Vibration-isolating rubber composition and vibration-isolating rubber member

Abstract

The present invention provides a kind of anti-vibration rubber composition and anti-vibration rubber component, which can satisfy high durability, low elastic force reduction, insulation in high level.All the anti-vibration rubber composition is containing the polymer component consisting of the following (A) component and the following (B) ~ (D) component, wherein, relative to (A) component 100 mass parts, the proportion of (B) component is 0.1 ~ 5 mass parts, the proportion of (C) component is 10 ~ 40 mass parts, the proportion of (D) component is 10 ~ 30 mass parts, and, (C) component is BET specific surface area is 18 ~ 40 m 2 / g component, (A) diene rubber, (B) dihydrazide compound, (C) carbon black, (D) silicon dioxide.

Description

Technical Field

[0001] This invention relates to a vibration-damping rubber composition and a vibration-damping rubber component for use in vehicles such as railway vehicles. Background Technology

[0002] The required functions of vibration damping rubber for railway vehicles include high durability, suppression of elasticity reduction during train operation (low elasticity reduction), and insulation.

[0003] Typically, rubber compositions used as vibration-damping rubbers contain polymers such as diene rubbers, as well as fillers such as silica and carbon black. Rubber compositions using silica as a filler exhibit excellent durability and insulation, but fail to meet properties such as low elasticity reduction. On the other hand, rubber compositions using carbon black as a filler can achieve low elasticity reduction, but their durability and insulation become detrimental.

[0004] In this way, it is difficult to make the anti-vibration rubber composition meet all the requirements of high durability, low elasticity reduction, and insulation in the formulation of filler materials, whether it is silica alone or carbon black alone.

[0005] In addition, research has been conducted in the past on filling materials for the use of silica and carbon black as a mixture in anti-vibration rubber compositions (for example, see Patent Documents 1 to 6).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2017-119873

[0009] Patent Document 2: Japanese Patent Application Publication No. 2015-224279

[0010] Patent Document 3: Japanese Patent Application Publication No. 2018-95810

[0011] Patent Document 4: Japanese Patent Application Publication No. 2016-124880

[0012] Patent Document 5: Japanese Patent No. 6657491

[0013] Patent Document 6: International Publication No. 2015 / 182349 Summary of the Invention

[0014] The problem that the invention aims to solve

[0015] However, the various anti-vibration rubber compositions shown in the aforementioned patent documents do not address all the functional requirements for anti-vibration rubber used in railway vehicles (high durability, low elasticity reduction, insulation) as problems, and in fact, they cannot solve the aforementioned problems.

[0016] That is, in the anti-vibration rubber composition using a mixture of silica and carbon black, the high durability, low elasticity reduction, and insulation properties mentioned above are incompatible characteristics. Therefore, it is currently difficult, even for those skilled in the art, to fully satisfy all these functions. Thus, there is room for improvement in this regard.

[0017] The present invention was made in view of the following circumstances, and provides a vibration damping rubber composition and vibration damping rubber component that can satisfy all the requirements of high durability, low elasticity reduction and insulation at a high level.

[0018] Methods for solving problems

[0019] The inventors of this invention focused on the main reason why the aforementioned problems could not be solved even when silica and carbon black were used together as fillers, and repeatedly studied diene-based rubbers as polymers in anti-vibration rubber compositions. During this research, the following insights were gained: silica has a tendency to agglomerate, and the agglomerated blocks easily disintegrate during vibration of the anti-vibration rubber, thus becoming a major reason for the failure to meet the low elasticity reduction requirement; carbon black lacks chemical bonding at the rubber interface, easily becoming the starting point for cracking, thus becoming a major reason for reduced durability of the anti-vibration rubber; furthermore, carbon black easily forms conductive pathways, thus becoming a major reason for reduced insulation properties of the anti-vibration rubber. Moreover, it was found that these problems cannot be solved by using silica and carbon black together as described above.

[0020] Therefore, the inventors of this invention conceived of using carbon black with a small specific surface area (representing a specific BET specific surface area) as the aforementioned carbon black, and further conceived of adding a dihydrazide compound to improve the dispersibility of the aforementioned carbon black and silica. Moreover, the results of various experiments unexpectedly revealed that by setting the proportions of the aforementioned materials within the specific range specified in this invention, all the functions required for anti-vibration rubber for railway vehicles (high durability, low elasticity reduction, and insulation) can be achieved.

[0021] That is, the present invention takes the following [1] to [6] as its essence.

[0022] [1] A vibration damping rubber composition comprising a polymer component consisting of component (A) and components (B) to (D) thereof, wherein, relative to 100 parts by mass of component (A), component (B) comprises 0.1 to 5 parts by mass, component (C) comprises 10 to 40 parts by mass, component (D) comprises 10 to 30 parts by mass, and component (C) has a BET specific surface area of ​​18 to 40 m². 2 / g of components,

[0023] (A) Diene-based rubber.

[0024] (B) Diacylhydrazide compounds,

[0025] (C) Carbon black,

[0026] (D) Silicon dioxide.

[0027] [2] The anti-vibration rubber composition according to [1] further comprises a silane coupling agent (E).

[0028] [3] According to the vibration damping rubber composition of [2], wherein the silane coupling agent (E) is selected from at least one of the group consisting of mercapto-based silane coupling agents and sulfide-based silane coupling agents.

[0029] [4] The anti-vibration rubber composition according to any one of [1] to [3], wherein the dihydrazide compound (B) is selected from at least one of dihydrazide diacetate and dihydrazide isophthalate.

[0030] [5] A vibration damping rubber component, wherein the vibration damping rubber component is composed of a vulcanizate of any one of the vibration damping rubber compositions described in [1] to [4].

[0031] [6] According to [5], the vibration damping rubber component is a vibration damping rubber component for railway vehicles.

[0032] Invention Effects

[0033] As described above, the vibration-damping rubber composition of the present invention contains a polymer composed of diene-based rubbers, and also contains a dihydrazide compound, carbon black with a BET specific surface area within a specific range, and silica, and the proportions of these components are within a specific range. Therefore, it can satisfy high levels of durability, low elasticity reduction, and insulation. Consequently, it can exhibit excellent performance, especially as a material for vibration-damping rubber used in railway vehicles. Detailed Implementation

[0034] Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to these embodiments.

[0035] As described above, the vibration-damping rubber composition (hereinafter referred to as "this vibration-damping rubber composition"), as an embodiment of the present invention, is a vibration-damping rubber composition containing a polymer component consisting of component (A) and components (B) to (D) described below, wherein, relative to 100 parts by mass of component (A), the proportion of component (B) is 0.1 to 5 parts by mass, the proportion of component (C) is 10 to 40 parts by mass, the proportion of component (D) is 10 to 30 parts by mass, and component (C) has a BET specific surface area of ​​18 to 40 m². 2 / g of components,

[0036] (A) Diene-based rubber.

[0037] (B) Diacylhydrazide compounds,

[0038] (C) Carbon black,

[0039] (D) Silicon dioxide.

[0040] The following is a detailed description of the constituent materials of this vibration-damping rubber composition.

[0041] [Diene-based rubber (A)]

[0042] As described above, this vibration-damping rubber composition uses a polymer composed of diene rubber (A), and does not use polymers other than diene rubber (A). As the diene rubber (A), it is preferable to use a diene rubber with natural rubber (NR) as the main component. Here, "main component" means that 50% by weight or more of the diene rubber (A) is natural rubber, and this also includes cases where the diene rubber (A) is composed entirely of natural rubber. In this way, by using natural rubber as the main component, it becomes superior in terms of strength and low dynamic rate capability.

[0043] In addition, diene-based rubbers other than natural rubber include, for example, butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), isoprene rubber (IR), acrylonitrile-butadiene rubber (NBR), ethylene-propylene-diene rubber (EPDM), butyl rubber (IIR), and chloroprene rubber (CR). These can be used alone or in combination with two or more other types. It is desirable to use these diene-based rubbers in combination with natural rubber.

[0044] [Diacylhydrazide compound (B)]

[0045] As previously stated, this anti-vibration rubber composition contains a dihydrazide compound (B) in a specific proportion. Examples of dihydrazide compounds (B) include those represented by the general formula (1) below.

[0046] [Compound 1]

[0047]

[0048] [In the above general formula (1), R represents an alkylene group having 1 to 30 carbon atoms, a cycloalkylene group having 1 to 30 carbon atoms, or a phenylene group.]

[0049] Specific examples of the aforementioned dihydrazide compound (B) include adipic acid dihydrazide, isophthalic acid dihydrazide, phthalic acid dihydrazide, terephthalic acid dihydrazide, succinic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, oxalic acid dihydrazide, and dodecanoic acid dihydrazide. These can be used alone or in combination of two or more. From the viewpoint of low dynamic rate control, adipic acid dihydrazide and isophthalic acid dihydrazide are preferred.

[0050] From the viewpoint of achieving the effects of the present invention (to satisfy all the requirements of high durability, low elasticity reduction, and insulation at a high level), as mentioned above, the content of the diacylhydrazine compound (B) is 0.1 to 5 parts by mass relative to 100 parts by mass of the diene rubber (A), and from the same viewpoint, preferably 0.5 to 4 parts by mass, more preferably 0.75 to 3 parts by mass.

[0051] [Carbon black (C)]

[0052] Furthermore, as mentioned above, this vibration-damping rubber composition contains carbon black (C) in a specific proportion. The carbon black (C) used has a BET specific surface area of ​​18–40 m². 2 / g carbon black. Preferably, a BET specific surface area of ​​18-35m² is used. 2 Carbon black with a density of / g is preferred, preferably carbon black with a BET specific surface area of ​​18-30m². 2 / g of carbon black.

[0053] That is, this is because of the following problem: if the BET specific surface area of ​​the carbon black (C) is too large, the desired insulation effect cannot be obtained; if the BET specific surface area is too small, the durability is reduced.

[0054] Furthermore, the BET specific surface area of ​​the aforementioned carbon black (C) can be measured, for example, by degassing the sample at 200°C for 15 minutes, using a mixed gas (N2: 70%, He: 30%) as the adsorbent gas, and then by using a BET specific surface area measuring device (manufactured by Micro Data Corporation, 4232-II).

[0055] From the perspective of reinforcement, durability, and insulation, various grades of carbon black (C) can be used, including FEF, MAF, GPF, SRF, FT, and MT grades. These can be used alone or in combination of two or more. Among these, from the above perspective, FEF grade carbon black is preferred.

[0056] From the viewpoint of achieving the effects of the present invention (to satisfy all the requirements of high durability, low elasticity reduction, and insulation at a high level), as mentioned above, the content of the carbon black (C) is 10 to 40 parts by mass relative to 100 parts by mass of the diene rubber (A), and from the same viewpoint, preferably 20 to 40 parts by mass, more preferably 30 to 40 parts by mass.

[0057] [Silicon dioxide (D)]

[0058] Furthermore, as mentioned above, this vibration-damping rubber composition contains silica (D) in a specific proportion. For example, wet silica, dry silica, colloidal silica, etc., can be used as the silica (D). Moreover, these can be used alone or in combination of two or more.

[0059] Furthermore, from the viewpoint of balancing high durability and low elasticity reduction, the BET specific surface area of ​​the aforementioned silica (D) is preferably 20–380 m². 2 / g, more preferably with a BET specific surface area of ​​30-330m² 2 / g of silicon dioxide.

[0060] Furthermore, the BET specific surface area of ​​the aforementioned silica (D) can be measured, for example, by degassing the sample at 200°C for 15 minutes, using a mixed gas (N2: 70%, He: 30%) as the adsorbent gas, and then by using a BET specific surface area measuring device (manufactured by Micro Data Corporation, 4232-II).

[0061] From the viewpoint of achieving the effects of the present invention (to satisfy all aspects of high durability, low elasticity reduction, and insulation at a high level), as mentioned above, the content of the silica (D) is 10 to 30 parts by mass relative to 100 parts by mass of the diene rubber (A), and from the same viewpoint, preferably 15 to 30 parts by mass, more preferably 20 to 30 parts by mass.

[0062] [Silane coupling agent (E)]

[0063] This vibration-damping rubber composition may contain a silane coupling agent (E) as needed. In this way, by containing a silane coupling agent (E) in this vibration-damping rubber composition, the silica (D) and diene rubber (A) are bonded via the silane coupling agent (E), thereby further improving the durability of the vibration-damping rubber.

[0064] As the aforementioned silane coupling agent (E), for example, two or more mercapto-based silane coupling agents, sulfide-based silane coupling agents, amine-based silane coupling agents, epoxy-based silane coupling agents, vinyl-based silane coupling agents, etc., can be used alone or in combination. Among them, if the aforementioned silane coupling agent is a mercapto-based silane coupling agent or a sulfide-based silane coupling agent, the vulcanization density is increased, which is particularly effective for low dynamic rate and durability, and is therefore preferred.

[0065] Examples of mercaptosilane coupling agents include 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane. These can be used alone or in combination of two or more.

[0066] Examples of sulfide-based silane coupling agents include bis-(3-(triethoxysilyl)-propyl)-disulfide, bis(3-triethoxysilylpropyl)trisulfide, bis-(3-(triethoxysilyl)-propyl)-tetrasulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, and 3-trimethoxysilylpropyl-N,N-dimethylthioamino. Formyl tetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, etc. These can be used alone or in combination of two or more.

[0067] Examples of amine-based silane coupling agents include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and 3-(N-phenyl)aminopropyltrimethoxysilane. These can be used alone or in combination of two or more.

[0068] Examples of epoxy-based silane coupling agents include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyltriethoxysilane, and 3-epoxypropoxypropylmethyldiethoxysilane. These can be used alone or in combination of two or more.

[0069] Examples of vinyl-based silane coupling agents include vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyldimethylchlorosilane, vinyltrichlorosilane, vinyltriisopropoxysilane, and vinyltri(2-methoxyethoxy)silane. These can be used alone or in combination of two or more.

[0070] From the perspective of excellent properties such as low dynamic ratio and durability, the content of these silane coupling agents (E) is preferably 0.1 to 10 parts by mass relative to 100 parts by mass of the diene rubber (A), and more preferably in the range of 0.3 to 8 parts by mass.

[0071] In addition, this vibration-damping rubber composition may contain, as needed, components (A) to (D) as essential components, components (E), vulcanizing agents, vulcanization accelerators, vulcanization aids, anti-aging agents, processing oils, etc.

[0072] Examples of sulfur-containing compounds include sulfur (powdered sulfur, precipitated sulfur, insoluble sulfur), alkylphenol disulfides, etc. These can be used alone or in combination of two or more.

[0073] Furthermore, relative to 100 parts by weight of the diene rubber (A), the content of the vulcanizing agent is preferably in the range of 0.1 to 10 parts by weight, and particularly preferably in the range of 0.3 to 5 parts by weight. This is because if the content of the vulcanizing agent (E) is too low, a tendency for decreased vulcanization reactivity can be observed; conversely, if the content of the vulcanizing agent (E) is too high, a tendency for decreased rubber properties (breaking strength, elongation at break) can be observed.

[0074] Examples of vulcanization accelerators include thiuram-based, sulfenamide-based, guanidine-based, thiazole-based, aldehyde-amine-based, thiourea-based, and other vulcanization accelerators. These can be used alone or in combination of two or more. Among them, from the perspective of improving compression set, a vulcanization accelerator that combines a thiuram-based vulcanization accelerator with a vulcanization accelerator selected from at least one of sulfenamide-based, guanidine-based, and thiazole-based accelerators is preferred.

[0075] Furthermore, relative to 100 parts by weight of the diene rubber (A) mentioned above, the content of the vulcanization accelerator is preferably in the range of 0.1 to 10 parts by weight, and particularly preferably in the range of 0.3 to 5 parts by weight.

[0076] Examples of thiuram-based vulcanization accelerators include tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), tetrabutylthiuram disulfide (TBTD), tetra(2-ethylhexyl)thiuram disulfide (TOT), and tetrabenzylthiuram disulfide (TBzTD). These can be used alone or in combination of two or more.

[0077] Examples of sulfenamide-based vulcanization accelerators include N-oxadiethylene-2-benzothiazole sulfenamide (NOBS), N-cyclohexyl-2-benzothiazole sulfenamide (CBS), N-tert-butyl-2-benzothiazole sulfenamide (BBS), and N,N'-dicyclohexyl-2-benzothiazole sulfenamide. These can be used alone or in combination of two or more.

[0078] Examples of guanidine-based vulcanization accelerators include N,N'-diphenylthiourea, trimethylthiourea, N,N'-diethylthiourea, and N,N'-dibutylthiourea. These can be used alone or in combination of two or more.

[0079] Examples of thiazole-based vulcanization accelerators include dibenzothiazole disulfide (MBTS), 2-mercaptobenzothiazole (MBT), sodium 2-mercaptobenzothiazole (NaMBT), and zinc 2-mercaptobenzothiazole (ZnMBT). These can be used alone or in combination of two or more. Among them, dibenzothiazole disulfide (MBTS) and 2-mercaptobenzothiazole (MBT) are preferred, especially considering their superior vulcanization reaction characteristics.

[0080] Examples of vulcanizing aids mentioned above include zinc oxide (ZnO), stearic acid, and magnesium oxide. These can be used alone or in combination of two or more.

[0081] Furthermore, relative to 100 parts by weight of the diene rubber (A) mentioned above, the content of the vulcanizing aid is preferably in the range of 0.1 to 10 parts by weight, and particularly preferably in the range of 0.3 to 7 parts by weight.

[0082] Examples of anti-aging agents mentioned above include carbamate-based anti-aging agents, phenylenediamine-based anti-aging agents, phenolic anti-aging agents, diphenylamine-based anti-aging agents, quinoline-based anti-aging agents, imidazole-based anti-aging agents, and waxes. These can be used alone or in combination of two or more.

[0083] In addition, relative to 100 parts by weight of the diene rubber (A) mentioned above, the content of the anti-aging agent is preferably in the range of 0.5 to 15 parts by weight, and particularly preferably in the range of 1 to 10 parts by weight.

[0084] Examples of oils used in the aforementioned processes include cycloalkanes, paraffins, and aromatics. These can be used alone or in combination of two or more.

[0085] In addition, relative to 100 parts by weight of the diene rubber (A) mentioned above, the content of the above-mentioned processing oil is preferably in the range of 1 to 35 parts by weight, and particularly preferably in the range of 3 to 30 parts by weight.

[0086] [Preparation method of vibration-damping rubber composition]

[0087] Here, this vibration-damping rubber composition can be prepared by mixing components (A) to (D) as essential components in a specific ratio, and further, by using component (E) as required, and other materials listed above, using a mixing machine such as a kneader, a Banbury mixer, an open roller mixer, or a twin-screw mixer.

[0088] In particular, it is desirable to perform the above-mentioned mixing by the following method: mixing materials other than vulcanizing agent and vulcanization accelerator at 100-170°C for 3-10 minutes (preferably, mixing at 120-150°C for 3-5 minutes) using a Banbury internal mixer, and then mixing the vulcanizing agent and vulcanization accelerator with open rollers at 30-80°C for 3-10 minutes (preferably, mixing at 30-60°C for 3-5 minutes).

[0089] Furthermore, from the viewpoint of obtaining the effects of the present invention (to satisfy all of the following: high durability, low elasticity reduction, and insulation), the vibration damping rubber composition obtained as described above preferably satisfies the following condition (α).

[0090] (α) The ΔG' shown in Equation (I) below is 5.0 or less.

[0091] ΔG'=G'1 / G'2……(I)

[0092] [In formula (I), G'1 is the storage elasticity of the uncured rubber composition at a frequency of 11 Hz, a deflection angle of 0.28%, and a temperature of 40°C, and G'2 represents the storage elasticity of the uncured rubber composition at a frequency of 11 Hz, a deflection angle of 42%, and a temperature of 40°C.]

[0093] Furthermore, from the viewpoint of obtaining the desired effect of the present invention, ΔG' is preferably 4.5 or less.

[0094] Furthermore, according to Japanese Patent Application Publication No. 2006-47070, ΔG' shown in the above formula (I) is a numerical value used to evaluate the cohesiveness of fillers; the smaller ΔG' is, the higher the dispersibility of the filler. Additionally, G'1 and G'2 can be measured, for example, using a rubber processing testing machine, a vulcanizer, or a dynamic viscoelasticity tester. More specifically, they can be measured using the RPA2000 manufactured by Alpha Technology.

[0095] Furthermore, this vibration-damping rubber composition becomes a vibration-damping rubber component (vulcanizate) by vulcanizing at a high temperature (150-170°C) for 5-30 minutes.

[0096] The surface hardness (JIS-A hardness) of the aforementioned vibration-damping rubber component (vulcanizate) is typically 60 to 85, preferably 65 to 80. Furthermore, this hardness can be measured using an ASKER rubber hardness tester (P1-A type) manufactured by Polymer Instruments Co., Ltd.

[0097] Furthermore, the aforementioned vibration-damping rubber component (vulcanizate) exhibits a fracture resistance of over 80,000 cycles in a tensile fatigue test conducted according to JIS K 6260. Preferably, the vibration-damping rubber component exhibits a fracture resistance of over 100,000 cycles, and more preferably, it exhibits a fracture resistance of over 120,000 cycles.

[0098] Furthermore, the volume resistivity of the aforementioned vibration-damping rubber component (vulcanizate), measured according to JIS K 6271-1:2015 (vulcanized rubber and thermoplastic rubber—method of resistivity determination), reaches 1×10⁻⁶ under the following conditions. 9 Ω·cm or higher. Preferably, the volume resistivity can reach 1×10⁻⁶. 11 Vibration-damping rubber components with a resistivity of Ω·cm or higher are more preferably those with a volume resistivity of 1×10⁻⁶. 13 Vibration-damping rubber components with an Ω·cm or higher.

[0099] Measurement method: Double ring electrode method

[0100] Protective electrode: outer diameter 80mm, inner diameter 70mm

[0101] Main electrode: 50mm

[0102] External dimensions of the sample: 100mm × 100mm

[0103] Sample thickness: 2mm

[0104] Applied voltage: 1V

[0105] Detection current range: 200pA~20mA

[0106] Furthermore, the elasticity reduction value of the aforementioned anti-vibration rubber component (vulcanizate) as shown in Formula (II) below can reach -20% or more, preferably an anti-vibration rubber component with an elasticity reduction value of -18% or more, and more preferably an anti-vibration rubber component with an elasticity reduction value of -16% or more. The elasticity reduction value shown in Formula (II) below is obtained by the following method: performing a durability fatigue test at a frequency of 3Hz, repeatedly stretching and contracting 4mm in the compression direction and 15mm in the tension direction, and measuring the load at the 15mm tension (initial load F1, and load F2 after 3000 stretching cycles).

[0107] Elasticity reduction = {(F2-F1) / F1}×100 (%)……(II)

[0108] As described above, the anti-vibration rubber component made of the vulcanizate of this anti-vibration rubber composition can meet all the requirements of high durability, low elasticity reduction and insulation at a high level. Therefore, it can perform excellently as a material for anti-vibration rubber for railway vehicles.

[0109] In addition to the above-mentioned uses, it can also be used as a component in motor vehicles such as engine mounts, stabilizer bushings, suspension bushings, motor mounts, and subframe mounts. Due to its high insulation properties, it is also advantageously used as a component in electric vehicles powered by electric motors (including fuel cell vehicles (FCVs), plug-in hybrid vehicles (PHVs), and hybrid vehicles (HVs) in the form of motor mounts, suspension bushings, and subframe mounts) (vibration damping rubber components for electric vehicles).

[0110] In addition, due to its high insulation properties, it can also be used as a vibration damper for computer hard drives, a vibration damper for general household appliances such as washing machines, a vibration damping wall for buildings in the construction and residential field, a vibration damping device, and a seismic isolation device.

[0111] Example

[0112] Next, the embodiments will be described together with comparative examples. However, the present invention is not limited to these embodiments.

[0113] First, prior to the examples and comparative examples, the following materials were prepared. Furthermore, the measured values ​​for carbon black and silica were determined according to the methods described above.

[0114] [Natural Rubber (NR)]

[0115] [Dihydrazide(i)]

[0116] Manufactured by Otsuka Chemical Co., Ltd., Adipate dihydrazide (ADH)

[0117] [Diacylhydrazide(ii)]

[0118] Manufactured by Otsuka Chemical Co., Ltd., IDH (Isophthalic Acid Dihydrazide)

[0119] [Carbon black(i)]

[0120] Manufactured by Tokai Carbon Co., Ltd., SeastV (BET specific surface area of ​​27m²) 2 / g)

[0121] [Carbon black (ii)]

[0122] Manufactured by Asahi Carbon, Asahi #60 (BET specific surface area of ​​40m²) 2 / g)

[0123] [Carbon black (iii)]

[0124] Manufactured by Tokai Carbon Co., Ltd., Seast SRA (BET specific surface area of ​​18m²) 2 / g)

[0125] [Carbon black (iv)]

[0126] Manufactured by Cabotcorp Japan, SHOWBLACK N330 (BET specific surface area 75m²) 2 / g)

[0127] [Carbon black (v)]

[0128] Manufactured by Asahi Carbon, Asahi #15 (BET specific surface area of ​​12m³) 2 / g)

[0129] [Carbon black (vi)]

[0130] Manufactured by Asahi Carbon, Asahi #65 (BET specific surface area 42m²) 2 / g)

[0131] [Silicon dioxide]

[0132] Nipsil VN3 (BET specific surface area 180-230 m²) manufactured by Tosoh Silica Co., Ltd. 2 / g)

[0133] [Silane coupling agent (i)]

[0134] Sulfide-based silane coupling agent (manufactured by EVONIK DEGUSSA, Si-69)

[0135] [Silane coupling agent (ii)]

[0136] Thiol-based silane coupling agent (manufactured by MOMENTIVE, NXT Z45)

[0137] [Zinc oxide]

[0138] Two types of zinc oxide manufactured by Sakai Chemical Industry Co., Ltd.

[0139] [Stearic acid]

[0140] Sakura Beaded Stearic Acid, manufactured by Nippon Oil Company

[0141] [Anti-aging agents]

[0142] Antigene 6C manufactured by Sumitomo Chemical Co., Ltd.

[0143] [Oil]

[0144] Manufactured by Japan Taiyo Oil Co., Ltd., SUNTHENE 410

[0145] [Vulcanization accelerator]

[0146] Manufactured by Sanxin Chemical Industry Co., Ltd., Sanceler CZ-G

[0147] [Sulfur (Vulcanizing Agent)]

[0148] Karuizawa Smelting Co., Ltd.

[0149] [Examples 1 to 13, Comparative Examples 1 to 9]

[0150] The above materials were combined and mixed in the proportions shown in Tables 1 and 2 below to prepare a vibration-damping rubber composition. Furthermore, the above mixing was performed as follows: First, materials other than the vulcanizing agent and vulcanization accelerator were mixed at 140°C for 5 minutes using a Banbury internal mixer; then, the vulcanizing agent and vulcanization accelerator were combined and mixed at 60°C for 5 minutes using open rollers.

[0151] The vibration-damping rubber compositions of the examples and comparative examples thus obtained were evaluated according to the following criteria. The results are shown in Tables 1 and 2 below.

[0152] <ΔG'>

[0153] For each vibration-damping rubber composition, the storage elasticity of the uncured rubber composition at a frequency of 11 Hz and a temperature of 40°C was measured using an RPA2000 (manufactured by Alpha Technology) (storage elasticity G'1 at a deflection angle of 0.28% and storage elasticity G'2 at a deflection angle of 42%). Then, based on the above measurement results, ΔG' as shown in the following formula (I) was calculated.

[0154] ΔG'=G'1 / G'2……(I)

[0155] <Enhancement>

[0156] Each vibration-damping rubber composition was stamped (vulcanized) at 150°C for 30 minutes, and the hardness (JIS-A hardness) of its rubber surface was measured using an ASKER rubber hardness tester (P1-A type) (manufactured by Polymer Instruments Co., Ltd.). Then, the reinforcement was evaluated according to the following criteria.

[0157] 〇 (Very good): Hardness is 60 or higher.

[0158] × (Poor): Hardness less than 60.

[0159] <Durability>

[0160] Each vibration-damping rubber composition was stamped (vulcanized) at 150°C for 30 minutes to produce a rubber sheet with a thickness of 2 mm. Then, a JIS No. 3 dumbbell was punched from the rubber sheet, and the dumbbell was used to conduct a tensile fatigue test according to JIS K6260.

[0161] Then, the number of expansion and contraction cycles at fracture was measured, and the durability was evaluated according to the following criteria.

[0162] ○ (Very good): More than 80,000 times of expansion and contraction.

[0163] × (Poor): The number of times the device has been stretched is less than 80,000.

[0164] <Insulation>

[0165] For samples obtained by stamping (vulcanizing) each vibration damping rubber composition at 150°C for 30 minutes, the volume resistivity VR (Ω·cm) was measured according to JIS K 6271-1:2015 (vulcanized rubber and thermoplastic rubber - method for determining resistivity).

[0166] Specifically, the volume resistivity VR was determined under the following conditions.

[0167] Measurement method: Double ring electrode method

[0168] Protective electrode: outer diameter 80mm, inner diameter 70mm

[0169] Main electrode: 50mm

[0170] External dimensions of the sample: 100mm × 100mm

[0171] Sample thickness: 2mm

[0172] Applied voltage: 1V

[0173] Detection current range: 200pA~20mA

[0174] Then, the insulation performance was evaluated according to the following criteria.

[0175] 〇 (Excellent): Volume resistivity VR is 1×10 9 Ω·cm or higher.

[0176] ×(difference): Volume resistivity VR is less than 1×10 9 Ω·cm.

[0177] <Reduced elasticity>

[0178] For vibration-damping rubber samples obtained by stamping (vulcanizing) various vibration-damping rubber compositions at 150°C for 30 minutes, a durability fatigue test was conducted at a frequency of 3 Hz, involving repeated stretching and contraction of 4 mm in the compression direction and 15 mm in the stretching direction. The load at the 15 mm stretch (initial load F1 and load F2 after 3000 stretching cycles) was measured. Then, based on the above test results, the elasticity reduction property shown in Equation (II) below was calculated.

[0179] Elasticity reduction = {(F2-F1) / F1}×100 (%)……(II)

[0180] Then, the elasticity reduction was evaluated based on the following criteria.

[0181] 〇 (Very good): Elasticity reduction is more than -20%.

[0182] × (Poor): Elasticity reduction is less than -20%.

[0183] Table 1 (Parts by weight)

[0184]

[0185] Table 2 (Parts by weight)

[0186]

[0187] Based on the results in Tables 1 and 2 above, the vulcanizates of the anti-vibration rubber compositions of the embodiments exhibit the properties required by the present invention in all aspects of durability (high durability), elasticity reduction (low elasticity reduction), and insulation.

[0188] In contrast, the vibration-damping rubber composition of Comparative Example 1, due to its insufficient content of dihydrazide compound and inadequate dispersion of carbon black, resulted in the formation of conductive pathways and poor insulation. Furthermore, the insufficient dispersion of carbon black and silica led to the formation of agglomerates, which, during durable vibration, shattered, causing a decrease in load and resulting in poor elasticity reduction.

[0189] The vibration-damping rubber composition of Comparative Example 2 had poor durability due to the excessive content of dihydrazide compound and the significantly increased viscosity of the rubber.

[0190] The anti-vibration rubber composition of Comparative Example 3 had too little carbon black content, resulting in poor reinforcement (hardness).

[0191] The anti-vibration rubber composition of Comparative Example 4 had an excessive amount of carbon black, which resulted in poor insulation due to the formation of conductive pathways.

[0192] The vibration damping rubber composition of Comparative Example 5 resulted in poor insulation because the BET specific surface area of ​​its carbon black exceeded the value specified in this invention, and the conductivity increased with the increase in surface area.

[0193] The vibration damping rubber composition of Comparative Example 6 exhibits poor durability because the BET specific surface area of ​​its carbon black is smaller than the value specified in this invention, and the interface between the rubber and carbon black is prone to become the starting point for cracking during durable vibration.

[0194] The anti-vibration rubber composition of Comparative Example 7 had too little silica, resulting in poor reinforcement (hardness).

[0195] The vibration damping rubber composition of Comparative Example 8 has poor elasticity due to its excessive silica content and the reduction in load caused by the agglomeration of silica particles during durable vibration.

[0196] The vibration damping rubber composition of Comparative Example 9 resulted in poor insulation because the BET specific surface area of ​​its carbon black exceeded the value specified in this invention, and the conductivity increased with the increase in surface area.

[0197] The above embodiments illustrate specific aspects of the present invention, but these embodiments are merely examples and are not intended to be limiting. Various modifications that are apparent to those skilled in the art are intended to be included within the scope of the present invention.

[0198] Industrial applicability

[0199] The anti-vibration rubber components made from the vulcanizates of this anti-vibration rubber composition can meet all the requirements of high durability, low elasticity reduction and insulation at a high level. Therefore, they can perform excellently as materials for anti-vibration rubber in railway vehicles.

[0200] In addition to the above-mentioned uses, it can also be used as a component in motor vehicles such as engine mounts, stabilizer bushings, suspension bushings, motor mounts, and subframe mounts. Due to its high insulation properties, it is also advantageously used as a component in electric vehicles powered by electric motors (including fuel cell vehicles (FCVs), plug-in hybrid vehicles (PHVs), and hybrid vehicles (HVs) in the form of motor mounts, suspension bushings, and subframe mounts) (vibration damping rubber components for electric vehicles).

[0201] In addition, due to its high insulation properties, it can also be used as a vibration damper for computer hard drives, a vibration damper for general household appliances such as washing machines, a vibration damping wall for buildings in the construction and residential field, a vibration damping device, and a seismic isolation device.

Claims

1. A vibration-damping rubber composition comprising a polymer component consisting of component (A) and components (B) to (D) thereof, wherein, Compared to 100 parts by mass of component (A), the proportion of component (B) is 0.1-5 parts by mass, the proportion of component (C) is 20-40 parts by mass, and the proportion of component (D) is 10-30 parts by mass. Furthermore, component (C) has a BET specific surface area of ​​18-40 m². 2 / g of components, (A) Diene-based rubber, (B) Diacylhydrazide compounds, (C) Carbon black, (D) Silicon dioxide.

2. The vibration-damping rubber composition according to claim 1, wherein, The vibration damping rubber composition also contains a silane coupling agent (E).

3. The vibration-damping rubber composition according to claim 2, wherein, The silane coupling agent (E) is selected from at least one of the group consisting of mercapto-based silane coupling agents and sulfide-based silane coupling agents.

4. The anti-vibration rubber composition according to any one of claims 1 to 3, wherein, The dihydrazide compound (B) is selected from at least one of azidodiacid dihydrazide and isophthalic acid dihydrazide.

5. A vibration-damping rubber component, wherein, The vibration-damping rubber component is composed of a vulcanizate of the vibration-damping rubber composition according to any one of claims 1 to 4.

6. The vibration-damping rubber component according to claim 5, wherein, The vibration-damping rubber component is a vibration-damping rubber component used in railway vehicles.

Images