rubber composition

Abstract

To provide a rubber composition containing a zinc complex of hydrazide compound, and a tire made using the rubber composition.SOLUTION: A rubber composition contains a diene rubber component, a zinc complex of hydrazide compound, and a filler.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Large tires (especially extra-large tires used in mining) generally use natural rubber, which has excellent strength.

[0003] Due to the size of the tires, the vulcanization of large tires requires a long vulcanization time. For this reason, the vulcanization of large tires can cause a phenomenon called reversion, which is not a problem for small passenger car tires that are mainly made from synthetic rubber. This reversion can cause the polymer backbone or sulfur crosslinks formed during vulcanization to break during long vulcanization periods, resulting in a decrease in tire strength and durability.

[0004] In the production of large tires, it is required to suppress reversion during vulcanization molding, and there is a demand for the production of rubber compositions that are less susceptible to reversion.

[0005] Patent Document 1 discloses a rubber composition containing 100 parts by weight of a rubber component consisting of at least one rubber selected from natural rubber and synthetic rubber, 0.05 to 5 parts by weight of sodium 1,6-hexamethylenedithiosulfate dihydrate (HTS), and 0.05 to 5 parts by weight of a hydrazone compound, wherein the hydrazone compound is at least one selected from 3-hydroxy,N'-(1,3-dimethylbutylidene)-2-naphthoic acid hydrazide (BMH) and N'-(1,3-dimethylbutylidene) salicylic acid hydrazide (BMS). However, the technology of Patent Document 1 does not have sufficient reversion resistance.

[0006] Prior art rubber compositions require further improvement in reversion resistance to meet the demand for increased durability in automobiles. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4608076 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a rubber composition containing a zinc complex of a hydrazide compound, and a tire made using the rubber composition. [Means for solving the problem]

[0009] As a result of extensive research conducted by the present inventors to achieve the above object, they have found that by incorporating a zinc complex of a hydrazide compound having a specific structure into a rubber composition, it is possible to suppress scission of sulfur crosslinks formed by vulcanization in the rubber composition due to reversion (improving reversion resistance) compared to conventional techniques that use hydrazide compounds.

[0010] Based on this finding, the present inventors have conducted further research and have completed the present invention.

[0011] That is, the present invention provides a rubber composition and a tire containing the following zinc complex of a hydrazide compound.

[0012] Section 1. A rubber composition comprising: Diene rubber component, At least one zinc complex of a hydrazide compound selected from the group consisting of a zinc complex of a hydrazide compound represented by the following formula (1) and a zinc complex of a hydrazide compound represented by the following formula (2), and filling material A rubber composition comprising:

[0013] [ka] [In formula (1), R 1 , and R 2are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. A represents a phenyl group or a naphthyl group and has at least one polar group.

[0014] [ka] [In formula (2), R 3 , and R 4 are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. A represents a phenyl group or a naphthyl group and has at least one polar group. Section 2. the hydrazide compound represented by the formula (1) is 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide or 2-hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide, 2. The rubber composition according to claim 1, wherein the hydrazide compound represented by the formula (2) is 3-hydroxynaphthalene-2-carbohydrazide or salicylic acid hydrazide.

[0015] Section 3. A tire made using the rubber composition according to claim 1 or 2. [Effects of the Invention]

[0016] In the rubber composition of the present invention, it is possible to prevent scission of sulfur crosslinks formed by vulcanization due to reversion. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in detail below.

[0018] In this specification, the terms "comprise" and "contain" are concepts that encompass all of "comprise," "consist essentially of," and "consist only of."

[0019] In this specification, when a numerical range is indicated as "A to B," the numerical range means A or more and B or less (from the numerical value of A to the numerical value of B).

[0020] [1] Rubber composition The rubber composition of the present invention comprises: Diene rubber component, A zinc complex of a hydrazide compound represented by the following formula (1):

[0021] [ka] [In formula (1), R 1 , and R 2 are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. A represents a phenyl group or a naphthyl group and has at least one polar group. and a zinc complex of a hydrazide compound represented by the following formula (2):

[0022] [ka] [In formula (2), R 3 , and R 4 are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. A represents a phenyl group or a naphthyl group and has at least one polar group. a zinc complex of at least one hydrazide compound selected from the group consisting of: Contains filler.

[0023] In the rubber composition of the present invention, the hydrazide compound represented by the formula (1) is 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide or 2-hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide.

[0024] In the rubber composition of the present invention, the hydrazide compound represented by the formula (2) is 3-hydroxynaphthalene-2-carbohydrazide or salicylic acid hydrazide.

[0025] The rubber composition of the present invention contains a zinc complex of a hydrazide compound, which can suppress scission of sulfur crosslinks formed by vulcanization due to reversion, i.e., can improve the reversion resistance of the rubber composition.

[0026] [1-1] Hydrazide compound represented by formula (1) that constitutes a zinc complex The hydrazide compound represented by formula (1) constituting the zinc complex of the hydrazide compound is represented by the following structural formula.

[0027] [ka] [In formula (1), R 1 , and R 2 are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. A represents a phenyl group or a naphthyl group and has at least one polar group. In formula (1), R 1 , and R 2 are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0028] The alkyl group having 1 to 6 carbon atoms is preferably a linear, branched, or cyclic alkyl group. The alkyl group having 1 to 6 carbon atoms preferably has 1 to 4 carbon atoms.

[0029] In formula (1), A represents a phenyl group or a naphthyl group and has at least one polar group.

[0030] In formula (1), the polar group contained in A is not particularly limited. The polar group is preferably an amino group, an aminoalkyl group, an alkoxycarbonyl group, an acyl group, an acyloxy group, an amide group, a carboxyl group, a carboxyalkyl group, a formyl group, a nitrile group, a nitro group, a hydroxyalkyl group, a hydroxyl group, an alkoxy group, an aryloxy group, a heterocyclic group, a thiol group, an alkylthio group, an arylthio group, or the like.

[0031] The number of polar groups may be preferably 1 to 4, and more preferably 1 to 3, at substitutable positions.

[0032] The amino group is preferably an amino group represented by -NH2.

[0033] The amino group is preferably a linear or branched monoalkylamino group (substituted amino group) having 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, or 3-methylpentylamino.

[0034] The amino group is preferably a dialkylamino group (substituted amino group) having two linear or branched alkyl groups having 1 to 6 carbon atoms, such as a dimethylamino, ethylmethylamino, or diethylamino group.

[0035] Preferably, at least one of these polar groups is substituted on the carbon atom adjacent to the carbon atom to which the carbohydrazide group is bonded.

[0036] Among these polar groups, a hydroxyl group, an amino group, etc. are preferred, and a hydroxyl group is more preferred.

[0037] In the rubber composition of the present invention, the hydrazide compound represented by formula (1) constituting the zinc complex of the hydrazide compound is preferably 3-Hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide:

[0038] [ka] 2-Hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide:

[0039] [ka] is.

[0040] In the rubber composition of the present invention, the zinc complex of the hydrazide compound represented by formula (1) is preferably a zinc complex of 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide or a zinc complex of 2-hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide.

[0041] The zinc complex of the hydrazide compound represented by formula (1) is formed from 1 mole of zinc atoms per 2 moles of the hydrazide compound represented by formula (1).

[0042] [1-2] Hydrazide compound represented by formula (2) that constitutes a zinc complex The hydrazide compound represented by formula (2) constituting the zinc complex of the hydrazide compound is represented by the following structural formula.

[0043] [ka] [In formula (2), R 3 , and R 4 are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. A represents a phenyl group or a naphthyl group and has at least one polar group. In formula (2), R 3 , and R 4 are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0044] The alkyl group having 1 to 6 carbon atoms is preferably a linear, branched, or cyclic alkyl group. The alkyl group having 1 to 6 carbon atoms preferably has 1 to 4 carbon atoms.

[0045] In formula (2), R 3 , and R 4 preferably represents a hydrogen atom.

[0046] In formula (2), A represents a phenyl group or a naphthyl group and has at least one polar group.

[0047] In formula (2), the polar group contained in A is not particularly limited. The polar group is preferably an amino group, an aminoalkyl group, an alkoxycarbonyl group, an acyl group, an acyloxy group, an amido group, a carboxyl group, a carboxyalkyl group, a formyl group, a nitrile group, a nitro group, a hydroxyalkyl group, a hydroxyl group, an alkoxy group, an aryloxy group, a heterocyclic group, a thiol group, an alkylthio group, an arylthio group, or the like.

[0048] The number of polar groups may be preferably 1 to 4, and more preferably 1 to 3, at substitutable positions.

[0049] The amino group is preferably an amino group represented by -NH2.

[0050] The amino group is preferably a linear or branched monoalkylamino group (substituted amino group) having 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, or 3-methylpentylamino.

[0051] The amino group is preferably a dialkylamino group (substituted amino group) having two linear or branched alkyl groups having 1 to 6 carbon atoms, such as a dimethylamino, ethylmethylamino, or diethylamino group.

[0052] It is also preferred that at least one of these polar groups is substituted on the carbon atom adjacent to the carbon atom to which the carbohydrazide group is bonded.

[0053] Among these polar groups, a hydroxyl group, an amino group, etc. are preferred, and a hydroxyl group is more preferred.

[0054] In the rubber composition of the present invention, the hydrazide compound represented by formula (2) constituting the zinc complex of the hydrazide compound is preferably 3-Hydroxynaphthalene-2-carbohydrazide:

[0055] [ka] Salicylic hydrazide:

[0056] [ka] is.

[0057] In the rubber composition of the present invention, the zinc complex of the hydrazide compound represented by the formula (2) is preferably a zinc complex of 3-hydroxynaphthalene-2-carbohydrazide or a zinc complex of salicylic acid hydrazide.

[0058] The zinc complex of the hydrazide compound represented by formula (2) is formed from 1 mole of zinc atoms per mole of the hydrazide compound represented by formula (2).

[0059] [1-3] Amount of zinc complex of hydrazide compound In the rubber composition of the present invention, the blending ratio of at least one zinc complex of a hydrazide compound selected from the group consisting of a zinc complex of a hydrazide compound represented by Formula (1) and a zinc complex of a hydrazide compound represented by the following Formula (2) to the diene rubber component is preferably 0.05 to 30 parts by mass, more preferably 0.1 to 10 parts by mass, still more preferably 0.15 to 5 parts by mass, and particularly preferably 0.5 to 2 parts by mass, per 100 parts by mass of the diene rubber component.

[0060] In the rubber composition of the present invention, by blending at least one zinc complex of a hydrazide compound selected from the group consisting of a zinc complex of a hydrazide compound represented by formula (1) and a zinc complex of a hydrazide compound represented by the following formula (2) with a diene rubber component in the above ratio, the rubber composition is prevented from cleaving due to reversion of sulfur crosslinks formed by vulcanization, i.e., exhibits excellent reversion resistance.

[0061] The rubber composition of the present invention exhibits excellent reversion resistance, and therefore, when the rubber composition of the present invention is used in a tire, it is possible to produce a tire that exhibits excellent durability.

[0062] [1-4] Diene rubber component The rubber composition of the present invention contains a diene rubber component.

[0063] The diene rubber component is preferably natural rubber (NR), synthetic diene rubber, a mixture of natural rubber and synthetic diene rubber, or the like.

[0064] From the viewpoint of improving the durability of the rubber composition, natural rubber is preferably used. The natural rubber is preferably contained in an amount of 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and particularly preferably 70% by mass to 100% by mass, based on 100% by mass of the diene rubber component.

[0065] The natural rubber is preferably natural rubber such as natural rubber latex, technically graded rubber (TSR), smoked sheet (RSS), gutta percha, eucommia-derived natural rubber, guayule-derived natural rubber, Russian dandelion-derived natural rubber, etc. The natural rubber is preferably modified natural rubber such as epoxidized natural rubber, methacrylic acid-modified natural rubber, styrene-modified natural rubber, etc.

[0066] The synthetic diene rubber is preferably styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile rubber (NBR), chloroprene rubber (CR), ethylene-propylene-diene terpolymer rubber (EPDM), styrene-isoprene-styrene triblock copolymer (SIS), styrene-butadiene-styrene triblock copolymer (SBS), or modified synthetic diene rubbers thereof.

[0067] The modified synthetic diene rubber is preferably a diene rubber modified by a modification technique such as main chain modification, one end modification, or both ends modification.

[0068] The modified functional group of the modified synthetic diene rubber is preferably a functional group containing a hetero atom such as an epoxy group, an amino group, an alkoxy group, or a hydroxyl group, and preferably contains one or more of these functional groups.

[0069] There are no particular limitations on the cis / trans / vinyl ratio of the diene moiety, and any ratio is preferred.

[0070] There are no particular limitations on the weight average molecular weight and molecular weight distribution of the diene rubber, but the weight average molecular weight is preferably 150,000 to 1,400,000.

[0071] The method for producing the synthetic diene rubber is not particularly limited, and is preferably a synthesis method such as emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, or cationic polymerization.

[0072] The synthetic diene rubber is preferably IR, SBR, BR, or a mixture of two or more selected from these, more preferably SBR, BR, or a mixture of two or more selected from these. The synthetic diene rubber is particularly preferably a diene rubber containing a structure obtained by polymerizing 1,3-butadiene.

[0073] The glass transition temperature of the synthetic diene rubber (preferably a diene rubber containing a structure obtained by polymerizing 1,3-butadiene) is preferably in the range of -110°C to -20°C, more preferably in the range of -70°C to -20°C, from the viewpoint of achieving both abrasion resistance and braking characteristics.

[0074] [1-5] Filler The rubber composition of the present invention contains a filler (reinforcing material).

[0075] The filler is preferably a conventional filler used in the rubber industry.

[0076] The filler is preferably an inorganic filler such as silica, carbon black, or the like.

[0077] The inorganic filler is preferably silica or alumina (Al2O3) such as γ-alumina or α-alumina.

[0078] The inorganic filler is preferably alumina monohydrate (Al2O3·H2O) such as boehmite or diaspore.

[0079] The inorganic filler is preferably aluminum hydroxide [Al(OH)3] such as gibbsite or bayerite.

[0080] The inorganic filler 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 dioxide (TiO2), titanium dioxide (TiO2), titanium dioxide (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 silicates (e.g., Ca2·SiO4), calcium aluminum silicates (e.g., Al2O3·CaO·2SiO2), calcium magnesium silicate (CaMgSiO4), calcium carbonate (CaCO3), zirconium oxide (ZrO2), zirconium hydroxide [ZrO(OH)2·nH2O], zirconium carbonate [Zr(CO3)2], and crystalline aluminosilicates containing hydrogen, alkali metals, or alkaline earth metals to compensate for the charge, such as various zeolites.

[0081] In order to improve the affinity with the rubber component, the inorganic filler may preferably be an inorganic filler whose surface has been organically treated.

[0082] silica From the viewpoint of damping characteristics, the inorganic filler is preferably silica.

[0083] The BET specific surface area of ​​the silica is not particularly limited, but is preferably 40 m 2 / g~350m 2 / g range. Silica having a BET specific surface area in this range has the advantage of being able to provide both rubber reinforcement and dispersibility in the rubber component.

[0084] The BET specific surface area is measured in accordance with ISO 5794-1.

[0085] The BET specific surface area of ​​the silica is preferably in the range of 40 m 2 / g~350m 2 / g, more preferably 100m 2 / g~270m 2 / g, and particularly preferably 110m 2 / g~270m 2 / g.

[0086] 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 the product name "Nipsil AQ" manufactured by Tosoh Silica Corporation (BET specific surface area = 205 m 2 / g), "Nipsil KQ" (BET specific surface area = 240 m 2 / g), and the product name "Ultrasil VN3" manufactured by Degussa (BET specific surface area = 175 m 2 / g), etc.

[0087] carbon black The carbon black is not particularly limited, and examples thereof include commercially available carbon black and carbon-silica dual phase filler.

[0088] 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, or the like.

[0089] The carbon black is preferably a carbon black of the SAF, ISAF, IISAF, N134, N234, N330, N339, N375, HAF, FEF grade.

[0090] The range of DBP absorption of carbon black is not particularly limited, and is preferably within 60 cm 3 / 100g~200cm 3 / 100g, more preferably 70cm 3 / 100g~180cm 3 / 100g, and particularly preferably 80cm 3 / 100g~160cm 3 / 100g.

[0091] The nitrogen adsorption specific surface area (N2SA, measured in accordance with JIS K 6217-2:2001) of the 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.

[0092] The filler may be used alone or in combination of two or more kinds.

[0093] [1-6] Filler content The amount of the filler mixed is preferably 10 to 160 parts by mass, more preferably 20 to 100 parts by mass, and even more preferably 30 to 70 parts by mass, per 100 parts by mass of the diene rubber component.

[0094] [1-7] Other ingredients The rubber composition of the present invention preferably contains compounding agents commonly used in the rubber industry in addition to a diene rubber component, at least one zinc complex of a hydrazide compound selected from the group consisting of a zinc complex of a hydrazide compound represented by formula (1) and a zinc complex of a hydrazide compound represented by formula (2) below, and a filler:

[0095] The compounding agents are preferably antioxidants, antiozonants, softeners, processing aids, waxes, resins, foaming agents, oils, stearic acid, zinc oxide (ZnO), vulcanization accelerators, vulcanization retarders, vulcanizing agents (sulfur), etc., and are appropriately selected and compounded.

[0096] When silica is used as a filler, a silane coupling agent is preferably blended in order to enhance the reinforcing properties of the rubber composition by silica and to enhance the low heat buildup and wear resistance of the rubber composition. The silane coupling agent is preferably a sulfide-based, polysulfide-based, thioester-based, thiol-based, olefin-based, epoxy-based, amino-based, or alkyl-based silane coupling agent.

[0097] [2] Tires The rubber composition of the present invention is inhibited from severing sulfur crosslinks formed by vulcanization due to reversion, and thus exhibits excellent reversion resistance.

[0098] By using the rubber composition of the present invention to manufacture a tire, it is possible to manufacture a tire that exhibits excellent durability.

[0099] The tire of the present invention is preferably used as a tire for trucks, buses, heavy loads, winter tires, etc.

[0100] In the tire of the present invention, the rubber composition is preferably used in at least one member selected from the tread portion, sidewall portion, bead area portion, belt portion, carcass portion, and shoulder portion.

[0101] In the tire (pneumatic tire) of the present invention, more preferably, components such as the tread portion, bead area portion, belt portion, and carcass portion are formed from the rubber composition of the present invention.

[0102] In the tire of the present invention, the rubber composition is particularly preferably used in the tread portion. The tread portion has a tread pattern and is the outer shell portion of the tire that directly contacts the road surface, protecting the carcass and preventing wear and damage. The tread portion refers to the cap tread that constitutes the ground contact portion of the tire and / or the base tread disposed inside the cap tread.

[0103] In the tire of the present invention, the rubber composition is preferably used in other parts such as a bead area, a belt, a carcass, and a shoulder.

[0104] The bead area secures both ends of the carcass cord and at the same time secures the tire to the rim. The bead is made of bundled high-carbon steel. The belt is a reinforcing band stretched circumferentially between the radially structured tread and carcass. It tightly fastens the carcass like the hoops of a barrel, increasing the rigidity of the tread. The carcass is the cord layer that forms the skeleton of the tire, and is responsible for withstanding the load, impact, and air pressure that the tire receives. The shoulder is the shoulder of the tire, and serves to protect the carcass.

[0105] In the tire of the present invention, the rubber composition is preferably used in the sidewall portion, which is the portion of a pneumatic radial tire extending from the lower side of the shoulder portion to the bead portion. The sidewall portion protects the carcass and is the portion that is most subject to bending during running.

[0106] The tire of the present invention is preferably manufactured according to a method known in the field of tires. The gas to be filled into the tire is preferably normal air or air with an adjusted partial oxygen pressure, or an inert gas such as nitrogen, argon, or helium.

[0107] [3] Method for producing rubber composition The method for producing the rubber composition of the present invention is not particularly limited, and it can be preferably produced by mixing the compound, rubber component, filler, and other components as required.

[0108] The mixing method is not particularly limited, and preferably, the compound, rubber component, filler, and other components as required are kneaded using a kneader or the like.

[0109] Although the embodiments of the present invention have been described above, the present invention is not limited to these examples and can be embodied in various forms without departing from the spirit of the present invention. [Example]

[0110] The embodiments of the present invention will be described more specifically based on Production Examples and Examples.

[0111] The present invention is not limited to these.

[0112] [1] Preparation of hydrazide compounds Compound 1: 3-Hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide A 500 mL four-neck flask equipped with a Dean-Stark apparatus was charged with 41 g of 3-hydroxynaphthalene-2-carbohydrazide (Tokyo Chemical Industry Co., Ltd.) and 138 mL of 4-methyl-2-pentanone to form a suspension, which was then heated to approximately 116°C and refluxed for 3 hours while removing the generated water using a Dean-Stark apparatus.

[0113] The reaction solution was cooled at a rate of 1.7°C / min while stirring at 250 rpm to precipitate crystals at 80°C, and then immediately cooled at 1.7°C / min to 5°C. The precipitated crystals were collected by filtration and dried under reduced pressure to obtain 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide as pale brown crystals.

[0114] Melting point: 157.4°C 1H NMR (300 MHz, CDCl3) δ: 0.8-1.1 (6H), 1.8-2.4 (6H), 7.2-7.8 (5H), 8.4-8.5 (1H), 10.2-11.0 (1H). Hydroxyl hydrogen atoms were not detected.

[0115] 1 The 1 H NMR spectrum showed a mixture of isomers.

[0116] Compound 2: 3-hydroxynaphthalene-2-carbohydrazide Purchased from: Tokyo Chemical Industry Co., Ltd.

[0117] Compound 3: 2-Hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide In a 300 mL recovery flask equipped with a condenser, 5.00 g of salicylic acid hydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) and 100 mL of methanol were added to form a suspension, and 3.95 g of 4-methyl-2-pentanone was added and heated under reflux overnight.

[0118] The reaction mixture was concentrated under reduced pressure, and the precipitated solid was filtered and washed with a mixed solvent of hexane and ethyl acetate. The resulting solid was dried under reduced pressure to obtain 7.50 g (yield 97%) of 2-hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide as a white solid.

[0119] Melting point: 158°C 1 H NMR(500MHz,CDCl3)δ:0.9~1.1(6H),1.8~2.4(6H),6.8~6.9(1H),7.0(1H),7.4~7.5(2H),8.7~9.2(1H),10.3~13.0(1H) 1 The 1 H NMR spectrum showed a mixture of isomers.

[0120] Compound 4: Salicylic acid hydrazide Purchased from: Tokyo Chemical Industry Co., Ltd.

[0121] [2] Preparation of zinc complexes of hydrazide compounds Zinc complex of compound 1: Zinc complex of 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide (compound 5) A 300 mL recovery flask equipped with a condenser was charged with 10 g of 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide and 200 mL of methanol to form a solution, and a solution of 7.72 g of zinc acetate dihydrate in 90 mL of methanol was added dropwise.

[0122] The reaction mixture was heated and stirred at 50°C for 5 hours, and then stirred at room temperature overnight. The precipitated solid was filtered and washed with 50 mL of methanol. The resulting solid was dried under reduced pressure to obtain 10.38 g (93% yield) of a zinc complex of 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide as a yellow solid.

[0123] Melting point 250℃ or higher The change in melting point and color confirmed that a zinc complex of 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide had been produced.

[0124] Zinc complex of compound 2: Zinc complex of 3-hydroxynaphthalene-2-carbohydrazide (compound 6) A 1 L eggplant-shaped flask equipped with a condenser was charged with 2.00 g of 3-hydroxynaphthalene-2-carbohydrazide (pale yellow solid, melting point 206 °C) and 600 mL of methanol to form a solution, to which 1.30 g of zinc acetate dihydrate in 20 mL of methanol was added dropwise and heated to reflux overnight. The reaction solution was allowed to cool to room temperature, and the precipitated solid was filtered and washed with 10 mL of methanol. The resulting solid was dried under reduced pressure to obtain 1.23 g (46% yield) of 3-hydroxynaphthalene-2-carbohydrazide zinc complex as a beige solid.

[0125] Melting point 300℃ or higher The change in melting point confirmed that a zinc complex of 3-hydroxynaphthalene-2-carbohydrazide had been produced.

[0126] Zinc complex of compound 3: Zinc complex of 2-hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide (compound 7) A 200 mL recovery flask equipped with a condenser was charged with 3.00 g of 2-hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide and 40 mL of methanol to form a solution, to which a solution of 2.81 g of zinc acetate dihydrate in 30 mL of methanol was added dropwise, followed by heating and stirring at 50°C overnight.

[0127] The reaction mixture was allowed to cool to room temperature, and the precipitated solid was filtered and washed with 20 mL of methanol. The resulting solid was dried under reduced pressure to obtain 1.72 g (yield 51%) of a zinc complex of 2-hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide as a white solid.

[0128] Melting point 250℃ or higher The change in melting point confirmed that the zinc complex of 2-hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide was produced.

[0129] Zinc complex of compound 4: Zinc complex of salicylic acid hydrazide (compound 8) A 500 mL eggplant-shaped flask equipped with a condenser was charged with 5.00 g of salicylic acid hydrazide (white solid, melting point 152°C) and 185 mL of methanol to form a solution, to which 4.33 g of zinc acetate dihydrate in 45 mL of methanol was added dropwise and heated to reflux overnight. The reaction solution was allowed to cool to room temperature, and the precipitated solid was filtered and washed with 10 mL of methanol. The resulting solid was dried under reduced pressure to obtain 3.76 g (53% yield) of a zinc complex of salicylic acid hydrazide as a white solid.

[0130] Melting point 300℃ or higher The change in melting point confirmed that a zinc complex of salicylic acid hydrazide had been produced.

[0131] [3] Measurement of hydrazide and zinc contents in zinc complexes of hydrazide compounds [3-1] Hydrazide content (mass) in zinc complexes of hydrazide compounds It was measured by HPLC analysis.

[0132] Zinc complex of compound 1: Zinc complex of 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide (compound 5) Preparation of test sample solution: 10 mg of zinc complex was dissolved in 10 mL of tetrahydrofuran, and the solution was diluted to volume with methanol.

[0133] HPLC analysis conditions: Column: GL Sciences Inc., Inertsil® ODS-3 4.6 mm x 250 mm, 5 μm Injection volume: 5 μL Detection wavelength: 254 nm Column temperature: 40℃ Mobile phase: methanol / phosphate buffer = 60 / 40 (Vol) Phosphate buffer was prepared by dissolving 6 mmol of disodium hydrogen phosphate and 6 mmol of potassium dihydrogen phosphate in 1 L of distilled water.

[0134] Flow rate: 1mL / min Retention time: Detected as 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide at approximately 10 minutes.

[0135] Zinc complex of compound 2: Zinc complex of 3-hydroxynaphthalene-2-carbohydrazide (compound 6) Preparation of test sample solution: 10 mg of zinc complex was accurately weighed, and 10 mL of tetrahydrofuran, 0.1 mL of acetic acid, and 0.2 mL of 4-methyl-2-pentanone were added. The mixture was heated at 50°C overnight to dissolve, and the total volume of the solution was diluted to constant volume with methanol.

[0136] HPLC analysis conditions: Column: GL Sciences Inc., Inertsil® ODS-3 4.6 mm x 250 mm, 5 μm Injection volume: 5 μL Detection wavelength: 254 nm Column temperature: 40℃ Mobile phase: methanol / phosphate buffer = 60 / 40 (Vol) Phosphate buffer was prepared by dissolving 6 mmol of disodium hydrogen phosphate and 6 mmol of potassium dihydrogen phosphate in 1 L of distilled water.

[0137] Flow rate: 1mL / min Retention time: Detected as 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide at approximately 10 minutes.

[0138] Zinc complex of compound 3: Zinc complex of 2-hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide (compound 7) Preparation of test sample solution: 10 mg of zinc complex was dissolved in 10 mL of tetrahydrofuran, and the solution was diluted to volume with methanol.

[0139] HPLC analysis conditions: Column: GL Sciences Inc., Inertsil® ODS-3 4.6 mm x 250 mm, 5 μm Injection volume: 5 μL Detection wavelength: 254 nm Column temperature: 40℃ Mobile phase: methanol / phosphate buffer = 55 / 45 (Vol) Phosphate buffer was prepared by dissolving 6 mmol of disodium hydrogen phosphate and 6 mmol of potassium dihydrogen phosphate in 1 L of distilled water.

[0140] Flow rate: 1mL / min Retention time: Detected as 2-hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide at approximately 15 minutes.

[0141] Zinc complex of compound 4: Zinc complex of salicylic acid hydrazide (compound 8) Preparation of test sample solution: 10 mg of zinc complex was accurately weighed, and 2 mL of N,N-dimethylformamide, 0.2 mL of acetic acid, and 0.2 mL of 4-methyl-2-pentanone were added. The mixture was heated at 50°C overnight to dissolve the zinc complex, and the total volume of the solution was diluted with methanol to the constant volume.

[0142] HPLC analysis conditions: Column: GL Sciences Inc., Inertsil® ODS-3 4.6 mm x 250 mm, 5 μm Injection volume: 5 μL Detection wavelength: 254 nm Column temperature: 40℃ Mobile phase: methanol / phosphate buffer = 55 / 45 (Vol) Phosphate buffer was prepared by dissolving 6 mmol of disodium hydrogen phosphate and 6 mmol of potassium dihydrogen phosphate in 1 L of distilled water.

[0143] Flow rate: 1mL / min Retention time: Detected as 2-hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide at approximately 15 minutes.

[0144] [3-2] Zinc content (mass) in zinc complexes of hydrazide compounds It was measured by chelate titration.

[0145] Zinc complex of compound 1: Zinc complex of 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide (compound 5) Chelatometric titration conditions: Approximately 100 mg of zinc complex was accurately weighed, dissolved in 2 mL of N,N-dimethylformamide, and diluted with 10 mL of methanol. 40 mL of water, 10 mL of pH 5 acetic acid / sodium acetate buffer, and 0.5 mL of XO reagent were added to form a pink suspension. A chelate titration was performed by adding 0.1 mol / L EDTA disodium solution dropwise until the pink color of the suspension changed to yellow.

[0146] Zinc complex of compound 2: Zinc complex of 3-hydroxynaphthalene-2-carbohydrazide (compound 6) Chelatometric titration conditions: Approximately 30 mg of zinc complex was accurately weighed and dissolved in a mixed solvent of 2 mL of N,N-dimethylformamide and 0.5 mL of acetic acid, and then diluted with 10 mL of methanol. 40 mL of water, 10 mL of pH 5 acetic acid / sodium acetate buffer, and 0.5 mL of XO reagent were added to form a reddish-purple solution. A chelate titration was performed by adding 0.1 mol / L EDTA disodium solution dropwise until the reddish-purple color of this solution changed to yellow.

[0147] Zinc complex of compound 3: Zinc complex of 2-hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide (compound 7) Chelatometric titration conditions: The zinc complex of 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide was titrated in the same manner.

[0148] Zinc complex of compound 4: Zinc complex of salicylic acid hydrazide (compound 8) Chelatometric titration conditions: The zinc complex of 3-hydroxynaphthalene-2-carbohydrazide was titrated in the same manner.

[0149] Table 1 shows the hydrazide content, zinc content, and content ratio (mass ratio) in the zinc complexes of various hydrazide compounds.

[0150] Compound 1: 3-Hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide Compound 2: 3-hydroxynaphthalene-2-carbohydrazide Compound 3: 2-Hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide Compound 4: Salicylic acid hydrazide Compound 5: Zinc complex of Compound 1 Compound 6: Zinc complex of compound 2 Compound 7: Zinc complex of compound 3 Compound 8: Zinc complex of compound 4

[0151] [Table 1]

[0152] [2] Examples 1 to 4 and Comparative Examples 1 to 4: Production of rubber compositions The components shown in Table 2 were mixed in the proportions (parts by mass) and kneaded in a plastomill to prepare rubber compositions. Each prepared rubber composition was evaluated for reversion resistance by the following method.

[0153] Resistance to reversion The unvulcanized rubber obtained by kneading in a Plastomill was subjected to a vulcanization curve measurement at 150°C for 60 minutes using a vulcanization tester (manufactured by M&K Co., Ltd.). The maximum torque during vulcanization was designated "MH," and the torque after 60 minutes was designated "M60." The reversion resistance was quantified using the following formula.

[0154] Reversion resistance=(MH-M60) / MH The reversion resistance was expressed as an index, which is a numerical value of the reversion resistance. The reversion resistance index of the Examples (zinc complexes of hydrazide compounds) was expressed relative to the reversion resistance index of the Comparative Examples (hydrazide compounds) that were used for comparison.

[0155] Reversion resistance index of example (zinc complex of hydrazide compound) =Reversion resistance of Example (zinc complex of hydrazide compound) / Reversion resistance of comparative example (hydrazide compound) x 100 Reversion resistance index of Example 1 (Compound 5) =Reversion resistance of Example 1 (Compound 5) / Reversion resistance of Comparative Example 1 (Compound 1)×100 Reversion resistance index of Example 2 (Compound 6) =Reversion resistance of Example 2 (Compound 6) / Reversion resistance of Comparative Example 2 (Compound 2)×100 Reversion resistance index of Example 3 (Compound 7) =Reversion resistance of Example 3 (Compound 7) / Reversion resistance of Comparative Example 3 (Compound 3)×100 Reversion resistance index of Example 4 (Compound 8) =Reversion resistance of Example 4 (Compound 8) / Reversion resistance of Comparative Example 4 (Compound 4)×100 The smaller the index value of reversion resistance, the lower the rate of reduction in torque from the maximum value, indicating that severance of sulfur crosslinks due to reversion has occurred less frequently, and thus indicating better reversion resistance.

[0156] The evaluation results are shown in Table 2.

[0157] [Table 2] *1: N234 grade *2: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) *3: N-cyclohexyl-2-benzothialylsulfenamide (CBS) *4: Compound 1 *5: Compound 2 *6: Compound 3 *7:Compound 4 *8: Compound 5 (zinc complex of Compound 1) *9: Compound 6 (zinc complex of Compound 2) *10: Compound 7 (zinc complex of Compound 3) *11: Compound 8 (zinc complex of compound 4) [Industrial Applicability]

[0158] The rubber composition of the present invention exhibits excellent reversion resistance by containing a diene rubber component, a zinc complex of a hydrazide compound, and a filler.

[0159] By using the rubber composition of the present invention to manufacture a tire, it is possible to manufacture a tire that exhibits excellent durability.

Claims

1. A rubber composition comprising: Diene rubber component, At least one zinc complex of a hydrazide compound selected from the group consisting of a zinc complex of a hydrazide compound represented by the following formula (1) and a zinc complex of a hydrazide compound represented by the following formula (2), and filling material A rubber composition comprising: 【Chemical 1】 [In formula (1), R 1 , and R 2 are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. A represents a phenyl group or a naphthyl group and has at least one hydroxyl group. 【Chemistry 2】 [In formula (2), R 3 , and R 4 are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. A represents a phenyl group or a naphthyl group and has at least one hydroxyl group.

2. the hydrazide compound represented by the formula (1) is 3-hydroxy-N'-(4-methylpentan-2-ylidene)naphthalene-2-carbohydrazide or 2-hydroxy-N'-(4-methylpentan-2-ylidene)benzoic acid hydrazide, 2. The rubber composition according to claim 1, wherein the hydrazide compound represented by formula (2) is 3-hydroxynaphthalene-2-carbohydrazide or salicylic acid hydrazide.

3. A tire made using the rubber composition according to claim 1 or 2.

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