Modified silica, rubber composition and tire

Abstract

To provide modified silica that exhibits reversible changes in physical properties due to water, and rubber compositions and tires containing the modified silica.SOLUTION: The present invention relates to modified silica modified with boronic acid compounds.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In order to improve fuel efficiency in tires, the incorporation of silica as a filler to achieve good low heat buildup has been investigated. However, silica has silanol groups on its surface and is hydrophilic, so it has low affinity with rubber, which is generally hydrophobic. Furthermore, it has a strong tendency to self-aggregate, making it difficult to disperse uniformly in rubber.

[0003] As a method for improving the dispersibility of silica in a rubber composition, for example, a method has been proposed in which a predetermined amount of an organic group-containing urea compound is compounded in a diene-based rubber composition containing silica (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-89693 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, although investigations have been carried out from the viewpoint of silica dispersibility, there is still room for improvement in terms of imparting various other properties to silica.

[0006] The present invention aims to solve the above problems and to provide a modified silica that exhibits reversible changes in physical properties when exposed to water, as well as a rubber composition and a tire that contain the modified silica. [Means for solving the problem]

[0007] The present invention relates to a modified silica modified with a boronic acid compound. [Effects of the Invention]

[0008] According to the present invention, since the silica is modified with a boronic acid compound, by compounding it with a rubber composition, the rubber composition can be endowed with the function of undergoing reversible changes in physical properties in response to water. [Brief explanation of the drawings]

[0009] [Figure 1] This is an example of a synthesis example in which boronic acid compound-modified silica is synthesized. [Figure 2] This is an example of the 13C-NMR spectrum of the intermediate and synthetic products. [Figure 3] 1 shows an example of the TGA measurement results of amine-modified silica and boronic acid compound-modified silica. [Figure 4] This is an example of a synthesis example in which a phenylboronic acid compound represented by formula (2) is synthesized. [Figure 5] This is an example of the 1H-NMR spectrum of the synthesized product. [Figure 6] 1 is an example of synthesis showing a route by which a phenylboronic acid compound reacts with a polymer to synthesize a modified polymer. [Figure 7] This is an example of an IR spectrum and 1H-NMR spectrum of a synthetic substance. [Figure 8] This is an example of a synthesis example in which boronic acid compound-modified silica is synthesized. [Figure 9] 1 shows an example of the TGA measurement results of amine-modified silica and boronic acid compound-modified silica. [Figure 10] 1 shows an example of TGA measurement results for a liquid butadiene polymer and an amine-modified liquid butadiene polymer. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Modified Silica> The modified silica modified with the above-mentioned boronic acid compound can exhibit reversible changes in physical properties when exposed to water.

[0011] The reason why the above-mentioned effects are obtained is not entirely clear, but it is presumed that the following mechanism is involved. When modified silica obtained by reacting silica with a boronic acid compound (modified silica in which silica and a boronic acid compound are chemically bonded) is dried, it undergoes reversible dehydration condensation of three molecules to form boroxine (boroxine crosslinks). Then, upon contact with water, the formed boroxine crosslinks decompose. Thus, upon drying, silica with boroxine crosslinks is formed, while upon swelling with water, the boroxine crosslinks decompose to form the modified silica. Therefore, the modified silica can exhibit reversible changes in physical properties due to water. Furthermore, for example, when a rubber composition containing the modified silica is used in a tire, the elastic modulus decreases upon contact with water, increasing loss on wet roads and improving wet grip performance.

[0012] The modified silica is silica modified with a boronic acid compound. The boronic acid compound is not particularly limited as long as it is a compound having a group in which two hydroxyl groups are bonded to a boron atom. From the viewpoint of obtaining a better effect, however, it is preferably a boronic acid compound represented by the following formula (1): R 1 -B(OH)2(1) In the above formula (1), R 1 represents a substituted or unsubstituted monovalent hydrocarbon group.

[0013] In the above formula (1), R 1 Examples of the substituted or unsubstituted monovalent hydrocarbon group represented by the formula (I) include an alkyl group (preferably having 1 to 30 carbon atoms, more preferably having 1 to 20 carbon atoms, and even more preferably having 1 to 10 carbon atoms), an alkenyl group (preferably having 2 to 30 carbon atoms, more preferably having 2 to 20 carbon atoms, and even more preferably having 2 to 10 carbon atoms), an alkynyl group (preferably having 2 to 30 carbon atoms, more preferably having 2 to 20 carbon atoms, and even more preferably having 2 to 10 carbon atoms), an aryl group (preferably having 6 to 30 carbon atoms, more preferably having 6 to 20 carbon atoms, and even more preferably having 6 to 10 carbon atoms), and an aralkyl group (preferably having 7 to 30 carbon atoms, more preferably having 7 to 20 carbon atoms, and even more preferably having 7 to 10 carbon atoms). Furthermore, when the hydrocarbon group is substituted, examples of the substituent include a hydroxyl group, a carboxyl group, an aldehyde group, a ketone group, and a substituted or unsubstituted amino group (when the amino group is substituted, the substituent is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms).

[0014] Of the above boronic acid compounds, the phenylboronic acid compound represented by the following formula (2) is more preferred from the viewpoint of obtaining a greater effect. [ka] (R 11 are the same or different, and are monovalent hydrocarbon groups which may have a substituent and may contain a heteroatom. n is an integer of 1 to 5.

[0015] In the above formula (2), R 11 Examples of the monovalent hydrocarbon group constituting the skeleton of R include linear, cyclic, or branched alkyl groups, alkenyl groups, aryl groups, and aralkyl groups, with alkyl groups being particularly preferred. 11 The number of carbon atoms is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and is preferably 30 or less, more preferably 20 or less, even more preferably 10 or less, and particularly preferably 6 or less. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, and a decyl group.

[0016] In the above formula (2), R 11 The substituents in 11The substituent may be added to the skeleton of the monovalent hydrocarbon group constituting the skeleton or may be introduced into the skeleton. The substituent is not particularly limited, and examples thereof include known groups. Examples include alkoxy groups having 1 to 4 carbon atoms, such as methoxy, ethoxy, and butoxy; halogen atoms, such as chlorine, bromine, iodine, and fluorine; aryl groups having 6 to 12 carbon atoms, such as phenyl, naphthyl, and biphenyl; and polar groups, such as oxo (=O), hydroxy, carboxyl, carbonyl, aldehyde, amino, acetyl, amide, imide, and thiol. From the viewpoint of reactivity with the polymer, the substituent is preferably a carboxyl, aldehyde, amino, or thiol group.

[0017] From the viewpoint of obtaining a function of reversibly changing physical properties by water, the above-mentioned substituent is preferably a group having an oxygen atom, more preferably a carboxyl group or an aldehyde group, and even more preferably an aldehyde group.

[0018] In the modified silica, the silica modified with the boronic acid compound is not particularly limited, and any silica can be used.

[0019] The silica that can be used is not particularly limited, and can be, for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrated silica), or other silica commonly used in the tire industry. The raw material for silica is not particularly limited, and can be, for example, a mineral-derived raw material such as quartz, a biological raw material such as rice husk (for example, silica made from biomass materials such as rice husk), or silica recycled from silica-containing products. Among these, hydrated silica prepared by a wet method is preferred because it contains a large number of silanol groups. These silicas can be used alone or in combination of two or more types.

[0020] Silica made from biomass materials can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then reacting the silicate with sulfuric acid in the same manner as conventional wet-process silica to produce a silicon dioxide precipitate, which is then filtered, washed with water, dried, and pulverized.

[0021] Silica recycled from silica-containing products can be, for example, silica recovered from products containing silica, such as electronic components such as semiconductors, tires, desiccants, and filtering materials such as diatomaceous earth. The recovery method is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from electronic components such as semiconductors or tires is preferred.

[0022] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and duration, it is possible to suppress the crystallization of silica in rice husk ash (see, for example, JP 2009-2594 A and Akita Prefectural University Web Journal B / 2019, vol. 6, pp. 216-222).

[0023] Amorphous silica extracted from rice husks may be commercially available from Wilmar Co., Ltd., etc.

[0024] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 10 m 2 / g or more, more preferably 20m 2 / g or more, more preferably 30m 2 The upper limit of the N2SA of silica is not particularly limited, but is preferably 300 m 2 / g or less, more preferably 275m 2 / g or less, more preferably 250m 2 Within the above range, better tire performance such as wet grip performance tends to be obtained. In this specification, the N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0025] From the viewpoint of reactivity with the boronic acid compound, the silica is preferably silica having a functional group. Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl 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, and an epoxy group. These functional groups may have a substituent. Among them, from the viewpoint of reactivity with the boronic acid compound, an amino group, an epoxy group, a carboxyl group, and the like are preferred, and an amino group is more preferred.

[0026] The reaction process between the boronic acid compound and the silica is not particularly limited, and known methods can be used. The reaction may be carried out in a solvent such as an organic solvent in water, or without a solvent. The solvent is not particularly limited, but is preferably one in which both the boronic acid compound and the silica are easily dispersed. The reaction temperature and time may be appropriately set depending on the boronic acid compound and the silica, so that the reaction proceeds. The mixing ratio of the boronic acid compound and the silica used in the reaction may be appropriately selected within a range in which the reaction can proceed.

[0027] The solvent is not particularly limited and may be appropriately selected from those that allow the reaction to proceed, including, for example, ethers such as ethylene glycol dimethyl ether, tetrahydrofuran, and 1,4-dioxane, aromatic hydrocarbons such as toluene, alcohols such as ethanol and methanol, water, and mixtures thereof.

[0028] To explain a specific example of compound synthesis, for example, modified silica (boronic acid compound-modified silica) can be synthesized by the synthesis route shown in FIG.

[0029] Specifically, as shown in Figure 1, for example, a boronic acid compound having an aldehyde group and silica having an amino group (amine-modified silica) are reacted overnight at room temperature in a solvent (methanol), followed by reduction with sodium borohydride (NaBH4) to synthesize modified silica modified with the boronic acid compound (boronic acid compound-modified silica). After completion of the reaction, the filtrate is recovered by suction filtration or the like and dried to obtain the target reaction product (boronic acid compound-modified silica). In FIG. 1, Si represents silica.

[0030] Furthermore, modified silica 1 (boronic acid compound-modified silica 1) and modified silica 2 (boronic acid compound-modified silica 2) can be synthesized by the synthetic route shown in Figure 8. That is, not only modified silica 2 (boronic acid compound-modified silica 2), which is the target reactant of the synthetic route shown in Figure 1, but also modified silica 1 (boronic acid compound-modified silica 1), which is the intermediate, can be used as the above-mentioned modified silica (boronic acid compound-modified silica).

[0031] Specifically, as shown in Figure 8, for example, a boronic acid compound having an aldehyde group and silica having an amino group (amine-modified silica) are reacted overnight at room temperature in a solvent (methanol) to synthesize modified silica 1 (boronic acid compound-modified silica 1). After completion of the reaction, the filtrate is recovered by suction filtration or the like and dried to obtain the target reaction product (boronic acid compound-modified silica 1). Furthermore, modified silica 1 (boronic acid compound-modified silica 1) is dispersed in a solvent (methanol) and reduced with sodium borohydride (NaBH4) to synthesize modified silica 2 (boronic acid compound-modified silica 2). After the reaction is complete, the filtrate is recovered by suction filtration or the like and dried to obtain the target reaction product (boronic acid compound-modified silica 2). In FIG. 8, Si represents silica.

[0032] The modified silica preferably has a Schiff base structure, such as the modified silica 1 (boronic acid compound-modified silica 1). The Schiff base structure may be, for example, an imine structure represented by =C=N- (C and N are the same or different and are bonded to a hydrogen atom and a hydrocarbon group). Examples of the hydrocarbon group include the monovalent hydrocarbon groups described above and the divalent hydrocarbon groups described below.

[0033] The reason why modified silica having a Schiff base structure is desirable is not entirely clear, but is presumed to be due to the following mechanism. R 11 R 21 C=NR 31 The Schiff base having the structure shown in Figure 1 is thought to be water-responsive. Therefore, for example, the modified silica 1 (boronic acid compound-modified silica 1) having a Schiff base can form boroxine (boroxine crosslink) in the absence of water, while both boroxine decomposition and Schiff base decomposition occur in the presence of water. Therefore, modified silica having a Schiff base structure, such as the above-mentioned modified silica 1 (boronic acid compound-modified silica 1), is considered to have a higher water responsiveness than modified silica not having a Schiff base structure, such as the above-mentioned modified silica 2 (boronic acid compound-modified silica 2), and therefore it is presumed that it is more desirable to use modified silica having a Schiff base structure.

[0034] <Rubber composition> The rubber composition includes a modified silica modified with a boronic acid compound and a rubber component. When the rubber composition is used, the modified silica modified with the boronic acid compound imparts a function of reversible change in physical properties in response to water. For example, when the rubber composition is used in a tire component, the modulus of elasticity decreases upon contact with water, increasing loss on wet road surfaces, thereby improving wet grip performance.

[0035] The rubber composition includes a rubber component. In this specification, the rubber component is a component that contributes to crosslinking, and generally refers to a polymer component that is a polymer with a weight-average molecular weight (Mw) of 10,000 or more and is not extracted with acetone. The rubber component is in a solid state at 25°C.

[0036] The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, even more preferably 200,000 or more, and particularly preferably 270,000 or more, and is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less. Within the above ranges, the effect tends to be more favorable.

[0037] In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) can be determined in terms of standard polystyrene based on measurements obtained 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).

[0038] The rubber component may be either an unmodified rubber or a modified rubber. Examples of modified rubbers include rubbers having functional groups that interact with fillers such as silica. Examples include terminal-modified rubbers (terminal-modified rubbers having the functional groups at the terminals) in which at least one terminal of the rubber has been modified with a compound (modifier) having the functional group, main-chain-modified rubbers having the functional groups in the main chain, main-chain-terminal-modified rubbers having the functional groups in the main chain and at the terminals (for example, main-chain-terminal-modified rubbers having the functional groups in the main chain and at least one terminal modified with the modifier), and terminal-modified rubbers modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having hydroxyl groups or epoxy groups introduced therein.

[0039] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imido 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, and an epoxy group. These functional groups may have a substituent. Among these, an amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms) are preferred.

[0040] Examples of the rubber component include diene rubber. Examples of diene rubber include isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). Examples of the rubber component also include butyl rubber and fluororubber. These rubber components may be modified or hydrogenated, and extended rubber extended with oil, resin, liquid rubber component, or the like may be used. These may be used alone or in combination of two or more. Among these, it is preferable to contain at least one of isoprene rubber, BR, and SBR, more preferably to contain at least one of BR and SBR, and even more preferably to contain at least BR and SBR.

[0041] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. NRs such as SIR20, RSS#3, and TSR20 are commonly used in the rubber industry. IRs are not particularly limited, and examples of IRs such as IR2200 are commonly used in the rubber industry. Modified NRs include deproteinized natural rubber (DPNR) and high-purity natural rubber. Modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

[0042] The BR is not particularly limited, and examples thereof include high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, and BR synthesized using a rare earth catalyst (rare earth BR). These may be used alone or in combination of two or more. Of these, the BR preferably contains high-cis BR with a cis content of 90% by mass or more. The cis content is more preferably 95% by mass or more. The cis content can be measured by infrared absorption spectroscopy.

[0043] The cis content of BR means the cis content of the BR when there is one type of BR, and means the average cis content when there are multiple types of BR. The average cis content of BR can be calculated by {Σ(content of each BR × cis content of each BR)} / total content of all BRs. For example, when 100% by mass of the rubber component contains 20% by mass of BR with a cis content of 90% by mass and 10% by mass of BR with a cis content of 40% by mass, the average cis content of BR is 73.3% by mass (=(20×90+10×40) / (20+10)).

[0044] Both unmodified and modified BR can be used. Modified BR includes modified BR with the same functional groups as modified rubber. Hydrogenated butadiene polymer (hydrogenated BR) can also be used.

[0045] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0046] The SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. These may be used alone or in combination of two or more.

[0047] The styrene content of the SBR is preferably 5% by mass or more, more preferably 20% by mass or more, even more preferably 24% by mass or more, and even more preferably 27.5% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less. Within the above range, the effect tends to be more favorable. In this specification, the styrene content is 1 It can be measured by H-NMR measurement.

[0048] The styrene content of SBR means the styrene content of the SBR when there is one type of SBR, and means the average styrene content when there are multiple types of SBR. The average styrene amount of SBR can be calculated by {Σ(content of each SBR × styrene amount of each SBR)} / total content of all SBRs. For example, when 100% by mass of the rubber component contains 85% by mass of SBR with a styrene amount of 40% by mass and 5% by mass of SBR with a styrene amount of 25% by mass, the average styrene amount of the SBR is 39.2% by mass (=(85×40+5×25) / (85+5)).

[0049] The vinyl bond content of the SBR is preferably 3% by mass or more, more preferably 10% by mass or more, and even more preferably 17% by mass or more. The vinyl bond content is preferably 70% by mass or less, more preferably 65% by mass or less, even more preferably 60% by mass or less, and even more preferably 59% by mass or less. When the vinyl bond content is within the above range, better effects tend to be obtained. In this specification, the vinyl bond amount (amount of 1,2-bonded butadiene units) can be measured by infrared absorption spectroscopy.

[0050] The vinyl content of SBR (amount of 1,2-bonded butadiene units) is the proportion of vinyl bonds (unit: mass%) when the total mass of the butadiene parts in the SBR is taken as 100, and is calculated as vinyl content [mass%] + cis content [mass%] + trans content [mass%] = 100 [mass%]. When there is one type of SBR, it means the vinyl content of that SBR, and when there are multiple types, it means the average vinyl content. The average vinyl content of SBR can be calculated by Σ{content of each SBR × (100 [mass%] - styrene content of each SBR [mass%]) × vinyl content of each SBR [mass%]} / Σ{content of each SBR × (100 [mass%] - styrene content of each SBR [mass%])}. For example, in 100 parts by mass of the rubber component, 75 parts by mass of SBR with a styrene content of 40% by mass and a vinyl content of 30% by mass, 25 parts by mass of styrene and 10 parts by mass of vinyl are used. In the case where 15 parts by mass of SBR with a vinyl content of 20% by mass is used and the remaining 10 parts by mass are other than SBR, the average vinyl content of the SBR is 28% by mass (= {75 × (100 [% by mass] - 40 [% by mass]) × 30 [% by mass] + 15 × (100 [% by mass] - 25 [% by mass]) × 20 [% by mass])} / {75 × (100 [% by mass] - 40 [% by mass]) + 15 × (100 [% by mass] - 25 [% by mass])}.

[0051] Both unmodified and modified SBR can be used. Modified SBR includes modified SBR with the same functional groups as modified rubber. Hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can also be used as SBR.

[0052] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used. SBR synthesized by a known method can also be used.

[0053] The raw materials (monomers) for synthetic rubbers such as IR, SBR, and BR may be derived from underground resources such as petroleum and natural gas, or may be recycled from rubber products such as tires or non-rubber products such as polystyrene. Monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl include, but are not limited to, styrene. Among these, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0054] The method for producing the recycled monomer is not particularly limited, and examples thereof include synthesis from recycled naphtha obtained by decomposing rubber products such as tires. The method for producing recycled naphtha is also not particularly limited, and examples thereof include decomposing rubber products such as tires under high temperature and pressure, decomposing with microwaves, or mechanically crushing and then extracting.

[0055] Furthermore, the raw materials (monomers) of synthetic rubbers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to materials derived from natural resources such as plants. Examples of biomass include, but are not limited to, agricultural, forestry, and fishery products, sugar, wood chips, plant residues after useful components have been extracted, plant-derived ethanol, and biomass naphtha.

[0056] Monomers derived from biomass (biomass monomers) are not particularly limited and include biomass-derived butadiene and biomass-derived aromatic vinyl. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyls include, but are not limited to, styrene. The method for producing biomass monomers is not particularly limited and includes, for example, biological and / or chemical and / or physical conversion of animals and plants. A typical example of biological conversion is fermentation by microorganisms, and examples of chemical and / or physical conversion include catalytic conversion, high heat conversion, high pressure conversion, electromagnetic wave conversion, critical fluid conversion, and combinations thereof.

[0057] Polymers synthesized from biomass monomer components (biomass polymers) are not particularly limited and include polybutadiene rubber synthesized from biomass-derived butadiene, aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl, etc. Examples of the aromatic vinyl / butadiene copolymers include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0058] Whether the raw material for a polymer is derived from biomass can be determined by the pMC (percent modern carbon) measured in accordance with ASTM D6866-10.

[0059] pMC is the modern standard reference 14 of sample against C concentration 14 This is the ratio of C concentrations and is a value used as an index of the biomass ratio of a compound. The significance of this value is explained below.

[0060] 1 mole of carbon atoms (6.02 × 10 23 ) contains approximately 6.02 × 10 atoms, which is about one trillionth of the number of ordinary carbon atoms. 11 pieces 14C exists. 14 C is called a radioactive isotope, and its half-life is 5,730 years, and it decreases regularly. It takes 226,000 years for all of it to decay. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been absorbed and fixed by plants and other organisms more than 226,000 years ago, C was also included in these when it was first fixed. 14 All C elements have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas contain 14 Therefore, chemicals produced from these fossil fuels do not contain any C element. 14 It does not contain any C element.

[0061] on the other hand, 14 C is produced continuously by nuclear reactions in the atmosphere caused by cosmic rays, and this balances with the decrease due to radioactive decay. In the Earth's atmospheric environment, 14 Therefore, the amount of carbon derived from biomass resources currently circulating in the environment is constant. 14 As mentioned above, the C concentration is approximately 1 × 10 -12 The value is approximately mol %. Therefore, the biomass ratio of a certain compound can be calculated by using the difference between these values.

[0062] this 14 C is typically measured using accelerator mass spectrometry based on a tandem accelerator. 13 C concentration ( 13 C / 12 C). 14 C concentration ( 14 C / 12 C) is measured. 14 The modern standard reference for the C concentration is the carbon circulating in nature as of 1950. 14The specific standard substance used is the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific activity of carbon in this oxalic acid (per gram of carbon) is 14 The radioactivity of C) is separated into carbon isotopes, 13 The standard value is the value corrected for decay from 1950 to the measurement date. 14 This is used as the C concentration value (100%). The ratio of this value to the value of the actually measured sample is the pMC value.

[0063] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, under normal circumstances, it will usually not reach 100, and will show a value of approximately 110 pMC. On the other hand, for chemical substances derived from petroleum and other fossil fuels, 14 When the carbon concentration is measured, it will show a value of about 0 pMC (for example, 0.3 pMC), which corresponds to the biomass ratio of 0% mentioned above.

[0064] From the above, it is preferable in terms of environmental protection to use a material such as rubber having a high pMC value, that is, a material such as rubber having a high biomass ratio, in a rubber composition.

[0065] When the rubber composition contains an isoprene-based rubber as a rubber component, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Alternatively, the content may be 100% by mass, but is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. Within the above ranges, better effects tend to be obtained.

[0066] When the rubber composition contains BR, the content of BR in 100% by mass of the rubber component is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. When the content is within the above range, better effects tend to be obtained.

[0067] When the rubber composition contains SBR, the content of SBR in 100% by mass of the rubber component is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. When the content is within the above range, better effects tend to be obtained.

[0068] The rubber component preferably contains a modified rubber modified with a boronic acid compound. From the viewpoint of obtaining a greater effect, the boronic acid compound is preferably a boronic acid compound represented by the above formula (1). The preferred form of formula (1) is as described above.

[0069] The reason why the above-mentioned effects are obtained is not entirely clear, but it is presumed that the following mechanism is involved. When modified rubber obtained by reacting rubber with a boronic acid compound is dried, it undergoes reversible dehydration condensation with three molecules to form boroxine (boroxine crosslinks). Then, upon contact with water, the formed boroxine crosslinks decompose. Thus, upon drying, rubber with boroxine crosslinks is formed, while upon swelling with water, the boroxine crosslinks decompose to form the modified rubber. Therefore, the modified rubber, together with the modified silica, can exhibit reversible changes in physical properties in response to water. For example, when a rubber composition containing the modified rubber is used in a tire, the modulus of elasticity decreases upon contact with water, further increasing loss on wet roads and further improving wet grip performance.

[0070] From the viewpoint of obtaining even greater effects, the boronic acid compound is more preferably a phenylboronic acid compound represented by the following formula (2). [ka] (R 11 are the same or different, and are monovalent hydrocarbon groups which may have a substituent and may contain a heteroatom. n is an integer of 1 to 5.

[0071] In equation (2), R 11 Examples of the monovalent hydrocarbon group constituting the skeleton of R include linear, cyclic, or branched alkyl groups, alkenyl groups, aryl groups, and aralkyl groups, with alkyl groups being particularly preferred. 11 The number of carbon atoms is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and is preferably 30 or less, more preferably 20 or less, even more preferably 10 or less, and particularly preferably 6 or less. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, and a decyl group.

[0072] In the above formula (2), R 11 The substituents in 11 The substituent may be added to the skeleton of the monovalent hydrocarbon group that constitutes the skeleton, or may be introduced into the skeleton. The substituent is not particularly limited, and examples thereof include known groups. Examples include alkoxy groups having 1 to 4 carbon atoms, such as methoxy, ethoxy, and butoxy; halogen atoms, such as chlorine, bromine, iodine, and fluorine; aryl groups having 6 to 12 carbon atoms, such as phenyl, naphthyl, and biphenyl; and polar groups, such as oxo (=O), hydroxy, carboxyl, carbonyl, amino, acetyl, amide, imide, and thiol. From the viewpoint of reactivity with the polymer, the substituent is preferably a carboxyl, amino, or thiol group.

[0073] The substituent is preferably a group having a nitrogen atom, more preferably an amino group, from the viewpoint of obtaining a function of reversibly changing physical properties in response to water.

[0074] The reason why the above-mentioned effects are obtained is not entirely clear, but it is presumed that the following mechanism is involved. As described above, when modified rubber reacted with a phenylboronic acid compound represented by formula (2) is dried, it undergoes reversible dehydration condensation of three molecules to form boroxine (boroxine crosslink). Then, upon contact with water, the resulting boroxine crosslink decomposes, presumably providing a water-induced reversible property change function. Furthermore, when ordinary phenylboroxine undergoes hydrolysis, heating is required for dehydration recondensation of three molecules. However, in the case of phenylboronic acid compounds containing nitrogen atoms, particularly phenylboronic acid compounds in which the nitrogen atom is located near the phenylboroxine group, dehydration recondensation of three molecules is possible even at room temperature. Therefore, it is presumed that the use of modified rubber reacted with a phenylboronic acid compound represented by formula (2) can more effectively provide a water-induced reversible property change function.

[0075] In the above formula (2), R 11 When the phenylboronic acid compound of formula (2) has a nitrogen atom, the nitrogen atom is preferably bonded to the boron atom of the phenylboronic acid compound of formula (2) via 1 to 6 carbon atoms, from the viewpoint of obtaining a function of reversibly changing physical properties in response to water. The number of carbon atoms is preferably 2 to 5, more preferably 2 to 4, and even more preferably 2 to 3.

[0076] R 11 The amino group of the substituent in the above formula (I) includes, for example, a primary amino group (-NH2), a secondary amino group (-NHR 1 ), tertiary amino group (-NR 1 R 2 ) are listed. 1 and R 2 is exemplified by an alkyl group, a phenyl group, an aralkyl group, etc., and the R 1 , R 2The number of carbon atoms in the amino group is preferably 1 to 8. The amino group may be an ammonium salt group, such as a tertiary ammonium salt group or a quaternary ammonium salt group. The amino group may also be a divalent amino group. Examples of the divalent amino group include -N(H)-, -N(R 3 )-. 3 is exemplified by an alkyl group, a phenyl group, an aralkyl group, etc., and the R 3 The number of carbon atoms in R is preferably 1 to 8. In the case of a divalent amino group, for example, R 11 is introduced into the skeleton of

[0077] R 11 Examples of the heteroatom in include a nitrogen atom, an oxygen atom, a sulfur atom, etc. Among these, a nitrogen atom is preferred from the viewpoint of obtaining a greater effect.

[0078] In formula (2), n is preferably 1 to 4, more preferably 1 to 3, even more preferably 1 or 2, and particularly preferably 1, from the viewpoint of obtaining a better effect.

[0079] From the viewpoint of obtaining a greater effect, among the phenylboronic acid compounds represented by the above formula (2), the compound represented by the following formula (2-1) is preferred. [ka] (R 21 and R 22 R are the same or different, and are divalent hydrocarbon groups which may have a substituent and may contain a heteroatom. 23 ~R 25 are the same or different and are hydrogen atoms or monovalent hydrocarbon groups which may have a substituent and may contain a heteroatom; and m is an integer of 1 to 5.

[0080] The reason why the above-mentioned effects are obtained is not entirely clear, but it is presumed that the following mechanism is involved. As mentioned above, when ordinary phenylboroxines are hydrolyzed, heating is required for the dehydration recondensation of three molecules, but in the case of the phenylboronic acid compound represented by formula (2-1), dehydration recondensation of three molecules is possible even at room temperature. Therefore, it is presumed that the use of modified rubber reacted with the compound represented by formula (2-1) can better impart the function of reversible changes in physical properties due to water.

[0081] In formula (2-1), R 21 and R 22 The divalent hydrocarbon group constituting the skeleton of R may be linear, cyclic, or branched, and examples thereof include alkylene groups, alkenylene groups, cycloalkylene groups, cycloalkylalkylene groups, arylene groups, and aralkylene groups. 21 and R 22 The number of carbon atoms is preferably 1 to 30, more preferably 1 to 15, still more preferably 1 to 8, and particularly preferably 1 to 5. Specific examples include a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, and a hexamethylene group.

[0082] R 21 and R 22 The substituents in 21 and R 22 The substituent may be added to the skeleton of the divalent hydrocarbon group constituting the skeleton of the above group or may be introduced into the skeleton. 11 The substituents are the same as those of R 21 and R 22 Regarding the heteroatom in the above, for example, 11 The heteroatoms are the same as those in the above.

[0083] R 23 ~R 25 Examples of the monovalent hydrocarbon group constituting the skeleton of R 11 The monovalent hydrocarbon groups constituting the skeleton of R 23 ~R 25 The substituents in 23 ~R 25The substituent may be added to the skeleton of the monovalent hydrocarbon group constituting the skeleton of the above group or may be introduced into the skeleton. 11 The substituents are the same as those of R 23 ~R 25 Regarding the heteroatom in the above, for example, 11 The heteroatoms are the same as those in the above.

[0084] Among them, R 23 From the viewpoint of obtaining a greater effect, is preferably a hydrogen atom or a monovalent hydrocarbon group, and more preferably a hydrogen atom. R 24 From the viewpoint of obtaining a greater effect, is preferably a hydrogen atom or a monovalent hydrocarbon group, and more preferably a hydrogen atom. R 25 From the viewpoint of obtaining a greater effect, is preferably a hydrogen atom or a monovalent hydrocarbon group, and more preferably a hydrogen atom.

[0085] In formula (2-1), m is preferably 1 to 4, more preferably 1 to 3, still more preferably 1 or 2, and particularly preferably 1, from the viewpoint of obtaining a better effect.

[0086] The phenylboronic acid compound represented by the formula (2) can be synthesized by a known method. Hereinafter, an example of a method for synthesizing the phenylboronic acid compound will be described, but the phenylboronic acid compound is not limited to those obtained by such a synthesis method, and includes compounds obtained by any synthesis method that can be synthesized.

[0087] For example, a specific phenylboronic acid compound and the above R 11 A phenylboronic acid compound represented by formula (2) can be synthesized by reacting the compound with a compound capable of introducing a group represented by formula (2).

[0088] The above reaction is usually carried out in a solvent. The solvent used in the reaction is not particularly limited, and any solvent that allows the reaction to proceed may be selected as appropriate. Examples include ethers such as ethylene glycol dimethyl ether, tetrahydrofuran, and 1,4-dioxane, aromatic hydrocarbons such as toluene, water, and mixtures thereof. A known catalyst may be used in the reaction, such as a palladium catalyst. The amount of the catalyst used in the reaction may be selected as appropriate. The phenylboronic acid compound used in the reaction and the above-mentioned R 11 The mixing ratio of the compound capable of introducing a group represented by the formula (I) may be appropriately selected within a range in which the reaction proceeds smoothly. The reaction temperature is usually in the range of 50 to 110°C, and the reaction time is usually in the range of 1 to 24 hours. After completion of the reaction, the target product can be isolated by carrying out post-treatment operations such as extracting the reaction mixture with an organic solvent and concentrating the organic layer, and if necessary, further purifying it by recrystallization, chromatography, etc.

[0089] To explain a specific example of compound synthesis, for example, phenylboronic acid compound C can be synthesized according to the synthetic route shown in FIG.

[0090] As shown in FIG. 4, for example, phenylboronic acid compound B is reacted with an amine compound in a solvent (methanol) at room temperature overnight, reduced with sodium borohydride (NaBH), and deprotected with hydrochloric acid (HCl) to synthesize phenylboronic acid compound C.

[0091] The rubber constituting the skeleton of the modified rubber may be the same as the rubber component described above. From the viewpoint of reactivity with the phenylboronic acid compound represented by the formula (2), the rubber is preferably a rubber having a functional group. Examples of the functional group include the above-mentioned functional groups, and among them, epoxy groups, amino groups, and carboxyl groups are preferred.

[0092] The reaction process between a boronic acid compound (particularly, a phenylboronic acid compound represented by the above formula (2)) and the rubber is not particularly limited, and known methods can be used. The reaction may be carried out in a solvent such as an organic solvent in water, or without a solvent. The solvent is not particularly limited, but is preferably one in which both the boronic acid compound and the rubber are easily soluble. Specific examples of solvents include those mentioned above. The reaction temperature and time may be appropriately set depending on the boronic acid compound and the rubber.

[0093] When the rubber component contains a modified rubber modified with a boronic acid compound, the content of the modified rubber modified with the boronic acid compound in 100% by mass of the rubber component is not particularly limited, but is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. The upper limit is not particularly limited, but is preferably 70% by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less. Within the above range, the effects tend to be favorably obtained.

[0094] The rubber composition contains modified silica modified with a boronic acid compound. The modified silica is as described above.

[0095] The amount of the modified silica is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, even more preferably 30 parts by mass or more, and even more preferably 60 parts by mass or more, per 100 parts by mass of the rubber component. Furthermore, the amount is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 85 parts by mass or less, even more preferably 80 parts by mass or less, and even more preferably 75 parts by mass or less, per 100 parts by mass of the rubber component. Within the above ranges, the effect tends to be better.

[0096] The rubber composition may contain fillers other than the modified silica. The other filler is not particularly limited, and materials known in the rubber field can be used, including, for example, inorganic fillers such as carbon black, silica other than the above-mentioned modified silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, mica, biochar, poorly dispersible fillers, etc. Among these, carbon black and silica other than the above-mentioned modified silica are preferred from the viewpoint of obtaining greater effects.

[0097] In the rubber composition, the content of the filler (total amount of fillers such as carbon black, the modified silica, and silica other than the modified silica) is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, still more preferably 31 parts by mass or more, and even more preferably 66 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, even more preferably 100 parts by mass or less, still more preferably 90 parts by mass or less, and even more preferably 81 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0098] Usable carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. The raw material for carbon black may be a biomass material such as lignin or vegetable oil, or pyrolysis oil obtained by pyrolysis of waste tires. Carbon black may be produced by combustion, such as in a furnace, by hydrothermal carbonization (HTC), or by thermal decomposition of methane, such as in a thermal black process. Commercially available carbon blacks include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These may be used alone or in combination.

[0099] The nitrogen adsorption specific surface area (N2SA) of carbon black is 5m 2 / g or more is preferable, and 30m 2 / g or more is more preferable, and 50m 2 / g or more is more preferable. 2 / g or less is preferable, and 114m 2 / g or less is more preferable, and 100m 2 / g or less is more preferable, and 90m 2 Within the above range, the effect tends to be better. The nitrogen adsorption specific surface area of carbon black can be determined according to JIS K6217-2:2001.

[0100] In the rubber composition, the content of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and still more preferably 6 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0101] Usable silica other than the above-mentioned modified silica is not particularly limited, and is the same as the silica modified with a boronic acid compound in the above-mentioned modified silica.

[0102] In the rubber composition, the content of silica other than the modified silica 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, and is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0103] Examples of the hardly dispersible filler include microfibrillated plant fibers, short fiber cellulose, gel compounds, etc. Among these, microfibrillated plant fibers are preferred.

[0104] The microfibrillated plant fiber is preferably cellulose microfibrils, as they provide good reinforcing properties. The cellulose microfibrils are not particularly limited as long as they are derived from natural products, and examples include those derived from resource biomass such as fruits, grains, and root vegetables; wood, bamboo, hemp, jute, and kenaf; pulp, paper, and cloth obtained from these raw materials; waste biomass such as agricultural waste, food waste, and sewage sludge; unused biomass such as rice straw, wheat straw, and thinned wood; and cellulose produced by sea squirts, acetic acid bacteria, and the like. These microfibrillated plant fibers may be used alone or in combination of two or more.

[0105] In this specification, cellulose microfibrils typically refer to cellulose fibers having an average fiber diameter of 10 μm or less, more typically cellulose fibers having a microstructure formed by the aggregation of cellulose molecules and an average fiber diameter of 500 nm or less. Typical cellulose microfibrils are formed, for example, as an aggregate of cellulose fibers having the above-mentioned average fiber diameter.

[0106] When the rubber composition contains a hardly-dispersible filler, the content of the hardly-dispersible filler 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. The upper limit of the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0107] The rubber composition preferably further contains a silane coupling agent. The silane coupling agent is not particularly limited, and those known in the rubber field can be used, for example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N, Examples include sulfide-based compounds such as N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z manufactured by Momentive; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products that can be used include those from Evonik, Momentive, Shin-Etsu Silicones Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Dow Corning Toray Co., Ltd. These may be used alone or in combination of two or more.

[0108] In the rubber composition, the content of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, relative to 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0109] The rubber composition may contain a plasticizer. In this specification, the term "plasticizer" refers to a material that imparts plasticity to a rubber component, and includes both plasticizers that are liquid at 25°C and plasticizers that are solid at 25°C. Examples of plasticizers include resin components, oils, liquid polymers, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, biomass-derived plasticizers, or naphtha recycled from rubber and non-rubber products. Low-molecular-weight hydrocarbon components obtained by pyrolysis and extraction of used tires or products containing various components may also be used as plasticizers. These plasticizers may be used alone or in combination.

[0110] Specific examples of the plasticizer include oil, liquid polymer, resin, etc. These may be used alone or in combination of two or more.

[0111] Examples of oils include mineral oil, vegetable oil, animal oil, etc. From the viewpoint of life cycle assessment, waste oils used in rubber mixers or engines, or refined waste cooking oils used in restaurants may also be used.

[0112] As used herein, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oil (mineral oil), naphthenic oil, and aromatic oil. Specific examples of mineral oil include mild extract solvated (MES), distillate aromatic extract (DAE), treated distillate aromatic extract (TDAE), treated residual aromatic extract (TRAE), and residual aromatic extract (RAE). Furthermore, as an environmental measure, oils with a low content of polycyclic aromatic compounds (PCA) can also be used. Examples of low PCA oils include MES, TDAE, and heavy naphthenic oil.

[0113] As used herein, examples of vegetable oils include linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and Japan wax. Further examples of vegetable oils include refined oils (such as salad oil) obtained by refining the above-mentioned oils, interesterified oils obtained by interesterifying the above-mentioned oils, hardened oils obtained by hydrogenating the above-mentioned oils, thermally polymerized oils obtained by thermally polymerizing the above-mentioned oils, oxidatively polymerized oils obtained by oxidizing the above-mentioned oils, and waste edible oils recovered from edible oils and the like. Vegetable oils may be liquid or solid at 25°C. These vegetable oils may be used alone or in combination of two or more.

[0114] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin is esterified with a fatty acid. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer (trimer or higher). Dimer or higher acylglycerols can be obtained by thermal polymerization, oxidative polymerization, or the like. The acylglycerol may be liquid or solid at 25°C.

[0115] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, but may be 1 For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours, and after removing the rubber composition, the 1 When H-NMR was measured, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm when the signal of tetramethylsilane (TMS) was set at 0.00 ppm. These signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atoms of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0116] The fatty acid is not particularly limited and may be either an unsaturated fatty acid or a saturated fatty acid. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0117] Among these, it is desirable that the fatty acid contains a fatty acid with few double bonds, i.e., a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As a vegetable oil containing such a fatty acid, for example, vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or vegetable oil modified by ester exchange or the like may be used. Furthermore, in order to produce vegetable oil containing such a fatty acid, plants may be improved by breeding, genetic modification, genome editing, or the like.

[0118] As the oil, for example, commercially available oils from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi Co., Ltd., H&R Corporation, Toyokuni Oil Mills Co., Ltd., Fuji Kosan Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0119] Examples of the liquid polymer include liquid diene-based polymers (liquid rubbers) and liquid farnesene-based polymers that are liquid at 25°C. Examples of liquid rubber include liquid styrene-butadiene copolymers (liquid SBRs), liquid butadiene polymers (liquid BRs), liquid isoprene polymers (liquid IRs), liquid styrene-isoprene copolymers (liquid SIRs), liquid styrene-butadiene-styrene block copolymers (liquid SBS block polymers), and liquid styrene-isoprene-styrene block copolymers (liquid SIS block polymers). The terminals or main chains of these may be modified with polar groups. Hydrogenated versions of these compounds can also be used.

[0120] The liquid diene polymer has a weight average molecular weight (Mw) of 1.0×10 in terms of polystyrene as measured by gel permeation chromatography (GPC). 3 ~5.0×10 4 Preferably, it is 3.0 × 10 3 ~1.5×10 4 The lower or upper limit of Mw of the liquid diene polymer may be 4,500 or 8,500. In this specification, the Mw of the liquid diene polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0121] As the liquid diene polymer, for example, products available from Sartomer Co., Ltd., Kuraray Co., Ltd., etc. can be used.

[0122] The resin may be a resin commonly used in tire compounds, and may be liquid or solid at 25°C. Examples include aromatic vinyl polymers, coumarone-indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, and acrylic resins. The resin may also be a hydrogenated resin (hydrogenated resin). These may be used alone or in combination of two or more. The resin itself may also be a copolymer of monomer components derived from multiple sources. Among these, aromatic vinyl polymers, petroleum resins, terpene resins, and hydrogenated resins thereof are preferred.

[0123] When a resin that is solid at 25° C. is used, the softening point of the resin is preferably 50° C. or higher, more preferably 55° C. or higher, even more preferably 60° C. or higher, and particularly preferably 85° C. or higher. Also, the softening point is preferably 160° C. or lower, more preferably 150° C. or lower, even more preferably 140° C. or lower, and particularly preferably 100° C. or lower. Within the above range, better effects tend to be obtained. When the resin is liquid at 25°C, the softening point is preferably 20°C or lower, more preferably 10°C or lower, and even more preferably 0°C or lower. In the case of hydrogenated resins, it is desirable that the softening point is the same as above. The softening point of the resin is the temperature at which the ball drops when the softening point specified in JIS K6220-1:2001 is measured using a ring and ball softening point tester.

[0124] The aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a constituent unit. For example, it may be a resin obtained by polymerizing α-methylstyrene and / or styrene, and specifically may be a homopolymer of styrene (styrene resin), a homopolymer of α-methylstyrene (α-methylstyrene resin), a copolymer of α-methylstyrene and styrene, or a copolymer of styrene and another monomer.

[0125] The coumarone-indene resin is a resin containing coumarone and indene as the main monomer components constituting the resin skeleton (main chain). Other monomer components contained in the skeleton besides coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0126] The coumarone resin is a resin containing coumarone as a main monomer component constituting the skeleton (main chain) of the resin.

[0127] The indene resin is a resin containing indene as a main monomer component constituting the skeleton (main chain) of the resin.

[0128] The phenolic resin may be a known polymer obtained by reacting phenol with an aldehyde such as formaldehyde, acetaldehyde, or furfural in the presence of an acid or alkali catalyst. Of these, those obtained by reacting with an acid catalyst (such as novolac phenolic resin) are preferred.

[0129] Examples of the rosin resin include rosin-based resins such as natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

[0130] Examples of the petroleum resin include C5 resin, C9 resin, C5 / C9 resin, dicyclopentadiene (DCPD) resin, C9 / DCPD resin, and hydrogenated versions of these. Of these, DCPD resin, hydrogenated DCPD resin, C9 / DCPD resin, and C9 / hydrogenated DCPD resin are preferred.

[0131] The terpene resin is a polymer containing terpene as a structural unit. Examples include polyterpene resins obtained by polymerizing terpene compounds and aromatic-modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds. Examples of aromatic-modified terpene resins include terpene phenol resins made from terpene compounds and phenolic compounds, terpene styrene resins made from terpene compounds and styrene compounds, and terpene phenol styrene resins made from terpene compounds, phenolic compounds, and styrene compounds. Examples of terpene compounds include α-pinene and β-pinene, phenolic compounds include phenol and bisphenol A, and aromatic compounds include styrene compounds (styrene, α-methylstyrene, etc.). Among these, aromatic-modified terpene resins are preferred.

[0132] The acrylic resin is a polymer containing an acrylic monomer as a constituent unit. For example, a styrene-acrylic resin having a carboxyl group and obtained by copolymerizing an aromatic vinyl monomer component with an acrylic monomer component can be used. Among them, a solvent-free carboxyl-containing styrene-acrylic resin can be preferably used.

[0133] Examples of the resins that can be used include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, ExxonMobil, KRATON, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0134] From the viewpoint of sustainability, it is desirable to use the above-mentioned plant-derived plasticizers such as plant-derived oils and farnesene-based polymers as the plasticizer.

[0135] Farnesene polymers are polymers obtained by polymerizing farnesene and contain structural units based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene), but (E)-β-farnesene, which has the following structure, is preferred. [ka]

[0136] The farnesene polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer). These may be used alone or in combination of two or more. Among these, a copolymer of farnesene and a vinyl monomer is preferred.

[0137] Examples of vinyl monomers include aromatic vinyl compounds such as styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5-tert-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-tert-butylstyrene, 3-tert-butylstyrene, 4-tert-butylstyrene, vinylxylene, vinylnaphthalene, vinyltoluene, vinylpyridine, diphenylethylene, and tertiary amino group-containing diphenylethylene, as well as conjugated diene compounds such as butadiene and isoprene. These may be used alone or in combination of two or more. Among these, butadiene is preferred. That is, the farnesene-vinyl monomer copolymer is preferably a copolymer of farnesene and butadiene (farnesene-butadiene copolymer).

[0138] In the farnesene-vinyl monomer copolymer, the copolymerization ratio by mass of farnesene to vinyl monomer (farnesene / vinyl monomer) is preferably 40 / 60 to 90 / 10.

[0139] The farnesene polymer preferably has a weight average molecular weight (Mw) of 3,000 or more and 300,000 or less. The Mw of the farnesene polymer is preferably 8,000 or more, more preferably 10,000 or more, and is preferably 100,000 or less, more preferably 60,000 or less, and even more preferably 50,000 or less. Within the above ranges, the effects tend to be more favorably obtained.

[0140] The farnesene-based polymer may be either a liquid or solid at 25° C. Among these, a liquid farnesene-based polymer that is a liquid at 25° C. is preferred.

[0141] In the rubber composition, the content of the plasticizer (total amount of plasticizer) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. Within the above range, better effects tend to be obtained. The plasticizer content includes the amount of oil and resin contained in the oil-extended rubber and resin-extended rubber.

[0142] In the rubber composition, the content of the solid plasticizer in a solid state at 25° C. is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0143] In the rubber composition, the content of the resin in a solid state at 25° C. is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0144] In the rubber composition, the content of the liquid plasticizer in a liquid state at 25°C is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. Within the above range, better effects tend to be obtained. The content of the liquid plasticizer includes the amount of oil contained in the oil-extended rubber and the amount of liquid resin in the resin-extended rubber extended with the liquid resin.

[0145] In the rubber composition, the oil content is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, better effects tend to be obtained. The oil content includes the amount of oil contained in the oil-extended rubber.

[0146] In particular, the rubber composition preferably further contains a modified polymer modified with a boronic acid compound. From the viewpoint of obtaining a greater effect, the boronic acid compound is preferably a boronic acid compound represented by the above formula (1). The preferred form of formula (1) is as described above.

[0147] The reason why the above-mentioned effects are obtained is not entirely clear, but it is presumed that the following mechanism is involved. When a modified polymer obtained by reacting a polymer with a boronic acid compound is dried, it undergoes reversible dehydration condensation with three molecules to form boroxine (boroxine crosslinks). Then, upon contact with water, the formed boroxine crosslinks decompose. Thus, upon drying, a polymer with boroxine crosslinks is formed, while upon swelling with water, the boroxine crosslinks decompose, forming the modified polymer. Therefore, the modified polymer, together with the modified silica, can exhibit reversible changes in physical properties due to water. For example, when a rubber composition containing the modified polymer is used in a tire, the elastic modulus decreases upon contact with water, further increasing loss on wet roads and further improving wet grip performance.

[0148] From the viewpoint of obtaining even more effective effects, the above boronic acid compound is preferably a phenylboronic acid compound represented by the following formula (2). [ka] (R 11are the same or different, and are monovalent hydrocarbon groups which may have a substituent and may contain a heteroatom. n is an integer of 1 to 5.

[0149] In equation (2), R 11 Examples of the monovalent hydrocarbon group constituting the skeleton of R include linear, cyclic, or branched alkyl groups, alkenyl groups, aryl groups, and aralkyl groups, with alkyl groups being particularly preferred. 11 The number of carbon atoms is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and is preferably 30 or less, more preferably 20 or less, even more preferably 10 or less, and particularly preferably 6 or less. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, and a decyl group.

[0150] In the above formula (2), R 11 The substituents in 11 The substituent may be added to the skeleton of the monovalent hydrocarbon group that constitutes the skeleton, or may be introduced into the skeleton. The substituent is not particularly limited, and examples thereof include known groups. Examples include alkoxy groups having 1 to 4 carbon atoms, such as methoxy, ethoxy, and butoxy; halogen atoms, such as chlorine, bromine, iodine, and fluorine; aryl groups having 6 to 12 carbon atoms, such as phenyl, naphthyl, and biphenyl; and polar groups, such as oxo (=O), hydroxy, carboxyl, carbonyl, amino, acetyl, amide, imide, and thiol. From the viewpoint of reactivity with the polymer, the substituent is preferably a carboxyl, amino, or thiol group.

[0151] The substituent is preferably a group having a nitrogen atom, more preferably an amino group, from the viewpoint of obtaining a function of reversibly changing physical properties in response to water.

[0152] The reason why the above-mentioned effects are obtained is not entirely clear, but it is presumed that the following mechanism is involved. As described above, when a modified polymer reacted with a phenylboronic acid compound represented by formula (2) is dried, it undergoes reversible dehydration condensation of three molecules to form boroxine (boroxine crosslink). Then, upon contact with water, the resulting boroxine crosslink decomposes, presumably providing a water-induced reversible property change function. When ordinary phenylboroxine undergoes hydrolysis, heating is required for dehydration recondensation of three molecules. However, in the case of phenylboronic acid compounds containing nitrogen atoms, particularly phenylboronic acid compounds in which the nitrogen atom is located near the phenylboroxine group, dehydration recondensation of three molecules is possible even at room temperature. Therefore, it is presumed that the use of a modified polymer reacted with a phenylboronic acid compound represented by formula (2) can more effectively impart the function of reversible water-induced property change.

[0153] In the above formula (2), R 11 When the phenylboronic acid compound of formula (2) has a nitrogen atom, the nitrogen atom is preferably bonded to the boron atom of the phenylboronic acid compound of formula (2) via 1 to 6 carbon atoms, from the viewpoint of obtaining a function of reversibly changing physical properties in response to water. The number of carbon atoms is preferably 2 to 5, more preferably 2 to 4, and even more preferably 2 to 3.

[0154] R 11 The amino group of the substituent in the above formula (I) includes, for example, a primary amino group (-NH2), a secondary amino group (-NHR 1 ), tertiary amino group (-NR 1 R 2 ) are listed. 1 and R 2 is exemplified by an alkyl group, a phenyl group, an aralkyl group, etc., and the R 1 , R 2 The number of carbon atoms in the amino group is preferably 1 to 8. The amino group may be an ammonium salt group, such as a tertiary ammonium salt group or a quaternary ammonium salt group. The amino group may also be a divalent amino group. Examples of the divalent amino group include -N(H)-, -N(R 3 )-. 3 is exemplified by an alkyl group, a phenyl group, an aralkyl group, etc., and the R 3The number of carbon atoms in R is preferably 1 to 8. In the case of a divalent amino group, for example, R 11 is introduced into the skeleton of

[0155] R 11 Examples of the heteroatom in include a nitrogen atom, an oxygen atom, a sulfur atom, etc. Among these, a nitrogen atom is preferred from the viewpoint of obtaining a greater effect.

[0156] In formula (2), n is preferably 1 to 4, more preferably 1 to 3, even more preferably 1 or 2, and particularly preferably 1, from the viewpoint of obtaining a better effect.

[0157] From the viewpoint of obtaining a greater effect, among the phenylboronic acid compounds represented by the above formula (2), the compound represented by the following formula (2-1) is preferred. [ka] (R 21 and R 22 R are the same or different, and are divalent hydrocarbon groups which may have a substituent and may contain a heteroatom. 23 ~R 25 are the same or different and are hydrogen atoms or monovalent hydrocarbon groups which may have a substituent and may contain a heteroatom; and m is an integer of 1 to 5.

[0158] The reason why the above-mentioned effects are obtained is not entirely clear, but it is presumed that the following mechanism is involved. As mentioned above, when ordinary phenylboroxines are hydrolyzed, heating is required for the dehydration recondensation of three molecules, but in the case of the phenylboronic acid compound represented by formula (2-1), dehydration recondensation of three molecules is possible even at room temperature. Therefore, it is presumed that the use of modified polymers reacted with the compound represented by formula (2-1) can better impart the function of reversible changes in physical properties due to water.

[0159] In formula (2-1), R 21 and R 22The divalent hydrocarbon group constituting the skeleton of R may be linear, cyclic, or branched, and examples thereof include alkylene groups, alkenylene groups, cycloalkylene groups, cycloalkylalkylene groups, arylene groups, and aralkylene groups. 21 and R 22 The number of carbon atoms is preferably 1 to 30, more preferably 1 to 15, still more preferably 1 to 8, and particularly preferably 1 to 5. Specific examples include a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, and a hexamethylene group.

[0160] R 21 and R 22 The substituents in 21 and R 22 The substituent may be added to the skeleton of the divalent hydrocarbon group constituting the skeleton of the above group or may be introduced into the skeleton. 11 The substituents are the same as those of R 21 and R 22 Regarding the heteroatom in the above, for example, 11 The heteroatoms are the same as those in the above.

[0161] R 23 ~R 25 Examples of the monovalent hydrocarbon group constituting the skeleton of R 11 The monovalent hydrocarbon groups constituting the skeleton of R 23 ~R 25 The substituents in 23 ~R 25 The substituent may be added to the skeleton of the monovalent hydrocarbon group constituting the skeleton of the above group or may be introduced into the skeleton. 11 The substituents are the same as those of R 23 ~R 25 Regarding the heteroatom in the above, for example, 11 The heteroatoms are the same as those in the above.

[0162] Among them, R 23From the viewpoint of obtaining a greater effect, is preferably a hydrogen atom or a monovalent hydrocarbon group, and more preferably a hydrogen atom. R 24 From the viewpoint of obtaining a greater effect, is preferably a hydrogen atom or a monovalent hydrocarbon group, and more preferably a hydrogen atom. R 25 From the viewpoint of obtaining a greater effect, is preferably a hydrogen atom or a monovalent hydrocarbon group, and more preferably a hydrogen atom.

[0163] In formula (2-1), m is preferably 1 to 4, more preferably 1 to 3, still more preferably 1 or 2, and particularly preferably 1, from the viewpoint of obtaining a better effect.

[0164] The polymer constituting the skeleton of the modified polymer can be a liquid polymer (such as a liquid resin, a liquid diene-based polymer, or a liquid farnesene-based polymer) that is in a liquid state at 25° C. The liquid polymer is the same as that described above.

[0165] The polymer may also be a resin (a resin that is in a solid state at 25°C). The resin (resin in a solid state at 25° C.) is the same as that described above.

[0166] From the viewpoint of reactivity with the phenylboronic acid compound represented by the formula (2), the polymer is preferably a polymer having a functional group, such as the functional groups described above, and among these, an epoxy group, an amino group, or a carboxyl group is preferred.

[0167] The reaction process between a boronic acid compound (particularly, a phenylboronic acid compound represented by the above formula (2)) and the polymer is not particularly limited, and known methods can be used. The reaction may be carried out in a solvent such as an organic solvent in water, or without a solvent. The solvent is not particularly limited, but is preferably one in which both the boronic acid compound and the polymer are easily soluble. Specific examples of the solvent include those mentioned above. The reaction temperature and time may be appropriately set depending on the boronic acid compound and the polymer, so that the reaction proceeds at the temperature and time. The reaction between the boronic acid compound and the polymer can also be carried out by kneading the boronic acid compound, the polymer, and, if necessary, other components, thereby producing a modified polymer modified with the boronic acid compound.

[0168] The modified polymer may be either a modified polymer in a solid state at 25°C or a modified polymer in a liquid state at 25°C. Examples of modified polymers that are in a solid state at 25°C include modified polymers of polymers that are in a solid state at room temperature (25°C), such as the above-mentioned resins. Examples of modified polymers that are liquid at 25°C include modified polymers of liquid polymers that are liquid at room temperature (25°C), such as the above-mentioned liquid resins, liquid diene polymers, and liquid farnesene polymers.

[0169] In the rubber composition, the content of the modified polymer modified with a boronic acid compound is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, still more preferably 12.7 parts by mass or more, still more preferably 15 parts by mass or more, and still more preferably 20 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less. Within the above range, better effects tend to be obtained. In addition, when the modified polymer modified with the above-mentioned boronic acid compound is produced by kneading the above-mentioned boronic acid compound and the above-mentioned polymer in a rubber composition, the content of the modified polymer modified with the above-mentioned boronic acid compound in the rubber composition can be considered to be the sum of the amount of the above-mentioned boronic acid compound and the amount of the above-mentioned polymer added to the rubber composition.

[0170] The rubber composition may further contain vulcanized rubber particles. The vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the standpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. These may be used alone or in combination of two or more types.

[0171] The vulcanized rubber particles are not particularly limited, and may be unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0172] As commercially available vulcanized rubber particles, for example, products from Lehigh Corporation, Muraoka Rubber Industries Co., Ltd., etc. can be used.

[0173] In the rubber composition, the content of the vulcanized rubber particles is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0174] The rubber composition preferably contains an antioxidant from the viewpoints of crack resistance, ozone resistance, and the like.

[0175] The antioxidant is not particularly limited, and examples thereof include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N,N'-ditolyl-p-phenylenediamine. p-phenylenediamine antioxidants such as N-isopropyl-N'-phenyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products that can be used include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, etc.

[0176] In the rubber composition, the content of the antioxidant is preferably 0.2 parts by mass or more, more preferably 2.0 parts by mass or more, even more preferably 2.8 parts by mass or more, and still more preferably 3.4 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 10.0 parts by mass or less, more preferably 6.0 parts by mass or less.

[0177] The rubber composition preferably contains stearic acid. In the rubber composition, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2.0 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0178] As the stearic acid, conventionally known products can be used, for example, products available from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc.

[0179] The rubber composition preferably contains zinc oxide. In the rubber composition, the amount of zinc oxide per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, even more preferably 2.0 parts by mass or more, and still more preferably 2.2 parts by mass or more, and is preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less.

[0180] As the zinc oxide, conventionally known products can be used, for example, products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0181] The rubber composition may contain wax. In the rubber composition, the wax content is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 1.6 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 8.0 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0182] The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used. Examples include mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to this embodiment does not contain stearic acid. Waxes that can be used include those commercially available from, for example, Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., Ltd., etc. These waxes may be used alone or in combination of two or more.

[0183] It is preferable to compound sulfur as a crosslinking agent in the rubber composition, in order to form appropriate crosslinked chains in polymer chains and impart good performance.

[0184] The rubber composition preferably contains sulfur. In the rubber composition, the sulfur content is 1.0 part by mass or more, preferably 1.35 parts by mass or more, more preferably 2.0 parts by mass or more, and even more preferably 2.5 parts by mass or more, per 100 parts by mass of the rubber component. The sulfur content is preferably 7.0 parts by mass or less, more preferably 5.0 parts by mass or less, and even more preferably 4.0 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0185] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. Commercially available products include those from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more.

[0186] The rubber composition preferably contains a vulcanization accelerator. In the rubber composition, the content of the vulcanization accelerator is not particularly limited and may be freely determined according to the desired vulcanization rate and crosslink density, but is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and even more preferably 1.0 part by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, even more preferably 5.0 parts by mass or less, and still more preferably 4.6 parts by mass or less.

[0187] The type of vulcanization accelerator is not particularly limited, and commonly used ones can be used. Examples of the vulcanization accelerator include benzothiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. These may be used alone or in combination of two or more. Among these, sulfenamide-based, guanidine-based and benzothiazole-based vulcanization accelerators are preferred.

[0188] In addition to the above components, the rubber composition may also contain compounding agents generally used in the tire industry, such as a mold release agent, as appropriate.

[0189] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. As a method for obtaining the above-mentioned compound from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0190] The above rubber composition is obtained by kneading the above components using a rubber kneading device such as an open roll or a Banbury mixer, and then crosslinking the components, thereby obtaining a crosslinked rubber composition.

[0191] As for kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is preferably 50°C or higher, more preferably 80°C or higher, and preferably 200°C or lower, more preferably 190°C or lower. The kneading time is preferably 30 seconds or higher, more preferably 1 minute or higher, and preferably 30 minutes or lower. In the finish kneading step in which the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is preferably 20°C or higher, and preferably 100°C or lower, more preferably 80°C or lower. The composition kneaded with the vulcanizing agent and vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is preferably 120°C or higher, more preferably 140°C or higher, and preferably 200°C or lower, more preferably 180°C or lower.

[0192] The rubber composition can be used for tires, shoe soles, flooring materials, vibration-proof materials, seismic isolation materials, butyl frames, belts, hoses, packings, drug stoppers, and other rubber industrial products, etc. In particular, it is preferable to use the rubber composition as a rubber composition for tires because it has excellent tire performance such as wet grip performance.

[0193] The tire components to which the rubber composition is applied are not particularly limited, and examples thereof include any tire components such as cap tread, sidewall, base tread, bead apex, clinch apex, inner liner, undertread, breaker topping, bright topping, etc. Among these, the rubber composition is preferably applied to cap tread because of its excellent wet grip performance.

[0194] <Tires> The rubber composition can be suitably used for tires. Examples of tires include pneumatic tires and non-pneumatic tires, with pneumatic tires being preferred. In particular, the rubber composition can be suitably used as summer tires, winter tires (studless tires, snow tires, studded tires, etc.), all-season tires, etc. Tires can be used for passenger car tires, large passenger car tires, large SUV tires, heavy-duty tires for trucks, buses, etc., light truck tires, motorcycle tires, racing tires (high-performance tires), etc. In particular, the rubber composition can be suitably used for passenger car tires and light truck tires.

[0195] A tire is manufactured by a conventional method using the rubber composition. For example, a rubber composition containing various materials is extruded in an unvulcanized state to match the shape of a tire component, and molded together with other tire components in a tire building machine by a conventional method to form an unvulcanized tire, which is then heated and pressurized in a vulcanizer to manufacture a tire. [Example]

[0196] Below, examples (embodiments) that are considered preferable for implementation will be shown, but the scope of the present invention is not limited to the examples.

[0197] The various chemicals used in tire manufacturing are summarized below. If necessary, the chemicals may be refined according to standard methods.

[0198] <Synthesis of Boronic Acid Compound-Modified Silica 1> Modified silica modified with a phenylboronic acid compound is synthesized according to the synthesis route shown in FIG. Specifically, the synthesis is carried out by the following method.

[0199] Phenylboronic acid compound A is added to a methanol solution of amine-modified silica, and the mixture is stirred at 0°C for 1 hour, followed by overnight stirring at room temperature. The temperature is then returned to 0°C, and sodium borohydride (NaBH4) is added in small portions, followed by stirring at room temperature for 4 hours. After stirring is complete, the residue is collected by suction filtration and dried under reduced pressure for 1 hour to obtain boronic acid compound-modified silica.

[0200] Intermediates and compounds in the above synthesis 13 The C-NMR spectrum is shown in Figure 2 (Figure 2(a): intermediate, Figure 2(b): synthesized product). In Figure 2, S is a spinning sideband, and the other peaks can be assigned as shown in the figure. The peak 4, which can be seen in the spectrum of the intermediate, has almost completely disappeared in the spectrum of the synthesized product, confirming that the intermediate was reduced by sodium borohydride (NaBH4) and the target product was synthesized. In FIG. 2, Si represents silica.

[0201] The amine-modified silica and the synthesized boronic acid compound-modified silica were subjected to thermogravimetric analysis (TGA) using a TA Instruments TGA Q500. The results of the TGA are shown in Figure 3. The results in Figure 3 indicate that the amount of boronic acid compound added to the boronic acid compound-modified silica is approximately 0.26 mmol / g.

[0202] <Synthesis of Boronic Acid Compound-Modified Silica 2> Modified silica 1 modified with a phenylboronic acid compound (boronic acid compound-modified silica 1) and modified silica 2 modified with a phenylboronic acid compound (boronic acid compound-modified silica 2) are synthesized according to the synthesis route shown in FIG. 8. Specifically, the synthesis is carried out by the following method.

[0203] Phenylboronic acid compound A is added to a methanol solution of amine-modified silica, and the mixture is stirred at 0°C for 1 hour, followed by stirring at room temperature overnight. The residue is then collected by suction filtration and dried under reduced pressure for 1 hour to obtain boronic acid compound-modified silica 1. Boronic acid compound-modified silica 1 is dispersed in methanol, and then the temperature is returned to 0°C. Sodium borohydride (NaBH4) is added little by little and the mixture is stirred at room temperature for 4 hours. After stirring is complete, the residue is collected by suction filtration and dried under reduced pressure for 1 hour to obtain boronic acid compound-modified silica 2.

[0204] In the above synthesis, the boronic acid compound-modified silica 1 and the boronic acid compound-modified silica 2 13 The C-NMR spectra of the intermediates and the synthesized product of the above-mentioned synthesis 1 of the boronic acid compound-modified silica shown in Figure 2 are shown. 13 The C-NMR spectra are similar to those shown in Figure 2(a): Boronic acid compound-modified silica 1, and Figure 2(b): Boronic acid compound-modified silica 2. In Figure 2, S denotes a spinning sideband, and the other peaks can be assigned as shown. The peak 4, which can be seen in the spectrum of boronate compound-modified silica 1, almost completely disappears in the spectrum of boronate compound-modified silica 2, confirming that boronate compound-modified silica 1 was reduced by sodium borohydride (NaBH4) to synthesize boronate compound-modified silica 2. In FIG. 2, Si represents silica.

[0205] Furthermore, the amine-modified silica and the boronic acid compound-modified silica 1 were subjected to thermogravimetric analysis (TGA) using a TA Instruments TGA Q500. The results of the TGA are shown in Figure 9. The results in Figure 9 indicate that the amount of boronic acid compound added to the boronic acid compound-modified silica 1 was approximately 0.2 mmol / g.

[0206] As described above, it is clear that it is possible to synthesize modified silica modified with a boronic acid compound (boronic acid compound-modified silica).

[0207] When boronic acid compound-modified silica is dried to a constant weight under normal temperature and pressure conditions, and then repeatedly immersed in water to moisten it, it undergoes reversible dehydration condensation of three molecules to produce boroxine (boroxine crosslinks), and then, when it comes into contact with water, the resulting boroxine crosslinks are thought to decompose. Therefore, it is thought that boronic acid compound-modified silica has the ability to reversibly change its physical properties when exposed to water.

[0208] <Synthesis of phenylboronic acid compounds> A phenylboronic acid compound C (a phenylboronic acid compound represented by formula (2)) is synthesized according to the synthetic route shown in FIG. Specifically, the synthesis is carried out by the following method.

[0209] Phenylboronic acid compound B is reacted with an amine compound in methanol at room temperature overnight, reduced with sodium borohydride (NaBH4), and deprotected with hydrochloric acid (HCl) to synthesize phenylboronic acid compound C.

[0210] The composite shown in Figure 5 1 From the H-NMR spectrum, it is found that phenylboronic acid compound C (phenylboronic acid compound represented by formula (2)) has been synthesized.

[0211] <Synthesis of modified polymer> A modified polymer (modified with a phenylboronic acid compound represented by formula (2)) is synthesized according to the synthesis route shown in FIG. Specifically, the synthesis is carried out by the following method.

[0212] (Synthesis of modified polymers) Carboxyl-modified liquid polyisoprene and phenylboronic acid compound C are added to chloroform, and a dehydration condensation reaction is carried out using EDC / HOBt to obtain a modified polymer. The modified polymer is purified by washing with methanol.

[0213] IR spectrum shown in Figure 7,1 The H-NMR spectrum shows that phenylboronic acid compound C (phenylboronic acid compound represented by formula (2)), liquid polyisoprene modified with a carboxyl group, and liquid polyisoprene modified with phenylboronic acid compound C (modified polymer) were synthesized.

[0214] <Synthesis of amine-modified liquid butadiene polymer> The liquid butadiene polymer is dissolved in dichloromethane (CHCl), and 2-aminoethanethiol and the initiator 2,2-dimethoxy-2-phenylacetophenone are added. The mixture is exposed to a lamp (365 nm, 250 W) under nitrogen for 2 hours. The lamp is then turned off, and the reaction solution is washed several times with salt water to remove unreacted 2-aminoethanethiol. The solution is then centrifuged to dryness, yielding the desired viscous liquid product (amine-modified liquid butadiene polymer).

[0215] The IR spectrum shown in FIG. 10 indicates that an amine-modified liquid butadiene polymer was synthesized.

[0216] The following materials are used in the synthesis of the boronic acid compound-modified silica in Figure 1, the boronic acid compound-modified silica 1 and the boronic acid compound-modified silica 2 in Figure 8, the synthesis of the phenylboronic acid compound C in Figure 4, the synthesis of the modified polymer in Figure 6, and the synthesis of the above-mentioned amine-modified liquid butadiene polymer. Amine-modified silica: 3-aminopropyl silica gel (Tokyo Chemical Industry Co., Ltd., loading: 0.6 to 1.3 mmol / g) Phenylboronic acid compound A: 2-formylphenylboronic acid (Fujifilm Wako Pure Chemical Industries, Ltd.) Sodium borohydride (NaBH4): Fujifilm Wako Pure Chemical Industries, Ltd. Methanol: Fujifilm Wako Pure Chemical Industries, Ltd. Phenylboronic acid compound B: manufactured by Boron Molecular Pty Limited Amine compound: Combi-Blocks Hydrochloric acid (HCl): Fujifilm Wako Pure Chemical Industries, Ltd. Carboxyl-modified liquid polyisoprene (LIR-410 manufactured by Kuraray Co., Ltd., molecular weight: 30,000, number of carboxyl groups per molecule: 10, glass transition temperature: -59°C) EDC: 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (Tokyo Chemical Industry Co., Ltd.) HOBt: 1-hydroxybenzotriazole (Tokyo Chemical Industry Co., Ltd.) Liquid butadiene polymer: L-BR-361 (Kuraray Co., Ltd.) Dichloromethane (CH2Cl2): Fujifilm Wako Pure Chemical Industries, Ltd. 2-Aminoethanethiol: manufactured by Tokyo Chemical Industry Co., Ltd. 2,2-Dimethoxy-2-phenylacetophenone: Fujifilm Wako Pure Chemical Industries, Ltd.

[0217] <Production of test tires> According to the formulations in Tables 1 to 3, materials other than sulfur and vulcanization accelerator are kneaded to obtain a kneaded mixture. To the above kneaded material, sulfur and a vulcanization accelerator are added according to the formulations in Tables 1 to 3, and the mixture is kneaded at 70°C for 8 minutes to obtain an unvulcanized rubber composition. The unvulcanized rubber composition is extruded into the shape of a cap layer, and is laminated together with other tire components on a tire building machine to form an unvulcanized tire. The unvulcanized tire is press-vulcanized at 170°C for 20 minutes to obtain a test tire (size 195 / 65R15).

[0218] Tables 1 to 3 show the results of calculations based on the following evaluation methods, assuming test tires obtained from compositions whose formulations were changed according to Tables 1 to 3. The reference comparative examples are as follows: Table 1: Comparative Example 1-1 Table 2: Comparative Example 2-1 Table 3: Comparative Example 3-1

[0219] SBR: HPR850 manufactured by JSR Corporation (modified SBR, styrene content: 27.5% by mass, vinyl bond content: 59.0% by mass) BR: BR730 manufactured by JSR Corporation (cis content: 95% by mass) NR:TSR20 Carbon black: Diablack I (N220, N2SA: 114m) manufactured by Mitsubishi Chemical Corporation 2 / g) Silica: Evonik Ultrasil VN3 (N2SA: 175 ml 2 / g) Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Boronic acid compound-modified silica: Synthesized in "Synthesis of Boronic acid compound-modified silica 1" above Boronic acid compound-modified silica 1: Synthesized in "Synthesis of boronic acid compound-modified silica 2" above Boronic acid compound-modified silica 2: Synthesized in "Synthesis of boronic acid compound-modified silica 2" above Modified polymer: Synthesized as described above in "Synthesis of modified polymer" Amine-modified liquid butadiene polymer: Synthesized as described above in "Synthesis of amine-modified liquid butadiene polymer" Phenylboronic acid compound: 2-formylphenylboronic acid (Fujifilm Wako Pure Chemical Industries, Ltd.) Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Antioxidant: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: NOF Corporation's "Tsubaki" stearic acid Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. Sulfur: Powdered sulfur (5% oil content) manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noccela D (diphenyl guanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccela NS (N-tert-butyl-2-benzothiazylsulfenamide (TBBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0220] <Wet grip performance> Each test tire is fitted to all wheels of a vehicle (domestic FF 2000cc) and driven 10 laps around a wet road course, during which 20 test drivers rate the braking performance on wet roads on a 5-point scale from 1 to 5. The higher the score, the better the performance. The scores of the 20 drivers are added together and the total score of the reference comparison example is set to 100, creating an index. The higher the index, the better the wet grip performance.

[0221] [Table 1]

[0222] [Table 2]

[0223] [Table 3]

[0224] The present invention (1) is a modified silica modified with a boronic acid compound.

[0225] The present invention (2) is a rubber composition containing the modified silica according to the present invention (1) and a rubber component.

[0226] The present invention (3) is the rubber composition according to the present invention (2), wherein the rubber component contains a modified rubber modified with a boronic acid compound.

[0227] The present invention (4) is the rubber composition according to the present invention (2) or (3), further comprising a modified polymer modified with a boronic acid compound.

[0228] The present invention (5) is a tire having tire components made of a rubber composition in any combination with any of the present inventions (2) to (4).

Claims

1. Modified silica modified with boronic acid compounds.

2. A rubber composition comprising the modified silica according to claim 1 and a rubber component.

3. The rubber composition according to claim 2, wherein the rubber component contains a modified rubber modified with a boronic acid compound.

4. The rubber composition according to claim 2, further comprising a modified polymer modified with a boronic acid compound.

5. A tire having tire components made of the rubber composition according to claim 2.

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