Flame-retardant vibration-proof rubber composition and flame-retardant vibration-proof rubber member

Abstract

A flame-retardant vibration-damping rubber composition comprising (A) to (D) thereof, wherein, relative to 100 parts by mass of (A), the proportion of (B) is 20 to 150 parts by mass, the proportion of (C) is 0.01 to 5.0 parts by mass, and the proportion of (D) is 10 to 80 parts by mass. This provides a flame-retardant vibration-damping rubber composition and flame-retardant vibration-damping rubber components that maintain flame retardancy while exhibiting excellent rubber properties, dynamic ratio, and other vibration-damping rubber characteristics. (A) Diene rubber. (B) Metal hydroxide. (C) Diacylhydrazine compound. (D) Carbon black.

Description

Technical Field

[0001] This invention relates to flame-retardant vibration-damping rubber compositions and flame-retardant vibration-damping rubber components for vibration damping applications in vehicles such as motor vehicles and trams. Background Technology

[0002] Vibration-damping rubber components are typically used in motor vehicles and railway vehicles to reduce vibration and noise. For these components, a low dynamic ratio (reducing the value of the dynamic spring constant (Kd) / static spring constant (Ks)) is required to improve noise reduction. In addition to vibration-damping properties such as low dynamic ratio, flame retardancy is sometimes also required for these components. Regarding flame retardancy of rubber, methods include adding halogen-based flame retardants, phosphorus-based flame retardants, metal hydroxides, etc. (see, for example, Patent Document 1 and Patent Document 2).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 7-166047

[0006] Patent Document 2: Japanese Patent No. 5847262 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, if flame retardancy is desired by adding flame retardants as described above, a deterioration in rubber properties and dynamic ratio is sometimes observed. For example, when using aluminum hydroxide as a flame retardant, a large amount of aluminum hydroxide needs to be added to fully express its flame retardancy, which leads to a deterioration in rubber properties and dynamic ratio.

[0009] In the aforementioned Patent Document 2, the applicant has developed the following technology: In order to improve the physical properties of rubber and increase the dynamic ratio while maintaining the flame retardant effect, a specific amount of a low-melting-point halogenated flame retardant and small-particle-size aluminum hydroxide is combined with the diene rubber of the polymer used as the anti-vibration rubber composition. However, even with this technology, there is still room for improvement.

[0010] The present invention was made in view of the following circumstances, and provides a flame-retardant vibration-damping rubber composition and a flame-retardant vibration-damping rubber component that have excellent rubber properties, dynamic ratio and other vibration-damping rubber characteristics while maintaining flame retardancy.

[0011] means for solving problems

[0012] The main idea of ​​this invention is as follows [1] to [5].

[0013] [1] A flame-retardant vibration-damping rubber composition comprising (A) to (D) below, wherein, relative to 100 parts by weight of (A) below, the proportion of (B) below is 20 to 150 parts by weight, the proportion of (C) below is 0.01 to 5.0 parts by weight, and the proportion of (D) below is 10 to 80 parts by weight.

[0014] (A) Diene-based rubber.

[0015] (B) Metal hydroxides,

[0016] (C) Diacylhydrazide compounds,

[0017] (D) Carbon black.

[0018] [2] According to the flame-retardant vibration-damping rubber composition of [1], wherein the metal hydroxide (B) is at least one selected from aluminum hydroxide and magnesium hydroxide.

[0019] [3] The flame-retardant and vibration-damping rubber composition according to [1] or [2], wherein the dihydrazide compound (C) is at least one of dihydrazide diacetate and dihydrazide isophthalic acid.

[0020] [4] The flame-retardant vibration-damping rubber composition according to any one of [1] to [3], wherein the carbon black (D) has a DBP oil absorption of 10 to 180 ml / 100 g and an iodine adsorption of 10 to 200 mg / g.

[0021] [5] A flame-retardant vibration-damping rubber component, wherein the flame-retardant vibration-damping rubber component is formed from a vulcanizate of any one of [1] to [4].

[0022] In conventional flame-retardant vibration-damping rubbers, a large amount of metal hydroxide is required to achieve flame retardancy, resulting in poor dispersion of the metal hydroxide and deterioration of rubber properties and vibration-damping rubber characteristics such as dynamic ratio. Therefore, the inventors of this invention have conducted extensive research to solve these problems, investigating methods to improve rubber properties and vibration-damping rubber characteristics (low dynamic ratio) even when metal hydroxide is used in diene-based rubbers used as the vibration-damping rubber polymer. As a result of repeated experiments, it was found that using dihydrazide compounds and carbon black is effective in improving the dispersibility of metal hydroxides. Furthermore, by including the aforementioned materials in specific proportions, it is possible to improve vibration-damping rubber characteristics while maintaining flame retardancy.

[0023] The reasons for achieving the above effects can be speculated as follows: Diacylhydrazine compounds exhibit the effect of increasing the crosslinking density of rubber and improving rubber viscosity. Therefore, applying shear during rubber compounding can improve the dispersibility of metal hydroxides in the rubber. Furthermore, the interaction between the polar diacylhydrazine and the hydroxyl groups of the metal hydroxide can further promote this dispersibility. In addition, carbon black, with its wide specific surface area and complex microstructure, also possesses a chemically active surface (containing functional groups such as hydroxyl and carboxyl groups), making it highly reactive with rubber molecular chains and thus exhibiting high reinforcing properties. Therefore, by adding carbon black and applying shear during rubber compounding, the dispersibility of metal hydroxides in the rubber can be further improved.

[0024] Furthermore, by combining metal hydroxides, dihydrazides, and carbon black in specific proportions relative to the diene-based rubber used as the anti-vibration rubber, it is possible to achieve improved dispersibility due to the interaction between the dihydrazide and metal hydroxide, and improved dispersibility of the metal hydroxide based on the shear rise during mixing caused by the dihydrazide and carbon black. Therefore, the desired anti-vibration rubber properties can be obtained. Moreover, neither the dihydrazide nor carbon black alone can sufficiently achieve the aforementioned effects. Additionally, even when using a monohydrazide instead of a dihydrazide, the dispersibility of both metal hydroxide and carbon black can be improved. However, since the dihydrazide is highly reactive, the improved dispersibility of both metal hydroxide and carbon black further enhances the anti-vibration rubber properties.

[0025] Invention Effects

[0026] As can be seen from the above, the flame-retardant vibration-damping rubber composition of the present invention exhibits excellent flame retardancy and provides superior vibration-damping rubber properties such as rubber physical properties and dynamic ratio. Furthermore, the flame-retardant vibration-damping rubber composition of the present invention is suitable for use as a material for vibration-damping rubber components requiring flame retardancy, such as engine mounts, stabilizer bushings, suspension bushings, etc., used in motor vehicles and trams, as well as vibration-damping rubber components in the construction and residential fields. Detailed Implementation

[0027] Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to these embodiments.

[0028] As described above, the flame-retardant vibration-damping rubber composition (hereinafter referred to as "this vibration-damping rubber composition"), as an embodiment of the present invention, contains the following (A) to (D) in a specific proportion:

[0029] (A) Diene-based rubber.

[0030] (B) Metal hydroxides,

[0031] (C) Diacylhydrazide compounds,

[0032] (D) Carbon black.

[0033] [Diene-based rubber (A)]

[0034] Examples of diene-based rubbers (A) used in this vibration-damping rubber composition include, for example, natural rubber (NR), 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 of two or more. From the viewpoint of strength and low dynamic range, natural rubber is preferred.

[0035] [Metal hydroxide (B)]

[0036] Aluminum hydroxide and magnesium hydroxide are preferred as the metal hydroxide (B). Furthermore, two or more of the aforementioned metal hydroxide (B) can be used alone or in combination. Moreover, especially from the viewpoint of rubber properties, the aforementioned metal hydroxide (B) is preferably a metal hydroxide with an average particle size of 2 μm or less, more preferably a metal hydroxide with an average particle size of 1.5 μm or less, and particularly preferably a metal hydroxide with an average particle size of 1.1 μm or less. That is, by uniformly dispersing such a small-particle-size metal hydroxide with a large surface area, superior rubber properties can be obtained. Furthermore, the average particle size of the aforementioned metal hydroxide (B) is the volume average particle size, which can be derived, for example, by measuring a sample arbitrarily extracted from the parent group using a laser diffraction scattering particle size distribution measuring device.

[0037] The amount of the metal hydroxide (B) is 20 to 150 parts by mass relative to 100 parts by mass of the diene rubber (A), preferably 20 to 80 parts by mass. This is because if the amount of the metal hydroxide (B) is too small, the desired flame retardancy cannot be obtained; conversely, if the amount of the metal hydroxide (B) is too large, the rubber properties will be reduced.

[0038] [Diacylhydrazide compound (C)]

[0039] The aforementioned dihydrazide compound (C) is used to improve the dispersibility of metal hydroxide (B) and carbon black (D). Moreover, as the aforementioned dihydrazide compound (C), the dihydrazide compound represented by the following general formula (1) is preferably used.

[0040] [Chemistry 1]

[0041]

[0042] [In the above general formula (1), R represents an alkylene group having 1 to 30 carbon atoms, a cycloalkylene group having 3 to 30 carbon atoms, or a phenylene group.]

[0043] In the above general formula (1), R is preferably an alkylene or phenylene with 4 to 12 carbon atoms.

[0044] Furthermore, specific examples of the aforementioned dihydrazide compound (C) include, for instance, 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 high dispersibility of the metal hydroxide (B) and carbon black (D), adipic acid dihydrazide and isophthalic acid dihydrazide are preferred.

[0045] From the viewpoint of the high dispersibility of metal hydroxide (B) and carbon black (D), the content of the dihydrazide compound (C) is 0.01 to 5.0 parts by mass relative to 100 parts by mass of the diene rubber (A), preferably 0.1 to 5.0 parts by mass, and more preferably 0.3 to 3.0 parts by mass.

[0046] [Carbon Black (D)]

[0047] As for the aforementioned carbon black (D), various grades of carbon black can be used, such as SAF, ISAF, HAF, MAF, FEF, GPF, SRF, FT, and MT. These can be used alone or in combination of two or more. From the viewpoint of vibration characteristics and fatigue resistance, FEF grade carbon black is preferred.

[0048] Furthermore, from the viewpoints of durability, low dynamic range, and reinforcement, the iodine adsorption amount of the aforementioned carbon black (D) is preferably 10 to 200 mg / g. Similarly, from the same viewpoint, the DBP oil absorption amount (dibutyl phthalate oil absorption amount) of the aforementioned carbon black (D) is preferably 10 to 180 ml / 100g. Moreover, by ensuring that both the iodine adsorption amount and the DBP oil absorption amount meet the above ranges, improvements in reinforcement, dispersibility, and durability can be achieved.

[0049] Furthermore, the iodine adsorption capacity of the aforementioned carbon black (D) was determined according to JIS K6217-1 (Method A). Additionally, the DBP oil absorption capacity of the aforementioned carbon black (D) was determined according to JIS K6217-4.

[0050] From the viewpoint of fatigue resistance, the amount of carbon black (D) in the formulation is in the range of 10 to 80 parts by mass relative to 100 parts by mass of diene rubber (A), preferably in the range of 10 to 70 parts by mass, and more preferably in the range of 15 to 50 parts by mass.

[0051] As an indicator of the dispersibility of metal hydroxide (B) and carbon black (D), the dispersibility (ΔG') can be calculated using the following formula (i).

[0052] ΔG'=G'2 / G'1……(i)

[0053] [In formula (i), G'1 represents the storage modulus of the uncured rubber composition at a frequency of 11 Hz, a strain of 42%, and a temperature of 40°C, and G'2 represents the storage modulus of the uncured rubber composition at a frequency of 11 Hz, a strain of 0.28%, and a temperature of 40°C.]

[0054] Furthermore, as described in Japanese Patent Application Publication No. 2006-47070, ΔG' shown in the above formula (i) is an index used to evaluate the agglomeration property of the filler; the smaller ΔG' is, the higher the dispersibility of the filler. Moreover, in this invention, ΔG' is preferably less than 2.3, more preferably 2.1 or less. Furthermore, the lower limit of ΔG' is 0.

[0055] In addition, G'1 and G'2 can be measured, for example, using a rubber processing tester, a vulcanizer, or a dynamic viscoelasticity tester. More specifically, they are measured using the RPA2000 manufactured by Alpha Technologies.

[0056] Furthermore, in this vibration-damping rubber composition, halogenated flame retardants, antimony-based flame retardants, reinforcing agents, silane coupling agents, vulcanizing agents, vulcanization accelerators, vulcanization aids, anti-aging agents, processing oils, etc., may be appropriately added together with the above-mentioned components (A) to (D) as needed. In particular, the addition of silane coupling agents is preferred because the dispersibility is improved through interaction with metal hydroxides.

[0057] As for the aforementioned halogenated flame retardants, those with a melting point below 150°C are preferred, considering their ease of melting during rubber compounding and minimizing the risk of becoming the starting point for rubber damage. By using low-melting-point halogenated flame retardants, the overall Mooney viscosity of the rubber compound is reduced, thus allowing for the uniform dispersion of metal hydroxides and carbon black within the rubber compound. Examples of such low-melting-point halogenated flame retardants include, for example, low-melting-point bromine-based and chlorine-based flame retardants as described above. They can be used alone or in combination of two or more.

[0058] Examples of low-melting-point brominated flame retardants include aliphatic low-melting-point brominated flame retardants such as bis(dibromopropyl)tetrabromobisphenol A (DBP-TBBA), bis(dibromopropyl)tetrabromobisphenol S (DBP-TBBS), tris(dibromopropyl)isocyanurate (TDBPIC), and tris(tribromoneopentyl) phosphate (TTBNPP), as well as aromatic low-melting-point brominated flame retardants such as brominated epoxy resin (TBBA epoxy).

[0059] In addition, examples of low-melting-point chlorine-based flame retardants mentioned above include chlorinated paraffin and chlorinated polyethylene.

[0060] The amount of the halogenated flame retardant is 15 to 60 parts by mass relative to 100 parts by mass of the diene rubber (A). This is because if the amount of the halogenated flame retardant is too small, the desired flame retardancy cannot be obtained; conversely, if the amount is too large, black smoke will be produced during combustion, resulting in poor light transmittance and a decrease in the physical properties of the rubber.

[0061] As an antimony-based flame retardant, antimony trioxide can be cited as an example. From the viewpoint of flame retardancy and rubber properties, an antimony-based flame retardant with a particle size of 0.5 μm or less is preferred.

[0062] The amount of the antimony-based flame retardant is 0.1 to 30 parts by mass relative to 100 parts by mass of the diene rubber (A). That is, if the amount of the antimony-based flame retardant is too small, the desired flame retardancy cannot be obtained; conversely, if the amount is too large, it becomes the starting point for rubber damage, causing a decrease in the physical properties of the rubber.

[0063] Examples of reinforcing agents mentioned above include silica and talc. They can be used alone or in combination of two or more.

[0064] The amount of the reinforcing agent is preferably in the range of 10 to 100 parts by weight relative to 100 parts by weight of the diene rubber (A), and particularly preferably in the range of 20 to 70 parts by weight. That is, if the amount of the reinforcing agent is too small, a certain level of reinforcement cannot be achieved; conversely, if the amount of the reinforcing agent is too large, problems such as a higher dynamic ratio or an increase in viscosity and a deterioration in performance will occur.

[0065] As the aforementioned silane coupling agent, 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 thioether-based silane coupling agent, the vulcanization density is increased, which is particularly effective for low dynamic range and improved durability, and is therefore preferred.

[0066] Examples of mercaptosilane coupling agents include 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane. They can be used alone or in combination of two or more.

[0067] Examples of sulfide-based silane coupling agents include, for instance, 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-dimethylthioamine. These include tetrasulfides such as 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, and 3-trimethoxysilylpropyl methacrylate monosulfide. They can be used alone or in combination of two or more.

[0068] 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. They can be used alone or in combination of two or more.

[0069] Examples of epoxy-based silane coupling agents include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyltriethoxysilane, and 3-epoxypropoxypropylmethyldiethoxysilane. They can be used alone or in combination of two or more.

[0070] Examples of vinyl-based silane coupling agents include vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyldimethylchlorosilane, vinyltrichlorosilane, vinyltriisopropoxysilane, and vinyltri(2-methoxyethoxy)silane. They can be used alone or in combination of two or more.

[0071] From the perspectives of low dynamic ratio and improved durability, the content of the silane coupling agent is preferably 0.1 to 20 parts by mass relative to 100 parts by mass of the diene rubber (A), and more preferably 0.2 to 10 parts by mass.

[0072] Furthermore, from the viewpoint of improving processability during mixing and enhancing rubber properties, it is preferable that the above-mentioned metal hydroxide (B) has been treated with the above-mentioned silane coupling agent.

[0073] Examples of the aforementioned vulcanizing agents include sulfur (powdered sulfur, precipitated sulfur, insoluble sulfur, etc.). They can be used alone or in combination of two or more.

[0074] The amount of the vulcanizing agent is preferably in the range of 0.3 to 7 parts by mass relative to 100 parts by mass of the diene rubber (A), and particularly preferably in the range of 1 to 5 parts by mass. That is, if the amount of the vulcanizing agent is too small, a sufficient cross-linking structure cannot be obtained, and a tendency for the dynamic ratio and aging resistance to deteriorate can be observed. Conversely, if the amount of the vulcanizing agent is too large, a tendency for the heat resistance to decrease can be observed.

[0075] Examples of vulcanization accelerators include thiazole-based, sulfenamide-based, thiuram-based, aldehyde-amine-based, guanidine-based, and thiourea-based vulcanization accelerators. These can be used alone or in combination of two or more. Among these, sulfenamide-based vulcanization accelerators are preferred due to their superior crosslinking reactivity.

[0076] Furthermore, the content of the above-mentioned vulcanization accelerator is preferably in the range of 0.1 to 10 parts by weight relative to 100 parts by weight of the above-mentioned diene rubber (A), and particularly preferably in the range of 0.3 to 5 parts by weight.

[0077] 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.

[0078] 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. They can be used alone or in combination.

[0079] 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 accelerators can be used alone or in combination of two or more.

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

[0081] Furthermore, the content of the above-mentioned vulcanizing aid is preferably in the range of 0.1 to 10 parts by weight relative to 100 parts by weight of the diene rubber (A), 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. They can be used alone or in combination of two or more.

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

[0084] Examples of the aforementioned processing oils include cycloalkane-based oils, paraffinic oils, and aromatic oils. They can be used alone or in combination of two or more.

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

[0086] This vibration-damping rubber composition can be prepared, for example, as follows: The diene rubber (A), metal hydroxide (B), dihydrazide compound (C), carbon black (D), and, as needed, halogenated flame retardants, antimony flame retardants, reinforcing agents, silane coupling agents, vulcanizing accelerators, anti-aging agents, processing oils, etc., are appropriately combined and mixed using a Banbury mixer or similar equipment, starting at a temperature of approximately 50°C and continuing at 100–160°C for approximately 3–5 minutes. Next, vulcanizing agents, vulcanization accelerators, etc., are appropriately added, and the mixture is mixed using open rollers under predetermined conditions (e.g., 60°C × 5 minutes), thereby preparing this vibration-damping rubber composition. Subsequently, the obtained vibration-damping rubber composition is vulcanized at a high temperature (150–170°C) for 5–60 minutes, thereby obtaining a vibration-damping rubber component (vulcanized body) exhibiting flame retardant properties.

[0087] Furthermore, as a material for vibration-damping rubber components, using this vibration-damping rubber composition as described above yields excellent vibration-damping properties such as rubber physical properties and dynamic ratio, as well as excellent flame retardancy. Therefore, this vibration-damping rubber composition prepared as described above is suitable for use in vibration-damping rubber components requiring flame retardancy, such as engine mounts, stabilizer bushings, and suspension bushings used in motor vehicles and trams. In addition to the above applications, it can also be used as a vibration damper for computer hard drives, a vibration damper for general household appliances such as washing machines, and as a vibration damping device and isolation device for buildings and residences. It is a suitable material for use as a vibration-damping rubber component in the building and residential sectors.

[0088] Example

[0089] Next, the embodiments will be described together with comparative examples. However, the present invention is not limited to these embodiments.

[0090] First, before the embodiments and comparative examples, prepare the materials shown below.

[0091] [NR]

[0092] natural rubber

[0093] [IR]

[0094] Nipol IR2200 (manufactured by ZEON Corporation, Japan)

[0095] [BR]

[0096] Nipol 1220 (manufactured by ZEON Corporation, Japan)

[0097] [Diacylhydrazide compound (i)]

[0098] IDH (manufactured by Otsuka Chemical Co., Ltd.)

[0099] [Diacylhydrazide compound (ii)]

[0100] Adipic acid dihydrazide (ADH, manufactured by Otsuka Chemical Co., Ltd.)

[0101] [Aluminum hydroxide]

[0102] KH-101 (manufactured by KC Corporation, average particle size 1.10 μm)

[0103] [Magnesium hydroxide]

[0104] KISUMA5 (manufactured by Kyowa Chemical Co., Ltd., with an average particle size of 0.9 μm)

[0105] [Carbon black]

[0106] SHO BLACK IP200 (manufactured by Tokai Carbon Co., Ltd., iodine adsorption capacity 14-28 mg / g, DBP specific surface area 118-132 m²) 2 / g)

[0107] Zinc oxide

[0108] Two types of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd.)

[0109] [Silane coupling agent]

[0110] NXT Z45 (manufactured by MOMENTIVE)

[0111] [Stearic acid]

[0112] Sakura (beaded stearic acid, manufactured by Nippon Oil Company)

[0113] [Amine-based anti-aging agents]

[0114] OZONONE 6C (manufactured by Seiko Chemical Co., Ltd.)

[0115] [wax]

[0116] Microcrystalline wax (SUNNOC, manufactured by Ouchi Shinsei Chemical Co., Ltd.)

[0117] [Halogen-based flame retardants]

[0118] Brominated flame retardant (FCP680G, manufactured by Lingyu Chemical Co., Ltd., melting point 105-115℃)

[0119] [Cycloalkane oil]

[0120] SUNTHENE 410 (manufactured by Sun Oil Corporation of Japan)

[0121] [Vulcanization accelerator]

[0122] sulfenamide-based vulcanization accelerator (NOCCELER CZ-G, manufactured by Ouchi Shinsei Chemical Co., Ltd.)

[0123] [sulfur]

[0124] Sulfur (manufactured by Karuizawa Refinery Co., Ltd.)

[0125] [Example 1]

[0126] A vibration-damping rubber composition was prepared by mixing 100 parts by weight of NR, 1 part by weight of dihydrazide compound (i), 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 1.5 parts by weight of amine anti-aging agent, 2 parts by weight of wax, 40 parts by weight of aluminum hydroxide, 40 parts by weight of carbon black, and 5 parts by weight of cycloalkane oil at 140°C for 5 minutes using a Banbury mixer. Next, 2.3 parts by weight of sulfur and 1.2 parts by weight of vulcanization accelerator were added, and the mixture was mixed at 60°C for 5 minutes using open rollers.

[0127] [Examples 2-13, Comparative Examples 1-8]

[0128] The anti-vibration rubber composition was prepared according to Example 1, except that the proportions of each component were varied as shown in Tables 1 and 2 below.

[0129] 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.

[0130] <<ΔG'>>

[0131] For each vibration-damping rubber composition, the storage modulus of the uncured rubber composition at a frequency of 11 Hz and 40°C (storage modulus G'1 at 42% strain and storage modulus G'2 at 0.28% strain) was measured using an RPA2000 (manufactured by Alpha Technologies). Then, based on the above measurement results, ΔG' as shown in the following formula (i) was calculated.

[0132] Then, cases where ΔG' is below 2.1 are rated as "〇 (very good)", cases where it is greater than 2.1 and less than 2.3 are rated as "△ (good)", and cases where it is above 2.3 are rated as "× (poor)".

[0133] ΔG'=G'2 / G'1……(i)

[0134] Dumbbell Tensile Test (TB, EB)

[0135] Each vibration-damping rubber composition was stamped (vulcanized) at 150°C for 20 minutes to produce a rubber sheet with a thickness of 2 mm. Then, a JIS No. 5 dumbbell was punched out from the rubber sheet, and the dumbbell was used to conduct a dumbbell tensile test (determination of TB and EB) according to JIS K6251.

[0136] Then, in TB (tear strength), cases with a value of 19 MPa or above are rated as "〇 (very good)", cases with a value of 17 MPa or above but less than 19 MPa are rated as "△ (good)", and cases with a value less than 17 MPa are rated as "× (poor)".

[0137] In addition, in EB (elongation at break), a value of 500% or more is rated as "0 (very good)", a value of 400% or more but less than 500% is rated as "△ (good)" and a value of less than 400% is rated as "× (poor)".

[0138] Light transmittance

[0139] Each vibration-damping rubber composition was stamped (vulcanized) at 150°C for 60 minutes to produce rubber blocks with a square diameter of 76.2 mm and a thickness of 25.4 mm. Then, to evaluate the flame retardancy of the rubber blocks, a light transmittance test of the smoke produced when the rubber sheet was burning was conducted according to ASTM E662.

[0140] Then, in the non-flaming or flaming test, the Ds value (specific optical density) of the smoke 4 minutes after the start of heating is less than 200 is evaluated as "〇 (very good)", the value is 200 or more but less than 300 as "△ (good)" and the value is 300 or more as "× (poor)".

[0141] Oxygen Index

[0142] Each vibration-damping rubber composition was press-formed (vulcanized) at 150°C for 20 minutes to produce a rubber sheet with a thickness of 2 mm. Then, in order to evaluate the flammability of the rubber sheet, the minimum oxygen concentration (capacity%) required for sustained combustion of the rubber sheet, i.e., the oxygen index, was determined according to JIS K7201.

[0143] Then, the cases with an oxygen index of 22% or higher are rated as "◎ (excellent)", the cases with an oxygen index of 20% or higher but less than 22% are rated as "〇 (very good)", the cases with an oxygen index of 19% or higher but less than 20% are rated as "△ (good)" and the cases with an oxygen index of less than 19% are rated as "× (poor)".

[0144] "Anti-vibration performance"

[0145] Each vibration-damping rubber composition was stamped (vulcanized) at 150℃ for 30 minutes to produce cylindrical test pieces (50mm in diameter and 25mm in height). Circular metal parts (60mm in diameter and 6mm in thickness) were mounted on the upper and lower surfaces of each piece. The dynamic spring constant (Kd100) and static spring constant (Ks) were measured according to JIS K6394. Based on these values, the dynamic ratio (Kd100 / Ks) was calculated.

[0146] Then, as an evaluation of vibration damping performance, cases with a dynamic magnification ratio of less than 1.6 are rated as "0 (very good)", cases with a dynamic magnification ratio of more than 1.6 but less than 2 are rated as "△ (good)", and cases with a dynamic magnification ratio of more than 2 are rated as "× (poor)".

[0147] Table 1

[0148] (parts by weight)

[0149]

[0150] Table 2

[0151] (parts by weight)

[0152]

[0153] As can be seen from the results in Table 1 above, the rubber composition of the embodiment achieved excellent results in flame retardancy evaluation (light transmittance, oxygen index), as well as excellent vibration damping performance (vibration damping rubber properties) and tensile properties (rubber properties in dumbbell tensile test (TB, EB)).

[0154] In contrast, as shown in Table 2 above, the rubber composition of the comparative example differs from the rubber composition of the examples, and shows a "× (poor)" rating in more than one evaluation item.

[0155] Specifically, the rubber composition of Comparative Example 1 did not contain a dihydrazide compound, resulting in poor dispersibility of aluminum hydroxide and a ΔG' value that did not show the expected value, leading to poor vibration damping and tensile properties. In Comparative Example 2, the amount of dihydrazide compound added was higher than specified in this invention. Although the flame retardant evaluation was excellent, the rubber was harder, resulting in poor tensile properties and vibration damping. In Comparative Example 3, the amount of carbon black added was lower than specified in this invention. Although the flame retardant evaluation was excellent, the rubber had lower reinforcement, poor tensile properties, and poor vibration damping. In Comparative Example 4, the amount of carbon black added was higher than specified in this invention. Although the flame retardant evaluation was excellent, the rubber hardness increased, resulting in poor tensile properties and vibration damping. In Comparative Example 5, the amount of aluminum hydroxide added was lower than specified in this invention. Although the vibration damping performance was excellent, the flame retardant evaluation was poor. In Comparative Example 6, the amount of aluminum hydroxide added was higher than specified in this invention. Although the flame retardant evaluation was excellent, the ΔG' value did not show the expected value, resulting in poor tensile properties and vibration damping. In Comparative Example 7, although the vibration damping performance was excellent, the flame retardant evaluation was poor because it did not contain metal hydroxides. In Comparative Example 8, the dispersion of aluminum hydroxide was poor and the rubber reinforcement was low because it did not contain carbon black, resulting in poor vibration damping performance and tensile properties.

[0156] Furthermore, while the above embodiments illustrate specific aspects of the invention, these embodiments are merely examples and not intended to be limiting. It is intended that various modifications as understood by those skilled in the art be included within the scope of this invention.

[0157] Industrial applicability

[0158] This vibration-damping rubber composition is preferably used as a material for engine mounts, stabilizer bushings, suspension bushings, etc., used in motor vehicles, trams, etc. In addition, it can also be used as a material for vibration damping dampers for computer hard drives, vibration damping dampers for general household appliances such as washing machines, vibration damping walls for buildings and vibration damping devices such as vibration damping (damping) dampers in the construction and residential fields, and as a component (vibration-damping rubber component) of vibration isolation devices.

Claims

1. A flame-retardant and vibration-damping rubber composition comprising the following (A) to (D), wherein, Compared to 100 parts by weight of (A) below, the proportion of (B) below is 20 to 40 parts by weight, the proportion of (C) below is 0.01 to 5.0 parts by weight, and the proportion of (D) below is 10 to 80 parts by weight. (A) Diene-based rubber, (B) Metal hydroxides, (C) Diacylhydrazide compounds, (D) Carbon black, The dispersion ΔG' of the flame-retardant vibration-damping rubber composition, as shown by the following formula (i), is less than 2.

3. ΔG'=G'2 / G'1……(i) In equation (i), G'1 represents the storage modulus of the uncured rubber composition at a frequency of 11 Hz, a strain of 42%, and a temperature of 40 °C, and G'2 represents the storage modulus of the uncured rubber composition at a frequency of 11 Hz, a strain of 0.28%, and a temperature of 40 °C.

2. The flame-retardant and vibration-damping rubber composition according to claim 1, wherein, The metal hydroxide (B) is selected from at least one of aluminum hydroxide and magnesium hydroxide.

3. The flame-retardant and vibration-damping rubber composition according to claim 1 or 2, wherein, The dihydrazide compound (C) is at least one of autodihydrazide and isophthalic dihydrazide.

4. The flame-retardant and vibration-damping rubber composition according to claim 1 or 2, wherein, The carbon black (D) has a DBP oil absorption capacity of 10~180ml / 100g and an iodine adsorption capacity of 10~200mg / g.

5. A flame-retardant vibration-damping rubber component, wherein, The flame-retardant vibration-damping rubber component is formed from the vulcanized form of the flame-retardant vibration-damping rubber composition according to any one of claims 1 to 4.

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