JPH10196719A - Damper pulley - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a damper pulley which can display stabilized vibration control performance even under high-temperature atmosphere. SOLUTION: It is a damper pulley which is composed of an elastic body 16 intervening between a damper mass 12 and a pulley 14. The elastic body 16 is a vulcanized material of peroxide vulcanized rubber compound of which base is a polymer alloy which satisfies the following requirements (1)-(3), and is composed of a material of which loss tangent (tan δ) is 0.20-0.35. (1) The polymer alloy is an EPDM on which liquid EPM is added. (2) Of EPDM, a molecular weight distribution index (Mw /Mn ) measured by GPC method is less than 4, ultimate viscosity [η] measured in 135 deg.C decalin is about 2.7-5.0dL/g, iodine value is 10-40, and non-conjugate diene is 5-ethyliden-2-norbornen. (3) The ultimate viscosity [η] of liquid EPM is 0.30-0.6dL/g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a damper pulley having an elastic body interposed between a damper mass and a pulley.

In particular, a damper mass (hub) 12 and a pulley 1
The present invention is suitable for a damper pulley 18 of a type in which the elastic body 16 is simply press-fitted between the elastic body 16 and the damper pulley 4 (see FIG. 1). The present invention is also applicable to a damper pulley of a type in which an elastic body is used as an adhesive or a ring is press-fitted.

[0003] The meanings of the following characteristic values in the columns of "claims" and "detailed description of the invention" in this specification are as follows.

[0004] Loss tangent (tan δ): a value determined by a dynamic viscoelasticity test described later.

[0005] Intrinsic viscosity [η]: measured at 135 ° C in decalin.

The molecular weight distribution index (M_W / M_n ): Described later
Gel permeation chromatography (GPC method)
Weight average molecular weight in molecular weight distribution determined by measurement
(M _W ) Is the number average molecular weight (M_n Index divided by).

In the following description, the blending unit is a weight unit unless otherwise specified.

[0008]

2. Description of the Related Art The elastic body of a conventional damper pulley is formed of a rubber material such as NR / SBR, SBR, chlorinated IIR, NBR, hydrogenated NBR, etc.
297557).

[0009]

However, it is difficult for these rubber materials to respond to the recent demand for improvement in heat resistance due to a rise in temperature in the engine room.

Therefore, it is generally considered to use an ethylene propylene rubber-based material having excellent heat resistance, that is, an ethylene / α-olefin copolymer rubber (EOR) material.

However, a general-purpose EOR has problems that it is inferior in low-temperature flexibility and has a small loss tangent (tan δ).

Therefore, the present inventors have proposed a specific ternary EOR rubber (ethylene-ethylene rubber) previously proposed by one of the present applicants.
For heat and vibration proof of sulfur vulcanization system based on polymer alloy composed of α-olefin / non-conjugated diene copolymer rubber) and specific liquid binary EOR (liquid ethylene / α-olefin copolymer rubber) By paying attention to the rubber composition (rubber compound) (Japanese Patent Application Laid-Open No. 6-001819), it was examined whether or not it can be applied to a damper pulley.

However, when an elastic body molded from the EOR blend rubber material is applied to a damper pulley, the elastic body has a large change in hardness (ΔH _S ) after thermal degradation, and a large resonance frequency change depending on the hardness. In addition, it is difficult to obtain stable damper pulley performance, and when applied to the simple press-fitting type as described above, there is a problem in set resistance (high compression set (CS) after a thermal test), and damper mass and / or It was found that there was a problem in the connection between the pulley and the elastic body (see Comparative Example in Table 1). That is, the heat resistance was not always sufficient to satisfy the required performance of the damper pulley.

In view of the above, an object of the present invention is to provide a damper pulley capable of exhibiting a stable vibration-proof performance even in a high-temperature atmosphere.

Another object of the present invention is to provide a high-temperature atmosphere,
An object of the present invention is to provide a damper pulley of a simple press-fit type that does not easily cause a problem in damper mass and / or connectivity between the pulley and the elastic body.

[0016]

Means for Solving the Problems In order to solve the above-mentioned problems, the inventors of the present invention have sought to develop a vulcanization system in the rubber compound for heat and vibration proof while working hard on development. The present inventors have found that the above problem can be solved by forming the elastic body of the damper pulley with a liquid binary EOR having a limiting viscosity shifted, and have arrived at a damper pulley having the following configuration.

In the damper pulley in which an elastic body is interposed between the damper mass and the pulley, the elastic body has the following requirements.
A peroxide vulcanized vulcanizate based on a polymer alloy satisfying (1) to (3) and having a loss tangent (tan δ) of 0.20 to 0.35. It is characterized by being.

(1) The polymer alloy is an ethylene / α-olefin / non-conjugated diene copolymer rubber (A): 80 to 6
0% by weight and liquid ethylene / α-olefin copolymer rubber (B): 2040% by weight.

(2) The ethylene / α-olefin / non-conjugated diene copolymer rubber comprises ethylene, an α-olefin having 3 to 20 carbon atoms and a non-conjugated diene, and is composed of ethylene and α-olefin. The molar ratio is 60 / 40-73 /
27, a molecular weight distribution index (M _w / M _n ) of less than 4, an intrinsic viscosity [η] of 2.7 to 5.0 dL / g, an iodine value of 10 to 40, and a non-conjugated diene. Is 5-
Ethylidene-2-norbornene.

(3) The liquid ethylene / α-olefin copolymer rubber is composed of ethylene and α-olefin having 3 to 20 carbon atoms, and the molar ratio of ethylene to α-olefin is 50/50 to 50/50. 78/22, and the intrinsic viscosity [η] is 0.3 to 0.6 dL / g.

DETAILED DESCRIPTION OF THE INVENTION The EOR rubber compound forming the elastic body of the damper pulley of the present invention will be described in detail.

The EOR rubber compound is a specific EOR
An unvulcanized peroxide-vulcanized rubber compound comprising an unvulcanized polymer alloy as described below, wherein the loss tangent (tan δ) of the vulcanized product falls within a specific range.

[I] EOR Polymer Alloy The EOR polymer alloy used in the present invention is a specific ethylene / α-olefin / non-conjugated diene copolymer rubber (abbreviated as “ternary EOR”) (A) And a specific liquid ethylene / α-olefin copolymer rubber (“Liquid binary E
OR ”. ) And (B).

Ternary EOR (A) The above ternary EOR (A) is composed of ethylene and C3-C3.
It is a high molecular weight rubber comprising an α-olefin of 20 and a non-conjugated diene.

This ternary EOR (A) is composed of ethylene and α
-Molar ratio with olefin [ethylene / α-olefin]
Is 60/40 to 73/27, preferably 65/35 to 7
0/30. When the above molar ratio is less than 60/40, the strength of the obtained vulcanized rubber tends to decrease. On the other hand, when the above molar ratio exceeds 73/27, the obtained vulcanized rubber tends to have low-temperature flexibility.

Examples of the α-olefin having 3 to 20 carbon atoms include propylene, butene-1, hexene-1, pentene-1, 4-methylpentene-1,
Heptene-1, octene-1, nonene-1, decene-
1, undecene-1, dodecene-1, tridecene-1,
Tetradecene-1, pentadecene-1, hexadecene-
1, heptadecene-1, octadecene-1, nonadecene-1, eicosene-1 and the like. These α-
Olefins are used alone or in combination.
Of these, propylene is particularly preferred.

As the non-conjugated diene, specifically, 5-ethylidene-2-norbornene is used.
The ternary EOR (A) has an iodine value of 10 to 40, preferably 15 to 40, which is an index of the non-conjugated diene content.
25. When the iodine value is less than 10, the obtained rubber composition tends to have a low vulcanization rate. On the other hand, when the iodine value exceeds 40, the heat resistance of the obtained vulcanized rubber tends to decrease.

The ternary EOR has a molecular weight distribution index (M
_W / _Mn ) is less than 4. By using a high molecular weight ternary EOR (A) having such a molecular weight distribution, a vulcanized rubber excellent in mechanical strength characteristics and dynamic fatigue resistance can be provided.

The ternary EOR (A) has an intrinsic viscosity [η] of 2.7 to 5.0 dL / g, preferably 3.5.
４4.5 dL / g. The intrinsic viscosity [η] is 2.7.
If it is less than dL / g, the durability tends to decrease. On the other hand, when the intrinsic viscosity [η] exceeds 5.0 dL / g,
The productivity of polymer synthesis tends to decrease. When a ternary EOR having an intrinsic viscosity [η] in the above range is used, a vulcanized rubber having excellent dynamic fatigue resistance can be obtained.

The above ternary EOR can be produced, for example, by the method described in JP-B-59-14497. That is, a ternary EOR can be obtained by copolymerizing ethylene, an α-olefin having 3 to 20 carbon atoms, and a diene in the presence of a Ziegler catalyst using hydrogen as a molecular weight regulator.

Liquid Binary EOR (B) The liquid binary EOR (B) is a low molecular weight random copolymer composed of ethylene and an α-olefin having 3 to 20 carbon atoms, and has a diene component. Not included.

The above liquid ethylene / α-olefin copolymer is a random copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. The above number of carbon atoms 3 to
As the α-olefin of No. 20, the above ternary EOR
(A) Examples can be used, and among these, propylene is particularly preferable.

In the present invention, the high molecular weight ternary EOR (A) is made to have an effect of improving heat resistance, mechanical strength characteristics, dynamic fatigue resistance and the like, while low molecular weight liquid ethylene / α is used. -The olefin copolymer (B) has heat aging resistance,
The quality was designed so that the workability (fluidity) could be improved.

However, the EOR-based polymer alloy composed of a high molecular weight component and a low molecular weight component, which is simply bimodal, that is, exhibits a molecular weight distribution having two modes, has heat resistance, mechanical strength characteristics, and dynamic resistance due to the high molecular weight component. Of the effect of improving physical properties such as mechanical fatigue and the ratio of the effect of improving workability (fluidity) due to low molecular weight components are in a tug-of-war relationship. However, it is not possible to provide a vulcanized rubber whose physical properties such as fatigue resistance are dramatically improved.

The inventors of the present invention have further studied the low molecular weight component, and found that when a vulcanized rubber was obtained from an EOR-based polymer alloy having a bimodal molecular weight distribution, the vulcanized rubber was constituted. It has been found that low molecular weight components need not be crosslinked as a polymer. That is, it is necessary that the liquid EOR has a molecular weight that does not crosslink even in a peroxide vulcanization system, and that does not have a diene that increases the crosslinking reactivity with a peroxide vulcanizing agent. I found it necessary. When the low molecular weight component is crosslinked, it becomes difficult to obtain the high damping property which is the object of the present invention.

Liquid binary EOR used in the present invention
The molar ratio of ethylene and α-olefin of (B) is 50 /
50-78 / 22 mol%, preferably 50 / 50-70
/ 30, more preferably in the range of 50/50 to 60/40. Since the liquid binary EOR having the above molar ratio in the above range has good thermal stability, the liquid binary EOR is reduced during the kneading operation with the high molecular weight ternary EOR (A) as described above. This does not occur, and there is no carbonization at the time of molding to contaminate the molded article.

The liquid binary EOR (B) has an intrinsic viscosity [η] of 0.3 to 0.6 dL / g, preferably 0.30 dL / g.
０．４0.45 dL / g. If the intrinsic viscosity [η] is out of the above range, it is difficult to obtain the damping property (damping property) required for the damper pulley.

The reason is that when the intrinsic viscosity exceeds 0.6, most of the low molecular weight components are presumed to be cross-linked and lose the property (damping property) of relaxing to dynamic strain. Would. In the case of a molecular weight showing an intrinsic viscosity falling within the range of the present invention, each molecule can move freely in the vulcanized rubber, which can contribute to the damping property. In addition,
When the intrinsic viscosity (molecular weight) is as low as that of oil, and shows Newtonian viscosity, it does not show damping.

That is, it has a plasticizing effect (hardness lowering effect) equivalent to that of oil and is in the range of the intrinsic viscosity (molecular weight) showing non-Newtonian viscosity, and the damping pulley required for the damper pulley is first exhibited. You. On the other hand, if the intrinsic viscosity (molecular weight) is too high, it is difficult to obtain the effect of improving the processability (fluidity) of the liquid binary EOR.

The above liquid ethylene / α-olefin copolymer can be produced, for example, by the method described in Japanese Patent Publication No. 2-1163. That is, in the presence of a Ziegler catalyst, hydrogen is used as a molecular weight regulator, and ethylene and an α-olefin having 3 to 20 carbon atoms are randomly copolymerized to obtain a liquid ethylene / α-olefin copolymer. Can be.

Production of EOR Polymer Alloy In the EOR polymer alloy [I] used in the present invention, the ternary EOR (A) having a high molecular weight is converted into a ternary EOR.
(A) and liquid binary EOR (B) total amount 100%
And the low molecular weight liquid ethylene / α-olefin copolymer (B) is present in an amount of 20 to 4% based on 100% of the total amount of the above (A) and (B).
Present at 0% rate.

The EOR polymer alloy [I] as described above has a Mooney viscosity ML _{1 + 4} (100 ° C.) of usually 8
0 to 150, preferably 90 to 130, and a molecular weight of 4500 to 10000 (intrinsic viscosity [η] 0.3 to
Iodine value (IV ₁ ) and molecular weight of 4,500-10,0 of the EOR-based polymer alloy (converted from 0.6 dL / g).
The ratio (IV ₁ / IV ₂ ) of the 00 to the iodine value (IV ₂ ) of the EOR polymer alloy is usually 0.1 or less, preferably 0. The EOR polymer alloy [I] having the Mooney viscosity ML _{1 + 4} (100 ° C.) and the above iodine value ratio (IV ₁ / IV ₂ ) within the above range is excellent in kneading properties using a Banbury mixer or the like. ing. The EOR polymer alloy [I] used in the present invention is a ternary EO
It can be obtained by mixing a solution or suspension of R (A) and a solution or suspension of liquid ethylene / α-olefin, and then collecting a solid. In addition, a so-called multi-stage polymerization system in which either a ternary EOR (A) or a liquid binary EOR (B) is first obtained by polymerization, and other components are obtained by polymerization in the presence of the polymer. The EOR polymer alloy [I] of the present invention
Can be obtained.

[II] Vulcanizing Agent As the vulcanizing agent, a peroxide is basically used, but sulfur may be used in combination. This is because, in the present invention, the EOR rubber compound is a peroxide vulcanized system.

As the peroxide, dicumyl peroxide (DCP), 1,3 bis (tert-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane-3 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, 2,5-dimethyl-2,5-
Examples thereof include di (benzoylperoxy) hexane and 1,1-di (tert-butylperoxy) cyclohexane.

The peroxide is used in a proportion of 1 to 15 parts, preferably 3 to 10 parts, per 100 parts of the EOR polymer alloy [I].

When sulfur is used in combination, the sulfur is
0.1 to 100 parts of the polymer alloy [I]
1 part, preferably 0.1 to 0.5 part.

In the present invention, the vulcanizing agent is previously compounded in an unvulcanized rubber compound, but may be added immediately before vulcanization of the rubber compound.

[III] Other compounding agents In addition to the EOR-based polymer alloy [I] and the vulcanizing agent [II], the EOR-based rubber compound of the present invention may be used in the production of vulcanized rubber moldings such as EOR. Compounding agents such as carbon black (1), softener (2), and zinc white, which are more generally used, can be used as long as the object of the present invention is not impaired.

(1) The type of carbon black is not particularly limited as long as it is carbon black for rubber. Furnace carbon black such as HAF, MAF, FEF and GPF is particularly preferable.

In the EOR rubber compound according to the present invention, carbon black is generally used in the range of 40 to 120 parts based on 100 parts of the above EOR polymer alloy [I]. If the amount of carbon black is less than 40 parts, the resulting vulcanized rubber tends to have reduced hardness and strength. On the other hand, when the compounding amount of carbon black is 12
If the amount exceeds 0 parts, the obtained rubber composition tends to have low processability and poor dispersion of carbon black. In the present invention, the carbon black is present in the unvulcanized rubber composition, but may be used when vulcanizing the EOR polymer alloy.

(2) As the above-mentioned softening agent, a softening agent usually used for rubber is used, and specifically, a petroleum softening agent such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petrolatum, etc. Coal tar softeners such as coal tar and coal tar pitch; fatty oil softeners such as castor oil, linseed oil, rapeseed oil and coconut oil; sub; waxes such as beeswax, carnauba wax and lanolin; ricinoleic acid Fatty acids and fatty acid salts such as palmitic acid, barium stearate, calcium stearate and zinc laurate; and synthetic high molecular substances such as petroleum resins, atactic polypropylene, and coumarone indene resins. Among them, petroleum softeners are preferably used,
Particularly, process oil is preferably used.

The EOR rubber compound (unvulcanized compound rubber) according to the present invention is prepared, for example, by the following method. That is, the EOR-based polymer alloy and the softener were mixed with a mixer such as a Banbury mixer.
Kneaded at a temperature of ~ 170 ° C for 3 to 10 minutes, and then, using rolls such as an oven roll, add sulfur and carbon black as a vulcanizing agent, and if necessary, a vulcanization accelerator or a vulcanization aid. Mix, roll temperature 40-80 ° C
After kneading for 5 to 30 minutes, the kneaded product is extruded to prepare a ribbon-shaped or sheet-shaped compounded rubber.

The EOR rubber compound of the present invention has a composition such that the loss tangent (tan δ) of the vulcanizate is 0.20 to 0.35.

Production of Vulcanized Rubber In order to obtain a vulcanized rubber from the EOR-based rubber compound according to the present invention, the unvulcanized compounded rubber is molded into an intended elastic body and then vulcanized. .

In the case of the vulcanized adhesive type, in an unvulcanized state, it is injected between a damper mass and a pulley, molded, and then vulcanized.

[0056]

The damper pulley according to the present invention has an EOR rubber compound forming an elastic body, which is disclosed in
Certain ternary EORs described in US Pat.
A polymer based on a polymer alloy consisting of (A) and a specific liquid binary EOR (B), in which the vulcanization system is specified, and a liquid EOR rubber whose intrinsic viscosity is shifted to a higher one is used. By doing so, a remarkable action and effect can be obtained as supported by the following Examples and Comparative Examples.

That is, the damper pulley of the present invention can exhibit a stable vibration-proof performance even in a high-temperature atmosphere. In a simple press-fit type damper pulley, there is a problem in the damper mass and / or the coupling between the pulley and the elastic body. It is unlikely to occur.

[0058]

EXAMPLES In order to confirm the effects of the present invention, examples will be described together with comparative examples. The present invention is not limited to these examples.

A. The basic formulation used in the examples and comparative examples is as follows.

Peroxide vulcanized EOR compounded polymer alloy 160 parts Stearic acid 1 part Zinc white 5 parts Carbon black (FEF) 60 parts Antioxidant 2 parts Organic peroxide * 5.5 parts * DCP 40 wt% content The basic formulation used in the reference example is as follows.

Formulation of sulfur vulcanized EOR compound 160 parts Polymer alloy 1 part Stearic acid 1 part Zinc white 5 part Carbon black (FEF) 60 parts Antioxidant 2 parts Sulfur 4 parts Vulcanization accelerator 3.5 parts A rubber compound using each polymer alloy (paraffin oil-containing masterbatch or paraffin oil-free type) having the specifications shown in Table 1 was kneaded with a Banbury mixer.

As the polymer alloy, a high molecular weight component (component A) having the following specifications was used, and 100 parts of the high molecular weight component (component A) was added to the low molecular weight component (B
Component) and paraffin-based oil were used so that the total amount was 60 parts (see Table 1).

[0063] <A Component Specification> ethylene / alpha-olefin: 68/32, molecular weight distribution index _{(M W / M n):} 3.
7, intrinsic viscosity [η]: 4.0 dL / g, iodine value: 22

[0064]

[Table 1]

Using the obtained kneaded material, a test piece was prepared for each of the following tests and tested. B. Test method The test method for each polymer alloy and vulcanized rubber is as follows.

[0066] [1] Measurement of molecular weight distribution index (M _W / M _n) molecular weight distribution index (M _W / M _n) is, GPC (gel Pami instantiation chromatography) (e.g., "gel Pami instantiation chromatography" Takeuchi Author, published by Maruzen Co., Ltd.).

Using standard polystyrene of known molecular weight (monodisperse polystyrene, manufactured by Tosoh Corporation), the molecular weight M and its GPC (Gel Permeation Chromium) were measured.
The measurement graph is measured and a correlation curve between the molecular weight M and the elution volume EV (ElutionVolume) is prepared. At this time, the polystyrene concentration is set to 0.02%.

[3] Hardness Test A hardness test was performed according to JIS K 6301 (1989) (vulcanization condition: 170 ° C. × 10 minutes), and a spring hardness (JIS A hardness) was measured.

[4] Tensile test The tensile test was carried out in accordance with JIS K 6301 (1989) (vulcanization conditions: 170 ° C. × 10 minutes), and the tensile strength (T _B ), elongation (E _B ), and it was measured at 100% modulus (M _100).

[5] Dynamic viscoelasticity test The dynamic viscoelasticity test was performed using a viscoelasticity tester (D
VE-V4), measuring temperature 25 ° C, frequency 15
The dynamic shear modulus (dyn / cm ² ) and the dynamic loss modulus (dyn / cm ² ) were determined under the conditions of Hz, 100 Hz and a strain rate of 0.5% and 1.8%, and the loss tangent tan δ was obtained. (Index of vibration damping) was determined by the following equation. The vulcanization conditions were 170 ° C. × 10 minutes as in the above.

E ^* = E ′ + iE ″ tan δ = E ″ / E ′ (E ^* : dynamic complex elastic modulus, E ′: dynamic shear elastic modulus,
E ”: dynamic loss elastic modulus) [6] Heat resistance test The heat resistance test was performed under the conditions shown in JIS K6301.
(1989), heat treatment (120 ° C × 70
h) After that, the change in hardness (ΔH) and set (CS) were determined.

C. Test Results and Evaluation From Tables 2 and 3 showing the results of the above tests, when the intrinsic viscosity [η] of the liquid binary EOR is within the range of the present invention, the loss tangent (tan δ) is 0. It is clearly seen that it is as high as 20 or more and excellent in damping property (damping property).

That is, Comparative Example 1 using EOR-2 containing only a high molecular weight component and no low molecular weight component, the limiting viscosity [η]
Comparative Example 2.3 using EOR-3.4 having a molecular weight of less than 0.3 and Comparative Example 4 using EOR-7 having an intrinsic viscosity [η] of more than 0.70, and EOR- having an insufficient low molecular weight component. Comparative Example 5 using No. 10, and further, the low molecular weight component was a ternary EOR
In Comparative Example 6 using EOR-11, the loss tangent (tan δ) was less than 0.20 (see Table 3).

From Table 2, it can be seen that a damper pulley in which the elastic body of the present invention was formed of a peroxide-cured compound (Example 1)
It can be seen that, compared to the damper pulley formed of the sulfur vulcanized compound (Reference Example), the damping characteristics are not so inferior and the heat resistance is remarkably excellent.

[0075]

[Table 2]

[0076]

[Table 3]

[Brief description of the drawings]

FIG. 1 is a judgment view showing an example of a damper pulley to which the present invention is applied.

[Description of Signs] 12 Damper mass (hub) 14 Pulley 16 Elastic body 18 Damper pulley

(72) Inventor Katsumasa Takeuchi 1 Ochiai Nagahata, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Inside Toyoda Gosei Co., Ltd. (72) Inventor Hideyuki Imai 1 Nagachi Ochiai, Kasuga-cho, Nishi-Kasugai-gun, Aichi 1 Toyoda Gosei Co., Ltd. Inside the company (72) Inventor Satomi Watanabe 1 at Nagahata, Ochiai, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Inside of Toyota Kasei Co., Ltd. (72) Inventor Hidenari Nakahama 3 Chigusa Beach, Ichihara City, Chiba Prefecture Mitsui Oil Chemicals Co., Ltd.

Claims (2)

[Claims] 1. A damper pulley in which an elastic body is interposed between a damper mass and a pulley, wherein the elastic body is a peroxide vulcanizing system based on a polymer alloy satisfying the following requirements (1) to (3). A damper pulley, which is formed of a vulcanized rubber compound and has a loss tangent (tan δ) of 0.20 to 0.35. (1) The polymer alloy is an ethylene / α-olefin / non-conjugated diene copolymer rubber (A): 80 to 60% by weight
And liquid ethylene / α-olefin copolymer (B): 20
-40% by weight. (2) The ethylene / α-olefin / non-conjugated diene copolymer rubber comprises ethylene, an α-olefin having 3 to 20 carbon atoms and a non-conjugated diene, and comprises ethylene and α.
- the molar ratio of olefin is 60 / 40-73 / 27, the molecular weight distribution index (M _W / M _n) is less than 4, an intrinsic viscosity [eta] of about 2.7～5.0DL / g The iodine value is 10 to 40, and the non-conjugated diene is 5-ethylidene-2-norbornene. (3) The liquid ethylene / α-olefin copolymer rubber comprises ethylene and an α-olefin having 3 to 20 carbon atoms, and the molar ratio of ethylene to the α-olefin is 50/50 to 78 /. 22, and the intrinsic viscosity [η] is 0.3 to 0.6 dL / g. 2. The damper pulley according to claim 1, wherein the elastic body between the damper mass and the pulley is simply press-fitted.