JP2013018803A - Vibration-proof rubber composition and vibration-proof rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration-proof rubber excellent in a dynamic-to-static modulus ratio and compression set properties, and in particular, suitably usable in a high temperature environment such as an engine room of an automobile.SOLUTION: The vibration-proof rubber composition includes, as a rubber component: a natural rubber (NR); an ethylene-propylene-diene rubber (EPDM); and a terminal-modified butadiene rubber (terminal-modified BR) at a mass ratio (NR)/(EPDM)/(terminal-modified BR) of 45-65/30-45/5-20, and contains a peroxide as a vulcanizing agent and a zinc acrylate and/or a zinc methacrylate as a co-crosslinking agent.

Description

  The present invention relates to an anti-vibration rubber composition that can be suitably used in a high-temperature environment and an anti-vibration rubber obtained by curing the composition. In particular, the present invention relates to an anti-vibration rubber composition and an anti-vibration rubber that can be suitably used at high temperature sites such as automobile torsional dampers, engine mounts, and muffler hangers.

  Conventionally, in various vehicles such as automobiles, in order to improve the comfort of passengers, various anti-vibration materials have been arranged at sites that are sources of vibration and noise to reduce the intrusion of vibration and noise into the room. Attempts have been made. For example, for engines that are the main source of vibration and noise, vibrations during engine drive are absorbed by using anti-vibration rubber for components such as torsional dampers, engine mounts, and muffler hangers. Reduces the intrusion of vibration and noise and the spread of noise to the surrounding environment.

  As a basic characteristic of such an anti-vibration rubber, a strength characteristic that supports a heavy object such as an engine and an anti-vibration performance that absorbs and suppresses the vibration are required. Furthermore, when used in a high temperature environment such as an engine room, it has excellent strength characteristics, low dynamic magnification and excellent vibration proof performance, as well as heat resistance, ozone resistance and compression set characteristics. High is required. In particular, in recent years, the temperature in the engine room has been rising due to higher engine output and space saving in the engine room due to expansion of the indoor space, etc. It has become tough.

  Until now, natural rubber (NR), which has excellent physical properties such as fracture characteristics, has been often used as the rubber component of the vibration-proof rubber. However, although NR is excellent in destructive properties and the like, heat resistance and ozone resistance are inferior to synthetic rubber.

  Under such circumstances, in order to improve the heat resistance and ozone resistance characteristics of the anti-vibration rubber, part or all of the NR is replaced with ethylene / propylene / diene rubber (EPDM) and peroxide crosslinking is performed. ing. For example, JP-A-4-246448 (Patent Document 1) discloses a technique for improving heat resistance by adding unsaturated fatty acid zinc to EPDM alone, and JP-A-7-268147 (Patent Document 2). ) And JP-A-7-268148 (Patent Document 3) propose a heat- and vibration-proof rubber composition in which heat-resistant vibration-proof rubber having improved durability can be obtained by subjecting specific EPDM to peroxide crosslinking. ing. However, with these methods, there is a risk that the rubber properties such as tensile strength (room temperature, high temperature) and tearing properties and durability will be significantly reduced. Furthermore, the dynamic magnification, which is an important characteristic of the vibration-proof rubber, is increased, and the obtained cured product is often inferior in performance.

  On the other hand, as a vibration-proof rubber whose performance has been improved by other methods, a rubber molded product with high hardness and low dynamic ratio, which is based on a specific chloroprene-based rubber and contains a specific amount of carbon black and a softening agent. Heat-resistant and dynamic vulcanized with a peroxide using a rubber composition (Japanese Patent Laid-Open No. 8-127673: Patent Document 4) and an ethylene-α-olefin copolymer rubber containing no conjugated diene Anti-vibration rubber (Japanese Patent Laid-Open No. 1-299806: Patent Document 5) having excellent sag properties has been proposed, but further improvement is desired. In addition, in order to obtain an anti-vibration rubber composition capable of obtaining excellent anti-vibration performance, a technique using only a specific bismaleimide compound as a vulcanizing agent in a diene rubber (Japanese Patent Application Laid-Open No. 2006-273394: Patent Document) 6) has also been proposed, but it is also desirable to further improve the various properties of the anti-vibration rubber.

  In addition, the applicant of the present invention has previously worked by using zinc (meth) acrylate and a bismaleimide compound in combination with an NR / EPDM rubber compound without deteriorating the fracture characteristics, fatigue characteristics, and heat resistance of the rubber. A proposal has been made to lower the magnification and increase the compression set characteristics (Japanese Patent Application No. 2009-195021). However, even in this proposal, there was a slight decrease in the tensile properties of the vibration-proof rubber, and there was room for further improvement in dynamic magnification and compression set characteristics.

  Accordingly, it has been desired to develop an anti-vibration rubber excellent in all aspects of dynamic magnification, compression set characteristics and tensile physical properties (elongation, strength) while maintaining heat resistance.

JP-A-4-246448 JP 7-268147 A JP 7-268148 A JP-A-8-127673 Japanese Patent Laid-Open No. 1-299806 JP 2006-273941 A

  The present invention has been made in view of the above circumstances, and provides an anti-vibration rubber composition from which a rubber cured product excellent in dynamic magnification and compression set characteristics can be obtained, and an anti-vibration rubber obtained by curing the rubber composition. For the purpose.

  As a result of intensive studies to achieve the above object, the present inventor has obtained a part of a rubber component employing natural rubber (NR) and ethylene / propylene / diene rubber (EPDM) as a terminal modified butadiene rubber (terminal modified). BR), and the blending amount is adjusted to a ratio of (NR) / (EPDM) / (terminal-modified BR) = 45 to 65/30 to 45/5 to 20 by mass ratio, and excessively added as a vulcanizing agent. It was discovered that an anti-vibration rubber composition containing an oxide and containing zinc acrylate and / or zinc methacrylate as a co-crosslinking agent is excellent in both dynamic magnification and compression set characteristics. The present invention has been made.

  In other words, the present invention focuses on the base rubber / polymer system rather than the cross-linking system, and aims to improve the compression set characteristic, which is a problem to be solved, and to further improve the dynamic magnification. Specifically, in rubber compounding for anti-vibration rubber, when a part of NR of the main polymer in which NR and EPDM are blended at a specific ratio is replaced with butadiene rubber (BR) whose terminal is modified, heat resistance While maintaining the above, both the dynamic magnification and compression set characteristics can be improved at the same time. Moreover, NR and EPDM generally do not perform peroxide crosslinking, but in the present invention, by using peroxide together with zinc acrylate and / or zinc methacrylate, the main polymer of the base rubber Are co-crosslinked to sufficiently exhibit the above desired effect.

Accordingly, the present invention provides the following anti-vibration rubber composition and anti-vibration rubber.
[1] Natural rubber (NR), ethylene / propylene / diene rubber (EPDM) and terminal-modified butadiene rubber (terminal-modified BR) as a rubber component in terms of mass ratio (NR) / (EPDM) / (terminal-modified BR) = It is contained in a ratio of 45 to 65/30 to 45/5 to 20, contains a peroxide as a vulcanizing agent, and contains zinc acrylate and / or zinc methacrylate as a co-crosslinking agent. Rubber composition.
[2] A vibration-proof rubber obtained by curing the rubber composition according to the above [1].

  The anti-vibration rubber composition of the present invention improves both dynamic magnification and compression set characteristics while maintaining tensile properties and heat resistance, and is particularly useful in a high-temperature environment such as an engine room of an automobile. Anti-vibration rubber can be obtained.

  The anti-vibration rubber composition of the present invention is a ternary rubber compound using a combination of natural rubber (NR), ethylene / propylene / diene rubber (EPDM) and terminal-modified butadiene rubber (terminal-modified BR) as rubber components. Then, a peroxide as a vulcanizing agent and zinc acrylate and / or zinc methacrylate as a co-crosslinking agent are blended with the base rubber.

  About the compounding quantity of each rubber component, it is preferable to set it as the range of the ratio of (NR) / (EPDM) / (terminal modification BR) of the ratio of 45-65 / 30-45 / 5-20 by mass ratio. If the ratio of NR is too smaller than the above range, the strength characteristics may be lowered. Conversely, if it is too much, the heat resistance may be lowered. On the other hand, if the EPDM ratio is less than the above range, the heat resistance may be reduced, while if too high, the dynamic magnification may be deteriorated, and the durability and strength may be reduced.

  The above NR and EPDM may be appropriately selected from known ones and are not particularly limited.

  In the present invention, a predetermined amount of terminal-modified butadiene rubber is blended into the rubber composition, thereby improving the dynamic magnification and creep resistance at the same time. The terminal-modified butadiene rubber is not particularly limited as long as it is a butadiene rubber having a terminal modified.

  As the terminal modification method of the butadiene rubber, for example, a method of modifying the terminal (active terminal) of the butadiene rubber using a modifier can be used. Examples of such modifiers include tin halides such as tin tetrachloride and tin tetrabromide, halogenated organotin compounds such as tributyltin chloride, silicon compounds such as silicon tetrachloride and chlorotriethylsilane, and phenyl isocyanate. Examples include isocyanate group-containing compounds, amide compounds, lactam compounds, urea compounds, and isocyanuric acid derivatives.

  The cis content and the trans content of the terminal-modified butadiene rubber are not particularly limited, and a low cis butadiene rubber having a cis content of 35% or less, a high cis butadiene rubber having a cis content of 95% or more, and the like can be used. The terminal-modified butadiene rubber (BR) can be used alone, or two or more kinds of different terminal-modified butadiene rubbers can be mixed and used. Furthermore, terminal-modified butadiene rubber and general polybutadiene rubber can be used in combination. As for the blending amount of the terminal-modified butadiene rubber (the total amount in the case of two or more types), BR is 5 to 20 parts by mass as described above with respect to 100 parts by mass of the total amount of rubber components. If the blending amount of BR is less than the above range, improvement in creep resistance, dynamic magnification, etc. may not be seen. If the blending amount of BR is more than the above range, tensile properties, There is a risk that durability will deteriorate.

  As a specific trade name of the terminal-modified butadiene rubber, a trade name “Nippol BR1250H” manufactured by Nippon Zeon Co., Ltd. may be mentioned.

  In the present invention, the rubber component containing NR and EPDM is used as described above. However, as long as it does not deviate from the purpose, other rubber such as a known synthetic rubber is used in addition to the rubber component as necessary. May be used in combination. Specific examples include butadiene rubber, styrene / butadiene rubber, isoprene rubber, chloroprene rubber, isobutylene / isoprene rubber, acrylonitrile / polybutadiene rubber, silicone rubber, acrylic rubber, epoxidized natural rubber, acrylate polybutadiene rubber, and the like. Examples include synthetic rubbers or natural rubbers whose molecular chain ends are modified, and one or more of them may be appropriately selected and used. When blending the rubber, it is preferably 20% by mass or less (0 to 20% by mass) based on the total amount of the rubber components.

  As the vulcanizing agent, a peroxide is used in the present invention. In the present invention, by peroxide-crosslinking the rubber component using a peroxide as a vulcanizing agent, heat resistance and compression set characteristics are excellent as compared with the case of crosslinking using sulfur. As the peroxide, those normally used in this field can be blended, and specific examples thereof include dicumyl peroxide, benzoyl peroxide, 1,1-bis (t-butylperoxy) -3, 5,5-trimethylcyclohexane, diisobutyryl peroxide, cumylperoxyneodecanoate, di-n-propylperoxydicarbonate, diisopropylperoxydicarbonate, di-sec-butylperoxydicarbonate, 1,1, 3,3-tetramethylbutylperoxyneodecanoate, di (4-t-butylcyclohexyl) peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, t-hexylperoxyneodecanoate, t-butyl peroxyneodecanoate, t-butyl peroxy Oxyneoheptanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, di (3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, 1,1,3,3- Tetramethylbutylperoxy-2-ethylhexanoate, disuccinic acid peroxide, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, t-hexylperoxy-2-ethylhexa Noate, di (4-methylbenzoyl) peroxide, t-butylperoxy-2-ethylhexanoate, di (3-methylbenzoyl) peroxide, benzoyl (3-methylbenzoyl) peroxide, dibenzoyl peroxide 1,1-di (t-butylperoxy) -2-methylcyclohex 1,1-di (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (t-hexylperoxy) cyclohexane, 1,1-di (t-butylperoxy) Cyclohexane, 2,2-di (4,4-di- (t-butylperoxy) cyclohexyl) propane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy- 3,5,5-trimethylhexanoate, t-butyl peroxylaurate, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy 2-ethylhexyl monocarbonate, t-hexyl peroxybenzoate, 2,5- Di-methyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyacetate 2,2-di- (t-butylperoxy) butane, t-butylperoxybenzoate, n-butyl 4,4-di- (t-butylperoxy) valerate, di (2-t-butylperoxy) Oxyisopropyl) benzene, di-t-hexyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butylcumyl peroxide, di-t-butyl peroxide, p- Menthane hydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydro Peroxide, t-butyl hydroperoxide and the like. In the present invention, di (2-t-butylperoxy) is used. An isopropyl) benzene, can be suitably used dicumyl peroxide. These can be used individually by 1 type or in mixture of 2 or more types. The compounding amount of these vulcanizing agents is usually 1 to 10 parts by mass, preferably 2 to 8 parts by mass with respect to 100 parts by mass of the rubber component. When the blending amount exceeds 10 parts by mass, the rubber is excessively cured, which may cause a decrease in elongation at break and a decrease in durability. When the amount is less than 1 part by mass, the crosslinking density decreases and the breaking strength decreases. There is a risk of lowering, deterioration of dynamic magnification, deterioration of compression set, deterioration of durability, and the like.

  In addition, in the range which does not deviate from the objective of this invention, sulfur can also be mix | blended as a crosslinking adjuvant. When mix | blending this crosslinking adjuvant, it is preferable to make the compounding quantity into the range of 0.1-0.5 mass part with respect to 100 mass parts of rubber components.

  A co-crosslinking agent is an additive that causes a crosslinking reaction in rubber. In the present invention, zinc acrylate and / or zinc methacrylate is used as a co-crosslinking agent, and by using this together with the above peroxide, the main polymer of the base rubber is co-crosslinked, and the dynamic magnification and compression set are set. The above-mentioned desired effects such as characteristics are sufficiently exhibited.

  As the co-crosslinking agent, only one kind of zinc acrylate or zinc methacrylate may be used alone, or two or more kinds thereof may be used in combination. Moreover, a mixture of zinc acrylate and zinc methacrylate can also be used. The blending amount of the zinc acrylate and / or zinc methacrylate (hereinafter referred to as “zinc (meth) acrylate” for convenience) is not particularly limited, but is preferably 2 with respect to 100 parts by mass of the rubber component. The upper limit is preferably 6 parts by mass or less, more preferably 5 parts by mass or less. If the blending amount exceeds the above range, the rubber may be cured too much, leading to a decrease in elongation at break, and if the blending amount is less than the above range, the rubber is not sufficiently crosslinked, resulting in a decrease in breaking strength and a dynamic ratio. There is a risk that the deterioration of the compression set and the compression set characteristics may be deteriorated.

  In the present invention, the fatty acid ester can be blended with the rubber component together with the zinc (meth) acrylate, thereby improving the dispersibility of the zinc (meth) acrylate with respect to the rubber component during kneading. The mechanical properties of the rubber after vulcanization can be improved. Here, the fatty acid and alcohol constituting the fatty acid ester may both have a linear structure or a branched structure, may be either saturated or unsaturated, and the number of carbon atoms is not particularly limited. . In the present invention, a known fatty acid ester composed of a fatty acid having a chain length of 1 to 30 carbon atoms and an alcohol having a chain length of 1 to 30 carbon atoms can be used. May be ethyl stearate, propyl stearate, butyl stearate, ethyl palmitate, propyl palmitate, butyl palmitate and the like. These can be used alone or in combination of two or more. The amount of the fatty acid ester is preferably 0.02 to 1.2 parts by mass, more preferably 0.2 to 0.6 parts by mass with respect to 100 parts by mass of the rubber component. If the blending amount exceeds 1.2 parts by mass, the rubber may be softened, the workability may be deteriorated, and the dynamic magnification may be deteriorated. If the blending amount is less than 0.02 parts by mass, the dispersibility improvement effect may not be obtained. is there.

  Although this fatty acid ester exhibits an effect of improving dispersibility even when blended separately with the above-mentioned zinc (meth) acrylate at the time of kneading with the rubber component, the (meth) acrylic acid is previously obtained before kneading with the rubber component. By premixing with zinc, the dispersibility of zinc (meth) acrylate in the rubber component can be further improved.

  Moreover, with respect to the rubber component, an anti-aging agent, a wax, an antioxidant, a filler, a foaming agent, and a plasticizer that are usually used in the rubber industry as necessary within the range not impairing the effects of the present invention. , Oils, lubricants, tackifiers, petroleum resins, ultraviolet absorbers, dispersants, compatibilizing agents, homogenizing agents, and the like can be appropriately blended.

  As the oil, known oils can be used, and are not particularly limited. Specifically, process oils such as aromatic oils, naphthenic oils, paraffin oils, vegetable oils such as palm oil, alkylbenzene oils, etc. Synthetic oil, castor oil, etc. can be used. In the present invention, paraffin oil can be preferably used. These can be used alone or in combination of two or more. The blending amount of these oils is not particularly limited, but can be approximately 15 to 45 parts by mass with respect to 100 parts by mass of the rubber component. If the blending amount deviates from the above range, the kneading workability may be deteriorated. When oil-extended rubber is used for the rubber component, the total amount of oil contained in the rubber and oil added separately during mixing may be adjusted within the above range.

  It is recommended to mix carbon black as a reinforcing agent. Carbon black imparts various reinforcing functions to rubber depending on the types such as average particle diameter, structure and surface properties. As this carbon black, known ones can be used, and are not particularly limited, and examples thereof include carbon blacks such as SRF, GPF, FEF, HAF, ISAF, SAF, FT, MT, In the present invention, FEF can be preferably used. Moreover, these carbon blacks may be used individually by 1 type, and may use 2 or more types together. The blending amount of these carbon blacks is usually 15 to 60 parts by mass, preferably 20 to 50 parts by mass with respect to 100 parts by mass of the rubber component. When the amount exceeds 60 parts by mass, workability may be deteriorated, and when it is less than 15 parts by mass, adhesion may be deteriorated.

  In the present invention, from the viewpoint of promoting vulcanization, a vulcanization acceleration aid such as zinc white (ZnO) or a fatty acid can be blended. The fatty acid may be saturated, unsaturated, linear or branched fatty acid, and is not particularly limited as the carbon number of the fatty acid. For example, the fatty acid has 1 to 30 carbon atoms, preferably 15 to 15 carbon atoms. 30 fatty acids, more specifically naphthenic acid such as cyclohexane acid (cyclohexanecarboxylic acid), alkylcyclopentane having a side chain, hexanoic acid, octanoic acid, decanoic acid (including branched carboxylic acid such as neodecanoic acid), Saturated fatty acids such as dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid (stearic acid), unsaturated fatty acids such as methacrylic acid, oleic acid, linoleic acid, linolenic acid, resin acids such as rosin, tall oil acid, abietic acid, etc. Is mentioned. These may be used alone or in combination of two or more. In the present invention, zinc white and stearic acid can be preferably used. The compounding amount of these vulcanization acceleration aids is preferably 1 to 10 parts by mass, more preferably 2 to 7 parts by mass with respect to 100 parts by mass of the rubber component. If the blending amount exceeds 10 parts by mass, workability and dynamic magnification may be degraded, and if it is less than 1 part by mass, vulcanization delay may occur.

  As the anti-aging agent, known ones can be used, and are not particularly limited, and examples thereof include a phenol type anti-aging agent, an imidazole type anti-aging agent and an amine type anti-aging agent. The blending amount of these anti-aging agents is usually 2 to 10 parts by mass, preferably 3 to 7 parts by mass with respect to 100 parts by mass of the rubber component.

  When obtaining the rubber composition of the present invention, there is no particular limitation on the blending method of each of the above components, and all the component raw materials may be blended and kneaded at once, and each component may be divided into two or three stages. You may mix | blend and knead | mix. At that time, by premixing with the fatty acid ester before kneading the (meth) zinc acrylate with the rubber component, the dispersibility of the (meth) zinc acrylate in the rubber component is further improved, and the resulting rubber The mechanical properties can be further improved. In the kneading, a kneader such as a roll, an internal mixer, a Banbury rotor or the like can be used. Furthermore, when forming into a sheet shape or a belt shape, a known molding machine such as an extrusion molding machine or a press machine may be used.

  Moreover, there are no particular limitations on the vulcanization conditions for curing the rubber composition, but vulcanization conditions can be generally employed at 140 to 180 ° C. for 5 to 120 minutes.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not restrict | limited to the following Example.

[Examples 1-6, Comparative Examples 1-9]
It knead | mixes and vulcanizes with the compounding composition shown in the following Table 1, each of the anti-vibration rubber compositions of Examples 1 to 6 and Comparative Examples 1 to 9 is vulcanized and cured under predetermined conditions, and is 120 mm long × 120 mm wide X A sheet molded product having a thickness of 2 mm was prepared. This sheet was used as an evaluation body of the vibration-proof rubber of the present invention. The obtained rubber sheet was measured and evaluated for compression set, static spring constant (Ks), dynamic spring constant (Kd), and dynamic magnification (Kd / Ks) according to the following JIS standards. The results are also shown in Table 1.

[Compression set characteristics]
A compression set test was performed in accordance with JIS K 6262 under a heating temperature condition of 100 ° C. for 72 hours.
[Static spring constant (Ks), dynamic spring constant (Kd), and dynamic magnification (Kd / Ks)]
According to JIS K 6385, Kd was measured at 100 Hz.

  Details of the above formulation are as follows.

Rubber component (1) Natural rubber (NR): “RSS # 4”
(2) High cis-butadiene rubber (BR): “BR01” manufactured by JSR (cis content 95% or more)
(3) Low cis butadiene rubber (BR): "Diene NF35R" (cis content 35%) manufactured by Asahi Kasei Corporation
(4) EPDM: “EP96” manufactured by JSR, ENB content 6.0% by mass, ethylene content 66% by mass (when the rubber component is “100 parts by mass”, 50 parts by mass of oil is included.)
(5) End-modified butadiene rubber: Product name “Nippol BR1250H” manufactured by Nippon Zeon

(6) FEF grade carbon black: “N550” manufactured by Asahi Carbon Co., Ltd.
(7) HAF grade carbon black: “ASAHI # 70-NP” manufactured by Asahi Carbon Co., Ltd.

(8) Anti-aging agent: N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine, “NOCRACK 6C” manufactured by Ouchi Shinsei Chemical Co., Ltd.
(9) Wax: “Sun Tite S” manufactured by Seiko Chemical Co., Ltd.

(10) Vulcanization accelerator NS: Trade name “Noxeller NS” (Ouchi Shinsei Chemical Co., Ltd.)
(11) Vulcanization accelerator TBT: Trade name “Noxeller TBT” (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.)

(12) Peroxide: di (2-t-butylperoxyisopropyl) benzene, “NOVA CO., LTD.” “Peroximon F-40”

(13) Co-crosslinking agent (i) Zinc diacrylate (ZAA), “SR633” manufactured by Sartomer
(Ii) Zinc dimethacrylate (ZMA), “SR634” manufactured by Sartomer
(Iii) Magnesium methacrylate, “High Cross GT” manufactured by Seiko Chemical Co., Ltd.

As can be seen from the results in Table 1, the rubber compositions of Examples 1 to 6 according to the present invention are ternary systems in which NR and EPDM are blended at a specific ratio, and a part of NR is substituted with terminal-modified BR. A rubber component is blended with a peroxide as a vulcanizing agent and a combination of zinc acrylate and / or zinc methacrylate as a co-crosslinking agent. As a result, the rubber compositions of Examples 1 to 6 were able to improve both the creep resistance and the dynamic ratio at the same time as compared with the comparative examples.
On the other hand, Comparative Example 1 uses only NR as the rubber component, but the compression set was very large and the creep resistance was poor. In Comparative Examples 2 and 3, NR and EPDM were mixed as rubber components, but the dynamic magnification and compression set characteristics were poor. Comparative Examples 4 and 5 were used by replacing a part of NR / EPDM as a rubber component with BR having a high cis content, but the improvement in dynamic magnification and creep resistance were not as great as those in Examples. . Comparative Examples 6 to 8 were used by replacing a part of NR / EPDM as a rubber component with BR having a low cis content, but the dynamic magnification and the improvement degree of creep resistance were not as great as those of Examples. . In Comparative Example 9, NR and EPDM were mixed as rubber components, but the dynamic magnification and compression set characteristics were poor.

Claims (2)

  As a rubber component, natural rubber (NR), ethylene / propylene / diene rubber (EPDM) and terminal-modified butadiene rubber (terminal-modified BR) are (NR) / (EPDM) / (terminal-modified BR) = 45 to 65 in mass ratio. Anti-vibration rubber composition characterized by containing a ratio of / 30 to 45/5 to 20, a peroxide as a vulcanizing agent, and zinc acrylate and / or zinc methacrylate as a co-crosslinking agent .   An anti-vibration rubber obtained by curing the rubber composition according to claim 1.