Rubber composition, tire and rubber additive

Abstract

This rubber composition comprises a rubber component and at least one compound selected from the group consisting of compounds represented by formulae (1) to (7) and 3-methyl-5-pyrazolone. [in the formulae, R represents a hydrazide group, an N'-alkylidene hydrazide group, an N-allyl carbamoyl group, a 3-carboxyl acryloyl group, a hydrazine carboxyamino group, a thiocarboxyl group, a thiol group, or a hydrogen atom. R4 is a sulfur atom or an oxygen atom. R5 is a thiol group or a hydroxy group. R6 is an alkylene group having 1 to 4 carbon atoms. R7 is an alkyl group, an aralkyl group, or a heterocyclic group. R8 is a hydrogen atom or an amino group. R9 is a hetero atom. R10 is a heterocyclic group.]

Description

[Technical field]

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

[0002] 2. Description of the Related Art As performance requirements for tires increase, the use of various rubber additives in rubber materials for constructing tires has been considered.

[0003] One of the performance requirements for tires is high mechanical strength, more specifically, high tear strength, and rubber additives that meet this requirement are in demand.

[0004] In order to solve these problems, for example, rubber compositions containing a rubber component, carbon black, and a triazole compound (Patent Documents 1 and 2) have been proposed, but it cannot be said that sufficient mechanical strength is obtained. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2010-242013 [Patent Document 2] International Publication No. 2019 / 027022 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above circumstances, an object of the present invention is to provide a rubber composition or a rubber additive for producing a tire having high tear strength. [Means for solving the problem]

[0007] As a result of intensive research conducted by the present inventors to achieve the above object, it was found that a rubber composition having high tear strength can be provided by using a compound having a specific structure as a rubber additive. Based on this finding, the present inventors conducted further research and completed the present invention.

[0008] That is, the present invention provides the following rubber composition, tire, and rubber additive. Section 1. A rubber composition comprising at least one compound selected from the group consisting of compounds represented by the following formulas (1) to (7) and 3-methyl-5-pyrazolone, and a rubber component. [ka] [In the formula, R group represents a hydrazide group, an N'-alkylidenehydrazide group, an N-allylcarbamoyl group, a 3-carboxylacryloyl group, a hydrazinecarboxyamino group, a thiocarboxyl group, a thiol group, or a hydrogen atom. 4 R is a sulfur atom or an oxygen atom. 5 R is a thiol group or a hydroxyl group. 6 R is an alkylene group having 1 to 4 carbon atoms. 7 R is an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group. 8 R is a hydrogen atom or an amino group. 9 is a heteroatom. 10 is a heterocyclic group. Section 2. In the general formula (1) or (5), the R group is R 1 where R 1 is a hydrazide group, an N'-alkylidenehydrazide group, a thiocarboxyl group, an N-allylcarbamoyl group, a 3-carboxylacryloyl group, or a hydrazinecarboxyamino group. Section 3. In the general formula (3), (4) or (6), R is R 2 where R 2is a hydrazide group, an N'-alkylidenehydrazide group, a thiol group, an N-allylcarbamoyl group, a 3-carboxylacryloyl group, or a hydrazinecarboxyamino group. Section 4. In the general formula (2), R is R 3 where R 3 is a hydrogen atom, a hydrazide group, an N'-alkylidenehydrazide group, a thiol group, an N-allylcarbamoyl group, a 3-carboxylacryloyl group, or a hydrazinecarboxyamino group. Section 5. R in general formula (7) 9 is an oxygen atom, a sulfur atom, or NR 11 and R 11 5. The rubber composition according to any one of items 1 to 4, wherein is a hydrogen atom or an amino group. Section 6. R in general formula (7) 10 6. The rubber composition according to any one of items 1 to 5, wherein is a nitrogen-containing heterocyclic group. Section 7. Item 7. The rubber composition according to item 6, wherein the nitrogen-containing heterocyclic group is a six-membered ring group. Section 8. the nitrogen-containing heterocyclic group is a pyridyl group which may have a substituent, Item 8. The rubber composition according to item 6 or 7, wherein the pyridyl group is a 2-pyridyl group, a 3-pyridyl group, or a 4-pyridyl group. Section 9. Item 9. A tire using the rubber composition according to any one of items 1 to 8. Section 10. A rubber additive comprising at least one compound selected from the group consisting of compounds represented by the following (1) to (7) and 3-methyl-5-pyrazolone: [ka] [In the formula, R group represents a hydrazide group, an N'-alkylidenehydrazide group, an N-allylcarbamoyl group, a 3-carboxylacryloyl group, a hydrazinecarboxyamino group, a thiocarboxyl group, a thiol group, or a hydrogen atom. 4 R is a sulfur atom or an oxygen atom. 5 R is a thiol group or a hydroxyl group. 6 R is an alkylene group having 1 to 4 carbon atoms. 7 R is an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group. 8 R is a hydrogen atom or an amino group. 9 is a heteroatom. 10 is a heterocyclic group. Section 11. Item 11. The rubber additive according to item 10, which is a tear strength imparting agent. Effect of the Invention

[0009] According to the rubber composition or rubber additive of the present invention, a tire having high tear strength can be provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1. Rubber composition The rubber composition of the present invention is a rubber composition containing at least one selected from the group consisting of compounds represented by formulas (1), (2), (3), (4), (5), (6), and (7) described below, and 3-methyl-5-pyrazolone, as well as a rubber component. It also contains other components as necessary. A rubber material obtained by using the rubber composition has high tear strength and can be suitably used, for example, in tires.

[0011] 1.1. Compounds represented by formulas (1) to (7) and 3-methyl-5-pyrazolone The compounds represented by the formulas (1) to (7) contained in the rubber composition are as follows.

[0012] [ka] [In the formula, R group represents a hydrazide group, an N'-alkylidenehydrazide group, an N-allylcarbamoyl group, a 3-carboxylacryloyl group, a hydrazinecarboxyamino group, a thiocarboxyl group, a thiol group, or a hydrogen atom. 4 R is a sulfur atom or an oxygen atom. 5 R is a thiol group or a hydroxyl group. 6 R is an alkylene group having 1 to 4 carbon atoms. 7 R is an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group. 8 R is a hydrogen atom or an amino group. 9 is a heteroatom. 10 is a heterocyclic group.

[0013] The hydrazide group is a group represented by the following formula (8).

[0014] [ka]

[0015] The N'-alkylidenehydrazide group is a group represented by the following formula (9): 12 , and R 13 are each independently a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group. Among these, the alkyl group, the aralkyl group, the aryl group, and the heterocyclic group may have any substituent.

[0016] [ka]

[0017] The N-allylcarbamoyl group, the 3-carboxylacryloyl group, and the hydrazinecarboxyamino group are groups represented by the following formulas (10), (11), and (12), respectively.

[0018] [ka]

[0019] R 6 The alkylene group having 1 to 4 carbon atoms constituting the formula (I) may be linear or branched, and may have any substituent.

[0020] R 7 is an alkyl group, an aralkyl group, an aryl group or a heterocyclic group. These alkyl groups, aralkyl groups, aryl groups and heterocyclic groups may have any substituent.

[0021] R 9 is a heteroatom. The heteroatom includes an oxygen atom, a sulfur atom, and NR 11 (where R 11 is a hydrogen atom or an amino group.

[0022] R 10 is a heterocyclic group, and the heterocyclic group may further have any substituent.

[0023] In the present specification, the term "alkyl group" is not particularly limited, and examples thereof include linear, branched, or cyclic alkyl groups, and specific examples thereof include linear or branched alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, 1-ethylpropyl, n-pentyl, neopentyl, n-hexyl, isohexyl, and 3-methylpentyl groups; and cyclic alkyl groups having 3 to 8 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Preferred alkyl groups are linear or branched alkyl groups having 1 to 6 carbon atoms, more preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or n-pentyl groups, and particularly preferably methyl or ethyl groups.

[0024] In the present specification, the "aralkyl group" is not particularly limited, and examples thereof include benzyl, phenethyl, trityl, 1-naphthylmethyl, 2-(1-naphthyl)ethyl, 2-(2-naphthyl)ethyl groups, etc. More preferred aralkyl groups are benzyl and phenethyl groups, and more preferred is benzyl.

[0025] In the present specification, the "aryl group" is not particularly limited, and examples thereof include phenyl, biphenyl, naphthyl, dihydroindenyl, 9H-fluorenyl, etc. More preferred aryl groups are phenyl and naphthyl groups, and particularly preferred is phenyl.

[0026] In the present specification, the "heterocyclic group" is not particularly limited, and examples thereof include 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrazinyl, 2-pyrimidyl, 4-pyrimidyl, 5-pyrimidyl, 3-pyridazyl, 4-pyridazyl, 4-(1,2,3-triazyl), 5-(1,2,3-triazyl), 2-(1,3,5-triazyl), 3-(1,2,4-triazyl), 5-(1,2,4-triazyl), 6-(1,2,4-triazyl), 2-quinolyl, 3-quinolyl, 4-quinolyl, 5-quinolyl, 6-quinolyl, 7-quinolyl, 8-quinolyl, 1- Isoquinolyl, 3-isoquinolyl, 4-isoquinolyl, 5-isoquinolyl, 6-isoquinolyl, 7-isoquinolyl, 8-isoquinolyl, 2-quinoxalyl, 3-quinoxalyl, 5-quinoxalyl, 6-quinoxalyl, 7-quinoxalyl, 8-quinoxalyl, 3-cinnolyl, 4-cinnolyl, 5-cinnolyl, 6-cinnolyl, 7-cinnolyl, 8-cinnolyl, 2-quinazolyl, 4-quinazolyl, 5-quinazolyl, 6-quinazolyl, 7-quinazolyl, 8-quinazolyl, 1-phthalazyl, 4-phthalazyl, 5-phthalazyl, 6-phthalazyl, 7-phthalazyl , 8-phthalazyl, 1-tetrahydroquinolyl, 2-tetrahydroquinolyl, 3-tetrahydroquinolyl, 4-tetrahydroquinolyl, 5-tetrahydroquinolyl, 6-tetrahydroquinolyl, 7-tetrahydroquinolyl, 8-tetrahydroquinolyl, 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, 2-furyl, 3-furyl, 2-thienyl, 3-thienyl, 1-imidazolyl, 2-imidazolyl, 4-imidazolyl, 5-imidazolyl, 1-pyrazolyl, 3-pyrazolyl, 4-pyrazolyl, 5-pyrazolyl, 2-oxazolyl, 4-oxazolyl, 5- Oxazolyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl, 3-isothiazolyl, 4-isothiazolyl, 5-isothiazolyl, 4-(1,2,3-thiadiazolyl), 5-(1,2,3-thiadiazolyl), 3-(1,2,5-thiadiazole), 2-(1,3,4-thiadiazole), 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 Zoimidazolyl, 7-benzimidazolyl, 2-benzofuranyl, 3-benzofuranyl, 4-benzofuranyl, 5-benzofuranyl, 6-benzofuranyl, 7-benzofuranyl, 1-isobenzofuranyl, 3-isobenzofuranyl, 4-isobenzofuranyl, 5-isobenzofuranyl, 6-isobenzofuranyl, 7-isobenzofuranyl, 2-benzothienyl, 3-benzothienyl, 4-benzothienyl, 5-benzothienyl, 6-benzothienyl, 7-benzo thienyl, 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, Examples of the heterocyclic group include 2-piperazyl, 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, 2-tetrahydrofuranyl, 3-tetrahydrofuranyl, 2-tetrahydrothienyl, and 3-tetrahydrothienyl. Among these, preferred heterocyclic groups are pyridyl, furanyl, thienyl, pyrimidyl, and pyrazyl, and more preferred is pyridyl.

[0027] As described above, the alkyl group, aralkyl group, aryl group, or heterocyclic group may each have one or more substituents. The "substituents" are not particularly limited, and examples thereof include 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, and arylthio groups. The number of the substituents may be preferably 1 to 5, and more preferably 1 to 3.

[0028] Each of these alkyl groups, alkylthio groups, aralkyl groups, aryl groups, arylthio groups, heterocyclic groups, and amino groups may have one or more substituents. The "substituents" are not particularly limited, and examples thereof include 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, and arylthio groups. The number of the substituents may be preferably 1 to 5, and more preferably 1 to 3.

[0029] In addition, in this specification, the term "amino group" includes not only an amino group represented by -NH2, but also substituted amino groups such as linear or branched monoalkylamino groups 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, and 3-methylpentylamino groups; and dialkylamino groups having two linear or branched alkyl groups having 1 to 6 carbon atoms, such as dimethylamino, ethylmethylamino, and diethylamino groups.

[0030] Here, the R group in the structural formula of the compound represented by formula (1) and the compound represented by formula (5) is R 1 where R 1 is a hydrazide group, an N'-alkylidenehydrazide group, a thiocarboxyl group, an N-allylcarbamoyl group, a 3-carboxylacryloyl group, or a hydrazinecarboxyamino group. Of these, it is more preferable to employ a hydrazide group.

[0031] In addition, the R group in the structural formula of the compound represented by formula (3), the compound represented by formula (4), and the compound represented by formula (6) is R 2 where R 2 is a hydrazide group, an N'-alkylidenehydrazide group, a thiol group, an N-allylcarbamoyl group, a 3-carboxylacryloyl group, or a hydrazinecarboxyamino group.

[0032] Among the above, it is more preferable to adopt a hydrazide group as the R group in the structural formula of the compound represented by formula (3) and the compound represented by formula (4), and it is more preferable to adopt a thiol group as the R group in the structural formula of the compound represented by formula (6).

[0033] In addition, R in the structural formula of the compound represented by formula (3) 5 It is more preferable to use a hydroxy group as R in the structural formula of the compound represented by formula (4). 6 It is more preferable to adopt a methylene group as R 7 It is more preferable to adopt a methyl group as R in the structural formula of the compound represented by formula (6). 8 It is more preferable to adopt an amino group represented by -NH2 as the substituent.

[0034] The R group in the structural formula of the compound represented by formula (2) is R 3 where R 3is a hydrogen atom, a hydrazide group, an N'-alkylidenehydrazide group, a thiol group, an N-allylcarbamoyl group, a 3-carboxylacryloyl group, or a hydrazinecarboxyamino group. Among these, it is more preferable to adopt a hydrogen atom as the R group in the structural formula of the compound represented by formula (2).

[0035] Furthermore, R in the structural formula of the compound represented by formula (2) 4 It is more preferable to adopt an oxygen atom as the group.

[0036] R in the structural formula of the compound represented by formula (7) 9 is a heteroatom. The heteroatom is an oxygen atom, a sulfur atom, or NR 11 (where R 11 is a hydrogen atom or an amino group. ) is preferable, and -NNH2 is particularly preferable.

[0037] In addition, R in the structural formula of the compound represented by formula (7) 10 is a heterocyclic group. The heterocyclic group is preferably a nitrogen-containing heterocyclic group, more preferably a nitrogen-containing six-membered ring group, and even more preferably a pyridyl group. Here, the pyridyl group may be any of a 2-pyridyl group, a 3-pyridyl group, and a 4-pyridyl group, and may further have a substituent. Among these, R 10 As the pyridyl group, it is particularly preferable to adopt an unsubstituted 2-pyridyl group, an unsubstituted 3-pyridyl group, or an unsubstituted 4-pyridyl group, and it is most preferable to adopt an unsubstituted 2-pyridyl group.

[0038] As the compounds represented by the above formulas (1), (2), (3), (4), (5), (6) and (7), it is particularly preferable to employ compounds represented by the following formulas (1-A), (2-A), (3-A), (4-A), (5-A), (6-A) and (7-A), respectively.

[0039] [ka]

[0040] In the present invention, in addition to the compounds represented by the above formulas (1), (2), (3), (4), (5), (6) or (7), it is also preferable to employ 3-methyl-5-pyrazolone.

[0041] In the present invention, among the compounds represented by the above formulas (1) to (7) and 3-methyl-5-pyrazolone, the compound represented by formula (1) or formula (3) is particularly preferred.

[0042] 1.2.Rubber components In this specification, the rubber component is not particularly limited, and examples thereof include natural rubber (NR), synthetic diene rubber, and diene rubber such as a mixture of natural rubber and synthetic diene rubber, as well as other non-diene rubbers.

[0043] Examples of natural rubber include natural rubber latex, technically graded rubber (TSR), smoked sheet rubber (RSS), gutta percha, eucommia-derived natural rubber, guayule-derived natural rubber, and Russian dandelion-derived natural rubber, as well as modified natural rubber such as epoxidized natural rubber, methacrylic acid-modified natural rubber, and styrene-modified natural rubber.

[0044] Examples of synthetic diene rubbers include styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile rubber (NBR), chloroprene rubber (CR), ethylene-propylene-diene ternary copolymer rubber (EPDM), styrene-isoprene-styrene ternary block copolymer (SIS), styrene-butadiene-styrene ternary block copolymer (SBS), and modified synthetic diene rubbers thereof. Examples of modified synthetic diene rubbers include diene rubbers modified by main chain modification, one-end modification, and both-end modification. Here, examples of modified functional groups of modified synthetic diene rubbers include those containing one or more types of heteroatom-containing functional groups such as epoxy groups, amino groups, alkoxy groups, and hydroxyl groups. There is no particular restriction on the cis / trans / vinyl ratio of the diene portion, and any ratio can be suitably used. There is no particular restriction on the average molecular weight and molecular weight distribution of the diene rubber, and an average molecular weight of 5 to 3 million can be suitably used. The method for producing the synthetic diene rubber is not particularly limited, and examples thereof include those synthesized by emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, cationic polymerization, and the like.

[0045] As the non-diene rubber, a wide variety of known rubbers can be used.

[0046] The rubber component preferably contains a diene rubber, and per 100 parts by mass of the rubber component, the diene rubber is preferably contained in an amount of 50 parts by mass or more, more preferably 75 parts by mass or more, and particularly preferably 80 to 100 parts by mass.

[0047] In terms of achieving both abrasion resistance and braking characteristics, the glass transition point of the diene rubber is preferably in the range of -70°C to -20°C. In the rubber composition of the present invention, it is preferable that 50% by mass or more of the diene rubber is a diene rubber having a glass transition point in the range of -70°C to -20°C.

[0048] The rubber component may be used alone or in a mixture (blend) of two or more. Among them, preferred rubber components are natural rubber, IR, SBR, BR, or a mixture of two or more selected from these, and more preferred are natural rubber, SBR, BR, or a mixture of two or more selected from these. There are no particular limitations on the blend ratio, but it is preferred to blend 50 to 100 parts by mass of SBR, BR, or a mixture of these, and more preferred to blend 75 to 100 parts by mass of SBR, BR, or a mixture of these, in 100 parts by mass of the rubber component. When blending a mixture of SBR and BR, it is preferred that the total amount of SBR and BR is within the above range. It is preferred that SBR is 50 to 100 parts by mass and BR is 0 to 50 parts by mass.

[0049] The compounding ratio of the compounds represented by the above formulas (1) to (7) and 3-methyl-5-pyrazolone to the rubber component is preferably 0.1 to 50 parts by mass, more preferably 0.2 to 10 parts by mass, in total, per 100 parts by mass of the rubber component. By compounding at this ratio, the effect of improving the tear strength can be effectively obtained.

[0050] The rubber composition of the present invention contains a rubber component and at least one selected from the group consisting of the compounds represented by formulas (1) to (7) and 3-methyl-5-pyrazolone, and the rubber component and the compound are bonded to form a crosslinked body (gel). This crosslinked body is formed by combining the R groups in the compounds represented by formulas (1) to (6) and the R groups in the compound represented by formula (7). 9 and a strong bond such as a covalent bond between the methylene group at the 4th position of 3-methyl-5-pyrazolone and a rubber component, and a site other than the R group in the compounds represented by formulas (1) to (6), a site other than the methylene group at the 4th position of 3-methyl-5-pyrazolone, and R in the compound represented by formula (7). 9 , R 10In the case of nitrogen atoms, it is considered that these are formed by relatively weak bonds such as hydrogen bonds between these sites or between the rubber component and compounding agents such as zinc oxide (ZnO). In this specification, such a crosslinked product is called a "soft gel." When this soft gel is formed in a rubber composition, the number of crosslinking points increases compared to a product with only covalent crosslinks (in this specification, such a crosslinked product is called a "hard gel"), and therefore mechanical properties such as breaking strength are improved.

[0051] 1.3.Other Ingredients In addition to the above-mentioned compounds and rubber components, the rubber composition of the present invention may contain fillers and compounding agents commonly used in the rubber industry, such as antioxidants, antiozonants, softeners, processing aids, waxes, resins, foaming agents, oils, stearic acid, zinc oxide (ZnO), vulcanization accelerators, vulcanization retarders, vulcanizing agents (sulfur), and the like, which are appropriately selected and compounded within ranges that do not impair the objects of the present invention.

[0052] As the filler, a wide variety of fillers known in the rubber industry can be used, including, but not limited to, carbon black and inorganic fillers.

[0053] The carbon black is not particularly limited, and examples thereof include commercially available carbon black, Carbon-Silica Dual phase filler, and the like.

[0054] Specifically, examples of carbon black include high, medium or low structure SAF, ISAF, IISAF, N110, N134, N220, N234, N330, N339, N375, N550, HAF, FEF, GPF, SRF grade carbon black, etc. Among them, preferred carbon black is SAF, ISAF, IISAF, N134, N234, N330, N339, N375, HAF or FEF grade carbon black.

[0055] The DBP absorption of carbon black is not particularly limited, but is preferably 60 to 200 cm3 / 100g, more preferably 70~180cm 3 / 100g, especially preferably 80-160cm 3 / 100g.

[0056] The nitrogen adsorption specific surface area (N2SA, measured in accordance with JIS K 6217-2:2001) of the carbon black is preferably 30 to 200 m 2 / g, more preferably 40 to 180m 2 / g, particularly preferably 50 to 160m 2 / g.

[0057] There are no particular limitations on the inorganic filler, so long as it is an inorganic compound that is commonly used in the rubber industry. Examples of inorganic compounds that can be used include alumina (Al2O3) such as silica, 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.) Examples of such inorganic fillers include calcium silicate (Ca2·SiO4, etc.), aluminum calcium silicate (Al2O3·CaO·2SiO2, etc.), magnesium calcium silicate (CaMgSiO4), calcium carbonate (CaCO3), zirconium oxide (ZrO2), zirconium hydroxide [ZrO(OH)2·nH2O], zirconium carbonate [Zr(CO3)2], and crystalline aluminosilicates containing hydrogen, alkali metals, or alkaline earth metals to correct the charge, such as various zeolites. The surfaces of these inorganic fillers may be organically treated to improve their affinity with the rubber component.

[0058] Among these, silica is preferred as the inorganic filler from the viewpoint of damping properties. The BET specific surface area of ​​silica is not particularly limited and may be, for example, 40 to 350 m. 2 / g. Silica with a BET specific surface area in this range has the advantage of being able to achieve both rubber reinforcing properties and dispersibility in the rubber component. The BET specific surface area is measured in accordance with ISO 5794 / 1.

[0059] From this viewpoint, preferred silica has a BET specific surface area of ​​50 to 250 m 2 / g, and more preferably, the BET specific surface area is 100 to 270 m 2 / g, and particularly preferably, the silica has a BET specific surface area of ​​110 to 270 m 2 / g range.

[0060] A commercially available product of this type of silica is 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 Ultrasil VN3 (BET specific surface area = 175 m 2 / g) etc.

[0061] The amount of the filler mixed is usually 20 to 120 parts by mass, preferably 30 to 100 parts by mass, and more preferably 40 to 90 parts by mass, based on 100 parts by mass of the rubber component.

[0062] 2. Tires By producing a tire using the above-mentioned rubber composition of the present invention, a tire excellent in mechanical properties, especially in tear strength, can be obtained.

[0063] In the tire of the present invention, the rubber composition is used in at least one member selected from the group consisting of the tread portion, the sidewall portion, the bead area portion, the belt portion, the carcass portion and the shoulder portion.

[0064] Among these, one of the most preferred embodiments is to form the tire tread portion of a pneumatic tire from the rubber composition.

[0065] The tread portion has a tread pattern and is the outer shell of the tire that comes into direct contact with the road surface, protecting the carcass and preventing wear and damage. It refers to the cap tread that constitutes the tire's contact area and / or the base tread that is disposed inside the cap tread.

[0066] The sidewall portion is, for example, a portion of a pneumatic radial tire extending from the lower side of the shoulder portion to the bead portion, which protects the carcass and is the portion that is most subject to bending during running.

[0067] The bead area is the part that fixes both ends of the carcass cord and at the same time fixes the tire to the rim. The bead is a structure made of bundles of high carbon steel.

[0068] The belt section is a reinforcing band stretched in the circumferential direction between the radial tread and the carcass. It tightens the carcass like a barrel hoop, increasing the rigidity of the tread.

[0069] The carcass portion is a portion of the cord layer that forms the skeleton of the tire, and plays a role in withstanding the load, impact, and inflated air pressure that the tire receives.

[0070] The shoulder portion is the part of the tire that serves to protect the carcass.

[0071] The tire of the present invention can be manufactured according to a method known in the field of tires. The gas to be filled in the tire can be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium.

[0072] 3. Rubber additives The compounds represented by the above formulas (1) to (7) and 3-methyl-5-pyrazolone can impart high tear strength to the rubber material formed by using them as rubber additives. Such rubber additives may be at least one compound selected from the group consisting of the compounds represented by the formulas (1) to (7) and 3-methyl-5-pyrazolone, that is, at least one compound selected from the group consisting of the compounds represented by the formulas (1) to (7) and 3-methyl-5-pyrazolone, or may contain other components within a range that does not impair the effects of the additives. As such other components, for example, known oils, resins, stearic acid, zinc oxide (ZnO), calcium carbonate, silica, and the like can be widely used.

[0073] 4. Tear strength imparting agent As described above, the rubber additive of the present invention can impart excellent tear strength to a rubber material, and can be suitably used as a tear strength imparting agent.

[0074] 5. Method for producing rubber composition The method for producing the rubber composition of the present invention is not particularly limited, and for example, the rubber composition can be obtained by mixing at least one selected from the group consisting of the above-mentioned rubber component, the compounds represented by the formulas (1) to (7), and 3-methyl-5-pyrazolone, and, if necessary, other components. The rubber components (1) to (7) and 3-methyl-5-pyrazolone may also be produced by known methods.

[0075] The method for mixing the above is not particularly limited, and a wide variety of known methods can be used.Specifically, the above rubber component, at least one selected from the group consisting of the compounds represented by formulas (1) to (7) and 3-methyl-5-pyrazolone, and other components as necessary, are kneaded using a kneader or the like.

[0076] Although the embodiment of the present invention has been described above, the present invention is not limited to these examples, and it is needless to say that the present invention can be embodied in various forms without departing from the gist of the present invention. EXAMPLES

[0077] Hereinafter, the embodiments of the present invention will be described more specifically based on examples, but the present invention is not limited to these.

[0078] Preparation Example 1: Preparation of 2-hydrazinyl-2-oxoacetamide (Compound 1-A) 5.91 g of ethyl oxamate and 4.29 g of 100% hydrazine monohydrate were added to 50 mL of methanol and stirred at 65° C. for 15 hours. The reaction solution was cooled and then filtered, and the resulting solid was washed with methanol. The resulting solid was dried under reduced pressure to obtain 4.68 g of the target product (yield 90%). 1H-NMR (400MHz, DMSO-d6, δppm): 4.5(br-s,2H), 7.7(br-s,1H), 8.0(br-s,1H),9.9(br-s,1H) Melting point: 213℃

[0079] Preparation Example 2: Preparation of 2-amino-3-hydroxypropanehydrazide (Compound 3-A) 50.0 mL of a methanol solution containing 7.81 g of DL-methylserine hydrochloride was cooled to 0°C, and 6.20 g of triethylamine and 2.86 g of 100% hydrazine monohydrate were added in that order. The reaction solution was stirred at 65°C for 16 hours, and the solvent was then distilled off. 50.0 mL of tetrahydrofuran was added to the residue, the reaction solution was filtered, and the resulting solid was washed with methanol. The resulting solid was dried under reduced pressure to obtain 3.84 g of the target product (yield 64%). 1H-NMR (500MHz, DMSO-d6, δppm): 3.7(m,3H),4.4(br-s,2H),5.5(br-s,1H),8.2(br-s,2H),9.6(br-s,1H) Melting point: 183℃

[0080] Preparation Example 3: Preparation of 2-(3-methyl-5-oxo-4,5-dihydro-1H-pyrazol-4-yl)acetohydrazide (Compound 4-A) 14.0 g of dimethyl acetylsuccinate and 7.82 g of 100% hydrazine monohydrate were added to 40 mL of methanol and stirred at 65° C. for 4 hours. The reaction solution was cooled and then filtered, and the obtained solid was washed with methanol. The obtained solid was dried under reduced pressure to obtain 10.7 g of the target product (yield 84%). 1H-NMR (500MHz, DMSO-d6, δppm): 2.1(s,3H), 3.0(s,2H), 3.3(br-s,1H), 9.0(br-s,1H), NH(1H), NH2(2H) not detected Melting point: 183℃

[0081] Preparation Example 4: Preparation of 4H-1,2,4-triazole-3-carbohydrazide (Compound 5-A) 12.5 g of methyl 1,2,4-triazole-3-carboxylate and 9.85 g of 100% hydrazine monohydrate were added to 100 mL of methanol and stirred at 65° C. for 15 hours. The reaction solution was cooled and then filtered, and the obtained solid was washed with methanol. The obtained solid was dried under reduced pressure to obtain 12.3 g of the target product (yield 98%). 1H-NMR (500MHz, DMSO-d6, δppm): 4.5(br-s,2H),8.4(br-s,1H),9.8(br-s,1H),14.5(br-s,1H) Melting point: 208℃

[0082] Preparation Example 5: Preparation of 2-(pyridin-2-yl)-1,3,4-oxadiazole (compound 7-B) 16.5 g of 2-pyridinecarboxylic acid hydrazide and 2.4 g of tosylic acid monohydrate were added to 66.0 mL of triethyl orthoformate and stirred at 145°C for 6 hours. The reaction solution was cooled to room temperature, poured into an aqueous solution of sodium hydrogen carbonate, and extracted with ethyl acetate. After distilling off the solvent, the precipitated solid was recrystallized from hexane and ethyl acetate. The obtained solid was dried under reduced pressure to obtain 7.81 g of the target product (yield 44%). 1 H-NMR (400MHz, DMSO-d6, δppm): 7.7(m,1H), 8.1(m,1H), 8.2(m,1H),8.8(m,1H), 9.4(s,1H) Melting point: 119℃

[0083] Preparation Example 6: Preparation of 3-(pyridin-2-yl)-4H-1,2,4-triazol-4-amine (Compound 7-A) 4.41 g of 2-(pyridin-2-yl)-1,3,4-oxadiazole (compound 7-B) and 6.31 g of 100% hydrazine monohydrate were added to 28 mL of butanol, and the mixture was stirred at 117° C. for 20 hours, after which the solvent was distilled off. 25 mL of diethyl ether and 25 mL of isopropyl alcohol were added to the residue, the reaction solution was filtered, and the obtained solid was washed. The obtained solid was dried under reduced pressure to obtain 3.00 g of the target product (yield 62%). 1 H-NMR (400MHz, DMSO-d6, δppm): 4.6(br-s,2H), 7.6(m,1H), 8.0(m,1H),8.6(m,1H), 9.9(br-s,1H) Melting point: 101℃

[0084] Examples 1 to 9 and Comparative Examples 1 to 4: Production of Rubber Compositions The components shown in step (I) in Table 1 below were mixed in the ratios (parts by mass) shown in the table and kneaded in a Banbury mixer. After curing until the temperature of the mixture reached 80°C or less, the components shown in step (II) in Table 1 were added in the ratios (parts by mass) and kneaded while adjusting the maximum temperature of the mixture to 110°C or less to produce a rubber composition. The rubber composition obtained here was heated at 150°C for 30 minutes using a vulcanizing press to obtain each rubber.

[0085] Tear strength evaluation test The tear strength index of each of the rubber compositions obtained in the above Examples 1 to 9 and Comparative Examples 1 to 4 was measured using a crescent-shaped test piece according to JISK6252 at room temperature and a tensile speed of 500 mm / min. Here, the evaluation results of each Example and Comparative Example were expressed as an index with the value of a rubber composition (Comparative Example 1) prepared with the same compounding contents and the same manufacturing method as each Example except that no compound was added, set to 100, and the tear strength was calculated according to the following formula. Note that a higher tear strength value indicates a better tear strength. Formula: Tear Strength Index = (tear strength of the rubber composition of each of Examples 1 to 9) × 100 / (tear strength of Comparative Example 1) Formula: Tear Strength Index = (tear strength of each of the rubber compositions of Comparative Examples 2 to 4) × 100 / (tear strength of Comparative Example 1)

[0086] [Table 1] *1: Natural rubber; GUANGKEN RUBBER, TSR-20 *2: Compound 1-A: 2-hydrazinyl-2-oxoacetamide produced in Production Example 1 *3: Compound 2-A: Barbituric acid, manufactured by Tokyo Chemical Industry Co., Ltd. *4: Compound 3-A; 2-amino-3-hydroxypropanehydrazide produced in Production Example 2 *5: Compound 4-A; 2-(3-methyl-5-oxo-4,5-dihydro-1H-pyrazol-4-yl)acetohydrazide produced in Production Example 3 *6: Compound 5-A; 4H-1,2,4-triazole-3-carbohydrazide produced in Production Example 4 *7: Compound 6-A; Tokyo Chemical Industry Co., Ltd., 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole *8: Compound 7-A; (3-(pyridin-2-yl)-4H-1,2,4-triazol-4-amine) produced in Production Example 6 *9: Compound 7-B; (2-(pyridin-2-yl)-1,3,4-oxadiazole) produced in Production Example 5 *10: 3-methyl-5-pyrazolone, manufactured by Otsuka Chemical Co., Ltd. *11: Benzoic acid hydrazide, manufactured by Tokyo Chemical Industry Co., Ltd. *12: Oxamide, manufactured by Tokyo Chemical Industry Co., Ltd. *13: 1,2,4-triazole-3-carboxamide, manufactured by Tokyo Chemical Industry Co., Ltd. *14: Carbon black; Cabot Corporation, N234 *15: Antioxidant (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine); manufactured by Kemai Chemical Co., Ltd. *16: Wax; Rhein Chemie Rheinau, Antilux 111 *17: Zinc oxide; manufactured by Dalian Zinc Oxide Co., Ltd. *18: Stearic acid; manufactured by Sichuan Tianyu Grease Co., Ltd. *19: Vulcanization accelerator; N-(tert-butyl)-2-benzothiazolesulfenamide; Sansera NS-G, manufactured by Sanshin Chemical Industry Co., Ltd. *20: Sulfur; manufactured by Shanghai Jinghai Chemical Co., Ltd.

[0087] It was confirmed that when the rubber composition of each Example was used, superior tear strength could be obtained as compared with the case where the rubber composition of each Comparative Example was used. [Industrial Applicability]

[0088] By using the rubber composition of the present invention, a rubber material having high tear strength can be obtained. The rubber composition of the present invention can be suitably used for tires, etc. In addition, the rubber additive of the present invention can impart high tear strength to the rubber material.

Claims

[Claim 1] A tear strength imparting agent for rubber, comprising at least one compound selected from the group consisting of compounds represented by the following (1) to (7) and 3-methyl-5-pyrazolone: 【Chemistry 1】 [In the formula, R group represents a hydrazide group, an N'-alkylidenehydrazide group, an N-allylcarbamoyl group, a 3-carboxylacryloyl group, a hydrazinecarboxyamino group, a thiocarboxyl group, a thiol group, or a hydrogen atom. ４ is a sulfur atom or an oxygen atom. ５ is a thiol group or a hydroxyl group. ６ is an alkylene group having 1 to 4 carbon atoms. ７ R is an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group. ８ is a hydrogen atom or an amino group. ９ is a heteroatom. １０ is a heterocyclic group.

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