JP2011144321A - Vibration-proof rubber composition and vibration-proof rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration-proof rubber composition capable of providing a cured rubber which is greatly improved in creep resistance while holding heat resistance, tear resistance, strengths and a low dynamic-to-static modulus ratio; and to provide a vibration-proof rubber prepared by curing the same. <P>SOLUTION: The vibration-proof rubber composition contains a natural rubber (NR) and an ethylene propylene diene rubber (EPDM) in a mass ratio of 70/30 to 45/55 as rubber components, only a peroxide as a vulcanizing agent, and (X) zinc acrylate or zinc methacrylate, and (Y) diacrylic acid or dimethacrylic acid lower alkylene glycols as co-crosslinking agents. <P>COPYRIGHT: (C)2011,JPO&INPIT

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.

  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 anti-vibration performance, as well as heat resistance, ozone resistance, and creep resistance. It is required to have high performance. In addition, excellent tear resistance is an important issue as one of the characteristics of the vibration-proof rubber.

  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.

  In addition, in the conventionally proposed technology, in order to greatly improve the creep resistance, one of heat resistance, strength, and low dynamic magnification must be sacrificed. In addition, in Japanese Patent Application No. 2008-156225 previously proposed by the applicant of the present application, natural rubber (NR) and ethylene / propylene / diene rubber (EPDM) are used as rubber components, and NR / EPDM = 70/30 to 45 by mass ratio. An anti-vibration rubber composition containing a ratio of / 55 and premixed with zinc acrylate and a fatty acid ester is described.

  However, the rubber composition using zinc acrylate or zinc methacrylate as a co-crosslinking agent as described above is excellent in heat resistance and tensile physical properties, but inferior in creep resistance.

  In order to solve the above problems, Japanese Patent Application No. 2009-195021 proposes to use zinc acrylate and a bismaleimide compound together as a rubber component (NR / EPDM) co-crosslinking agent. In the rubber composition, a slight decrease in elongation was observed in the tensile properties, and the vibration-insulating rubber assembly performance was not fully satisfactory.

JP 2009-298949 A

  The present invention has been made in view of the above circumstances, and a vibration-proof rubber composition from which a cured rubber can be obtained that can significantly improve creep resistance while maintaining heat resistance, tear resistance, 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 into a rubber component, and blends only a peroxide as a vulcanizing agent and a co-crosslinking agent. (X) zinc acrylate or methacrylate and (Y) diacrylic acid or dimethacrylic acid lower alkylene glycols are included so that the conventional technology has a heat resistance to greatly improve the creep resistance. However, in the rubber composition of the present invention, while maintaining heat resistance, tear resistance, strength and low dynamic magnification, it has to be sacrificed. The inventors have found that the creep property can be greatly improved, and have reached the present invention.

［但し、式（Ｉ），（ＩＩ）中のＡＯは、それぞれ、エチレンオキサイド、プロピレンオキサイド又はブチレンオキサイドから選ばれる。また、式（Ｉ），（ＩＩ）中のｎは、それぞれ１〜４の整数を表す。］
に示されるジアクリル酸又はジメタクリル酸低級アルキレングリコール類を含むことを特徴とする防振ゴム組成物。
［２］ゴム成分１００質量部に対するアクリル酸亜鉛またはメタクリル酸亜鉛の配合量をＸ質量部、ジアクリル酸又はジメタクリル酸低級アルキレングリコール類の配合量をＹ質量部、共架橋剤の総質量部をＸ＋Ｙ＝Ｚ質量部としたとき、
１．５≦Ｘ≦４．０
０．４≦Ｙ≦３．２
４．０≦Ｚ≦５．０
を満たす［１］記載の防振ゴム組成物。
［３］［１］又は［２］記載のゴム組成物を硬化させてなる防振ゴム。 Accordingly, the present invention provides the following rubber composition for vibration-proof rubber and vibration-proof 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 (X) zinc acrylate or zinc methacrylate, and (Y) the following general formula (I) or (II)

[However, AO in the formulas (I) and (II) is selected from ethylene oxide, propylene oxide, or butylene oxide, respectively. Moreover, n in Formula (I) and (II) represents the integer of 1-4, respectively. ]
A vibration-insulating rubber composition comprising a dialkylic acid or dimethacrylic acid lower alkylene glycol represented by the formula:
[2] X parts by mass of zinc acrylate or zinc methacrylate with respect to 100 parts by mass of the rubber component, Y parts by mass of diacrylic acid or dialkyl methacrylate lower alkylene glycol, and total parts by mass of the co-crosslinking agent When X + Y = Z parts by mass,
1.5 ≦ X ≦ 4.0
0.4 ≦ Y ≦ 3.2
4.0 ≦ Z ≦ 5.0
The anti-vibration rubber composition according to [1], wherein
[3] A vibration-proof rubber obtained by curing the rubber composition according to [1] or [2].

  The anti-vibration rubber composition of the present invention can greatly improve creep resistance while maintaining heat resistance, tear resistance, strength and low dynamic magnification.

  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, contains only peroxide as a vulcanizing agent, and is a co-crosslinking agent. As (X) zinc acrylate or zinc methacrylate, and (Y) specific diacrylic acid or dimethacrylic acid lower alkylene glycols.

  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, only peroxide is used in the present invention. In the present invention, by peroxide-crosslinking the rubber component using only a peroxide as a vulcanizing agent, heat resistance and creep resistance at high temperatures are excellent as compared with the case of crosslinking using sulfur. Therefore, 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. , (X) zinc acrylate or zinc methacrylate, and (Y) diacrylic acid or dimethacrylic acid lower alkylene glycols as essential components.

  (X) Although there is no restriction | limiting in particular in the compounding quantity of zinc acrylate or zinc methacrylate, Preferably it is 1.5 mass parts or more with respect to 100 mass parts of said rubber components, More preferably, it is 2.0 mass parts or more. The upper limit is preferably 4.0 parts by mass or less, more preferably 3.8 parts by mass or less. If the blending amount exceeds the above range, the rubber may be excessively cured, leading to a decrease in elongation at break, and if the blending amount is below the above range, the rubber is not sufficiently crosslinked, resulting in a decrease in the breaking strength and a tear strength. There is a risk of lowering the rotation rate, increasing the dynamic magnification, and increasing the compression set.

  In the present invention, the fatty acid ester can be blended with the rubber component together with the (X) zinc acrylate or zinc methacrylate, thereby 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 the effect of improving dispersibility even when blended separately with the zinc acrylate or zinc methacrylate when kneaded with the rubber component. By premixing with zinc methacrylate, the dispersibility of zinc acrylate or zinc methacrylate in the rubber component can be further improved.

  In the present invention, as a co-crosslinking agent, (Y) diacrylic acid or lower alkylene glycol dimethacrylate is used as an essential component, and is used in combination with the above (X) zinc acrylate or zinc methacrylate.

［但し、式（Ｉ），（ＩＩ）中のＡＯは、それぞれ、エチレンオキサイド、プロピレンオキサイド又はブチレンオキサイドから選ばれる。また、式（Ｉ），（ＩＩ）中のｎは、それぞれ１〜４の整数を表す。］
に示されるものが用いられる。即ち、低級アルキレングリコールとは、例えば、モノエチレングリコール，ジエチレングリコール，トリエチレングリコール，ポリエチレングリコール等の（ポリ）エチレングリコールや、モノプロピレングリコール，ジプロピレングリコール，トリプロピレングリコール，ポリプロピレングリコール等の（ポリ）プロピレングリコール、１，２−プロパンジオール、１，３−プロパンジオール等の（ポリ）プロパンジオール、１，２−ブタンジオール、１，３−ブタンジオール、１，４−ブタンジオール等の（ポリ）ブタンジオールなどが挙げられる。これらは１種単独で用いてもよく、或いは２種以上が分子構造内に含まれていてもよい。低級アルキレングリコールには、特に制限はないが、より好ましくはエチレングリコールであり、上記式（Ｉ），（ＩＩ）中のｎ＝１〜４のうち、ｎが１であることが好適である。この低級アルキレングリコールの炭素数が多くなると、圧縮永久歪みの悪化を招くおそれがある。また、ｎの値が多くなると、圧縮永久歪みの悪化を招くおそれがある。 Here, as (Y) diacrylic acid or dimethacrylic acid lower alkylene glycols, specifically, the following general formula (I) or (II)

[However, AO in the formulas (I) and (II) is selected from ethylene oxide, propylene oxide, or butylene oxide, respectively. Moreover, n in Formula (I) and (II) represents the integer of 1-4, respectively. ]
The one shown in is used. That is, the lower alkylene glycol is, for example, (poly) ethylene glycol such as monoethylene glycol, diethylene glycol, triethylene glycol, or polyethylene glycol, or (poly) such as monopropylene glycol, dipropylene glycol, tripropylene glycol, or polypropylene glycol. (Poly) propanediol such as propylene glycol, 1,2-propanediol, 1,3-propanediol, (poly) butane such as 1,2-butanediol, 1,3-butanediol, 1,4-butanediol Examples include diols. These may be used individually by 1 type, or 2 or more types may be contained in the molecular structure. Although there is no restriction | limiting in particular in lower alkylene glycol, More preferably, it is ethylene glycol, It is suitable that n is 1 among n = 1-4 in the said formula (I), (II). If the number of carbon atoms of the lower alkylene glycol is increased, the compression set may be deteriorated. Further, when the value of n increases, the compression set may be deteriorated.

  (Y) Although there is no restriction | limiting in particular about the compounding quantity of diacrylic acid or dimethacrylic acid lower polyalkylene glycol, Preferably it is 0.4 mass part or more with respect to 100 mass parts of said rubber components, More preferably, it is 0.8. The upper limit is preferably 3.2 parts by mass or less, more preferably 2.8 parts by mass or less. If the blending amount exceeds the above range, the tensile elongation, the tensile strength, the tearability may decrease, the dynamic magnification may increase, and if the blending amount is less than the above range, the compression set may deteriorate. .

  Further, the blending amount of 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 diacrylic acid or lower alkylene glycols with diacrylic acid is Y parts by weight, and the total weight part of the co-crosslinking agent is X + Y. = Z parts by mass, it is preferable to satisfy 4.0 ≦ Z ≦ 5.0, more preferably 4.2 ≦ Z ≦ 4.8, from the viewpoint of effectively exhibiting the effects of the present invention. . If it deviates from this range, the tensile elongation, the tensile strength, the tearability may be lowered, the dynamic magnification may be increased, and the compression set may be deteriorated.

  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 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 a 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 one time. 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 1-11, Comparative Examples 1-10]
The rubber composition for vibration-proof rubber of each of Examples 1 to 11 and Comparative Examples 1 to 10 was vulcanized and cured under predetermined conditions by kneading and vulcanizing with the blending compositions shown in Tables 1 and 2 below. A sheet molded product having a thickness of 120 mm, a width of 120 mm, and a thickness of 2 mm was produced. This sheet was used as an evaluation body of the vibration-proof rubber of the present invention. About the obtained rubber sheet, hardness (Hd), tensile elongation (Eb), tensile strength (Tb), heat resistance (thermal aging test), tear resistance (Tr), compression set (%), static spring constant (Ks) and dynamic magnification (Kd / Ks) were measured and evaluated according to the following JIS standards. The results are also shown in Tables 1 and 2.

[Hardness (Hd)]
Conforms to JIS K 6253 (Type A) [Tensile elongation (Eb)]
Conforms to JIS K 6251. When Eb was 500% or more, it was judged as “good”.
[Tensile strength (Tb)]
Conforms to JIS K 6251. When Tb was 15 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 the conditions of 100 ° C. and 96 hours, and then the hardness (Hd), tensile elongation (Eb), and tensile strength (Tb) were measured. For hardness (Hd), change values (degrees) are shown, and for tensile elongation (Eb) and tensile strength (Tb), retention (%) is shown.
[Tear resistance (Tr)]
Conforms to JIS K 6252. The test piece was an angle test piece without a cut and was judged as “good” when Tr was 35 N / mm or more.
[Compression set]
Conforms to JIS K 6262. The target value was within 30% 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.

（８）ジメタクリル酸ジエチレングリコール（ｎ＝２）
：日油社製、商品名「ブレンマーＰＤＥ−１００」

（９）ポリエチレングリコールジアクリレート（ｎ＝９）
：新中村化学工業社製、商品名「ＮＫエステルＡ−４００」

（１０）マグネシウムジメタクリレート
：精工化学社製、商品名「ハイクロスＧＴ」 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) Ethylene glycol dimethacrylate (n = 1)
: Made by Seiko Chemical Co., Ltd., trade name “Hi-Cross ED-P”
(Trade name “Sunester EG”, manufactured by Sanshin Chemical Co., Ltd.)

(8) Diethylene glycol dimethacrylate (n = 2)
: Product name "Blemmer PDE-100" manufactured by NOF Corporation

(9) Polyethylene glycol diacrylate (n = 9)
: Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester A-400”

(10) Magnesium dimethacrylate: manufactured by Seiko Chemical Co., Ltd., trade name “High Cross GT”

  As shown in Tables 1 and 2 above, the rubber compositions of the examples according to the present invention blend NR and EPDM at a specific ratio to form a rubber component, and blend only peroxide as a vulcanizing agent. As a co-crosslinking agent, (X) zinc acrylate or zinc methacrylate, and (Y) specific diacrylic acid or dialkyl methacrylate lower alkylene glycols are blended in combination. As a result, in the rubber compositions of these Examples, the creep resistance (compression set) can be greatly improved while maintaining good heat resistance, tear resistance, strength and low dynamic magnification. Was confirmed.

Claims (3)

Natural rubber (NR) and ethylene / propylene / diene rubber (EPDM) are included as a rubber component in a mass ratio of NR / EPDM = 70/30 to 45/55, and only a peroxide is included as a vulcanizing agent. And (X) zinc acrylate or zinc methacrylate, and (Y) the following general formula (I) or (II)

[However, AO in the formulas (I) and (II) is selected from ethylene oxide, propylene oxide, or butylene oxide, respectively. Moreover, n in Formula (I) and (II) represents the integer of 1-4, respectively. ]
A vibration-insulating rubber composition comprising a dialkylic acid or dimethacrylic acid lower alkylene glycol represented by the formula: X parts by weight of zinc acrylate or zinc methacrylate with respect to 100 parts by weight of the rubber component, Y parts by weight of diacrylic acid or lower alkylene glycols of dimethacrylic acid, and X + Y = Z When the mass part
1.5 ≦ X ≦ 4.0
0.4 ≦ Y ≦ 3.2
4.0 ≦ Z ≦ 5.0
The anti-vibration rubber composition according to claim 1 satisfying   Anti-vibration rubber obtained by curing the rubber composition according to claim 1.