and improving stability during processing, it is preferable to add an antioxidant such as 2,6-di-tert-butyl-4-hydroxytoluene (BHT), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol)propionate, or 2-methyl-4,6-bis[(octylthio)methyl]phenol to the modified styrene-butadiene rubber.

[0147] The modified styrene-butadiene rubber can be obtained from the polymer solution by any known method, including, for example, a method in which the solvent is separated by steam stripping or the like, the polymer is filtered, and then the polymer is dehydrated and dried to obtain the polymer, a method in which the polymer is concentrated in a flashing tank and then devolatilized using a vent extruder or the like, and a method in which the polymer is directly devolatilized using a drum dryer or the like.

[0148] The modified styrene-butadiene rubber obtained by reacting the coupling agent represented by the above general formula (I) with a styrene-butadiene copolymer is represented, for example, by the following general formula (VI).

[0149]

[0150] In the general formula (VI), D represents a styrene-butadiene copolymer chain, and the weight average molecular weight of the styrene-butadiene copolymer chain is 10 × 10 ４ ~100 x 10 ４The styrene-butadiene copolymer chain is a structural unit of a modified styrene-butadiene rubber, and is, for example, a structural unit derived from a styrene-butadiene copolymer, which is generated by reacting a styrene-butadiene copolymer with a coupling agent. １２ , R １３ and R １４ R each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms. １５ and R １８ R each independently represents an alkyl group having 1 to 20 carbon atoms. １６ , R １９ , and R ２０ R each independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. １７ and R ２１ R each independently represents an alkylene group having 1 to 20 carbon atoms. ２２ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. m and x represent integers of 1 to 3, with x≦m, p represents 1 or 2, y represents an integer of 1 to 3, with y≦(p+1), and z represents an integer of 1 or 2. When there are multiple D and R, １２ ~R ２２ , m, p, x, y, and z are each independent and may be the same or different. Furthermore, i represents an integer of 0 to 6, j represents an integer of 0 to 6, k represents an integer of 0 to 6, (i + j + k) is an integer of 3 to 10, and ((x × i) + (y × j) + (z × k)) is an integer of 5 to 30. A represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom, and a phosphorus atom, and having no active hydrogen. The hydrocarbon group represented by A includes saturated, unsaturated, aliphatic, and aromatic hydrocarbon groups. Examples of the organic group having no active hydrogen include a hydroxyl group (—OH), a secondary amino group (>NH), a primary amino group (—NH ２ ), a functional group having an active hydrogen such as a sulfhydryl group (-SH), or an organic group not having such a functional group.

[0151] In the general formula (VI), A is preferably represented by any one of the general formulas (II) to (V). When A is represented by any one of the general formulas (II) to (V), the low loss property and abrasion resistance of the rubber composition can be further improved.

[0152] -Third Preferred Embodiment of Modified Polymer- It is also preferable that the modified polymer is a styrene-butadiene rubber (SBR) in which at least one end is modified with a modifying agent containing a compound (alkoxysilane) represented by the following general formula (1):

[0153]

[0154] By using, as the rubber component, a styrene-butadiene rubber modified with a modifier containing a compound represented by the general formula (1) containing an oligosiloxane, which is a filler affinity functional group, and a tertiary amino group, the dispersibility of fillers such as silica can be improved. As a result, the rubber composition of the present invention has improved filler dispersibility, which greatly improves low loss properties and further improves the wear resistance of tires to which the rubber composition is applied.

[0155] In the above general formula (1), R １ ~R ８ are each independently an alkyl group having 1 to 20 carbon atoms; L １ and L ２ are each independently an alkylene group having 1 to 20 carbon atoms; and n is an integer of 2 to 4.

[0156] Specifically, in formula (1), R １ ~R ４ may each independently represent a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, １ ~R ４When substituted, each independently may be substituted with one or more substituents selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkoxy group having 4 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, an alkanoyloxy group having 2 to 12 carbon atoms (Ra-COO-, where Ra is an alkyl group having 1 to 9 carbon atoms), an aralkyloxy group having 7 to 13 carbon atoms, an arylalkyl group having 7 to 13 carbon atoms, and an alkylaryl group having 7 to 13 carbon atoms. More specifically, １ ~R ４ may be a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and more specifically, １ ~R ４ may each independently be a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms.

[0157] In addition, in formula (1), R ５ ~R ８ are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, specifically a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, more specifically a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and when substituted, １ ~R ４ It should be noted that the R ５ ~R ８ is not an alkyl group but a hydrolyzable substituent, N-R ５ R ６ and N-R ７ R ８ The bond can be hydrolyzed to N--H in the presence of moisture, adversely affecting the processability of the polymer.

[0158] More specifically, in the compound represented by the formula (1), R １ ~R ４ is a methyl group or an ethyl group, and R ５ ~R ８ can be an alkyl group having 1 to 10 carbon atoms.

[0159] The amino group in the compound represented by the formula (1), i.e., N—R５ R ６ and N-R ７ R ８ is preferably a tertiary amino group. The tertiary amino group makes the compound represented by formula (1) have better processability when used as a modifying agent. ５ ~R ８ If a protecting group for protecting the amino group is bonded to the terminal of the polymer or if hydrogen is bonded to the terminal of the polymer, it may be difficult to realize the effect of the compound represented by formula (1). If hydrogen is bonded, the anion reacts with hydrogen during the modification process, losing its reactivity and making the modification reaction impossible. If a protecting group is bonded, the modification reaction occurs, but the terminal of the polymer is deprotected by hydrolysis during post-processing to become a primary or secondary amino group. The deprotected primary or secondary amino group may cause the viscosity of the compound to increase during subsequent blending, potentially resulting in reduced processability.

[0160] In addition, L in the compound represented by the formula (1) １ and L ２ are each independently a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms. １ and L ２ may each independently be an alkylene group having 1 to 10 carbon atoms, more specifically an alkylene group having 1 to 6 carbon atoms, such as a methylene group, an ethylene group, or a propylene group.

[0161] L in the compound represented by formula (1) １ and L ２ Regarding the above, the shorter the distance between the Si atom and the N atom in the molecule, the better the effect. However, when Si is directly bonded to N, there is a risk that the bond between Si and N may break during the subsequent treatment process, and the secondary amino group generated in this case is likely to be washed away by water during the post-treatment. In the modified styrene-butadiene rubber produced, it is difficult for the amino group, which promotes bonding with fillers such as silica, to bond with the filler, and as a result, the effect of improving the dispersibility of the filler may be reduced. In this way, when the improvement effect depending on the length of the bond between Si and N is taken into consideration, the above L １ and L ２is more preferably each independently an alkylene group having 1 to 3 carbon atoms such as a methylene group, an ethylene group, or a propylene group, and more specifically, can be a propylene group. １ and L ２ First, R １ ~R ４ It may be substituted with substituents as described above.

[0162] The compound represented by formula (1) is preferably, for example, any one of the compounds represented by the following structural formulas (1-1) to (1-5), because this allows for the realization of even better low loss properties.

[0163]

[0164] The compound represented by formula (1) has an alkoxysilane structure that bonds to the active terminal of the styrene-butadiene copolymer, while the Si—O—Si structure and three or more amino groups bonded to the terminal exhibit affinity for fillers such as silica, thereby promoting bonding between the filler and the modified styrene-butadiene rubber compared to conventional modifiers containing a single amino group per molecule. Furthermore, the degree of bonding at the active terminal of the styrene-butadiene copolymer is uniform, and when observing the change in molecular weight distribution before and after coupling, the molecular weight distribution remains constant without increasing after coupling compared to before coupling. Therefore, there is no deterioration in the physical properties of the modified styrene-butadiene rubber itself, and the aggregation of the filler in the rubber composition can be prevented, increasing the dispersibility of the filler, thereby improving the processability of the rubber composition. These effects, particularly when the rubber composition is applied to tires, enable a balanced improvement in wear resistance and wet grip performance.

[0165] The compound represented by formula (1) can be produced through a condensation reaction represented by the following reaction scheme.

[0166]

[0167] In the above reaction scheme, R １ ~R ８ , L １ and L ２and n are the same as those defined in the above formula (1), and R′ and R″ are any substituents that do not affect the condensation reaction. For example, R′ and R″ are each independently R １ ~R ４ It can be identical to any one of the following:

[0168] The reaction of the above reaction scheme proceeds in the presence of an acid, and any acid generally used in condensation reactions can be used without limitation. Those skilled in the art can select an optimal acid depending on various process variables such as the type of reactor in which the reaction is carried out, starting materials, and reaction temperature.

[0169] The styrene-butadiene rubber modified with a modifier containing the compound represented by formula (1) can have a narrow molecular weight distribution (Mw / Mn, also referred to as "polydispersity index (PDI)") of 1.1 to 3.0. If the molecular weight distribution of the modified styrene-butadiene rubber exceeds 3.0 or is less than 1.1, there is a risk of reduced tensile properties and viscoelasticity when applied to a rubber composition. Considering the significant effect of improving tensile properties and viscoelasticity by controlling the molecular weight distribution of the modified styrene-butadiene rubber, the molecular weight distribution of the modified styrene-butadiene rubber is preferably in the range of 1.3 to 2.0. By using the modifier, the modified styrene-butadiene rubber has a molecular weight distribution similar to that of the styrene-butadiene copolymer before modification.

[0170] The molecular weight distribution of the modified styrene-butadiene rubber can be calculated from the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn). The number average molecular weight (Mn) is the common average of the molecular weights of individual polymers calculated by measuring the molecular weights of n polymer molecules, summing the molecular weights, and dividing by n. The weight average molecular weight (Mw) represents the molecular weight distribution of the polymer composition. The average of the total molecular weight can be expressed in grams per mole (g / mol). The weight average molecular weight and number average molecular weight are each polystyrene-equivalent molecular weights analyzed by gel permeation chromatography (GPC).

[0171] Furthermore, the modified styrene-butadiene rubber satisfies the above-mentioned molecular weight distribution condition, and at the same time, the number average molecular weight (Mn) can be 50,000 g / mol to 2,000,000 g / mol, more specifically, 200,000 g / mol to 800,000 g / mol. The modified styrene-butadiene rubber can have a weight average molecular weight (Mw) of 100,000 g / mol to 4,000,000 g / mol, more specifically, 300,000 g / mol to 1,500,000 g / mol. If the weight average molecular weight (Mw) of the modified styrene-butadiene rubber is less than 100,000 g / mol or the number average molecular weight (Mn) is less than 50,000 g / mol, there is a risk of a decrease in tensile properties when applied to a rubber composition. Furthermore, if the weight average molecular weight (Mw) exceeds 4,000,000 g / mol or the number average molecular weight (Mn) exceeds 2,000,000 g / mol, the processability of the modified styrene-butadiene rubber decreases, resulting in a deterioration in the workability of the rubber composition, making kneading difficult, and making it difficult to sufficiently improve the physical properties of the rubber composition. More specifically, if the modified styrene-butadiene rubber simultaneously satisfies the conditions of the weight average molecular weight (Mw) and number average molecular weight (Mn) as well as the molecular weight distribution, when applied to a rubber composition, it can improve the viscoelasticity and processability of the rubber composition in a well-balanced manner.

[0172] The modified styrene-butadiene rubber preferably has a vinyl bond content in the butadiene moiety of 5% or more, more preferably 10% or more, and is preferably 60% or less. By adjusting the vinyl bond content in the butadiene moiety to fall within the above range, the glass transition temperature can be adjusted to an appropriate range.

[0173] The modified styrene-butadiene rubber may have a Mooney viscosity (MV) at 100°C of 40 to 140, specifically 60 to 100. A Mooney viscosity within this range can exhibit better processability. The Mooney viscosity can be measured using a Mooney viscometer, for example, a Monsanto MV2000E, at 100°C, a rotor speed of 2±0.02 rpm, and a large rotor. The sample used here is left at room temperature (23±3°C) for 30 minutes or more, and then 27±3 g of the sample is taken and filled into the die cavity. The platen is then operated to measure the viscosity.

[0174] As described above, the modified styrene-butadiene rubber is preferably modified at one end with a modifier containing a compound represented by the above general formula (1), and is preferably further modified at the other end with a modifier containing a compound represented by the following general formula (2). By modifying both ends of the modified styrene-butadiene rubber, the dispersibility of the filler in the rubber composition is further improved, and a tire using the rubber composition can achieve both a higher level of wear resistance and wet grip performance.

[0175]

[0176] In the above general formula (2), R ９ ~R １１ are each independently hydrogen, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 to 30 carbon atoms, a heteroalkyl group having 1 to 30 carbon atoms, a heteroalkenyl group having 2 to 30 carbon atoms, a heteroalkynyl group having 2 to 30 carbon atoms, a cycloalkyl group having 5 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or a heterocyclic group having 3 to 30 carbon atoms. １２ is a single bond; a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms; a substituted or unsubstituted cycloalkylene group having 5 to 20 carbon atoms; or a substituted or unsubstituted arylene group having 5 to 20 carbon atoms, wherein the substituent is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. １３is an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; a heterocyclic group having 3 to 30 carbon atoms; or a functional group represented by the following general formula (2a) or general formula (2b), wherein m is an integer of 1 to 5, and R １３ At least one of the functional groups is represented by the following general formula (2a) or (2b), and when m is an integer of 2 to 5, a plurality of R １３ may be the same as or different from each other.

[0177]

[0178] In the above general formula (2a), R １４ is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms; a substituted or unsubstituted cycloalkylene group having 5 to 20 carbon atoms; or a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, wherein the substituent is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. １５ and R １６ are each independently an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an alkylene group having 1 to 20 carbon atoms which is substituted or unsubstituted with an aryl group having 6 to 20 carbon atoms. １７ is hydrogen; an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; or a heterocyclic group having 3 to 30 carbon atoms; and X is an N, O, or S atom, provided that when X is O or S, R １７ does not exist.

[0179]

[0180] In the above general formula (2b), R １８is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms; a substituted or unsubstituted cycloalkylene group having 5 to 20 carbon atoms; or a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, wherein the substituent is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. １９ and R ２０ are each independently an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; or a heterocyclic group having 3 to 30 carbon atoms.

[0181] In addition, in the compound represented by the general formula (2), R ９ ~R １１ are each independently hydrogen; an alkyl group having 1 to 10 carbon atoms; an alkenyl group having 2 to 10 carbon atoms; or an alkynyl group having 2 to 10 carbon atoms; R １２ is a single bond; or an unsubstituted alkylene group having 1 to 10 carbon atoms, R １３ is an alkyl group having 1 to 10 carbon atoms; an alkenyl group having 2 to 10 carbon atoms; an alkynyl group having 2 to 10 carbon atoms; or a functional group represented by the above general formula (2a) or (2b), and in the above general formula (2a), R １４ is an unsubstituted alkylene group having 1 to 10 carbon atoms, and R １５ and R １６ are each independently an unsubstituted alkylene group having 1 to 10 carbon atoms, and R １７ is an alkyl group having 1 to 10 carbon atoms; a cycloalkyl group having 5 to 20 carbon atoms; an aryl group having 6 to 20 carbon atoms; or a heterocyclic group having 3 to 20 carbon atoms, and in the above general formula (2b), R １８ is an unsubstituted alkylene group having 1 to 10 carbon atoms, and R １９ and R ２０ may each independently be an alkyl group having 1 to 10 carbon atoms; a cycloalkyl group having 5 to 20 carbon atoms; an aryl group having 6 to 20 carbon atoms; or a heterocyclic group having 3 to 20 carbon atoms.

[0182] More specifically, the compound represented by the general formula (2) can be a compound represented by the following structural formulas (2-1) to (2-3).

[0183]

[0184] When the styrene-butadiene copolymer is modified with a modifying agent containing a compound represented by the general formula (2), the modifying agent containing the compound represented by formula (2) is used as a modification initiator. Specifically, for example, a butadiene monomer and a styrene monomer are polymerized in a hydrocarbon solvent in the presence of a modifying agent containing a compound represented by formula (2), thereby imparting a modifying group derived from the compound represented by formula (2) to the styrene-butadiene copolymer.

[0185] (Resin Component (B)) The rubber composition of this embodiment (rubber composition for outer layer rubber) contains a resin component (B).

[0186] The mass ratio (B / A1) of the resin component (B) to the isoprene-based rubber (A1) is preferably 0.5 or more. When the mass ratio (B / A1) of the resin component (B) to the isoprene-based rubber (A1) is 0.5 or more, the wear resistance of a tire to which the rubber composition is applied can be further improved, and the wet grip performance can be improved. From the same viewpoint, the mass ratio (B / A1) of the resin component (B) to the isoprene-based rubber (A1) is more preferably 0.65 or more, more preferably 0.7 or more, and more preferably 0.8 or more, and is more preferably 2.0 or less, more preferably 1.9 or less, and even more preferably 1.8 or less.

[0187] The content of the resin component (B) is not particularly limited, but is preferably 1 part by mass or more and less than 50 parts by mass per 100 parts by mass of the rubber component (A). When the content of the resin component (B) in the rubber composition is 1 part by mass or more per 100 parts by mass of the rubber component (A), the effect of improving abrasion resistance can be more reliably obtained, and when the content is less than 50 parts by mass, the resin component (B) is less likely to precipitate from the tire, and the effects of the resin component (B) can be fully exhibited. From the viewpoint of further enhancing the effects of the resin component (B), the content of the resin component (B) in the rubber composition is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, more preferably 9 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 17 parts by mass or more per 100 parts by mass of the rubber component (A). From the viewpoint of suppressing precipitation of the resin component (B) from the tire and suppressing deterioration in tire appearance, the content of the resin component (B) in the rubber composition is more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less, per 100 parts by mass of the rubber component (A).

[0188] The resin component (B) has an SP value difference of 1.40 (cal / cm) from that of the isoprene-based rubber (A1). ３ ) １／２ In this case, compatibility with the isoprene-based rubber (A1) is increased, the mobility of the rubber component is controlled, and the hysteresis loss (tan δ) in the low temperature range can be improved. As a result, the wet grip performance of a tire using the rubber composition is improved. From the viewpoint of further improving compatibility, the difference in SP value between the resin component (B) and the isoprene-based rubber (A1) is preferably 1.35 (cal / cm ３ ) １／２ It is preferable that the value is 0.50 (cal / cm ３ ) １／２ More preferably, it is 0.45 (cal / cm ３ ) １／２ More preferably, it is 0.30 (cal / cm ３ ) １／２ More preferably, it is 0.25 (cal / cm ３ ) １／２The difference in SP value between the resin component (B) and the isoprene-based rubber (A1) is more preferably 0.50 (cal / cm ３ ) １／２ When the content is not more than 100%, the compatibility between the resin component (B) and the isoprene-based rubber (A1) is further improved, and the wet grip performance of a tire using the rubber composition is improved.

[0189] The resin component (B) preferably has a softening point higher than 110°C and a weight-average molecular weight in polystyrene equivalent of 200 to 1600 g / mol. By applying a rubber composition containing such a resin component (B) to a tire, the wear resistance of the tire can be improved. In this specification, the softening point of the resin component is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2015 (ISO 28641:2010) is measured using a ring and ball softening point tester. The weight-average molecular weight of the resin component is measured by gel permeation chromatography (GPC), and the value calculated in polystyrene equivalent is calculated.

[0190] When the softening point of the resin component (B) is higher than 110°C, a tire to which the rubber composition is applied can be sufficiently reinforced and its wear resistance can be improved. From the viewpoint of the wear resistance of the tire, the softening point of the resin component (B) is preferably 116°C or higher, more preferably 120°C or higher, more preferably 123°C or higher, and even more preferably 127°C or higher. From the viewpoint of processability, the softening point of the resin component (B) is preferably 160°C or lower, more preferably 150°C or lower, more preferably 145°C or lower, more preferably 141°C or lower, and even more preferably 136°C or lower.

[0191] When the polystyrene-equivalent weight-average molecular weight of the resin component (B) is 200 g / mol or more, the resin component (B) is less likely to precipitate from the tire and the effects of the resin component (B) can be fully exhibited, and when it is 1600 g / mol or less, the resin component (B) is easily compatible with the rubber component (A). From the viewpoint of suppressing the precipitation of the resin component (B) from the tire and suppressing deterioration of the tire appearance, the polystyrene-equivalent weight-average molecular weight of the resin component (B) is preferably 500 g / mol or more, more preferably 550 g / mol or more, even more preferably 600 g / mol or more, even more preferably 650 g / mol or more, and still more preferably 700 g / mol or more. Furthermore, from the viewpoint of improving the compatibility of the resin component (B) with the rubber component (A) and further enhancing the effects of the resin component (B), the polystyrene-equivalent weight average molecular weight of the resin component (B) is more preferably 1570 g / mol or less, more preferably 1530 g / mol or less, more preferably 1500 g / mol or less, more preferably 1470 g / mol or less, more preferably 1430 g / mol or less, more preferably 1400 g / mol or less, more preferably 1370 g / mol or less, more preferably 1330 g / mol or less, more preferably 1300 g / mol or less, more preferably 1200 g / mol or less, more preferably 1100 g / mol or less, more preferably 1000 g / mol or less, and even more preferably 950 g / mol or less.

[0192] The weight average molecular weight (Mw ＨＲ ) (unit: g / mol) of the resin component (B) relative to the softening point (Ts ＨＲ ) (unit: °C) ratio (Ts ＨＲ / Mw ＨＲ) is preferably 0.07 or more, more preferably 0.083 or more, more preferably 0.095 or more, more preferably 0.104 or more, more preferably 0.125 or more, more preferably 0.135 or more, more preferably 0.14 or more, and even more preferably 0.141 or more. ＨＲ / Mw ＨＲ ) is preferably 0.25 or less, more preferably 0.24 or less, more preferably 0.23 or less, more preferably 0.19 or less, more preferably 0.18 or less, and even more preferably 0.17 or less.

[0193] The resin component (B) is preferably at least partially hydrogenated. In this case, compatibility with the isoprene-based rubber (A1) is improved, the mobility of the rubber component is controlled, and the hysteresis loss (tan δ) in the low temperature range can be improved. As a result, the wet grip performance of a tire using the rubber composition is improved.

[0194] The above-mentioned at least partially hydrogenated resin component means a resin obtained by reducing and hydrogenating a resin. Resins that can be used as raw materials for the hydrogenated resin component (B) include terpene-based resins, rosin-based resins, C ５ based resin, C ５ -C ９ based resin, C ９ Examples of suitable resins include terpene-based resins, cyclopentadiene-based resins, aromatic-based resins, coumarone resins, indene resins, coumarone-indene-based resins, olefin-based resins, polyurethane resins, and acrylic resins. These resins may be used singly or in combination of two or more. Note that terpene-based resins and rosin-based resins are naturally derived, sustainable resins, and therefore can further reduce the environmental impact and can further improve tire performance, such as tire grip performance on various road surface conditions, including dry roads, wet roads, snow-covered roads, and icy roads. ５ based resin, C ９ based resin, C ５ -C ９The cyclopentadiene-based resin and the cyclopentadiene-based resin can further improve abrasion resistance, while the aromatic resin can improve grip performance, abrasion resistance, and rubber strength in a well-balanced manner.

[0195] The terpene resin is a solid resin obtained by blending turpentine, which is obtained simultaneously with the extraction of rosin from pine trees, or a polymerization component separated therefrom, and polymerizing the blend using a Friedel-Crafts catalyst. Examples of such resins include β-pinene resin and α-pinene resin. Terpene resins also include terpene-aromatic compound resins, representative examples of which include terpene-phenol resin and styrene-terpene resin. Terpene-phenol resins can be obtained by reacting terpenes with various phenols using a Friedel-Crafts catalyst, or by further condensing the terpene with formalin. The styrene-terpene resin can be obtained by reacting styrene with terpenes using a Friedel-Crafts catalyst. The terpenes used as raw materials are not particularly limited; monoterpene hydrocarbons such as α-pinene and limonene are preferred, with those containing α-pinene being more preferred, and α-pinene being particularly preferred.

[0196] Examples of the rosin-based resin include natural resin rosins such as gum rosin, tall oil rosin, and wood rosin contained in raw pine resin and tall oil, and examples of modified rosins, rosin derivatives, and modified rosin derivatives include polymerized rosin and partially hydrogenated rosin thereof; glycerin ester rosin and partially hydrogenated rosin thereof and fully hydrogenated rosin thereof; pentaerythritol ester rosin and partially hydrogenated rosin thereof and polymerized rosin; and the like.

[0197] Said C ５ As a resin based on C, there is C obtained by thermal decomposition of naphtha in the petrochemical industry. ５ and aliphatic petroleum resins obtained by (co)polymerizing the distillate. ５The fraction usually contains olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene, and diolefinic hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 3-methyl-1,2-butadiene.

[0198] Said C ５ -C ９ The C-based resin is ５ -C ９ It refers to synthetic petroleum resin, ５ -C ９ Examples of the resin include petroleum-derived C ５ -C １１ The fraction was treated with AlCl ３ , B.F. ３ More specifically, copolymers containing styrene, vinyl toluene, α-methyl styrene, indene, etc. as the main component may be mentioned. ５ -C ９ As the resin, ９ Resins containing less of the above components are preferred from the viewpoint of compatibility with the rubber component (A). ９ "Low amount of the above components" means that the C ９ This means that the content of the above components is less than 50% by mass, preferably 40% by mass or less.

[0199] Said C ９ The C-based resin is ９ This refers to synthetic petroleum resins, such as AlCl ３ or BF ３ Using a Friedel-Crafts type catalyst such as C ９ It refers to a solid polymer obtained by polymerizing the fraction. ９ Examples of the resin include copolymers containing indene, α-methylstyrene, vinyltoluene, etc. as main components.

[0200] The cyclopentadiene-based resin refers to a resin containing a unit derived from a cyclopentadiene-based monomer as a monomer unit. Examples of the cyclopentadiene-based resin include a homopolymer of a cyclopentadiene-based monomer, a copolymer of two or more cyclopentadiene-based monomers, and a copolymer of a cyclopentadiene-based monomer and another monomer. Here, examples of the cyclopentadiene-based monomer include cyclopentadiene, dicyclopentadiene, and tricyclopentadiene. Among these, dicyclopentadiene is preferred. That is, the cyclopentadiene-based resin is preferably a dicyclopentadiene-based resin. The dicyclopentadiene-based resin is, for example, a copolymer of AlCl ３ or BF ３ The term "dicyclopentadiene-based resin" refers to a resin obtained by polymerizing dicyclopentadiene using a Friedel-Crafts catalyst such as Benzene, etc. Dicyclopentadiene-based resins include homopolymers of dicyclopentadiene, copolymers of dicyclopentadiene and aromatic monomers, copolymers of dicyclopentadiene and C ９ Examples include copolymers with distillates (vinyl toluene, indene, etc.).

[0201] The aromatic resin refers to a resin containing units derived from aromatic monomers as monomer units. Examples of the aromatic resin include homopolymers of aromatic monomers, copolymers of two or more aromatic monomers, and copolymers of aromatic monomers with other monomers. Examples of the aromatic monomer include styrene-based monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, and p-phenylstyrene; phenol-based monomers such as phenol, alkylphenol, and alkoxyphenol; and naphthol-based monomers such as naphthol, alkylnaphthol, and alkoxynaphthol.

[0202] The resin used as the raw material for the hydrogenated resin component (B) is, for example, C ５ A resin (C) copolymerized with the fraction and dicyclopentadiene (DCPD) ５-DCPD-based resin). When the dicyclopentadiene-derived component is 50% by mass or more in the total amount of the resin, C ５ -DCPD-based resins are included in dicyclopentadiene-based resins. When the dicyclopentadiene-derived component is less than 50% by mass in the total amount of resin, C ５ -DCPD resin is C ５ The same applies to cases where a small amount of a third component is contained.

[0203] From the viewpoints of increasing the compatibility between the rubber component (A) and the resin component (B), further improving the abrasion resistance of a tire to which the rubber composition is applied, and further improving the wet grip performance, the resin component (B) is preferably a hydrogenated terpene resin, a hydrogenated C ５ based resin, hydrogenated C ５ -C ９ and hydrogenated dicyclopentadiene resins (hydrogenated DCPD resins), and ５ Resin and hydrogenated C ５ -C ９ It is more preferable that the resin is at least one selected from the group consisting of hydrogenated C ５ Furthermore, the resin component (B) is preferably a resin having at least a hydrogenated DCPD structure or a hydrogenated cyclic structure in the monomer.

[0204] Furthermore, the resin component (B) may be modified to introduce a functional group that interacts with the filler (C), such as carbon black or silica. Examples of such functional groups include amino groups, amide groups, isocyanate groups, imino groups, imidazole groups, urea groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxyl groups, nitrile groups, pyridyl groups, alkoxy groups, hydroxyl groups, oxy groups, epoxy groups, ether groups, carbonyl groups, oxycarbonyl groups, silyl groups, alkoxysilyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, and thiocarbonyl groups.

[0205] Commercially available products can be used as the resin component (B), and examples of commercially available products of the resin component (B) include products from Eastman Chemical, ENEOS Corporation, Arakawa Chemical Industries, Ltd., ExxonMobil Corporation, Kraton, Yasuhara Chemical Co., Ltd., Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Kraton Polymers, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., Taoka Chemical Co., Ltd., and the like.

[0206] (Filler (C)) The rubber composition (rubber composition for outer layer rubber) of this embodiment contains filler (C). By containing filler (C), the reinforcing properties of the rubber composition are improved. Examples of fillers include carbon black, silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica.

[0207] The content of the filler (C) in the rubber composition is preferably in the range of 40 to 125 parts by mass per 100 parts by mass of the rubber component (A). When the content of the filler (C) in the rubber composition is 40 parts by mass or more per 100 parts by mass of the rubber component (A), the tire using the rubber composition is sufficiently reinforced and the wear resistance can be improved. When the content of the filler (C) in the rubber composition is 125 parts by mass or less, the modulus of elasticity of the rubber composition does not become too high, and the wet grip performance of the tire using the rubber composition is improved. From the viewpoint of further improving the wear resistance of the tire, the content of the filler (C) in the rubber composition is more preferably 45 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 55 parts by mass or more per 100 parts by mass of the rubber component (A). Furthermore, from the viewpoint of improving the wet grip performance of the tire, the content of the filler (C) in the rubber composition is more preferably 105 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 95 parts by mass or less per 100 parts by mass of the rubber component (A).

[0208] Carbon Black Carbon black reinforces the rubber composition and can improve the abrasion resistance of the rubber composition. Examples of carbon black include plant-derived carbon black and recycled carbon black (also called "recycled carbon black" or "recycled carbon black").

[0209] The content of carbon black (total of recycled carbon black and carbon black other than recycled carbon black) in the rubber composition is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of rubber component (A) from the viewpoint of improving the wear resistance of the rubber composition and a tire using the same. Furthermore, from the viewpoint of workability of the rubber composition, the content of carbon black in the rubber composition is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, per 100 parts by mass of rubber component (A).

[0210] --Recycled Carbon Black-- In the rubber composition of this embodiment, the filler (C) preferably contains recycled carbon black. This is because when virgin carbon black (such as plant-derived carbon black) is replaced with recycled carbon black, abrasion resistance tends to improve.

[0211] As used herein, "recycled carbon black" refers to carbon black recovered from recycled waste materials. Examples of such waste include waste rubber, used tires, and waste oil. Waste rubber refers to all discarded rubber, including not only waste generated from rubber products but also unwanted scraps generated during the production or repair of rubber products. Examples of scraps include buffing powder and peeled rubber. Buffing powder is fine rubber generated during the buffing process of scraping the tread portion remaining on the base tire during tire retreading, for example. Peeled rubber is a long piece of rubber, e.g., 1 to 2 cm wide, peeled from the surface of a rubber product such as a tire. Peeled rubber is generated by scraping the surface of a rubber product such as a tire using a U- or V-shaped knife like a peeler. Furthermore, waste rubber is not limited to crosslinked rubber but also includes unvulcanized rubber. Rubber products include, for example, final products such as tires and rubber hoses, as well as rubber parts or components during the manufacturing process of final products. Used tires may be tires to be retreaded, or may be tires discarded for some reason, such as tires generated during tire replacement or scrapping, or ELTs (End-of-Life Tires) that have reached the end of their service life. Waste oils are not limited to those generated during the decomposition of plastics and rubber, but also include used oils discharged from industry, such as animal and vegetable oils, lubricating oils, insulating oils, and cutting oils. Among these, waste oils that contain no non-organic components, such as those derived from silicone rubber or polyvinyl chloride, are desirable. Furthermore, waste oils containing carbon black or rubber containing carbon black are desirable. "Recycled carbon black" differs from carbon black produced directly from hydrocarbons such as petroleum, natural gas, and coal, i.e., non-recycled carbon black. Note that "used" here refers not only to waste oils discarded after actual use, but also to waste oils that were produced but discarded without actually being used.

[0212] The recycled carbon black is preferably obtained by pyrolysis of a vulcanized rubber product containing carbon black. Recycled carbon black obtained by pyrolysis of a vulcanized rubber product containing carbon black is readily available because vulcanized rubber products containing carbon black are readily available and can be easily obtained by pyrolysis. Furthermore, the recycled carbon black is preferably obtained from the solid residue produced by the pyrolysis of the vulcanized rubber product containing carbon black. When a rubber product containing carbon black is pyrolyzed, a solid residue and a volatile component (oil) are obtained, and recycled carbon black can be recovered from either of them. When recovering carbon black from the volatile component, the oil component with a specific gravity suitable for producing carbon black can be recovered and used to produce carbon black using existing carbon black production methods (e.g., JP 2015-520259 A). Unlike carbon black recovered from solid residues, this method offers advantages such as no impurities and no mixing of different grades. In addition, in the production of environmentally friendly carbon black, various options are available, including oils obtained by recovering volatile components from rubber pyrolysis, as described above, as well as vegetable oils and oils derived from waste plastics. However, edible resources such as vegetable oils are needed for other uses, such as food, and there are challenges in securing sufficient quantities, as well as the environmental impact of expanding cultivated land. Furthermore, oils derived from waste plastics are also used for other purposes, such as horizontal plastic recycling, so supply issues are also a concern. On the other hand, using volatile components (oils) produced by the pyrolysis of vulcanized rubber products, particularly tires, allows for the continued use of existing materials due to the tire industry's ongoing system of using existing materials, thereby reducing the consumption of new materials in new tire production and contributing to a reduction in the industry's environmental impact. The grade of carbon black is not particularly limited, and examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762.

[0213] Solid residues obtained by pyrolysis of waste materials such as used rubber and used tires contain ash in addition to carbon black. The ash is derived from non-volatile components contained in the rubber and tires. Therefore, recycled carbon black obtained from the solid residues has a relatively low carbon black content. On the other hand, considering the various physical properties required for tires manufactured using recycled carbon black, the higher the carbon content of the recycled carbon black, the better. The carbon content of the recycled carbon black is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 87% by mass or more, and particularly preferably 89% by mass or more. Furthermore, the carbon content of the recycled carbon black is preferably 97% by mass or less. Note that the carbon content does not include adsorbed moisture.

[0214] Specific examples of the ash include zinc oxide, zinc sulfide, silica, iron compounds (iron oxide), calcium oxide, aluminum oxide, and magnesium oxide. In the case of recycled carbon black produced from solid residue obtained by pyrolysis of waste, a certain amount of ash remains even after various processes for removing the ash. In this embodiment, the recycled carbon black is allowed to contain ash. In one embodiment, the lower limit of the ash content of the recycled carbon black may be 0.5% by mass.

[0215] The recycled carbon black can also be obtained from a pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3,427,975, citing "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, describes that recycled carbon black can be obtained by pyrolysis of organic materials at 550-800°C in the absence of oxygen, or by vacuum pyrolysis at relatively low temperatures (paragraph

[0027] ). Carbon black obtained from such pyrolysis processes typically lacks functional groups on its surface, as mentioned in paragraph

[0004] of Japanese Patent Publication No. 6,856,781 (Comparison of the Surface Morphology and Chemistry of Pyrolytic Carbon Black and Commercially Available Carbon Black, Powder Technology 160 (2005) pp. 190-193).

[0216] The recycled carbon black may lack functional groups on its surface, or may be treated to include functional groups on its surface. The treatment to include functional groups on the surface of recycled carbon black can be carried out by conventional methods. For example, in European Patent Application Publication No. 3,173,251, carbon black obtained by a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Furthermore, in Japanese Patent Publication No. 6,856,781, carbon black obtained by a pyrolysis process is treated with an amino acid compound containing at least one thiol or disulfide group to obtain surface-activated carbon black. The recycled carbon black according to this embodiment also includes carbon blacks treated to include functional groups on their surfaces.

[0217] Furthermore, examples of thermal decomposition of crosslinked rubber products (vulcanized rubber products) such as used tires include thermal decomposition methods at temperatures of 650° C. or higher.

[0218] The crosslinked rubber products used for the decomposition may be grouped by the type of rubber component previously compounded, and then the decomposition step may be performed for each group. Alternatively, the crosslinked rubber products may be grouped by the type of filler previously compounded (e.g., type of carbon black, type of silica, mixing ratio of carbon black and silica, etc.), and then the decomposition step may be performed for each group. Furthermore, the crosslinked rubber products may be grouped by both type of rubber component and type of filler, and then the decomposition step may be performed for each group. When the decomposition step is performed for each group in this way, recycled carbon black with more uniform physical properties can be obtained, and when the recycled carbon black is compounded again into a rubber component, a rubber composition with better performance can be obtained.

[0219] Furthermore, when the crosslinked rubber product used in the degradation is derived from tires, the tires may be grouped in advance by type (e.g., for passenger cars, for trucks and buses, for large vehicles such as off-road vehicles, for aircraft, for agricultural vehicles, etc.), and the degradation step may be carried out for each group. Alternatively, the tires may be grouped in advance by tire component (e.g., tread rubber, sidewall rubber, bead rubber, steel cord-coated rubber, organic fiber-coated rubber, pad rubber, cushion rubber, etc.), and the degradation step may be carried out for each group. Furthermore, the tires may be grouped both by type and by tire component, and the degradation step may be carried out for each group. When the degradation step is carried out for each group in this way, recycled carbon black with more uniform physical properties can be obtained, and therefore, when the recycled carbon black is blended again into a rubber component, a rubber composition with better performance can be obtained.

[0220] The recycled carbon black has a nitrogen adsorption specific surface area of ​​40 to 100 m as measured by the BET method. ２ / g, and 50 to 90m ２ / g, and more preferably 55 to 75m ２ In this specification, the nitrogen adsorption specific surface area of ​​recycled carbon black measured by the BET method is a statistical thickness specific surface area (STSA) determined in accordance with ASTM D6556.

[0221] The pH of the recycled carbon black is preferably 4 to 12, more preferably 5 to 11, and particularly preferably 6 to 10. In this specification, the pH of the recycled carbon black is determined in accordance with ASTM D1512.

[0222] The recycled carbon black preferably has a toluene color transmittance of 60% or more, more preferably 70% or more, and particularly preferably 80% or more. Herein, the toluene color transmittance of recycled carbon black is determined in accordance with ASTM D1618.

[0223] The recycled carbon black preferably has a heat loss of 3% by mass or less, more preferably 2.5% by mass or less, and particularly preferably 2% by mass or less at 125°C. Herein, the heat loss of recycled carbon black at 125°C is determined in accordance with ASTM D1509.

[0224] The recycled carbon black preferably has a sulfur content of 5% by mass or less, more preferably 3.5% by mass or less, and particularly preferably 3% by mass or less.

[0225] The recycled carbon black preferably has a 35 mesh sieve residue of 20 mass ppm or less, more preferably 15 mass ppm or less, and particularly preferably 10 mass ppm or less. Herein, the 35 mesh sieve residue of recycled carbon black is determined in accordance with ASTM D1514.

[0226] The recycled carbon black preferably has a 325 mesh (44 μm) sieve residue of 1000 mass ppm or less, more preferably 700 mass ppm or less, and particularly preferably 300 mass ppm or less. Herein, the 325 mesh (44 μm) sieve residue of the recycled carbon black is determined in accordance with ASTM D1514.

[0227] The recycled carbon black preferably has a pellet hardness of 100 cN or less, more preferably 90 cN or less, and particularly preferably 80 cN or less. Herein, the pellet hardness of recycled carbon black is determined in accordance with ASTM D5230.

[0228] The recycled carbon black preferably has a pellet fine powder content of 10% by mass or less, more preferably 7% by mass or less, and particularly preferably 5% by mass or less. Herein, the pellet fine powder content of recycled carbon black is determined in accordance with ASTM D1508.

[0229] The particle size (D97) of the recycled carbon black is preferably 25 μm or less, more preferably 15 μm or less, and particularly preferably 10 μm or less. Here, in this specification, the particle size (D97) of the recycled carbon black is determined using a laser diffraction particle size distribution analyzer, assuming a refractive index of 1.33 for water and a refractive index of 1.75 for the filler.

[0230] The recycled carbon black preferably contains particles of 5 μm or less in a proportion of 50% by volume or more, more preferably 70% by volume or more, and particularly preferably 80% by volume or more.

[0231] The recycled carbon black preferably has an ash content of 25% by mass or less, more preferably 20% by mass or less, and particularly preferably 15% by mass or less. When the ash content of the recycled carbon black is 25% by mass or less, the physical properties of a tire to which the rubber composition is applied can be improved. Herein, the ash content of the recycled carbon black is determined in accordance with ASTM D8474 and D1506.

[0232] The recycled carbon black preferably has an oil absorption number (OAN) of 70 to 120 mL / 100 g, more preferably 75 to 110 mL / 100 g, and particularly preferably 80 to 100 mL / 100 g. Herein, the OAN of recycled carbon black is determined in accordance with ASTM D2414.

[0233] The recycled carbon black preferably has an oil absorption (COAN) of a compressed sample of 50 to 110 mL / 100 g, more preferably 60 to 100 mL / 100 g, and particularly preferably 70 to 90 mL / 100 g. Herein, the COAN of the recycled carbon black is determined in accordance with ASTM D3493.

[0234] Commercially available recycled carbon black can be used. For example, Enrestec's product name "PB365" can be mentioned as such a commercially available product. PB365 is a recycled carbon black produced through the thermal decomposition of used tires, and has a nitrogen adsorption specific surface area of ​​73.6 m2 as measured by the BET method. ２ / g and contains about 17% by mass of ash.

[0235] The amount of recycled carbon black is preferably 1 to 100 parts by mass, more preferably 5 to 80 parts by mass, even more preferably 5 to 50 parts by mass, still more preferably 5 to 30 parts by mass, and particularly preferably 5 to 20 parts by mass, per 100 parts by mass of the rubber component. When the amount of recycled carbon black is 5 parts by mass or more per 100 parts by mass of the rubber component, the effect of improving the proportion of sustainable materials in a tire to which the rubber composition is applied is significant, and when the amount is 50 parts by mass or less, the fracture resistance of the rubber composition can be more reliably maintained.

[0236] --Carbon Black Other Than Recycled Carbon Black-- The rubber composition of this embodiment may further contain, as filler (C), a carbon black other than recycled carbon black (virgin carbon black) in addition to the recycled carbon black described above. Examples of carbon black other than recycled carbon black include plant-derived carbon black, such as those derived from castor oil and pine oil. The grade of the carbon black is not particularly limited, and examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available carbon blacks can be used, including those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., and Birla Carbon. These carbon blacks may be used alone or in combination.

[0237] The nitrogen adsorption specific surface area (N ２ The nitrogen adsorption specific surface area (N SA) of carbon black is not particularly limited and can be adjusted as appropriate. ２ SA) is 20m ２ / g or more is preferable, and 50m ２ / g or more is more preferable, and 70m ２ / g or more is more preferable, ２ / g or more is more preferable, and ２ / g or less is preferable, and 150m ２ / g or less is more preferable, and 130m ２ / g or less is more preferable. In this specification, the nitrogen adsorption specific surface area (N ２ SA) is determined according to JIS K 6217-2:2017 (ISO 4652:2012).

[0238] -Silica- The rubber composition of this embodiment preferably contains silica. Examples of the silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate. Among these, wet silica is preferred because it contains a large number of silanol groups. These silicas may be used alone or in combination of two or more. Commercially available silicas can be used, and examples of commercially available silicas include products from Tosoh Silica Corporation, Evonik, Solvay, Solvay Japan, and Tokuyama Corporation.

[0239] From the viewpoint of reducing environmental impact, silica derived from siliceous plants is preferred as the silica. Examples of siliceous plants include mosses, ferns, horsetails, Cucurbitaceae, Urticaceae, and Gramineae plants. Among these plants, grasses are preferred. Examples of grasses include rice, bamboo, and sugarcane, with rice being preferred. Rice is widely cultivated for food and therefore can be procured locally over a wide area. Furthermore, rice husks are generated in large quantities as industrial waste, making it easy to secure a sufficient supply. Therefore, from the viewpoint of availability, silica derived from rice husks (hereinafter also referred to as "rice husk silica") is particularly preferred as silica. The use of rice husk silica allows for the effective use of rice husks, which are industrial waste, and also allows for the local procurement of raw materials near tire manufacturing plants, thereby reducing the energy and costs involved in transportation and storage, which is environmentally preferable from various viewpoints. The rice husk silica may be rice husk charcoal powder obtained by carbonizing rice husks by heating, or may be precipitated silica produced by a wet process using an alkali silicate aqueous solution, which is prepared by extracting rice husk ash generated when rice husks are burned as fuel in a biomass boiler with an alkali. The method for producing the rice husk charcoal is not particularly limited, and various known methods can be used. For example, rice husk charcoal can be obtained by pyrolyzing the rice husks by steaming them in a kiln. The rice husk charcoal obtained in this manner is pulverized using a known pulverizer (e.g., a ball mill), and then sorted and classified into a predetermined particle size range to obtain rice husk charcoal powder. The rice husk-derived precipitated silica can be produced by the method described in JP 2019-38728 A. From the perspective of reducing environmental impact, it is also preferable to use silica obtained by extracting silicic acid components from silicon wafer scraps, glass bottles, etc., which are used as raw materials for semiconductors, and recycling the extracted silica.

[0240] The nitrogen adsorption specific surface area (N ２ SA) is 80m ２ / g or more 330m ２ The nitrogen adsorption specific surface area (N ２ SA) is 80m ２ / g or more, a tire to which the rubber composition is applied can be sufficiently reinforced, and the wear resistance of the tire can be further improved. ２ SA) is 330m ２ When the modulus of elasticity of the rubber composition is less than 1 / g, the rubber composition does not become too high, and the wet grip performance of a tire using the rubber composition is improved. ２ SA) is 110m ２ / g or more, and ２ / g or more, and ２ / g or more, and ２ / g or more. From the viewpoint of further improving the wet grip performance of the tire, the nitrogen adsorption specific surface area (N ２ SA) is 300m ２ / g or less, and ２ / g or less is more preferable, and 270m ２ / g or less. In this specification, the nitrogen adsorption specific surface area (N ２ SA) is a value measured by the BET method in accordance with ASTM D3037-93.

[0241] From the viewpoint of improving the mechanical strength and abrasion resistance of the tire, the content of silica in the rubber composition is preferably 40 parts by mass or more, more preferably 45 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 55 parts by mass or more, per 100 parts by mass of the rubber component (A). Also, from the viewpoint of improving the wet grip performance of the tire, the content of silica in the rubber composition is preferably 125 parts by mass or less, more preferably 105 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 95 parts by mass or less, per 100 parts by mass of the rubber component (A).

[0242] When filler (C) contains silica in addition to carbon black, the proportion of silica in the total content of silica and carbon black is not particularly limited and can be adjusted appropriately.For example, the proportion of silica in the total content of silica and carbon black is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more.In addition, the proportion of silica in the total content of silica and carbon black is preferably 98% by mass or less.

[0243] Furthermore, when the filler (C) contains silica in addition to carbon black, the proportion of silica in the filler (C) is preferably 70% by mass or more. By having the proportion of silica in the filler (C) be 70% by mass or more, the mechanical strength of a tire to which the rubber composition is applied can be improved, and the wear resistance can be further improved. The proportion of silica in the filler (C) is more preferably 80% by mass or more, even more preferably 85% by mass or more, and even more preferably 90% by mass or more but less than 100% by mass.

[0244] (Antioxidant (D)) The rubber composition of the present embodiment (rubber composition for outer layer rubber) contains an antioxidant (D). The antioxidant (D) has the effect of preventing aging of the rubber composition and a tire using the same.

[0245] The mass ratio (B / D) of the resin component (B) to the antioxidant (D) is preferably 2 or more and 40 or less. Within this range, a better balance can be maintained between the effect of improving the abrasion resistance and the effect of improving the ozone resistance of the rubber composition. From the same viewpoint, the mass ratio (B / D) of the resin component (B) to the antioxidant (D) is more preferably 3 or more and more preferably 30 or less.

[0246] —Phenylenediamine-Based Antiaging Agent (D1) of Formula (d1)— The phenylenediamine-based antiaging agent (D1) is a compound represented by the following general formula (d1): [In the formula, R １０１ and R １０２ are each independently an alkyl group or an aryl group having 7 or more carbon atoms, and R １０１ and R１０２ at least one of which is an alkyl group having 7 or more carbon atoms.] The phenylenediamine-based antioxidant (D1) represented by general formula (d1) has the effect of improving the ozone resistance of a rubber composition and can suppress the occurrence of cracks in tires to which the rubber composition is applied. Furthermore, the phenylenediamine-based antioxidant (D1) represented by the above general formula (d1) has a small environmental impact.

[0247] In the above general formula (d1), R １０１ and R １０２ are each independently an alkyl group or an aryl group having 7 or more carbon atoms, and R １０１ and R １０２ At least one of the groups is an alkyl group having 7 or more carbon atoms. Examples of the alkyl group having 7 or more carbon atoms include a 1,2-dimethylpentyl group, a 1,3-dimethylpentyl group, a 1,4-dimethylpentyl group, a 2,3-dimethylpentyl group, a 2,4-dimethylpentyl group, a 3,4-dimethylpentyl group, a 1-methylhexyl group, a 2-methylhexyl group, an n-heptyl group, a 1,2-dimethylhexyl group, a 1,3-dimethylhexyl group, a 1,4-dimethylhexyl group, a 1,5-dimethylhexyl group, a 2,3-dimethylhexyl group, a 2,4-dimethylhexyl group, a 2,5-dimethylhexyl group, a 3,4-dimethylhexyl group, a 3,5-dimethylhexyl group, a 1-methylheptyl group, a 2-methylheptyl group, an n-octyl group, various decyl groups, and various dodecyl groups. Of these, a 1,4-dimethylpentyl group and a 1-methylheptyl group are preferred. Examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, a cumenyl group, a mesyl group, an α-naphthyl group, a β-naphthyl group, an ethylphenyl group, an n-propylphenyl group, an isopropylphenyl group, an n-butylphenyl group, a t-butylphenyl group, various dimethylphenyl groups, various diethylphenyl groups, various methylethylphenyl groups, various trimethylphenyl groups, various dimethylethylphenyl groups, various methyldiethylphenyl groups, and various triethylphenyl groups, and among these, a phenyl group is preferred.

[0248] R in the above general formula (d1) １０１ and R １０２At least one of R is an alkyl group having 7 or more carbon atoms. １０１ and R １０２ The other of R is preferably a phenyl group. １０１ and R １０２ one of R is an alkyl group having 7 or more carbon atoms, １０１ and R １０２ The phenylenediamine-based antioxidant (D1), in which the other radical is a phenyl group, can further improve the ozone resistance of the rubber composition and can further suppress the occurrence of cracks in tires to which the rubber composition is applied.

[0249] R in the above general formula (d1) １０１ and R １０２ At least one of R preferably has 7 or 8 carbon atoms. １０１ and R １０２ The phenylenediamine-based antioxidant (D1), at least one of which has 7 or 8 carbon atoms, can further improve the ozone resistance of the rubber composition and can further suppress the occurrence of cracks in tires to which the rubber composition is applied.

[0250] Specific examples of the phenylenediamine-based antioxidant (D1) represented by the general formula (d1) include N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N-phenyl-N'-(1-methylheptyl)-p-phenylenediamine (8PPD), N-phenyl-N'-(1,4-dimethylpentyl)-p-phenylenediamine (7PPD), etc. These phenylenediamine-based antioxidants (D1) may be used alone or in combination of two or more.

[0251] The mass ratio (D1 / A1) of the phenylenediamine-based antioxidant (D1) to the isoprene-based rubber (A1) is preferably greater than 0.025. When the mass ratio (D1 / A1) is greater than 0.025, the effect of improving ozone resistance can be more sufficiently obtained. In addition, from the viewpoint of further improving ozone resistance, the mass ratio (D1 / A1) is preferably 0.03 or more. On the other hand, the upper limit of the mass ratio (D1 / A1) is not particularly limited, but from the viewpoint of better maintaining physical properties other than ozone resistance, it is preferably 0.1 or less.

[0252] The proportion of the phenylenediamine-based antioxidant (D1) in the antioxidant (D) is not particularly limited, but is preferably, for example, 50% by mass or more, which can further improve ozone resistance.

[0253] -Aminoquinoline Antiaging Agent (D5) of Formula (d5)- The aminoquinoline antiaging agent (D5) is an aminoquinoline antiaging agent represented by the following general formula (d5): [In the formula, is a single bond or a double bond, R ５０１ and R ５０２ are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a phenyl group; R ５０３ , R ５０４ , R ５０５ , R ５０６ , R ５０７ , R ５０８ , R ５０９ and R ５１０ are each independently hydrogen or an alkyl group having 1 to 12 carbon atoms.] The aminoquinoline antioxidant (D5) represented by general formula (d5) has the effect of improving the ozone resistance of a rubber composition and can suppress the occurrence of cracks in tires to which the rubber composition is applied. Furthermore, the aminoquinoline antioxidant (D5) represented by general formula (d5) has a small environmental impact.

[0254] In the above general formula (d5), is a single bond or a double bond, preferably a double bond; R ５０１ and R ５０２are each independently hydrogen, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a phenyl group, and are preferably hydrogen or a phenyl group; ５０３ , R ５０４ , R ５０５ , R ５０６ , R ５０７ , R ５０８ , R ５０９ and R ５１０ are each independently hydrogen or an alkyl group having 1 to 12 carbon atoms, and are preferably hydrogen or a methyl group.

[0255] R in the above general formula (d5) ５０１ , R ５０２ , R ５０３ , R ５０４ , R ５０５ , R ５０６ , R ５０７ , R ５０８ , R ５０９ and R ５１０ With regard to the above, the alkyl group having 1 to 12 carbon atoms may be linear or branched. Examples of the alkyl group having 1 to 12 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, and various decyl groups. The number of carbon atoms in the alkyl group is preferably in the range of 1 to 8, more preferably in the range of 1 to 6, even more preferably in the range of 1 to 4, and particularly preferably in the range of 1 to 3. R in the above general formula (d5) ５０１ and R ５０２ Regarding the above, examples of the cycloalkyl group having 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a 1-methylcyclopentyl group, a 2-methylcyclopentyl group, and a 3-methylcyclopentyl group.

[0256] Specific examples of the aminoquinoline antioxidants represented by the general formula (d5) include those represented by the following structural formulas (d5-1) to (d5-94): These aminoquinoline antioxidants (D5) may be used singly or in combination of two or more.

[0257] Among these, as the aminoquinoline antioxidant represented by the above general formula (d5), a compound represented by structural formula (d5-1) is particularly preferred from the viewpoint of crack suppression. A rubber composition containing a compound represented by structural formula (d5-1) as an antioxidant, and thus a tire using such a rubber composition, has excellent ozone resistance and can further suppress the occurrence of cracks. Therefore, a tire containing a compound represented by structural formula (d5-1) as an antioxidant has excellent ozone resistance.

[0258] There are no particular limitations on the method for producing the aminoquinoline antioxidant represented by the above general formula (d5). For example, when an aromatic amine compound is used as a starting material, the method comprises the steps of: (i) reacting the aromatic amine compound with sodium nitrite in the presence of an acid to produce an aromatic amine compound having a nitroso group; (ii) reducing the produced nitroso group with sodium borohydride or the like to produce an aromatic diamine compound; and (iii) reacting the produced aromatic diamine compound with a ketone compound such as acetone to form a condensed ring, thereby producing a compound having a 6-amino-1,2-dihydroquinoline skeleton, i.e., the compound represented by the above general formula (d5), In addition, if desired, (iv) the compound having a 6-amino-1,2-dihydroquinoline skeleton thus produced can be reduced with hydrogen in the presence of a palladium-supported carbon catalyst to produce a compound having a 6-amino-1,2,3,4-tetrahydroquinoline skeleton, i.e., a compound represented by the above general formula (d5), Compounds can be prepared in which is a single bond.

[0259] The mass ratio (D5 / A1) of the aminoquinoline antioxidant (D5) to the isoprene rubber (A1) is preferably greater than 0.025. When the mass ratio (D5 / A1) is greater than 0.025, the effect of improving ozone resistance can be more sufficiently obtained. In addition, from the viewpoint of further improving ozone resistance, the mass ratio (D5 / A1) is preferably 0.03 or more. On the other hand, the upper limit of the mass ratio (D5 / A1) is not particularly limited, but from the viewpoint of better maintaining physical properties other than ozone resistance, it is preferably 0.1 or less.

[0260] The proportion of the aminoquinoline antioxidant (D5) in the antioxidant (D) is not particularly limited, but is preferably, for example, 50 mass% or more, which can further improve ozone resistance.

[0261] The mass ratio ((D1+D5) / A1) of the total of the phenylenediamine-based antioxidant (D1) and the aminoquinoline-based antioxidant (D5) to the isoprene-based rubber (A1) is preferably greater than 0.025. When the mass ratio ((D1+D5) / A1) is greater than 0.025, the effect of improving ozone resistance can be more sufficiently obtained. In addition, from the viewpoint of further improving ozone resistance, the mass ratio ((D1+D5) / A1) is preferably 0.03 or more. On the other hand, the upper limit of the mass ratio ((D1+D5) / A1) is not particularly limited, but from the viewpoint of better maintaining physical properties other than ozone resistance, it is preferably 0.1 or less.

[0262] The total proportion of the phenylenediamine-based antioxidant (D1) and the aminoquinoline-based antioxidant (D5) in the antioxidant (D) is not particularly limited, but is preferably, for example, 50% by mass or more, which can further improve ozone resistance.

[0263] Quinoline Antiaging Agent (D2) The antioxidant (D) preferably further contains a quinoline antioxidant (D2) (excluding the aminoquinoline antioxidant (D5) represented by the general formula (d5) above). The quinoline antioxidant (D2) is an antioxidant having a quinoline moiety or a derivative thereof (such as a dihydroquinoline moiety or a tetrahydroquinoline moiety). The quinoline antioxidant (D2) has the effect of improving the ozone resistance of the rubber composition. A rubber composition containing both the phenylenediamine antioxidant (D1) represented by the general formula (d1) above and / or the aminoquinoline antioxidant (D5) represented by the general formula (d5) above, and the quinoline antioxidant (D2), can further suppress the occurrence of cracks in tires.

[0264] The quinoline-based antioxidant (D2) preferably has a dihydroquinoline moiety, and more preferably has a 1,2-dihydroquinoline moiety. Specific examples of the quinoline-based antioxidant (D2) include a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline (antiaging agent TMDQ) and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline. The quinoline-based antioxidant (D2) preferably contains a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline (antiaging agent TMDQ). A quinoline-based antioxidant (D2) containing a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline is highly effective in improving the ozone resistance of a rubber composition and also has the advantage of being less likely to discolor the rubber composition. Therefore, a rubber composition containing a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline can further suppress the occurrence of cracks in tires and is also less susceptible to discoloration. Examples of the polymer of 2,2,4-trimethyl-1,2-dihydroquinoline include a dimer, trimer, and tetramer of 2,2,4-trimethyl-1,2-dihydroquinoline.

[0265] The proportion of the quinoline antioxidant (D2) in the antioxidant (D) is preferably 10% by mass or more and 50% by mass or less. Within this range, ozone resistance can be further improved. From the same viewpoint, the proportion is more preferably 15% by mass or more and more preferably 40% by mass or less.

[0266] -Amine-based Antiaging Agent (D3) of Formula (d3)- The antioxidant (D) can further be an amine-based antiaging agent represented by the following general formula (d3): [In the formula, R ３０１ and R ３０２ are each independently a monovalent saturated hydrocarbon group. It is preferable to include an amine-based antioxidant (D3) represented by the general formula (d3) (excluding the phenylenediamine-based antioxidant (D1) represented by the general formula (d1) above). The amine-based antioxidant (D3) represented by the general formula (d3) contains a phenylenediamine moiety, just like the general-purpose antioxidant N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (antiaging agent 6PPD), but differs from antioxidant 6PPD in that it does not contain a double bond outside the phenylenediamine moiety. The amine-based antioxidant (D3) represented by the general formula (d3) has the effect of improving the ozone resistance of the rubber composition.

[0267] In the above general formula (d3), R ３０１ and R ３０２ are each independently a monovalent saturated hydrocarbon group. ３０１ and R ３０２ may be the same or different, but from the viewpoint of synthesis, they are preferably the same.

[0268] The number of carbon atoms in the monovalent saturated hydrocarbon group is preferably 1 to 20, more preferably 3 to 10, and particularly preferably 6 or 7. When the number of carbon atoms in the saturated hydrocarbon group is 20 or less, the number of moles per unit mass increases, thereby enhancing the anti-aging effect and further improving the ozone resistance of the rubber composition. ３０１ and R ３０２ From the viewpoint of further improving the ozone resistance of the rubber composition, it is preferable that each of the groups independently represents a linear or cyclic monovalent saturated hydrocarbon group having 1 to 20 carbon atoms.

[0269] Examples of the monovalent saturated hydrocarbon group include an alkyl group and a cycloalkyl group. The alkyl group may be linear or branched, and the cycloalkyl group may further have an alkyl group or the like bonded thereto as a substituent. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a 1,2-dimethylbutyl group, a 1,3-dimethylbutyl group, a 2,3-dimethylbutyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, a 4-methylpentyl group, a 1,2-dimethylpentyl group, a 1,3-dimethylpentyl group, a 1,4-dimethylpentyl group, a 2,3-dimethylpentyl group, a 2,4-dimethylpentyl group, a 3,4-dimethylpentyl group, an n-hexyl group, a 1-methylhexyl group, a 2-methylhexyl group, various octyl groups, various decyl groups, and various dodecyl groups. Of these, a 1,4-dimethylpentyl group is preferred. Examples of the cycloalkyl group include a cyclopentyl group, a methylcyclopentyl group, a cyclohexyl group, a methylcyclohexyl group, a cycloheptyl group, and a cyclooctyl group, and among these, a cyclohexyl group is preferred.

[0270] Specific examples of the amine-based antioxidant (D3) represented by the general formula (d3) include N,N'-dicyclohexyl-p-phenylenediamine, etc. The amine-based antioxidant (D3) represented by the formula (d3) may be used alone or in combination of two or more.

[0271] The proportion of the amine-based antioxidant (D3) in the antioxidant (D) is preferably 0.1% by mass or more and 80% by mass or less. Within this range, ozone resistance can be further improved. From the same viewpoint, the proportion is more preferably 1% by mass or more and more preferably 70% by mass or less.

[0272] -Amine-based Antiaging Agent (D4) of Formula (d4)- The antioxidant (D) can further be an amine-based antiaging agent represented by the following general formula (d4): [In the formula, R ４０１ and R４０２ represents a phenyl group, and m4 represents an integer of 7 or more. The amine-based antioxidant (D4) represented by the general formula (d4) has a higher molecular weight than conventional antioxidants, and as shown in the formula (d4), it has a bridge moiety having a unique and relatively long chain length, i.e., "-NH-CH(CH ３ )-(CH ２ ) ｍ４ -CH(CH ３ )-NH-". It is believed that the high molecular weight and the presence of specific bridge moieties of the amine-based antiaging agent (D4) reduce the diffusion rate in the rubber composition, and migration to the rubber surface is further suppressed. Furthermore, the amine-based antiaging agent (D4) has a moiety composed of "-CH(CH ３ )-(CH ２ ) ｍ４ -CH(CH ３ One hydrogen atom is bonded to each of the two nitrogen atoms present at both ends of formula (d4)- (forming a so-called secondary amino group), and the presence of such bonds in the structure represented by formula (d4) is thought to contribute to the specific effect of improving ozone resistance (weather resistance).

[0273] In the above general formula (d4), R ４０１ and R ４０２ is a phenyl group. ４０１ and R ４０２ When is a phenyl group, the ozone resistance of the rubber composition can be further improved, and discoloration of the rubber composition can be more reliably prevented.

[0274] In the general formula (d4), m4 is an integer of at least 7. From the viewpoint of improving the ozone resistance of the rubber composition and preventing discoloration, m4 is preferably an integer of 8 to 16, and more preferably an integer of 10 to 14.

[0275] Examples of the amine-based antioxidant (D4) represented by general formula (d4) above include N,N'-bis(4-anilinophenyl)dodecane-2,11-diamine, N,N'-bis(4-anilinophenyl)tetradecane-2,13-diamine, N,N'-bis(4-anilinophenyl)hexadecane-2,15-diamine, N,N'-bis(4-anilinophenyl)octadecane-2,17-diamine, etc. Of these, N,N'-bis(4-anilinophenyl)tetradecane-2,13-diamine and N,N'-bis(4-anilinophenyl)octadecane-2,17-diamine are particularly preferred.

[0276] The proportion of the amine-based antioxidant (D4) in the antioxidant (D) is preferably 0.1% by mass or more and 80% by mass or less. Within this range, ozone resistance can be further improved. From the same viewpoint, the proportion is more preferably 1% by mass or more and more preferably 70% by mass or less.

[0277] -Other Antiaging Agent (D6)- The antioxidant (D) may or may not contain an antioxidant (D6) other than the phenylenediamine-based antioxidant (D1) of formula (d1), the quinoline-based antioxidant (D2), the amine-based antioxidant (D3) of formula (d3), the amine-based antioxidant (D4) of formula (d4), and the aminoquinoline-based antioxidant (D5) of formula (d5). Examples of the other antioxidant (D6) include N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) and N,N'-diphenyl-p-phenylenediamine (DPPD). Commercially available antioxidants can be used, including those manufactured by Ouchi Shinko Chemical Industry Co., Ltd., Sumitomo Chemical Co., Ltd., Seiko Chemical Co., Ltd., and Flexis. These other antioxidants (D6) may be used alone or in combination of two or more. However, in the present embodiment, it is preferred that the antioxidant (D) does not contain N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) among these. The proportion of the other antioxidant (D6) in the antioxidant (D) is preferably 0 to 20% by mass, more preferably 0 to 10% by mass.

[0278] (Silane Coupling Agent) When the rubber composition of this embodiment contains silica as the filler (C), in order to improve the effect of the silica, the rubber composition preferably contains a silane coupling agent. Examples of the silane coupling agent include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, Examples of such tetrasulfides include N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, and dimethoxymethylsilylpropyl benzothiazolyl tetrasulfide. As the silane coupling agent, commercially available products can be used, and examples of commercially available silane coupling agents that can be used include products from Evonik, Momentive, Shin-Etsu Silicones Co., Ltd., Dow Corning Toray Co., Ltd., Tokyo Chemical Industry Co., Ltd., and Azumax Co., Ltd. These silane coupling agents may be used alone or in combination of two or more.

[0279] The content of said silane coupling agent can be adjusted appropriately.For example, the content of said silane coupling agent is preferably 1 mass part or more, more preferably 2 mass parts or more, even more preferably 5 mass parts or more, and is preferably 20 mass parts or less, more preferably 15 mass parts or less, even more preferably 12 mass parts or less, and even more preferably 10 mass parts or less, relative to 100 mass parts of said silica.

[0280] (Styrene-Based Thermoplastic Elastomer) The rubber composition of this embodiment may contain a styrene-based thermoplastic elastomer (TPS). The styrene-based thermoplastic elastomer (TPS) has a styrene-based polymer block (hard segment) and a conjugated diene-based polymer block (soft segment), and the styrene-based polymer portion forms physical crosslinks to serve as crosslinking points, while the conjugated diene-based polymer block imparts rubber elasticity. The double bonds of the conjugated diene-based polymer block (soft segment) may be partially or completely hydrogenated. Note that, in this specification, the styrene-based thermoplastic elastomer (TPS) is not included in the rubber component (A). The content of the styrene-based thermoplastic elastomer (TPS) is preferably in the range of 1 to 30 parts by mass per 100 parts by mass of the rubber component (A).

[0281] Examples of the styrene-based thermoplastic elastomer (TPS) include styrene / butadiene / styrene (SBS) block copolymers, styrene / isoprene / styrene (SIS) block copolymers, styrene / butadiene / isoprene / styrene (SBIS) block copolymers, styrene / butadiene (SB) block copolymers, styrene / isoprene (SI) block copolymers, styrene / butadiene / isoprene (SBI) block copolymers, styrene / ethylene / butylene / styrene (SEBS) block copolymers, styrene / ethylene / propylene / styrene (SEPS) block copolymers, styrene / ethylene / ethylene / propylene / styrene (SEEPS) block copolymers, styrene / ethylene / butylene (SEB) block copolymers, styrene / ethylene / propylene (SEP) block copolymers, and styrene / ethylene / ethylene / propylene (SEEP) block copolymers.

[0282] (Rubber Crumb) The rubber composition of this embodiment may contain rubber crumb. The rubber crumb may be obtained by pulverizing used rubber products such as used tires and, if desired, removing reinforcing materials such as steel and fibers, dust, glass, sand, stones, etc., or by preparing a new vulcanized rubber composition for producing rubber crumb and pulverizing the pulverized rubber. For example, rubber crumb can be obtained from vulcanized rubber by the method described in "Rubber Chemistry and Technology." The process of pulverizing vulcanized rubber to obtain rubber crumb may involve mechanical treatment or low-temperature treatment. For example, in mechanical treatment, various crushing devices such as a cracker mill or a granulator can be used to mechanically crush the vulcanized rubber into fine particles. In low-temperature treatment, the finely chopped vulcanized rubber is frozen at a cryogenic temperature and then crushed into fine particles. A magnetic separator or the like can be used to remove steel, and an air separator or the like can be used to remove fibers. The rubber powder may be a commercially available product, such as those from Global Corporation or Nantong Huili Rubber Corporation. From the viewpoint of reducing the environmental impact, it is preferable to use rubber powder obtained by crushing used rubber products such as used tires. The rubber powder may be used alone or in combination of two or more types.

[0283] The composition of the rubber crumb is not particularly limited and depends on the composition of the vulcanized rubber from used rubber products (used tires) or the like that serve as the raw material. In one embodiment, the rubber crumb contains a rubber component, carbon black, silica, etc. The rubber component, carbon black, silica, etc. contained in the rubber crumb may be the same as or different from the rubber component, carbon black, silica, etc. that can be contained in the rubber composition of the present embodiment described above.

[0284] The rubber powder preferably has a volume average particle diameter of 1000 μm or less, more preferably 500 μm or less, even more preferably 200 μm or less, and even more preferably 100 μm or less. The smaller the volume average particle diameter of the rubber powder, the better, and there is no particular lower limit. In this specification, the volume average particle diameter is measured with a laser diffraction particle size distribution analyzer, for example, a "CAPA500" manufactured by Horiba, Ltd.

[0285] The rubber powder preferably has a 60-mesh sieve residue of less than 1% by mass, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less, with no particular lower limit. The rubber powder preferably has an 80-mesh sieve residue of less than 10% by mass, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less, with no particular lower limit. In this specification, the sieve residue is measured in accordance with ASTM D5644-01.

[0286] The rubber crumb has an acetone extractable content of preferably 12% by mass or less, more preferably 11% by mass or less, and even more preferably 10% by mass or less, and preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more. In this specification, the acetone extractable content in the rubber crumb refers to the acetone extractable content (%) determined by the acetone extraction method in accordance with JIS K6350.

[0287] The content of the rubber crumb is not particularly limited and can be adjusted appropriately depending on, for example, the target performance of the tire to which the composition is applied. For example, the content of the rubber crumb is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, and is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, more preferably 100 parts by mass or less, more preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less, relative to 100 parts by mass of the rubber component (A).

[0288] (Liquid Softener) The rubber composition of this embodiment may contain a liquid softener. Here, the "liquid softener" is a compounding agent that is liquid at 25°C (room temperature) and has the effect of softening the rubber composition. The liquid softener is not particularly limited, and examples thereof include oil and liquid polymer, among which oil is preferred. These liquid softeners may be used alone or in combination of two or more.

[0289] The oil is a general term for extender oils contained in rubber components and liquid oils added as compounding agents to rubber compositions. Examples include vegetable oils, process oils, oils obtained by recycling vegetable oils or process oils, and mixtures thereof. From the perspective of reducing environmental impact, vegetable oils and recycled oils are preferred. Examples of vegetable oils include palm oil, castor oil, cottonseed oil, soybean oil, linseed oil, rapeseed oil, coconut oil, pine oil, pine tar, tall oil, corn oil, rice oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil, and coconut oil. Examples of process oils include paraffin-based process oils, aromatic process oils, and naphthenic process oils. As the oil, commercially available products can be used, and examples of commercially available oils that can be used include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Oriso Co., Ltd., H&R Corporation, Toyokuni Oil Mills Co., Ltd., and Nisshin Oillio Group Co., Ltd. These oils may be used alone or in combination of two or more.

[0290] The liquid polymer is preferably a liquid diene-based polymer. Examples of the liquid diene-based polymer include liquid styrene-butadiene copolymer (liquid SBR), liquid polybutadiene (liquid BR), liquid polyisoprene (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), liquid styrene-butadiene-styrene block copolymer (liquid SBS block polymer), liquid styrene-isoprene-styrene block copolymer (liquid SIS block polymer), liquid polyfarnesene, and liquid farnesene-butadiene copolymer. These liquid polymers may be hydrogenated, or their terminals or main chains may be modified with functional groups (polar groups). These liquid polymers may be used alone or in combination of two or more.

[0291] The content of the liquid softener is not particularly limited and can be adjusted appropriately depending on, for example, the target performance of the tire to which it is applied, etc. For example, the content of the liquid softener is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 50 parts by mass or less, and even more preferably 30 parts by mass or less, relative to 100 parts by mass of the rubber component (A).

[0292] (Wax) The rubber composition of this embodiment may contain a wax. Examples of the wax include natural waxes such as plant waxes and animal waxes; petroleum waxes such as paraffin wax and microcrystalline wax; and synthetic waxes such as ethylene polymers and propylene polymers. Commercially available waxes can be used, and examples of commercially available waxes include products from Seiko Chemical Co., Ltd., Nippon Seiro Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., and the like. These waxes may be used alone or in combination of two or more.

[0293] The content of the wax is not particularly limited and can be appropriately adjusted depending on, for example, the target performance of the tire to which the rubber component (A) is applied. For example, the content of the wax is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, and even more preferably 4 parts by mass or less, relative to 100 parts by mass of the rubber component (A).

[0294] (Stearic Acid) The rubber composition of the present embodiment may contain stearic acid. Commercially available stearic acid products are available, including those from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Chiba Fatty Acid Co., Ltd., and the like. These commercially available stearic acid products may be used alone or in combination of two or more.

[0295] The content of stearic acid is not particularly limited and can be appropriately adjusted depending on, for example, the target performance of the tire to which the composition is applied, etc. For example, the content of stearic acid is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, per 100 parts by mass of the rubber component (A).

[0296] (Zinc Oxide) The rubber composition of this embodiment may contain zinc oxide (zinc white). The zinc oxide is preferably zinc oxide obtained by recycling. Commercially available zinc oxide can be used, and examples of commercially available zinc oxide include products from Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., Mitsui Mining & Smelting Co., Ltd., and Toho Zinc Co., Ltd. These commercially available zinc oxide products may be used alone or in combination of two or more. The zinc used for the zinc oxide may be not only zinc ores, but also zinc obtained from recycled zinc or zinc dross.

[0297] The content of the zinc oxide is not particularly limited and can be adjusted appropriately depending on, for example, the target performance of the tire to which the composition is applied, etc. For example, the content of the zinc oxide is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less, relative to 100 parts by mass of the rubber component (A).

[0298] (Sulfur) The rubber composition of this embodiment preferably contains sulfur. The sulfur may be derived from fossil resources, recycled resources, or sulfur obtained by processing biological resource-derived materials. From the perspective of reducing environmental impact, it is particularly preferable to use sulfur obtained from waste derived from biological resources. Examples of methods for obtaining sulfur from waste derived from biological resources include the method described in the aforementioned Japanese Patent Application No. 2022-140390. Furthermore, the sulfur may be powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, or the like, which are commonly used as crosslinking agents in the rubber industry. Commercially available sulfur products can be used, including those from Tsurumi Chemical Industry Co., Ltd., Hosoi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., and Flexis Corporation. These sulfurs may be used alone or in combination of two or more.

[0299] The sulfur content is not particularly limited and can be appropriately adjusted depending on, for example, the target performance of the tire to which the rubber component (A) is applied. For example, the sulfur content is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, still more preferably 0.8 parts by mass or more, still more preferably 1 part by mass or more, and is preferably 8 parts by mass or less, more preferably 5 parts by mass or less, and still more preferably 4 parts by mass or less, relative to 100 parts by mass of the rubber component (A).

[0300] (Vulcanization Accelerator) The rubber composition of this embodiment preferably contains a vulcanization accelerator. The vulcanization accelerator may be derived from fossil resources, renewable resources, or biological resources, but is preferably derived from biological resources from the viewpoint of reducing the environmental impact. Vulcanization accelerators derived from biological resources can be obtained, for example, by the method disclosed in JP 2005-139239 A. Examples of the vulcanization accelerator include sulfenamide vulcanization accelerators such as N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-oxyethylene-2-benzothiazolsulfenamide, and N,N'-diisopropyl-2-benzothiazolsulfenamide; 1,3-diphenylguanidine (DPG), 1,3-dibenzothiazolylsulfenamide, and the like. Examples of suitable vulcanization accelerators include guanidine-based vulcanization accelerators such as o-tolylguanidine and o-tolylbiguanidine; thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole (M) and di-2-benzothiazolyl disulfide (MBTS, DM); and thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrastearylthiuram disulfide, tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N). Commercially available vulcanization accelerators can be used, including those manufactured by Ouchi Shinko Chemical Industry Co., Ltd., Sumitomo Chemical Co., Ltd., and the like. These vulcanization accelerators may be used alone or in combination of two or more.

[0301] The content of the vulcanization accelerator is not particularly limited and can be adjusted appropriately depending on, for example, the target performance of the tire to which the vulcanization accelerator is applied. For example, the content of the vulcanization accelerator is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, still more preferably 1 part by mass or more, even more preferably 2 parts by mass or more, still more preferably 3 parts by mass or more, and is preferably 8 parts by mass or less, more preferably 6 parts by mass or less, still more preferably 5.5 parts by mass or less, and even more preferably 4 parts by mass or less, relative to 100 parts by mass of the rubber component (A).

[0302] (Cellulose Nanofiber) The rubber composition of this embodiment may contain cellulose nanofiber (CNF). The cellulose nanofiber can be blended into the rubber composition to reinforce the rubber composition. The cellulose nanofiber is preferably a modified cellulose nanofiber, which is a fine fiber made from modified cellulose. The fiber diameter of the cellulose nanofiber is not particularly limited, but is approximately 3 to 500 nm. The average fiber diameter and average fiber length of the cellulose nanofiber can be obtained by averaging the fiber diameters and fiber lengths obtained from the observation of each fiber using a scanning electron microscope (SEM), an atomic force microscope (AFM), or a transmission electron microscope (TEM). The cellulose nanofiber can be obtained by defibrating cellulose. The average fiber length and average fiber diameter of the fine fibers can be adjusted by oxidation treatment or defibration treatment.

[0303] The raw material for the cellulose nanofibers is not particularly limited as long as it contains cellulose, and examples thereof include plants (e.g., wood, bamboo, hemp, jute, kenaf, agricultural waste, cloth, pulp (softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), bleached kraft pulp (BKP), softwood unbleached sulfite pulp (NUSP), softwood bleached sulfite pulp (NBSP), thermomechanical pulp (TMP), recycled pulp, waste paper, etc.), animals (e.g., ascidians), algae, microorganisms (e.g., acetic acid bacteria (Acetobacter)), microbial products, etc. These cellulose raw materials may be used alone or in combination of two or more.

[0304] The content of the cellulose nanofibers is not particularly limited and can be adjusted appropriately depending on, for example, the target performance of the tire to which the rubber component (A) is applied. For example, the content of the cellulose nanofibers is preferably in the range of 1 to 100 parts by mass, more preferably in the range of 5 to 70 parts by mass, and even more preferably in the range of 10 to 40 parts by mass, per 100 parts by mass of the rubber component (A).

[0305] (Porous Cellulose Particles) The rubber composition of this embodiment may contain porous cellulose particles. The porous cellulose particles are preferably cellulose particles having a porous structure with a porosity of 75 to 95%, and by incorporating them into the rubber composition, performance on ice can be improved. When the porosity of the porous cellulose particles is 75% or more, the effect of improving performance on ice is excellent, and when the porosity is 95% or less, the strength of the particles can be increased. The porosity is more preferably 80 to 90%. The porosity of the porous cellulose particles can be calculated by measuring the volume of a certain mass of sample (i.e., porous cellulose particles) with a measuring cylinder, determining the bulk specific gravity, and using the following formula: Porosity (%) = {1 - [bulk specific gravity of sample (g / mL)] / [true specific gravity of sample (g / mL)]} × 100, where the true specific gravity of cellulose is 1.5.

[0306] The particle size of the porous cellulose particles is not particularly limited, but from the viewpoint of abrasion resistance, an average particle size of 1000 μm or less is preferred. The lower limit of the average particle size is not particularly limited, but it is preferably 5 μm or more. The average particle size is more preferably 100 to 800 μm, and even more preferably 200 to 800 μm. The porous cellulose particles are preferably spherical particles with a major axis / minor axis ratio of 1 to 2. The use of particles with such a spherical structure improves dispersibility in the rubber composition, contributing to improved performance on ice and the maintenance of abrasion resistance. The major axis / minor axis ratio is more preferably 1.0 to 1.5. The average particle size and major axis / minor axis ratio of the porous cellulose particles can be determined as follows. That is, porous cellulose particles are observed under a microscope to obtain an image, and this image is used to measure the long and short diameters of the particles (if the long and short diameters are the same, the length in a certain axis direction and the length in an axis direction perpendicular to it) for 100 particles, and the average particle size is obtained by calculating the average value, and the long diameter / short diameter ratio is obtained by averaging the values ​​obtained by dividing the long diameter by the short diameter.

[0307] The porous cellulose particles are commercially available from Rengo Co., Ltd. under the name "Viscopal" and are also described in JP-A Nos. 2001-323095 and 2004-115284, and can be suitably used.

[0308] The content of the porous cellulose particles is not particularly limited and can be appropriately adjusted depending on, for example, the target performance of the tire to which the rubber component (A) is applied, etc. For example, the content of the porous cellulose particles is preferably in the range of 0.3 to 20 parts by mass, more preferably in the range of 1 to 15 parts by mass, and even more preferably in the range of 3 to 15 parts by mass, per 100 parts by mass of the rubber component (A).

[0309] (Solid Particles) The rubber composition of this embodiment may contain solid particles. Blending the solid particles into the rubber composition can improve performance on ice. The solid particles preferably have an average particle diameter of 1 μm or more, preferably 1000 μm or less, and more preferably 300 μm or less. Examples of the solid particles include plant-derived powders obtained from plants, such as rice husks, walnut flour, and walnut shells; animal-derived powders obtained from animals, such as eggshells (eggshell powder) and bone powder; powders derived from natural minerals, such as whitebait; inorganic particles, such as graphite and zinc oxide whiskers; water-soluble metal salt particles, such as magnesium sulfate and metal salts of lignosulfonic acid; and non-metallic fibers, such as glass fibers. Of these, rice husks, walnut shells, eggshells, and whitebait are preferred.

[0310] The content of the solid fine particles is not particularly limited and can be appropriately adjusted depending on, for example, the target performance of the tire to which the rubber component (A) is applied, etc. For example, the content of the solid fine particles is preferably in the range of 0.3 to 20 parts by mass, more preferably in the range of 1 to 15 parts by mass, and even more preferably in the range of 3 to 15 parts by mass, per 100 parts by mass of the rubber component (A).

[0311] (Others) In addition to the above-mentioned components, the rubber composition of the present embodiment may further contain various additives commonly used in the rubber industry for tires, etc., such as organic peroxides. The content of these additives is not particularly limited and can be adjusted appropriately depending on, for example, the target performance of the tire to which the composition is applied. For example, the content is preferably in the range of 0.1 to 200 parts by mass per 100 parts by mass of the rubber component (A).

[0312] (Method for Producing Rubber Composition) The method for producing the rubber composition of the present embodiment is not particularly limited, but the rubber composition can be produced, for example, by blending various components appropriately selected as necessary with the rubber component (A), followed by kneading, heating, extruding, etc. The obtained rubber composition can be vulcanized to produce a vulcanized rubber.

[0313] The conditions for the kneading are not particularly limited, and various conditions such as the input volume of the kneading device, the rotation speed of the rotor, the ram pressure, the kneading temperature, the kneading time, the type of kneading device, etc. can be appropriately selected depending on the purpose. Examples of the kneading device include a Banbury mixer, an intermix, a kneader, a roll, etc. that are usually used for kneading rubber compositions.

[0314] The conditions for the heat-in are not particularly limited, and various conditions such as the heat-in temperature, heat-in time, and heat-in device can be appropriately selected depending on the purpose. Examples of the heat-in device include a heat-in roll mill typically used for heat-in of rubber compositions.

[0315] The extrusion conditions are not particularly limited, and various conditions such as extrusion time, extrusion speed, extrusion device, and extrusion temperature can be appropriately selected depending on the purpose. Examples of the extrusion device include an extruder typically used for extruding rubber compositions. The extrusion temperature can be appropriately determined.

[0316] The vulcanization apparatus, method, conditions, etc. are not particularly limited and can be appropriately selected depending on the purpose. Examples of apparatuses for vulcanization include molding vulcanizers using molds used for vulcanizing rubber compositions. The vulcanization temperature is, for example, about 100 to 190°C.

[0317] <Inner Layer Rubber (Rubber Composition for Inner Layer Rubber)> The inner layer rubber of the tire of the present invention can be produced using a rubber composition (rubber composition for inner layer rubber) containing the rubber component (A'), the antioxidant (D'), and any other components. Hereinafter, various components that may be contained in the rubber composition for the inner layer rubber (hereinafter sometimes simply referred to as the "rubber composition" or the "rubber composition of the present embodiment") will be described.

[0318] (Rubber Component (A')) The rubber composition (rubber composition for the inner layer rubber) of this embodiment contains a rubber component (A'), which provides rubber elasticity to the composition. The rubber component (A') is preferably a diene rubber, and the rubber component (A') is more preferably selected from natural rubber (NR), synthetic isoprene rubber (IR), butadiene rubber (BR), and styrene-butadiene rubber (SBR). When the rubber component of the inner layer rubber contains at least one selected from the group consisting of natural rubber (NR), synthetic isoprene rubber (IR), butadiene rubber (BR), and styrene-butadiene rubber (SBR), the rubber elasticity of the inner layer rubber is excellent and durability is improved. Furthermore, when the rubber component of the inner layer rubber contains at least one selected from the group consisting of natural rubber (NR), synthetic isoprene rubber (IR), butadiene rubber (BR), and styrene-butadiene rubber (SBR), the effects of the present invention (such as the effect of improving ozone resistance) are more likely to be evident. The content of diene rubbers such as natural rubber (NR), synthetic isoprene rubber (IR), butadiene rubber (BR), and styrene-butadiene rubber (SBR) in the rubber component of the inner layer rubber is preferably 80% by mass or more, more preferably 90% by mass or more, and may even be 100% by mass. The rubber component (A') of the inner layer rubber may be used alone or in combination of two or more.

[0319] The rubber component (A') of the inner layer rubber may be the same as or different from the rubber component (A) of the outer layer rubber described above.

[0320] (Antioxidant (D')) The rubber composition of the present embodiment (rubber composition for the inner layer rubber) contains an antioxidant (D'). The antioxidant (D') has the effect of preventing aging of the rubber composition and a tire using the same.

[0321] Examples of the antioxidant (D') include the phenylenediamine-based antioxidant (D1) represented by general formula (d1), quinoline-based antioxidant (D2), amine-based antioxidant (D3) represented by general formula (d3), amine-based antioxidant (D4) represented by general formula (d4), aminoquinoline-based antioxidant (D5) represented by general formula (d5), other antioxidants (D6), etc., which are already described for the outer layer rubber. One type of antioxidant (D') may be used alone, or two or more types may be used in combination.

[0322] The content of the antioxidant (D') is preferably 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component (A'). When the content of the antioxidant (D') in the rubber composition is 0.5 parts by mass or more per 100 parts by mass of the rubber component (A'), the antioxidant (D') is sufficiently transferred to the outer layer rubber, the ozone resistance of the outer layer rubber is sufficiently ensured, and the occurrence of cracks can be further suppressed. Furthermore, when the content of the antioxidant (D') in the rubber composition is 10 parts by mass or less per 100 parts by mass of the rubber component (A'), sufficiently good abrasion resistance can be maintained.

[0323] The rubber composition for the inner layer rubber may contain other components as needed. These other components may be selected appropriately from a variety of components commonly used in the rubber industry, such as fillers (silica, carbon black, calcium carbonate, etc.), silane coupling agents, softeners, waxes, surfactants, organic acids (stearic acid, etc.), zinc oxide (zinc white), vulcanization accelerators, vulcanizing agents (sulfur, etc.), and other compounding agents, within a range that does not impair the object of the present invention. Commercially available products may be suitably used as these compounding agents.

[0324] <Manufacture of Tire> Depending on the type of tire to be applied, the tire may be obtained by molding an unvulcanized rubber composition and then vulcanizing it, or by molding a semi-vulcanized rubber that has been subjected to a pre-vulcanization step or the like and then further vulcanizing it. The tire is preferably a pneumatic tire, and the gas to be filled into the pneumatic tire may be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium.

[0325] The present invention will be explained in more detail below by way of examples, but the present invention is not limited to the following examples and can be modified as appropriate within the scope of the present invention.

[0326] <Preparation of Rubber Composition> Rubber compositions of Examples and Comparative Examples were prepared by blending and kneading the components according to the formulations shown in Table 1. The sustainable material ratio was calculated as an integer by calculating the total mass ratio of the components derived from biological resources (biomass resources) and the components derived from recycled resources (recycled resources) for each rubber composition. The results are shown in Table 1.

[0327] (Evaluation of Abrasion Resistance) The rubber composition is vulcanized to obtain a vulcanized rubber test piece. The obtained vulcanized rubber test piece is measured for abrasion at room temperature at a slip rate of 15% using a Lambourn abrasion tester manufactured by Ueshima Seisakusho in accordance with JIS K 6264-2:2005, with sandpaper attached to the grinding wheel. The measured value is indexed, with the reciprocal of the abrasion amount in Comparative Example 1 set as 100. The index values ​​are classified according to the following criteria. The higher the index value, the better the abrasion resistance. The results are shown in Table 1. A: More than 120 B: More than 100 but not more than 120 C: Not more than 100

[0328] (Evaluation of ozone resistance) A dynamic ozone degradation test (a test in which repeated strain is applied) is conducted in accordance with ISO 1431 (JIS K 6259), and the sample is observed at 20x magnification using a microscope. The observed samples are ranked according to the size and depth of cracks and classified according to the following criteria (1 to 5), with smaller numbers indicating better ozone resistance. The results are shown in Table 1. (Ranking by crack size and depth) 1: Not visible to the naked eye but visible with a 10x magnifying glass. 2: Visible to the naked eye. 3: Deep and relatively large cracks (less than 1 mm). 4: Deep and large cracks (1 mm or more but less than 3 mm). 5: Cracks of 3 mm or more or likely to cause breakage.

[0329]

[0330] *1 Natural rubber: TSR #20, SP value = 8.20 (cal / cm ３ ) １／２ *2 Low Tg modified SBR: Hydrocarbyloxysilane compound modified styrene-butadiene rubber synthesized by the following method, Tg = -65 ° C., SP value = 8.65 (cal / cm ３ ) １／２ * 3 Medium Tg modified SBR1: SBR obtained using butyl lithium as an initiator, styrene-butadiene rubber whose terminals are modified with N-(1,3-dimethylbutylidene)-3-triethoxysilyl-1-propanamine, Tg = -38 ° C., SP value = 8.95 (cal / cm ３ ) １／２ * 4 Medium Tg modified SBR2: Based on the manufacturing method of polymer K of JP 2007-70642 A, a hexamethyleneimine-modified styrene-butadiene rubber having a bound styrene content of 35% by mass and a vinyl bond content of 21% in the butadiene portion, produced using a blend of styrene and butadiene monomers in a changed ratio, Tg = -38 ° C., SP value = 8.95 (cal / cm ３ ) １／２* 5 Silica: Tosoh Silica Corporation, trade name "Nipsil AQ" * 6 Virgin carbon black: Asahi Carbon Co., Ltd., trade name "#80" * 7 Recycled carbon black: Obtained by thermal decomposition of vulcanized rubber products containing carbon black, ash content = 17% by mass * 8 Resin component: Hydrogenated C ５ based resin, manufactured by Eastman, trade name "Registered Trademark Impera E1780", softening point = 130°C, weight average molecular weight (Mw) = 909 g / mol, SP value = 8.35 (cal / cm ３ ) １／２ * 9 Silane coupling agent: Evonik Degussa, trade name "Si75" * 10 Antioxidant-1: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) * 11 Antioxidant-2: N-phenyl-N'-(1-methylheptyl)-p-phenylenediamine (8PPD) * 12 Antioxidant-3: Aminoquinoline-based antioxidant represented by the following structural formula (d5-1) * 13 Wax: Manufactured by Nippon Seiro Co., Ltd., trade name "Ozoace 0701" * 14 Vulcanization accelerator A: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Nocceler DM-P" * 15 Vulcanization accelerator B: Manufactured by Sanshin Chemical Industry Co., Ltd., trade name "Suncerer NS-G"

[0331] <Method for synthesizing low-Tg modified SBR (*2)> A cyclohexane solution of 1,3-butadiene and a cyclohexane solution of styrene were added to a dried, nitrogen-purged 800 mL pressure-resistant glass vessel so that the total weight of the mixture was 67.5 g of 1,3-butadiene and 7.5 g of styrene, and 0.6 mmol of 2,2-ditetrahydrofurylpropane and 0.8 mmol of n-butyllithium were added. Polymerization was then carried out at 50°C for 1.5 hours. To the polymerization reaction system, where the polymerization conversion rate was nearly 100%, 0.72 mmol of N,N-bis(trimethylsilyl)-3-[diethoxy(methyl)silyl]propylamine was added as a modifier, and the modification reaction was carried out at 50°C for 30 minutes. The reaction was then terminated by adding 2 mL of a 5% by mass solution of 2,6-di-t-butyl-p-cresol (BHT) in isopropanol, and the mixture was dried in the usual manner to obtain modified SBR. In measuring the microstructure of the obtained modified SBR, the amount of bound styrene was 10% by mass, and the glass transition temperature (Tg) was -65°C.

[0332] From Table 1, it can be seen that the examples provide good results without using 6PPD, which may have an impact on the environment.

[0333] According to the present invention, it is possible to provide a tire that has low environmental impact, excellent wear resistance, and excellent ozone resistance.

[0334] 1: Bead portion, 2: Sidewall portion, 3: Outer layer rubber, 4: Inner layer rubber, 5: Tread portion, 6: Carcass, 7: Metal or fiber cord layer, 8: Bead core, 9: Base rubber, 10: Tread undercushion rubber, 11: Reinforcing layer of metal or fiber cord layer

Claims

1. A tire having a tread portion, an outer layer rubber constituting the tread surface of the tread portion, a layer of metal or fiber cords arranged radially inward of the outer layer rubber, and an inner layer rubber located between the outer layer rubber and the layer of metal or fiber cords, wherein the outer layer rubber contains a rubber component (A), a resin component (B), a filler (C), and an antioxidant (D), and the antioxidant (D) is a compound represented by the following general formula (d1): [In the formula, R １０１ and R １０２ are each independently an alkyl group or an aryl group having 7 or more carbon atoms, and R １０１ and R １０２ wherein at least one of the groups is an alkyl group having 7 or more carbon atoms, and a phenylenediamine-based antioxidant (D1) represented by the following general formula (d5): [In the formula, is a single bond or a double bond, R ５０１ and R ５０２ are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a phenyl group; R ５０３ , R ５０４ , R ５０５ , R ５０６ , R ５０７ , R ５０８ , R ５０９ and R ５１０ are each independently hydrogen or an alkyl group having 1 to 12 carbon atoms.], and the inner layer rubber contains a rubber component (A') and an antioxidant (D').

2. The tire according to claim 1, wherein the rubber component (A) in the outer layer rubber includes an isoprene-based rubber (A1).

3. The tire according to claim 2, wherein in the outer layer rubber, the mass ratio (B / A1) of the resin component (B) to the isoprene-based rubber (A1) is 0.5 or more, and the mass ratio (D1 / A1) of the phenylenediamine-based antioxidant (D1) to the isoprene-based rubber (A1) is greater than 0.025, and in the inner layer rubber, the content of the antioxidant (D') is 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component (A').

4. The tire according to claim 2, wherein in the outer layer rubber, the rubber component (A) further contains a styrene-butadiene rubber (A2).

5. The tire according to claim 1, wherein the rubber component (A) in the outer layer rubber comprises a modified polymer modified with a modifier having a functional group containing a nitrogen atom and an alkoxy group.

6. The tire according to claim 4, wherein the styrene-butadiene rubber (A2) has a glass transition temperature of less than -40°C.

7. The tire according to claim 2, wherein the content of the isoprene-based rubber (A1) in the outer layer rubber is 1 to 40 parts by mass per 100 parts by mass of the rubber component (A).

8. In the outer layer rubber, the difference in SP value between the isoprene-based rubber (A1) and the resin component (B) is 0.50 (cal / cm ３ ) １／２ and the difference in SP value from the styrene-butadiene rubber (A2) is 0.3 (cal / cm ３ ) １／２ The tire according to claim 4, wherein 9. The resin component (B) is a hydrogenated terpene resin, a hydrogenated C ５ based resin, hydrogenated C ５ -C ９ 2. The tire according to claim 1, wherein the olefin-based resin is at least one selected from the group consisting of a olefin-based resin and a hydrogenated dicyclopentadiene-based resin.

10. The tire according to claim 1, wherein the filler (C) contains recycled carbon black, and the recycled carbon black has an ash content of 20% by mass or less.

11. R in the general formula (d1) １０１ and R １０２ The tire of claim 1 , wherein the other of the groups is a phenyl group.

12. R in the general formula (d1) １０１ and R １０２ 2. The tire according to claim 1, wherein at least one of the alkyl groups has a carbon number of 7 or 8.

13. The tire according to claim 1, wherein the mass ratio (B / D) of the resin component (B) to the antioxidant (D) in the outer layer rubber is 2 or more and 40 or less.

14. The tire according to claim 1, wherein the outer layer rubber contains the antioxidant (D) in an amount of 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component (A), the antioxidant (D) further contains a quinoline-based antioxidant (D2) (excluding the aminoquinoline-based antioxidant (D5) represented by the general formula (d5) above), and the proportion of the quinoline-based antioxidant (D2) in the antioxidant (D) is 10% by mass or more and 50% by mass or less.

15. In the outer layer rubber, the antioxidant (D) further contains a compound represented by the following general formula (d3): [In the formula, R ３０１ and R ３０２ are each independently a monovalent saturated hydrocarbon group. (However, the phenylenediamine-based antioxidant (D1) represented by the general formula (d1) is excluded.), and a proportion of the amine-based antioxidant (D3) in the antioxidant (D) is 0.1% by mass or more and 80% by mass or less.

16. In the outer layer rubber, the antioxidant (D) further contains a compound represented by the following general formula (d4): [In the formula, R ４０１ and R ４０２ represents a phenyl group, and m4 represents an integer of 7 or greater.], and a proportion of the amine-based antioxidant (D4) in the antioxidant (D) is 0.1% by mass or greater and 80% by mass or less.

Images