Rubber composition and heat generation reduction agent for rubber

Abstract

The purpose of the present invention is to provide a rubber composition having, in a vulcanized rubber, superior low heat generation properties (low fuel consumption properties). The rubber composition comprises a rubber component, and a compound represented by formula (1) and / or a salt thereof. Also provided is a heat generation reduction agent for rubber.

Description

Rubber composition and low heat generating agent for rubber

[0001] The present invention relates to a rubber composition and a heat-reducing agent for rubber.

[0002] Patent Document 1 discloses a rubber composition based on a diene elastomer, a reinforcing filler, a chemical crosslinking agent, and a modifier.

[0003] US Patent No. 5,949,999 discloses a heavy vehicle tire comprising a tread made of a crosslinked rubber composition, said composition being based on an elastomeric matrix, a reinforcing filler, a reinforcing inorganic filler / functionalized diene elastomer binder, a chemical crosslinker, and a modifier.

[0004] US Pat. No. 5,699,499 discloses a process for producing diene elastomers modified with 1,3-dipolar compounds.

[0005] Patent Document 4 discloses a nitrile oxide compound having a nitrile oxide group and an ionic functional group.

[0006] US Pat. No. 5,629,499 discloses a rubber composition based on a diene elastomer, a 1,3-dipolar compound, and a reinforcing filler.

[0007] Patent Publication No. 2013-531726, Patent Publication No. 2016-506429, U.S. Publication No. US2019 / 0315888A1, International Publication No. WO2022 / 244317A1, U.S. Publication No. US2018 / 0346691A1

[0008] An object of the present invention is to provide a rubber composition which, when vulcanized, has excellent low heat buildup (fuel economy).

[0009] The present inventors have conducted extensive research to solve the above problems.

[0010] The present inventors have found that a compound (crosslinking agent) having a functional group having a specific nitrile oxide group, a specific spacer moiety, and a triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl group, which may have a substituent at a substitutable position, can impart superior low heat buildup to vulcanized rubber.

[0011] The present inventors have further investigated based on the above findings and have completed the present invention. The present invention encompasses the rubber composition, tire, and low heat buildup agent for rubber described below.

[0012] Item 1. A rubber composition comprising a rubber component and a compound represented by the following formula (1) and / or a salt thereof: [In formula (1), X represents a functional group having a nitrile oxide group. In formula (1), A represents a spacer moiety. In formula (1), Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position.]

[0013] Item 2. The rubber composition according to Item 1, wherein in formula (1), Y represents at least one functional group selected from the group consisting of the following formulas (4a), (4b), (4c), and (4d): [In formulas (4a), (4b), (4c), and (4d), y1 and y2 may be the same or different and each represent a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S).]

[0014] Item 3. In the formula (1), X represents at least one functional group having a nitrile oxide group selected from the group consisting of the following formulae (2a) and (2b): [In formula (2a), x1 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and l represents an integer of 1 to 4. In the formula, when l is 2 or more, x1 may be the same or different. In formula (2b), x2 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and m represents an integer of 1 to 4. In the formula, when m is 2 or more, x2 may be the same or different. In formula (2b), x3 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and n represents an integer of 1 to 2. In the formula, when n is 2, x3 may be the same or different.] A represents a spacer moiety represented by the following formula (3): [In formula (3), a1 and a2 are the same or different and each represent at least one element selected from the group consisting of CH, NH, oxygen (O), and sulfur (S). In formula (3), n represents an integer of 0 to 10.] The rubber composition according to item 1.

[0015] Item 4. The compound represented by formula (1) and / or a salt thereof is 2. The rubber composition according to claim 1, wherein the compound is at least one compound selected from the group consisting of:

[0016] Item 5. The rubber composition according to Item 1, wherein the rubber component is a polymer containing conjugated diene units and / or olefin units.

[0017] Item 6. The rubber composition according to Item 1, wherein the rubber component is at least one rubber component selected from the group consisting of natural rubber, isoprene rubber, styrene-butadiene copolymer rubber, butadiene rubber, and ethylene-propylene-diene rubber (EPDM).

[0018] Item 7. The rubber composition according to Item 1, further comprising carbon black and / or an inorganic filler.

[0019] Item 8. The rubber composition according to item 1, comprising 30 parts by mass to 150 parts by mass of the carbon black and / or inorganic filler per 100 parts by mass of the rubber component.

[0020] Item 9. The rubber composition according to Item 1, comprising 0.01 to 30 parts by mass of the compound represented by formula (1) and / or a salt thereof per 100 parts by mass of the rubber component.

[0021] Item 10. A tire made using the rubber composition according to any one of items 1 to 9.

[0022] Item 11. A low heat buildup agent for rubber, comprising a compound represented by the following formula (1) and / or a salt thereof: [In formula (1), X represents a functional group having a nitrile oxide group. In formula (1), A represents a spacer moiety. In formula (1), Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position.]

[0023] Item 12. The low heat buildup agent for rubber according to Item 11, wherein in formula (1), Y represents at least one functional group selected from the group consisting of the following formulas (4a), (4b), (4c), and (4d): [In formulas (4a), (4b), (4c), and (4d), y1 and y2 may be the same or different and each represent a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S).]

[0024] Item 13. In the formula (1), X represents at least one functional group having a nitrile oxide group selected from the group consisting of the following formulae (2a) and (2b): [In formula (2a), x1 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and l represents an integer of 1 to 4. In the formula, when l is 2 or more, x1 may be the same or different. In formula (2b), x2 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and m represents an integer of 1 to 4. In the formula, when m is 2 or more, x2 may be the same or different. In formula (2b), x3 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and n represents an integer of 1 to 2. In the formula, when n is 2, x3 may be the same or different.] A represents a spacer moiety represented by the following formula (3): [In formula (3), a1 and a2 are the same or different and each represent at least one element selected from the group consisting of CH, NH, oxygen (O), and sulfur (S). In formula (3), n represents an integer of 0 to 10.] The low heat buildup agent for rubber according to item 11.

[0025] Item 14. The compound represented by formula (1) and / or a salt thereof is Item 12. The low heat buildup agent for rubber according to Item 11, which is at least one compound selected from the group consisting of:

[0026] The rubber composition of the present invention is obtained by combining a rubber component with a compound (crosslinking agent) having a specific functional group having a nitrile oxide group, a specific spacer moiety, and a triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl group, which may have a substituent at a substitutable position, and exhibits excellent low heat buildup in the vulcanized rubber. Tires manufactured using this rubber composition also have improved fuel economy.

[0027] The present invention can provide a rubber composition having excellent low heat buildup (fuel economy) in the form of vulcanized rubber.

[0028] The present invention will be described in detail below. The embodiments of the present invention are intended to provide a better understanding of the gist of the invention, and unless otherwise specified, do not limit the content of the invention.

[0029] In this specification, the terms "comprise" and "contain" are concepts that encompass all of "comprise," "consist essentially of," and "consist only of."

[0030] In this specification, when a numerical range is expressed as "A to B," it means "A or more, and B or less."

[0031] In this specification, when the terms "parts," "%," and the like are used, they generally represent parts by mass, parts by weight, mass % (wt%), or weight % (wt%).

[0032] [1] Rubber Composition The rubber composition of the present invention contains a rubber component and a compound represented by the following formula (1) and / or a salt thereof.

[0033]

[0034] In formula (1), X represents a functional group having a nitrile oxide group.

[0035] In formula (1), A represents a spacer moiety.

[0036] In formula (1), Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position. In formula (1), Y preferably represents at least one functional group selected from the group consisting of the following formulae (4a), (4b), (4c), and (4d):

[0037]

[0038] In formulas (4a), (4b), (4c), and (4d), y1 and y2 may be the same or different and each represent a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S).

[0039] In formula (1), X preferably represents at least one functional group having a nitrile oxide group selected from the group consisting of the following formulae (2a) and (2b):

[0040]

[0041] In formula (2a), x1 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and l represents an integer of 1 to 4. In the formula, when l is 2 or more, x1 may be the same or different.

[0042] In formula (2b), x2 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and m represents an integer of 1 to 4. In the formula, when m is 2 or more, x2 may be the same or different.

[0043] In formula (2b), x3 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and n represents an integer of 1 to 2. In the formula, when n is 2, x3 may be the same or different.

[0044] In formula (1), A preferably represents a spacer moiety represented by the following formula (3).

[0045]

[0046] In formula (3), a1 and a2 are preferably the same or different and each represent at least one element selected from the group consisting of CH2, NH, oxygen (O), and sulfur (S).

[0047] In formula (3), n preferably represents an integer of 0 to 10.

[0048] The compound represented by formula (1) and / or a salt thereof is preferably at least one compound selected from the group consisting of the following compounds and / or a salt thereof:

[0049]

[0050]

[0051] The rubber component is preferably a polymer containing conjugated diene units and / or olefin units, and more preferably at least one rubber component selected from the group consisting of natural rubber, isoprene rubber, styrene-butadiene copolymer rubber, butadiene rubber, and ethylene-propylene-diene rubber.

[0052] The rubber composition of the present invention preferably further contains carbon black and / or an inorganic filler.

[0053] The rubber composition of the present invention is obtained by combining a rubber component with a compound (crosslinking agent) having a specific functional group having a nitrile oxide group, a specific spacer moiety, and a triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl group, which may have a substituent at a substitutable position, and exhibits excellent low heat buildup in the vulcanized rubber. Tires manufactured using this rubber composition also have improved fuel economy.

[0054] [1-1] Rubber Component The rubber composition of the present invention contains a rubber component.

[0055] The rubber component is not particularly limited, and is preferably a polymer containing conjugated diene units and / or olefin units, more preferably natural rubber (NR), synthetic diene rubber, a mixture of natural rubber and synthetic diene rubber, and other non-diene rubbers.

[0056] The natural rubber (NR) is preferably natural rubber latex, technically graded rubber (TSR), smoked sheet rubber (RSS), gutta percha, eucommia-derived natural rubber, guayule-derived natural rubber, Russian dandelion-derived natural rubber, or the like.

[0057] Natural rubber (NR) includes modified natural rubber and modified natural rubber obtained by modifying the natural rubber. Examples of modified natural rubber include epoxidized natural rubber, methacrylic acid-modified natural rubber, and styrene-modified natural rubber. Examples of modified natural rubber include highly purified natural rubber.

[0058] The synthetic diene rubber is preferably a styrene-butadiene copolymer rubber (SBR), a butadiene rubber (BR), an isoprene rubber (IR), a nitrile rubber (NBR), a chloroprene rubber (CR), an ethylene-propylene-diene terpolymer rubber (EPDM), a styrene-isoprene-styrene triblock copolymer (SIS), a styrene-butadiene-styrene triblock copolymer (SBS), or the like.

[0059] The synthetic diene rubber includes a modified synthetic diene rubber obtained by modifying the synthetic diene rubber. The modified synthetic diene rubber preferably includes a diene rubber modified by a modification method such as main chain modification, single-end modification, or both-end modification. The modified functional group of the modified synthetic diene rubber is preferably an epoxy group, an amino group, an alkoxysilyl group, a hydroxyl group, or other functional group, and one or more of these functional groups may be contained in the modified synthetic diene rubber.

[0060] The method for producing the synthetic diene rubber is not particularly limited, and may be emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, cationic polymerization, etc. The glass transition temperature of the synthetic diene rubber is not particularly limited.

[0061] There are no particular limitations on the cis / trans / vinyl ratio of the double bonds in the natural rubber and synthetic diene rubber, and any ratio can be suitably used.

[0062] The number average molecular weight and molecular weight distribution of the diene rubber are not particularly limited, but the number average molecular weight is preferably about 500 to 3,000,000, and the molecular weight distribution is preferably about 1.5 to 15.

[0063] The rubber component may be one of these rubber components or a mixture (blend) of two or more of them.

[0064] The rubber composition preferably contains, as a rubber component, at least one rubber component selected from the group consisting of the above-mentioned rubber components, more preferably at least one rubber component selected from the group consisting of NR, IR, SBR, EPDM, and BR, and even more preferably at least one rubber component selected from the group consisting of NR and IR.

[0065] There are no particular limitations on the blend ratio of the rubber components in the rubber composition, but the blend ratio of the rubber components is preferably 50 to 100 parts by mass, more preferably 75 to 100 parts by mass, of at least one rubber component (a mixture of two or more types) selected from the group consisting of NR and IR per 100 parts by mass of the rubber components.

[0066] [1-2] Compound Represented by Formula (1) and / or Salt Thereof The rubber composition of the present invention contains a compound represented by the following formula (1) and / or a salt thereof.

[0067]

[0068] X in Formula (1) In formula (1), X represents a functional group containing a nitrile oxide group (R-CNO).

[0069] In formula (1), X preferably represents at least one functional group having a nitrile oxide group selected from the group consisting of the following formulae (2a) and (2b):

[0070]

[0071] In formula (2a), x1 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and l represents an integer of 1 to 4. In the formula, when l is 2 or more, x1 may be the same or different. l is preferably an integer of 1 to 3, and more preferably an integer of 1 or 2.

[0072] In formula (2b), x2 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and m represents an integer of 1 to 4. In the formula, when m is 2 or more, x2 may be the same or different. m is preferably an integer of 1 to 3, and more preferably an integer of 1 or 2.

[0073] In formula (2b), x3 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and n represents an integer of 1 to 2. In the formula, when n is 2, x3 may be the same or different.

[0074] The alkyl group is not particularly limited. Examples of the alkyl group include linear, branched, and cyclic alkyl groups. Specific examples of the alkyl group include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, and 1-ethylpropyl.

[0075] Specific examples of the alkyl group include linear or branched alkyl groups having 5 to 18 carbon atoms, such as n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl, 3-methylpentyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, 5-propylnonyl, n-tridecyl, n-tetradecyl, n-pentadecyl, hexadecyl, heptadecyl, and octadecyl.

[0076] Specific examples of the alkyl group include cyclic alkyl groups having 3 to 8 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

[0077] The alkoxy group is not particularly limited. The alkoxy group may be a linear, branched, or cyclic alkoxy group. Specific examples of the alkoxy group include linear or branched alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, t-butoxy, n-pentyloxy, neopentyloxy, and n-hexyloxy.

[0078] Specific examples of the alkoxy group include cyclic alkoxy groups such as cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, cycloheptyloxy, and cyclooctyloxy groups.

[0079] The aryl group is not particularly limited, and specific examples of the aryl group include phenyl, biphenyl, naphthyl, dihydroindenyl, and 9H-fluorenyl groups.

[0080] Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and preferred examples include a chlorine atom, a bromine atom, and an iodine atom.

[0081] A in Formula (1) In formula (1), A represents a spacer moiety.

[0082] In formula (1), A preferably represents a spacer moiety represented by the following formula (3).

[0083]

[0084] In formula (3), a1 and a2 are preferably the same or different and each represent at least one element selected from the group consisting of CH2, NH, oxygen (O), and sulfur (S).

[0085] In formula (3), n is preferably an integer of 0 to 10, and more preferably an integer of 0 to 7.

[0086] The spacer moiety is an alkylene group containing a nitrogen atom (N), an oxygen atom (O), and / or a sulfur atom (S), such as an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, or a heptamethylene group. Specific examples of the spacer moiety include -O-CH2CH2-, -O-CH2CH2CH2- (propyl ether group), -O-CH2CH2CH2CH2-, -O-CH2CH2CH2CH2-, -O-CH2CH2CH2CH2-O-, -O-CH2CH2CH2-O- (butyl diether group), -O-CH2CH2CH2CH2CH2-O-, and the like.

[0087] Y in Formula (1) In formula (1), Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position.

[0088] In formula (1), Y preferably represents at least one functional group selected from the group consisting of the following formulae (4a), (4b), (4c), and (4d):

[0089]

[0090] In formulas (4a), (4b), (4c), and (4d), y1 and y2 may be the same or different and each represent a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S).

[0091] The heterocyclic group is not particularly limited. Specific examples of the heterocyclic group include 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrazinyl, 2-pyrimidyl, 4-pyrimidyl, 5-pyrimidyl, 3-pyridazyl, 4-pyridazyl, 4-(1,2,3-triazyl), 5-(1,2,3-triazyl), 2-(1,3,5-triazyl), 3-(1,2,4-triazyl), 5-(1,2,4-triazyl), and 6-(1,2,4-triazyl).

[0092] Specific examples of the heterocyclic group include 2-quinolyl, 3-quinolyl, 4-quinolyl, 5-quinolyl, 6-quinolyl, 7-quinolyl, 8-quinolyl, 1-isoquinolyl, 3-isoquinolyl, 4-isoquinolyl, 5-isoquinolyl, 6-isoquinolyl, 7-isoquinolyl, 8-isoquinolyl, 2-quinoxalyl, 3-quinoxalyl, 5-quinoxalyl, 6-quinoxalyl, 7-quinoxalyl, 8-quinoxalyl, 3-cinnolyl, 4-cinnolyl, 5-cinnolyl, 6-cinnolyl, 7-cinnolyl, and 8-cinnolyl.

[0093] Specific examples of heterocyclic groups include 2-quinazolyl, 4-quinazolyl, 5-quinazolyl, 6-quinazolyl, 7-quinazolyl, 8-quinazolyl, 1-phthalazyl, 4-phthalazyl, 5-phthalazyl, 6-phthalazyl, 7-phthalazyl, 8-phthalazyl, 1-tetrahydroquinolyl, 2-tetrahydroquinolyl, 3-tetrahydroquinolyl, 4-tetrahydroquinolyl, 5-tetrahydroquinolyl, 6-tetrahydroquinolyl, 7-tetrahydroquinolyl, and 8-tetrahydroquinolyl.

[0094] Specific examples of heterocyclic groups include 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, 2-furyl, 3-furyl, 2-thienyl, 3-thienyl, 1-imidazolyl, 2-imidazolyl, 4-imidazolyl, 5-imidazolyl, 1-pyrazolyl, 3-pyrazolyl, 4-pyrazolyl, 5-pyrazolyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl, 3-isothiazolyl, 4-isothiazolyl, and 5-isothiazolyl.

[0095] Specific examples of heterocyclic groups include 4-(1,2,3-thiadiazolyl), 5-(1,2,3-thiadiazolyl), 3-(1,2,5-thiadiazolyl), 2-(1,3,4-thiadiazolyl), 4-(1,2,3-oxadiazolyl), 5-(1,2,3-oxadiazolyl), 3-(1,2,4-oxadiazolyl), 5-(1,2,4-oxadiazolyl), 3-(1,2,5-oxadiazolyl), 2-(1,3,4-oxadiazolyl), 1-(1,2,3-triazolyl), 4-(1,2,3-triazolyl), 5-(1,2,3-triazolyl), 1-(1,2,4-triazolyl), 3-(1,2,4-triazolyl), and 5-(1,2,4-triazolyl).

[0096] Specific examples of the heterocyclic group include 1-tetrazolyl, 5-tetrazolyl, 1-indolyl, 2-indolyl, 3-indolyl, 4-indolyl, 5-indolyl, 6-indolyl, 7-indolyl, 1-isoindolyl, 2-isoindolyl, 3-isoindolyl, 4-isoindolyl, 5-isoindolyl, 6-isoindolyl, 7-isoindolyl, 1-benzimidazolyl, 2-benzimidazolyl, 4-benzimidazolyl, 5-benzimidazolyl, 6-benzimidazolyl, and 7-benzimidazolyl.

[0097] Specific examples of heterocyclic groups include 2-benzofuranyl, 3-benzofuranyl, 4-benzofuranyl, 5-benzofuranyl, 6-benzofuranyl, 7-benzofuranyl, 1-isobenzofuranyl, 3-isobenzofuranyl, 4-isobenzofuranyl, 5-isobenzofuranyl, 6-isobenzofuranyl, 7-isobenzofuranyl, 2-benzothienyl, 3-benzothienyl, 4-benzothienyl, 5-benzothienyl, 6-benzothienyl, and 7-benzothienyl.

[0098] Specific examples of the heterocyclic group include 2-benzoxazolyl, 4-benzoxazolyl, 5-benzoxazolyl, 6-benzoxazolyl, 7-benzoxazolyl, 2-benzothiazolyl, 4-benzothiazolyl, 5-benzothiazolyl, 6-benzothiazolyl, 7-benzothiazolyl, 1-indazolyl, 3-indazolyl, 4-indazolyl, 5-indazolyl, 6-indazolyl, 7-indazolyl, 2-morpholyl, 3-morpholyl, 4-morpholyl, 1-piperazyl, 2-piperazyl, 1-piperidyl, 2-piperidyl, 3-piperidyl, and 4-piperidyl.

[0099] Specific examples of the heterocyclic group include 2-tetrahydropyranyl, 3-tetrahydropyranyl, 4-tetrahydropyranyl, 2-tetrahydrothiopyranyl, 3-tetrahydrothiopyranyl, 4-tetrahydrothiopyranyl, 1-pyrrolidyl, 2-pyrrolidyl, 3-pyrrolidyl, furanyl, 2-tetrahydrofuranyl, 3-tetrahydrofuranyl, 2-tetrahydrothienyl, 3-tetrahydrothienyl, and 5-methyl-3-oxo-2,3-dihydro-1H-pyrazol-4-yl groups.

[0100] The aryl group is not particularly limited, and specific examples of the aryl group include phenyl, biphenyl, naphthyl, dihydroindenyl, and 9H-fluorenyl groups.

[0101] The alkyl group is not particularly limited. Examples of the alkyl group include linear, branched, and cyclic alkyl groups. Specific examples of the alkyl group include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, and 1-ethylpropyl.

[0102] Specific examples of the alkyl group include linear or branched alkyl groups having 5 to 18 carbon atoms, such as n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl, 3-methylpentyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, 5-propylnonyl, n-tridecyl, n-tetradecyl, n-pentadecyl, hexadecyl, heptadecyl, and octadecyl.

[0103] Specific examples of the alkyl group include cyclic alkyl groups having 3 to 8 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

[0104] The alkoxy group is not particularly limited. The alkoxy group may be a linear, branched, or cyclic alkoxy group. Specific examples of the alkoxy group include linear or branched alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, t-butoxy, n-pentyloxy, neopentyloxy, and n-hexyloxy.

[0105] Specific examples of the alkoxy group include cyclic alkoxy groups such as cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, cycloheptyloxy, and cyclooctyloxy groups.

[0106] The alkylthio group is not particularly limited. The alkylthio group may be a linear, branched, or cyclic alkylthio group. Specific examples of the alkylthio group include linear or branched alkylthio groups such as methylthio, ethylthio, n-propylthio, isopropylthio, n-butylthio, t-butylthio, n-pentylthio, neopentylthio, and n-hexylthio.

[0107] Specific examples of the alkylthio group include cyclic alkylthio groups such as cyclopropylthio, cyclobutylthio, cyclopentylthio, cyclohexylthio, cycloheptylthio, and cyclooctylthio.

[0108] In formulae (4a), (4b), (4c), and (4d), y1 and y2 are preferably the same or different and each represents a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S).

[0109] A compound represented by formula (1) and / or a salt thereof

[0110] The compound represented by formula (1) and / or a salt thereof is preferably at least one compound selected from the group consisting of the following compounds and / or a salt thereof:

[0111]

[0112]

[0113] The compound represented by formula (1) may be in the form of a salt, and the salt of the compound represented by formula (1) is not particularly limited and includes all kinds of salts.

[0114] Examples of such salts include inorganic acid salts such as hydrochloride, sulfate, and nitrate; organic acid salts such as acetate and methanesulfonate; alkali metal salts such as sodium salt and potassium salt; alkaline earth metal salts such as magnesium salt and calcium salt; and ammonium salts such as dimethylammonium and triethylammonium.

[0115] The rubber composition of the present invention contains, relative to 100 parts by mass of the rubber component, 0.01 to 30 parts by mass of the compound represented by formula (1) and / or a salt thereof, preferably 0.1 to 20 parts by mass, more preferably 0.2 to 10 parts by mass, even more preferably 0.25 to 5 parts by mass, and particularly preferably 0.3 to 3 parts by mass.

[0116] The rubber composition of the present invention contains the compound represented by formula (1) and / or its salt in an amount of preferably 0.01 to 30 parts by mass, preferably 0.1 to 20 parts by mass, more preferably 0.2 to 10 parts by mass, even more preferably 0.25 to 5 parts by mass, and particularly preferably 0.3 to 3 parts by mass, based on 100 parts by mass in total of isoprene rubber and / or natural rubber.

[0117] The rubber composition of the present invention is obtained by combining a rubber component with a compound (crosslinking agent) having a specific functional group having a nitrile oxide group, a specific spacer moiety, and a triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl group, which may have a substituent at a substitutable position, and exhibits excellent low heat buildup in the vulcanized rubber. Tires manufactured using this rubber composition also have improved fuel economy.

[0118] Among the triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl groups which may have a substituent at the substitutable position, preferred are triazyl, pyridyl, pyridazyl, or pyrimidyl groups having a specific substituent, and more preferred are pyridazyl or pyridyl groups having a specific heterocyclic group.

[0119] [1-3] Carbon Black and / or Inorganic Filler The rubber composition of the present invention preferably further contains carbon black and / or an inorganic filler. In this specification, the inorganic filler does not include carbon black.

[0120] Carbon black is used to improve the reinforcing properties of rubber. By including carbon black in the rubber component, it is possible to lower the electrical resistance of the rubber, suppress static electricity, and further improve the strength of the rubber.

[0121] The carbon black is not particularly limited, and examples of the carbon black include commercially available carbon black and carbon-silica dual phase filler.

[0122] The carbon black is preferably a high, medium or low structure SAF, ISAF, IISAF, N110, N134, N220, N234, N330, N339, N375, N550, HAF, FEF, GPF, SRF grade carbon black, etc. The carbon black is preferably a SAF, ISAF, IISAF, N134, N234, N330, N339, N375, HAF, FEF grade carbon black.

[0123] The DBP absorption range of the carbon black is preferably 60 cm 3 / 100g~200cm 3 / 100g, more preferably 70cm 3 / 100g~180cm 3 / 100g, particularly preferably 80cm 3 / 100g~160cm 3 / 100g.

[0124] The nitrogen adsorption specific surface area (N2SA) of carbon black is measured in accordance with JIS K6217-2:2001. The nitrogen adsorption specific surface area of ​​carbon black is preferably in the range of 30 m 2 / g~200m 2 / g, more preferably 40m 2 / g~180m 2 / g, and particularly preferably 50m 2 / g~160m 2 / g.

[0125] Inorganic Filler There are no particular limitations on the inorganic filler, and inorganic compounds commonly used in the rubber industry can be used.

[0126] The inorganic compound is preferably silica. The inorganic compound is preferably alumina (Al2O3) such as γ-alumina or α-alumina. The inorganic compound is preferably alumina monohydrate (Al2O3.H2O) such as boehmite or diaspore. The inorganic compound is preferably aluminum hydroxide [Al(OH)3] such as gibbsite or bayerite. The inorganic compound is preferably a crystalline aluminosilicate containing hydrogen, alkali metal, or alkaline earth metal to compensate for the charge, such as various zeolites.

[0127] The inorganic compound is preferably aluminum carbonate [Al2(CO3)3], magnesium hydroxide [Mg(OH)2], magnesium oxide (MgO), magnesium carbonate (MgCO3), talc (3MgO.4SiO2.H2O), attapulgite (5MgO.8SiO2.9H2O), titanium white (TiO2), titanium black (TiO 2n-1), calcium oxide (CaO), calcium hydroxide [Ca(OH)2], aluminum magnesium oxide (MgO·Al2O3), clay (Al2O3·2SiO2), kaolin (Al2O3·2SiO2·2H2O), pyrophyllite (Al2O3·4SiO2·H2O), bentonite (Al2O3·4SiO2·2H2O), aluminum silicate (Al2SiO5, Al4·3SiO4·5H2O, etc.), magnesium silicate (Mg2SiO4, MgSiO3, etc.), calcium silicate (Ca2·SiO4, etc.), aluminum calcium silicate (Al2O3·CaO·2SiO2, etc.), magnesium calcium silicate (CaMgSiO4), calcium carbonate (CaCO3), zirconium oxide (ZrO2), zirconium hydroxide [ZrO(OH)2·nH2O], zirconium carbonate [Zr(CO3)2], zinc acrylate, zinc methacrylate, etc.

[0128] The inorganic filler may preferably be an inorganic compound whose surface has been organically treated in order to improve its affinity with the rubber component.

[0129] The inorganic filler is preferably silica from the viewpoint of being able to impart rubber strength. The silica is preferably wet silica, dry silica, or colloidal silica, more preferably wet silica. The silica may preferably have its surface organically treated to improve affinity with the rubber component.

[0130] The BET specific surface area of ​​silica is measured in accordance with ISO 5794 / 1. The range of the BET specific surface area of ​​silica is preferably 40 m 2 / g~350m 2 / g. Silica having a BET specific surface area in this range has the advantage of being able to achieve both rubber reinforcement and dispersibility in the rubber component. The BET specific surface area of ​​the silica is more preferably 80 m 2 / g~300m 2 / g, more preferably 100m 2 / g~270m 2 / g, and particularly preferably 110m 2 / g~270m 2 / g.

[0131] Commercially available silica products include, for example, the product name "HD165MP" (BET specific surface area = 165 m) manufactured by Quechen Silicon Chemical Co., Ltd. 2 / g), "HD115MP" (BET specific surface area = 115m 2 / g), "HD200MP" (BET specific surface area = 200m 2 / g), "HD250MP" (BET specific surface area = 250m 2 / g), and Tosoh Silica Corporation's product name "Nipsil AQ" (BET specific surface area = 205 m 2 / g), "Nipsil KQ" (BET specific surface area = 240 m 2 / g), and Ultrasil VN3 (BET specific surface area = 175 m) manufactured by Degussa. 2 / g), etc.

[0132] The carbon black and / or inorganic filler may be used alone or in combination (blended) of two or more kinds.

[0133] The rubber composition of the present invention preferably contains 20 to 200 parts by mass of carbon black and / or inorganic filler per 100 parts by mass of the rubber component, more preferably 30 to 150 parts by mass, and even more preferably 35 to 110 parts by mass. When both carbon black and inorganic filler are compounded, the total amount of both components may be appropriately adjusted so that it falls within the above range.

[0134] The amount of carbon black and / or inorganic filler added is preferably 20 parts by mass or more from the viewpoint of improving the reinforcing properties of the rubber composition, and is preferably 200 parts by mass or less from the viewpoint of improving the tear strength.

[0135] The amount of carbon black added is preferably 2 to 200 parts by mass, more preferably 30 to 130 parts by mass, and even more preferably 35 to 100 parts by mass, per 100 parts by mass of the rubber component. The amount of carbon black added is preferably 2 parts by mass or more from the viewpoint of ensuring antistatic performance and rubber strength performance, and is preferably 200 parts by mass or less from the viewpoint of improving tear strength.

[0136] The blending amount of the inorganic filler is preferably 2 to 200 parts by mass, more preferably 30 to 130 parts by mass, and even more preferably 35 to 100 parts by mass, per 100 parts by mass of the rubber component. When silica is used as the inorganic filler, the blending amount of silica is preferably 2 to 200 parts by mass, more preferably 30 to 130 parts by mass, and even more preferably 35 to 100 parts by mass, per 100 parts by mass of the rubber component.

[0137] Silane Coupling Agents, etc. When the rubber composition of the present invention contains an inorganic filler such as carbon black or silica, a silane coupling agent, titanate coupling agent, aluminate coupling agent, zirconate coupling agent, etc. may be compounded into the rubber composition for the purpose of further increasing the reinforcing properties of the rubber composition by the carbon black, silica, etc., and for the purpose of further increasing the tear strength and abrasion resistance of the rubber composition.

[0138] The silane coupling agent is preferably a sulfide-based, polysulfide-based, thioester-based, thiol-based, olefin-based, epoxy-based, amino-based, alkyl-based or other silane coupling agent.

[0139] The titanate coupling agent is preferably an alkoxide-based, chelate-based, or acylate-based titanate coupling agent.

[0140] The zirconate coupling agent is preferably an alkoxide-based, chelate-based, or acylate-based zirconate coupling agent.

[0141] The silane coupling agent, titanate coupling agent, aluminate coupling agent, or zirconate coupling agent may be used alone or in combination (blended) of two or more.

[0142] In the rubber composition of the present invention, the blending amount of the silane coupling agent, titanate coupling agent, aluminate coupling agent, or zirconate coupling agent is preferably 0.1 to 20 parts by mass, more preferably 3 to 15 parts by mass, per 100 parts by mass of carbon black and / or inorganic filler. By setting the blending amount of the silane coupling agent, titanate coupling agent, aluminate coupling agent, or zirconate coupling agent to 0.1 part by mass or more per 100 parts by mass of carbon black and / or inorganic filler, the effect of improving the tear strength of the rubber composition can be more suitably exhibited, and by setting the blending amount to 20 parts by mass or less, the cost of the rubber composition can be reduced, improving economy.

[0143] [1-4] Other Compounding Agents The rubber composition of the present invention may contain, in addition to the rubber component, the compound represented by formula (1) and / or its salt, and, as necessary, carbon black and / or an inorganic filler, other compounding agents commonly used in the rubber industry, as appropriate.

[0144] Examples of compounding agents include antioxidants, antiozonants, softeners, processing aids, waxes, resins, foaming agents, oils, zinc oxide (ZnO), stearic acid, vulcanization accelerators, vulcanization retarders, and vulcanizing agents (sulfur, etc.).

[0145] The rubber composition of the present invention is obtained by combining a rubber component with a compound (crosslinking agent) having a specific functional group having a nitrile oxide group, a specific spacer moiety, and a triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl group, which may have a substituent at a substitutable position, and exhibits excellent low heat buildup in the vulcanized rubber. Tires manufactured using this rubber composition also have improved fuel economy.

[0146] [2] Low-heat-generating agent for rubber The present invention encompasses a low-heat-generating agent for rubber, which comprises a compound represented by the following formula (1) and / or a salt thereof:

[0147]

[0148] In formula (1), X represents a functional group having a nitrile oxide group.

[0149] In formula (1), A represents a spacer moiety.

[0150] In formula (1), Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position.

[0151] In formula (1), Y preferably represents at least one functional group selected from the group consisting of the following formulae (4a), (4b), (4c), and (4d):

[0152]

[0153] In formulas (4a), (4b), (4c), and (4d), y1 and y2 may be the same or different and each represent a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S).

[0154] In formula (1), X preferably represents at least one functional group having a nitrile oxide group selected from the group consisting of the following formulae (2a) and (2b):

[0155]

[0156] In formula (2a), x1 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and l represents an integer of 1 to 4. In the formula, when l is 2 or more, x1 may be the same or different.

[0157] In formula (2b), x2 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and m represents an integer of 1 to 4. In the formula, when m is 2 or more, x2 may be the same or different.

[0158] In formula (2b), x3 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and n represents an integer of 1 to 2. In the formula, when n is 2, x3 may be the same or different.

[0159] In formula (1), A preferably represents a spacer moiety represented by the following formula (3).

[0160]

[0161] In formula (3), a1 and a2 are preferably the same or different and each represent at least one element selected from the group consisting of CH2, NH, oxygen (O), and sulfur (S).

[0162] In formula (3), n preferably represents an integer of 0 to 10.

[0163] The compound represented by formula (1) and / or a salt thereof is preferably at least one compound selected from the group consisting of the following compounds and / or a salt thereof:

[0164]

[0165]

[0166] The compound represented by formula (1) and / or its salt contained in the low heat buildup agent for rubber of the present invention is the same as that described in the section [1] Rubber composition.

[0167] The rubber low heat generating agent of the present invention is required to apply to the rubber component a compounding agent containing a compound (crosslinking agent) having a functional group having a specific nitrile oxide group, a specific spacer moiety, and a triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl group, which may have a substituent at a substitutable position, and can exhibit superior low heat generating properties in vulcanized rubber. Tires manufactured using this rubber low heat generating agent in the rubber component can improve fuel economy.

[0168] Among the triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl groups which may have a substituent at the substitutable position, preferred are triazyl, pyridyl, pyridazyl, or pyrimidyl groups having a specific substituent, and more preferred are pyridazyl or pyridyl groups having a specific heterocyclic group.

[0169] [3] Method for producing rubber composition The present invention includes a method for producing the rubber composition of the present invention.

[0170] The rubber composition is preferably produced by any of the following methods 1 to 3.

[0171] <Method 1> A method comprising: (1) a step of kneading a rubber component and a compound represented by formula (1) and / or a salt thereof to prepare a masterbatch (MB); (2) a step of mixing components such as carbon black and / or an inorganic filler with the MB obtained in the step (1), followed by kneading to prepare an unvulcanized rubber composition; and (3) a step of mixing a vulcanizing agent (sulfur, etc.) with the unvulcanized rubber composition obtained in the step (2), followed by kneading.

[0172] <Method 2> A method comprising: (1) a step of kneading a rubber component and a compound represented by formula (1) and / or a salt thereof, followed by mixing components such as carbon black and / or an inorganic filler, and then kneading the mixture to prepare an unvulcanized rubber composition; and (2) a step of mixing a vulcanizing agent (sulfur, etc.) with the unvulcanized rubber composition obtained in step (1), followed by kneading the mixture.

[0173] <Method 3> A method comprising: (1) a step of kneading components such as a rubber component, a compound represented by formula (1) and / or a salt thereof, carbon black and / or an inorganic filler; and (2) a step of mixing a vulcanizing agent (sulfur, etc.) with the unvulcanized rubber composition obtained in the step (1), followed by kneading.

[0174] The contents described in the section [1] Rubber composition above apply to the rubber component, the compound represented by formula (1), and / or its salt, etc., used in the method for producing the rubber composition of the present invention.

[0175] <Method 1> Step (1) (Preparation of MB) In step (1), a rubber component and a compound represented by formula (1) and / or a salt thereof are mixed to prepare a master batch (MB). In step (1), an antioxidant, wax, etc. may be mixed.

[0176] In the step (1), the compound represented by formula (1) and / or its salt is mixed in an amount of 0.01 to 30 parts by mass, preferably 0.1 to 20 parts by mass, more preferably 0.2 to 10 parts by mass, still more preferably 0.25 to 5 parts by mass, and particularly preferably 0.3 to 3 parts by mass, per 100 parts by mass of the rubber component.

[0177] The kneading temperature in step (1) is preferably 60° C. to 190° C., more preferably 70° C. to 160° C., and even more preferably 80° C. to 150° C. By adjusting the kneading temperature to 60° C. to 190° C., the reaction proceeds smoothly and deterioration of the rubber can be suppressed.

[0178] The kneading time in step (1) is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and even more preferably 60 seconds to 7 minutes. By adjusting the kneading time to 10 seconds to 20 minutes, the reaction proceeds smoothly and productivity can be improved.

[0179] Step (2) In step (2), raw material components including carbon black and / or inorganic filler are added to the MB obtained in step (1), and if necessary, antioxidants, wax, stearic acid, etc. are added, followed by kneading to prepare an unvulcanized rubber composition.

[0180] In the kneading method, all of the components may be kneaded at once, or the components may be added in portions and kneaded depending on the purpose of viscosity adjustment, etc. In the kneading method, the kneading operation may be repeated to uniformly disperse the components.

[0181] The upper limit of the kneading temperature in step (2) is preferably 100°C to 190°C, more preferably 130°C to 175°C, and even more preferably 110°C to 170°C.

[0182] The kneading time in step (2) is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and even more preferably 60 seconds to 8 minutes.

[0183] When proceeding from step (2) to step (3), the mixture is preferably cured so that the maximum temperature of the mixture is 60°C or less.

[0184] Step (3) In step (3), a vulcanizing agent (sulfur, etc.) is added to the mixture (unvulcanized rubber composition) obtained in step (2), and zinc oxide, a vulcanization accelerator, etc. are added as needed, and mixed to produce an unvulcanized rubber composition. Step (3) is the final stage of kneading.

[0185] Step (3) is preferably carried out under heating conditions, and the heating temperature is preferably 60°C to 120°C, more preferably 65°C to 100°C.

[0186] The mixing (or kneading) time in step (3) is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and even more preferably 60 seconds to 5 minutes.

[0187] When proceeding from step (3) to the <vulcanization step>, the mixture is preferably cured so that the maximum temperature of the mixture is 70°C or less.

[0188] <Method 2> Step (1) In step (1), a rubber component and a compound represented by formula (1) and / or a salt thereof are mixed, and then components such as carbon black and / or an inorganic filler are mixed in. In step (1), an antioxidant, wax, etc. may be mixed before mixing components such as carbon black and / or an inorganic filler.

[0189] In the step (1), the compound represented by formula (1) and / or its salt is mixed in an amount of 0.01 to 30 parts by mass, preferably 0.1 to 20 parts by mass, more preferably 0.2 to 10 parts by mass, still more preferably 0.25 to 5 parts by mass, and particularly preferably 0.3 to 3 parts by mass, per 100 parts by mass of the rubber component.

[0190] The temperature at which the rubber component and the compound represented by formula (1) and / or its salt are mixed in step (1) is preferably 60° C. to 190° C., more preferably 70° C. to 160° C., and even more preferably 80° C. to 150° C. By adjusting the mixing temperature to 60° C. to 190° C., the reaction proceeds smoothly and deterioration of the rubber can be suppressed.

[0191] The time for mixing the rubber component and the compound represented by formula (1) and / or its salt in step (1) is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and even more preferably 60 seconds to 8 minutes. By adjusting the mixing time to 10 seconds to 20 minutes, the reaction proceeds smoothly and productivity can be improved.

[0192] The upper limit of the temperature at which components such as carbon black and / or inorganic filler are mixed in step (1) is preferably 100°C to 190°C, more preferably 100°C to 175°C, and even more preferably 110°C to 170°C.

[0193] The time for mixing components such as carbon black and / or inorganic filler in step (1) is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and even more preferably 60 seconds to 8 minutes.

[0194] When proceeding from step (1) to step (2), the mixture is preferably cured so that the maximum temperature of the mixture is 60°C or less.

[0195] In the kneading method, all of the components may be kneaded at once, or the components may be added in portions and kneaded depending on the purpose of viscosity adjustment, etc. In the kneading method, the kneading operation may be repeated to uniformly disperse the components.

[0196] Step (2) In step (2), a vulcanizing agent (sulfur, etc.) is added to the mixture (unvulcanized rubber composition) obtained in step (1), and zinc oxide, a vulcanization accelerator, etc. are added as needed, and mixed to produce an unvulcanized rubber composition. Step (2) is the final stage of kneading.

[0197] Step (2) is preferably carried out under heating conditions, and the heating temperature is preferably 60°C to 120°C, more preferably 65°C to 100°C.

[0198] The mixing (or kneading) time in step (2) is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and even more preferably 60 seconds to 5 minutes.

[0199] When proceeding from step (2) to the vulcanization step, the mixture is preferably cured so that the maximum temperature of the mixture is 70°C or less.

[0200] <Method 3> Step (1) In step (1), the rubber component, the compound represented by formula (1) and / or its salt, carbon black and / or an inorganic filler, and other components are kneaded together.

[0201] In the step (1), the compound represented by formula (1) and / or its salt is mixed in an amount of 0.01 to 30 parts by mass, preferably 0.1 to 20 parts by mass, more preferably 0.2 to 10 parts by mass, still more preferably 0.25 to 5 parts by mass, and particularly preferably 0.3 to 3 parts by mass, per 100 parts by mass of the rubber component.

[0202] The mixing temperature in step (1) is preferably 60° C. to 190° C., more preferably 70° C. to 160° C., and even more preferably 80° C. to 150° C. By adjusting the mixing temperature to 60° C. to 190° C., the reaction proceeds smoothly and rubber degradation can be suppressed.

[0203] The kneading time in step (1) is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and even more preferably 60 seconds to 7 minutes. By adjusting the mixing time to 10 seconds to 20 minutes, the reaction proceeds smoothly and productivity can be improved.

[0204] When proceeding from step (1) to step (2), the mixture is preferably cured so that the maximum temperature of the mixture is 60°C or less.

[0205] In the kneading method, the kneading operation may be repeated to uniformly disperse each component.

[0206] Step (2) In step (2), a vulcanizing agent (sulfur, etc.) is added to the mixture (unvulcanized rubber composition) obtained in step (1), and zinc oxide, a vulcanization accelerator, etc. are added as needed, and mixed to produce an unvulcanized rubber composition. Step (2) is the final stage of kneading.

[0207] Step (2) is preferably carried out under heating conditions, and the heating temperature is preferably 60°C to 120°C, more preferably 65°C to 100°C.

[0208] The mixing (or kneading) time in step (2) is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and even more preferably 60 seconds to 5 minutes.

[0209] When proceeding from step (2) to the vulcanization step, the mixture is preferably cured so that the maximum temperature of the mixture is 70°C or less.

[0210] <Vulcanization step> After mixing a vulcanizing agent (sulfur, etc.) with a rubber composition (unvulcanized rubber composition), the mixture is vulcanized by heating (150°C x 25 minutes) using a vulcanization press to obtain a vulcanized rubber composition.

[0211] In the method for producing the rubber composition of the present invention, various compounding agents such as antioxidants, waxes, stearic acid, zinc oxide, vulcanization accelerators, etc. can be added as needed in steps (1) to (3) of Methods 1 to 3. The other compounding agents may be added in any one of steps (1) to (3) of Methods 1 to 3, or may be added separately in steps (1), (2), and (3).

[0212] The rubber composition of the present invention is obtained by combining a rubber component with a compound (crosslinking agent) having a specific functional group having a nitrile oxide group, a specific spacer moiety, and a triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl group, which may have a substituent at a substitutable position, and exhibits excellent low heat buildup in the vulcanized rubber. Tires manufactured using this rubber composition also have improved fuel economy.

[0213] [4] Tire The present invention includes a tire produced using the rubber composition of the present invention.

[0214] The rubber composition of the present invention is mixed or kneaded using a Banbury mixer, a roll, an intensive mixer, a kneader, a single-screw extruder, a twin-screw extruder, etc. Subsequently, in the extrusion step, the rubber composition is extruded and processed, and molded into, for example, a tread component or a sidewall component.

[0215] The rubber composition is then applied and molded into a green tire by a conventional method on a tire building machine, and the green tire is then heated and pressurized in a vulcanizer to obtain a tire.

[0216] Tires and Other Applications Tires are produced using the rubber composition of the present invention. The tires are preferably pneumatic tires (radial tires, bias tires, etc.), solid tires, etc. The tire applications are preferably passenger car tires, heavy-duty tires, motorcycle tires, studless tires, large tires for trucks, buses, etc. The tire applications are more preferably passenger car tires.

[0217] The shape, structure, size and material of the tire are not particularly limited and may be appropriately selected depending on the purpose.

[0218] The tire components are preferably a tread portion, a sidewall portion, a bead area portion, a belt portion, a carcass portion, a shoulder portion, etc., and more preferably a tire tread portion, a sidewall portion, etc.

[0219] The tread portion has a tread pattern and is the outer shell of the tire that directly contacts the road surface, protecting the carcass and preventing wear and damage. Within the tread portion, it refers to the cap tread that constitutes the tire's ground contact area and / or the base tread disposed inside the cap tread.

[0220] The sidewall portion is a portion of a pneumatic radial tire extending from the lower side of the shoulder portion to the bead portion, and protects the carcass and is the portion that is most subject to bending during running.

[0221] The bead area is the part that secures both ends of the carcass cord and also secures the tire to the rim. The bead is made of bundled high-carbon steel.

[0222] The belt is a reinforcing band stretched circumferentially between the radial tread and carcass. It tightens the carcass like a barrel hoop, increasing the rigidity of the tread.

[0223] The carcass is a cord layer portion that forms the skeleton of the tire, and serves to withstand the load, impact, and inflation pressure that the tire receives.

[0224] The shoulder portion is the shoulder part of the tire and serves to protect the carcass.

[0225] The tires are manufactured according to conventional methods in the field of tires. The gas used to fill the tires is normal or oxygen-adjusted air, or an inert gas such as nitrogen, argon, or helium.

[0226] The rubber composition of the present invention can be used not only for tires but also for various rubber members, preferably for vibration-proof rubber, seismic isolation rubber, and belts such as conveyor belts.

[0227] The rubber composition of the present invention is obtained by combining a rubber component with a compound (crosslinking agent) having a specific functional group having a nitrile oxide group, a specific spacer moiety, and a triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl group, which may have a substituent at a substitutable position, and exhibits excellent low heat buildup in the vulcanized rubber. Tires manufactured using this rubber composition also have improved fuel economy.

[0228] The present invention will be specifically described below by showing Production Examples and Examples, which are merely illustrative and are not intended to limit the scope of the present invention.

[0229] [1] Production of rubber compositions of examples and comparative examples [1-1] Production of compounds A and B Production Example 1: Production of compound A

[0230] <Step 1> 109.5 g of potassium carbonate was added to a solution of 113.6 g of 2-hydroxy-1-naphthaldehyde and 81.2 g of 5-chloro-1-pentyne in 300 mL of DMF (N,N-dimethylformamide), and the mixture was reacted for 24 hours at 100° C. After cooling the reaction solution, 1500 mL of water was added to stop the reaction, and the precipitated solid was filtered, washed with hexane, and dried to obtain 157.2 g of intermediate 1 (yield 99%).

[0231] 1 H-NMR (500MHz, DMSO-d6, δppm): 10.81 (1H, s), 9.11 (1H, m), 8.28 (1H, m), 7.95 (1H, s), 7.65 (1H, m), 7.63 (1H, m), 7.46 (1H, m), 4.38 (2H, t), 2.85 (1H, t), 2.42 (2H, m), 2.02 (2H, m)

[0232] <Step 2> 157.2 g of intermediate 1 was added to 450 mL of toluene, and 141.7 g of 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine was added to the solution, and the mixture was refluxed for 24 hours. After cooling the reaction solution, the precipitated solid was filtered, washed with toluene, and dried to obtain 244.2 g of intermediate 2 (yield 91%).

[0233] 1 H-NMR (500MHz, DMSO-d6, δppm): 10.63 (1H, s), 9.11 (1H, m), 8.74 (1H, m), 8.65 (1H, s), 8.61 (2H, m), 8.23 ​​(1H, m), 8.05 (1H, m), 7.97 (2H, m), 7.92 (1H, m), 7.65 (1H, m), 7.60 (1H, m), 7.55 (3H, m), 4.32 (2H, t), 3.26 (2H, m), 2.14 (2H, m)

[0234] <Step 3> 244.2 g of intermediate 2 was added to 800 mL of methanol, and to this solution, 114.0 g of hydroxylamine hydrochloride was added, and the mixture was reacted for 24 hours at 60° C. After cooling the reaction solution, 1600 mL of water was added to stop the reaction, and the precipitated solid was filtered, washed with water, and then dried to obtain 248.5 g of intermediate 3 (yield 99%).​​

[0235] 1 H-NMR (500MHz, DMSO-d6, δppm): 11.29 (1H, s), 8.85 (1H, m), 8.70 (1H, m), 8.60 (1H, m), 8.59 (3H, m), 8.00 (5H, m), 7.57 (2H, m), 7.40 (3H, m), 4.21 (2H, m), 3.23 (2H, m), 2.10 (2H, m)

[0236] <Step 4> 22.4 g of Intermediate 3 was added to 100 mL of methylene chloride, and 7.26 g of N-chlorosuccinimide was added to the solution while cooling in an ice bath. The mixture was warmed to room temperature and allowed to react for 24 hours. 500 mL of saturated aqueous sodium bicarbonate solution was added to the reaction mixture to terminate the reaction, and the methylene chloride layer was separated, washed with water, and then concentrated. The resulting solid was washed with acetone and dried to obtain 20.1 g (90% yield) of the desired compound A.

[0237] 1 H-NMR (500MHz, CDCl3, δppm): 8.73 (1H, m), 8.66 (2H, m), 8.57 (1H, s), 8.14 (1H, m), 7.96 (1H, m), 7.85 (4H, m), 7.61 (1H, m), 7.45 (1H, m), 7.38 (1H, m), 7.32 (1H, m), 7.17 (1H, m), 4.24 (2H, t), 3.68 (2H, m), 2.33 (2H, m)

[0238] Preparation Example 2: Preparation of Compound B

[0239] <Step 1> 82.9 g of potassium carbonate was added to a solution of 51.7 g of 2-hydroxy-1-naphthaldehyde and 194.3 g of 1,4-dibromobutane in 450 mL of acetone, and the mixture was refluxed for 24 hours. After cooling the reaction mixture, 500 mL of water was added to terminate the reaction, and the precipitated solid was filtered. The filtrate was extracted with methylene chloride, the solvent was distilled off, and the residue was purified by silica gel chromatography to obtain 69.5 g of intermediate 4 (yield 75%).

[0240] 1 ​​​H-NMR (500MHz, CDCl3, δppm): 10.92 (1H, s), 9.27 (1H, m), 8.05 (1H, m), 7.77 (1H, m), 7.63 (1H, m), 7.43 (1H, m), 7.26 (1H, m), 4.28 (2H, t), 3.52 (2H, t), 2.11 (4H, m)

[0241] <Step 2> 20.9 g of potassium carbonate was added to a solution of 40.6 g of intermediate 4 and 31.4 g of 2,6-bis(2-pyridyl)-4(1H)-pyridone in 132 mL of DMF, and the mixture was reacted for 24 hours at 90° C. After cooling the reaction solution, 1000 mL of water was added to stop the reaction, and the precipitated solid was filtered, washed with diethyl ether, and dried to obtain 53.8 g of intermediate 5 (yield 90%).

[0242] 1 H-NMR (500MHz, CDCl3, δppm): 10.94 (1H, s), 9.27 (1H, m), 8.67 (2H, m), 8.61 (2H, m), 8.00 (3H, m), 7.84 (2H, m), 7.76 (1H, m), 7.62 (1H, m), 7.33 (1H, m), 7.26 (3H, m), 4.34 (4H, m), 2.14 (4H, m)

[0243] <Step 3> 8.8 g of hydroxylamine hydrochloride was added to a solution of 30.2 g of intermediate 5 in 127 mL of methanol, and the mixture was allowed to react at room temperature for 24 hours. 1000 mL of water was added to the reaction solution to stop the reaction, and the precipitated solid was filtered, washed with methanol, and dried to obtain 29.6 g of intermediate 6 (yield 95%).

[0244] 1 H-NMR (500MHz, CDCl3, δppm): 10.77 (1H, s), 8.84 (1H, m), 8.71 (2H, m), 8.61 (2H, m), 8.52 (1H, m), 8.03 (2H, s), 7.86 (3H, m), 7.70 (1H, m), 7.50 (1H, m), 7.35 (3H, m), 7.26 (1H, m), 4.38 (2H, m), 4.22 (2H, m), 2.12 (4H, m)

[0245] ​​<Step 4> To a solution of 16.4 g of intermediate 6 in 400 mL of methylene chloride, 241.6 g of a 1% aqueous solution of sodium hypochlorite was added dropwise while cooling in an ice bath. The mixture was warmed to room temperature and allowed to react for 24 hours. The methylene chloride layer was separated, washed with water, and then concentrated. The resulting solid was washed with diethyl ether and dried to obtain 14.7 g (90% yield) of the target compound B.

[0246] 1 H-NMR (500MHz, CDCl3, δppm): 8.67 (2H, m), 8.60 (2H, m), 8.02 (2H, s), 7.95 (2H, m), 7.82 (3H, m), 7.60 (1H, m), 7.42 (1H, m), 7.33 (2H, m), 7.26 (1H, m), 4.34 (4H, m), 2.15 (4H, m)

[0247] [1-2] Production of Rubber Composition Step (1) (MB Preparation Step) In step (1) of Tables 1 and 2 below, the rubber component and the compound (crosslinking agent) represented by formula (1) were mixed in the ratio (parts by mass) to prepare a master batch (MB).

[0248] <Conditions for preparing MBs of Examples 1 and 3, and corresponding Comparative Examples 1 and 3> Mixing temperature: 140°C Mixing time: 4 minutes

[0249] <Preparation conditions for MBs of Examples 2 and 4, and corresponding Comparative Examples 2 and 4> Mixing temperature: 115°C Mixing time: 4 minutes

[0250] Step (2): Each MB obtained in step (1) was mixed with each of the components shown in step (2) in Tables 1 and 2 in the proportions (parts by mass) and kneaded in a Banbury mixer. The mixture was then cured until the temperature of the mixture reached 60°C or less to produce an unvulcanized rubber composition.

[0251] Process (3)

[0252] Each component shown in step (3) of Tables 1 and 2 was added to the unvulcanized rubber composition obtained in step (2) in the proportions (parts by mass) thereof, and the mixture was kneaded while adjusting the maximum temperature of the mixture to 70°C or less.

[0253] ​Vulcanization Step The unvulcanized rubber composition was vulcanized by heating at 150°C for 25 minutes using a vulcanization press to obtain a vulcanized rubber composition (rubber composition after vulcanization).

[0254] [2] Low heat buildup test: Measurement of Tan δ value The Tan δ value of the obtained vulcanized rubber composition was measured using a viscoelasticity measuring device (manufactured by Metravib) under the conditions of a temperature of 60°C, a dynamic strain of 5%, and a frequency of 15 Hz.

[0255] The examples are examples in which the compound represented by formula (1) is blended.

[0256] The low heat buildup index of the vulcanized rubber compositions of the Examples was expressed as an index when the Tan δ values ​​of Comparative Examples 1 and 2 (examples not containing the compound represented by formula (1)) were set to 100, and the low heat buildup index was calculated based on the following formula.

[0257] Formula: Low heat buildup index of Example 1 = (Tan δ value of vulcanized rubber composition of Example 1) / (Tan δ value of vulcanized rubber composition of Comparative Example 1) × 100

[0258] Formula: Low heat buildup index of Example 2 = (Tan δ value of vulcanized rubber composition of Example 2) / (Tan δ value of vulcanized rubber composition of Comparative Example 2) × 100

[0259] The smaller the low heat buildup index value, the more excellent the low heat buildup property of the vulcanized rubber composition and the smaller the hysteresis loss.

[0260] The results of the low heat generation index are shown in Table 1.

[0261]

[0262] The low heat buildup index of the vulcanized rubber compositions of the Examples was expressed as an index when the Tan δ values ​​of Comparative Examples 3 and 4 (examples not containing the compound represented by formula (1)) were set to 100, and the low heat buildup index was calculated based on the following formula.

[0263] Formula: Low heat buildup index of Example 3 = (Tan δ value of vulcanized rubber composition of Example 3) / (Tan δ value of vulcanized rubber composition of Comparative Example 3) × 100

[0264] Formula: Low heat buildup index of Example 4 = (Tan δ value of vulcanized rubber composition of Example 4) / (Tan δ value of vulcanized rubber composition of Comparative Example 4) × 100

[0265] The smaller the low heat buildup index value, the more excellent the low heat buildup property of the vulcanized rubber composition and the smaller the hysteresis loss.

[0266] The results of the low heat index are shown in Table 2.

[0267]

[0268] *1: Compound A (crosslinking agent) in Production Example 1

[0269] *2: Compound B (crosslinking agent) in Production Example 2

[0270] *3: Carbon black, N234 grade *4: Antioxidant, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine *5: Wax, Rhein Chemie Rheinau, Antilux 111 *6: Vulcanization accelerator, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)

[0271] [3] Explanation of low heat buildup The vulcanized rubber compositions containing the compound represented by formula (1) in Examples 1 to 4 had excellent low heat buildup properties compared to the vulcanized rubber compositions of Comparative Examples 1 to 4 (prior art).

[0272] The rubber composition of the present invention has a low low heat buildup index after vulcanization, and can be evaluated as having improved low heat buildup properties after vulcanization.

[0273] The rubber composition of the present invention is obtained by combining a rubber component with a compound (crosslinking agent) having a specific functional group having a nitrile oxide group, a specific spacer moiety, and a triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl group, which may have a substituent at a substitutable position, and exhibits excellent low heat buildup in the vulcanized rubber. Tires manufactured using this rubber composition also have improved fuel economy.

Claims

1. A rubber composition comprising a rubber component and a compound represented by the following formula (1) and / or a salt thereof: [In formula (1), X represents a functional group having a nitrile oxide group. In formula (1), A represents a spacer moiety. In formula (1), Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position.] 2. The rubber composition according to claim 1, wherein in formula (1), Y represents at least one functional group selected from the group consisting of the following formulas (4a), (4b), (4c), and (4d): [In formulas (4a), (4b), (4c), and (4d), y1 and y2 may be the same or different and each represent a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S).] 3. In the formula (1), X represents at least one functional group having a nitrile oxide group selected from the group consisting of the following formulae (2a) and (2b): [In formula (2a), x1 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and l represents an integer of 1 to 4. In the formula, when l is 2 or more, x1 may be the same or different. In formula (2b), x2 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and m represents an integer of 1 to 4. In the formula, when m is 2 or more, x2 may be the same or different. In formula (2b), x3 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and n represents an integer of 1 to 2. In the formula, when n is 2, x3 may be the same or different.] A represents a spacer moiety represented by the following formula (3): [In formula (3), a1 and a2 are the same or different and each represent at least one element selected from the group consisting of CH2, NH, oxygen (O), and sulfur (S). In formula (3), n represents an integer of 0 to 10.] The rubber composition according to claim 1.

4. The compound represented by formula (1) and / or a salt thereof is 2. The rubber composition according to claim 1, wherein the compound is at least one compound selected from the group consisting of:

5. The rubber composition according to claim 1, wherein the rubber component is a polymer containing conjugated diene units and / or olefin units.

6. The rubber composition according to claim 1, wherein the rubber component is at least one rubber component selected from the group consisting of natural rubber, isoprene rubber, styrene-butadiene copolymer rubber, butadiene rubber, and ethylene-propylene-diene rubber (EPDM).

7. The rubber composition according to claim 1, further comprising carbon black and / or an inorganic filler.

8. The rubber composition according to claim 1, comprising 30 to 150 parts by mass of the carbon black and / or inorganic filler per 100 parts by mass of the rubber component.

9. The rubber composition according to claim 1, comprising 0.01 to 30 parts by mass of the compound represented by formula (1) and / or a salt thereof per 100 parts by mass of the rubber component.

10. A tire made using the rubber composition according to any one of claims 1 to 9.

11. A low heat generating agent for rubber, comprising a compound represented by the following formula (1) and / or a salt thereof: [In formula (1), X represents a functional group having a nitrile oxide group. In formula (1), A represents a spacer moiety. In formula (1), Y represents triazyl, pyridyl, pyridazyl, pyrazyl, or pyrimidyl, which may have a substituent at a substitutable position.] 12. The low heat buildup agent for rubber according to claim 11, wherein in formula (1), Y represents at least one functional group selected from the group consisting of the following formulas (4a), (4b), (4c), and (4d): [In formulas (4a), (4b), (4c), and (4d), y1 and y2 may be the same or different and each represent a hydrogen atom, an aryl group, an alkyl group, an alkoxy group, an alkylthio group, or a heterocyclic group containing at least one element selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S).] 13. In the formula (1), X represents at least one functional group having a nitrile oxide group selected from the group consisting of the following formulae (2a) and (2b): [In formula (2a), x1 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and l represents an integer of 1 to 4. In the formula, when l is 2 or more, x1 may be the same or different. In formula (2b), x2 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and m represents an integer of 1 to 4. In the formula, when m is 2 or more, x2 may be the same or different. In formula (2b), x3 represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen atom, and n represents an integer of 1 to 2. In the formula, when n is 2, x3 may be the same or different.] A represents a spacer moiety represented by the following formula (3): [In formula (3), a1 and a2 are the same or different and each represent at least one element selected from the group consisting of CH2, NH, oxygen (O), and sulfur (S). In formula (3), n represents an integer of 0 to 10.] The low heat buildup agent for rubber according to claim 11.

14. The compound represented by the formula (1) and / or a salt thereof is 12. The low heat buildup agent for rubber according to claim 11, which is at least one compound selected from the group consisting of: and / or a salt thereof.

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