Rubber composition for metal bonding, steel belt, and pneumatic tire

Abstract

To provide a rubber composition having superior hardness and metal adhesion.SOLUTION: A metal-bonding rubber composition includes a diene rubber, a pyrazolone compound, and a metal complex.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber composition for metal bonding, a steel belt, and a pneumatic tire. [Background technology]

[0002] A pneumatic tire is primarily composed of a bead, sidewall, and tread, with a carcass layer on the inside. The tread consists of a cap tread and an under tread, and a belt layer is formed between the under tread and the carcass layer. Because this belt layer is subjected to strong impacts and loads, metal reinforcing cords, such as steel cords, are used as reinforcement. The rubber covering these steel cords is required to have strong adhesion to the steel cords. Furthermore, the rubber covering the steel cords is required to maintain its adhesion to the steel cords even when exposed to severe heat or humid heat environments.

[0003] Patent Document 1 discloses a rubber composition comprising diene rubber, cobalt benzoate, cobalt(II) acetylacetonate and / or cobalt(III) acetylacetonate, and rosin.

[0004] Patent Document 2 discloses a rubber composition for metal bonding, comprising a diene rubber, an amine-based antioxidant, a phenol-based antioxidant, and liquid rubber.

[0005] Patent Document 3 is a technology provided by the present applicant and discloses a tear strength imparting agent for rubber containing a pyrazolone compound. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2007-99868 [Patent Document 2] Japanese Patent Publication No. 2021-84946 [Patent Document 3] Japanese Patent Publication No. 2020-33454 [Overview of the project] [Problems that the invention aims to solve]

[0007] The object of the present invention is to provide a rubber composition for metal bonding that has excellent hardness and metal adhesion properties.

[0008] Another object of the present invention is to provide a steel belt having excellent hardness and metal adhesion.

[0009] Another object of the present invention is to provide a pneumatic tire having a steel belt with excellent hardness and metal adhesion. [Means for solving the problem]

[0010] As a result of diligent research to solve the aforementioned problems, the inventors have found that a rubber composition obtained by blending a specific pyrazolone compound and a metal complex with a diene rubber has excellent hardness and metal adhesion.

[0011] In other words, the present invention provides the following rubber composition, steel belt, and pneumatic tire.

[0012] Section 1. A rubber composition for metal bonding, Diene rubbers, compounds represented by formulas (1) and (2), and at least one compound selected from salts of said compounds:

[0013] [ka]

[0014] (In formula (1), R 1 , R 2 , R 3 and R 4is the same as or different from, and represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group. R 3 and R 4 may be bonded to each other to form an alkylidene group, and R 2 , R 3 and R 4 any two of may be bonded to each other to form an alkylene group. Each of these groups may have one or more substituents. )

[0015] [Chemical formula]

[0016] (In formula (2), R 5 , R 7 and R 8 are the same as or different from each other, and represent a hydrogen atom, an amino group, an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group, and R 6 represents an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group. Each of these groups may have one or more substituents. ) and includes a metal complex, with respect to 100 parts by mass of the diene rubber, contains 0.1 to 5 parts by mass of at least one compound selected from the compounds represented by the above formulas (1) and (2) and salts of the compound, and contains 0.1 to 4 parts by mass of the metal complex, a rubber composition for metal adhesion.

[0017] Item 2. The metal of the metal complex is at least one metal selected from the group consisting of cobalt, iron, zinc, and aluminum, and the rubber composition for metal adhesion according to Item 1 above.

[0018] Item 3. The diene rubber contains 80 parts by mass or more of natural rubber and / or synthetic isoprene rubber in 100 parts by mass of the diene rubber component, and the rubber composition for metal adhesion according to Item 1 or 2 above.

[0019] Section 4. A rubber composition for metal bonding according to any one of the above items 1 to 3, for use with steel belts.

[0020] Section 5. A steel belt using the metal-bonding rubber composition described in item 4 above.

[0021] Section 6. A pneumatic tire using the steel belt described in item 5 above. [Effects of the Invention]

[0022] The present invention can provide a rubber composition for metal bonding that has excellent hardness and metal adhesion properties. [Modes for carrying out the invention]

[0023] The present invention will be described in detail below.

[0024] The embodiments illustrating the present invention are intended to provide a better understanding of the invention's intent and, unless otherwise specified, do not limit the scope of the invention.

[0025] In this specification, "contains" and "include" are concepts that encompass all of the following: "comprise," "consist essentially of," and "consist of."

[0026] In this specification, when a numerical range is indicated as "A to B", the numerical range means A or greater and B or less.

[0027] 1. Rubber composition for metal bonding The present invention relates to a rubber composition for metal bonding comprising at least one compound selected from diene rubber, compounds represented by formulas (1) and (2), and salts of said compounds:

[0028] [ka]

[0029] (In formula (1), R 1 , R 2 , R 3 and R 4 R represents the same or different hydrogen atom, alkyl group, aralkyl group, aryl group, or heterocyclic group. 3 and R 4 These may bond with each other to form an alkylidene group, R 2 , R 3 and R 4 Any two of these groups may bond to each other to form an alkylene group. Each of these groups may have one or more substituents.

[0030] [ka]

[0031] (In formula (2), R 5 , R 7 and R 8 R represents the same or different hydrogen atom, amino group, alkyl group, aralkyl group, aryl group, or heterocyclic group, and R 6 (This represents an alkyl group, aralkyl group, aryl group, or heterocyclic group. Each of these groups may have one or more substituents.) Furthermore, the material contains a metal complex, comprising 0.1 to 5 parts by mass of at least one compound selected from the compounds represented by formulas (1) and (2) and salts thereof, and 0.1 to 4 parts by mass of the metal complex, per 100 parts by mass of the diene rubber.

[0032] The rubber composition for metal bonding of the present invention has sufficient hardness and good adhesion (metal adhesion) to metal reinforcing cords. In particular, the rubber-metal adhesion of the rubber composition of the present invention remains good even after being exposed to moist heat for a long period of time (after aging).

[0033] 1-1. Diene-based rubber The rubber composition for metal bonding of the present invention includes a diene-based rubber.

[0034] The diene rubber preferably contains 80 parts by mass or more of natural rubber and / or synthetic isoprene rubber per 100 parts by mass of the diene rubber component.

[0035] Examples of diene rubbers of the present invention include natural rubber, synthetic isoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), nitrile rubber (NBR), chloroprene rubber (CR), ethylene-propylene-diene terpolymer rubber (EPDM), styrene-isoprene-styrene terpolymer block copolymer (SIS), styrene-butadiene-styrene terpolymer block copolymer (SBS), and modified synthetic diene rubbers thereof. Modified synthetic diene rubbers include diene rubbers modified by modification methods such as main chain modification, one-end modification, and both-end modification. Here, examples of modified functional groups in modified synthetic diene rubbers include epoxy groups, amino groups, alkoxysilyl groups, hydroxyl groups, and other functional groups, and one or more of these functional groups may be included in the modified synthetic diene rubber.

[0036] Examples of the above-mentioned natural rubbers include natural rubber latex, technically graded rubber (TSR), smoked sheet (RSS), gutta-percha, natural rubber derived from Eucommia ulmoides, natural rubber derived from guayule, and natural rubber derived from Russian dandelion. Furthermore, modified natural rubbers obtained by modifying these natural rubbers, such as epoxidized natural rubber, methacrylic acid modified natural rubber, halogen-modified natural rubber, deproteinized natural rubber, maleic acid modified natural rubber, sulfonic acid modified natural rubber, and styrene-modified natural rubber, are also included in the natural rubbers of the present invention.

[0037] There are no particular limitations on the manufacturing method of diene rubber, and examples include emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, and cationic polymerization. Furthermore, there are no particular limitations on the glass transition temperature of the diene rubber.

[0038] There are no particular restrictions on the cis / trans / vinyl ratio of the double bond in the diene rubber; any ratio can be suitably used. Furthermore, there are no particular restrictions on the number-average molecular weight and molecular weight distribution of the diene rubber, but a number-average molecular weight of 500 to 3,000,000 and a molecular weight distribution of 1.5 to 15 are preferred.

[0039] Diene-based rubbers can be used individually or in mixtures (blends) of two or more types.

[0040] Among these, preferred forms include natural rubber alone, synthetic isoprene rubber alone, a mixture of natural rubber and synthetic isoprene rubber, a mixture of natural rubber and other diene-based rubbers, a mixture of synthetic isoprene rubber and other diene-based rubbers, and a mixture of natural rubber, synthetic isoprene rubber and other diene-based rubbers. More preferred forms include natural rubber alone, synthetic isoprene rubber alone, a mixture of natural rubber and synthetic isoprene rubber, and a mixture of natural rubber, synthetic isoprene rubber and other diene-based rubbers (where at least 80 parts by mass of natural rubber and synthetic isoprene rubber are present in 100 parts by mass of diene-based rubber). A particularly preferred form is where at least 90 parts by mass of natural rubber and synthetic isoprene rubber are present in 100 parts by mass of diene-based rubber.

[0041] In the metal-bonding rubber composition of the present invention, by adjusting the composition of the diene-based rubber component to the aforementioned range, the metal-bonding rubber composition can exhibit excellent elasticity, reduce the cost of the metal-bonding rubber composition, and consequently improve economic efficiency.

[0042] 1-2. At least one compound selected from the compounds represented by formulas (1) and (2), and salts thereof. The metal-bonding rubber composition of the present invention contains, with respect to 100 parts by mass of the diene rubber, 0.1 to 5 parts by mass of at least one compound selected from the compounds represented by formulas (1) and (2), and salts of said compounds (hereinafter collectively referred to as "pyrazolone derivatives").

[0043] In the rubber composition for metal bonding of the present invention, by blending a pyrazolone derivative and a metal complex with a diene-based rubber component, the pyrazolone derivative present in the diene-based rubber component forms a chelate complex with the copper, zinc, or other plating layer on the surface of the steel cord, thereby enabling stabilization of the rubber-metal surface layer during deterioration due to moist heat.

[0044] The rubber composition for metal bonding of the present invention exhibits excellent hardness and metal adhesion (adhesion to metal reinforcing cords).

[0045] The compound represented by formula (1) of the present invention, and the salt of said compound, are compounds represented by the following formula (1).

[0046] Hereinafter, the compound and its salt will be collectively referred to simply as compound (1).

[0047] [ka]

[0048] In formula (1), R 1 , R 2 , R 3 and R 4 These are identical or distinct and represent a hydrogen atom, alkyl group, aralkyl group, aryl group, or heterocyclic group.

[0049] In formula (1), R 3 and R 4 These may bond with each other to form an alkylidene group, R 2 , R 3 and R 4 Any two of these may bond with each other to form an alkylene group.

[0050] In formula (1), each of these groups may have one or more substituents.

[0051] The compound represented by formula (2) of the present invention, and the salt of said compound, are compounds represented by the following formula (2).

[0052] Hereinafter, the compound and its salt will be collectively referred to simply as compound (2).

[0053] [ka]

[0054] In formula (2), R 5 , R 7 and R 8 R represents the same or different hydrogen atom, amino group, alkyl group, aralkyl group, aryl group, or heterocyclic group, and R 6 This represents an alkyl group, aralkyl group, aryl group, or heterocyclic group.

[0055] In formula (2), each of these groups may have one or more substituents.

[0056] In compound (1) or (2), the "alkyl group" is not particularly limited and includes, for example, linear, branched, or cyclic alkyl groups. Specifically, examples include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, and t-butyl. Furthermore, examples include 1-ethylpropyl, n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl, and 3-methylpropyl. Examples include linear or branched alkyl groups having 5 to 18 carbon atoms, such as ntyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, 5-propylnonyl, n-tridecyl, n-tetradecyl, n-pentadecyl, hexadecyl, heptadecyl, and octadecyl; and cyclic alkyl groups having 3 to 8 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

[0057] In compound (1) or (2), the "aralkyl group" is not particularly limited and examples include benzyl, phenethyl, trityl, 1-naphthylmethyl, 2-(1-naphthyl)ethyl, and 2-(2-naphthyl)ethyl groups.

[0058] In compound (1) or (2), the "aryl group" is not particularly limited and examples include phenyl, biphenyl, naphthyl, dihydroindenyl, and 9H-fluorenyl groups.

[0059] In compound (1) or (2), there are no particular limitations on the "heterocyclic group," for example, 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), 6-(1,2,4-triazyl), 2-quinolyl, 3-quinolyl, 4-quinolyl, 5-quinolyl, 6-quinolyl, 7-quinolyl, 8-quinolyl Ryl, 1-isoquinoryl, 3-isoquinoryl, 4-isoquinoryl, 5-isoquinoryl, 6-isoquinoryl, 7-isoquinoryl, 8-isoquinoryl, 2-quinoxalyl, 3-quinoxalyl, 5-quinoxalyl, 6-quinoxalyl, 7-quinoxalyl, 8-quinoxalyl, 3-sinnoryl, 4-sinnoryl, 5-sinnoryl, 6-sinnoryl, 7-sinnoryl, 8-sinnoryl, 2-quinazolyl, 4-quinazolyl, 5-quinazolyl, 6-quinazolyl, 7-quinazolyl, 8-quinazolyl, 1-phthaladyl, 4-phthaladyl, 5-phthaladyl, 6-phthaladyl, 7- Phthalazyl, 8-Phthalazyl, 1-Tetrahydroquinolyl, 2-Tetrahydroquinolyl, 3-Tetrahydroquinolyl, 4-Tetrahydroquinolyl, 5-Tetrahydroquinolyl, 6-Tetrahydroquinolyl, 7-Tetrahydroquinolyl, 8-Tetrahydroquinolyl, 1-Pyrrolyl, 2-Pyrrolyl, 3-Pyrrolyl, 2-Furyl, 3-Furyl, 2-Thenyl, 3-Thenyl, 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, 5-isothiazolyl, 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), 5-(1,2,4-Triazolyl), 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, 7-Benzimidazolyl, 2-Benzofuranil, 3-Benzofuranil, 4-Benzofuranil, 5-Benzofuranil, 6-Benzofuranil, 7-Benzofuranil, 1-Isobenzofuranil, 3-Isobenzofuranil, 4-Isobenzofuranil, 5-Isobenzofuranil, 6-Isobenzofuranil, 7-Isobenzofuranil, 2-Benzotienyl, 3-Benzothienyl Nyl, 4-benzothienyl, 5-benzothienyl, 6-benzothienyl, 7-benzothienyl, 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-piperazolyl Examples include dil, 1-piperidyl, 2-piperidyl, 3-piperidyl, 4-piperidyl, 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, 5-methyl-3-oxo-2,3-dihydro-1H-pyrazole-4-yl group, morpholino group, etc.

[0060] In compound (1) or (2), the "alkylene group" is not particularly limited and can be any alkylene group having 2 to 7 carbon atoms, such as an ethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, or heptamethylene group. These alkylene groups may contain nitrogen, oxygen, or sulfur atoms, and may also be mediated by a phenylene group. Examples of such alkylene groups include -CH2NHCH2-, -CH2NHCH2CH2-, -CH2NHNHCH2-, -CH2CH2NHCH2CH2-, -CH2NHNHCH2NHCH2-, -CH2CH2CH2NHCH2CH2-, -CH2OCH2CH2-, -CH2CH2OCH2CH2-, -CH2SCH2CH2-, -CH2CH2SCH2CH2-,

[0061] [ka]

[0062] These are some examples.

[0063] In compound (1) or (2), the "alkylidene group" has approximately 1 to 4 carbon atoms and is not particularly limited; examples include methylidene, ethylidene, propyridene, isopropylidene, and butyridene groups.

[0064] These alkyl groups, aralkyl groups, aryl groups, heterocyclic groups, and alkylene groups may each have one or more substituents at any substituted position.

[0065] The "substituent" is not particularly limited and includes, for example, halogen atoms, amino groups, aminoalkyl groups, alkoxycarbonyl groups, acyl groups, acyloxy groups, amide groups, carboxyl groups, carboxyalkyl groups, formyl groups, nitrile groups, nitro groups, alkyl groups, hydroxyalkyl groups, hydroxyl groups, alkoxy groups, aryl groups, aryloxy groups, heterocyclic groups, thiol groups, alkylthio groups, arylthio groups, and the like.

[0066] The substituent may preferably consist of 1 to 5 individuals, and more preferably 1 to 3 individuals.

[0067] In compound (1) or (2), the "halogen atom" may be a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and preferably a chlorine atom, a bromine atom, or an iodine atom.

[0068] In compound (1) or (2), the "amino group" includes not only amino groups represented by -NH2, but also substituted amino groups such as linear or branched monoalkylamino groups having approximately 1 to 6 carbon atoms, such as methylamino, ethylamino, n-propylamino, isopropylamino, n-butylamino, isobutylamino, s-butylamino, t-butylamino, 1-ethylpropylamino, n-pentylamino, neopentylamino, n-hexylamino, isohexylamino, and 3-methylpentylamino; and dialkylamino groups having two linear or branched alkyl groups having approximately 1 to 2 carbon atoms, such as dimethylamino, ethylmethylamino, and diethylamino.

[0069] In compound (1) or (2), there are no particular limitations on the "aminoalkyl group," and examples include aminoalkyl groups having approximately 1 to 7 carbon atoms, such as aminomethyl, methylaminomethyl, ethylaminomethyl, dimethylaminomethyl, ethylmethylaminomethyl, diethylaminomethyl, 2-aminoethyl, 2-(methylamino)ethyl, 2-(ethylamino)ethyl, 2-(dimethylamino)ethyl, 2-(ethylmethylamino)ethyl, 2-(diethylamino)ethyl, 3-aminopropyl, 3-(methylamino)propyl, 3-(ethylamino)propyl, 3-(dimethylamino)propyl, 3-(ethylmethylamino)propyl, and 3-(diethylamino)propyl groups, as well as monoalkyl-substituted aminoalkyl groups or dialkyl-substituted aminoalkyl groups.

[0070] In compound (1) or (2), the "alkoxycarbonyl group" is not particularly limited and includes, for example, linear or branched alkoxycarbonyl groups having 1 to 4 carbon atoms, such as methoxycarbonyl and ethoxycarbonyl groups.

[0071] In compound (1) or (2), the "acyl group" is not particularly limited and includes, for example, linear or branched alkylcarbonyl groups having 1 to 4 carbon atoms, such as acetyl, propionyl, and pivaloyl groups.

[0072] In compound (1) or (2), the "acyloxy group" is not particularly limited and includes, for example, linear or branched acyloxy groups having 1 to 4 carbon atoms, such as acetyloxy, propionyloxy, and n-butyryloxy groups.

[0073] In compound (1) or (2), the "amide group" is not particularly limited and includes, for example, carboxylic acid amide groups such as acetamide and benzamide; thioamide groups such as thioacetamide and thiobenzamide; N-substituted amide groups such as N-methylacetamide and N-benzylacetamide; and the like.

[0074] In compound (1) or (2), the "carboxyalkyl group" is not particularly limited and examples include carboxyalkyl groups such as carboxymethyl, carboxyethyl, carboxy-n-propyl, carboxy-n-butyl, carboxy-n-pentyl, and carboxy-n-hexyl groups.

[0075] In compound (1) or (2), the "hydroxyalkyl group" is not particularly limited and examples include hydroxyalkyl groups such as hydroxymethyl, hydroxyethyl, hydroxy-n-propyl, and hydroxy-n-butyl.

[0076] In compound (1) or (2), the "alkoxy group" is not particularly limited and includes, for example, linear, branched, or cyclic alkoxy groups. Specifically, examples include linear or branched alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, t-butoxy, n-pentyloxy, neopentyloxy, and n-hexyloxy groups; and cyclic alkoxy groups such as cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, cycloheptyloxy, and cyclooctyloxy groups.

[0077] In compound (1) or (2), the "aryloxy group" is not particularly limited and examples include phenoxy, biphenyloxy, naphthoxy, etc.

[0078] In compound (1) or (2), the "alkylthio group" is not particularly limited and examples include a methylthio group, an ethylthio group, and an n-propylthio group.

[0079] In compound (1) or (2), the "arylthio group" is not particularly limited and examples include a phenylthio group, a naphthylthio group, a biphenylthio group, etc.

[0080] Among compound (1), R 1 Compounds in which the atom is a hydrogen atom are preferred.

[0081] Among compound (1), R 2 However, compounds comprising a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, an aralkyl group, an aryl group, or a heterocyclic group are preferred, compounds comprising a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a benzyl group, a phenyl group, a naphthyl group, or a furyl group are more preferred, and compounds comprising a hydrogen atom or a linear alkyl group having 1 to 4 carbon atoms are even more preferred.

[0082] Among compound (1), R 3 and R 4 A compound in which at least one of the atoms is a hydrogen atom is preferred, R 3 and R 4 Compounds in which both atoms are hydrogen atoms are more preferable.

[0083] Among compound (1), R 1 is a hydrogen atom, and R 2 R is a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, an aralkyl group, an aryl group, or a heterocyclic group. 3 and R 4 Compounds in which both are hydrogen atoms, and R 1 is a hydrogen atom, and R 2 R is a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, an aralkyl group, an aryl group, or a heterocyclic group. 3 and R 4 A compound in which these together form an alkylidene group is even more preferred, R 1 is a hydrogen atom, and R 2 R is a hydrogen atom or a linear alkyl group having 1 to 4 carbon atoms, 3 and R 4 Compounds in which both atoms are hydrogen atoms are particularly preferred.

[0084] Among compound (2), R 5 R is a hydrogen atom, 6 R is a linear or branched alkyl group, aralkyl group, or aryl group having 1 to 4 carbon atoms. 7 and R 8The compounds are preferably the same or different, and each compound is a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, an aralkyl group, an aryl group, an amino group, or a heterocyclic group.

[0085] Among compound (2), R 6 Compounds in which the group is a linear alkyl group, aralkyl group, or aryl group having 1 to 4 carbon atoms are preferred, and compounds in which the group is a linear alkyl group or aryl group having 1 to 4 carbon atoms are more preferred.

[0086] Among compound (2), R 7 and R 8 Compounds in which the same or different atoms are a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, or an amino group are preferred.

[0087] Among compound (2), R 5 R is a hydrogen atom, 6 R is a linear alkyl group or aryl group having 1 to 4 carbon atoms, 7 and R 8 Compounds in which the same or different atoms are a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, or an amino group are preferred.

[0088] Of compound (1) and compound (2), compound (1) is particularly preferred.

[0089] Examples of compound (1) include 5-pyrazolone, 3-methyl-5-pyrazolone, 3-(naphthalene-2-yl)-1H-pyrazole-5(4H)-one, 3-(furan-2-yl)-1H-pyrazole-5(4H)-one, 3-phenyl-1H-pyrazole-5(4H)-one, 3-propyl-1H-pyrazole-5(4H)-one, and 3-t-butyl-1H-pyrazole-5(4 H)-one, 3-undecyl-1H-pyrazole-5(4H)-one, 4-(2-hydroxyethyl)-3-methyl-1H-pyrazole-5(4H)-one, 4-benzyl-3-methyl-1H-pyrazole-5(4H)-one, 4,4'-(phenylmethylene)bis(5-methyl-1H-pyrazole-3(2H)-one), 4-[(dimethylamino)methylidene]-3-methyl-1H -Pyrazole-5(4H)-one, 4-methyl-2,3-diazospiro[4.4]non-3en-1-one, 5-methyl-2-(4-nitrophenyl)-1H-pyrazole-3(2H)-one, 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazole-3-one, 4,5,6,7-tetrahydro-2H-indazole-3(3aH)-one, 4-{[4-dimethylamino Examples include phenyl}methylidene}-3-methyl-1H-pyrazole-5(4H)-one, 4,4'-(4-hydroxyphenylmethylene)bis(5-methyl-1H-pyrazole-3(2H)-one), 1,3-diphenyl-1H-pyrazole-5(4H)-one, and 4,4'-(4-nitrophenylmethylene)bis(5-methyl-1H-pyrazole-3(2H)-one).

[0090] Examples of compound (2) include 1,5-dimethyl-2-phenyl-1H-pyrazole-3(2H)-one, 1-phenyl-1H-pyrazole-3(2H)-one, and 4-amino-1,5-dimethyl-2-phenyl-1H-pyrazole-3(2H)-one.

[0091] Among these, preferred compounds are 5-pyrazolone, 3-methyl-5-pyrazolone, 3-t-butyl-1H-pyrazole-5(4H)-one, 3-(naphthalene-2-yl)-1H-pyrazole-5(4H)-one, 3-(furan-2-yl)-1H-pyrazole-5(4H)-one, 3-phenyl-1H-pyrazole-5(4H)-one, and 3-propyl-1H-pyrazole-5(4H)-one, which are more preferred.

[0092] The compounds (1) and (2) contained in the rubber composition of the present invention may consist of only one of the above-mentioned compounds alone, or they may consist of a mixture of two or more compounds.

[0093] Some compounds (1) or (2) produce tautomers. If tautomerization is possible (e.g., in solution), a chemical equilibrium of tautomers can be reached. Compounds (1) or (2) can exist as tautomers represented, for example, by formulas (3) to (9).

[0094] In the above equation (1), R 1 and R 3 Compounds in which the atom is a hydrogen atom (compound (1)-A) have tautomers represented by the following formulas (3) to (5).

[0095] [ka]

[0096] (In the formula, R 2 and R 4 (The same applies as above.) In the above equation (1), R 3 Compounds in which the atom is a hydrogen atom (compound (1)-B) have tautomers represented by the following formulas (6) to (7).

[0097] [ka]

[0098] (In the formula, R1 , R 2 and R 4 (The same applies as above.) In the above equation (1), R 1 For compounds in which the atom is a hydrogen atom (compound (1)-C), there exists a tautomer represented by the following formula (8).

[0099] [ka]

[0100] (In the formula, R 2 , R 3 and R 4 (The same applies as above.) In equation (2) above, R 5 For compounds in which the atom is a hydrogen atom (compound (2)-A), there exists a tautomer represented by the following formula (9).

[0101] [ka]

[0102] Compound (1) or (2) and the tautomers represented by formulas (3) to (9) above have reached an equilibrium state in which both isomers coexist. Therefore, unless otherwise stated, all forms of tautomers of compound (1) or (2) are within the scope of the present invention.

[0103] The salts of the compounds represented by formula (1) or (2) are not particularly limited and include all kinds of salts. Examples of such salts include inorganic salts such as hydrochloride, sulfate, and nitrate; organic salts such as acetate and methanesulfonate; alkali metal salts such as sodium and potassium salts; alkaline earth metal salts such as magnesium and calcium salts; and ammonium salts such as dimethylammonium and triethylammonium.

[0104] The amount of compound (1) or (2) blended is 0.1 to 5 parts by mass, preferably 0.2 to 5.0 parts by mass, more preferably 0.2 to 2.0 parts by mass, and even more preferably 0.3 to 1.0 parts by mass, per 100 parts by mass of the diene rubber in the metal adhesive rubber composition.

[0105] In the metal-bonding rubber composition of the present invention, by adjusting the amount of compound (1) or (2) within the above range, the metal-bonding rubber composition can exhibit excellent hardness and metal-bonding properties.

[0106] 1-3. Metal Complexes The rubber composition for metal bonding of the present invention contains 0.1 to 4 parts by mass of a metal complex per 100 parts by mass of the diene rubber.

[0107] The metal in the aforementioned metal complex is preferably at least one metal selected from the group consisting of cobalt, iron, zinc, and aluminum.

[0108] In the rubber composition for metal bonding of the present invention, by blending a pyrazolone derivative and a metal complex with a diene-based rubber component, the pyrazolone derivative present in the diene-based rubber component forms a chelate complex with the copper, zinc, or other plating layer on the surface of the steel cord, thereby enabling stabilization of the rubber-metal surface layer during deterioration due to moist heat.

[0109] The rubber composition for metal bonding of the present invention exhibits excellent hardness and metal adhesion (adhesion to metal reinforcing cords).

[0110] The metal in the metal complex of the present invention is not particularly limited, but is a metal whose central metal is an element belonging to groups 7 to 14 of the periodic table, and is preferably cobalt, iron, zinc, aluminum, copper, or tin, more preferably cobalt, iron, zinc, nickel, or aluminum, and particularly preferably cobalt. The metal in the metal complex may be uncharged or charged ions.

[0111] The ligands of the metal complex of the present invention are not particularly limited, but are preferably stearic acid, naphthenic acid, neodecanoic acid, oleic acid, resinic acid, rosinic acid, versatic acid, tall oil, boric acid, neodecanoic acid, acetylacetonate, etc.

[0112] Examples of organic cobalt acid salts include cobalt naphthenate, cobalt neodecanoate, cobalt stearate, cobalt oleate, cobalt resinate, cobalt rosinate, cobalt versatate, cobalt tollate, cobalt neodecanoate borate, and cobalt acetylacetonate. Examples of iron metal complex compounds include iron pentacarbonyl, iron nonacarbonyl, and sodium tetracarbonylferric acid. Examples of zinc metal complex compounds include tetraamminezinc.

[0113] Among the metal complex compounds, cobalt stearate and cobalt naphthenate are preferred, and cobalt stearate is particularly preferred.

[0114] The amount of the above metal complex added is 0.1 to 4 parts by mass, preferably 0.1 to 4.0 parts by mass, more preferably 0.5 to 3.5 parts by mass, and even more preferably 1.0 to 3.0 parts by mass, per 100 parts by mass of the above diene rubber in the metal adhesive rubber composition.

[0115] In the rubber composition for metal bonding of the present invention, by adjusting the amount of the above-mentioned metal complex to within the above-mentioned range, the rubber composition for metal bonding can exhibit excellent hardness and metal bonding properties.

[0116] 1-4. Other compounding agents In addition to the components mentioned above, the rubber composition for metal bonding of the present invention may also contain, in appropriate selection and in moderation, compounding agents commonly used in the rubber industry, such as carbon black, inorganic fillers, antioxidants, ozone inhibitors, softeners, processing aids, waxes, liquid rubber, foaming agents, oils, fatty acids with 8 to 30 carbon atoms such as stearic acid, zinc oxide (ZnO, zinc oxide), vulcanization accelerators, vulcanization retarders, and vulcanizing agents (sulfur), as long as they do not impair the purpose of the present invention. These compounding agents can be widely used from those known to be used in rubber compositions for tires; for example, commercially available products can be suitably used.

[0117] Carbon black is typically used to improve the reinforcing properties of rubber. However, in this specification, inorganic fillers do not contain carbon black.

[0118] There are no particular restrictions on the type of carbon black used; for example, commercially available carbon black or carbon-silica dual phase filler can be used. By incorporating carbon black into the rubber component, it is possible to reduce the electrical resistance of the rubber, thereby suppressing static charge buildup, and also improve the strength of the rubber.

[0119] Specifically, examples of carbon black include high, medium, or low structure carbon blacks of SAF, ISAF, IISAF, N110, N134, N220, N234, N330, N339, N375, N550, HAF, FEF, GPF, and SRF grades. Among these, preferred carbon blacks are SAF, ISAF, IISAF, N134, N234, N330, N339, N375, HAF, or FEF grade carbon blacks.

[0120] There are no particular restrictions on the amount of DBP absorbed by carbon black, but preferably 60 cm³. 3 / 100g~200cm 3 / 100g, comfortably 70cm 3 / 100g~180cm 3 / 100g, especially preferably 80cm 3 / 100 g to 160 cm 3 It is / 100 g.

[0121] Also, the nitrogen adsorption specific surface area (N2SA, measured in accordance with JIS K6217-2:2001) of the carbon black is preferably 30 m 2 / g to 200 m 2 / g, more preferably 40 m 2 / g to 180 m 2 / g, particularly preferably 50 m 2 / g to 160 m 2 / g.

[0122] The inorganic filler (inorganic compound) is not particularly limited. For example, silica; alumina (Al2O3) such as γ-alumina and α-alumina; alumina monohydrate (Al2O3·H2O) such as boehmite and diaspore; aluminum hydroxide [Al(OH)3] such as gibbsite and bayerite; 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], magnesium aluminum 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.), calcium aluminum silicate (Al₂O₃·CaO·2SiO₂, etc.), calcium magnesium silicate (CaMgSiO₄), calcium carbonate (CaCO₃), zirconium oxide (ZrO₂), zirconium hydroxide [ZrO(OH)₂·nH₂O], zirconium carbonate [Zr(CO₃)₂], zinc acrylate, zinc methacrylate, crystalline aluminosilicates containing hydrogen, alkali metals or alkaline earth metals for charge correction such as various zeolites, etc. can be mentioned.

[0123] In order to improve the affinity with the polymer material, the surface of these inorganic fillers may be organically treated.

[0124] As the silica, any commercially available one can be used. Among them, preferred silica is wet silica, dry silica, or colloidal silica, and more preferably wet silica. In order to improve the affinity with the rubber component, the surface of these silica may be organically treated.

[0125] The BET specific surface area of the silica is not particularly limited. For example, it may be in the range of 40 m 2 / g to 350 m 2 / g. Silica with a BET specific surface area in this range has the advantage of being able to achieve good dispersibility in the polymer material. The BET specific surface area is measured in accordance with ISO5794 / 1.

[0126] Preferred silica has a BET specific surface area of 80 m 2 / g to 300 m 2Silica in the range of / g, more preferably with a BET specific surface area of ​​100m². 2 / g~270m 2 The silica is of a certain weight ( / g), and is particularly preferably a BET specific surface area of ​​110 m². 2 / g~260m 2 This silica is within the range of / g.

[0127] A commercially available silica product is "HD165MP" manufactured by Quechen Silicon Chemical Co., Ltd. (BET specific surface area = 165 m²). 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), product name "NipSeal AQ" manufactured by Tosoh Silica Co., Ltd. (BET specific surface area = 205m²) 2 / g), "NipSeal KQ" (BET specific surface area = 240m²) 2 / g), Degussa's product name "UltraZil VN3" (BET specific surface area = 175m²) 2 Examples include / g).

[0128] The amount of carbon black and / or inorganic filler added is not particularly limited, but is typically 10 to 120 parts by mass, preferably 30 to 80 parts by mass, and more preferably 35 to 70 parts by mass, per 100 parts by mass of diene rubber.

[0129] When incorporating both carbon black and inorganic fillers, the total amount of both components should be adjusted as appropriate so that it falls within the above range.

[0130] If the amount of carbon black and / or inorganic filler is 10 parts by mass or more, it is preferable from the viewpoint of improving the reinforcing properties of the metal adhesive rubber composition, and if it is 120 parts by mass or less, it is preferable from the viewpoint of the processability of the metal adhesive rubber composition.

[0131] The amount of carbon black added is typically 20 to 100 parts by mass, preferably 35 to 80 parts by mass, and more preferably 40 to 70 parts by mass, per 100 parts by mass of diene rubber.

[0132] If the amount of carbon black is 20 parts by mass or more, it is preferable from the viewpoint of ensuring antistatic performance and rubber strength performance, and if it is 100 parts by mass or less, it is preferable from the viewpoint of rubber hardness.

[0133] The amount of inorganic filler (such as silica) added is typically 10 to 50 parts by mass per 100 parts by mass of diene rubber.

[0134] The amount of silica added is typically 2 to 100 parts by mass, preferably 30 to 80 parts by mass, and more preferably 35 to 60 parts by mass, per 100 parts by mass of diene rubber.

[0135] When incorporating carbon black and / or inorganic fillers (such as silica), silane coupling agents, titanate coupling agents, aluminate coupling agents, and zirconate coupling agents may be added for purposes such as increasing the strength of the polymer material due to the carbon black and / or inorganic fillers.

[0136] The silane coupling agent is not particularly limited, and examples include sulfide-based, polysulfide-based, thioester-based, thiol-based, olefin-based, epoxy-based, amino-based, and alkyl-based silane coupling agents.

[0137] Examples of sulfide-based silane coupling agents include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(3-methyldimethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-triethoxysilylpropyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(3-methyldimethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(3-trimethoxysilylpropyl) trisulfide, and bis(3-methyldimethoxysilylpropyl Examples include trisulfide, bis(2-triethoxysilylethyl) trisulfide, bis(3-monoethoxydimethylsilylpropyl) tetrasulfide, bis(3-monoethoxydimethylsilylpropyl) trisulfide, bis(3-monoethoxydimethylsilylpropyl) disulfide, bis(3-monomethoxydimethylsilylpropyl) tetrasulfide, bis(3-monomethoxydimethylsilylpropyl) trisulfide, bis(3-monomethoxydimethylsilylpropyl) disulfide, bis(2-monoethoxydimethylsilylethyl) tetrasulfide, bis(2-monoethoxydimethylsilylethyl) trisulfide, and bis(2-monoethoxydimethylsilylethyl) disulfide. Of these, bis(3-triethoxysilylpropyl) tetrasulfide is particularly preferred.

[0138] Examples of thioester-based silane coupling agents include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, and 2-lauroylthioethyltrimethoxysilane.

[0139] Examples of thiol-based silane coupling agents include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-[ethoxybis(3,6,9,12,15-pentaoxacosan-1-yloxy)silyl]-1-propanethol.

[0140] Examples of olefin-based silane coupling agents include dimethoxymethylvinylsilane, vinyltrimethoxysilane, dimethylethoxyvinylsilane, diethoxymethylvinylsilane, triethoxyvinylsilane, vinyltris(2-methoxyethoxy)silane, allyltrimethoxysilane, allyltriethoxysilane, p-styryltrimethoxysilane, 3-(methoxydimethoxydimethylsilyl)propyl acrylate, 3-(trimethoxysilyl)propyl acrylate, 3-[dimethoxy(methyl)silyl]propyl methacrylate, 3-(trimethoxysilyl)propyl methacrylate, 3-[dimethoxy(methyl)silyl]propyl methacrylate, 3-(triethoxysilyl)propyl methacrylate, and 3-[tris(trimethylsiloxy)silyl]propyl methacrylate.

[0141] Examples of epoxy-based silane coupling agents include 3-glycidyloxypropyl(dimethoxy)methylsilane, 3-glycidyloxypropyltrimethoxysilane, diethoxy(3-glycidyloxypropyl)methylsilane, triethoxy(3-glycidyloxypropyl)silane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Of these, 3-glycidyloxypropyltrimethoxysilane is preferred.

[0142] Examples of amino-based silane coupling agents include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-ethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane. Of these, 3-aminopropyltriethoxysilane is preferred.

[0143] Examples of alkyl-based silane coupling agents include methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, cyclohexylmethyldimethoxysilane, n-octyltriethoxysilane, and n-decyltrimethoxysilane. Of these, methyltriethoxysilane is preferred.

[0144] Among these silane coupling agents, bis(3-triethoxysilylpropyl)tetrasulfide is particularly preferred.

[0145] The titanate coupling agent is not particularly limited, and examples include alkoxide, chelate, and acylate type titanate coupling agents.

[0146] Examples of alkoxide-based titanate coupling agents include tetraisopropyl titanate, tetran-butyl titanate, butyl titanate dimer, tetraoctyl titanate, tetratert-butyl titanate, and tetrastearyl titanate. Of these, tetraisopropyl titanate is preferred.

[0147] Examples of chelate-type titanate coupling agents include titanium acetylacetonate, titanium tetraacetylacetonate, titanium ethylacetoacetate, titanium dodecylbenzenesulfonate compounds, titanium phosphate compounds, titanium octylene glycolate, titanium ethylacetoacetate, titanium lactate ammonium salt, titanium lactate, titanium ethanolamine, titanium octylene glycolate, and titanium aminoethylaminoethanolate. Of these, titanium acetylacetonate is preferred.

[0148] Examples of acylate-based titanate coupling agents include titanium isostearate.

[0149] The aluminate coupling agent is not particularly limited, and examples of aluminate coupling agents include 9-octadecenylacetate aluminum diisopropylate, aluminum secondary butoxide, aluminum trisacetylacetonate, aluminum bisethylacetate monoacetylacetonate, and aluminum trisethylacetate. Of these, 9-octadecenylacetate aluminum diisopropylate is preferred.

[0150] The zirconate coupling agent is not particularly limited, and examples include alkoxide, chelate, and acylate-type zirconate coupling agents.

[0151] Examples of alkoxide-based zirconium coupling agents include n-propyl zirconate and n-butyl zirconate. Of these, n-butyl zirconate is preferred.

[0152] Examples of chelate-type zirconate coupling agents include zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium ethylacetoacetate, and zirconium lactate ammonium salt. Of these, zirconium tetraacetylacetonate is preferred.

[0153] Examples of acylate-type zirconate coupling agents include zirconium stearate and zirconium octoate. Of these, zirconium stearate is preferred.

[0154] In the present invention, the silane coupling agent, titanate coupling agent, aluminate coupling agent, and zirconate coupling agent may be used individually or in combination of two or more.

[0155] 1-5. Method for producing the rubber composition for metal bonding according to the present invention The metal-bonding rubber composition of the present invention can be produced by mixing the diene rubber, the pyrazolone compounds of compounds (1) and (2), and a metal complex. Other compounding agents may be mixed as needed. The order in which the diene rubber, the pyrazolone compounds of compounds (1) and (2), and the metal complex are mixed, and the order in which other compounding agents are added, can be set as appropriate.

[0156] In the present invention, the following manufacturing method can be used as a method for producing a rubber composition for metal bonding.

[0157] Manufacturing method 1 Step (A) is a step of mixing diene rubber, pyrazolone compounds of compounds (1) and (2), and raw material components including a metal complex, and Step (B) A step of mixing the mixture obtained in step (A) with a vulcanizing agent. A method that includes this.

[0158] Manufacturing method 2 Step (A) is a step of mixing diene rubber and raw material components containing the pyrazolone compounds of compounds (1) and (2), and, Step (B) A step of mixing the mixture obtained in step (A), the metal complex, and the vulcanizing agent. A method that includes this.

[0159] Manufacturing method 3 Process (A) A process of mixing raw material components including diene rubber and metal complexes, Step (B) is a step of mixing the mixture obtained in step (A), the pyrazolone compounds of compounds (1) and (2), and a vulcanizing agent. A method that includes this.

[0160] In the present invention, among the methods for producing a rubber composition for metal bonding, production method 1 is preferred.

[0161] 1-5-1. Process (A) Step (A) is a step of mixing raw material components including diene rubber, pyrazolone compounds of compounds (1) and (2), and a metal complex.

[0162] In step (A), other compounding agents as needed may be added.

[0163] In step (A), the raw material components, including diene rubber, pyrazolone compounds (1) and (2), and metal complexes, are mixed. In this mixing method, the entire amount of each component may be mixed at once, or each component may be added in portions and mixed according to the purpose of viscosity adjustment, etc. Alternatively, a filler masterbatch rubber in which the filler has been added to the rubber in advance by a wet method and / or a dry mixing method may be used.

[0164] There are no particular restrictions on the temperature when mixing the rubber composition in step (A). For example, the upper limit of the temperature of the rubber composition is preferably 100°C to 190°C, more preferably 110°C to 180°C, and even more preferably 120°C to 170°C.

[0165] There are no particular restrictions on the mixing time in step (A), but it is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and even more preferably 1 minute to 8 minutes.

[0166] 1-5-2. Process (B) Step (B) is the step of mixing the mixture obtained in step (A) with a vulcanizing agent.

[0167] In step (B), vulcanization accelerators and other additives may be added as needed.

[0168] Step (B) can be carried out under heating conditions. There are no particular restrictions on the heating temperature for this step, but for example, it is preferably 60°C to 140°C, more preferably 80°C to 120°C, and even more preferably 90°C to 120°C.

[0169] There are no particular restrictions on the mixing time; for example, it is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and even more preferably 60 seconds to 5 minutes.

[0170] When moving from process (A) to process (B), it is preferable to lower the temperature by 30°C or more from the temperature at the end of the previous process before proceeding to the next process (B).

[0171] In the method for producing the rubber composition for metal bonding according to the present invention, various compounding agents such as stearic acid, zinc oxide, and antioxidants, which are usually incorporated into rubber compositions, can be added in step (A) or step (B) as needed.

[0172] The above-mentioned compound may be added in either step (A) or step (B), or it may be added in both steps (A) and (B).

[0173] In this specification, "mixing" includes not only the act of simply mixing together, but also the act of so-called "kneading."

[0174] Mixing can be carried out either wet or dry using rotary ball mills, vibrating ball mills, planetary mills, paint shakers, rocking mills, rocking mixers, bead mills, fluidized bed mixers, agitators, etc. Mixing can also be carried out using Banbury mixers, rolls, intensive mixers, kneaders, single-screw extruders, twin-screw extruders, etc. After mixing, the mixture is processed and molded by extruding it in the extrusion process.

[0175] In the rubber composition for metal bonding of the present invention, the mixing operation may be repeated in order to uniformly disperse each component.

[0176] In the present invention, the rubber composition for metal bonding is bonded and molded on a molding machine, and then vulcanized by heating and pressurizing in a vulcanizing machine to obtain a vulcanized product.

[0177] 1-6. Uses of the rubber composition for metal bonding according to the present invention The rubber composition for metal bonding of the present invention is for metal bonding applications and can be used in applications such as steel belts, hoses, belt conveyor belts, and seismic isolation rubber equipped with metal reinforcing cords.

[0178] The rubber composition for metal bonding of the present invention exhibits good adhesion to metal reinforcing cords, and in tire applications, it can be suitably used, for example, as a rubber covering (steel belt) for a belt (steel cord) embedded in the undertread.

[0179] Steel cords that are brass-plated are preferable.

[0180] In addition to tire applications, the metal-bonding rubber composition of the present invention can also be suitably applied to, for example, hoses equipped with metal reinforcing cords and belts for belt conveyors.

[0181] In particular, the rubber composition of the present invention is preferred for use in steel belts.

[0182] 2. Steel belt The steel belt of the present invention is a steel belt manufactured using the metal bonding rubber composition of the present invention described above.

[0183] The rubber of the steel belt of the present invention may cover the steel on a uniform flat surface, or it may cover the steel with a certain shape, pattern, etc.

[0184] Furthermore, the steel belt of the present invention may consist of a single steel belt coated with the metal-adhesive rubber composition of the present invention, or it may consist of two or more steel belts coated with the metal-adhesive rubber composition.

[0185] The steel belt of the present invention has excellent hardness and metal adhesion.

[0186] 3. Pneumatic tires The pneumatic tire of the present invention is a tire manufactured using the steel belt of the present invention described above.

[0187] Examples of pneumatic tires of the present invention include radial tires and bias tires.

[0188] There are no particular restrictions on the use of the tire; examples include passenger car tires, heavy-duty tires, motorcycle tires, and studless tires. Among these, it is particularly suitable for use as a passenger car tire.

[0189] There are no particular limitations on the shape, structure, size, and material of the tire of the present invention, and they can be appropriately selected according to the purpose.

[0190] The tire of the present invention can be manufactured according to methods already known in the field of tires. Furthermore, as the gas used to fill the tire, ordinary air or air with adjusted oxygen partial pressure; or inert gases such as nitrogen, argon, or helium can be used.

[0191] This invention can provide a tire having a steel belt with excellent hardness and metal adhesion. [Examples]

[0192] The embodiments of the present invention will be described in more detail below based on the examples.

[0193] The present invention is not limited to these.

[0194] 1. Manufacturing of rubber compositions First, the diene rubber, 3-methyl-5-pyrazolone, cobalt stearate, etc., listed in Table 1 below were mixed in a plastomyl in their respective proportions. Next, a vulcanizing agent was added to the mixture to produce a rubber composition. The resulting rubber composition was vulcanized at 150°C for 30 minutes to obtain a vulcanized product.

[0195] 2.Hardness index Hardness was tested at room temperature in accordance with JIS K6253.

[0196] A vulcanized product of Comparative Example 1 was prepared, and its hardness value was expressed as an index with a base of 100. The hardness index of the vulcanized product of the Example was then calculated based on the following formula.

[0197] Hardness index = Hardness of example / Hardness of comparative example 1 × 100 A higher hardness index value for a vulcanized material indicates greater hardness and superior quality.

[0198] 3. Adhesion index after moist heat aging Adhesion after moist heat aging was tested in accordance with ASTM D-2229. Brass-plated steel cord was coated with the above vulcanized material, and adhesive samples were prepared by vulcanizing and bonding under vulcanization conditions of 160°C for 20 minutes.

[0199] This adhesive sample was aged under conditions of 70°C, 96% relative humidity, and for two weeks. Steel cords were pulled from this sample, and the amount of rubber adhering to them (%) was measured.

[0200] A vulcanized product of Comparative Example 1 was prepared, and the above test was performed. The value of the amount of rubber adhesion (%) was expressed as an index (adhesion index after moist heat aging) with the value set to 100, and the adhesion index after moist heat aging of the vulcanized product of the example was calculated based on the following formula.

[0201] Adhesion index after moist heat aging = Amount of rubber attached in Example 1 / Amount of rubber attached in Comparative Example 1 × 100 A higher wet heat aging adhesion index for a vulcanized material indicates better adhesion to rubber.

[0202] 4. Details of each ingredient *1: Natural rubber, TSR-20 *2: Carbon black, manufactured by Tokai Carbon Co., Ltd., Seast 300 *3: Anti-aging agent, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6-PPD) *4: Sulfurization accelerator, N-cyclohexyl-2-benzothiazole sulfenamide (CBS)

[0203] [Table 1]

[0204] The rubber composition for metal bonding of the present invention contains pyrazolone compounds such as 3-methyl-5-pyrazolone and metal complexes such as cobalt stearate. Compared to conventional rubber compositions, the resulting vulcanized product exhibited higher hardness and superior adhesion after degradation due to moist heat. [Industrial applicability]

[0205] The present invention relates to a rubber composition that uses pyrazolone compounds such as 3-methyl-5-pyrazolone and metal complexes such as cobalt stearate, and uses diene rubber such as natural rubber, which is widely used in bonding parts with metals. In this rubber composition, the hardness of the vulcanized product obtained from the rubber composition can be increased, and the adhesion (metal adhesion) to metal reinforcing cords after moist heat degradation can be improved.

[0206] The present invention provides a rubber composition for metal bonding that is useful for metal bonding applications, possesses sufficient hardness, and exhibits good metal bonding properties.

Claims

1. A rubber composition for metal bonding, comprising: At least one compound selected from diene rubbers, compounds represented by formulas (1) and (2), and salts of said compounds: 【Chemistry 1】 (In formula (1), R １ , R ２ , R ３ and R ４ R may be the same or different and represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group. ３ and R ４ may be bonded to each other to form an alkylidene group, R ２ , R ３ and R ４ Any two of the above may be bonded to each other to form an alkylene group. Each of these groups may have one or more substituents. 【Chemistry 2】 (In formula (2), R ５ , R ７ and R ８ are the same or different and each represents a hydrogen atom, an amino group, an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group; R ６ represents an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group. Each of these groups may have one or more substituents. and metal complexes, Relative to 100 parts by mass of the diene rubber, Contains 0.1 to 5 parts by mass of at least one compound selected from the compounds represented by formulas (1) and (2) and salts of said compounds, and The metal complex is present in an amount of 0.1 to 4 parts by mass. A rubber composition for bonding to metal.

2. 2. The rubber composition for metal bonding according to claim 1, wherein the metal of said metal complex is at least one metal selected from the group consisting of cobalt, iron, zinc, and aluminum.

3. 2. The rubber composition for metal bonding according to claim 1, wherein the diene rubber contains 80 parts by mass or more of natural rubber and / or synthetic isoprene rubber per 100 parts by mass of the diene rubber component.

4. The rubber composition for metal bonding according to any one of claims 1 to 3, which is for use in steel belts.

5. A steel belt using the rubber composition for bonding metal according to claim 4.

6. A pneumatic tire using the steel belt according to claim 5.

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