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

Abstract

This flame-retardant vibration-damping rubber composition comprises the following (A) to (D), the proportion of (B) being 20-150 parts by mass, the proportion of (C) being 0.01-5.0 parts by mass, and the proportion of (D) being 10-80 parts by mass with respect to 100 parts by mass of (A). This makes it possible to provide a flame-retardant vibration-damping rubber composition and a flame-retardant vibration-damping rubber member that are excellent in vibration-damping rubber properties such as rubber physical characteristics and dynamic magnification while maintaining flame-retardant property. (A) Diene rubber. (B) Metal hydroxide. (C) Dihydrazide compound. (D) Carbon black.

Description

Technical Field

[0001] The present invention relates to a flame-retardant vibration-damping rubber composition and a flame-retardant vibration-damping rubber member used for vibration-damping applications in vehicles such as automobiles and trains.

Background Art

[0002] Generally, vibration-damping rubber members are used in automobiles and railway vehicles for the purpose of reducing vibration and noise. For the above vibration-damping rubber members, in order to enhance quietness, it is required to reduce the dynamic magnification ratio (by reducing the value of the dynamic magnification ratio [dynamic spring constant (Kd) / static spring constant (Ks)]). In addition, for the above vibration-damping rubber members, in addition to vibration-damping rubber properties such as a low dynamic magnification ratio, for example, flame retardancy may be required. Regarding the flame retardancy of rubber, there is a method of adding a flame retardant such as a halogen-based flame retardant, a phosphorus-based flame retardant, or a metal hydroxide (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when attempting to develop flame retardancy by adding the above-mentioned flame retardants, a phenomenon may occur in which the rubber physical properties and the dynamic magnification ratio deteriorate. For example, when using aluminum hydroxide as a flame retardant, it is necessary to add a large amount of aluminum hydroxide to sufficiently develop its flame retardancy, which leads to the deterioration of the rubber physical properties and the dynamic magnification ratio. In Patent Document 2, the applicant has already developed a technique in which a halogen-based flame retardant with a low melting point and aluminum hydroxide with a small particle size are contained in a specific amount in combination with a diene rubber, which is a polymer of a vibration-damping rubber composition, in order to improve the physical properties of the rubber and the dynamic magnification while maintaining the flame retardant effect. However, there is still room for improvement even with this technique.

[0005] The present invention has been made in view of such circumstances, and provides a flame-retardant vibration-damping rubber composition and a flame-retardant vibration-damping rubber member that maintain flame retardancy and are excellent in vibration-damping rubber properties such as rubber physical properties and dynamic magnification.

Means for Solving the Problems

[0006] The gist of the present invention is as follows [1] to [5]. [1] A flame-retardant vibration-damping rubber composition containing the following (A) to (D), wherein the ratio of the following (B) is 20 to 150 parts by mass, the ratio of the following (C) is 0.01 to 5.0 parts by mass, and the ratio of the following (D) is 10 to 80 parts by mass with respect to 100 parts by mass of the following (A). Flame-retardant vibration-damping rubber composition. (A) Diene rubber. (B) Metal hydroxide. (C) Dihydrazide compound. (D) Carbon black. [2] The flame-retardant vibration-damping rubber composition according to [1], wherein the metal hydroxide (B) is at least one selected from aluminum hydroxide and magnesium hydroxide. [3] The flame-retardant vibration-damping rubber composition according to [1] or [2], wherein the dihydrazide compound (C) is at least one selected from adipic acid dihydrazide and isophthalic acid dihydrazide. [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 amount of 10 to 200 mg / g. [5] A flame-retardant vibration-damping rubber member comprising a vulcanizate of the flame-retardant vibration-damping rubber composition according to any one of [1] to [4].

[0007] That is, in conventional flame-retardant vibration-damping rubber, in order to obtain flame retardancy, it is necessary to add a large amount of metal hydroxide. As a result, poor dispersion of the metal hydroxide occurs, and the rubber physical properties and vibration-damping rubber properties such as dynamic magnification factor deteriorate. Therefore, the present inventors have conducted intensive studies to solve the above problems. Even when a metal hydroxide is used for a diene rubber which is a polymer of vibration-damping rubber, a method for improving the rubber physical properties and improving the vibration-damping rubber properties such as dynamic magnification factor (reducing the dynamic magnification factor) has been studied. As a result of conducting various experiments, it has been found that the combined use of a dihydrazide compound and carbon black is effective in improving the dispersibility of the metal hydroxide. By containing these respective materials in a specific ratio, it has been possible to improve the vibration-damping rubber properties while maintaining the flame retardancy. The reason why such a thing has become possible is presumed as follows. That is, the dihydrazide compound exhibits an action of increasing the crosslink density of the rubber and increasing the rubber viscosity. By this, shear is applied during the kneading of the rubber, and the dispersibility of the metal hydroxide in the rubber can be improved. Further, the above-mentioned dispersibility is further promoted by the interaction between the dihydrazide having a polar group and the hydroxyl group of the metal hydroxide. In addition, carbon black has a large specific surface area, a complex fine structure, and a chemically active surface (functional groups such as hydroxyl groups and carboxyl groups are present), and is rich in reactivity with rubber molecular chains, so it has high reinforcing properties. Therefore, by adding carbon black, shear is applied during the kneading of the rubber, and the dispersibility of the metal hydroxide in the rubber can be further improved. Then, by combining a metal hydroxide, a dihydrazide compound, and carbon black in specific ratios with respect to the diene rubber that is the polymer of the vibration isolator rubber, it is possible to aim for improved dispersibility due to the interaction between the dihydrazide compound and the metal hydroxide and improved dispersibility of the metal hydroxide based on the increased shear during kneading by the dihydrazide compound and the carbon black, and thus it becomes possible to obtain desired vibration isolator rubber properties. Note that only one of the dihydrazide compound and the carbon black cannot sufficiently obtain the above-described effects. Also, even when a monohydrazide compound is used instead of the dihydrazide compound, it is possible to improve the dispersibility of the metal hydroxide and the carbon black, but the dihydrazide compound is more reactive, and the dispersibility of the metal hydroxide and the carbon black is improved, and the vibration isolator rubber properties are promoted.

Advantages of the Invention

[0008] From the above, the flame-retardant vibration isolator rubber composition of the present invention is excellent in flame retardancy and exhibits excellent effects in terms of vibration isolator rubber properties such as rubber physical properties and dynamic magnification ratio. And the flame-retardant vibration isolator rubber composition of the present invention can be suitably used as a material for vibration isolator rubber members that require flame retardancy, for example, engine mounts, stabilizer bushes, suspension bushes, etc. used in vehicles such as automobiles and trains, and vibration isolator rubber members in the construction and housing fields.

Embodiments for Carrying Out the Invention

[0009] Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to this embodiment.

[0010] The flame-retardant vibration isolator rubber composition (hereinafter referred to as "this vibration isolator rubber composition"), which is one embodiment of the present invention, contains the following (A) to (D) in specific ratios as described above. (A) Diene rubber. (B) Metal hydroxide. (C) Dihydrazide compound. (D) Carbon black.

[0011] [Diene rubber (A)] Examples of the diene rubber (A) used in the present anti-vibration rubber composition include 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), chloroprene rubber (CR), etc. These can be used alone or in combination of two or more. Among these, natural rubber is preferably used in terms of strength and reduction of dynamic magnification ratio.

[0012] [Metal hydroxide (B)] As the metal hydroxide (B), aluminum hydroxide and magnesium hydroxide are preferably used. These metal hydroxides (B) can be used alone or in combination of two or more. And, from the viewpoint of rubber physical properties in particular, those having an average particle size of 2 μm or less are preferred, more preferably those having an average particle size of 1.5 μm or less, and particularly preferably those having an average particle size of 1.1 μm or less. That is, by uniformly dispersing such a metal hydroxide with a small particle size and a large surface area, more excellent rubber physical properties can be obtained. The average particle size of the above metal hydroxide (B) is the volume average particle size, and can be derived, for example, by using a sample arbitrarily extracted from the population and measuring it using a laser diffraction scattering type particle size distribution measuring device.

[0013] The compounding amount of the above metal hydroxide (B) is 20 to 150 parts by mass, preferably 20 to 80 parts by mass, based on 100 parts by mass of the diene rubber (A). That is, if the compounding amount of the above metal hydroxide (B) is too small, the desired flame retardancy cannot be obtained, and conversely, if the compounding amount of the above metal hydroxide (B) is too large, it will cause deterioration of rubber physical properties.

[0014] [Dihydrazide compound (C)] The above dihydrazide compound (C) is used to improve the dispersibility of the metal hydroxide (B) and carbon black (D). And as the above dihydrazide compound (C), preferably, a dihydrazide compound represented by the following general formula (1) is used.

[0015]

Chemical formula

[0016] In the above general formula (1), R is preferably an alkylene group having 4 to 12 carbon atoms or a phenylene group.

[0017] And as specific examples of the above dihydrazide compound (C), for example, adipic acid dihydrazide, isophthalic acid dihydrazide, phthalic acid dihydrazide, terephthalic acid dihydrazide, succinic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, oxalic acid dihydrazide, dodecanoic acid dihydrazide, etc. can be mentioned. These can be used alone or in combination of two or more. Among them, from the viewpoint of high dispersibility of the metal hydroxide (B) and carbon black (D), adipic acid dihydrazide and isophthalic acid dihydrazide are preferred.

[0018] The content of the above dihydrazide compound (C) is 0.01 to 5.0 parts by mass, preferably 0.1 to 5.0 parts by mass, more preferably 0.3 to 3.0 parts by mass, based on 100 parts by mass of the diene rubber (A), from the viewpoint of high dispersibility of the metal hydroxide (B) and carbon black (D).

[0019] [Carbon black (D)] As the above carbon black (D), for example, various grades of carbon black such as SAF grade, ISAF grade, HAF grade, MAF grade, FEF grade, GPF grade, SRF grade, FT grade, MT grade, etc. are used. These can be used alone or in combination of two or more. Among them, from the viewpoint of vibration characteristics and fatigue resistance, FEF grade carbon black is preferably used.

[0020] From the viewpoints of durability, reduction of dynamic magnification ratio, and reinforcement, it is preferable that the iodine adsorption amount of the carbon black (D) is 10 to 200 mg / g. From the same viewpoints, it is preferable that the DBP oil absorption amount (dibutyl phthalate oil absorption amount) of the carbon black (D) is 10 to 180 ml / 100 g. By satisfying both the iodine adsorption amount and the DBP oil absorption amount within the above ranges, improvement in reinforcement, dispersibility, and durability can be achieved. Note that the iodine adsorption amount of the carbon black (D) is a value measured in accordance with JIS K6217-1 (Method A). Also, the DBP oil absorption amount of the carbon black (D) is a value measured in accordance with JIS K6217-4.

[0021] From the viewpoint of fatigue resistance, the compounding amount of the above carbon black (D) is in the range of 10 to 80 parts by mass, preferably in the range of 10 to 70 parts by mass, more preferably in the range of 15 to 50 parts by mass, based on 100 parts by mass of the diene rubber (A).

[0022] As an index of the dispersibility of the metal hydroxide (B) and the carbon black (D), the dispersity (ΔG') calculated by the following formula (i) may be used. ΔG' = G'2 / G'1 ……(i) [In formula (i), G'1 is the storage modulus of the unvulcanized rubber composition at a frequency of 11 Hz, a strain of 42%, and 40°C, and G'2 is the storage modulus of the unvulcanized rubber composition at a frequency of 11 Hz, a strain of 0.28%, and 40°C.]

[0023] Note that ΔG' represented by the above formula (i) is an index for evaluating the aggregability of the filler, and is based on the description in JP-A-2006-47070. The smaller ΔG' is, the higher the dispersity of the filler is. In the present invention, it is preferable that ΔG' is less than 2.3, more preferably 2.1 or less. Note that the lower limit of ΔG' is 0. In addition, G'1 and G'2 can be measured, for example, by a rubber processing tester, a curastometer, dynamic viscoelasticity measurement, etc. More specifically, it is measured by the RPA2000 manufactured by Alpha Technology Co., Ltd.

[0024] In this anti-vibration rubber composition, in addition to the above components (A) to (D), a halogen-based flame retardant, an antimony-based flame retardant, a reinforcing agent, a silane coupling agent, a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, an antioxidant, a process oil, etc. can be appropriately blended as needed. In particular, when a silane coupling agent is blended, it is preferable because the dispersibility is improved by the interaction with the metal hydroxide.

[0025] As the above halogen-based flame retardant, a halogen-based flame retardant having a melting point of 150°C or lower is preferable because it is easily melted during kneading of the rubber composition and has little risk of becoming a starting point of rubber fracture. By using a low melting point halogen-based flame retardant, the Mooney viscosity of the entire rubber composition decreases, so that the metal hydroxide and carbon black can be uniformly dispersed in the rubber composition. Examples of such low melting point halogen-based flame retardants include the above-mentioned low melting point bromine-based flame retardants and chlorine-based flame retardants. These may be used alone or in combination of two or more.

[0026] Examples of the above low melting point bromine-based flame retardants include aliphatic ones such as bis(dibromopropyl)tetrabromobisphenol A (DBP-TBBA), bis(dibromopropyl)tetrabromobisphenol S (DBP-TBBS), tris(dibromopropyl)isocyanurate (TDBPIC), tris(tribromoneopentyl)phosphate (TTBNPP), etc., and aromatic ones such as brominated epoxy resin (TBBA epoxy).

[0027] Examples of the above low melting point chlorine-based flame retardants include chlorinated paraffin, chlorinated polyethylene, etc.

[0028] The compounding amount of the above halogen-based flame retardant is 15 to 60 parts by mass with respect to 100 parts by mass of the above diene-based rubber (A). That is, if the compounding amount of the above halogen-based flame retardant is too small, the desired flame retardancy cannot be obtained. Conversely, if the compounding amount is too large, black smoke is generated by combustion, resulting in deterioration of light transmittance and also causing a decrease in rubber physical properties.

[0029] Examples of the above antimony-based flame retardant include antimony trioxide, etc. From the viewpoints of flame retardancy and rubber physical properties, those with a particle size of 0.5 μm or less are preferred.

[0030] The compounding amount of the above antimony-based flame retardant is 0.1 to 30 parts by mass with respect to 100 parts by mass of the above diene-based rubber (A). That is, if the compounding amount of the above antimony-based flame retardant is too small, the desired flame retardancy cannot be obtained. Conversely, if the compounding amount is too large, it becomes a starting point for rubber fracture and causes a decrease in rubber physical properties.

[0031] Examples of the above reinforcing agent include silica, talc, etc. These can be used alone or in combination of two or more.

[0032] The compounding amount of the above reinforcing agent is preferably in the range of 10 to 100 parts by mass, particularly preferably in the range of 20 to 70 parts by mass, with respect to 100 parts by mass of the above diene-based rubber (A). That is, if the compounding amount is too small, a certain level of reinforcing property cannot be satisfied. Conversely, if the compounding amount is too large, problems such as an increase in dynamic magnification or an increase in viscosity and deterioration occur.

[0033] Examples of the above silane coupling agent include 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., which can be used alone or in combination of two or more. Among them, when the above silane coupling agent is a mercapto-based silane coupling agent or a sulfide-based silane coupling agent, it is preferable because the vulcanization density increases and it is particularly effective in reducing the dynamic magnification and improving durability.

[0034] Examples of the mercapto-based silane coupling agent include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, etc. These can be used alone or in combination of two or more.

[0035] Examples of the sulfide-based silane coupling agent 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, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl 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.

[0036] Examples of the amine-based silane coupling agent include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-(N-phenyl)aminopropyltrimethoxysilane, etc. These can be used alone or in combination of two or more.

[0037] Examples of the epoxy-based silane coupling agent include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, etc. These can be used alone or in combination of two or more.

[0038] Examples of the vinyl-based silane coupling agent include vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(β-methoxyethoxy)silane, vinyldimethylchlorosilane, vinyltrichlorosilane, vinyltriisopropoxysilane, vinyltris(2-methoxyethoxy)silane, etc. These can be used alone or in combination of two or more.

[0039] Since the content of these silane coupling agents is excellent in reducing the dynamic magnification ratio, improving durability, etc., it is preferably 0.1 to 20 parts by mass, more preferably 0.2 to 10 parts by mass, based on 100 parts by mass of the diene rubber (A).

[0040] It is preferable that the metal hydroxide (B) is treated with the above silane coupling agent from the viewpoints of improving the processability during kneading and improving the rubber physical properties.

[0041] Examples of the vulcanizing agent include sulfur (powder sulfur, precipitated sulfur, insoluble sulfur), etc. These can be used alone or in combination of two or more.

[0042] The compounding amount of the vulcanizing agent is preferably in the range of 0.3 to 7 parts by mass, particularly preferably in the range of 1 to 5 parts by mass, based on 100 parts by mass of the diene rubber (A). That is, if the compounding amount of the vulcanizing agent is too small, a sufficient crosslinked structure cannot be obtained, and the dynamic magnification ratio and the resistance to sagging tend to deteriorate. On the contrary, if the compounding amount of the vulcanizing agent is too large, the heat resistance tends to decrease.

[0043] Examples of the vulcanization accelerator include vulcanization accelerators such as thiazole-based, sulfenamide-based, thiuram-based, aldehyde ammonia-based, aldehyde amine-based, guanidine-based, and thiourea-based ones. These can be used alone or in combination of two or more. Among these, sulfenamide-based vulcanization accelerators are preferred in terms of excellent crosslinking reactivity.

[0044] In addition, the content of the vulcanization accelerator is preferably in the range of 0.1 to 10 parts by mass, particularly preferably in the range of 0.3 to 5 parts by mass, based on 100 parts by mass of the diene rubber (A).

[0045] Examples of the thiazole-based vulcanization accelerator include dibenzothiazyl disulfide (MBTS), 2-mercaptobenzothiazole (MBT), sodium 2-mercaptobenzothiazole (NaMBT), zinc 2-mercaptobenzothiazole (ZnMBT), etc. These can be used alone or in combination of two or more.

[0046] Examples of the sulfenamide-based vulcanization accelerator include N-oxydiethylene-2-benzothiazolyl sulfenamide (NOBS), N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), N-t-butyl-2-benzothiazoyl sulfenamide (BBS), N,N'-dicyclohexyl-2-benzothiazoyl sulfenamide, etc. These can be used alone or in combination of two.

[0047] Examples of the thiuram-based vulcanization accelerator include tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), tetrabutylthiuram disulfide (TBTD), tetrakis(2-ethylhexyl)thiuram disulfide (TOT), tetrabenzylthiuram disulfide (TBzTD), etc. These can be used alone or in combination of two or more.

[0048] Examples of the vulcanization accelerator include zinc oxide (ZnO), stearic acid, magnesium oxide, etc. These can be used alone or in combination of two or more.

[0049] Also, the content of the vulcanization accelerator is preferably in the range of 0.1 to 10 parts by mass, particularly preferably in the range of 0.3 to 7 parts by mass, based on 100 parts by mass of the diene rubber (A).

[0050] Examples of the anti-aging agent include carbamate-based anti-aging agents, phenylenediamine-based anti-aging agents, phenol-based anti-aging agents, diphenylamine-based anti-aging agents, quinoline-based anti-aging agents, imidazole-based anti-aging agents, waxes, etc. These can be used alone or in combination of two or more.

[0051] Also, the content of the anti-aging agent is preferably in the range of 0.5 to 15 parts by mass, particularly preferably in the range of 1 to 10 parts by mass, based on 100 parts by mass of the diene rubber (A).

[0052] Examples of the process oil include naphthenic oil, paraffinic oil, aromatic oil, etc. These can be used alone or in combination of two or more.

[0053] Also, the content of the process oil is preferably in the range of 1 to 35 parts by mass, particularly preferably in the range of 3 to 30 parts by mass, based on 100 parts by mass of the diene rubber (A).

[0054] This anti-vibration rubber composition can be prepared, for example, as follows. That is, the above diene rubber (A), metal hydroxide (B), dihydrazide compound (C), carbon black (D), and, if necessary, halogen-based flame retardants, antimony-based flame retardants, reinforcing agents, silane coupling agents, vulcanization aids, anti-aging agents, process oils, etc. are appropriately blended, and these are kneaded starting from a temperature of about 50 °C using a Banbury mixer or the like, and kneaded at 100 - 160 °C for about 3 - 5 minutes. Next, a vulcanizing agent, a vulcanization accelerator, etc. are appropriately blended thereto, and kneaded under predetermined conditions (for example, 60 °C × 5 minutes) using an open roll, whereby this anti-vibration rubber composition can be prepared. Thereafter, the obtained anti-vibration rubber composition is vulcanized at a high temperature (150 - 170 °C) for 5 - 60 minutes to obtain an anti-vibration rubber member (vulcanizate) exhibiting flame retardancy.

[0055] And, by using the above anti-vibration rubber composition as the material of the anti-vibration rubber member, it is possible to obtain excellent anti-vibration rubber characteristics such as rubber physical properties and dynamic magnification ratio, and also to obtain an excellent flame retardancy effect. From this, the anti-vibration rubber composition prepared as above is suitably used for anti-vibration rubber members for which flame retardancy is required, for example, engine mounts, stabilizer bushes, suspension bushes, etc. used in vehicles such as automobiles and trains. In addition to the above applications, it can also be used for vibration damping dampers of computer hard disks, vibration damping dampers of general household appliances such as washing machines, and applications of seismic isolation (vibration damping) devices and seismic isolation devices such as building seismic walls and seismic isolation (vibration damping) dampers in the construction and housing fields. It can be suitably used as the material of the anti-vibration rubber member in the construction and housing fields.

Examples

[0056] Next, the examples will be described together with the comparative examples. However, the present invention is not limited to these examples.

[0057] First, prior to the examples and comparative examples, the materials shown below were prepared.

[0058] [NR] Natural rubber

[0059] [IR] Nipol IR2200 (manufactured by Zeon Corporation, Japan)

[0060] [BR] Nipol 1220 (manufactured by Zeon Corporation, Japan)

[0061] [Dihydrazide compound (i)] Isophthalic acid dihydrazide (IDH, manufactured by Otsuka Chemical Co., Ltd.)

[0062] [Dihydrazide compound (ii)] Adipic acid dihydrazide (ADH, manufactured by Otsuka Chemical Co., Ltd.)

[0063] [Aluminum hydroxide] KH-101 (manufactured by KC, average particle size 1.10 μm)

[0064] [Magnesium hydroxide] Kisuma 5 (manufactured by Kyowa Chemical Industry Co., Ltd., average particle size 0.9 μm)

[0065] [Carbon black] Shoublack IP200 (manufactured by Tokai Carbon Co., Ltd., iodine adsorption amount 14 - 28 mg / g, DBP specific surface area 118 - 132 m 2 / g)

[0066] [Zinc oxide] Two types of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd.)

[0067] [Silane coupling agent] NXT Z45 (manufactured by Momentive)

[0068] [Stearic acid] Bead stearic acid sakura (manufactured by NOF Corporation)

[0069] [Amine-based antioxidant] Ozonone 6C (manufactured by Seiko Chemical Co., Ltd.)

[0070] [Wax] Microcrystalline wax (manufactured by Sannock, Ouchi Shinsei Chemical Co., Ltd.)

[0071] [Halogen-based flame retardant] Bromine-based flame retardant (FCP680G, manufactured by Suzaki Chemical Co., Ltd., melting point 105 - 115°C)

[0072] [Naphthene oil] Sansen 410 (manufactured by Nippon Sanso Corporation)

[0073] [Vulcanization accelerator] Sulfenamide-based vulcanization accelerator (Nocceler CZ-G, manufactured by Ouchi Shinsei Chemical Co., Ltd.)

[0074] [Sulfur] Sulfur (manufactured by Karuizawa Refinery)

[0075] [Example 1] 100 parts by mass of NR, 1 part by mass of dihydrazide compound (i), 5 parts by mass of zinc oxide, 2 parts of stearic acid, 1.5 parts by mass of amine-based antioxidant, 2 parts by mass of wax, 40 parts by mass of aluminum hydroxide, 40 parts by mass of carbon black, and 5 parts by mass of naphthene oil were blended, and these were kneaded at 140°C for 5 minutes using a Banbury mixer. Next, 2.3 parts by mass of sulfur and 1.2 parts by mass of vulcanization accelerator were blended thereto, and kneaded at 60°C for 5 minutes using an open roll to prepare a vibration damping rubber composition.

[0076] [Examples 2 - 13, Comparative Examples 1 - 8] As shown in Tables 1 and 2 below, vibration damping rubber compositions were prepared according to Example 1 except that the blending amounts and the like of each component were changed.

[0077] Using the vibration damping rubber compositions of the examples and comparative examples thus obtained, evaluations of each property were conducted according to the following criteria. The results are shown together with Tables 1 and 2 below.

[0078] [[DELTA]G'] For each vibration isolation rubber composition, using an RPA2000 (manufactured by Alpha Technology), the storage elastic modulus of the unvulcanized rubber composition (storage elastic modulus G'1 at a strain of 42% and storage elastic modulus G'2 at a strain of 0.28%) was measured at a frequency of 11 Hz and 40°C. Then, based on the above measurement results, ΔG' represented by the following formula (i) was calculated. And those with ΔG' of 2.1 or less were evaluated as "〇 (very good)", those greater than 2.1 and less than 2.3 were evaluated as "△ (good)", and those 2.3 or more were evaluated as "× (poor)". ΔG' = G'2 / G'1 ……(i)

[0079] ≪Dumbbell Tensile Test (TB, EB)≫ Each vibration isolation rubber composition was press-molded (vulcanized) under the conditions of 150°C × 20 minutes to produce a rubber sheet with a thickness of 2 mm. Then, a JIS No. 5 dumbbell was punched out from this rubber sheet, and using this dumbbell, a dumbbell tensile test (measurement of TB and EB) was conducted according to JIS K6251. And for TB (breaking strength), those with a value of 19 MPa or more were evaluated as "〇 (very good)", those with a value of 17 MPa or more and less than 19 MPa were evaluated as "△ (good)", and those less than 17 MPa were evaluated as "× (poor)". Also, for EB (elongation at break), those with a value of 500% or more were rated as "○ (very good)", those with a value of 400% or more and less than 500% were rated as "△ (good)", and those less than 400% were rated as "× (poor)".

[0080] ≪Light Transmittance≫ Each vibration isolation rubber composition was press-molded (vulcanized) under the conditions of 150°C × 60 minutes to produce a rubber block with a size of 76.2 mm square and a thickness of 25.4 mm. Then, in order to evaluate the flame retardancy of the rubber block, in accordance with ASTM E662, a light transmittance test of the smoke generated during the combustion of this rubber sheet was conducted. Then, those with a Ds value (specific optical density) of the smoke after 4 minutes from the start of heating in the non-Fleming or Fleming test less than 200 were evaluated as "〇 (very good)", those with a value of 200 or more and less than 300 as "△ (good)", and those with a value of 300 or more as "× (poor)".

[0081] ≪Oxygen Index≫ Each anti-vibration rubber composition was press-molded (vulcanized) under the conditions of 150 °C × 20 minutes to prepare a rubber sheet with a thickness of 2 mm. Then, in order to evaluate the flammability of this rubber sheet, in accordance with JIS K7201, the minimum oxygen concentration (volume %) required to sustain the combustion of this rubber sheet, that is, the oxygen index, was measured. And those with the above oxygen index of 22 volume % or more were evaluated as "◎ (excellent)", those with a value of 20 volume % or more and less than 22 volume % as "〇 (very good)", those with a value of 19 volume % or more and less than 20 volume % as "△ (good)", and those with a value less than 19 volume % as "× (poor)".

[0082] ≪Vibration Isolation Performance≫ Each anti-vibration rubber composition was press-molded (vulcanized) under the conditions of 150 °C × 30 minutes to prepare a test piece in a cylindrical shape (diameter 50 mm, height 25 mm). Circular metal fittings (diameter 60 mm, thickness 6 mm) were respectively attached to the upper and lower surfaces thereof, and the dynamic spring constant (Kd100) and the static spring constant (Ks) were measured in accordance with JIS K6394 respectively. Based on those values, the dynamic magnification ratio (Kd100 / Ks) was calculated. And as an evaluation of the vibration isolation performance, those with a dynamic magnification ratio of 1.6 or less were evaluated as "〇 (very good)", those with a dynamic magnification ratio exceeding 1.6 and less than 2 as "△ (good)", and those with a dynamic magnification ratio of 2 or more as "× (poor)".

[0083]

Table 1

[0084]

Table 2

[0085] As is clear from the results in Table 1 above, the rubber composition of the example is excellent in flame retardancy evaluation (light transmittance, oxygen index), and excellent effects are obtained in vibration isolation performance (vibration isolation rubber characteristics) and tensile physical properties (rubber physical properties (TB, EB) in dumbbell tensile test). On the other hand, as shown in Table 2 above, the rubber composition of the comparative example is different from the rubber composition of the example, and shows an evaluation of "× (poor)" in one or more evaluation items. That is, since the rubber composition of Comparative Example 1 does not contain a dihydrazide compound, the dispersibility of aluminum hydroxide is poor, the value of ΔG' does not show a desired value, and the vibration isolation performance and tensile physical properties are inferior. In Comparative Example 2, although the addition amount of the dihydrazide compound is more than the specified amount of the present invention and it is excellent in flame retardancy evaluation, the rubber is hard, resulting in inferior tensile physical properties and vibration isolation performance. In Comparative Example 3, the addition amount of carbon black is less than the specified amount of the present invention, and although it is excellent in flame retardancy evaluation, the reinforcing property of the rubber is low and the tensile physical properties and vibration isolation performance are inferior. In Comparative Example 4, the addition amount of carbon black is more than the specified amount of the present invention, and although it is excellent in flame retardancy evaluation, the rubber hardness becomes high, resulting in inferior tensile physical properties and vibration isolation performance. In Comparative Example 5, the addition amount of aluminum hydroxide is less than the specified amount of the present invention, and although it is excellent in vibration isolation performance, the flame retardancy evaluation is inferior. In Comparative Example 6, the addition amount of aluminum hydroxide is more than the specified amount of the present invention, and although it is excellent in flame retardancy evaluation, the value of ΔG' does not show a desired value, resulting in inferior tensile physical properties and vibration isolation performance. In Comparative Example 7, since no metal hydroxide is contained, although it is excellent in vibration isolation performance, the flame retardancy evaluation is inferior. In Comparative Example 8, since no carbon black is contained, the dispersibility of aluminum hydroxide is poor and the reinforcing property of the rubber is low, resulting in inferior vibration isolation performance and tensile physical properties.

[0086] In addition, in the above examples, specific forms in the present invention were shown, but the above examples are merely illustrative and are not to be construed in a limiting sense. Various modifications obvious to those skilled in the art are intended to be within the scope of the present invention.

Industrial Applicability

[0087] This anti-vibration rubber composition is preferably used as a material for, for example, engine mounts, stabilizer bushes, suspension bushes, etc. used in vehicles such as automobiles and trains. In addition, it can also be used as a material for vibration damping dampers for computer hard disks, vibration damping dampers for general household appliances such as washing machines, vibration damping (vibration isolation) devices such as building seismic walls and vibration damping (vibration isolation) dampers in the construction and housing fields, and components (anti-vibration rubber members) of seismic isolation devices.

Claims

1. A flame-retardant vibration-damping rubber composition containing the following (A) to (D), wherein, based on 100 parts by mass of the following (A), the proportion of the following (B) is 20 to 150 parts by mass, the proportion of the following (C) is 0.01 to 5.0 parts by mass, the proportion of the following (D) is 10 to 80 parts by mass, and ΔG' represented by the following formula (i) is less than 2.3: a flame-retardant vibration-damping rubber composition. (A) Dienic rubber. (B) Metal hydroxide. (C) Dihydrazide compound. (D) Carbon black. ΔG' = G'2 / G'1 …… (i) [In formula (i), G'1 is the storage modulus of the above flame-retardant vibration-damping rubber composition at a frequency of 11 Hz, a strain of 42%, and 40°C, and G'2 is the storage modulus of the above flame-retardant vibration-damping rubber composition at a frequency of 11 Hz, a strain of 0.28%, and 40°C.]

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

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

4. The flame-retardant vibration-damping rubber composition according to any one of claims 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.

5. A flame-retardant vibration-damping rubber member comprising a vulcanizate of the flame-retardant vibration-damping rubber composition according to any one of claims 1 to 4.

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