Nitrile oxide compounds and polymers containing ionic functional groups

Abstract

Provided are: a novel nitrile oxide compound having both a nitrile oxide group capable of reacting with various unsaturated polymers and an ionic functional group; an ionic-functional-group-containing polymer containing the nitrile oxide compound introduced thereinto; and a rubber composition and a tire each including or obtained using the ionic-functional-group-containing polymer.

Description

[Technical Field]

[0001] The present disclosure relates to a nitrile oxide compound, an ionic functional group-containing polymer, a rubber composition, and a tire. [Background technology]

[0002] Rubbers having ionic molecules have been disclosed as polymers with various properties, and for example, it has been proposed to introduce a unit containing carboxylic acid into styrene-butadiene rubber. However, it is generally difficult to adjust the amount of ionic functional groups such as carboxylic acid groups in a polymer or to introduce ionic functional groups into various polymers. Summary of the Invention [Problem to be solved by the invention]

[0003] In response to the demand for a technique for easily introducing a low molecular weight compound having an ionic functional group such as a carboxylic acid group into a polymer, the present inventors focused on nitrile oxide compounds and synthesized a novel nitrile oxide compound having a nitrile oxide group and an ionic functional group, and discovered that this novel compound can react with various unsaturated polymers, does not require any particular catalyst during synthesis, and can suppress the generation of by-products, thereby completing the present disclosure.

[0004] The present disclosure aims to solve the above-mentioned problems and to provide a novel nitrile oxide compound having a nitrile oxide group and an ionic functional group that can react with various unsaturated polymers, an ionic functional group-containing polymer into which the nitrile oxide compound has been introduced, and a rubber composition and a tire that use the ionic functional group-containing polymer. [Means for solving the problem]

[0005] The present disclosure relates to nitrile oxide compounds having a nitrile oxide group and an ionic functional group. [Effects of the Invention]

[0006] According to the present disclosure, it is possible to provide a novel nitrile oxide compound having a nitrile oxide group and an ionic functional group, which is capable of reacting with various unsaturated polymers because it is a nitrile oxide compound having a nitrile oxide group and an ionic functional group, an ionic functional group-containing polymer into which the nitrile oxide compound has been introduced, and a rubber composition and a tire using the ionic functional group-containing polymer. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a method for synthesizing a nitrile oxide compound having a nitrile oxide group and an ionic functional group. [Figure 2] 1 shows an example of 1H-NMR (proton NMR) spectra of compounds C, D, and E in the total path of FIG. 1. [Figure 3] 1 shows an example of the IR spectra of compounds D and E in the combined pathway of FIG. 1. [Figure 4] This is an example of synthesis showing that a nitrile oxide compound having a nitrile oxide group and an ionic functional group reacts with a polymer having a double bond to synthesize a polymer having an ionic functional group. [Figure 5] 5 is an example of a 1H-NMR (proton NMR) spectrum of the polymer in the total path of FIG. 4. [Figure 6] FIG. 1 is a schematic diagram illustrating an example of a method for synthesizing a nitrile oxide compound having a nitrile oxide group and an ionic functional group. [Figure 7] FIG. 1 is a schematic diagram illustrating an example of a method for synthesizing a nitrile oxide compound having a nitrile oxide group and an ionic functional group. [Figure 8] 1 shows an example of the IR spectrum of Example 1-1 using SSBR1-4 (SBR containing an ionic functional group), and Comparative Example 1-1 using the corresponding SSBR1, as well as an example of the difference spectrum therebetween. DETAILED DESCRIPTION OF THE INVENTION

[0008] <Nitrile oxide compounds> The present disclosure relates to a novel nitrile oxide compound having a nitrile oxide group and an ionic functional group. The nitrile oxide compound can react with various polymers, allowing for the easy introduction of ionic functional groups into polymers to provide ionic functional group-containing polymers. Furthermore, the synthesis of the nitrile oxide compound does not require a catalyst, and the generation of by-products can be suppressed.

[0009] In the nitrile oxide compound having a nitrile oxide group and an ionic functional group, the nitrile oxide group is a group represented by the following formula: The nitrile oxide compound may be a compound having one nitrile oxide group or two or more nitrile oxide groups.

[0010] [ka]

[0011] In the nitrile oxide compound having a nitrile oxide group and an ionic functional group, the ionic functional group may be a cationic functional group or an anionic functional group. The ionic functional group is preferably introduced at the terminal of the nitrile oxide compound. The nitrile oxide compound may be a compound having one ionic functional group or two or more ionic functional groups. Furthermore, the ionic functional group in the nitrile oxide compound may be one type or two or more types.

[0012] Examples of cationic functional groups include basic functional groups. Examples of basic functional groups include amino groups, imino groups (=NH), ammonium bases, and heterocyclic groups having a basic nitrogen atom. Examples of amino groups include primary amino groups (-NH), secondary amino groups (-NHR 1 ), tertiary amino group (-NR 1 R 2 ) is acceptable. R 1 and R 2 R is an alkyl group, a phenyl group, an aralkyl group, etc. 1 and R 2The number of carbon atoms is preferably 1 to 8. Examples of the ammonium base include tertiary ammonium bases and quaternary ammonium bases. Examples of the heterocyclic group having a basic nitrogen atom include nitrogen-containing heterocyclic groups such as pyridine, pyrimidine, pyrazine, imidazole, thiol-containing imidazole, triazole, and thiazole. Of these, amino groups (primary amino, secondary, and tertiary amino groups) are preferred.

[0013] Examples of anionic functional groups include halogen groups and acidic functional groups. Examples of halogen groups include fluoro groups, chloro groups, bromo groups, and iodo groups. Examples of acidic functional groups include hydroxyl groups, carboxylic acid groups, sulfonic acid groups, sulfate groups, phosphonic acid groups, phosphate groups, phosphinic acid groups, maleic acid groups, acid anhydride groups (maleic anhydride groups, etc.), fumaric acid groups, itaconic acid groups, acrylic acid groups, methacrylic acid groups, and mercapto groups. Of these, carboxylic acid groups (carboxyl groups) are preferred.

[0014] The nitrile oxide compound is not particularly limited as long as it is a compound having a nitrile oxide group and an ionic functional group, and examples thereof include compounds represented by the following formula: XC≡N + -O - (In the formula, X represents a monovalent hydrocarbon group containing an ionic functional group.)

[0015] X is not particularly limited as long as it is a monovalent hydrocarbon group containing an ionic functional group. Examples of the ionic functional group contained in X include the same as the ionic functional group described above. The ionic functional group contained in X is preferably formed at the end of X, for example, so that X is a group represented by -(CH)-A (A: ionic functional group).

[0016] The monovalent hydrocarbon group in X (monovalent hydrocarbon group containing an ionic functional group) means a monovalent hydrocarbon group that constitutes the skeleton of X and in which an ionic functional group has been substituted with a hydrogen atom. For example, when X is a group represented by -(CH)-COOH (COOH: ionic functional group), the monovalent hydrocarbon group in X is -(CH)-H.

[0017] The monovalent hydrocarbon group for X includes substituted or unsubstituted monovalent hydrocarbon groups, which may be linear, branched, or cyclic, but are preferably cyclic. The monovalent hydrocarbon group for X may also contain a heteroatom. The substituent is not particularly limited, and examples thereof include known groups such as a hydroxyl group and a halogen group (such as -Cl or -Br). The heteroatom is not particularly limited, and examples thereof include oxygen and nitrogen. These substituents and heteroatoms may be present in one or more numbers.

[0018] The monovalent hydrocarbon group for X preferably has 3 or more carbon atoms, more preferably 6 or more carbon atoms, and preferably 30 or less, more preferably 26 or less, and even more preferably 20 or less carbon atoms.

[0019] Examples of the monovalent hydrocarbon group for X include a substituted or unsubstituted linear alkyl group, branched alkyl group, cyclic alkyl group, aryl group, and aralkyl group, which may contain a heteroatom. The monovalent hydrocarbon group for X may also be a group to which these substituted or unsubstituted linear alkyl groups, branched alkyl groups, cyclic alkyl groups, aryl groups, and aralkyl groups, which may contain a heteroatom, are bonded (such as a group to which a substituted or unsubstituted linear alkyl group, which may contain a heteroatom, and a substituted or unsubstituted aryl group, which may contain a heteroatom, are bonded).

[0020] In the monovalent hydrocarbon group represented by X, examples of substituted or unsubstituted linear or branched alkyl groups that may contain heteroatoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, 2-ethylhexyl, octyl, nonyl, decyl, and groups containing these heteroatoms. Examples of substituted or unsubstituted cyclic alkyl groups that may contain heteroatoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantyl, 1-ethylcyclopentyl, 1-ethylcyclohexyl, and groups containing these heteroatoms. Examples of substituted or unsubstituted aryl groups that may contain heteroatoms include phenyl, tolyl, xylyl, biphenyl, naphthyl, anthryl, phenanthryl, and groups containing these heteroatoms. Examples of the substituted or unsubstituted aralkyl group which may contain a heteroatom include a benzyl group, a phenethyl group, and groups containing these heteroatoms. Furthermore, examples of the monovalent hydrocarbon group for X include groups to which these groups are bonded (such as a group to which a substituted or unsubstituted pentyl group which may contain a heteroatom and a substituted or unsubstituted naphthyl group which may contain a heteroatom are bonded).

[0021] Among these, the monovalent hydrocarbon group for X is preferably a substituted or unsubstituted linear alkyl group which may contain a heteroatom, a substituted or unsubstituted aryl group which may contain a heteroatom, or a group in which a substituted or unsubstituted linear alkyl group which may contain a heteroatom is bonded to a substituted or unsubstituted aryl group which may contain a heteroatom.

[0022] The compound having a nitrile oxide group and an ionic functional group is preferably a compound having a cyclic structure, more preferably a compound having an aromatic ring. Specific examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a fluorene ring, a triphenylene ring, a naphthacene ring, a biphenyl ring, a bisphenol ring, and a terphenyl ring (three benzene rings may be connected in any manner). Among these, a compound having a benzene ring or a naphthalene ring is preferred, and a compound having a naphthalene ring is more preferred.

[0023] Suitable examples of the nitrile oxide compound having a nitrile oxide group and an ionic functional group include compounds represented by the following formula (compounds having a naphthalene ring).

[0024] [ka] (In the formula, A represents a monovalent ionic functional group, and Y represents a substituted or unsubstituted divalent hydrocarbon group which may contain a heteroatom.)

[0025] Examples of A (monovalent ionic functional group) include the monovalent ionic functional groups described above.

[0026] Y (a substituted or unsubstituted divalent hydrocarbon group which may contain a heteroatom) may be linear, branched, or cyclic. Examples of the heteroatom and substituent in Y include the heteroatoms and substituents described above. Y may have one or more of these substituents or heteroatoms.

[0027] The divalent hydrocarbon group for Y preferably has 1 or more carbon atoms, more preferably 2 or more carbon atoms, and even more preferably 3 or more carbon atoms, and preferably has 20 or less carbon atoms, more preferably 12 or less carbon atoms, and even more preferably 10 or less carbon atoms.

[0028] Examples of Y (a substituted or unsubstituted divalent hydrocarbon group which may contain a heteroatom) include a substituted or unsubstituted alkylene group, alkenylene group, cycloalkylene group, cycloalkylalkylene group, arylene group, aralkylene group, and oxyalkylene group which may contain a heteroatom.

[0029] Examples of substituted or unsubstituted alkylene groups that may contain heteroatoms include methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, octylene, nonylene, decylene, 1,2-propylene, and groups containing these heteroatoms. Examples of substituted or unsubstituted alkenylene groups that may contain heteroatoms include vinylene, 1-propenylene, 2-propenylene, and groups containing these heteroatoms. Examples of substituted or unsubstituted cycloalkylene groups that may contain heteroatoms include cyclohexylene and groups containing this heteroatom. Examples of substituted or unsubstituted cycloalkylalkylene groups that may contain heteroatoms include cyclohexylmethylene and groups containing this heteroatom. Examples of substituted or unsubstituted arylene groups that may contain heteroatoms include phenylene, tolylene, xylylene, and groups containing these heteroatoms. Examples of substituted or unsubstituted aralkylene groups which may contain a heteroatom include a benzylidene group and groups containing this heteroatom, etc. Examples of substituted or unsubstituted oxyalkylene groups which may contain a heteroatom include an oxyethylene group, an oxypropylene group, an oxybutylene group, an oxytetramethylene group, and groups containing these heteroatoms, etc.

[0030] The compound having a naphthalene ring represented by the above formula is one example of a preferred example, and the —C≡N + -O - The substitution positions of the group represented by -YA are not particularly limited, and may be any of the 1st to 8th positions. + -O - , -YA.

[0031] Next, a method for synthesizing the nitrile oxide compound having a nitrile oxide group and an ionic functional group will be described. Hereinafter, an example of a method for synthesizing the nitrile oxide compound having a nitrile oxide group and an ionic functional group will be described, but the nitrile oxide compound is not limited to those obtained by such a synthesis method, and includes compounds obtained by any synthesis method that can be synthesized.

[0032] First, a compound having a hydroxyl group and an aldehyde group is used as a starting material, and the compound having the hydroxyl group and the aldehyde group is reacted with a compound into which an ionic functional group can be introduced. If necessary, the group derived from the compound into which an ionic functional group can be introduced in the resulting substance is substituted with the ionic functional group.

[0033] Next, the aldehyde group in the prepared compound is converted to a group represented by -CH=N-OH, and the group represented by -CH=N-OH is further converted to -C≡N + -O - By converting the nitrile oxide compound into a group represented by the formula (I), a nitrile oxide compound having a nitrile oxide group and an ionic functional group can be synthesized.

[0034] The reaction process may be carried out in an organic solvent, in water, or without a solvent. The organic solvent is not particularly limited, but is preferably one in which both the reacting compound and the reactant compound are easily soluble. The organic solvent is not particularly limited, and examples thereof include toluene, mesitylene, chloroform (CHCl), alcohol, and THF (tetrahydrofuran). A catalyst may also be used, if necessary. The catalyst is not particularly limited, and examples thereof include DMF (N,N-dimethylformamide), DMSO (dimethyl sulfoxide), and triethylamine (TEA). The amounts of solvent and catalyst may be appropriately determined depending on the compound so that the reaction proceeds. The reaction temperature and time may also be appropriately determined depending on the compound so that the reaction proceeds. The reaction temperature may be, for example, 10 to 100°C, preferably 20 to 80°C, and the reaction time may be, for example, 1 to 200 hours, preferably 3 to 100 hours.

[0035] To explain a specific example of compound synthesis, for example, a nitrile oxide compound having a nitrile oxide group and an ionic functional group, represented by compound E, can be synthesized by the synthetic route shown in FIG.

[0036] First, compound A (a compound having a hydroxyl group and an aldehyde group) is used as the starting material, and compound A is reacted with a compound to which an ionic functional group can be introduced (Br-(CH2)5-C(=O)-O-CH2CH3) to obtain compound B. In the obtained compound B, -C(=O)-O-CH2CH3 (a group derived from the compound to which an ionic functional group can be introduced) is substituted with -C(=O)-OH (ionic functional group: carboxylic acid group) to obtain compound C.

[0037] The aldehyde group in the prepared compound C is converted to a group represented by -CH=N-OH to synthesize compound D. The group represented by -CH=N-OH in the obtained compound D is converted to -C≡N + -O - to synthesize compound E (a nitrile oxide compound having a nitrile oxide group and an ionic functional group).

[0038] Figure 2 shows the total pathway of compounds C, D, and E in Figure 1. 1 Figure 2 shows an example of a H-NMR (proton NMR) spectrum. Figure 3 shows an example of the IR spectrum of compounds D and E in the total route shown in Figure 1. The spectra in Figure 2 indicate that compounds C, D, and E have been synthesized, and the spectra in Figure 3 indicate that compounds D and E have been synthesized.

[0039] Furthermore, for example, a nitrile oxide compound having a nitrile oxide group and an ionic functional group, represented by Compound I, can be synthesized by the synthetic route shown in FIG.

[0040] First, compound A (a compound having a hydroxyl group and an aldehyde group) is used as the starting material, and compound A is reacted with a compound (Cl-(CH2)6-OH) to which an ionic functional group can be introduced to obtain compound F.

[0041] The aldehyde group in the compound F thus prepared is converted to -CH=N-OH to synthesize compound G. The -CH=N-OH in the resulting compound G is converted to -C≡N + -O - to obtain compound H (ionic functional group: hydroxyl group).

[0042] The -OH group (a group derived from a compound capable of introducing an ionic functional group) in the obtained compound H is replaced with -OC(=O)-CH(CH3)2-BR (ionic functional group: halogen group) to synthesize compound I (a nitrile oxide compound having a nitrile oxide group and an ionic functional group).

[0043] Furthermore, for example, a nitrile oxide compound having a nitrile oxide group and an ionic functional group, represented by compound e, can be synthesized by the synthetic route shown in FIG.

[0044] First, compound a (a compound having a hydroxyl group and an aldehyde group) is used as the starting material, and compound a is reacted with a compound to which an ionic functional group can be introduced (Br-CH2-Ph-C(=O)-O-CH3) to obtain compound b.

[0045] The group represented by -C(=O)-O-CH3 in the prepared compound b (a group derived from a compound capable of introducing an ionic functional group) is converted to -C(=O)-OH (ionic functional group: carboxylic acid group) to obtain compound c.

[0046] The aldehyde group in the compound c thus prepared is converted to -CH=N-OH to synthesize compound d. + -O - to synthesize compound e (a nitrile oxide compound having a nitrile oxide group and an ionic functional group).

[0047] <Polymer containing ionic functional groups> An ionic functional group-containing polymer obtained by reacting a nitrile oxide compound having a nitrile oxide group and an ionic functional group with a polymer is a modified polymer obtained by reacting a nitrile oxide compound having a nitrile oxide group and an ionic functional group with a polymer (e.g., a polymer having an unsaturated bond). Use of the ionic functional group-containing polymer improves tire performance, such as wet grip performance.

[0048] The mechanism by which the above-mentioned effects are obtained is not clear, but is presumed to be as follows. Nitrile oxide compounds having nitrile oxide groups and ionic functional groups can react with various unsaturated polymers, making it easy to add the nitrile oxide compounds to unsaturated polymers such as diene rubbers, allowing for the easy synthesis of polymers with ionic bond sites (sites where ionic bonds are formed). The content of ionic bond sites in the polymers can also be easily adjusted. For example, when diene rubbers incorporating the nitrile oxide compounds are used in rubber compositions for tires, upon contact with a wet road surface, the ionic bond sites dissociate, the crosslinking weakens, and the modulus of elasticity decreases. Therefore, when driving on wet roads, the contact area with the road surface increases, increasing friction and improving loss, which is presumably responsible for improved wet grip performance.

[0049] The method for reacting a nitrile oxide compound having a nitrile oxide group and an ionic functional group with a polymer can be any method that allows the reaction to occur. For example, the nitrile oxide compound and the polymer having an unsaturated bond can be dissolved or energy can be applied, as necessary, to cause a cycloaddition reaction between the nitrile oxide group and the carbon-carbon double bond in the main chain of the polymer, thereby allowing the reaction to proceed and produce a five-membered ring.

[0050] Examples of the polymer include polymers having a carbon-carbon double bond. Examples of the polymer having a carbon-carbon double bond include rubber components such as diene rubber. Examples of the 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). Other examples include butyl rubber and fluororubber. Among these, from the viewpoint of tire performance such as wet grip performance, SBR, BR, and isoprene rubber are preferred, and SBR and BR are more preferred.

[0051] The diene rubber may be an unmodified diene rubber or a modified diene rubber. The modified diene rubber may be any diene rubber having a functional group that interacts with a filler such as silica. Examples include terminal-modified diene rubbers (terminal-modified diene rubbers having the functional group at the terminal) in which at least one terminal of the diene rubber has been modified with a compound (modifier) having the functional group, main-chain-modified diene rubbers having the functional group at the main chain, main-chain-terminal-modified diene rubbers having the functional group at the main chain and at the terminals (for example, main-chain-terminal-modified diene rubbers having the functional group at the main chain and at least one terminal modified with the modifier), and terminal-modified diene rubbers modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having a hydroxyl group or epoxy group introduced therein.

[0052] 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.

[0053] 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.

[0054] The styrene content of the SBR is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. Within the above ranges, better tire performance such as wet grip performance tends to be obtained. In this specification, the styrene content of SBR is 1 It is calculated by H-NMR measurement.

[0055] The vinyl content of the SBR is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more. The vinyl content is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. Within the above range, tire performance such as wet grip performance tends to be better. The vinyl content (amount of 1,2-bonded butadiene units) can be measured by infrared absorption spectroscopy.

[0056] 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.

[0057] The SBR may be unmodified or modified. Examples of modified SBR include modified SBR into which functional groups similar to those in modified diene rubbers have been introduced. The SBR may also be hydrogenated.

[0058] 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. Among these, high-cis BR with a cis content of 90% by mass or more is preferred because it improves wear resistance.

[0059] The BR may be unmodified or modified. Examples of modified BR include modified BR into which functional groups similar to those of modified diene rubbers have been introduced. The BR may also be a hydrogenated product.

[0060] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0061] 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 highly purified natural rubber (UPNR). 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.

[0062] The reaction process between the nitrile oxide compound and the polymer such as the diene rubber is not particularly limited, but may be carried out in an organic solvent, in water, or without a solvent. The organic solvent is not particularly limited, but it is preferable that both the nitrile oxide compound and the polymer are easily dissolved in the organic solvent. Specific examples of the organic solvent include those mentioned above. The reaction temperature and time may be appropriately set depending on the nitrile oxide compound and the polymer.

[0063] To explain a specific example of compound synthesis, for example, a reaction product (polymer having an ionic functional group) of a nitrile oxide compound having a nitrile oxide group and an ionic functional group with a polymer having a double bond can be synthesized according to the synthesis route shown in FIG. 4.

[0064] Specifically, a nitrile oxide compound having a nitrile oxide group and an ionic functional group (compound E), BR, and SBR (diene rubber) are dissolved in a solvent, and the resulting solution is stirred under appropriate temperature conditions to cause a reaction. After the reaction is complete, the solution containing the product is precipitated in methanol and dried to obtain the target reaction product (a polymer having an ionic functional group).

[0065] Figure 5 shows the total pathway of the polymer in Figure 4. 1(A) is an example of a H-NMR (proton NMR) spectrum of SBR. 1 H-NMR spectrum, (B) is SBR with COOH (ionic functional group) 1 H-NMR spectrum, (C) is BR with COOH (ionic functional group) 1 5(B) and (C) are examples of H-NMR spectra. Figure 5(B) and (C) show that a polymer having an ionic functional group is synthesized by reacting a nitrile oxide compound (compound E) having a nitrile oxide group and an ionic functional group with BR and SBR.

[0066] <Rubber composition> The rubber composition includes, as a rubber component, the ionic functional group-containing polymer obtained by reacting a nitrile oxide compound having a nitrile oxide group and an ionic functional group with a polymer. The use of the ionic functional group-containing polymer improves tire performance such as wet grip performance.

[0067] Conventionally, when preparing a rubber composition using ionic bonds, there are limitations on the type of ion-modified rubber. For example, when SBR is used, there are limitations on the SBR skeleton. However, when the nitrile oxide compound is used, it becomes possible to impart ionic functional groups regardless of the skeleton structure, which is thought to make it easier to adjust the impartation of desired wet grip performance, such as further improving wet grip performance.

[0068] In the rubber composition, the content of the ionic functional group-containing 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. The lower limit of the content of the ionic functional group-containing rubber may be 30% by mass or more, 50% by mass or more, 60% by mass or more, or 70% by mass or more. The upper limit is not particularly limited and may be 100% by mass, or may be 90% by mass or less, 85% by mass or less, or 80% by mass or less. Within the above range, better tire performance such as wet grip performance tends to be obtained.

[0069] When the rubber composition contains the ionic functional group-containing SBR, the content of the ionic functional group-containing SBR 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. The lower limit of the content of the ionic functional group-containing rubber may be 30% by mass or more, 50% by mass or more, 60% by mass or more, or 70% by mass or more. The upper limit is not particularly limited and may be 100% by mass, or may be 90% by mass or less, 85% by mass or less, or 80% by mass or less. Within the above range, better tire performance such as wet grip performance tends to be obtained.

[0070] When the rubber composition contains the ionic functional group-containing BR, the content of the ionic functional group-containing SBR 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. The lower limit of the content of the ionic functional group-containing rubber may be 30% by mass or more, 50% by mass or more, 60% by mass or more, or 70% by mass or more. The upper limit is not particularly limited and may be 100% by mass, or may be 90% by mass or less, 85% by mass or less, or 80% by mass or less. Within the above range, better tire performance such as wet grip performance tends to be obtained.

[0071] When the rubber composition contains the ionic functional group-containing isoprene-based rubber, the content of the ionic functional group-containing SBR 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. The lower limit of the content of the ionic functional group-containing rubber may be 30% by mass or more, 50% by mass or more, 60% by mass or more, or 70% by mass or more. The upper limit is not particularly limited and may be 100% by mass, or may be 90% by mass or less, 85% by mass or less, or 80% by mass or less. Within the above range, better tire performance such as wet grip performance tends to be obtained.

[0072] From the viewpoint of obtaining better tire performance such as wet grip performance, the rubber composition desirably contains at least one selected from the group consisting of alkali metal salt and alkaline earth metal salt fillers.

[0073] Examples of alkali metal salts and alkaline earth metal salts include at least one alkali metal salt or alkaline earth metal salt selected from the group consisting of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, beryllium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, lithium acetate, sodium acetate, potassium acetate, rubidium acetate, cesium acetate, beryllium acetate, magnesium acetate, calcium acetate, strontium acetate, barium acetate, lithium phenoxide, sodium phenoxide, potassium phenoxide, rubidium phenoxide, cesium phenoxide, beryllium diphenoxide, magnesium diphenoxide, calcium diphenoxide, strontium diphenoxide, and barium diphenoxide. These alkali metal salts or alkaline earth metal salts may be used alone or in combination of two or more.

[0074] Among these, from the viewpoint of obtaining the effect more suitably, it is more preferable to contain at least one selected from the group consisting of potassium acetate, calcium acetate, sodium acetate, and magnesium acetate, it is even more preferable to contain at least one selected from the group consisting of potassium acetate, calcium acetate, and sodium acetate, and it is particularly preferable to contain potassium acetate and / or calcium acetate.

[0075] In the rubber composition, the content of the alkali metal salt or alkaline earth metal salt (total amount of the alkali metal salt or alkaline earth metal salt) per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 2.0 parts by mass or more, even more preferably 5.0 parts by mass or more, still more preferably 7.0 parts by mass or more, particularly preferably 7.2 parts by mass or more, and is preferably 20.0 parts by mass or less, more preferably 17.0 parts by mass or less, even more preferably 12.0 parts by mass or less, particularly preferably 10.0 parts by mass or less. Within the above ranges, the effects tend to be more favorably obtained.

[0076] The apparent specific gravity of the alkali metal salt or alkaline earth metal salt is preferably less than 0.4 g / ml, more preferably 0.3 g / ml or less, even more preferably 0.25 g / ml or less, and is preferably 0.05 g / ml or more, more preferably 0.15 g / ml or more. Within the above ranges, better effects tend to be obtained. The apparent specific gravity of the alkali metal salt or alkaline earth metal salt is a value obtained by measuring 30 ml of the apparent volume into a 50 ml measuring cylinder and calculating from the mass.

[0077] The d50 of the alkali metal salt or alkaline earth metal salt is preferably less than 10 μm, more preferably 4.5 μm or less, even more preferably 1.5 μm or less, particularly preferably less than 0.75 μm, and is preferably 0.05 μm or more, more preferably 0.45 μm or more. Within the above ranges, better effects tend to be obtained. The d50 of the alkali metal salt or alkaline earth metal salt is the particle size at 50% of the integrated value in a mass-based particle size distribution curve obtained by a laser diffraction scattering method.

[0078] The nitrogen adsorption specific surface area (N2SA) of the alkali metal salt or alkaline earth metal salt is preferably 100 m 2 / g or more, more preferably 115m 2 / g or more, and preferably 250m 2 / g or less, more preferably 225m 2 / g or less, more preferably 200m 2 Within the above range, there is a tendency for the effect to be better obtained. The N2SA of the alkali metal salt or alkaline earth metal salt is a value measured by the BET method in accordance with JIS Z8830:2013.

[0079] Commercially available products of the alkali metal salts or alkaline earth metal salts include those from Kyowa Chemical Industry Co., Ltd., Fujifilm Wako Pure Chemical Industries Co., Ltd., Kishida Chemical Co., Ltd., Kyowa Chemical Industry Co., Ltd., Tateho Chemical Industry Co., Ltd., JHE Co., Ltd., Nippon Chemical Industry Co., Ltd., Ako Kasei Co., Ltd., etc.

[0080] The rubber composition preferably contains a filler. Examples of fillers that can be used include inorganic fillers such as silica, carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica; and poorly dispersible fillers, all of which are well known in the rubber field. Among these, silica and carbon black are preferred, and silica is more preferred.

[0081] In the rubber composition, the total amount of filler 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, and particularly preferably 25 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 200 parts by mass or less, more preferably 180 parts by mass or less, and even more preferably 160 parts by mass or less. Within the above range, better tire performance such as wet grip performance tends to be obtained.

[0082] Usable silica includes, for example, dry-process silica (anhydrous silica) and wet-process silica (hydrated silica). Among them, wet-process silica is preferred because it has a large number of silanol groups. Examples of silica that can be used include products from Degussa, Rhodia, Tosoh Silica, Solvay Japan, and Tokuyama.

[0083] 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 2Within 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.

[0084] In the rubber composition, the content of 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, and particularly preferably 25 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 200 parts by mass or less, more preferably 180 parts by mass or less, and even more preferably 160 parts by mass or less. Within the above range, better tire performance such as wet grip performance tends to be obtained.

[0085] When silica is contained, a silane coupling agent may be blended together with the silica. The silane coupling agent that can be used is not particularly limited and may be any silane coupling agent that has conventionally been used in combination with silica in the rubber industry, and examples thereof include 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-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-triethoxysilylpropyl Examples of such compounds include sulfide-based compounds such as trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; 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 include those from Degussa, Momentive, Shin-Etsu Silicone 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. Of these, sulfide-based and mercapto-based products are preferred.

[0086] In the rubber composition, the content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, relative to 100 parts by mass of silica, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less.

[0087] Usable carbon blacks include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. These may be used alone or in combination of two or more. Commercially available carbon blacks include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., and Columbia Carbon Co., Ltd.

[0088] The nitrogen adsorption specific surface area (N2SA) of the carbon black 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 nitrogen adsorption specific surface area of carbon black is determined in accordance with JIS K6217-2:2001.

[0089] In the rubber composition, the carbon black content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 200 parts by mass or less, more preferably 180 parts by mass or less, and even more preferably 160 parts by mass or less. Within the above range, better tire performance such as wet grip performance tends to be obtained.

[0090] The rubber composition may contain a plasticizer. Here, the plasticizer is a material that imparts plasticity to the rubber component, and examples thereof include a liquid plasticizer (a plasticizer that is in a liquid state at room temperature (25°C)) and a resin (a resin that is in a solid state at room temperature (25°C)).

[0091] In the rubber composition, the content of plasticizers (total amount of plasticizers) is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 90 parts by mass or less. Within the above range, better tire performance such as wet grip performance tends to be obtained.

[0092] Liquid plasticizers (plasticizers that are liquid at room temperature (25°C)) that can be used in the rubber composition are not particularly limited, and examples include oils, liquid polymers (liquid resins, liquid diene-based polymers, liquid farnesene-based polymers, etc.), etc. These may be used alone or in combination of two or more.

[0093] In the rubber composition, the total amount of liquid plasticizers is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 90 parts by mass or less. Within the above range, tire performance such as wet grip performance tends to be better. The content of liquid plasticizer also includes the amount of oil contained in the oil-extended rubber.

[0094] Examples of oils include process oils, vegetable oils, and mixtures thereof. Examples of process oils that can be used include paraffin-based process oils, aromatic process oils, and naphthenic process oils. Examples of vegetable oils that can be used include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Commercially available products include those from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Corporation, Oriso Co., Ltd., H&R Corporation, Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and Nisshin Oillio Group, Ltd. Among these, process oils (paraffin-based process oils, aromatic process oils, naphthenic process oils, etc.) and vegetable oils are preferred.

[0095] Examples of liquid resins include terpene resins (including terpene phenol resins and aromatic modified terpene resins), rosin resins, styrene resins, C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene (DCPD) resins, coumarone-indene resins (including coumarone and indene simple resins), phenol resins, olefin resins, polyurethane resins, acrylic resins, etc. Hydrogenated products of these resins can also be used.

[0096] Examples of liquid diene polymers include liquid styrene butadiene copolymers (liquid SBR), liquid butadiene polymers (liquid BR), liquid isoprene polymers (liquid IR), liquid styrene isoprene copolymers (liquid SIR), liquid styrene butadiene styrene block copolymers (liquid SBS block polymers), liquid styrene isoprene styrene block copolymers (liquid SIS block polymers), liquid farnesene polymers, and liquid farnesene butadiene copolymers, all of which are liquid at 25°C. The terminals or main chains of these polymers may be modified with polar groups. Hydrogenated versions of these polymers can also be used.

[0097] Examples of the resins (resins that are solid at room temperature (25°C)) that can be used in the rubber composition include aromatic vinyl polymers, coumarone-indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, and acrylic resins that are solid at room temperature (25°C). The resins may also be hydrogenated. These may be used alone or in combination of two or more. Of these, aromatic vinyl polymers, petroleum resins, and terpene resins are preferred.

[0098] In the rubber composition, the content of the resin is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 90 parts by mass or less. Within the above range, better tire performance such as wet grip performance tends to be obtained.

[0099] The softening point of the resin is preferably 50°C or higher, more preferably 55°C or higher, and even more preferably 60°C or higher. The upper limit is preferably 160°C or lower, more preferably 150°C or lower, and even more preferably 145°C or lower. Within the above range, tire performance such as wet grip performance tends to be better. 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.

[0100] 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.

[0101] 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.

[0102] The coumarone resin is a resin containing coumarone as a main monomer component constituting the skeleton (main chain) of the resin.

[0103] The indene resin is a resin containing indene as a main monomer component constituting the skeleton (main chain) of the resin.

[0104] 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.

[0105] Examples of the rosin resin include rosin-based resins such as natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

[0106] Examples of the petroleum resin include C5 resin, C9 resin, C5 / C9 resin, dicyclopentadiene (DCPD) resin, and hydrogenated versions of these resins. Of these, DCPD resin and hydrogenated DCPD resin are preferred.

[0107] 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 that can be used 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, examples of phenolic compounds include phenol and bisphenol A, and examples of aromatic compounds include styrene compounds (styrene, α-methylstyrene, etc.).

[0108] 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.

[0109] Examples of plasticizers 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, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0110] The rubber composition preferably contains an antioxidant from the viewpoint of crack resistance, ozone resistance, and the like.

[0111] The antioxidant is not particularly limited, but 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, N,N'-di-2-naphthyl-p-phenylenediamine, and the like. Examples of suitable antioxidants include p-phenylenediamine antioxidants such as amines; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; 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 antioxidants and quinoline antioxidants are preferred, with polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline being more preferred. Commercially available products include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., and Flexis.

[0112] In the rubber composition, the content of the antioxidant is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less.

[0113] The rubber composition may contain stearic acid. The content of stearic acid in the rubber composition is preferably 0.5 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0114] 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.

[0115] The rubber composition may contain zinc oxide. The content of zinc oxide in the rubber composition is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0116] 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.

[0117] The rubber composition may contain wax. The content of the wax in the rubber composition is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0118] The wax is not particularly limited, and examples thereof include petroleum waxes, natural waxes, etc. Synthetic waxes obtained by refining or chemically treating multiple waxes can also be used. These waxes may be used alone or in combination of two or more types.

[0119] Examples of petroleum-based waxes include paraffin wax and microcrystalline wax. Natural waxes are not particularly limited as long as they are derived from non-petroleum resources, and include, for example, plant-based waxes such as candelilla wax, carnauba wax, Japan wax, rice wax, and jojoba wax; animal-based waxes such as beeswax, lanolin, and spermaceti; mineral-based waxes such as ozokerite, ceresin, and petrolactam; and refined products thereof. Commercially available products include those from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd.

[0120] The rubber composition may contain sulfur in order to form appropriate crosslinked chains in polymer chains and to provide a good balance of the above performances.

[0121] In the rubber composition, the sulfur content is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and even more preferably 0.7 part by mass or more, per 100 parts by mass of the rubber component, and is preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less.

[0122] 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.

[0123] The rubber composition may contain a vulcanization accelerator. In the rubber composition, the content of the vulcanization accelerator is usually 0.3 to 10 parts by mass, and preferably 0.5 to 7 parts by mass, per 100 parts by mass of the rubber component.

[0124] The type of vulcanization accelerator is not particularly limited, and commonly used ones can be used. Examples of the vulcanization accelerator include thiazole-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 vulcanization accelerators and guanidine vulcanization accelerators are preferred.

[0125] In addition to the above components, the rubber composition may contain additives such as a mold release agent and a pigment, which are commonly used in accordance with the field of application.

[0126] The rubber composition can be produced by a known method. For example, the rubber composition can be produced by kneading the components using a rubber kneading device such as an open roll or a Banbury mixer, and optionally crosslinking the components. The kneading conditions are as follows: the kneading temperature is usually 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30 seconds to 30 minutes, preferably 1 minute to 30 minutes.

[0127] 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.

[0128] From the viewpoint of obtaining better tire performance such as wet grip performance, it is desirable that the rubber composition satisfy the following formula (1): (1) E* when wet / E* when dry ≦ 0.95 (In the formula, E* is the complex modulus (MPa) 30 minutes after the start of measurement, measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10 Hz, an extension mode, and a measurement time of 30 minutes.) The ratio E* when wet / E* when dry is preferably 0.91 or less, more preferably 0.88 or less, even more preferably 0.86 or less, particularly preferably 0.84 or less, and most preferably 0.81 or less. There are no particular restrictions on the lower limit of E* when wet / E* when dry, but it is preferably 0.10 or more, more preferably 0.30 or more, even more preferably 0.50 or more, and particularly preferably 0.60 or more. Within the above range, the effects can be suitably obtained.

[0129] The rubber composition has an E* value in a dry state of preferably 3.0 MPa or more, more preferably 52.0 MPa or more, even more preferably 58.0 MPa or more, and particularly preferably 66.0 MPa or more. There is no particular upper limit to the E* value in a dry state, but it is preferably 200.0 MPa or less, more preferably 176.0 MPa or less, even more preferably 150.0 MPa or less, and particularly preferably 100.0 MPa or less. When it is within the above range, the effects can be suitably obtained.

[0130] The rubber composition has an E* value when wet with water of preferably 3.0 MPa or more, more preferably 45.0 MPa or more, even more preferably 55.0 MPa or more, and particularly preferably 60.0 MPa or more. There is no particular upper limit to E* value when dry, but it is preferably 180.0 MPa or less, more preferably 150.0 MPa or less, even more preferably 110.0 MPa or less, and particularly preferably 90.0 MPa or less. Within the above range, the effects can be suitably obtained.

[0131] In this specification, the complex modulus (E*) of a rubber composition refers to the E* of the rubber composition after vulcanization. E* is a value obtained by conducting a viscoelasticity test on the rubber composition after vulcanization.

[0132] The rubber composition satisfies the formula (1) and, for example, the complex modulus (E*) changes reversibly with water. In this specification, "the complex modulus (E*) changes reversibly with water" means that the E* of the rubber composition (after vulcanization) reversibly increases or decreases with the presence of water. Note that, for example, when changing from dry to wet to dry, it is sufficient that E* changes reversibly, and the E* does not have to be the same between the previous drying and the subsequent drying, or the E* may be the same between the previous drying and the subsequent drying.

[0133] In this specification, E* in a dry state means the E* of a rubber composition in a dry state, and specifically means the E* of a rubber composition dried by the method described in the examples. In this specification, E* when wet with water means E* of a rubber composition in a state wet with water, and specifically means E* of a rubber composition wet with water by the method described in the examples.

[0134] In this specification, E* of a rubber composition is E* measured 30 minutes after the start of measurement under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10 Hz, an extension mode, and a measurement time of 30 minutes.

[0135] The reversible change in E* of the rubber composition due to water, represented by the formula (1), can be achieved, for example, by using the ionic functional group-containing polymer and, if necessary, the alkali metal salt or alkaline earth metal salt.

[0136] The dry E* can be adjusted by the type and amount of chemicals (especially rubber components, fillers, softeners such as oils) compounded into the rubber composition. For example, the dry E* tends to increase by reducing the amount of softener or increasing the amount of filler.

[0137] Furthermore, the E* value upon drying can be adjusted, for example, by adjusting the ionic functional group content of the ionic functional group-containing polymer or the content of the alkali metal salt or alkaline earth metal salt (in other words, the metal content derived from the alkali metal salt or alkaline earth metal salt). Specifically, increasing the ionic functional group content of the ionic functional group-containing polymer or the content of the alkali metal salt or alkaline earth metal salt tends to increase the E* value upon drying.

[0138] The E* value when wet with water can be lowered compared to the dry state by, for example, preparing a rubber composition in which the ionic functional group-containing polymer and the alkali metal salt or alkaline earth metal salt are partially or entirely crosslinked by ionic bonds, thereby enabling adjustment of the E* values when wet and dry. Specifically, the combined use of the ionic functional group-containing polymer and the alkali metal salt or alkaline earth metal salt results in a rubber composition crosslinked by ionic bonds, allowing the E* value when wet with water to be lowered compared to the dry state. The E* value when wet with water can also be adjusted by the type and amount of chemicals blended into the rubber composition. For example, a similar tendency can be obtained for the E* value when wet by using a method similar to that for adjusting the E* value when dry.

[0139] Specifically, the reversible change in E* of the rubber composition due to water, as represented by the formula (1), can be realized by adjusting the dry E* to fall within a desired range and then using the ionic functional group-containing polymer and, if necessary, the alkali metal salt or alkaline earth metal salt.

[0140] 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.

[0141] <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, tires for large passenger cars, tires for large SUVs, 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.

[0142] A tire is manufactured using the rubber composition by a conventional method. 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]

[0143] The present disclosure will be specifically described based on examples, but the present disclosure is not limited to these examples.

[0144] <Synthesis of nitrile oxide compounds 1> Compound E (a nitrile oxide compound having a nitrile oxide group and an ionic functional group) was synthesized according to the synthetic route shown in FIG.

[0145] (Compound A → Compound B) First, a stirrer, 2-hydroxy-1-naphthaldehyde (compound A), K2CO3, DMF (N,N-dimethylformamide), and ethyl 6-bromohexanoate were added to a three-neck flask and stirred to dissolve. The mixture was then heated in an oil bath at 100°C for 3 hours. The mixture was then cooled to room temperature and separated using ethyl acetate and water. The ethyl acetate layer was dried over MgSO4 and evaporated. The residue was recrystallized in hexane to obtain compound B.

[0146] (Compound B → Compound C) Compound B and NaOH were dissolved in a mixed solvent of THF: iPrOH: HO = (4:2:1) and reacted overnight at room temperature. After the reaction was complete, the mixture was neutralized with hydrochloric acid and evaporated. The residue was diluted with water and poured into a separatory funnel with ethyl acetate to separate the layers. The ethyl acetate layer was dried over MgSO4, evaporated to dryness, and then vacuum dried to obtain compound C.

[0147] (Compound C → Compound D) A stir bar, compound C, and ethanol were added to a 500 ml beaker and stirred to dissolve. An aqueous solution of CH3COONa·3H2O and NH2OH·HCl was added to the compound C solution and allowed to react at room temperature for 4 hours, resulting in a precipitate. The mixture was filtered, and the precipitate was collected and dried in vacuo to obtain compound D.

[0148] (Compound D → Compound E) A stirrer, compound D, and 2-propanol were added to a three-neck flask, which was then placed in an ice bath and stirred to disperse. NaClO solution was added to the flask using a dropping funnel at 0-5°C, and the mixture was allowed to react. After the reaction was complete, the pH was adjusted to approximately 5 with HCl, and the mixture was separated with CHCl3. The CHCl3 layer was dried over MgSO4, evaporated to dryness, and then recrystallized from ethanol / water to obtain the desired compound E (a nitrile oxide compound having a nitrile oxide group and an ionic functional group).

[0149] synthetic 1The H-NMR spectrum (Fig. 2) and IR spectrum (Fig. 3) revealed that compound E (a nitrile oxide compound having a nitrile oxide group and an ionic functional group) had been synthesized.

[0150] <Synthesis of nitrile oxide compounds 2> Compound H (a nitrile oxide compound having a nitrile oxide group and an ionic functional group) was synthesized according to the synthetic route shown in FIG.

[0151] (Compound A → Compound F) First, a stirrer, 2-hydroxy-1-naphthaldehyde (compound A), K2CO3, DMF (N,N-dimethylformamide), and 6-chlorohexanol were added to a three-neck flask and stirred to dissolve. The mixture was then heated in an oil bath and reacted at 100°C for 5 hours. The mixture was then cooled to room temperature and separated using ethyl acetate and water. The ethyl acetate layer was dried over MgSO4 and evaporated to obtain compound F.

[0152] (Compound F → Compound G) A stir bar, compound F, and ethanol were added to a 500 ml beaker and stirred to dissolve. An aqueous solution of CH3COONa·3H2O and NH2OH·HCl was added to the compound F solution and allowed to react at room temperature for 4 hours, resulting in a precipitate. The mixture was filtered, and the precipitate was collected and dried in vacuo to obtain compound G.

[0153] (Compound G → Compound H) A stirrer, compound G, and 2-propanol were added to a three-neck flask, which was then placed in an ice bath and stirred to disperse. NaClO solution was added to the flask using a dropping funnel at 0-5°C, and the reaction was allowed to proceed. After the reaction was complete, the pH was adjusted to approximately 5 with HCl, and the mixture was precipitated with water and filtered to obtain the target compound H (a nitrile oxide compound having a nitrile oxide group and an ionic functional group) as a solid.

[0154] (Compound H → Compound I) A stirrer, compound H, and dry THF were added to a three-neck flask, which was then placed in an ice bath and stirred to dissolve. A dry THF solution of 2-Bromoisobutyrylbromide was added to the flask using a dropping funnel at 0-5°C, and the reaction was allowed to proceed. After the reaction was complete, the reaction mixture was filtered, and the filtrate was separated into water and ethyl acetate. The organic layer was dried over MgSO4 and evaporated to obtain compound I.

[0155] synthetic 1 From the H-NMR spectrum and IR spectrum, it was found that compound H (a nitrile oxide compound having a nitrile oxide group and an ionic functional group) was synthesized.

[0156] <Synthesis of nitrile oxide compounds 3> Compound e (a nitrile oxide compound having a nitrile oxide group and an ionic functional group) was synthesized according to the synthetic route shown in FIG.

[0157] (Compound a→Compound b) A stirrer, compound a, 4-(bromomethyl) benzoate, K2CO3, and 18-crown-6 were added to a three-neck flask and stirred to dissolve. The mixture was then heated in an oil bath and reacted overnight at 40°C. The reaction mixture was evaporated, and the solid was separated using dichloromethane and 3% aqueous hydrochloric acid. The dichloromethane layer was dried over MgSO4 and evaporated. The solid was recrystallized from hexane / ethyl acetate (7 / 1 v / v) to obtain compound b.

[0158] (Compound b→Compound c) Compound b and LiOH were dissolved in a mixed solvent of THF: iPrOH: HO = (4:2:1) and reacted overnight at room temperature. After the reaction was completed, the pH was adjusted to 5 using hydrochloric acid and evaporated. The residue was separated with dichloromethane / water, and the organic layer was dried over MgSO and evaporated to obtain compound c.

[0159] (Compound c→Compound d) A stir bar, compound c, and ethanol were added to a 500 ml beaker and stirred to dissolve. An aqueous solution of CH3COONa·3H2O and NH2OH·HCl was added to the compound c solution and allowed to react at room temperature for 4 hours, resulting in a precipitate. The mixture was filtered, and the precipitate was collected and dried in vacuo to obtain compound d.

[0160] (Compound d→Compound e) A stirrer, compound d, and DMF were added to a three-neck flask, which was then placed in an ice bath and stirred to dissolve. A DMF solution of NBS was added to the flask using a dropping funnel at 0-5°C, and the reaction was allowed to proceed. After 10 minutes, a DMF solution of TEA was added to the flask using a dropping funnel, and the reaction was allowed to proceed. After the reaction was complete, the mixture was separated with water and ethyl acetate, and the organic layer was dried over MgSO4 and evaporated to obtain compound e (a nitrile oxide compound having a nitrile oxide group and an ionic functional group).

[0161] synthetic 1 From the H-NMR spectrum and IR spectrum, it was found that compound e (a nitrile oxide compound having a nitrile oxide group and an ionic functional group) was synthesized.

[0162] <Synthesis of polymers containing ionic functional groups> Compound E (a nitrile oxide compound having a nitrile oxide group and an ionic functional group) obtained in the synthesis of the nitrile oxide compound and a polymer were dissolved in a solvent to form a solution, which was then stirred and reacted according to the recipe and conditions shown in Table 1. After the reaction was completed, the solution containing the product was precipitated using methanol and dried to obtain diene rubbers having carboxylic acid groups (ionic functional group-containing polymers (BR1-1 to BR1-5, ESBR-1 to ESBR-9, SSBR1-1 to SSBR1-3), (BR2-1 to BR2-2, SSBR2-1 to SSBR2-2, SSBR1-4 to SSBR1-5)).

[0163] The double bond modification rate and nitrile oxide compound reaction rate in Table 1 are defined below and were measured by the following method. (Double bond modification rate (%)) = [amount of carbon-carbon double bonds reacted with nitrile oxide compound / (amount of remaining carbon-carbon double bonds + amount of carbon-carbon double bonds reacted with nitrile oxide compound)] × 100 (nitrile oxide compound reaction rate (%)) = (amount of nitrile oxide compound reacted with double bonds) / (amount of nitrile oxide compound charged) × 100

[0164] (1) Double bond modification rate The ratio of nitrile oxide compounds added to carbon-carbon double bonds in the polymer was measured by IR. 1 H-NMR measurement and 13 Calculated by C-NMR measurement.

[0165] (2) Reaction rate of nitrile oxide compounds IR measurement, 1 H-NMR measurement and 13 It was determined by C-NMR measurement.

[0166] (Measurement of glass transition temperature (Tg)) The glass transition temperature (Tg) of the prepared ionic functional group-containing polymer was determined as the glass transition onset temperature by measuring the temperature at a heating rate of 10°C / min using a differential scanning calorimeter (Q200) manufactured by TA Instruments Japan, in accordance with JIS K 7121.

[0167] [Table 1]

[0168] The following materials were used for BR1, ESBR, SSBR1, BR2, and SSBR2 in Table 1. BR1: BR150B (cis content 96% by mass) manufactured by Ube Industries, Ltd. ESBR: Nipol 1502 (E-SBR, styrene content 23.5% by mass, vinyl content 18% by mass) manufactured by ZEON Corporation SSBR1: HPR850 (S-SBR) manufactured by JSR Corporation BR2: BR730 manufactured by JSR Corporation (BR synthesized using a Nd-based catalyst, cis content 96% by mass) SSBR2: HPR840 (S-SBR) manufactured by JSR Corporation

[0169] synthetic 1 The H-NMR spectrum (Figure 5) revealed that a diene rubber with carboxylic acid groups (a polymer containing ionic functional groups) had been synthesized.

[0170] From the Tg of BR2-1 to BR2-2, SSBR2-1 to SSBR2-2, and SSBR1-4 to SSBR1-5 (ionic functional group-containing polymers) in Table 1, it was found that the ionic functional group-containing polymers have higher Tg than the corresponding polymers.

[0171] As described above, it was found that it is possible to synthesize a nitrile oxide compound having a nitrile oxide group and an ionic functional group, and that it is also possible to synthesize a polymer containing an ionic functional group by reacting the nitrile oxide compound with BR, ESBR, or SSBR.

[0172] The nitrile oxide group and the nitrile oxide group in a nitrile oxide compound having an ionic functional group are highly reactive and can react with any polymer. Therefore, it is considered that an ionic functional group can be introduced into a polymer by reacting the nitrile oxide group in a nitrile oxide compound with any polymer (such as isoprene-based rubber or other polymers having double bonds), and it is considered that it is possible to provide ionic functional group-containing polymers having various ionic functional groups.

[0173] <Preparation of Rubber Composition> The various chemicals used are summarized below. SSBR1: HPR850 (S-SBR) manufactured by JSR Corporation SSBR1-4: SBR containing ionic functional groups prepared according to Table 1 SSBR1-5: SBR containing ionic functional groups prepared according to Table 1 SSBR2: HPR840 (S-SBR) manufactured by JSR Corporation SSBR2-1: SBR containing ionic functional groups prepared according to Table 1 SSBR2-2: SBR containing ionic functional groups prepared according to Table 1 BR2: BR730 manufactured by JSR Corporation (BR synthesized using a Nd-based catalyst, cis content 96% by mass) BR2-1: BR containing ionic functional groups prepared according to Table 1 BR2-2: BR containing ionic functional groups prepared according to Table 1 Potassium acetate: Potassium acetate manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Silica: Ultrasil VN3 (N2SA: 175 ml) manufactured by Evonik Degussa 2 / g) Silane coupling agent: Si266 manufactured by Evonik Degussa Stearic acid: NOF Corporation's "Tsubaki" stearic acid Oil: Diana Process NH-70S manufactured by Idemitsu Kosan Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator NS: Noccela NS (N-tert-butyl-2-benzothiazylsulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator DPG: Noccela D (1,3-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0174] (Production of rubber composition) According to the compounding recipes shown in Tables 2 to 5, chemicals other than sulfur and vulcanization accelerator were kneaded for 4 minutes at 160°C using a 16L Banbury mixer manufactured by Kobe Steel, Ltd. To the kneaded mixture, sulfur and vulcanization accelerator were added, and the mixture was kneaded for 4 minutes at 80°C using an open roll to obtain an unvulcanized rubber composition. The resulting unvulcanized rubber composition was press-vulcanized at 170°C for 12 minutes to obtain a vulcanized rubber composition.

[0175] The vulcanized rubber compositions thus obtained were subjected to the following physical property measurements and evaluations. The results are shown in the tables. The reference comparative examples were as follows: Table 2: Comparative Example 1-1 Table 3: Comparative Example 2-1 Table 4: Comparative Example 3-1 Table 5: Comparative Example 4-1

[0176] <Viscoelasticity test> A viscoelasticity measurement sample measuring 40 mm in length, 3 mm in width, and 0.5 mm in thickness was taken from each vulcanized rubber composition, and the E* of the vulcanized rubber composition was measured using an RSA series manufactured by TA Instruments under the following conditions: temperature 30°C, initial strain 10%, dynamic strain 1%, frequency 10 Hz, extension mode, and measurement time 30 minutes, with the measured value obtained 30 minutes after the start of measurement.

[0177] <E* when dry> The viscoelasticity measurement sample (length 40 mm × width 3 mm × thickness 0.5 mm) was dried at room temperature and normal pressure until it reached a constant weight. The complex modulus E* of the resulting dried vulcanized rubber composition (rubber piece) was measured using the viscoelasticity test method described above, and this was taken as E* in the dry state.

[0178] <E* when wet> The viscoelasticity was measured in water using the RSA immersion measurement jig according to the viscoelasticity test method described above, and the E* value was determined when the sample was wet with water. The water temperature was set at 30°C.

[0179] <Decrease in E* when wet> The reciprocal of the "E* when wet / E* when dry" of each vulcanized rubber composition was expressed as an index, with the "E* when wet / E* when dry" of the vulcanized rubber composition of the reference comparative example being set at 100. The larger the index, the better the decrease in E* when wet, indicating better wet performance such as wet grip performance.

[0180] [Table 2]

[0181] [Table 3]

[0182] [Table 4]

[0183] [Table 5]

[0184] As can be seen from Tables 2 to 5, in rubber compositions containing ionic functional group-containing SBRs (SSBR1-4, SSBR1-5, SSBR2-1, SSBR2-2, BR2-1, BR2-2), the E* when wet with water was lower than the E* when dry, compared to the rubber compositions containing the corresponding polymers (SSBR1, SSBR2, BR2). Thus, by modifying each polymer to form an ionic functional group-containing polymer, a tendency for softening with water was observed.

[0185] Furthermore, the IR spectra of Example 1-1, which used SSBR1-4 (SBR containing an ionic functional group), and Comparative Example 1-1, which used the corresponding SSBR1, and their difference spectrum (FIG. 8) revealed that a COOH-Zn bond was formed.

[0186] From the above, it was thought that when various ionic functional group-containing polymers having ionic bond points (sites where ionic bonds are formed) are used in a rubber composition for tires, upon contact with a wet road surface, the ionic bond points become dissociated, the crosslinking loosens, and the elastic modulus decreases, and when driving on a wet road surface, the contact area with the road surface increases, friction increases, loss improves, and wet grip performance is improved.

[0187] The present disclosure (1) is a nitrile oxide compound having a nitrile oxide group and an ionic functional group.

[0188] The present disclosure (2) is the nitrile oxide compound according to the present disclosure (1), wherein the ionic functional group is at least one selected from the group consisting of an amino group and a carboxylic acid group.

[0189] The present disclosure (3) is a nitrile oxide compound according to the present disclosure (1) or (2), which is a compound containing a cyclic structure.

[0190] The present disclosure (4) is a nitrile oxide compound according to the present disclosure (1) or (2), which is a compound having an aromatic ring.

[0191] The present disclosure (5) is a nitrile oxide compound according to the present disclosure (1) or (2), which is a compound having a naphthalene ring.

[0192] The present disclosure (6) is an ionic functional group-containing polymer obtained by reacting a polymer with a nitrile oxide compound having a nitrile oxide group and an ionic functional group according to any one of the present disclosures (1) to (5).

[0193] The present disclosure (7) is the ionic functional group-containing polymer according to the present disclosure (6), wherein the polymer is at least one selected from the group consisting of styrene-butadiene rubber, butadiene rubber, and isoprene-based rubber.

[0194] The present disclosure (8) is a rubber composition containing the ionic functional group-containing polymer according to the present disclosure (6) or (7).

[0195] The present disclosure (9) is the ionic functional group-containing polymer according to the present disclosure (6), wherein the ionic functional group-containing polymer contains at least one selected from the group consisting of ionic functional group-containing styrene-butadiene rubber and ionic functional group-containing styrene-butadiene rubber.

[0196] The present disclosure (10) is the rubber composition according to the present disclosure (8) or (9), which contains at least one selected from the group consisting of silica and carbon black.

[0197] The present disclosure (11) is a rubber composition according to any one of the present disclosures (8) to (10), which satisfies the following formula (1): (1) E* when wet / E* when dry ≦ 0.95 (In the formula, E* is the complex modulus (MPa) 30 minutes after the start of measurement, measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10 Hz, an extension mode, and a measurement time of 30 minutes.)

[0198] The present disclosure (12) is a tire using the rubber composition according to any one of the present disclosures (8) to (11).

Claims

1. It has a nitrile oxide group and an ionic functional group, It has a naphthalene ring, A tire using a rubber composition containing an ionic functional group-containing polymer obtained by reacting a polymer with a nitrile oxide compound represented by the following formula, in which the ionic functional group is a carboxylic acid group: 【Chemical 1】 (In the formula, A represents a monovalent ionic functional group, and Y represents a substituted or unsubstituted divalent hydrocarbon group which may contain a heteroatom.)

2. It has a nitrile oxide group and an ionic functional group, It has a naphthalene ring, A rubber composition comprising an ionic functional group-containing polymer obtained by reacting a polymer with a nitrile oxide compound represented by the following formula, in which the ionic functional group is a carboxylic acid group, and sulfur. 【Chemistry 2】 (In the formula, A represents a monovalent ionic functional group, and Y represents a substituted or unsubstituted divalent hydrocarbon group which may contain a heteroatom.)

3. It has a nitrile oxide group and an ionic functional group, It has a naphthalene ring, A rubber composition comprising an ionic functional group-containing polymer obtained by reacting a polymer with a nitrile oxide compound represented by the following formula, in which the ionic functional group is a carboxylic acid, and at least one selected from the group consisting of silica and carbon black: 【Chemistry 3】 (In the formula, A represents a monovalent ionic functional group, and Y represents a substituted or unsubstituted divalent hydrocarbon group which may contain a heteroatom.)

4. 4. The tire according to claim 1, or the rubber composition according to claim 2 or 3, wherein the polymer is at least one selected from the group consisting of styrene-butadiene rubber, butadiene rubber, and isoprene-based rubber.

5. The tire according to claim 1, or the rubber composition according to any one of claims 2 to 4, wherein the ionic functional group-containing polymer includes at least one selected from the group consisting of an ionic functional group-containing styrene-butadiene rubber and an ionic functional group-containing butadiene rubber.

6. The tire according to claim 1, or the rubber composition according to any one of claims 2, 4 and 5, further comprising at least one selected from the group consisting of silica and carbon black.

7. The tire according to claim 1, or the rubber composition according to any one of claims 2 to 6, which satisfies the following formula (1): (1) E* when wet / E* when dry ≦ 0.95 (In the formula, E* is the complex modulus (MPa) 30 minutes after the start of measurement, measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10 Hz, an extension mode, and a measurement time of 30 minutes.)

8. A tire using the rubber composition according to any one of claims 2 to 7.

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