Rubber composition for exhaust mount, and exhaust mount

Abstract

To provide a rubber composition for an exhaust mount that has excellent durability and thermal aging resistance in a high-temperature atmosphere, and excellent thermal settling resistance, and that is superior in also durability after thermal aging, and to provide an exhaust mount.SOLUTION: A molded body 1 of an exhaust mount composed of a rubber elastic body is provided with a vehicle body-side fitting hole 2A and an exhaust pipe-side fitting hole 2B for vibration-dampingly supporting the exhaust pipe in a suspended state with respect to a vehicle body. The molded body uses a rubber composition for an exhaust mount in which an ethylene-α-olefin-non-conjugated polyene copolymer is used as a main rubber component, and which contains an organic peroxide, silicone oil, and a benzimidazole-based antioxidant in a specific ratio.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rubber composition for exhaust mounts which can be applied to, for example, support locations of exhaust pipes for automobiles, and which has excellent durability, heat aging resistance, and heat setting resistance in high-temperature environments, as well as excellent durability after heat aging, and to an exhaust mount using this rubber composition. [Background technology]

[0002] For example, the exhaust pipe of an automobile becomes hot when exhaust gas from the engine passes through it. In particular, when the engine is in a high-output, high-speed state, the amount of fuel is increased and hotter exhaust gas passes through the exhaust pipe, so the temperature in the exhaust pipe tends to become extremely high.

[0003] Furthermore, as exhaust gas regulations become stricter, there is a demand for improving the efficiency of catalysts in the exhaust pipe. In this case, the catalyst needs to function at high temperatures in the exhaust pipe, so the temperature tends to become higher.

[0004] Furthermore, in recent years, there has been a demand for installing a filter such as a gasoline particulate filter (GPF) in the exhaust passage of the exhaust pipe to capture particulate matter (PM) in the exhaust gas and suppress its release to the outside. Because the filter is prone to becoming clogged with the captured particulate matter, a regeneration process (PM regeneration) is carried out to burn and remove the particulate matter, but this makes the exhaust pipe more susceptible to being exposed to high temperatures for long periods of time.

[0005] Incidentally, in the exhaust pipes of automobiles, exhaust mounts (rubber elastic bodies also called muffler hangers or exhaust pipe supports) made of rubber elastic bodies that can support the exhaust pipes in a suspended state from the vehicle body in an anti-vibration manner are used. Therefore, as mentioned above, if the exhaust pipes are exposed to high temperatures for a long time, the vicinity of the exhaust mounts will also be exposed to high temperatures for a long time.

[0006] As mentioned above, the exhaust mount is configured to support the exhaust pipe in a suspended state in an anti-vibration manner and to expand and contract (for example, to a greater extent than other anti-vibration rubber parts which are more likely to be subjected to heavy loads) in response to vibrations in the vehicle body. When rubber parts such as exhaust mounts are exposed to high temperatures for long periods of time, deterioration accelerates, which not only deteriorates their vibration-proofing properties, but also causes them to expand and contract significantly in this deteriorated state and break, causing them to lose their functions as anti-vibration rubber. Furthermore, in a high-temperature atmosphere, durability is also likely to decrease significantly due to repeated expansion and contraction.

[0007] In order to prevent the various functions of anti-vibration rubber from being reduced due to thermal degradation of the rubber or reduced durability in high-temperature environments, measures have been taken, such as placing a heat shield between the exhaust mount and the exhaust pipe to prevent heat from the exhaust pipe from reaching the exhaust mount and causing a rise in temperature, but placing a separate heat shield is a factor that leads to increased costs.

[0008] Incidentally, in the exhaust mounts described above, rubber elastomers made of sulfur-vulcanized rubber compositions using ethylene-α-olefin-non-conjugated polyene copolymers such as EPDM as the main rubber component and sulfur or a sulfur compound as a cross-linking agent (vulcanizing agent) have been used in consideration of the balance between rubber strength, heat resistance, vibration-proofing properties, and fatigue resistance. However, due to the deterioration of the thermal environment in the vicinity of the exhaust mount placement location, high heat resistance is also required for the exhaust mount. For this reason, the emergence of rubber compositions with significantly improved heat resistance compared to rubber compositions that simply use EPDM as the rubber component as described above is desired.

[0009] In view of this, a proposal has been made to improve the heat resistance time in a 150°C atmosphere by using a p-phenylenediamine compound having a double bond at the end as an anti-aging agent for an EPDM rubber composition (Patent Document 1).

[0010] Generally, the usable temperature range of rubber elastomers made of EPDM rubber compositions is said to be approximately -60 to 150°C (Non-Patent Document 1), but from the perspective of rubber compositions for exhaust mounts, it is desirable to further improve the heat resistance temperature.

[0011] In response to this, attempts have been made to use silicone rubber, which has excellent heat resistance, as a rubber elastic body for exhaust mounts. Silicone rubber has high heat resistance and is less susceptible to deterioration even when exposed to high-temperature atmospheres well above 150°C for long periods of time. However, silicone rubber has extremely low rubber strength in high-temperature atmospheres and may be prone to breakage if it is elastically deformed (e.g., significantly deformed) in a high-temperature atmosphere, so there are issues with using it in exhaust mounts that can expand and contract significantly due to vibrations of the vehicle body.

[0012] Furthermore, a method of using a peroxide such as dicumyl peroxide (DCP) as a crosslinking agent is known as a method for improving the heat resistance of rubber elastomers made from ethylene-α-olefin-non-conjugated polyene copolymers. However, compared with rubber elastomers vulcanized with sulfur, peroxide-vulcanized rubber elastomers tend to have lower rubber strength and tear strength, and to have inferior durability such as dynamic fatigue resistance. To address this issue, a method has been proposed in which an ethylenically unsaturated carboxylic acid metal salt is used as a reinforcing agent (Patent Document 2). Furthermore, to address the issue of insufficient heat resistance when used in a thermal environment significantly exceeding 150°C, it has been proposed to use an ethylene-α-olefin-non-conjugated polyene copolymer that contains a non-conjugated polyene such as 5-vinyl-2-norbornene (VNB) as a copolymerization component and has a low content of long chain branches, and to crosslink the copolymer using a peroxide. This is said to make it easier to increase the crosslink density, resulting in anti-vibration rubber products (such as muffler hangers) that have excellent vibration-proof properties, sufficient strength, and excellent heat resistance (Patent Document 3). [Prior art documents] [Patent documents]

[0013] [Patent Document 1] JP 2001-181458 A [Patent Document 2] JP 2005-126473 A [Patent Document 3] Re-tabled publication No. 2019-180802 (Patent No. 6941225) [Non-patent literature]

[0014] [Non-Patent Document 1] "New Edition Fundamentals of Rubber Technology, Revised Edition, 105 pages," edited by the Society of Rubber Science and Technology of Japan, published by the Society of Rubber Science and Technology of Japan, a general incorporated foundation, revised 5th printing published on June 10, 2019. Summary of the Invention [Problem to be solved by the invention]

[0015] When such a rubber composition is used in an exhaust mount, there is a problem that it is likely to be insufficient to satisfy all of the desired durability, heat aging resistance, heat setting resistance, and durability after heat aging in a high temperature atmosphere (e.g., above 150°C).

[0016] That is, the vibration-proof rubber made using the rubber composition (EPDM vulcanized rubber) described in Patent Document 1 has not been examined for heat resistance significantly exceeding 150° C. or durability in high-temperature environments, and therefore there is a risk that the heat resistance will be insufficient when used in a thermal environment exceeding 150° C.

[0017] The rubber composition described in Patent Document 2 has not been examined for its heat resistance above 150° C. For this reason, an exhaust mount (vulcanized rubber elastomer) made using this rubber composition may have insufficient vibration durability after heat aging above 150° C. and in a heat environment above 150° C.

[0018] Anti-vibration rubber made using the rubber composition described in Patent Document 3 may have excellent heat aging resistance when used as an exhaust mount, but the rubber strength is likely to be low and there is a risk that durability in high temperature environments (for example, durability when greatly deformed) may be poor.

[0019] An object of the present invention is to provide a rubber composition for exhaust mounts and an exhaust mount which have excellent durability, heat aging resistance, and heat setting resistance in high-temperature environments (e.g., above 150°C), and which also have excellent durability after heat aging. [Means for solving the problem]

[0020] As a result of intensive research by the inventors to solve the above-mentioned problems, they have discovered that in an exhaust mount made of a rubber elastomer, by using a rubber composition which contains an ethylene-α-olefin-non-conjugated polyene copolymer as the main rubber component, and which also contains an organic peroxide, silicone oil, and a benzimidazole-based antioxidant in specific proportions, it is possible to obtain an exhaust mount which has excellent durability, heat aging resistance, and heat setting resistance even in high temperature environments of, for example, above 150°C, and which also has excellent durability after heat aging, and have thus completed the present invention.

[0021] That is, one embodiment of the rubber composition for exhaust mount of the present invention is as follows: [1] to [6].

[0022] [1] A rubber composition comprising an ethylene-α-olefin-non-conjugated polyene copolymer as a main rubber component, the rubber composition comprising 90 to 100 parts by mass of the ethylene-α-olefin-non-conjugated polyene copolymer, 1.5 to 4.5 parts by mass of an organic peroxide, and a rubber composition having a kinetic viscosity of 20 mm at 25°C, when the total rubber component is 100 parts by mass. 2 1. A rubber composition for exhaust mounts, comprising: 1 to 15 parts by mass of a silicone oil having a viscosity of 100 / s or more; and 2 to 8 parts by mass of a benzimidazole-based antioxidant.

[0023] [2] The kinetic viscosity of the silicone oil (25°C) is 40 to 600 mm 2The rubber composition for exhaust mounts according to [1], characterized in that:

[0024] [3] The rubber composition for exhaust mounting according to [1], wherein the organic peroxide is dicumyl peroxide.

[0025] [4] A rubber composition for exhaust mounting according to any one of [1] to [3], characterized in that, relative to 100 parts by mass of the total rubber components, an oil component other than silicone oil is contained as a softener in an amount of 20 to 100 parts by mass, the oil component being paraffin-based oil and / or ethylene-α-olefin copolymer-based hydrocarbon-based synthetic oil, and the aniline point of the oil component being 120°C or higher.

[0026] [5] The ethylene-α-olefin-non-conjugated polyene copolymer has an ethylene content of 63 to 75% by mass and a Mooney viscosity (ML 1+4 ) is 60 to 200.

[0027] [6] A rubber composition for exhaust mounts according to any one of [1] to [5], characterized in that it contains 30 to 70 parts by mass of carbon black having an iodine adsorption amount of 20 to 30 (mg / g) and a DBP absorption amount of 100 to 150 (ml / 100 g) relative to 100 parts by mass of the total rubber component.

[0028] Another aspect of the exhaust mount of the present invention is as follows [7].

[0029] [7] An exhaust mount made of a rubber elastomer having mounting holes into which a mounting pin on a vehicle body side and a mounting pin on an exhaust pipe side are inserted, and which is interposed between the vehicle body and the exhaust pipe to provide vibration-damping support for the exhaust pipe in a suspended state relative to the vehicle body, wherein the rubber elastomer is formed by crosslinking the rubber composition for exhaust mounts described in any one of [1] to [6]. Effect of the Invention

[0030] The present invention can contribute to providing a rubber composition for exhaust mounts and an exhaust mount that have excellent durability, heat aging resistance, and heat setting resistance in high-temperature environments (e.g., above 150°C), and that also have excellent durability after heat aging. [Brief description of the drawings]

[0031] [Figure 1] 1 is a perspective view showing a molded exhaust mount body 1 produced using each of the rubber compositions of Examples 1 to 22 and Comparative Examples 1 to 10. FIG. [Diagram 2] FIG. 2 is a plan view of the molded body 1 shown in FIG. [Diagram 3] 3 is a cross-sectional view of the molded body 1 shown in FIG. 2, which corresponds to the cross section AA in FIG. [Figure 4] 2 is a plan view showing a state in which a measurement jig J is attached for vibration characteristic measurement and vibration endurance testing of the molded body 1 shown in FIG. 1. [Diagram 5] 5 is a diagram (partial cross-sectional view) showing a state in which a measuring jig J is attached to the molded body 1 shown in FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Matters relating to the implementation of the present invention will be described in detail below.

[0033] As described above, the rubber composition for exhaust mounts according to the present invention (hereinafter simply referred to as rubber composition) contains at least 90 to 100 parts by mass of an ethylene-α-olefin-non-conjugated polyene copolymer, 1.5 to 4.5 parts by mass of an organic peroxide, and a 25° C. kinematic viscosity of 20 mm 2 The rubber composition for exhaust mounts contains 1 to 15 parts by mass of silicone oil having a viscosity of 100 / s or more and 2 to 8 parts by mass of a benzimidazole-based antioxidant. That is, the rubber composition for exhaust mounts is made of a rubber elastomer obtained by crosslinking an ethylene-α-olefin-non-conjugated polyene copolymer with a peroxide.

[0034] <Example of consideration> [When peroxide crosslinking is applied] It is known that rubber compositions obtained by crosslinking ethylene-α-olefin-non-conjugated polyene copolymers with peroxides have superior heat resistance compared to rubber compositions obtained by crosslinking the ethylene-α-olefin-non-conjugated polyene copolymers with sulfur.

[0035] Therefore, we created an exhaust mount molded body (hereinafter simply referred to as the verification molded body) using a rubber elastomer obtained by simply crosslinking a rubber composition containing an ethylene-α-olefin-non-conjugated polyene copolymer and an organic peroxide, and conducted durability tests in a high-temperature atmosphere of 180°C or more as appropriate (vibration durability tests, breaking tests, etc. were conducted on a large number of pieces).

[0036] In addition, the verification molded body was provided with a mounting hole into which a mounting pin on the vehicle body side could be inserted and a mounting hole into which a mounting pin on the exhaust pipe side could be inserted, so that the exhaust pipe could be supported in a suspended state in a vibration-proof manner relative to the vehicle body (for example, as shown in Figures 1 to 3 described below). In addition, the durability test was performed by inserting metal collars (corresponding to mounting pins) into each mounting hole of the verification molded body, and fixing each metal collar to a measuring jig of a durability test machine (for example, fixing to a metal measuring jig J as shown in Figures 4 and 5 described below).

[0037] As a result of carrying out a durability test on this verification molded body, it was found that the wall portion of the verification molded body broke. However, it was found that all of the breaking phenomena originated from the hole wall portion constituting the mounting hole (for example, the hole wall portions indicated by the symbols 21A and 21B in Figures 1 to 3 and Figure 5 described below).

[0038] In the case of exhaust mounts made from EPDM elastomer obtained by general sulfur vulcanization, when vibration endurance tests are similarly conducted in a high-temperature atmosphere, the phenomenon in which the wall ruptures tends to originate from a part of the wall of the exhaust mount other than the hole wall (for example, side wall 3 of wall 10 in Figures 1 to 5 described below; hereinafter, simply referred to as the part other than the hole wall).

[0039] In general, ethylene-α-olefin-non-conjugated polyene copolymers have a lower adhesion between unvulcanized rubbers than diene rubbers such as natural rubber, depending on the molecular weight (polymer viscosity) and the compounding materials and content of the composition, and it can be said that the fusion property when unvulcanized rubbers are pasted together is also low. In addition, for example, rubber compositions injected into a high-temperature mold cavity by injection or the like are usually injected (filled) into the mold cavity at a molding temperature of 80°C or higher. For this reason, in sulfur-vulcanized rubber compositions, the crosslinking (vulcanization) reaction often starts relatively early.

[0040] On the other hand, in the case of a rubber composition using an organic peroxide, even if the molding temperature is 80°C or higher, as long as it is approximately 120°C or lower, it is possible to easily set various conditions, such as maintaining a state in which the crosslinking reaction does not start (hereinafter simply referred to as an unreacted state at the molding temperature) and appropriately setting the time required from the unreacted state at the molding temperature to the start of the crosslinking reaction (for example, setting it to be extremely long).

[0041] Therefore, even after a rubber composition using an organic peroxide is injected and filled into a mold cavity, it is easy to control the rubber composition so that it remains in an unreacted state at molding temperature and under pressure for a relatively long time in the mold cavity. For this reason, even in a rubber composition using an ethylene-α-olefin-non-conjugated polyene copolymer, which tends to have low adhesion and fusion properties between unvulcanized rubber particles, if the rubber composition can be kept in an unreacted state at molding temperature at a relatively high temperature for a long time, the unvulcanized rubber particles will fuse together sufficiently, and the occurrence of microscopic internal defects (fusion defects) is suppressed.

[0042] For the reasons described above, it is believed that the microscopic internal defects in the wall of the verification molded body were suppressed, and the phenomenon of fracture originating from anywhere other than the hole wall did not occur in the durability test described above.

[0043] On the other hand, it is believed that the phenomenon in which the fracture started from the hole wall of the verification molded body occurred because severe friction occurred between the hole wall and the metal collar inserted into the mounting hole when the verification molded body was repeatedly subjected to large elastic deformation during vibration endurance tests, etc.

[0044] [When antioxidant is applied] For example, in the case of a rubber elastomer obtained by crosslinking an ethylene-α-olefin-non-conjugated polyene copolymer that does not contain antioxidants with organic peroxides, if it is exposed to high temperatures exceeding 150°C, the peroxide residues that may remain in the rubber elastomer may act as strong oxidizing agents, causing rapid molecular scission and deterioration. In order to suppress such deterioration due to molecular scission, a method of appropriately applying antioxidants is adopted.

[0045] The present inventors have found through their investigations that a rubber elastic body made using a rubber composition containing a certain amount of a benzimidazole-based antioxidant, among other antioxidants, is inhibited from softening and deteriorating.

[0046] However, when a molded product for verification was created by peroxide cross-linking an ethylene-α-olefin-non-conjugated polyene copolymer containing a benzimidazole-based antioxidant and repeatedly subjected to large elastic deformation in a vibration durability test in a high-temperature atmosphere exceeding 150°C, cracks occurred starting from the wall of the mounting hole, and it was difficult to prevent breakage.

[0047] [When combined with antioxidant and silicone oil] Next, a specific amount of silicone oil and a benzimidazole-based antiaging agent were added to a rubber composition containing an ethylene-α-olefin-non-conjugated polyene copolymer and an organic peroxide, and the rubber composition was crosslinked (peroxide crosslinked) to obtain a rubber elastomer, which was then used to create a molded body similar to the verification molded body (hereinafter simply referred to as the improved molded body) and then verified.

[0048] First, we conducted vibration durability tests in a high-temperature atmosphere on the improved molded body in the same way as the verification molded body, and found that the occurrence of cracks originating from the hole wall was suppressed or prevented, and that the vibration durability in a high-temperature atmosphere was significantly improved.

[0049] That is, it was found that the durability (vibration durability) of the improved molded body in a high-temperature atmosphere was dramatically improved compared to the verification molded body. The reason for this improvement in durability can be presumed as follows.

[0050] For example, when a friction test was carried out at room temperature on a rubber elastomer made using a rubber composition containing 1 to 10 parts by mass of silicone oil, the stick-slip phenomenon occurred, just as in the case of a rubber elastomer made of a rubber composition not containing silicone oil, and no clear effect of reducing the friction coefficient was observed.

[0051] On the other hand, in the case of the improved molded body, when it is elastically deformed in a high-temperature atmosphere exceeding 150°C, the silicone oil seeps out, albeit slightly (the bleeding phenomenon occurs). This is thought to have significantly reduced the friction between the hole wall and the metal collar inserted into the mounting hole, dramatically improving durability (number of breaks) in vibration durability tests in a high-temperature atmosphere.

[0052] It has been confirmed that even if the rubber composition used for the improved molded body contains silicone oil as described above, if it does not contain a benzimidazole-based antioxidant, sufficient vibration durability in a high-temperature atmosphere cannot be obtained.

[0053] <Example of rubber composition and exhaust mount according to the present invention> Each component of the rubber composition applicable to the molded exhaust mount according to the present invention will be described below.

[0054] In the following description, when the content of all materials is indicated, it may simply be expressed as parts by mass, but this means the parts by mass of each material when the total rubber component is taken as 100 parts by mass.

[0055] [Rubber component] In the rubber composition according to the present invention, an ethylene-α-olefin-non-conjugated polyene copolymer is used as the main rubber component in the rubber component. The main rubber component means that 90 parts by mass or more of the total rubber component is an ethylene-α-olefin-non-conjugated polyene copolymer, and it is preferable that 95 parts by mass or more of the total rubber component is an ethylene-α-olefin-non-conjugated polyene copolymer, and it is more preferable that 98% by mass or more of the total rubber component is an ethylene-α-olefin-non-conjugated polyene copolymer. In addition to simply containing an ethylene-α-olefin-non-conjugated polyene copolymer, it is also possible to contain a small amount of other rubber components for the purpose of improving processability, or to contain a small amount of other rubber components as a binder used in a master batch of a vulcanization accelerator or a crosslinking agent.

[0056] The ethylene-α-olefin-non-conjugated polyene copolymer is not particularly limited, but the ethylene content of the ethylene-α-olefin-non-conjugated polyene copolymer is preferably in the range of 50 to 75 (mass %). When two or more types of ethylene-α-olefin-non-conjugated polyene copolymers are blended for use, the ethylene content means the average ethylene content (mass %) calculated by considering the ethylene-α-olefin-non-conjugated polyene copolymer after blending as one ethylene-α-olefin-non-conjugated polyene copolymer and calculating the mass ratio. Furthermore, the Mooney viscosity (ML 1+4 ) is preferably in the range of 60 to 200.

[0057] One of the characteristics required for an exhaust mount is to improve the comfort of passengers inside the vehicle. For this reason, it is required to be able to block and suppress the transmission of vibration from the exhaust pipe, which is the source of vibration, and reduce the intrusion of vibration and noise into the vehicle. It is known that reducing the dynamic spring constant (Kd) is effective in improving the vibration isolation performance of an exhaust mount, that is, in blocking the transmission of vibration.

[0058] However, since exhaust mounts are required to withstand a certain static force so that they can support an exhaust pipe of a certain weight in a suspended state from the vehicle body, the static spring characteristic (Ks) must be relatively large. Therefore, it is desirable for the dynamic magnification (=Kd / Ks), which is the ratio of the dynamic spring constant (Kd) to the static spring constant (Ks), to be small (i.e., a low dynamic magnification). Furthermore, it is desirable for exhaust mounts to have high durability against elastic deformation caused by repeated vibrations.

[0059] As described above, the ethylene content is within the range of 50 to 75 (mass%) and the Mooney viscosity at 125°C (ML 1+4 ) is within the range of 60 to 200, it is preferable because high vibration characteristics and durability against elastic deformation due to repeated vibration can be obtained.

[0060] Examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicosene. Among these, α-olefins having 3 to 8 carbon atoms such as propylene, 1-butene, 1-hexene, and 1-octene are preferred, and propylene is particularly preferred. As for propylene, many products with different Mooney viscosities and different ethylene contents are commercially available at relatively low prices, making it easy to obtain and easy to select a copolymer taking into account the product characteristics and productivity of the exhaust mount.

[0061] Examples of non-conjugated polyenes include 5-ethylidene-2-norbornene (ENB), 5-vinyl-2-norbornene (VNB), 5-methylene-2-norbornene, 5-(2-propenyl)-2-norbornene, 5-(3-butenyl)-2-norbornene, 5-(1-methyl-2-propenyl)-2-norbornene, 5-(4-pentenyl)-2-norbornene, 5-(1-methyl-3-butenyl)-2-norbornene, 5-(5-hexenyl)-2-norbornene, 5-(1-methyl-4-pentenyl)-2-norbornene, 5-(2,3-dimethyl-3-butenyl)-2-norbornene, 5-(2-ethyl ... 5-ethyl-3-butenyl)-2-norbornene, 5-(6-heptenyl)-2-norbornene, 5-(3-methyl-5-hexenyl)-2-norbornene, 5-(3,4-dimethyl-4-pentenyl)-2-norbornene, 5-(3-ethyl-4-pentenyl)-2-norbornene, 5-(7-octenyl)-2-norbornene, 5-(2-methyl-6-heptenyl)-2-norbornene, 5-(1,2-dimethyl-5-hexenyl)-2-norbornene, 5-(5-ethyl-5-hexenyl)-2-norbornene, 5-(1,2,3-trimethyl-4-pentenyl)-2-norbornene, etc. Among these, 5-ethylidene-2-norbornene (ENB) is preferred. With regard to 5-ethylidene-2-norbornene (ENB), many products with different Mooney viscosities and different ethylene contents are commercially available at relatively low cost, making it easy to obtain and easy to select a copolymer taking into account the product characteristics and productivity of the exhaust mount.

[0062] Here, when two or more types of ethylene-α-olefin-non-conjugated polyene copolymers are blended and used, the ethylene-α-olefin-non-conjugated polyene copolymer after blending is regarded as one ethylene-α-olefin-non-conjugated polyene copolymer (A) and the average ethylene content (mass%) calculated by the mass ratio is meant.

[0063] In addition, the Mooney viscosity (ML 1+4) is the Mooney viscosity (ML 1+4 ) for ethylene-α-olefin-non-conjugated polyene copolymers. 1+4 If the viscosity of the paraffin oil is high, for example, when it is molded into a veil-like product, it may be difficult to maintain the veil shape, and handling properties may be poor (for example, scattering during cutting or difficulty in feeding into a kneading machine). Therefore, the paraffin oil is often sold in a paraffin oil-impregnated state (oil-extended state).

[0064] The ethylene-α-olefin-non-conjugated polyene copolymer (A) here refers to the Mooney viscosity (ML 1+4 ) is the Mooney viscosity (ML) when no paraffin oil is added (unextended state) 1+4 When two or more types of ethylene-α-olefin-non-conjugated polyene copolymers are blended, the average Mooney viscosity (ML 1+4 )

[0065] [Crosslinking Agent] The rubber composition according to the present invention contains an organic peroxide as a crosslinking agent, which is an essential component. As the organic peroxide, for example, a conventionally known organic peroxide that is usually used in crosslinking rubber can be appropriately used. Specifically, dicumyl peroxide, di-t-butyl peroxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylcumyl peroxide, di-t-amyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexane, α,α'-bis(t-butylperoxy-m-isopropyl peroxide), ... Examples of organic peroxides include alkyl peroxides such as diisopropyl)benzene and t-butyl hydroperoxide, peroxyesters such as t-butyl peroxy acetate, t-butyl peroxy isobutyrate, t-butyl peroxy pivalate, t-butyl peroxy maleic acid, t-butyl peroxy neodecanoate, t-butyl peroxy benzoate, and di-t-butyl peroxy phthalate, and ketone peroxides such as dicyclohexanone peroxide. These organic peroxides can be used alone or in combination of two or more. Among these organic peroxides, those having a one-minute half-life temperature of 130 to 200°C are preferred, such as dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexane, di-t-butyl peroxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butyl cumyl peroxide, di-t-amyl peroxide, and t-butyl hydroperoxide. Among these, dicumyl peroxide is more preferred because it is easy to obtain a highly crosslinked rubber elastomer, fusion is unlikely to occur during injection molding (vulcanization is unlikely to progress at temperatures below 140°C), and productivity (crosslinking temperature) is not too high.

[0066] The content of the organic peroxide in the rubber composition according to the present invention can be appropriately set, but for example, from the viewpoint of obtaining the desired physical properties by sufficient crosslinking and suppressing the adverse effects of excess decomposition products, it is set to be within the range of 1.5 to 3.5 parts by mass when the total rubber component is taken as 100 parts by mass, and preferably within the range of 2 to 3 parts by mass.

[0067] In addition, organic peroxides are often commercially available after being appropriately diluted (usually about 20% to 50%) for reasons such as reducing risk and improving kneading processability. The content of organic peroxide in the present invention means the content when the organic peroxide is taken as 100%. For example, when the content of dicumyl peroxide (DCP-40) diluted to a concentration of 40% is 6 mass, the content as organic peroxide is 2.4 mass parts. From the viewpoints of improving kneading processability, metering ability, storage stability, safety, etc., a master batch of organic peroxide diluted to a concentration of 30 to 40 mass% is preferably used.

[0068] The rubber composition according to the present invention may contain the crosslinking agent described above and may also contain a crosslinking aid as another crosslinking agent component. Examples of the crosslinking aid include sulfur, quinone dioxime crosslinking aids such as p-quinone dioxime, acrylic crosslinking aids such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate, allyl crosslinking aids such as diallyl phthalate and triallyl isocyanurate, other maleimide crosslinking aids, and divinylbenzene. The amount of the crosslinking aid used in the case of using such a crosslinking aid can be appropriately set, but is usually about 0.1 to 10 moles per mole of organic peroxide.

[0069] [Silicone oil] The rubber composition according to the present invention contains silicone oil as an essential component. Various types of silicone oil are known. 2As long as the viscosity of the silicone oil is 1 / s or more, it can be used appropriately without any particular limitation. Examples of such silicone oils include straight silicone oils such as dimethyl silicone oil, methylphenyl silicone oil, and methylhydrogen silicone oil, and modified silicone oils such as reactive silicone oil and non-reactive silicone oil.

[0070] Silicone oil has a kinetic viscosity of 20mm 2 If the kinetic viscosity is less than 30 mm / s, there is a risk of excessive volatilization in a high-temperature atmosphere, which is not good. On the other hand, if the kinetic viscosity is too high, there is a risk that precipitation on the surface of the rubber elastomer will be too suppressed even in a high-temperature atmosphere. Therefore, the kinetic viscosity of the silicone oil is set to be less than 30 mm / s. 2 / s or more 5000mm 2 From the viewpoint of making it easier to obtain an exhaust mount that has little volatilization of the silicone oil and has excellent durability in a high-temperature atmosphere, the kinetic viscosity of the silicone oil is more preferably 40 mm / s or less. 2 / s or more 600mm 2 / s or less.

[0071] The unit of kinematic viscosity is mm 2 / s may be expressed as cS or cSt (centistokes), but they are units that indicate the same value (i.e. mm 2 / s=cS).

[0072] The content of the silicone oil can be appropriately set, but for example, when the total rubber components are 100 parts by mass, it can be set to a range of 1 to 15 parts by mass. Within this range, it is possible to obtain an exhaust mount that has good kneading processability and excellent vibration durability even in a high-temperature atmosphere. The content of the silicone oil is preferably 2 to 12 parts by mass, and more preferably 4 to 10 parts by mass.

[0073] If the content of silicone oil exceeds 15 parts by mass, the cohesion of the uncrosslinked rubber tends to deteriorate significantly. In addition, for example, when roll processing is performed, the uncrosslinked rubber composition tends to be difficult to wind around the roll due to a slip phenomenon, and kneading processability may deteriorate.

[0074] [Anti-aging agent] The rubber composition according to the present invention contains a benzimidazole-based antioxidant as an essential antioxidant. This benzimidazole-based antioxidant is known as a secondary antioxidant, and in sulfur-vulcanized rubber compositions, it is often used in combination with various amine-based antioxidants and phenol-based antioxidants, which are primary antioxidants.

[0075] As described above, the rubber composition according to the present invention contains an ethylene-α-olefin-non-conjugated polyene copolymer as the main rubber component, and is crosslinked using a peroxide to obtain a rubber elastomer, but it is difficult to completely remove the peroxide residues and unreacted peroxides that may be present in the rubber. Moreover, the peroxide residues and unreacted peroxides act as strong oxidizing agents in a hot atmosphere exceeding 150°C, and may accelerate the deterioration of the crosslinked rubber, such as by causing molecular scission of the rubber elastomer.

[0076] Therefore, when improving the heat aging resistance of peroxide-crosslinked ethylene-α-olefin-non-conjugated polyene copolymers, it is effective to add a benzimidazole-based antioxidant.

[0077] The content of the benzimidazole-based antioxidant can be appropriately set, for example, in the range of 2 to 8 parts by mass, which is higher than the content used in a normal ethylene-α-olefin-non-conjugated polyene copolymer composition. If it is within such a range, it is possible to obtain a rubber composition that is excellent in vibration durability in a high-temperature atmosphere of an exhaust mount and vibration durability after heat aging, and is also excellent in heat aging resistance and compression set rate.

[0078] In order to suppress the influence of heat aging (for example, changes due to elongation at break), the benzimidazole-based antioxidant may be contained in an amount of more than 8 parts by mass, but if it is contained in an excessive amount, the compression set rate may tend to deteriorate. From this viewpoint, the preferred content of the benzimidazole-based antioxidant is 3 to 6 parts by mass.

[0079] When a benzimidazole-based antioxidant is included, the vibration durability of the exhaust mount in a high-temperature atmosphere is improved. The reason for this is that when a vibration durability test is performed in a high-temperature atmosphere exceeding 150°C, the friction coefficient of the wall of the mounting hole of a normal exhaust mount may increase due to softening and deterioration of the crosslinked rubber on the surface, but as described above, a rubber composition containing a benzimidazole-based antioxidant can be expected to have the effect of suppressing the increase in the friction coefficient. As a result, it can be expected that even if a mounting pin (metal pin) is inserted into the mounting hole and a crack is likely to occur starting from the hole wall, the occurrence of the crack can be sufficiently suppressed.

[0080] As the benzimidazole-based antiaging agent, a conventionally known one can be appropriately used, and preferred ones include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, and zinc salt of 2-mercaptobenzimidazole. In the rubber composition according to the present invention, the benzimidazole-based antioxidants shown above may be used in combination with other antioxidants than the benzimidazole-based antioxidants, for example, an amine-based antioxidant or a phenol-based antioxidant may be used in combination.

[0081] In this way, even when other antioxidants such as amine-based antioxidants and phenol-based antioxidants are used in combination, the effect of improving heat aging resistance can be obtained, but when an organic peroxide is used as a crosslinking agent, crosslinking may be inhibited. This is thought to occur because the antioxidant traps polymer radicals generated in the crosslinking process by the action of the organic peroxide. For this reason, when using an amine-based antioxidant or a phenol-based antioxidant in combination, it is preferable to use 1 part by mass or less per 100 parts by mass of the total rubber component.

[0082] Considering the balance of physical properties such as heat aging resistance and compression set resistance, preferred examples of antioxidants other than benzimidazole-based antioxidants include 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (DCD), N-phenyl-1-naphthylamine (PAN), N,N'-di-2-naphthyl-p-phenylenediamine (DNPD), and bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid][2,2-bis[[1-oxo-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propoxy]methyl]propane]-1,3-diyl (Irganox 1010).

[0083] In addition to the essential components as described above, the rubber composition according to the present invention may contain various components as described below (hereinafter, collectively and appropriately referred to simply as additional components).

[0084] [Softener] The rubber composition according to the present invention may contain a softener as an oil component other than silicone oil. For example, when the rubber component is 100 parts by mass, a preferred example is that the softener is contained in an amount of 20 to 100 parts by mass. The preferred example of the content of the softener is the amount including the softener (oil extended portion) impregnated in the ethylene-α-olefin-non-conjugated polyene copolymer.

[0085] As described above, the rubber composition according to the present invention has a Mooney viscosity (ML 1+4An example is an ethylene-α-olefin-non-conjugated polyene copolymer having a molecular weight (Mw) of 60 to 200, and when a softener is added to such a rubber composition (for example, in an amount of 20 to 100 parts by mass), a rubber composition having excellent kneading processability and molding processability is easily obtained. From the viewpoint of compatibility with the ethylene-α-olefin-non-conjugated polyene copolymer, it is preferable to use paraffin-based oil and / or ethylene-α-olefin copolymer-based hydrocarbon synthetic oil as the softener.

[0086] In addition, since the rubber composition according to the present invention contains an organic peroxide as a crosslinking agent, crosslinking inhibition may occur depending on the type of softener used, resulting in a decrease in heat resistance and deterioration of the compression set rate. In particular, when a softener with a low aniline point is used, crosslinking inhibition is likely to occur. For this reason, when a softener is contained in the rubber composition, it is more preferable to use a paraffin-based oil and / or an ethylene-α-olefin copolymer-based hydrocarbon-based synthetic oil with an aniline point of 120°C or higher. Furthermore, in consideration of heat resistance in a high-temperature atmosphere exceeding 150°C, it is better for the viscosity of the softener to be somewhat high. Specifically, it is more preferable for the kinetic viscosity at 100°C to be 20 CSt or higher.

[0087] [Carbon Black] The rubber composition according to the present invention may contain carbon black. Known carbon blacks can be used as the carbon black, and are not particularly limited. For example, carbon blacks having an iodine adsorption of 15 mg / g to 125 mg / g and a DBP absorption of 25 ml / 100 g to 190 ml / 100 g can be used. Considering the balance between vibration durability and low dynamic magnification, carbon blacks having an iodine adsorption of 20 to 30 (mg / g) and a DBP absorption of 100 to 150 (ml / 100 g) can be used, and a preferred example is carbon black containing 30 to 70 parts by mass.

[0088] [Filler] The rubber composition according to the present invention may contain a filler for the purpose of, for example, adjusting hardness and improving processability. As the filler, for example, silica such as wet silica, dry silica, colloidal silica, calcium carbonate, clay, talc, and other fillers used in ordinary rubber compositions can be applied. These fillers can be used alone or in combination of two or more. Among them, silica can be used preferably when a low dynamic magnification is desired, since it is expected to have a low dynamic magnification effect by using it in combination with the silane coupling agent described below and / or by using silica that has been previously treated with a silane coupling agent.

[0089] [Coupling Agent] The rubber composition according to the present invention may contain a coupling agent for carbon black and a silane coupling agent for coupling with silica, for example, for the purpose of lowering dynamic magnification and improving dispersibility. Examples of the coupling agent for carbon black include hydrazide compound coupling agents, sulfide compound coupling agents, and pyrazolone compound coupling agents, and examples of the silane coupling agent include mercapto silane coupling agents, sulfide silane coupling agents, amine silane coupling agents, epoxy silane coupling agents, and vinyl silane coupling agents. These can be used alone or in combination of two or more. Among them, preferred examples of the silane coupling agent include mercapto silane coupling agents and sulfide silane coupling agents.

[0090] [Vulcanization aid] The rubber composition according to the present invention preferably contains a vulcanization aid such as zinc oxide (ZnO) or composite zinc oxide, and further preferably contains a vulcanization aid such as stearic acid or zinc stearate in combination with zinc oxide (ZnO) or composite zinc oxide.

[0091] Here, composite zinc oxide is known to have a layer of zinc oxide (zinc oxide) on the surface and contain an inorganic metal salt inside as a core component, and specific examples include the META-Z L series (META-Z L40, L50, L60) manufactured by Inoue Lime Industry Co., Ltd.

[0092] A preferred example of the content of zinc oxide or zinc oxide composite is 3 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the rubber component. A preferred example of the content of stearic acid or zinc stearate is 0.1 parts by mass or more and 2 parts by mass or less per 100 parts by mass of the rubber component.

[0093] [Processing aids] The rubber composition according to the present invention may contain a processing aid, for example, for the purpose of improving processability. Compounds used in normal rubber processing can be used as the processing aid. For example, additives such as lubricants, tackifiers, dispersants, compatibilizers, and homogenizers can be used.

[0094] [Example of exhaust mount configuration] The exhaust mount made using the rubber composition according to the present invention may have a configuration capable of supporting an exhaust pipe in a suspended state relative to a vehicle body in a vibration-proof manner, and various embodiments can be mentioned. One example is a configuration in which an attachment hole into which a mounting pin on the vehicle body side is inserted (hereinafter simply referred to as a vehicle body-side attachment hole) and an attachment hole into which a mounting pin on the exhaust pipe side is inserted (hereinafter simply referred to as an exhaust pipe-side attachment hole) are provided, and the mount is interposed between the vehicle body and the exhaust pipe to support the exhaust pipe in a suspended state relative to the vehicle body in a vibration-proof manner.

[0095] The shapes, installation positions, numbers, etc. of the vehicle body side mounting hole and the exhaust pipe side mounting hole can be set appropriately according to the corresponding mounting pins (vehicle body side mounting pin, exhaust pipe side mounting pin). For example, when there is one mounting pin corresponding to each of the vehicle body side mounting hole and the exhaust pipe side mounting hole, at least one vehicle body side mounting hole and one exhaust pipe side mounting hole are formed, but it is also acceptable to form multiple of each.

[0096] In addition, there are no particular limitations on the shape of the stopper portion, which is formed assuming a large load is applied to the exhaust mount itself, or the shapes of the solid wall portions and hollow portions (hollow portions) of the exhaust mount.

[0097] The shape, installation position, number, etc. of the mounting pins are not particularly limited, and an example is one made of a hard material such as a roughly cylindrical metal. The mounting pins may be configured to be directly inserted into the corresponding mounting holes (vehicle body mounting hole, exhaust pipe mounting hole) (hereinafter simply referred to as a direct insertion configuration), or may be configured to be indirectly inserted via a metal collar (e.g., a metal collar inserted in advance into the mounting hole) (hereinafter simply referred to as an indirect insertion configuration). Whether a direct insertion configuration or an indirect insertion configuration is adopted, similar results will be obtained when evaluating (testing) the exhaust mount shown in the examples described below, for example.

[0098] [Method of preparing rubber composition] The rubber composition according to the present invention comprises an ethylene-α-olefin-non-conjugated polyene copolymer, 1.5 to 3.5 parts by mass of an organic peroxide, and a rubber composition having a kinematic viscosity of 20 mm at 25° C. 2 The essential components are 1 to 15 parts by mass of silicone oil (having a viscosity of 100 / s or more) and 2 to 8 parts by mass of a benzimidazole-based anti-aging agent, and the composition can be prepared by kneading these essential components (and additional components, if necessary) using a kneading machine such as a pressure kneader, a Banbury mixer, an intermix mixer, or an open roll.

[0099] [How to prepare the exhaust mount] The exhaust mount according to the present invention can be obtained as a rubber elastomer by crosslinking the rubber composition under the crosslinking conditions (crosslinking temperature and crosslinking time) that are appropriately set depending on the type of crosslinking agent used in the rubber composition and the molding machine (for example, at a crosslinking temperature of 150 to 190°C for 3 to 60 minutes).

[0100] The molding machine is not particularly limited, and various molding machines can be used as appropriate. For example, a compression molding method in which a rubber composition is charged (placed) in a predetermined position (cavity) of a mold and pressed under pressure, or a transfer molding machine or an injection machine is used to inject a rubber composition into a mold cavity and vulcanize it under pressure, etc., can be mentioned. Among them, a preferred example is the injection molding method, which has excellent productivity. EXAMPLES

[0101] Examples (Examples 1 to 22) according to this embodiment will be shown below, but the present invention is not limited to these examples.

[0102] 1 to 3 are diagrams illustrating a molded body 1, which is an example of an exhaust mount produced using a rubber composition according to the present invention. As shown in the figures, the molded body 1 is molded into an elliptical cylindrical shape (elliptical plate shape), and has a shape that is symmetrical (symmetrical about the center) in the major axis direction (the vertical direction in FIG. 2; hereinafter, simply referred to as the major axis direction of the molded body) and the minor axis direction (the horizontal direction in FIG. 2; hereinafter, simply referred to as the minor axis direction of the molded body), and also has a shape that is symmetrical (symmetrical about the center) in the thickness direction (the horizontal direction in FIG. 3).

[0103] A vehicle body side mounting hole 2A and an exhaust pipe side mounting hole 2B, each penetrating in the thickness direction, are formed at a distance from each other at both outer ends of the wall portion 10 in the major diameter direction of the molded body. In addition, a cutout portion 2C penetrating in the thickness direction is formed between the vehicle body side mounting hole 2A and the exhaust pipe side mounting hole 2B of the wall portion 10 (on the inner periphery side of the side wall portion 3).

[0104] In the case of the lightening portion 2C in the figure, the central portion of the lightening portion 2C in the short diameter direction of the molded body is shaped to be reduced in diameter on the inside in the long diameter direction of the molded body (reduced in diameter compared to both outer end portions of the lightening portion 2C in the short diameter direction of the molded body), and the radial cross section of the lightening portion 2C is substantially H-shaped. As a result, in the wall portion 10, stopper portions 4 are formed between the lightening portion 2C and the vehicle body side mounting hole 2A and the exhaust pipe side mounting hole 2B, each of which has a shape that protrudes inward in the long diameter direction of the molded body.

[0105] Specifically, in the molded body 1 produced using the rubber compositions of Examples 1 to 22 and Comparative Examples 1 to 10 described below, the dimension (H1) in the major axis direction of the molded body was 61 mm, the dimension (W1) in the minor axis direction of the molded body was 55 mm, and the dimension (L1) in the thickness direction was 30 mm. The dimension (H2) between the respective axes of the vehicle body side mounting hole 2A and the exhaust pipe side mounting hole 2B was 35 mm, and the dimension (W2) of the lightening portion 2C in the minor axis direction of the molded body was 39 mm.

[0106] Furthermore, the vehicle body side mounting hole 2A and the exhaust pipe side mounting hole 2B both have a circular cross-sectional shape with the same size (R1; 9.5 mm) in radial direction. The vehicle body side mounting hole 2A and the exhaust pipe side mounting hole 2B each have a tapered shape with the opening end gradually increasing in diameter toward the opening side.

[0107] <Preparation of rubber composition> The rubber compositions of Examples 1 to 22 and Comparative Examples 1 to 10 were prepared by blending and kneading various materials in the ratios shown in Tables 1 to 4. The kneading was carried out by first kneading materials other than the crosslinking system (crosslinking agent (vulcanizing agent), crosslinking assistant, and vulcanization accelerator) for 5 minutes using a Banbury mixer to obtain a kneaded product. Next, the crosslinking system was added to the kneaded product while cooling it using an open roll (cooling was performed by setting the cooling water temperature in the open roll to about 20°C), and kneading for 5 minutes to prepare each rubber composition.

[0108] In the preparation of the rubber composition of Comparative Example 6, when the kneaded product obtained by kneading in the Banbury mixer was discharged from the Banbury mixer as described above, the kneaded product was not well-formed, and further, when the discharged kneaded product was tried to be fed into an open roll, it slipped on the surface of each roll and could not enter the gap between each roll. Therefore, the rubber composition of Comparative Example 6 could not be prepared, and it was considered to be unprocessable, and the tests and evaluations shown in Tables 5 to 8 described later could not be performed (the overall judgment in Table 8 was "x").

[0109] [Table 1]

[0110] [Table 2]

[0111] [Table 3]

[0112] [Table 4]

[0113] The various materials listed in Tables 1 to 4 are as follows. Ethylene-α-olefin-non-conjugated polyene copolymer-1: "EPT3072EM" manufactured by Mitsui Chemicals, Inc. (40 parts by mass paraffin oil extended, Mooney viscosity (ML) at 125°C in the oil-extended state) 1+4 ) 51, ethylene content 64%, non-conjugated polyene = ENB content 5.4%, Mooney viscosity (ML) at 125 ° C in an unextended state 1+4 )120) Ethylene-α-olefin-non-conjugated polyene copolymer-2: Eneos Corporation "EP33": (Mooney viscosity at 125°C (ML 1+4 )28, ethylene content 52%, non-conjugated polyene (ENB) content 8.1%) Ethylene-α-olefin-non-conjugated polyene copolymer-3: Dow Inc. "NORDEL IP4770P" (Mooney viscosity at 125°C (ML 1+4 ) 70, ethylene content 70%, non-conjugated polyene = ENB content 4.9%) Ethylene-α-olefin-non-conjugated polyene copolymer-4: "PX006M" manufactured by Mitsui Chemicals, Inc. (Mooney viscosity at 125°C (ML 1+4 ) 69, ethylene content 60%, non-conjugated polyene (VNB content 1.5%) Zinc oxide: Sakai Chemical Industry Co., Ltd. "Zinc oxide type 2" Stearic acid: "Camellia stearate" manufactured by Nippon Oil & Fats Co., Ltd. Organic peroxide-1: Dicumyl peroxide (Dicumyl peroxide), NOF Corporation's "Percumyl D-40" (Dicumyl peroxide 40% powder product) Organic peroxide-2: 2,5-dimethyl-2,5-di(t-butylperoxy)-hexane, NOF Corp. "Perhexa 25B-40" Silicone oil-1: Dimethyl silicone oil, Shin-Etsu Chemical Co., Ltd. "KF96-50cs" (Kinematic viscosity (25 °C) 50 mm 2 / s) Silicone oil-2: Dimethyl silicone oil, Shin-Etsu Chemical Co., Ltd. "KF96-100cs" (dynamic viscosity (25 °C) 100 mm 2 / s) Silicone oil-3: Dimethyl silicone oil, Shin-Etsu Chemical Co., Ltd. "KF96-500cs" (Kinematic viscosity (25 °C) 500 mm 2 / s) Silicone oil-4: Dimethyl silicone oil, Shin-Etsu Chemical Co., Ltd. "KF96-5000cs" (dynamic viscosity (25 °C) 5000 mm 2 / s) Silicone oil-5: Dimethyl silicone oil, Shin-Etsu Chemical Co., Ltd. "KF96-10cs" (Kinematic viscosity (25 °C) 10 mm 2 / s) · Anti-aging agent - 1:2-mercaptobenzimidazole, "Nocrac MB" manufactured by Ouchi Koh Co., Ltd. · Anti-aging agent - 2:2-mercaptobenzimidazole zinc salt, "Nocrac MBZ" manufactured by Ouchi Koh Co., Ltd. · Anti-aging agent - 3: 2-mercaptomethylbenzimidazole, "Nocrac MMB" manufactured by Ouchi Koh Co., Ltd. Anti-aging agent-4: 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, "Nocrac CD" manufactured by Ouchi Kogyosha Anti-aging agent-5: Bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid][2,2-bis[[1-oxo-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propoxy]methyl]propane]-1,3-diyl, "Irganox 1010" manufactured by BASF Japan Ltd. Paraffin oil-1: Paraffin-based mineral oil, Idemitsu Kosan Co., Ltd. "Diana Process Oil PW-380" (aniline point 144.4℃, kinematic viscosity (100℃) 30mm 2 / s) Paraffin oil-2: Paraffin-based mineral oil, Idemitsu Kosan Co., Ltd. "Diana Process Oil PW-90" (aniline point 127.7℃, kinematic viscosity (100℃) 11mm 2 / s) Paraffin oil-3: Paraffin-based mineral oil: JX Nippon Oil & Energy Corporation "Process Oil P-300" (aniline point 106.3°C, kinematic viscosity (100°C) 7.7mm 2 / s) Liquid ethylene-α-olefin copolymer (synthetic oil)-1: "Lucant LX010" manufactured by Mitsui Chemicals, Inc. Liquid ethylene-α-olefin copolymer (synthetic oil)-2: "Lucant LX400" manufactured by Mitsui Chemicals, Inc. Vulcanization accelerator - 1:2-mercaptobenzothiazole, "Noccela MP" manufactured by Ouchi Kogyo Chemical Co., Ltd. Vulcanization accelerator-2: (N-cyclohexyl-2-benzothiazolylsulfenamide), "Noccela CZ-G" manufactured by Ouchi Kogyo Chemical Co., Ltd. Vulcanization accelerator-3: Tetramethylthiuram disulfide, "Noccela TT-P" manufactured by Ouchi Koh Co., Ltd. Vulcanization accelerator-4: Zinc dibutyldithiocarbamate, "Noccela BZ-P" manufactured by Ouchi Kogyo Chemical Co., Ltd. Vulcanization accelerator-4: Diethylthiourea, "Accel EUR" manufactured by Kawaguchi Chemical Co., Ltd. Sulfur: Sulfur, Tsurumi Chemical Industry Co., Ltd. "Kinka Brand Fine Sulfur 200MESH" Carbon black-1: Nitrogen adsorption specific surface area 22m 2 / g (SRF-HS grade), iodine adsorption 20-30 (mg / g) and DBP absorption 100-150 (ml / 100g) Asahi Carbon Co., Ltd. "Asahi #52" (iodine adsorption 22mg / g, DBP absorption 128ml / 100g) Carbon black-2: Nitrogen adsorption specific surface area 47m 2 / g (MAF grade), "Niteron #10" manufactured by Nippon Steel Carbon Co., Ltd. (iodine adsorption capacity 52 mg / g, DBP absorption capacity 126 ml / 100 g) Using the rubber compositions of Examples 1 to 22 and Comparative Examples 1 to 10 (excluding Comparative Example 6) shown in Tables 1 to 4, evaluation samples were prepared as described below.

[0114] <Creating evaluation samples (crosslinked rubber)> [Preparation of crosslinked rubber sheets for measuring type A durometer hardness, tensile properties, and properties after heat aging] For the rubber compositions of Examples 1 to 22 and Comparative Examples 1 to 10 (excluding Comparative Example 6) shown in Tables 1 to 4, vulcanization molding was performed by compression molding using a 2 mm sheet mold with a cavity of approximately 2 mm in thickness at 170°C for a vulcanization time of 12 minutes to obtain 2 mm thick vulcanized rubber sheets (hereinafter simply referred to as evaluation rubber sheets).

[0115] [Preparation of crosslinked rubber test pieces for compression set test] The rubber compositions of Examples 1 to 22 and Comparative Examples 1 to 10 (excluding Comparative Example 6) shown in Tables 1 to 4 were compression molded using a cylindrical test piece preparation mold having a diameter of 29.0 mm and a height of 12.5 mm at 170°C for a vulcanization time of 15 minutes to obtain cylindrical vulcanized rubber test pieces for compression set testing having a diameter of 29.0 mm and a height of 12.5 mm (hereinafter simply referred to as rubber test pieces).

[0116] <Test methods, evaluation methods and judgments> The test methods, evaluation methods and judgment methods for the rubber compositions (crosslinked rubbers) of Examples 1 to 22 and Comparative Examples 1 to 10 (excluding Comparative Example 6) shown in Tables 1 to 4 are as follows. The evaluation results and judgment results are also shown in Tables 5 to 8 below. The type A durometer hardness (HA) and tensile properties (EB, TB) under the heading "Initial crosslinked rubber material properties" shown in Tables 5 to 8 respectively indicate the physical properties before heat aging.

[0117] [Type A durometer hardness] For each evaluation rubber sheet obtained using the rubber composition of Examples 1 to 22 and Comparative Examples 1 to 10 (excluding Comparative Example 6), three sheets were prepared according to JIS K6253-3 (2012), and the flat parts were stacked to obtain a test piece (i.e., a test piece with a thickness of about 6 mm). Then, for each test piece, the hardness (HA) was measured using a type A durometer in accordance with JIS K6253-3 (2012). The hardness (HA) value was a value read 3 seconds after applying a pressure of 1 kgf to each test piece using a type A durometer.

[0118] [Tensile properties] For each evaluation rubber sheet obtained using the rubber composition of Examples 1 to 22 and Comparative Examples 1 to 10 (excluding Comparative Example 6), a JIS No. 3 dumbbell was used to punch out, and the elongation at break (EB) and tensile strength at break (TB) were measured in accordance with JIS K 6251. For the evaluation, a tensile strength at break (TB) of 20 MPa or more was judged as "◎", and a tensile strength at break (TB) of less than 20 MPa and 15 MPa or more was judged as "◯". In addition, when the tensile strength at break (TB) was less than 15 MPa and 10 MPa or more, it was deemed that it may be usable depending on the exhaust mount shape, and was judged as "◯△", and when the tensile strength at break (TB) was 10 MPa or less, it was deemed that it was likely to be insufficient in strength as a material for exhaust mounts and was unsuitable, and was judged as "×".

[0119] [Compression set rate] Each rubber test piece obtained using the rubber composition of Examples 1 to 22 and Comparative Examples 1 to 10 (excluding Comparative Example 6) was compressed by 25.0% in the height direction (height 9.38 mm) using a jig in accordance with JIS K6262 (2013), and left in a gear-type aging tester (forced circulation type heat aging tester) at an ambient temperature of 180°C for 24 hours and 72 hours, and then the rubber test piece was taken out together with the jig and quickly released. After this release, the rubber test piece was left on a wooden stand in an atmosphere of 23°C for 30 minutes, and the height (h1) of the rubber test piece was measured, and the compression set CS (%) was calculated.

[0120] The calculation method (formula) for compression set CS complies with JIS K6262 (2013) and is as shown in the following formula (1).

[0121] CS(%)=((h0-h1) / (h0-hs))×100 ……(1) In this formula (1), h0 is the thickness (mm) of the rubber test piece before compression, h1 is the thickness (mm) of the rubber test piece after it has been removed from the compression device, and hs is the thickness (mm) of the spacer used.

[0122] In Tables 5 to 8, the compression set rate (CS (%) (180°C x 24H) when compressed at an ambient temperature of 180°C for 24 hours is shown in the item "Compression set rate-1," and the compression set rate (CS (%) (180°C x 72H) when compressed at an ambient temperature of 180°C for 72 hours is shown in the item "Compression set rate-2."

[0123] The smaller the value of the compression set CS calculated by the formula (1), the smaller the compression set rate and the better the heat setting resistance. Therefore, in the evaluation, the compression set CS (%) was judged as "◎" when it was less than 30%, "◯" when it was 30% or more and less than 40%, and "×" when it was 40% or more.

[0124] [Heat aging resistance-1] For each of the rubber sheets obtained using the rubber compositions of Examples 1 to 22 and Comparative Examples 1 to 10, a JIS No. 3 dumbbell was first punched out, and a heat aging test was performed in accordance with JIS K 6257 by holding the sheets in a gear-type aging tester (forced circulation type heat aging tester) at an ambient temperature of 180°C or 190°C for various holding times (72 hours, 120 hours, 240 hours).

[0125] Next, the type A durometer hardness (HA) and tensile properties (EB, TB) after the heat aging test were measured in the same manner as in the above items [Type A durometer hardness] and [Tensile properties].

[0126] The rate of change AcKs (%) (the rate of change of the value after the heat aging test relative to the value before the heat aging test) was calculated from the difference between the static spring constant (Ks) before and after the heat aging test.

[0127] The calculation method (formula) for AcEB(%) and AcTB(%) conforms to JIS K6257 (2013) and is as shown in the following formula (2).

[0128] Ac = (x1-x0) / x0 × 100 …… (2) In this formula (2), Ac represents the rate of change (%) of the physical property after heat aging relative to the physical property before heat aging, x0 represents the median value of the physical property before heat aging, and x1 represents the median value of the physical property after heat aging.

[0129] In the heat aging test at an atmospheric temperature of 180°C for 72 hours and 120 hours, both AcEB(%) and AcTB(%) were judged as "good" when they were -30% or more, and among the "good" cases, AcEB(%) was judged as "good" when they were -60% or more when they were 240 hours long at an atmospheric temperature of 180°C. In addition, AcEB(%) and AcTB(%) were judged as "bad" when they were -30% or less when they were 72 hours long and 120 hours long at an atmospheric temperature of 180°C. Furthermore, in the heat aging test at an atmospheric temperature of 190°C for 72 hours, AcEB(%) was judged as "good" when they were -30% or more, AcEB(%) was judged as "good" when they were less than -30% and -50% or more, and AcEB(%) was judged as "bad" when they were less than -50%.

[0130] <Creating the exhaust mount molded body> The rubber compositions of Examples 1 to 22 and Comparative Examples 1 to 10 (excluding Comparative Example 6) were used to prepare the molded bodies 1 shown in Figs. 1 to 3. The mold used to prepare the molded body 1 was one that could obtain a rubber elastic body (molded body 1 to become an exhaust mount) having the shape shown in Figs. 1 to 3 when the rubber composition was injected into the mold cavity and crosslinked. The mold was then set in an injection molding machine, the mold temperature was set to 170°C ± 1°C, and the rubber composition was injection molded into the mold cavity by the injection molding machine (injection molded into a mold cavity at approximately 170°C). Thereafter, the mold was held for 10 minutes under the set conditions that maintained the mold temperature, and then demolded to prepare the molded body 1 having the shape shown in Figs. 1 to 3.

[0131] <Product (exhaust mount) testing> In the molded body 1 produced using the rubber compositions of Examples 1 to 22 and Comparative Examples 1 to 10 (excluding Comparative Example 6) as described above, first, a collar C made of S45C having a columnar body portion of Φ10 mm and a length in the axial direction (left and right direction in FIG. 5) of 35 mm was inserted into each of the vehicle body side mounting hole 2A and the exhaust pipe side mounting hole 2B as shown in Figures 4 and 5. Then, with iron pieces fixed to measuring jigs J at both ends of the axial direction of the collar C, the following tests of vibration characteristics (initial vibration characteristics) and durability in a high temperature atmosphere (vibration durability before and after heat aging) were carried out.

[0132] [Vibration characteristics; Static characteristics Ks] In accordance with JIS K 6385 (2012), a cycle (hereinafter simply referred to as a compression-expansion cycle) in which a step of compressing the molded body 1 inward in the long diameter direction of the molded body and a step of expanding (pulling) the molded body 1 outward in the long diameter direction of the molded body were sequentially performed three times using a measuring jig J attached to the molded body 1 (attached via a collar C) as shown in Figures 4 and 5.

[0133] The compression step was performed by compressing and displacing the molded body 1 inward in the long diameter direction of the molded body by 10 mm at a displacement speed of 10 mm / min from a state in which the molded body 1 was unloaded (load 0) in the long diameter direction of the molded body (hereinafter, displacement toward the compression side may be indicated as a negative value. For example, a compression of 10 mm is indicated as "-10 mm"). The expansion step was performed by expanding the molded body 1, which was in a compressed state in the compression step, by displacing it outward in the long diameter direction of the molded body by 25 mm from the compressed state at a displacement speed of 10 mm / min (hereinafter, displacement toward the expansion side may be indicated as a positive value. For example, a 25 mm expansion is indicated as "+25 mm").

[0134] Then, the load-deflection relationship in the third compression-expansion cycle was measured, and a load-deflection curve was created based on the results. From the load-deflection curve, the load F1 when the deflection was 0 and the load F2 when the deflection was 10 mm (in the expansion direction) were read, and the static spring constant Ks (N / mm) was calculated by appropriately substituting the loads F1 and F2 into the relational equation "Ks = (F2-F1) / (10-0)".

[0135] [Vibration characteristics; dynamic characteristics Kd100 and dynamic magnification] As shown in Figures 4 and 5, a tensile load of 50N was applied to the molded body 1 toward the outside in the long diameter direction of the molded body through a measuring jig J attached to the molded body 1 (attached through a collar C), thereby expanding the molded body 1. Then, a test was performed in which a constant displacement harmonic compression vibration of amplitude ±0.4mm was applied at a frequency of 100Hz to the molded body 1 in the expanded state, and the dynamic spring constant Kd100 (N / mm) at 100Hz was obtained in accordance with the "non-resonance method (a)" in the "Test method for vibration-proof rubber" of JIS-K-6385-2012. Then, the dynamic magnification (=Kd100 / Ks) was calculated from the obtained dynamic spring constant (Kd100) and the calculated static spring constant (Ks).

[0136] As mentioned above, from the viewpoint of vibration-proofing characteristics, the smaller the dynamic magnification, the better. Also, from the viewpoint of exhaust mounting, the spring constant is also a large shape factor, and it is not possible to determine an upper limit in general. Therefore, in the evaluation, a dynamic magnification ratio (=Kd100 / Ks) of less than 2.5 was judged as "Good", and a dynamic magnification ratio of 2.5 or more and less than 3.5 was judged as "Good or △". Note that within the scope of Examples 1 to 22 and Comparative Examples 1 to 10, there was no product with a dynamic magnification ratio (=Kd100 / Ks) of 3.5 or more.

[0137] [Vibration durability in high temperature environments] The molded body 1 in the state shown in Figures 4 and 5 was placed in various temperature atmospheres (150°C, 180°C, 200°C) and subjected to repeated vibration (10 Hz) in a compression-expansion cycle to perform a vibration durability test. In the repeated vibration, the displacement on the compression side was 7 mm (-7 mm) and the displacement on the expansion side was 23 mm (+23 mm).

[0138] In this way, the vibration load changes rapidly when the molded body 1 is repeatedly vibrated and breaks or a large crack (harmful crack) occurs in the molded body 1. Therefore, in the repeated vibration, the maximum load on the compression side (the largest load on the negative side) and the maximum load on the expansion side (the largest load on the positive side) from the start of vibration to the 1000th vibration were read, and the number of repeated vibrations at which each maximum load value changed by 20% or more was determined as the durability number of the molded body 1.

[0139] In the case of repeated vibration (vibration durability test) in 150℃ and 180℃ atmospheres, it was continued up to 4 million times as long as there was no change of 20% or more in the vibration load, and in the case of repeated vibration in 200℃ atmosphere, it was continued up to 3 million times as long as there was no change of 20% or more in the vibration load. In the case of repeated vibration in 150℃ and 180℃ atmospheres, the case where there was no change of 20% or more in the vibration load even after 4 million times of repeated vibration was defined as "OK for 4 million times." In the case of repeated vibration in 200℃ atmosphere, the case where there was no change of 20% or more in the vibration load even after 3 million times of repeated vibration was defined as "OK for 3 million times."

[0140] Five molded bodies 1 were prepared for each of the rubber compositions of Examples 1 to 22 and Comparative Examples 1 to 10 (excluding Comparative Example 6), and vibration durability tests were conducted on all five of the molded bodies 1. For this reason, the evaluation was judged as "◎" when all five molded bodies 1 could be defined as "OK for 4 million cycles" (no abnormalities at 4 million cycles) in an atmosphere of 150°C and 180°C, and all five molded bodies 1 could be defined as "OK for 3 million cycles."

[0141] In addition, when one or more of the five molded bodies 1 could not be defined as "OK for 3 million cycles" but all of the five molded bodies 1 could be defined as "OK for 4 million cycles" in an atmosphere of 150°C and 180°C, it was judged as "Good." And, anything other than "Excellent" and "Good" was deemed to have not achieved durability and was judged as "Poor."

[0142] In Tables 5 to 8, the number n that could be defined as "OK for 3 million cycles" and the number n that could be defined as "OK for 4 million cycles" in the vibration endurance test of five molded bodies are each described as "n / 5." For example, if all five molded bodies could be defined as "OK for 3 million cycles" (or "OK ​​for 4 million cycles"), it is described as "5 / 5," and if only three could be defined as "OK for 3 million cycles" it is described as "3 / 5."

[0143] <Vibration durability in high temperature environments after thermal aging> First, the molded body 1 in the state shown in Figures 1 to 3 was subjected to heat aging by being held in a gear aging tester (forced circulation type heat aging tester) at various atmospheric temperatures (150°C, 180°C, 200°C) for 72 hours.

[0144] The molded bodies 1 in which the atmospheric temperatures for the thermal aging were 150°C and 180°C were placed in an atmosphere at 180°C in the state shown in Figures 4 and 5, and a vibration durability test was performed by repeatedly applying vibration (at 10 Hz) in a compression-expansion cycle similar to that in the above item [Vibration durability in a high-temperature atmosphere]. In the repeated vibration, the displacement on the compression side was 5 mm (-5 mm), and the displacement on the expansion side was 20 mm (+20 mm).

[0145] For the molded body 1 in which the atmospheric temperature for the thermal aging was 200°C, a vibration durability test was performed by placing it in an atmosphere of 180°C in the state shown in Figures 4 and 5 and repeatedly applying vibration (at 10 Hz) in a compression-expansion cycle similar to that in the item [Vibration durability in a high-temperature atmosphere] above. In the repeated vibration, the displacement on the compression side was 2 mm (-2 mm) and the displacement on the expansion side was 15 mm (+15 mm).

[0146] Then, when each of the molded bodies 1 was repeatedly vibrated, similarly to the above item [Vibration durability under high temperature atmosphere], the maximum load on the compression side (the largest load on the negative side) and the maximum load on the expansion side (the largest load on the positive side) from the start of vibration to the 1000th vibration were read, and the number of repeated vibrations at which each maximum load value changed by 20% or more was defined as the number of durability cycles of the molded body 1. In addition, the case where no significant change occurred in the vibration load even after repeated vibration up to 3 million times was defined as "OK for 3 million times".

[0147] As in the above item [Vibration durability under high temperature atmosphere], five molded bodies 1 were prepared for each of the rubber compositions of Examples 1 to 22 and Comparative Examples 1 to 10 (excluding Comparative Example 6), and a vibration durability test was conducted for all five molded bodies 1. For this reason, the evaluation was judged to be "◎" when all five molded bodies 1 could be defined as "OK for 3 million cycles" (no abnormalities after 3 million cycles).

[0148] Here, for the molded body 1 in which the atmospheric temperature for the heat aging was 200°C, even if one or more of the five molded bodies 1 could not be defined as "OK for 3 million cycles", it was deemed to have sufficient heat resistance up to 180°C and was judged as "◯". On the other hand, for the molded body 1 in which the atmospheric temperature for the heat aging was 150°C or 180°C, if even one of the five molded bodies 1 could not be defined as "OK for 3 million cycles", the vibration durability after heat aging of even one of the five molded bodies was deemed to have not achieved durability and was judged as "X".

[0149] <Overall Judgment> If all of the above-mentioned items were judged as "Good" or "Excellent", the overall judgment was judged as "Good". If there was no "X" in any of the items and any of the items were judged as "Good or △", the overall judgment was judged as "Good or △". If there was even one "X" in any of the items, the overall judgment was judged as "X".

[0150] [Table 5]

[0151] [Table 6]

[0152] [Table 7]

[0153] [Table 8]

[0154] <<Verification Results by Comparison of Examples 1 to 22 and Comparative Examples 1 to 10>> From the mixing ratios of various materials shown in Tables 1 to 4 and the results shown in Tables 5 to 8, the following can be seen.

[0155] First, in each of the rubber compositions of Examples 1 to 22, when the total rubber component is taken as 100 parts by mass, the rubber composition contains at least an ethylene-α-olefin-non-conjugated polyene copolymer in a range of 90 to 100 parts by mass, an organic peroxide in a range of 1.5 to 4.5 parts by mass, and has a kinematic viscosity of 20 mm at 25°C. 2 The composition contains 1 to 15 parts by mass of silicone oil having a molecular weight of 100 or more and 2 to 8 parts by mass of a benzimidazole-based antioxidant (hereinafter simply referred to as the composition of Examples 1 to 22).

[0156] Furthermore, according to the configurations of Examples 1 to 22, there is no need to worry about the initial physical properties and initial vibration characteristics (good or good / △) compared to at least Comparative Examples 1 to 10, and it is found that the permanent compression set rate (heat setting resistance), heat aging characteristics, vibration durability in a high-temperature atmosphere, and vibration durability in a high-temperature atmosphere after heat aging are extremely excellent.

[0157] In other words, an exhaust mount made of a cross-linked body (rubber elastomer) of the rubber composition of the present invention has excellent heat resistance, durability in high-temperature environments, and resistance to heat settling, and therefore can be suitably used, for example, as an exhaust mount in vehicles such as automobiles that are required to withstand severe thermal environments and to block vibrations from the exhaust pipe. [Explanation of symbols]

[0158] 1... Molded body (exhaust mount), 10... Wall portion 2A…Vehicle body side mounting hole 2B…Exhaust pipe side mounting hole 2C…Lightweight section (lightweight hole) 21A, 21B…hole wall part 3…Side wall 4...Stopper part C…Color J…Measuring tool

Claims

1. A rubber composition comprising an ethylene-α-olefin-non-conjugated polyene copolymer as a main rubber component, the rubber composition comprising 90 to 100 parts by mass of the ethylene-α-olefin-non-conjugated polyene copolymer, 1.5 to 4.5 parts by mass of an organic peroxide, and a kinematic viscosity at 25° C. of 20 mm ２ 2. A rubber composition for exhaust mounts, comprising 1 to 15 parts by mass of a silicone oil having a viscosity of 100 / s or more and 2 to 8 parts by mass of a benzimidazole-based antioxidant.

2. The kinetic viscosity (25°C) of the silicone oil is 40 to 600 mm ２ 2. The rubber composition for exhaust mounts according to claim 1, wherein the molar ratio of the rubber composition for exhaust mounts is 1:1 or 2:

1.

3. 2. The rubber composition for exhaust mounts according to claim 1, wherein said organic peroxide is dicumyl peroxide.

4. The rubber composition contains, as a softener, 20 to 100 parts by mass of an oil component other than silicone oil, based on 100 parts by mass of the total rubber component; the oil component is a paraffin-based oil and / or an ethylene-α-olefin copolymer-based synthetic hydrocarbon oil, 4. A rubber composition for exhaust mounts according to claim 1, wherein the oil component has an aniline point of 120° C. or higher.

5. The ethylene / α-olefin / non-conjugated polyene copolymer has an ethylene content of 63 to 75% by mass and a Mooney viscosity (ML) at 125° C. without oil extension. １＋４ 2. The rubber composition for exhaust mounts according to claim 1, wherein the molar ratio of the rubber composition to the total molar ratio of the exhaust mount is 60 to 200.

6. The rubber composition for exhaust mounts according to claim 1 or 5, characterized in that it contains 30 to 70 parts by mass of carbon black having an iodine adsorption amount of 20 to 30 (mg / g) and a DBP absorption amount of 100 to 150 (ml / 100g) relative to 100 parts by mass of the total rubber component.

7. an exhaust mount made of a rubber elastic body that is provided with mounting holes into which a mounting pin on a vehicle body side and a mounting pin on an exhaust pipe side are inserted, and that is interposed between the vehicle body and the exhaust pipe to provide vibration-proof support for the exhaust pipe in a suspended state relative to the vehicle body, The rubber elastic body is formed by crosslinking the rubber composition for exhaust mounts according to any one of claims 1 to 3 and 5.

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