Rubber composition and tire

Abstract

To provide a rubber composition which is excellent in low rolling resistance, low-temperature characteristics and steering stability and also has an increased ratio of sustainable materials.SOLUTION: The rubber composition according to the present invention contains a rubber component and resins. The rubber composition contains, as the resins, a rosin resin and at least one selected from the group consisting of terpene resins and terpene-aromatic compound resins in a total amount of 1-50 pts.mass based on 100 pts.mass of the rubber component. The rubber component contains an isoprene skeleton rubber and a styrene-butadiene rubber. The styrene-butadiene rubber has a glass transition temperature lower than -40°C.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] From the viewpoint of improving vehicle safety, various studies have been conducted to improve the braking performance (low-temperature characteristics) and driving performance of tires not only on normal road surfaces but also in low-temperature environments such as icy and snowy road surfaces. For example, a technology is known in which a rubber composition containing aromatic oils together with rubber components such as natural rubber (NR) and butadiene rubber (BR) is used as tread rubber in order to improve performance on wet and snowy roads (Patent Document 1). Also, in order to improve grip performance on wet / snowy roads, a technology is known in which a rubber composition obtained by compounding 5 to 50 parts by mass of a C5 resin with 100 parts by mass of a rubber component containing a total of 30% by mass or more of natural rubber and / or polyisoprene rubber is used as a tread rubber (Patent Document 2).

[0003] However, with the techniques disclosed in Patent Documents 1 and 2, it was difficult to achieve a high level of both improved low-temperature characteristics and reduced rolling resistance of the tire (hereinafter referred to as "low rolling resistance").

[0004] On the other hand, apart from the above-mentioned wet performance, wear resistance, and low rolling resistance, from the perspective of social sustainability, there is also a demand for the use of so-called sustainable materials, such as materials derived from biological resources (biomass resources) and materials derived from renewable resources (recycled resources), for the various components used in tires, and there is also a desire to develop technology to increase the usage rate of sustainable materials (hereinafter sometimes referred to as the "proportion of sustainable materials"). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-269884 [Patent Document 1] JP 2006-241358 A Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to provide a rubber composition which is excellent in low rolling resistance, low-temperature properties and handling stability, and also has an improved ratio of sustainable materials. Another object of the present invention is to provide a tire that has low rolling resistance, excellent low-temperature properties and handling stability, and also has an improved ratio of sustainable materials. [Means for solving the problem]

[0007] The present inventors have conducted intensive research into a rubber composition containing a rubber component and a resin in order to solve the above problems. They have found that by incorporating specific amounts of at least one selected from the group consisting of terpene resins and terpene-aromatic compound resins, and a rosin resin, as the resin, it is possible to realize excellent low-temperature characteristics and steering stability even when materials derived from fossil resources currently used are replaced with sustainable materials, and further, by suppressing the resin content within a specific range and incorporating a styrene-butadiene rubber having a glass transition temperature of less than -40°C, the dispersibility of the filler is improved, and the fuel efficiency performance, low-temperature characteristics, and steering stability of a tire to which the rubber composition is applied can be well maintained.

[0008] That is, the gist of the present invention is as follows. [1] A rubber composition comprising a rubber component and a resin, The resin contains at least one selected from the group consisting of a terpene resin and a terpene-aromatic compound resin, and a rosin resin in a total amount of 1 to 50 parts by mass per 100 parts by mass of the rubber component, The rubber component contains an isoprene skeleton rubber and a styrene-butadiene rubber, The rubber composition, wherein the styrene-butadiene rubber has a glass transition temperature of less than -40°C. The rubber composition of the present invention described in [1] above is excellent in low rolling resistance, low-temperature properties and handling stability, and can also improve the proportion of sustainable materials.

[0009] [2] The resin has an SP value difference of 0.6 (cal / cm) from that of the isoprene skeleton rubber. 3 ) 1 / 2 and / or a weight average molecular weight in terms of polystyrene of 500 to 1300 g / mol. The rubber composition of the present invention described in [2] above can further improve low rolling resistance, handling stability and low temperature properties.

[0010] [3] The rubber composition according to [1] or [2], wherein the content of the isoprene skeleton rubber is 1 to 80 parts by mass per 100 parts by mass of the rubber component. The rubber composition of the present invention described in [3] above can achieve an improved balance between low rolling resistance, low-temperature properties, and handling stability.

[0011] [4] The rubber composition according to any one of [1] to [3], wherein the amount of the isoprene skeleton rubber is 1 to 40 parts by mass per 100 parts by mass of the rubber component. The rubber composition of the present invention described in [4] above can achieve an improved balance between low rolling resistance, low-temperature properties, and handling stability.

[0012] [5] The rubber composition according to [1] or [2], characterized in that the styrene-butadiene rubber is modified with a modifier having a functional group containing a nitrogen atom and an alkoxy group. The rubber composition of the present invention described in [5] above can achieve a balance of low rolling resistance, low-temperature properties and handling stability, and can further improve workability.

[0013] [6] A tire comprising the rubber composition according to [1] or [2]. The tire of the present invention described in [6] above has low rolling resistance, excellent low-temperature characteristics and handling stability, and the proportion of sustainable materials can also be improved. Excellent in. Effect of the Invention

[0014] According to the present invention, it is possible to provide a rubber composition which has low rolling resistance, excellent low-temperature properties and handling stability, and also has an improved ratio of sustainable materials. Moreover, according to the present invention, it is possible to provide a tire which has low rolling resistance, excellent low-temperature characteristics and handling stability, and which also has an improved ratio of sustainable materials. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described. The compounds described in this specification may be derived partially or entirely from fossil resources, from biological resources such as plant resources, or from recycled resources such as used tires, or may be derived from a mixture of two or more of fossil resources, biological resources, and recycled resources.

[0016] In addition, in this specification, the "proportion of sustainable materials" refers to the total mass ratio of components derived from biological resources (biomass resources) and components derived from renewable resources (recycled resources) in the target material.

[0017] In this specification, the biological resources (biomass resources) refer to carbon-neutral organic resources derived from living organisms, and include, for example, those 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 are resources other than fossil resources (petroleum, coal, natural gas, etc.). The biological resources may be edible or non-edible, but are preferably non-edible from the viewpoint of not competing with food and of effective resource utilization.

[0018] 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 waste, 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 ... Examples of the biological resources include crops (corn, wheat, rice, rice husks, rice bran, old rice, potatoes, buckwheat, cassava, sago palm, sugarcane, etc.), bagasse (i.e., the residue after squeezing juice from sugarcane), soybeans, soybean pulp, essential oils (pine oil, orange oil, eucalyptus oil, etc.), pulp black liquor, algae, etc. The biological resources may be processed (i.e., biological resource-derived substances). Examples of the processing methods include biological processing methods that utilize the functions of microorganisms, plants, animals, and tissue cultures thereof; chemical processing methods that utilize acids, alkalis, catalysts, thermal energy, light energy, etc.; physical processing methods such as micronization, compression, microwave processing, and electromagnetic wave processing; and the like. The biological resources may also be extracted and refined from the biological resources or biological resources that have been processed (i.e., biological resource-derived substances). For example, sugars, proteins, amino acids, fatty acids, fatty acid esters, etc., purified from the biological resources can 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, and among these, valine, leucine, isoleucine, arginine, and phenylalanine are preferred.The amino acid may be either an L-amino acid or a D-amino acid, but L-amino acids are preferred from the viewpoints of abundance in nature and ease of availability. The fatty acids include butyric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, etc., which are derived from biological resources. The fatty acid esters include modified products of vegetable oils, animal oils, and fats and oils derived from biological resources. These biological resources may be contaminated with various materials and impurities.

[0019] 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.

[0020] <Rubber composition>

[0021] The configuration of the rubber composition of the present invention will be described below. The rubber composition of the present invention includes a rubber component and a resin, The resin contains at least one selected from the group consisting of a terpene resin and a terpene-aromatic compound resin, and a rosin resin in a total amount of 1 to 50 parts by mass per 100 parts by mass of the rubber component, The rubber component contains an isoprene skeleton rubber and a styrene-butadiene rubber, The styrene-butadiene rubber is characterized by having a glass transition temperature of less than -40°C.

[0022] In the rubber composition of the present invention, by blending a rosin-based resin together with at least one resin selected from the group consisting of a terpene-based resin and a terpene-aromatic compound-based resin as the resin, it is possible to improve the balance between low rolling resistance, low temperature properties, and handling stability. However, simply blending the resin reduces the fuel economy and wear resistance of a tire to which the rubber composition is applied, and if the content of the resin exceeds 50 parts by mass per 100 parts by mass of the rubber component, the low rolling resistance of a tire to which the rubber composition is applied deteriorates. In contrast, in the rubber composition for tires of the present invention, the content of the resin is set to 50 parts by mass or less per 100 parts by mass of the rubber component, and a styrene-butadiene rubber having a glass transition temperature of less than -40°C is blended, thereby improving the dispersibility of the filler in the rubber composition and complementing the balance between the low rolling resistance, low temperature characteristics, and handling stability of the rubber composition.

[0023] (Rubber component) The rubber composition of the present invention includes a rubber component that provides rubber elasticity to the composition. The rubber component includes an isoprene-based rubber and a styrene-butadiene rubber. Isoprene-based rubber The isoprene skeleton rubber is a rubber having an isoprene unit as a main skeleton, and specific examples thereof include natural rubber (NR), synthetic isoprene rubber (IR), modified natural rubber (modified NR), modified natural rubber (modified NR), modified synthetic isoprene rubber (modified IR), etc. As the natural rubber (NR), for example, RSS#3, TSR20 (e.g., SIR20 and STR20), etc., which are common in the tire industry, can be used. The rubber component contains an isoprene skeleton rubber, which can increase the breaking strength of the rubber composition, thereby reducing the rolling resistance of a tire using the rubber composition, improving fuel economy, and improving the wear resistance of the tire.

[0024] The origin of the natural rubber (NR) is not particularly limited, and examples thereof include those derived from Hevea brasiliensis, guayule, and Russian dandelion. The synthetic isoprene rubber (IR) is not particularly limited, and examples thereof include those commonly used in the tire industry, 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 modified IR include epoxidized synthetic isoprene rubber, hydrogenated synthetic isoprene rubber, and grafted synthetic isoprene rubber. These isoprene-based rubbers may be used alone or in combination of two or more. Among these, NR is preferred as the isoprene-based rubber.

[0025] The content of the isoprene skeleton rubber is preferably 1 to 80 parts by mass, more preferably 1 to 65 parts by mass, in 100 parts by mass of the rubber component. When the content of the isoprene skeleton rubber is 1 to 65 parts by mass, in 100 parts by mass of the rubber component, the fuel economy performance and low temperature performance of a tire to which the rubber composition is applied can be further improved. When the content of the isoprene skeleton rubber is 1 to 65 parts by mass, in 100 parts by mass of the rubber component, the fuel economy performance and low temperature properties of a tire to which the rubber composition is applied can be further improved. In addition, from the viewpoint of increasing the compounding effect of the isoprene skeleton rubber, the content of the isoprene skeleton rubber is more preferably 10 parts by mass or more, in 100 parts by mass of the rubber component.

[0026] Furthermore, the isoprene-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. In order to set the sustainability rate of the isoprene-based rubber 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 renewable 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 renewable resources, a copolymer of a monomer derived from biological resources and a monomer derived from renewable resources, or a copolymer of a monomer derived from biological resources and / or a monomer derived from renewable resources and a monomer derived from a fossil resource (petroleum, etc.).

[0027] Styrene-butadiene rubber The styrene-butadiene rubber (SBR) has a glass transition temperature of less than -40°C, preferably less than -45°C, more preferably less than -50°C, and preferably higher than -90°C. If the glass transition temperature of the styrene-butadiene rubber is less than -40°C, the fuel economy and wear resistance of a tire to which the rubber composition is applied can be sufficiently improved. In addition, the styrene-butadiene rubber having a glass transition temperature higher than -90°C is easy to synthesize.

[0028] The content of the styrene-butadiene rubber is preferably 20 to 99 parts by mass, more preferably 30 to 99 parts by mass, and further preferably 35 to 99 parts by mass, in 100 parts by mass of the rubber component. When the content of the styrene-butadiene rubber is 60 to 99 parts by mass in 100 parts by mass of the rubber component, the fuel economy performance and wet grip performance of a tire to which the rubber composition for tires is applied can be further improved.

[0029] The difference in SP value between the isoprene skeleton rubber and the styrene-butadiene rubber 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 isoprene skeleton rubber and the styrene-butadiene rubber is 0.3 (cal / cm 3 )1 / 2 In the above cases, the isoprene skeleton rubber and the styrene-butadiene rubber tend to become incompatible.

[0030] The styrene-butadiene rubber preferably has a bound styrene content of less than 15% by mass. The bound styrene content of the styrene-butadiene rubber means the ratio of styrene units contained in the styrene-butadiene rubber. When the bound styrene content of the styrene-butadiene rubber is less than 15% by mass, the glass transition temperature is likely to be low. The bound styrene content of the styrene-butadiene rubber is more preferably 14% by mass or less, more preferably 13% by mass or less, and even more preferably 12% by mass or less. In addition, from the viewpoint of the wear resistance performance of a tire to which the rubber composition is applied, the bound styrene content of the styrene-butadiene rubber is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 8% by mass or more. The amount of bound styrene in the styrene-butadiene rubber can be adjusted by the amount of monomer used in polymerization of the styrene-butadiene rubber, the degree of polymerization, and the like.

[0031] The styrene-butadiene rubber is preferably modified with a modifier having a functional group containing a nitrogen atom and an alkoxy group. When the styrene-butadiene rubber is modified with a modifier having a functional group containing a nitrogen atom and an alkoxy group, the balance of wet grip performance, fuel economy, and wear resistance of a tire to which the rubber composition is applied is further improved, and in particular, the fuel economy and wear resistance can be further improved. The modifying agent having a functional group containing a nitrogen atom and an alkoxy group is a general term for modifying agents having at least one functional group containing a nitrogen atom and at least one alkoxy group. The functional group containing a nitrogen atom is preferably selected from the following: The functional group is 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, a non-cyclic secondary amino group, an onium salt residue of a non-cyclic secondary amine, an isocyanuric acid triester residue, a cyclic tertiary amino group, a non-cyclic tertiary amino group, a nitrile group, a pyridine residue, an onium salt residue of a cyclic tertiary amine, and an onium salt residue of a non-cyclic tertiary amine, and is a monovalent hydrocarbon group having 1 to 30 carbon atoms and containing a straight-chain, branched, alicyclic, or aromatic ring, 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.

[0032] -First preferred embodiment of modified styrene-butadiene rubber- The styrene-butadiene rubber (SBR) is preferably 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. 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 (particularly silica) becomes particularly large.

[0033] The modified site of the styrene-butadiene rubber may be the molecular terminal as described above, but may also be the main chain. Styrene-butadiene rubber having modified molecular terminals can be produced, for example, by reacting various modifiers with the terminals of a styrene-butadiene copolymer having active terminals according to the methods described in WO 2003 / 046020 and JP 2007-217562 A. In a preferred embodiment, the styrene-butadiene rubber having modified molecular terminals can be produced by reacting an aminoalkoxysilane compound with the terminals of a styrene-butadiene copolymer having active terminals 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, according to the methods described in WO 2003 / 046020 and JP 2007-217562 A.

[0034] The carboxylic acid partial ester of a polyhydric alcohol means an ester of a polyhydric alcohol and a carboxylic acid, and a partial ester having one or more hydroxyl groups. Specifically, an ester of a sugar or modified sugar having 4 or more carbon atoms and a fatty acid is preferably used. More preferred examples of this ester include (1) a fatty acid partial ester of a polyhydric alcohol, particularly a partial ester (which may be a monoester, diester, or triester) of a saturated higher fatty acid or an unsaturated higher fatty acid having 10 to 20 carbon atoms and a polyhydric alcohol, and (2) an ester compound in which 1 to 3 partial esters of a polycarboxylic acid and a higher alcohol are bonded to a polyhydric alcohol. The polyhydric alcohol used as a raw material for the partial ester is preferably a saccharide having at least three hydroxyl groups and having 5 or 6 carbon atoms (which may or may not be hydrogenated), glycol, polyhydroxy compound, etc. The raw material fatty acid is preferably a saturated or unsaturated fatty acid having 10 to 20 carbon atoms, such as stearic acid, lauric acid, or palmitic acid. Among the fatty acid partial esters of polyhydric alcohols, sorbitan fatty acid esters are preferred, and specific examples thereof include sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, and sorbitan trioleate.

[0035] The aminoalkoxysilane compound is not particularly limited, but is preferably an aminoalkoxysilane compound represented by the following general formula (i). R11 a -Si-(OR 12 ) 4-a (i)

[0036] 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 12 If there are multiple, each OR 12 may be the same or different, and the molecule does not contain any active protons.

[0037] As the aminoalkoxysilane compound, an aminoalkoxysilane compound represented by the following general formula (ii) is also preferred. [ka]

[0038] 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). A 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. R 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, may be the same or different. R 22is 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, either 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. R 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. R 24 represents 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 when n4 is 2 or greater, may be the same or different. As the hydrolyzable group in the hydrolyzable group-containing primary or secondary amino group, a trimethylsilyl group or a tert-butyldimethylsilyl group is preferred, and a trimethylsilyl group is particularly preferred.

[0039] The aminoalkoxysilane compound represented by the above general formula (ii) is preferably an aminoalkoxysilane compound represented by the following general formula (iii). [ka]

[0040] In the general formula (iii), p1+p2+p3=2 (wherein p2 is an integer of 1 or 2, and p1 and p3 are integers of 0 or 1). A 2 is NRa (Ra is a monovalent hydrocarbon group, a hydrolyzable group, or a nitrogen-containing organic group). R 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. R 26is 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. R 27 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. R 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.

[0041] 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). [ka]

[0042] 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). R 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. R 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. R 34 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 q1 is 2, may be the same or different. R 35represents 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 greater, may be the same or different.

[0043] [ka]

[0044] In the general formula (v), r1+r2=3 (wherein r1 is an integer of 1 to 3, and r2 is an integer of 0 to 2). R 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. R 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 dimethylsilylaminoethyl 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 may be the same or different when r1 is 2 or greater. R 38 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 when r2 is 2, may be the same or different. A specific example of the aminoalkoxysilane compound represented by the general formula (v) is N-(1,3-dimethylbutylidene)-3-triethoxysilyl-1-propaneamine.

[0045] 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). [ka]

[0046] 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. R 41 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. R 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. Here, TMS represents a trimethylsilyl group (the same applies hereinafter).

[0047] [ka]

[0048] 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. R 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.

[0049] The aminoalkoxysilane compound represented by the above general formula (ii) is also preferably an aminoalkoxysilane compound represented by the following general formula (viii) or (ix). [ka]

[0050] 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). R 46is 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. R 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.

[0051] [ka]

[0052] In general formula (ix), X is a halogen atom. R 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. R 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 linked to form a divalent organic group. R 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. R 50 and R 51 As the hydrolyzable group, a hydrolyzable group is preferable, and as the hydrolyzable group, a trimethylsilyl group or a tert-butyldimethylsilyl group is preferable, and a trimethylsilyl group is particularly preferable.

[0053] 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). [ka] [ka] [ka] [ka]

[0054] In the general formulas (x) to (xiii), the symbols U and V each represent an integer of 0 to 2 and satisfying U+V=2. R in general formulas (x) to (xiii) 54 ~ 92 may be the same or different and are a monovalent or divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent or divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. In the general formula (xiii), α and β are integers of 0 to 5.

[0055] 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. Furthermore, among the compounds satisfying the 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.

[0056] -Modified styrene-butadiene rubber according to a second preferred embodiment- It is also preferable that the styrene-butadiene rubber (SBR) is modified with a coupling agent represented by the following general formula (I), in which case the fuel economy and wear resistance of a tire using the rubber composition can be further improved. [ka]

[0057] In the above general formula (I), R 1 , R 2 and R 3 each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms. R 4 , R 5 , R 6 , R 7 and R 9 each independently represents an alkyl group having 1 to 20 carbon atoms. R 8 and R 11 each independently represents an alkylene group having 1 to 20 carbon atoms. R 10 represents an alkyl group or a trialkylsilyl group having 1 to 20 carbon atoms. m represents an integer of 1 to 3; p represents 1 or 2. R 1 ~R 11 When multiple , m and p are present, they are independent of each other. 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, the hydrocarbon group represented by A in the general formula (I) includes saturated, unsaturated, aliphatic, and aromatic hydrocarbon groups. Examples of the organic group that does not have an active hydrogen include organic groups that do not have a functional group that has an active hydrogen, such as a hydroxyl group (-OH), a secondary amino group (>NH), a primary amino group (-NH2), or a sulfhydryl group (-SH).

[0058] The styrene-butadiene rubber modified with the coupling agent represented by the above general formula (I) has a weight average molecular weight (Mw) of 20×10 4 ~300×10 4 The molecular weight of the modified styrene-butadiene rubber is 200×10 4 ~500×10 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.

[0059] In general, polymers having branches tend to have smaller molecular size compared to linear polymers of 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 of the same absolute molecular weight. In other words, the larger the degree of branching of a polymer, the smaller the shrinkage factor (g') tends to be. In this embodiment, intrinsic viscosity is used as an index of molecular size, and linear polymers have an intrinsic viscosity [η] = -3.883M 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 calculated when the absolute molecular weight is 100 x 10 4 ~200×10 4The average value of the shrinkage factor (g') at this time is the shrinkage factor (g') of the modified styrene-butadiene rubber. Here, "branch" is formed by directly or indirectly bonding one polymer to another polymer. Also, "degree of branching" is the number of polymers that are directly or indirectly bonded to one branch. For example, when five styrene-butadiene copolymer chains described later are bonded to each other indirectly via coupling residues described later, the degree of branching is 5. Note that the coupling residue is a structural unit of the modified styrene-butadiene rubber 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 later with a coupling agent. Also, 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 later 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 equal to or less than 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') in this range, the processability of the rubber composition is improved. Since the shrinkage factor (g') tends to depend on the degree of branching, for example, the shrinkage factor (g') can be controlled using the degree of branching as an index. Specifically, when a modified styrene-butadiene rubber has a degree of branching 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 degree of branching of 8, its shrinkage factor (g') tends to be 0.45 or more and 0.59 or less.

[0060] The styrene-butadiene rubber modified by the coupling agent represented by the general formula (I) preferably has a branch and a branching degree of 5 or more. 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 branching includes a branch in which 5 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 5 or more and the branching includes a branch in which 5 or more styrene-butadiene copolymer chains are bonded to one coupling residue, the contraction factor (g') can be more reliably made 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'). Moreover, the modified styrene-butadiene rubber has branches, and more preferably has a branching degree of 6 or more. Moreover, the modified styrene-butadiene rubber has one or more coupling residues and a styrene-butadiene copolymer chain bonded to the coupling residue, and further preferably includes a branch in which six or more of the 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 branch includes a branch in which six or more styrene-butadiene copolymer chains are bonded to one coupling residue, the shrinkage factor (g') can be set to 0.63 or less. Furthermore, the modified styrene-butadiene rubber has branches, and the degree of branching is more preferably 7 or more, and even more preferably 8 or more. The upper limit of the degree of branching is not particularly limited, but is preferably 18 or less. The modified styrene-butadiene rubber has one or more coupling residues and a styrene-butadiene copolymer chain bonded to the coupling residue, and further, it is more preferable that the above-mentioned branches include a branch in which 7 or more styrene-butadiene copolymer chains are bonded to one coupling residue, and it is particularly preferable that the above-mentioned branches include a branch in which 8 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 8 or more and the branch includes a branch in which 8 or more styrene-butadiene copolymer chains are bonded to one coupling residue, the shrinkage factor (g') can be made 0.59 or less.

[0061] At least one end of the styrene-butadiene copolymer chain is preferably 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, the one silicon atom may constitute an alkoxysilyl group or silanol group having 1 to 20 carbon atoms.

[0062] 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 wear resistance, the Mooney viscosity measured at 100°C is preferably 20 to 100, more preferably 30 to 80.

[0063] The weight average molecular weight (Mw) of the modified styrene-butadiene rubber is preferably 20×10 4 More than 300 x 10 4More preferably, it is 50×10 or less. 4 More preferably, it is 64×10 4 More preferably, it is 80×10 4 The weight average molecular weight is preferably 250×10 4 or less, and more preferably 180×10 4 More preferably, it is 150×10 or less. 4 The weight average molecular weight is 20×10 4 When the weight average molecular weight is 300×10 or more, the low loss property and the 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.

[0064] The modified styrene-butadiene rubber has a molecular weight of 200×10 based on the total amount (100% by mass) of the modified styrene-butadiene rubber. 4 More than 500 x 10 4 It is preferable that the modified styrene-butadiene rubber (hereinafter also referred to as "specific high molecular weight component") is 0.25 mass% or more and 30 mass% or less. When the content of the specific high molecular weight component is 0.25 mass% or more and 30 mass% or less, the low loss property and wear resistance performance of the rubber composition can be sufficiently improved. The modified styrene-butadiene rubber contains the specific high molecular weight component preferably at 1.0 mass% or more, more preferably at 1.4 mass% or more, even more preferably at 1.75 mass% or more, even more preferably at 2.0 mass% or more, particularly preferably at 2.15 mass% or more, and extremely preferably at 2.5 mass% or more. In addition, the modified styrene-butadiene rubber contains the specific high molecular weight component preferably at 28 mass% or less, more preferably at 25 mass% or less, even more preferably at 20 mass% or less, and even more preferably at 18 mass% or less. In this specification, the "molecular weight" of the rubber component is the standard polystyrene equivalent molecular weight 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 in such a range, it is preferable to control the reaction conditions in the polymerization step and the reaction step described later. For example, in the polymerization step, the amount of an organic monolithium compound used as a polymerization initiator described later may be adjusted. In addition, in the polymerization step, in both the continuous and batch polymerization modes, a method having a residence time distribution is used, that is, the time distribution of the propagation reaction is expanded.

[0065] In the modified styrene-butadiene rubber, the molecular weight distribution (Mw / Mn) represented by 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 is good.

[0066] 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, 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").

[0067] The polymerization step is preferably a polymerization by a propagation reaction due to a living anionic polymerization reaction, which makes it possible to obtain a styrene-butadiene copolymer having an active terminal and a modified styrene-butadiene rubber with a high modification rate. The styrene-butadiene copolymer is obtained by copolymerizing 1,3-butadiene and styrene.

[0068] The amount of the organic monolithium compound used as a polymerization initiator is preferably determined according to 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 used is related to the degree of polymerization, that is, the number average molecular weight and / or the weight average molecular weight. Therefore, in order to increase the molecular weight, it is good to adjust the amount of polymerization initiator to decrease, and in order to decrease the molecular weight, it is good to adjust the amount of polymerization initiator to increase. The organic monolithium compound is preferably an alkyllithium compound from the viewpoint 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 the alkyllithium compound 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 viewpoint 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.

[0069] In the polymerization step, examples of the polymerization reaction mode include a batch polymerization mode and a continuous polymerization mode. In the continuous mode, one or more connected reactors can be used. For the continuous mode, for example, a tank type or a tube type reactor equipped with a stirrer is used. In the continuous mode, preferably, a monomer, 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. For the batch mode, for example, a tank type reactor equipped with a stirrer is used. In the batch mode, preferably, a monomer, an inert solvent, and a polymerization initiator are fed, and if necessary, a monomer is continuously or intermittently added 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 time.

[0070] 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 examples of the hydrocarbon solvent 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. Before being subjected to the polymerization reaction, impurities such as allenes and acetylenes are treated with an organometallic compound, which tends to obtain a styrene-butadiene copolymer having a high concentration of active ends, and a modified styrene-butadiene rubber with a high modification rate is preferably obtained.

[0071] In the polymerization step, a polar compound may be added. By adding the polar compound, styrene can be randomly copolymerized with 1,3-butadiene, and the polar compound tends to be usable as a vinylizing agent for controlling the microstructure of the 1,3-butadiene portion. Examples of the polar compounds 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.

[0072] 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. By keeping the temperature within such a range, there is a tendency that the amount of the coupling agent reacting with the active terminals after the completion of the polymerization can be sufficiently ensured.

[0073] The amount of bound butadiene in the styrene-butadiene copolymer or modified styrene-butadiene rubber is not particularly limited, but is preferably from 40% by mass to 100% by mass, and more preferably from 55% by mass to 80% by mass. Furthermore, 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 mass% and not more than 60 mass%, and more preferably 20 mass% or more and 45 mass% or less. When the bound butadiene amount and the bound styrene amount are within the above ranges, the low loss property and the wear resistance of the rubber composition can be further improved. The amount of bound styrene can be measured by ultraviolet absorption of the phenyl group, from which the amount of bound butadiene can also be calculated.

[0074] 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% to 75 mol%, more preferably 20 mol% to 65 mol%. When the amount of vinyl bonds is within the above range, the low loss property and wear resistance of the rubber composition can be further improved. For modified styrene-butadiene rubber, the amount of vinyl bonds (1,2-bonds) in the butadiene bond units can be determined by Hampton's method [RR Hampton, Analytical Chemistry, 21, 923 (1949)].

[0075] The alkoxysilyl group of the coupling agent represented by the above general formula (I) tends to react with, for example, the active terminal of the styrene-butadiene copolymer, dissociating the alkoxylithium, and forming a bond between the end of the styrene-butadiene copolymer chain and the silicon of the coupling residue. The number of alkoxysilyl groups of the coupling residue is the total number of SiO R of one molecule of the coupling agent minus the number of SiO R reduced by the reaction. In addition, the azasilacycle group of the coupling agent forms a >N-Li bond and a bond between the end of the styrene-butadiene copolymer and the silicon of the coupling residue. The >N-Li bond tends to easily become >NH and LiOH due to water or the like during finishing. In addition, the alkoxysilyl group remaining unreacted in the coupling agent tends to easily become a silanol (Si-OH group) due to water or the like during finishing.

[0076] The reaction temperature in the reaction step is preferably the same as the polymerization temperature of the styrene-butadiene copolymer, more preferably from 0° C. to 120° C., and even more preferably from 50° C. to 100° C. The temperature change from the end of the polymerization step to the addition of the coupling agent is preferably 10° C. or less, more preferably 5° C. or less. The reaction time in the reaction step is preferably 10 seconds or more, more preferably 30 seconds or more. From the viewpoint of the coupling rate, the time from the end of the polymerization step to the start of the reaction step is preferably shorter, and more preferably within 5 minutes. The mixing in the reaction step may be performed by mechanical stirring, stirring with a static mixer, or the like. When the polymerization step is a continuous process, it is preferable that the reaction step is also a continuous process. The reactor used in the reaction step may be, for example, a tank type or a tube type equipped with a stirrer. The coupling agent may be diluted with an inert solvent and continuously fed to the reactor. When the polymerization step is a batch process, the coupling agent may be added to the polymerization reactor, or may be transferred to another reactor to carry out the reaction step.

[0077] In the general formula (I), A is preferably represented by any one of the following general formulae (II) to (V). When A is represented by any one of the general formulae (II) to (V), a modified styrene-butadiene rubber having better performance can be obtained.

[0078] [ka] 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.

[0079] [ka] 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.

[0080] [ka] 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.

[0081] [ka] 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.

[0082] B in the general formulas (II) to (V) 1 , B 2 , B 4 , B 5 With regard to the above, examples of the hydrocarbon group having 1 to 20 carbon atoms include an alkylene group having 1 to 20 carbon atoms.

[0083] 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), k represents 0, and in the general formula (II) or (III), a represents an integer of 2 to 10. More preferably, in said general formula (I), A is represented by said general formula (II), k represents 0, and in said general formula (II), a represents 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, and the like. Among these, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine and tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane are particularly preferred.

[0084] The amount of the compound represented by the general formula (I) added as the coupling agent can be adjusted so that the mole number of the styrene-butadiene copolymer to the mole number of the coupling agent reacts at a desired stoichiometric ratio, which tends to achieve a desired branching degree. The specific mole number of the polymerization initiator is preferably 5.0 times or more, more preferably 6.0 times or more, relative to the mole number of the coupling agent. In this case, in the 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, more preferably an integer of 6 to 10.

[0085] In order to obtain the modified styrene-butadiene rubber having the specific polymer component, the molecular weight distribution (Mw / Mn) of the styrene-butadiene copolymer is preferably 1.5 to 2.5, more preferably 1.8 to 2.2. The modified styrene-butadiene rubber obtained is preferably one in which a single peak is detected in the molecular weight curve by GPC. When the peak molecular weight of the modified styrene-butadiene rubber by GPC is Mp1 and the peak molecular weight of the styrene-butadiene copolymer is Mp2, it is preferable that the following formula is satisfied. (Mp1 / Mp2)<1.8×10-12×(Mp2-120×10 4 ) 2 +2 Mp2 is 20 x 10 4 Over 80×10 4 Below, Mp1 is 30 x 10 4 Over 150 x 10 4 The following is more preferred: Mp1 and Mp2 are determined by the method described in the Examples below.

[0086] The modification rate of the modified styrene-butadiene rubber is preferably 30% by mass or more, more preferably 50% by mass or more, and further preferably 70% by mass or more. When the modification rate is 30% by mass or more, the low loss property and the wear resistance of the rubber composition can be further improved.

[0087] After the reaction step, a deactivator, neutralizer, etc. may be added to the copolymer solution as necessary. Examples of deactivators include, but are not limited to, water; alcohols such as methanol, ethanol, isopropanol, etc. Examples of 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 10 being the main carbon atom); aqueous solutions of inorganic acids, and carbon dioxide gas. In addition, 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.

[0088] The modified styrene-butadiene rubber can be obtained from the polymer solution by a known method, for example, a method of separating the solvent by steam stripping or the like, filtering the polymer, and then dehydrating and drying the polymer to obtain the polymer, a method of concentrating the polymer in a flashing tank and then devolatilizing the polymer with a vent extruder or the like, and a method of directly devolatilizing the polymer with a drum dryer or the like.

[0089] 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). [ka]

[0090] 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 ~100×10 4 The 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 produced by reacting a styrene-butadiene copolymer with a coupling agent. R 12 , R 13 and R 14 each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms. R 15 and R 18each independently represents an alkyl group having 1 to 20 carbon atoms. R 16 , R 19 , and R 20 each independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. R 17 and R 21 each independently represents an alkylene group having 1 to 20 carbon atoms. R 22 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. m and x each represent an integer of 1 to 3, provided that x≦m; p represents 1 or 2; y represents an integer of 1 to 3, provided that y≦(p+1); and z represents an integer of 1 or 2. D and R when there are multiple 12 ~R 22 , m, p, x, y, and z are each independent and may be the same or different. In addition, i represents an integer from 0 to 6, j represents an integer from 0 to 6, k represents an integer from 0 to 6, (i+j+k) is an integer from 3 to 10, and ((x×i)+(y×j)+(z×k)) is an integer from 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 organic groups having no functional groups having active hydrogen, such as a hydroxyl group (-OH), a secondary amino group (>NH), a primary amino group (-NH2), and a sulfhydryl group (-SH).

[0091] In the above general formula (VI), A is preferably represented by any one of the above general formulas (II) to (V). When A is represented by any one of the general formulas (II) to (V), the low loss property and wear resistance of the rubber composition can be further improved.

[0092] -Third preferred embodiment of modified styrene-butadiene rubber- It is also preferable that at least one end of the styrene-butadiene rubber (SBR) is modified with a modifying agent containing a compound (alkoxysilane) represented by the following general formula (1). [ka]

[0093] By using, as the rubber component, a styrene-butadiene rubber modified with a modifier containing a compound represented by the above general formula (1) containing an oligosiloxane and a tertiary amino group, which are filler affinity functional groups, the dispersibility of a filler such as silica can be improved. As a result, the rubber composition of the present invention has improved dispersibility of the filler, and therefore the low loss property is greatly improved, and the rolling resistance of a tire to which the rubber composition is applied can be reduced, thereby improving fuel efficiency.

[0094] 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 each independently represents an alkylene group having 1 to 20 carbon atoms; and n is an integer of 2 to 4.

[0095] Specifically, in formula (1), R 1 ~R 4 may each independently be a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, 1 ~R 4 When 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, the R1 ~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.

[0096] 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, R 1 ~R 4 It may be substituted with the substituents as described above. In addition, the above R 5 ~R 8 If is not an alkyl group but a hydrolyzable substituent, NR 5 R 6 and N.R. 7 R 8 The bond can be hydrolyzed to NH in the presence of moisture, adversely affecting the processability of the polymer.

[0097] More specifically, in the compound represented by the formula (1), R 1 ~R 4 is a methyl group or an ethyl group, R 5 ~R 8 can be an alkyl group having 1 to 10 carbon atoms.

[0098] The amino group in the compound represented by the formula (1), i.e., NR 5 R 6 and N.R. 7 R 8 is preferably a tertiary amino group. The tertiary amino group provides the compound represented by formula (1) with better processability when used as a modifying agent. In addition, the above R 5 ~R 8When a protecting group for protecting the amino group is bonded to the end of the polymer or when hydrogen is bonded to the end of the polymer, it may be difficult to realize the effect of the compound represented by formula (1). When hydrogen is bonded, the anion reacts with hydrogen during the modification process and loses reactivity, making the modification reaction itself impossible, and when a protecting group is bonded, the modification reaction takes place, but in the state bonded to the polymer end, it is deprotected by hydrolysis during post-processing to become a primary or secondary amino group, and the deprotected primary or secondary amino group may cause the compound to become highly viscous during subsequent blending, which may cause a decrease in processability.

[0099] In addition, L in the compound represented by the formula (1) 1 and L 2 each independently represents a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms. More specifically, L 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.

[0100] L in the compound represented by formula (1) 1 and L 2 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 processing steps, and the secondary amino group generated at this time is likely to be washed away by water during the post-processing, and 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. Considering the improvement effect due to the length of the bond between Si and N, the above L 1 and L 2 More preferably, each independently represents 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 R first 1~R 4 It may be substituted with the substituents as described above.

[0101] The compound represented by the 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 more excellent low loss properties to be achieved. [ka]

[0102] The compound represented by the formula (1) has an alkoxysilane structure that bonds with the active end of the styrene-butadiene copolymer, while the Si-O-Si structure and three or more amino groups bonded to the end show affinity for fillers such as silica, and thus can promote the bonding between the filler and the modified styrene-butadiene rubber compared to conventional modifiers containing one amino group in the molecule. In addition, the degree of bonding of the active end of the styrene-butadiene copolymer is uniform, and when the change in molecular weight distribution before and after coupling is observed, the molecular weight distribution after coupling is not larger than before and remains constant. 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, and the dispersibility of the filler can be increased, thereby improving the processability of the rubber composition. These effects make it possible to improve the fuel efficiency and wet grip performance in a well-balanced manner, particularly when the rubber composition is applied to tires.

[0103] The compound represented by the formula (1) can be produced through a condensation reaction represented by the following reaction scheme. [ka]

[0104] 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 may be identical to any one of the following:

[0105] The reaction of the reaction scheme proceeds in the presence of an acid, and the acid can be any acid that is generally used in condensation reactions 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, reaction temperature, etc.

[0106] The styrene-butadiene rubber modified by the 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, the tensile properties and viscoelasticity may be reduced when applied to a rubber composition. Considering the remarkable effect of improving the 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.

[0107] 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). In this case, 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, calculating the sum of these molecular weights, and dividing by n, and the weight average molecular weight (Mw) represents the molecular weight distribution of a 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 a polystyrene-equivalent molecular weight analyzed by gel permeation chromatography (GPC).

[0108] The modified styrene-butadiene rubber satisfies the above-mentioned molecular weight distribution conditions, and may have a number average molecular weight (Mn) of 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 may 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. When 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, the tensile properties may be deteriorated when applied to a rubber composition. When the weight average molecular weight (Mw) is more than 4,000,000 g / mol or the number average molecular weight (Mn) is more than 2,000,000 g / mol, the processability of the modified styrene-butadiene rubber is deteriorated, the workability of the rubber composition is deteriorated, kneading becomes difficult, and it may be difficult to sufficiently improve the physical properties of the rubber composition. More specifically, when the modified styrene-butadiene rubber satisfies the conditions of weight average molecular weight (Mw) and number average molecular weight (Mn) as well as the molecular weight distribution, when it is applied to a rubber composition, it can improve the viscoelasticity and processability of the rubber composition in a well-balanced manner.

[0109] The modified styrene-butadiene rubber has a vinyl bond content in the butadiene portion of preferably 5% or more, more preferably 10% or more, and more preferably 60% or less. By setting the vinyl bond content in the butadiene portion within the above range, the glass transition temperature can be adjusted to an appropriate range.

[0110] The modified styrene-butadiene rubber may have a Mooney viscosity (MV) at 100° C. of 40 to 140, specifically 60 to 100. When the modified styrene-butadiene rubber has a Mooney viscosity in the above range, it can exhibit better processability. The Mooney viscosity can be measured using a Mooney viscometer, for example, Monsanto's MV2000E, with a large rotor at 100° C. and a rotor speed of 2±0.02 rpm. 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, and the platen is operated to measure.

[0111] 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 to which the rubber composition is applied can achieve both low fuel consumption performance and wet grip performance at a higher level. [ka]

[0112] 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. In addition, in formula (2), R 12 represents a single bond; an alkylene group having 1 to 20 carbon atoms which is substituted or unsubstituted; a cycloalkylene group having 5 to 20 carbon atoms which is substituted or unsubstituted; or an arylene group having 5 to 20 carbon atoms which is substituted or unsubstituted, 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. In addition, in formula (2), R 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), m is an integer of 1 to 5, R 13 At least one of the functional groups represented by the following general formula (2a) or (2b) is a functional group represented by the following general formula (2a) or (2b). When m is an integer of 2 to 5, a plurality of R 13 may be the same or different from each other.

[0113] [ka]

[0114] In the above general formula (2a), R 14 represents an alkylene group having 1 to 20 carbon atoms, which is substituted or unsubstituted; a cycloalkylene group having 5 to 20 carbon atoms, which is substituted or unsubstituted; or an arylene group having 6 to 20 carbon atoms, which is substituted or unsubstituted, 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. In addition, in formula (2a), R 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 unsubstituted or substituted with an aryl group having 6 to 20 carbon atoms. In addition, in formula (2a), R 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.

[0115] [ka]

[0116] In the above general formula (2b), R 18 represents an alkylene group having 1 to 20 carbon atoms, which is substituted or unsubstituted; a cycloalkylene group having 5 to 20 carbon atoms, which is substituted or unsubstituted; or an arylene group having 6 to 20 carbon atoms, which is substituted or unsubstituted, 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. In addition, in formula (2b), R 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.

[0117] In addition, in the compound represented by the above 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 general formula (2b), and in the above general formula (2a), R 14 is an unsubstituted alkylene group having 1 to 10 carbon atoms, R 15 and R 16 are each independently an unsubstituted alkylene group having 1 to 10 carbon atoms, and R 17is 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, 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.

[0118] More specifically, the compound represented by the above general formula (2) can be the compounds represented by the following structural formulas (2-1) to (2-3). [ka]

[0119] In addition, when the styrene-butadiene copolymer is modified with a modifying agent containing the compound represented by the above 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.

[0120] Rubber components other than isoprene-based rubber and styrene-butadiene rubber The rubber component may contain rubber components other than the isoprene skeleton rubber and the styrene-butadiene rubber (hereinafter, sometimes referred to as "other rubber components"). The other rubber components are preferably the rubber derived from biological resources and the rubber derived from recycled resources.

[0121] 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, still more preferably 90 mol% or more, particularly preferably 95 mol% or more, and may be 100 mol%. Furthermore, the proportion of monomer components derived from recycled resources in 100 mol% of 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, still more preferably 90 mol% or more, particularly preferably 95 mol% or more, and may be 100 mol%.

[0122] The other rubber components are components that contribute to crosslinking, and usually have 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 million or less, more preferably 2 million or less, more preferably 1.5 million or less, and even more preferably 1.3 million or less. The weight average molecular weight (Mw) of the rubber component can be determined, for example, by converting the measured value into that of standard polystyrene using a gel permeation chromatograph (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0123] The other rubber component may be a diene rubber, and the diene rubber is preferably a butadiene rubber, where the butadiene rubber refers to a rubber containing a unit derived from butadiene as a monomer unit.

[0124] Examples of the butadiene rubber (BR) include high cis content butadiene rubber, low cis content butadiene rubber, and butadiene rubber containing syndiotactic polybutadiene crystals. Commercially available products can be used as the butadiene rubber (BR), and examples of commercially available butadiene rubbers include products from UBE Elastomers Co., Ltd., ENEOS Materials Corporation, Asahi Kasei Co., Ltd., and Zeon Corporation. These butadiene rubbers may be used alone or in combination of two or more.

[0125] 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. In order to make the sustainability rate of the butadiene-based rubber fall within the above range, for example, a polymer synthesized using butadiene derived from biological resources, butadiene derived from renewable resources, aromatic vinyl compounds derived from biological resources (e.g., styrene derived from biological resources), and aromatic vinyl compounds derived from renewable resources (e.g., styrene derived from renewable resources) as monomer components may be used. In this case, the synthesized polymer may be a homopolymer of a monomer derived from biological resources, a homopolymer of a monomer derived from renewable resources, a copolymer of a monomer derived from biological resources and a monomer derived from renewable resources, or a copolymer of a monomer derived from biological resources and / or a monomer derived from renewable resources and a monomer derived from a fossil resource (petroleum, etc.). In addition, the butadiene rubber (B-BR) derived from biological resources (biomass resources) and aromatic vinyl compound-butadiene copolymer rubber derived from biological resources (e.g., styrene-butadiene rubber (B-SBR) derived from biological resources (biomass resources)) include not only rubber obtained by polymerizing butadiene, etc. according to a conventional method, but also rubber obtained by reactions or enzyme reactions caused by microorganisms, plants, animals, and tissue cultures thereof (hereinafter also referred to as "microorganisms, etc.").

[0126] In order to set the sustainability rate of the entire rubber component within the above range, it is preferable to use natural rubber (NR) as the rubber component or a polymer synthesized using monomer components derived from biological resources or monomer components derived from recycled resources as monomer components.

[0127] Generally, materials for rubber compositions for tires (rubber and its monomers, fillers, resins, etc.) require large-scale manufacturing equipment for their production, and are therefore usually produced in large factories in specific regions, and a lot of energy is required for the storage and transportation of raw materials and products. In contrast, materials derived from biological resources (biomass resources) are derived from agricultural products, forests, etc. in each region, and can be produced on a small scale by fermentation of microorganisms and catalytic reactions, so by utilizing products and waste from each region, the energy required for the transportation and storage of raw materials can be reduced, and further the energy required for the transportation and storage of the produced materials to tire factories can also be reduced, which is environmentally friendly. In addition, materials derived from regenerated resources (recycled resources) can be obtained, for example, by dismantling and pyrolyzing used tires to extract materials that constitute tires, 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 materials for rubber compositions for tires can be obtained from various wastes and used items. In this way, by using sustainable materials (materials derived from biological resources or materials derived from recycled resources), it is possible to reduce the overall environmental load in 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 (LCC) incurred over the entire life cycle, and reducing the amount of fossil resources used.

[0128] In addition, when producing the rubber composition, the ratio of the monomer components derived from biological resources, the monomer components derived from renewable resources, and the monomer components derived from fossil resources can be appropriately selected according to 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), and the monomer components derived from biological resources, the monomer components derived from renewable resources, and the monomer components derived from fossil resources can be polymerized to obtain rubber derived from sustainable materials (materials derived from biological resources or materials derived from renewable resources) having performance equivalent to that of conventional synthetic rubber. When using monomer components derived from renewable resources, it may be difficult to separate them from monomer components derived from fossil resources due to the manufacturing process of the monomer. In that case, the impact on the environment can be evaluated by adopting the concept of mass balance.

[0129] The other rubber components may include diene rubbers such as acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), styrene-isoprene-butadiene copolymer rubber (SIBR), etc., in addition to the above-mentioned butadiene rubber (BR). These rubber components may be used alone or in combination of two or more.

[0130] The other rubber components may be modified to introduce functional groups that interact with fillers such as carbon black and silica. Examples of the 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 alone or in combination of two or more. 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.

[0131] The functional group can be introduced, for example, by reacting a compound (modifier) ​​having the functional group with the rubber component. The compound (modifier) ​​having a functional group is a modified functional group having an interactive property with a filler such as silica or carbon black, and includes any of a nitrogen-containing functional group, a silicon-containing functional group, and an oxygen-containing functional group. Examples of the nitrogen-containing functional group include an amino group-containing compound, and examples of the silicon-containing functional group include silicon halide and hydrocarbyloxysilane compounds, and examples of the oxygen-containing functional group include an alkoxy group-containing compound, an alkylene oxide group-containing compound, and a trialkylsilyloxy group-containing compound. More specifically, examples of the compounds include those described in WO2016 / 194316 and WO2019 / 117256. These modifying agents may be used alone or in combination of two or more.

[0132] The rubber derived from sustainable materials (materials derived from biological resources or materials derived from renewable resources) can be produced in the same manner as conventional synthetic rubber derived from fossil resources, for example, by using monomer components derived from biological resources or monomer components derived from renewable resources, and, if necessary, monomer components derived from fossil resources. The rubber derived from sustainable materials (particularly rubber derived from biological resources) can also be obtained by reactions with microorganisms or enzyme reactions.

[0133] Regarding the method for preparing rubber derived from biological resources from the above-mentioned biological resources, for example, the method described in JP 2022-179158 A can be used. For example, by using butadiene obtained from biological resources as a monomer component, it is possible to obtain butadiene rubber (B-BR) derived from biological resources (biomass resources), and by using styrene obtained from biological resources and butadiene obtained from biological resources as monomer components, it is possible to obtain styrene-butadiene rubber (B-SBR) derived from biological resources (biomass resources). Here, methods for obtaining B-BR and B-SBR from biological resources include, in addition to artificial polymerization methods, methods of polymerization in vivo, and methods of polymerization with 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 according to the target tire performance.

[0134] As the butadiene obtained from the biological resources, butadiene derived from alkyl alcohols (preferably ethanol and butanol, more preferably butanol), butadiene derived from alkenes (preferably ethylene), and butadiene derived from unsaturated carboxylic acids (preferably tiglic acid) can be suitably used. Two or more of these butadienes may be used in combination. As the styrene obtained from the biological resources, styrene obtained from a plant (preferably a plant belonging to the family Hamamelidaceae, Styraxaceae, or Apocynaceae, more preferably a plant belonging to the genera Liquidambar, Styrax, or Catharanthus, and even more preferably Sweetgum, Styrax rosa, or Catharanthus roseus) or a microorganism (preferably a microorganism belonging to the genera Penicillium or Escherichia, more preferably P. citrinum or transformed E. coli) can be suitably used. Two or more of these styrenes may be used in combination.

[0135] Recently, biomass combinat mainly using bioethanol, bioethylene, etc. are planned, but bioethanol and bioethylene are mainly produced using sugars and / or cellulose as biological resources, and other biological resources such as proteins, lipids, and amino acids cannot be effectively utilized. Furthermore, sugars compete with food, and excessive use of cellulose leads to deforestation. Therefore, it is preferable to use multiple types of monomer components derived from biological resources as the monomer components derived from the biological resources, or to use monomer components derived from biological resources, monomer components derived from renewable resources, and monomer components derived from fossil resources in combination, and further to appropriately adjust the ratio of these monomer components. This makes it possible to effectively utilize a wide range of biological resources and renewable resources such as sugars, proteins, and lipids without relying on one type of biological resource, and to stably supply rubber derived from sustainable materials, and further to consider the environment depending on the situation at the time of production. In addition, when using multiple types of monomer components derived from biological resources, 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 butadiene derived from multiple types of biological resources with different origins as the butadiene derived from biological resources, and / or to use a mixture of styrene derived from multiple types of biological resources with different origins as the styrene derived from biological resources. This allows multiple types of biological resources to be effectively utilized.

[0136] (resin) The rubber composition of the present invention further contains a resin, The resin includes at least one selected from the group consisting of a terpene-based resin and a terpene-aromatic compound-based resin, and a rosin-based resin. By including a rosin-based resin as an essential component in addition to at least one selected from the group consisting of a terpene-based resin and a terpene-aromatic compound-based resin, low rolling resistance and low temperature properties can be further improved. In addition, the increased compatibility with the rubber component improves the dispersibility of carbon black and silica, which will be described later, and provides a better balance of low rolling resistance, low temperature properties, and handling stability. Furthermore, the use of raw materials derived from fossil fuels in the rubber composition can be reduced, lessening the burden on the environment, and the ratio of raw materials derived from natural resources (the ratio of sustainable materials) in the rubber composition can be improved.

[0137] The terpene resin is a solid resin obtained by blending turpentine oil, which is obtained at the same time as rosin is obtained from pine trees, or a polymerization component separated from the turpentine oil, and polymerizing the blend using a Friedel-Crafts catalyst. Examples of the terpene resin include β-pinene resin and α-pinene resin.

[0138] Representative examples of the terpene-aromatic compound resin include terpene-phenol resin and styrene-terpene resin. The terpene-phenol resin can be obtained by reacting terpenes with various phenols using a Friedel-Crafts catalyst, or by further condensing with formalin. The styrene-terpene resin can be obtained by reacting styrene with terpenes using a Friedel-Crafts catalyst. The terpenes used as the raw material are not particularly limited, and are preferably monoterpene hydrocarbons such as α-pinene and limonene, more preferably those containing α-pinene, and particularly preferably α-pinene.

[0139] 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. Examples of modified rosin, rosin derivatives, and modified rosin derivatives include polymerized rosin, partially hydrogenated rosin thereof, glycerin ester rosin, partially hydrogenated rosin thereof, and fully hydrogenated rosin thereof, pentaerythritol ester rosin, partially hydrogenated rosin thereof, and polymerized rosin, etc.

[0140] In addition to the above-mentioned terpene resin, terpene-aromatic compound resin, and rosin resin, the resin may include C5 resin, C5-C9 resin, C9 resin, cyclopentadiene resin, aromatic resin, coumarone resin, indene resin, coumarone-indene resin, olefin resin, polyurethane resin, acrylic resin, etc. These resins may be used alone or in combination of two or more. Among these resins, C5 resin, C5-C9 resin, C9 resin, cyclopentadiene resin, and aromatic resin are preferred. C5 resin, C9 resin, C5-C9 resin, and cyclopentadiene resin can improve wear resistance and fuel economy in a well-balanced manner. In addition, aromatic resin can improve grip performance, wear resistance, and rubber strength in a well-balanced manner.

[0141] Furthermore, the resin may be hydrogenated, i.e., may be a hydrogenated resin (hydrogenated resin). In addition, the resin may be modified to introduce a functional group that interacts with a filler such as carbon black or silica. Examples of the functional group include an amino group, an amide group, an isocyanate group, an imino group, an imidazole group, a urea group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, an ether group, a carbonyl group, an oxycarbonyl group, a silyl group, an alkoxysilyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, and a thiocarbonyl group.

[0142] The C5 resins include aliphatic petroleum resins obtained by (co)polymerizing C5 fractions obtained by thermal cracking of naphtha in the petrochemical industry. C5 fractions usually include 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.

[0143] The C5-C9 resin refers to a C5-C9 synthetic petroleum resin. Examples of the C5-C9 resin include petroleum-derived C5-C 11 Examples of the solid polymers include those obtained by polymerizing the fraction using a Friedel-Crafts catalyst such as AlCl3 or BF3, and more specifically, copolymers mainly composed of styrene, vinyltoluene, α-methylstyrene, indene, etc. As the C5-C9 resin, a resin with a small amount of C9 or more components is preferred from the viewpoint of compatibility with the rubber component. Here, "a small amount of C9 or more components" means that the amount of C9 or more components in the total amount of the resin is less than 50 mass%, preferably 40 mass% or less.

[0144] The C9 resin refers to a C9 synthetic petroleum resin, for example, a solid polymer obtained by polymerizing a C9 fraction using a Friedel-Crafts catalyst such as AlCl3 or BF3. Examples of the C9 resin include copolymers mainly composed of indene, α-methylstyrene, vinyltoluene, etc.

[0145] The cyclopentadiene resin refers to a resin containing a unit derived from a cyclopentadiene monomer as a monomer unit. Examples of the cyclopentadiene resin include a homopolymer of a cyclopentadiene monomer, a copolymer of two or more cyclopentadiene monomers, and a copolymer of a cyclopentadiene monomer and another monomer. Here, examples of the cyclopentadiene monomer include cyclopentadiene, dicyclopentadiene, and tricyclopentadiene, and among these, dicyclopentadiene is preferred, that is, the cyclopentadiene resin is preferably a dicyclopentadiene resin. The dicyclopentadiene resin refers to a resin obtained by polymerizing dicyclopentadiene using a Friedel-Crafts catalyst such as AlCl3 or BF3. Examples of dicyclopentadiene resins include homopolymers of dicyclopentadiene, copolymers of dicyclopentadiene and aromatic monomers, and copolymers of dicyclopentadiene and C9 fractions (vinyl toluene, indene, etc.).

[0146] The aromatic resin refers to a resin containing a unit derived from an aromatic monomer as a monomer unit. Examples of the aromatic resin include a homopolymer of an aromatic monomer, a copolymer of two or more aromatic monomers, and a copolymer of an aromatic monomer and another monomer. Examples of the aromatic monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, and p-phenylstyrene; phenolic monomers such as phenol, alkylphenol, and alkoxyphenol; and naphthol monomers such as naphthol, alkylnaphthol, and alkoxynaphthol.

[0147] The softening point of the resin is preferably 30° C. or higher, more preferably 60° C. or higher, more preferably 80° C. or higher, more preferably higher than 110° C., more 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 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. In this specification, the softening point of the resin is the temperature at which the ball drops when the softening point defined in JIS K 6220-1:2015 (ISO 28641:2010) is measured using a ring and ball softening point tester.

[0148] As the resin, commercially available products can be used, and examples of commercially available resin products that can be used include products from ENEOS Corporation, Arakawa Chemical Industries, Ltd., ExxonMobil Corporation, Clayton, Yasuhara Chemical Co., Ltd., Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Clayton Polymers, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., and Taoka Chemical Co., Ltd.

[0149] The resin has an SP value difference of 0.6 (cal / cm) from that of the isoprene skeleton rubber. 3 ) 1 / 2 It is preferable that: The difference in SP value between the resin and the isoprene skeleton rubber is 0.6 (cal / cm 3 ) 1 / 2 By being equal to or less than this, compatibility with isoprene skeleton rubber is increased, the mobility of the rubber component is controlled, and the hysteresis loss (tan δ) in the low temperature region can be improved, thereby improving the low temperature properties and workability of a tire to which the rubber composition is applied. Note that, from the viewpoint of further improving compatibility, the difference in SP value between the resin and the isoprene skeleton rubber is set to 0.59 (cal / cm 3 ) 1 / 2It is preferable that the calorie content is 0.58 (cal / cm 3 ) 1 / 2 More preferably, it is 0.57 (cal / cm 3 ) 1 / 2 It is more preferable that the difference in SP value between the resin component and the isoprene skeleton rubber is 0.6 (cal / cm 3 ) 1 / 2 When the content is equal to or less than this, the compatibility between the resin component and the isoprene skeleton rubber is further improved, and the wet grip performance of a tire to which the rubber composition is applied is further improved. On the other hand, it is also preferable that the resin has a polystyrene-equivalent weight average molecular weight of 500 g / mol or more and 1300 g / mol or less. When the polystyrene-equivalent weight average molecular weight of the resin is 500 g / mol or more, the resin component is less likely to precipitate from the tire and the effects of the resin component can be fully exhibited, and when it is 1300 g / mol or less, the resin component is easily compatible with the rubber component. Therefore, from the viewpoint of suppressing precipitation of the resin component from the tire and suppressing deterioration of the tire appearance, the polystyrene-equivalent weight average molecular weight of the resin is preferably 500 g / mol or more, more preferably 550 g / mol or more, more preferably 600 g / mol or more, more preferably 650 g / mol or more, and even more preferably 700 g / mol or more. Also, from the viewpoint of increasing the compatibility of the resin component with the rubber component and further enhancing the effect of the resin component, the polystyrene-equivalent weight average molecular weight of the resin component is more preferably 1250 g / mol or less, more preferably 1230 g / mol or less, more preferably 1220 g / mol or less, and even more preferably 1200 g / mol or less.

[0150] In addition, the mass ratio of the resin to the isoprene skeleton rubber [mass ratio of resin component / isoprene skeleton rubber] is preferably 0.5 or more. By setting the mass ratio of the resin to the isoprene skeleton rubber within the above range, the wet grip performance of a tire to which the rubber composition is applied can be further improved. The mass ratio of the resin to the isoprene skeleton rubber [mass ratio of resin component / isoprene skeleton rubber] is preferably 0.10 or more, more preferably 0.20 or more, more preferably 0.25 or more, and is preferably 2.0 or less, more preferably 1.9 or less, and even more preferably 1.8 or less.

[0151] The total content of at least one selected from the group consisting of terpene-based resins and terpene-aromatic compound-based resins, and rosin-based resin in the rubber composition of the present invention is 1 to 50 parts by mass per 100 parts by mass of the rubber component. When the content of at least one selected from the group consisting of terpene resins and terpene-aromatic compound resins, and rosin resin in the rubber composition is 1 part by mass or more per 100 parts by mass of the rubber component, the effect of the resin is fully expressed, and when it is 50 parts by mass or less, the resin component is less likely to precipitate from the tire, and the effect of the resin component can be fully expressed. On the other hand, when the content of the resin component exceeds 50 parts by mass per 100 parts by mass of the rubber component, the fuel efficiency performance and wear resistance performance of the tire to which the rubber composition is applied deteriorate. From the viewpoint of further enhancing the effect of the resin component, the content of the resin component 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. In addition, from the viewpoint of suppressing precipitation of the resin component from the tire and suppressing deterioration in the tire appearance, the content of the resin component 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.

[0152] (Reinforcing filler) Moreover, the rubber composition of the present invention preferably further contains a reinforcing filler. This is because the vulcanized rubber composition of the present invention can have improved properties such as breaking strength, abrasion resistance, low rolling resistance, grip performance, etc. The reinforcing filler may be any reinforcing filler commonly used in the rubber field, such as carbon black, silica, talc, clay, aluminum hydroxide, titanium oxide, etc.

[0153] ·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 has a large number of silanol groups. These silicas may be used alone or in combination of two or more. Commercially available products of the silica can be used, and examples of the commercially available silica products include products from Tosoh Silica Co., Ltd., Evonik, Solvay, Solvay Japan Co., Ltd., Tokuyama Corporation, and the like. From the viewpoint of reducing the environmental load, it is also preferable to use, as the silica, silica obtained by extracting silicic acid components from scraps of silicon wafers, which are the raw material for semiconductors, glass bottles, etc., and recycling the extracted silica for use in the production.

[0154] As the silica, silica derived from silicic acid plants is preferred from the viewpoint of reducing environmental load. The silicic acid plants are present, for example, in mosses, ferns, horsetails, Cucurbitaceae, Urticaceae, and Gramineae plants. Among these plants, Gramineae plants are preferred. In addition, the Gramineae plants include rice, bamboo grass, sugarcane, and the like, among which rice is preferred. Since rice is widely cultivated for food, it can be procured locally in a wide area, and since rice husks are generated in large quantities as industrial waste, it is easy to secure the amount. Therefore, from the viewpoint of easy availability, silica derived from rice husks (hereinafter also referred to as "rice husk silica") is particularly preferred as silica. By using the rice husk silica, rice husks that become industrial waste can be effectively utilized, and since the raw material can be procured locally near the tire manufacturing plant, the energy and cost of transportation and storage can be reduced, which is environmentally preferable from various viewpoints. The rice husk silica may be a powder of rice husk charcoal obtained by carbonizing rice husks by heating, or may be precipitated silica produced by a wet method 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 and extracting the rice husk ash with an alkali silicate aqueous solution. The method for producing the rice husk charcoal is not particularly limited, and various known methods can be used. For example, rice husks can be pyrolyzed by steaming them in a kiln to obtain rice husk charcoal. The rice husk charcoal thus obtained is pulverized using a known pulverizer (for example, 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.

[0155] The silica has a nitrogen adsorption specific surface area (N2SA) of 50 m 2 / g or more, and 2 / g or more is more preferable, and 150m 2 / g or more is more preferable, and 350m 2 / g or less, and 2 / g or less is more preferable, 2 / g or less is more preferable, 2It is even more preferable that the molecular weight is not more than 1 / g. In this specification, the nitrogen adsorption specific surface area (N2SA) of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0156] The silica has a nitrogen adsorption specific surface area (BET method) of 80 m 2 / g or more 330m 2 It is more preferable that the nitrogen adsorption specific surface area (BET method) of silica is less than 80 m 2 When the nitrogen adsorption specific surface area (BET method) of silica is 330 m / g or more, a tire to which the rubber composition is applied can be sufficiently reinforced, and the rolling resistance of the tire can be further reduced. 2 When the silica has a nitrogen adsorption specific surface area (BET method) of 110 m / g or less, the elastic modulus of the rubber composition is not too high, and the wet grip performance of a tire using the rubber composition is further improved. 2 / g or more, and 2 / g or more, and 150m 2 / g or more, and 2 From the viewpoint of further improving the wet grip performance of the tire, the nitrogen adsorption specific surface area (BET method) of the silica is preferably 300 m 2 / g or less, and 2 / g or less is more preferable, and 2 It is more preferable that the molecular weight is not more than 1 / g.

[0157] The content of the silica can be appropriately adjusted depending on, for example, the tire category to which the rubber composition is applied, the tire components, the target performance, etc. For example, the content of the silica is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 50 parts by mass or more, still more preferably 60 parts by mass or more, particularly preferably 110 parts by mass or more, and is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 180 parts by mass or less, and particularly preferably 150 parts by mass or less, relative to 100 parts by mass of the rubber component.

[0158] Carbon black The filler preferably contains carbon black, which reinforces the rubber composition and improves the abrasion resistance of the rubber composition. The carbon black is not particularly limited, and examples thereof include GPF, FEF, HAF, ISAF, and SAF grade carbon black. These carbon blacks may be used alone or in combination of two or more.

[0159] From the viewpoint of improving the wear resistance of the rubber composition and a tire using the same, the content of 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 the rubber component. Also, 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 the rubber component. When the filler contains silica and carbon black, the proportion of silica in the total amount of silica and carbon black is preferably 80% by mass or more and less than 100% by mass, and more preferably 90% by mass or more and less than 100% by mass. When the proportion of silica is 80% by mass or more, the mechanical strength of a tire to which the rubber composition is applied is improved, and the rolling resistance can be further reduced.

[0160] The carbon black is particularly preferably plant-derived carbon black or carbon black obtained by recycling. Examples of plant-derived carbon black include those derived from castor oil and rosin oil. Examples of carbon black obtained by recycling include carbon black obtained by pyrolysis of used tires and carbon black obtained from waste oil. The grade of the carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. As the carbon black, commercially available products can be used, and examples of commercially available carbon black products include products from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Birla Carbon Co., Ltd., and the like. These carbon blacks may be used alone or in combination of two or more.

[0161] (Silane coupling agent) In addition, when the rubber composition of the present invention contains silica, in order to improve the effect of the silica, the rubber composition of the present invention preferably contains a silane coupling agent.The silane coupling agent includes 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, Examples of the silane coupling agent 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, dimethoxymethylsilylpropyl benzothiazolyl tetrasulfide, etc. As the silane coupling agent, a commercially available product can be used, and examples of the commercially available silane coupling agent include products from Evonik, Momentive, Shin-Etsu Silicone 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.

[0162] The content of the silane coupling agent can be appropriately adjusted depending on, for example, the tire category to which it is applied, the tire components, the target performance, etc. For example, the content of the silane coupling agent is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, even more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the silica.

[0163] Bioethanol can also be used as a raw material for the silane coupling agent. Bioethanol is produced mainly using sugars and / or cellulose as biological resources, and other biological resources such as proteins, lipids, and amino acids cannot be effectively utilized. Furthermore, sugars compete with food, and excessive use of cellulose leads to deforestation. Therefore, it is preferable to use multiple types of monomer components derived from biological resources as the monomer components derived from the biological resources, or to use a monomer component derived from a biological resource, a monomer component derived from a renewable resource, and a monomer component derived from a fossil resource in combination, depending on the supply status of various biological resources, the supply status of renewable resources, the supply status of fossil resources, and market demands (for example, the demand for biomass resources as food). This makes it possible to effectively utilize a wide range of biological resources and renewable resources such as sugars, proteins, and lipids without relying on one type of biological resource, and also to consider the environment depending on the situation during production.

[0164] (rubber powder) The rubber composition of the present invention preferably contains rubber powder. The rubber powder may be obtained by crushing used rubber products such as used tires, removing reinforcing materials such as steel materials and fibers, dust, glass, sand, stones, etc., as desired, or preparing a new vulcanized rubber composition to produce rubber powder and crushing it. For example, rubber powder can be obtained from vulcanized rubber by the method described in "Rubber Chemistry And Technology". In the process of crushing vulcanized rubber to obtain rubber powder, mechanical treatment or low-temperature treatment may be used. For example, in the mechanical treatment, various crushing devices such as a cracker mill and a granulator can be used to mechanically crush the vulcanized rubber into fine particles. In the low-temperature treatment, the finely chopped vulcanized rubber is frozen at a very low temperature and then crushed into fine particles. In addition, a magnetic separator or the like can be used to remove steel materials, and an air separator or the like can be used to remove fibers. As the rubber powder, commercially available products can be used, and examples of commercially available rubber powder include products from Global Corporation or Nantong Huili Rubber Corporation. From the viewpoint of reducing the environmental load, 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 kinds.

[0165] The composition of the rubber powder is not particularly limited, and depends on the composition of vulcanized rubber such as used rubber products (used tires) that serve as a raw material. In one embodiment, the rubber powder contains a rubber component, carbon black, silica, etc. The rubber component, carbon black, silica, etc. contained in the rubber powder may be the same as or different from the rubber component, carbon black, silica, etc. contained in the rubber composition of the present embodiment described above.

[0166] The rubber powder has a volume average particle size of preferably 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 size of the rubber powder, the better, and there is no particular lower limit. In this specification, the volume average particle size is measured by a laser diffraction particle size distribution measuring device, for example, "CAPA500" manufactured by Horiba, Ltd.

[0167] The rubber powder has a 60 mesh sieve residue of preferably less than 1 mass%, more preferably 0.5 mass% or less, and even more preferably 0.1 mass% or less, with no particular lower limit. Also, the rubber powder has an 80 mesh sieve residue of preferably less than 10 mass%, more preferably 1 mass% or less, and even more preferably 0.5 mass% or less, with no particular lower limit. In this specification, the sieve residue is measured in accordance with ASTM D5644-01.

[0168] The rubber powder 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 extractables in the rubber crumb means the acetone extractables (%) determined by the acetone extraction method in accordance with JIS K6350.

[0169] The content of rubber powder in the rubber component is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the rubber component is applied, tire components, target performance, etc. For example, the content of rubber powder 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, even 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.

[0170] (liquid softener) Furthermore, the rubber composition of the present invention 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 preferable. These liquid softeners may be used alone or in combination of two or more.

[0171] The oil is a general term for the extender oil contained in the rubber component and the liquid oil added as a compounding agent of the rubber composition, and examples thereof include vegetable oil, process oil, oil obtained by recycling vegetable oil or process oil, or a mixture thereof. From the viewpoint of reducing the environmental load, the oil is preferably vegetable oil or oil obtained by recycling. Examples of the vegetable oil include palm oil, castor oil, cottonseed oil, soybean oil, linseed oil, rapeseed oil, coconut oil, peanut 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, coconut oil, etc. Examples of the process oil include paraffin-based process oil, aromatic process oil, naphthene-based process oil, etc. The oil may be a commercially available product, and examples of the commercially available oil include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi 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.

[0172] The liquid polymer is preferably a liquid diene polymer. Examples of the liquid diene 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 the 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.

[0173] The content of the liquid softener is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which it is applied, the tire components, the target performance, etc. For example, the content of the liquid softener is preferably 5 parts by mass or more, and 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, even 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.

[0174] (Anti-aging agent) Furthermore, the rubber composition of the present invention may contain an antioxidant, such as N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine, 2,2,4-trimethyl-1,2-dihydroquinoline polymer (TMDQ), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (AW), and 6-anilino-2,2,4-trimethyl-1,2-dihydroquinoline. As the antiaging agent, commercially available products can be used, and examples of the commercially available antiaging agent include products from Ouchi Shinko Chemical Industry Co., Ltd., Sumitomo Chemical Co., Ltd., Seiko Chemical Co., Ltd., Flexis, Inc., Tsurumi Chemical Industry Co., Ltd., etc. These antiaging agents may be used alone or in combination of two or more.

[0175] The content of the antiaging agent is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the tire is applied, the tire components, the target performance, etc. For example, the content of the antiaging agent is preferably 1 part by mass or more per 100 parts by mass of the rubber component. The content of the antiaging agent is preferably 12 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less per 100 parts by mass of the rubber component.

[0176] (wax) The rubber composition of the present invention may contain a wax. Examples of the wax include natural waxes such as vegetable wax and animal wax; 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 the commercially available waxes include products from Seiko Chemical Co., Ltd., Nippon Seiro Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and the like. These waxes may be used alone or in combination of two or more.

[0177] The content of the wax is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the rubber is applied, the tire components, the target performance, etc. 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, based on 100 parts by mass of the rubber component.

[0178] (Stearic acid) The rubber composition of the present invention may contain stearic acid. Commercially available stearic acid may be used, and examples of the commercially available stearic acid include products from NOF Corp., Kao Corp., Fujifilm Wako Pure Chemical Corp., Chiba Fatty Acid Corp., etc. These commercially available stearic acid products may be used alone or in combination of two or more.

[0179] The content of stearic acid is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the rubber composition is applied, the tire components, the target performance, etc. For example, the content of stearic acid is preferably 1 part by mass or more per 100 parts by mass of the rubber component. Also, the content of stearic acid 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.

[0180] (Zinc Oxide) The rubber composition of the present invention may also 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 the 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., Toho Zinc Co., Ltd., and the like. These commercially available zinc oxide products may be used alone or in combination of two or more.

[0181] The content of the zinc oxide is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the rubber composition is applied, the tire components, the target performance, etc. For example, the content of the zinc oxide 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.

[0182] (sulfur) Furthermore, the rubber composition of the present invention preferably contains sulfur. The sulfur may be derived from fossil resources, recycled resources, or materials derived from biological resources. From the viewpoint of reducing the environmental load, it is particularly preferable to use sulfur obtained from waste derived from biological resources. Examples of a method for obtaining sulfur from waste derived from biological resources include the method described in the above-mentioned Japanese Patent Application No. 2022-140390. In addition, the sulfur may be powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are generally used as crosslinking agents in the rubber industry. As the sulfur, commercially available products can be used, and examples of commercially available sulfur products include products from Tsurumi Chemical Industry Co., Ltd., Hosoi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Co., Ltd., Nippon Kanzuri Kogyo Co., Ltd., etc. These sulfurs may be used alone or in combination of two or more types.

[0183] The sulfur content is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the rubber is applied, tire components, target performance, etc. For example, the sulfur content is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.8 parts by mass or more, and is preferably 8 parts by mass or less, and more preferably 5 parts by mass or less, relative to 100 parts by mass of the rubber component.

[0184] (Cellulose nanofiber) The rubber composition of the present invention may contain cellulose nanofibers (CNF). The cellulose nanofibers can reinforce the rubber composition by blending them with the rubber composition. The cellulose nanofibers are preferably modified cellulose nanofibers, which are fine fibers made from modified cellulose. The fiber diameter of the cellulose nanofibers is not particularly limited, but is about 3 to 500 nm. The average fiber diameter and average fiber length of the cellulose nanofibers can be obtained by averaging the fiber diameters and fiber lengths obtained from the results of observing each fiber using a scanning electron microscope (SEM), an atomic force microscope (AFM), or a transmission electron microscope (TEM). The cellulose nanofibers can be obtained by defibrating cellulose. The average fiber length and average fiber diameter of the fine fibers can be adjusted by oxidation treatment and defibration treatment.

[0185] 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.

[0186] The content of the cellulose nanofibers is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the rubber is applied, the tire components, the target performance, etc. 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 weight, and even more preferably in the range of 10 to 40 parts by mass, relative to 100 parts by mass of the rubber component.

[0187] (Porous cellulose particles) The rubber composition of the present invention 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 compounding them with the rubber composition, the performance on ice can be improved. When the porosity of the porous cellulose particles is 75% or more, the effect of improving the 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 a sample (i.e., the porous cellulose particles) with a measuring cylinder, calculating the bulk density, and using the following formula. Porosity (%) = {1-[bulk specific gravity of sample (g / mL)] / [true specific gravity of sample (g / mL)]} x 100 Here, the true specific gravity of cellulose is 1.5.

[0188] The particle size of the porous cellulose particles is not particularly limited, but from the viewpoint of abrasion resistance, the average particle size is preferably 1000 μm or less. The lower limit of the average particle size is not particularly limited, but is preferably 5 μm or more. The average particle size is more preferably 100 to 800 μm, and further preferably 200 to 800 μm. The porous cellulose particles are preferably spherical particles having a major axis / minor axis ratio of 1 to 2. By using particles having such a spherical structure, the dispersibility in the rubber composition is improved, which contributes to improving performance on ice and maintaining abrasion resistance, etc. The major axis / minor axis ratio is more preferably 1.0 to 1.5. The average particle size and the long axis / short axis ratio of the porous cellulose particles are obtained as follows: That is, the porous cellulose particles are observed under a microscope to obtain an image, and the long axis and short axis of the particles (when the long axis and short axis are the same, the length in a certain axis direction and the length in an axis direction perpendicular to the long axis) are measured for 100 particles using the image, and the average particle size is obtained by calculating the average value, and the long axis / short axis ratio is obtained by averaging the values ​​obtained by dividing the long axis by the short axis.

[0189] The porous cellulose particles are commercially available from Rengo Co., Ltd. under the name "Viscopearl" and are described in JP-A-2001-323095, JP-A-2004-115284, etc., and these can be suitably used.

[0190] The content of the porous cellulose particles is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the rubber is applied, the tire components, the target performance, 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 weight, and further preferably in the range of 3 to 15 parts by mass, relative to 100 parts by mass of the rubber component.

[0191] (solid fine particles) The rubber composition of the present invention may contain solid fine particles. The solid fine particles can improve the performance on ice by blending them with the rubber composition. The solid fine particles preferably have an average particle diameter of 1 μm or more, and more preferably 1000 μm or less, and more preferably 300 μm or less. Examples of the solid fine particles include powders derived from plants, such as rice husks, walnut powder, and walnut shells; powders derived from animals, such as eggshells (eggshell powder) and bone powder; powders derived from natural minerals, such as whitebait; inorganic fine particles, such as graphite and zinc oxide whiskers; water-soluble metal salt fine particles, such as magnesium sulfate and metal salts of lignin sulfonate; non-metallic fibers, such as glass fibers; and the like. Among these, rice husks, walnut shells, eggshells, and whitebait are preferred.

[0192] The content of the solid fine particles is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the rubber composition is applied, tire components, target performance, 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 weight, and further preferably in the range of 3 to 15 parts by mass, relative to 100 parts by mass of the rubber component.

[0193] (Other Ingredients) In addition to the above-mentioned components, the rubber composition of the present invention may contain compounding agents that are commonly used in the rubber industry as other components. As for the other components, for example, fillers other than the above-mentioned reinforcing fillers; organic peroxides; etc. may be further compounded. The content of these additives is not particularly limited and can be appropriately adjusted depending on, for example, the tire category to which it is applied, tire components, target performance, etc., and is preferably in the range of 0.1 to 200 parts by mass with respect to 100 parts by mass of the rubber component.

[0194] (Method of manufacturing rubber composition) The method for producing the rubber composition of the present invention is not particularly limited, but for example, the rubber composition of the present invention can be produced by blending various components appropriately selected as necessary with the rubber component, and kneading, heating, extruding, etc. In addition, the obtained rubber composition can be vulcanized to produce a vulcanized rubber.

[0195] 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 the 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.

[0196] The conditions of the heat-in are not particularly limited, and various conditions such as the heat-in temperature, heat-in time, heat-in equipment, etc. can be appropriately selected depending on the purpose. Examples of the heat-in equipment include a heat-in roller machine usually used for heat-in of a rubber composition.

[0197] 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 that is usually used for extruding a rubber composition. The extrusion temperature can be appropriately determined.

[0198] The vulcanization apparatus, method, conditions, etc. are not particularly limited and can be appropriately selected according to the purpose. As the vulcanization apparatus, a molding vulcanizer using a mold used for vulcanizing a rubber composition can be mentioned. As the vulcanization condition, the temperature is, for example, about 100 to 190°C.

[0199] <Tires> The tire of the present invention is characterized by including the rubber composition of the present invention described above. By using the rubber composition of the present invention, a tire having excellent low rolling resistance, low temperature characteristics, and steering stability, as well as improved workability and a ratio of sustainable materials can be obtained. The tire of the present invention can be used, for example, as a tire for construction vehicles, a tire for trucks and buses, a tire for aircraft, and a tire for passenger cars.

[0200] In addition, when using the above-mentioned rubber composition of the present invention, for example, an unvulcanized rubber composition may be used for molding and then vulcanized, or a semi-vulcanized rubber that has been subjected to a pre-vulcanization process or the like may be used for molding and then further vulcanized. The tire of this embodiment is preferably a pneumatic tire, and the gas to be filled in 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.

[0201] In the tire of the present invention, the above-mentioned rubber composition of the present invention can be used, for example, in the tread (base tread, cap tread, under tread), cushion rubber, shoulder, sidewall, clinch, bead filler, carcass coating rubber, insulation, chafer, inner liner, etc., and can also be used in the side reinforcing layer of a run-flat tire, etc. In addition to tires, the rubber composition of the present invention can also be applied to rubber crawlers, seismic isolation rubber, hoses, etc. EXAMPLES

[0202] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0203] [Reference Examples 1-2, Comparative Example 1] Rubber composition samples were prepared by compounding and kneading in a conventional manner according to the formulation shown in Table 1. In Table 1, the compounding amount of each component is expressed as an integer. Others are expressed to one decimal place.

[0204] <Evaluation>

[0205] (1) Low rolling resistance For the vulcanized rubber test pieces obtained from each rubber composition sample, tan δ was measured using a viscoelasticity measuring device (manufactured by Ueshima Seisakusho Co., Ltd.) at a temperature of 50° C., a strain of 0.1%, and a frequency of 52 Hz. The tan δ measured in each example was indexed with the tan δ of Comparative Example 1 set at 100. The smaller the index value, the lower the heat build-up of the vulcanized rubber, and the lower the rolling resistance of the tire obtained from the vulcanized rubber (the better the low rolling resistance). The evaluation results are shown in Table 1.

[0206] (2) Handling stability The storage modulus (E') of the test specimen was measured using a viscoelasticity measuring device (manufactured by Ueshima Seisakusho Co., Ltd.) under conditions of a temperature of 30°C, a strain of 0.1%, and a frequency of 52 Hz. The evaluation results were expressed as an index, with the E' of Comparative Example 1 being set at 100. A larger index value indicates a larger E' and better dry handling performance.

[0207] (3) Low-temperature characteristics The loss modulus (E') of the test piece was measured using a viscoelasticity measuring device (Ueshima Seisakusho Co., Ltd.) under conditions of a temperature of -20°C, a strain of 0.1%, and a frequency of 52 Hz. The evaluation results were expressed as an index, with the E' of Comparative Example 1 set at 100. The smaller the index value, the smaller the E' and the more excellent the low-temperature properties.

[0208] (4) Proportion of sustainable materials For each rubber composition sample, the total mass ratio of materials derived from biological resources (biomass resources) and materials derived from recycled resources (recycled resources) was calculated to calculate the sustainable material ratio. The higher the score, the higher the rate of sustainable material usage and the better the product. The evaluation results are shown in Table 1.

[0209] [Table 1]

[0210] *1 TSR#20, SP value = 8.20 (cal / cm 3 ) 1 / 2 *2 Hydrocarbyloxysilane compound modified styrene-butadiene rubber synthesized by the following method, Tg = -65°C, SP value = 8.65 (cal / cm 3 ) 1 / 2 *3 Styrene-butadiene rubber obtained by using butyl lithium as an initiator, with a Tg of -38°C and modified ends with N-(1,3-dimethylbutylidene)-3-triethoxysilyl-1-propaneamine, Tg=-38°C, SP value=8.95 (cal / cm 3 ) 1 / 2 *4 Asahi Carbon Co., Ltd., product name "#80" *5 Tosoh Silica Corporation, product name "Nipsil AQ" *6 Showa Denko K.K., product name "Hijilite H-43M", average particle size = 1.0μm *7 Evonik, product name "Si75" *8 Zeon Corporation, product name "Quinton (registered trademark) G100B" *9 Kraton Corporation, product name "SYLVATRAXX8125", SP value = (estimated) 8.76 (cal / cm 3 ) 1 / 2 , weight average molecular weight (Mw)=1218g / mol *10 Kraton Corporation, product name "SYLVATRAXX2097", SP value = (estimated) 9.97 (cal / cm 3 ) 1 / 2 , weight average molecular weight (Mw)=1157g / mol *11 Sigma-Aldrich, product number "307564" *12 The total amount of antioxidant, vulcanization accelerator, and sulfur is the same in both the Reference Comparative Example and Reference Example.

[0211] From the results in Table 1, it can be seen that the rubber compositions of Reference Examples 1 and 2 show improved results in terms of the ratio of sustainable materials compared to the rubber composition of Reference Comparative Example. It can also be seen that the rubber composition of Reference Example 1 has improved low rolling resistance and low temperature properties compared to the rubber composition of Reference Comparative Example 1, and the rubber composition of Reference Example 2 has improved handling stability compared to the rubber composition of Reference Comparative Example 1. Therefore, a formulation containing at least one resin selected from the group consisting of terpene-based resins and terpene-aromatic compound-based resins used in the rubber composition of Reference Example 1 and the rosin-based resin used in the rubber composition of Reference Example 2 is expected to achieve a balance between low rolling resistance, low temperature characteristics, handling stability, and the ratio of sustainable materials. [Industrial Applicability]

[0212] According to the present invention, it is possible to provide a rubber composition which has low rolling resistance, excellent low-temperature properties and handling stability, and also has an improved ratio of sustainable materials. Moreover, according to the present invention, it is possible to provide a tire which has low rolling resistance, excellent low-temperature characteristics and handling stability, and which also has an improved ratio of sustainable materials.

Claims

1. A rubber composition comprising a rubber component and a resin, the resins include at least one selected from the group consisting of a terpene-based resin and a terpene-aromatic compound-based resin, and a rosin-based resin in a total amount of 1 to 50 parts by mass per 100 parts by mass of the rubber component; The rubber component contains an isoprene skeleton rubber and a styrene-butadiene rubber, The rubber composition is characterized in that the styrene-butadiene rubber has a glass transition temperature of less than -40°C.

2. The resin has an SP value difference of 0.6 (cal / cm) from the isoprene skeleton rubber. ３ ) １／２ The rubber composition according to claim 1, characterized in that the rubber composition has a polystyrene-equivalent weight average molecular weight of 500 to 1300 g / mol or less.

3. 3. The rubber composition according to claim 1, wherein the content of the isoprene skeleton rubber is 1 to 80 parts by mass in 100 parts by mass of the rubber component.

4. The rubber composition according to claim 3, wherein the content of the isoprene skeleton rubber is 1 to 40 parts by mass per 100 parts by mass of the rubber component.

5. 3. The rubber composition according to claim 1, wherein the styrene-butadiene rubber is modified with a modifier having a functional group containing a nitrogen atom and an alkoxy group.

6. A tire comprising the rubber composition according to claim 1 or 2.

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