JP5459156B2 - Anti-vibration rubber composition and anti-vibration rubber - Google Patents

Description

  The present invention relates to a heat-resistant and vibration-proof rubber composition that can be suitably used in a high-temperature environment, and a vibration-proof 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.

  The anti-vibration rubber is disposed in a site that is a source of vibration and noise in order to improve the comfort of passengers in various vehicles such as automobiles. In order to reduce the intrusion of vibration and noise into the room, for example, vibration-proof rubber is used for components such as torsional dampers, engine mounts, and muffler hangers for engines that are the main sources of vibration and noise. This absorbs vibrations when the engine is driven, reducing the intrusion of vibrations and noise into the room and the spread of noise into 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 anti-vibration performance, as well as high heat resistance, ozone resistance and creep resistance. 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 that of synthetic rubber, so that heat resistance and ozone resistance are insufficient when used in a high temperature environment.

  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-resistant rubber composition in which a heat-resistant vibration-proof rubber having improved durability is obtained by subjecting a specific EPDM to peroxide crosslinking. Yes. However, with these methods, there is a risk that the rubber properties such as tensile strength (normal temperature, high temperature), tearability, 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. And a rubber composition obtained by vulcanization with an organic peroxide using an ethylene-α-olefin copolymer rubber containing no conjugated diene (Japanese Patent Laid-Open No. 8-127673: Patent Document 4) Anti-vibration rubber (Japanese Patent Laid-Open No. 1-299806: Patent Document 5) and the like excellent in mechanical rigidity have been proposed, but further improvement is desired. In addition, in order to obtain a heat-resistant rubber composition capable of obtaining excellent vibration-proof performance, a technique using only a specific bismaleimide compound as a vulcanizing agent in a diene rubber (Japanese Patent Laid-Open No. 2006-273941: 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 set resistance (Japanese Patent Application No. 2009-195021). However, even in this proposal, there was a slight decrease in tensile physical properties, which is one of the required properties of vibration-proof rubber, and there was still room for improvement.

  Therefore, in general, rubber compositions such as anti-vibration rubber, which are considered to have a trade-off relationship between heat resistance and tensile physical properties, have excellent rubber compositions in both heat resistance and tensile physical properties (elongation, strength). Development was desired.

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 a vibration-proof rubber composition from which a rubber cured product capable of improving creep resistance is obtained while maintaining heat resistance, tensile physical properties (elongation, strength) and low dynamic magnification, Another object is to provide an anti-vibration rubber obtained by curing the rubber composition.

  As a result of intensive studies to achieve the above object, the present inventor has blended NR and EPDM at a specific ratio to form a rubber component, and a peroxide as a vulcanizing agent and a co-crosslinking agent. , (A) Zinc acrylate or zinc methacrylate and (B) Citraconimide compound were found to improve creep resistance while maintaining a low dynamic magnification, and led to the present invention. It is.

Accordingly, the present invention provides the following anti-vibration rubber composition and anti-vibration rubber.
[1] Natural rubber (NR) and ethylene / propylene / diene rubber (EPDM) are contained as a rubber component in a mass ratio of NR / EPDM = 70/30 to 45/55, and a peroxide as a vulcanizing agent. And an anti-vibration rubber composition comprising (A) zinc acrylate or zinc methacrylate and (B) a citraconimide compound as a co-crosslinking agent.
[2] The anti-vibration rubber composition according to [1], wherein the (B) citraconimide compound is a biscitraconimide compound.
[3] X parts by mass of (A) zinc acrylate or zinc methacrylate with respect to 100 parts by mass of rubber component, X parts by mass of (B) citraconic compound, and Y + parts by mass of the co-crosslinking agent. = When Z parts by mass
0.5 ≦ X ≦ 4.0
0.5 ≦ Y ≦ 6.0
5.0 ≦ Z ≦ 7.0
The anti-vibration rubber composition according to [1] or [2], wherein
[4] An anti-vibration rubber obtained by curing the rubber composition according to [1], [2] or [3].

  The anti-vibration rubber composition of the present invention can improve creep resistance while maintaining the tensile physical properties and low dynamic magnification after heat aging.

  The anti-vibration rubber composition of the present invention contains natural rubber (NR) and ethylene / propylene / diene rubber (EPDM) in a predetermined ratio as rubber components, a peroxide as a vulcanizing agent, and as a co-crosslinking agent. (A) Zinc acrylate or zinc methacrylate, and (B) Citraconimide compound.

  The rubber component includes NR and EPDM. At that time, the blending ratio of NR and EPDM is usually in the range of NR / EPDM = 70/30 to 45/55 in terms of mass ratio. If the ratio of EPDM is less than the above range, ozone resistance and heat resistance may be reduced, and if it is too high, dynamic magnification may be increased, and durability and strength may be reduced. The NR and EPDM may be appropriately selected from known ones and are not particularly limited.

  Further, 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 rubbers such as a known synthetic rubber are used in addition to the rubber component as necessary. May be used in combination. Specific examples thereof include butadiene rubber, styrene / butadiene rubber, isoprene rubber, chloroprene rubber, isobutylene / isoprene rubber, acrylonitrile / butadiene rubber, silicone rubber, acrylic rubber, epoxidized natural rubber, acrylate butadiene 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 the amount of the rubber is compounded, 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, it is superior in heat resistance and creep resistance at high temperature as compared with the case of crosslinking using sulfur. Further, the heat resistance and durability of the anti-vibration rubber can be improved. 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.

  The co-crosslinking agent is not itself capable of generating a crosslinking point, but is an additive that causes a crosslinking reaction in the rubber when used in combination with the above-described peroxide, in order to obtain the desired effect of the present invention. (A) Zinc acrylate or zinc methacrylate, and (B) Citraconimide compound are included as essential components.

  (A) Although there is no restriction | limiting in particular about the compounding quantity of zinc acrylate or zinc methacrylate, Preferably it is 0.5 mass part or more with respect to 100 mass parts of said rubber components, More preferably, it is 1.0 mass part or more, More preferably, it is 1.5 parts by mass or more, and the upper limit is preferably 4.0 parts by mass or less, more preferably 3.8 parts by mass or less, and further preferably 3.5 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 below the above range, the rubber is not sufficiently cross-linked, resulting in a decrease in breaking strength and dynamic magnification. May cause an increase in compression and an increase in compression set.

  In the present invention, the fatty acid ester can also be blended with the rubber component together with the above (A) zinc acrylate or zinc methacrylate, whereby the dispersibility of the zinc acrylate or zinc methacrylate with respect to the rubber component during kneading. And 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.

  This fatty acid ester exhibits an effect of improving dispersibility even when blended separately with the above-described (A) zinc acrylate or zinc methacrylate at the time of kneading with the rubber component, but before kneading with the rubber component ( The dispersibility of (A) zinc acrylate or zinc methacrylate in the rubber component can be further improved by premixing with A) zinc acrylate or zinc methacrylate.

  Moreover, in this invention, (B) citraconimide compound is used as an essential component as a co-crosslinking agent, and it uses together with said (A) zinc acrylate or zinc methacrylate. (B) Although there is no restriction | limiting in particular about a citraconic imide compound, It is suitable to use bis citraconic imides. Preferred examples of biscitraconimides include compounds represented by the following general formula.

（式中、Ａｒはアリーレン基、Ｑ₁ 及びＱ₂ は、それぞれ独立して、炭素数１〜４のアルキレン基を示す。）

(In the formula, Ar represents an arylene group, and Q ₁ and Q ₂ each independently represents an alkylene group having 1 to 4 carbon atoms.)

In the above general formula (I), the arylene group represented by Ar is preferably an arylene group having 6 to 20 carbon atoms, which may or may not have a substituent on the ring. Although there is no restriction | limiting in particular as said substituent, Specifically, a lower alkyl group, an alkoxyl group, a halogen atom, a nitro group, a cyano group etc. can be mentioned. Examples of the arylene group include a phenylene group and a naphthylene group, and a phenylene group is particularly preferable. On the other hand, Q ₁ and Q ₂ each represent an alkylene group having 1 to 4 carbon atoms, and the alkylene group may be linear or branched. Examples of such an alkylene group include a methylene group, an ethylene group, a propylene group, and a butylene group. Q ₁ and Q ₂ may be the same as or different from each other, and are preferably the same from the viewpoint of ease of manufacture. Specific examples of the compound represented by the general formula (I) include 1,2-bis (citraconimidomethyl) benzene; 1,3-bis (citraconimidomethyl) benzene; 1,4-bis (citraconimidomethyl). Benzene; 2,3-bis (citraconimidomethyl) toluene; 2,4-bis (citraconimidomethyl) toluene; 2,5-bis (citraconimidomethyl) toluene, 2,6-bis (citraconimidomethyl) toluene, And bis (citraconimidoethyl) compounds corresponding to these. Among these, it is preferable to use 1,3-bis (citraconimidomethyl) benzene from the viewpoint of sufficiently exerting the effects of the present invention.

  1,3-bis (citraconimidomethyl) benzene is a compound represented by the following formula, and specifically, a trade name “PERKALINK 900” (manufactured by Flexis) can be used.

  In the present invention, the (B) citraconimide compound can be used in combination of not only one type but also two or more types. (B) Although there is no restriction | limiting in particular about the compounding quantity of a citraconic imide compound, Preferably it is 0.5 mass part or more with respect to 100 mass parts of said rubber components, More preferably, it is 1.0 mass part or more, More preferably, it is 2 The upper limit value is preferably 6.0 parts by mass or less, more preferably 4.5 parts by mass or less, and still more preferably 4.0 parts by mass or less. If the blending amount exceeds the above range, the tensile elongation, tensile strength, dynamic magnification and the like may be increased. If the blending amount is less than the above range, compression set may be deteriorated.

  Further, the blending amount of (A) zinc acrylate or zinc methacrylate with respect to 100 parts by weight of the rubber component is X parts by weight, the blending amount of (B) citraconimide compound is Y parts by weight, and the total weight of the co-crosslinking agent is X + Y = When Z parts by mass are satisfied, 5.0 ≦ Z ≦ 7.0 is preferably satisfied from the viewpoint of effectively exhibiting the effects of the present invention. If it deviates from this range, tensile elongation, tensile strength, increase in dynamic magnification, and deterioration of compression set may be caused.

  In addition, for the rubber component, a vulcanizing agent, a vulcanization accelerator, an anti-aging agent, carbon, silica, zinc white, which are usually used in the rubber industry, are used as long as the effects of the present invention are not impaired. Additives such as (ZnO), waxes, antioxidants, fillers, foaming agents, plasticizers, oils, lubricants, tackifiers, petroleum resins, ultraviolet absorbers, dispersants, compatibilizers, homogenizers, etc. 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.

  Known carbon can be used, and is not particularly limited. Examples thereof include carbon black such as SRF, GPF, FEF, HAF, ISAF, SAF, FT, MT, In the present invention, FT or FEF can be suitably 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 phenol-based anti-aging agents, imidazole-based anti-aging agents, and amine-based anti-aging agents. 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 to 9, Comparative Examples 1 and 2]
Kneaded with the composition shown in Table 1 below and vulcanized to a sample shape conforming to JIS, hardness (Hd), tensile elongation (Eb), tensile strength (Tb), heat resistance (thermal aging test), compression set (%), Static spring constant (Ks), and dynamic magnification (Kd / Ks) were measured and evaluated according to the following JIS standards. The results are shown in Table 1.

[Hardness (Hd)]
Conforms to JIS K 6253 (Type A) [Tensile elongation (Eb)]
Conforms to JIS K 6251. When Eb was 400% or more, it was judged as “good”.
[Tensile strength (Tb)]
Conforms to JIS K 6251. When Tb was 10 MPa or more, it was judged as “good”.
[Heat resistance (heat aging test)]
In accordance with JIS K 6257, the test piece was allowed to stand under conditions of 120 ° C. and 96 hours, and then the hardness (Hd), tensile elongation (Eb), and tensile strength (Tb) were measured.
Moreover, change value (DELTA) Hd was shown about hardness (Hd), and the retention (%) was shown about tensile elongation (Eb) and tensile strength (Tb). The target value of Eb retention was set to 90% or more, and the target value of Tb retention was set to 80% or more.
[Compression set]
Conforms to JIS K 6262. The target value was within 25% of compression set (CS).
[Static spring constant (Ks), dynamic spring constant (Kd), and dynamic magnification (Kd / Ks)]
According to JIS K 6385, Kd was measured at 100 Hz. The dynamic magnification (Kd / Ks) was set to a target value within 1.4.

Details of the above formulation are as follows.
(1) NR: Natural rubber, “RSS # 1”
(2) EPDM: “EP96” manufactured by JSR, ENB content 6.0% by mass, ethylene content 66% by mass (polymer component: 30 phr, oil component: 15 phr)
(3) FT grade carbon black: "Asahi Thermal" made by Asahi Carbon
(4) Anti-aging agent: 2,2,4-trimethyl-1,2-dihydroquinoline polymer, “NOCRACK 224” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
(5) Peroxide: di (2-t-butylperoxyisopropyl) benzene, “Peroximon F-40” manufactured by NOF Corporation
(6) Zinc acrylate (ZA): “SR633” manufactured by Sartomer
(7) Biscitraconimides: 1,3-bis (citraconimidomethyl) benzene “PERKALINK 900” (manufactured by Flexis)

As shown in Table 1 above, the rubber compositions of the examples according to the present invention were blended with NR and EPDM at a specific ratio to form a rubber component, and a peroxide as a vulcanizing agent and a co-crosslinking agent. , (A) zinc acrylate or zinc methacrylate, and (B) a citraconimide compound. As a result, in the rubber compositions of these examples, the low dynamic magnification is maintained well, the tensile properties such as elongation and strength after heat aging are maintained, and the creep resistance (compression set) is sufficiently improved. It was confirmed that
On the other hand, although the low dynamic magnification was favorable, the comparative example 1 was inferior to creep resistance (compression set). Although the comparative example 2 is an example which mix | blended the citraconimide compound independently as a co-crosslinking agent, the target value of the tensile physical property was not able to be cleared.

Claims (4)

  The rubber component includes natural rubber (NR) and ethylene / propylene / diene rubber (EPDM) in a mass ratio of NR / EPDM = 70/30 to 45/55, and also includes a peroxide as a vulcanizing agent. A vibration-insulating rubber composition comprising (A) zinc acrylate or zinc methacrylate and (B) a citraconic compound as a co-crosslinking agent.   The anti-vibration rubber composition according to claim 1, wherein the (B) citraconimide compound is a biscitraconimide. The blending amount of (A) zinc acrylate or zinc methacrylate with respect to 100 parts by weight of the rubber component is X parts by weight, (B) the blending amount of the citraconimide compound is Y parts by weight, and the total weight part of the co-crosslinking agent is X + Y = Z mass. Part
0.5 ≦ X ≦ 4.0
0.5 ≦ Y ≦ 6.0
5.0 ≦ Z ≦ 7.0
The anti-vibration rubber composition of Claim 1 or 2 satisfy | filling these.   An anti-vibration rubber obtained by curing the rubber composition according to claim 1, 2 or 3.