JP7057684B2 - Rubber member and damper using it - Google Patents

Description

The present invention relates to a damper rubber member suitable for a damper mounted on a rotating shaft such as a crankshaft or a camshaft of a vehicle engine and absorbing the torsional vibration of the rotating shaft, and a damper using the same.

The torsional damper that transmits the rotation of the rotating shaft such as the crankshaft and camshaft of the vehicle engine to the driven equipment has a hub attached to the rotating shaft and an inertial ring arranged radially outward of the hub. However, a rubber member is interposed in the gap between the outer peripheral surface of the hub and the inner peripheral surface of the inertial ring. This rubber member plays a role of reducing the torsional vibration of the rotating shaft generated while the vehicle is running, preventing the rotating shaft from being damaged, and reducing the noise and vibration of the engine vibration.

Patent Document 1 describes oil-extended EPDM, low-viscosity EPDM having a Mooney viscosity of 10 or less, and 1.5 to 2.4 parts by weight of dicumyl peroxide or 1.0 to 1.8 parts by weight per 100 parts by weight of these EPDM components. The EPDM composition containing a part of dicumyl peroxide and 0.1 to 0.5 parts by weight of sulfur has excellent heat resistance and effectively prevents deterioration of the attenuation coefficient, strength, elongation, etc. at high temperature. Suitable for use in torsional damper molding and the like, and when such an EPDM composition is used alone with a specified amount of dicumyl peroxide, it is represented by tan δ (150 ° C./room temperature, 100 Hz). The value shows a decay coefficient of about 1.2 to 0.9, and when a specified amount of dicumyl peroxide and sulfur are used in combination, the elongation retention rate at 150 ° C. is about 60% or more. Is disclosed.

Patent Document 2 describes the inherent strength and compression set characteristics of diene-based synthetic rubber by blending diene-based synthetic rubber and EPDM and using both sulfur or sulfur compounds and organic peroxides in combination. Methods for improving ozone resistance without reducing it are disclosed. As for the blending ratio of each component, about 50 to 80 parts by weight of diene synthetic rubber, 0.1 to 2 parts by weight of sulfur per 100 parts by weight of rubber component, and sulfur compound with respect to the total amount of diene synthetic rubber and EPDM. In the case of 0.1 to 10 parts by weight, the organic peroxide is 0.2 to 4 parts by weight when the number of effective functional groups is 1, and 0.1 to 2 parts by weight when the number of functional groups is 2.

In Patent Document 3, the component fraction (fnn) of the second component measured at 150 ° C. by the Hahn echo method using pulsed NMR is 0.2 to 0.6, and is at −40 to 150 ° C. A rubber member having a loss tangent (tan δ) of 0.35 or more from a low temperature region to a high temperature region, characterized in that the loss tangent (tan δ) exceeds 0.35 and is less than 1.0, is disclosed. When carbon black is blended, the average particle size of 10 to 50 nm is 10 to 120 parts by weight with respect to 100 parts by weight of ethylene / propylene rubber.

Japanese Unexamined Patent Publication No. 2000-14395 Japanese Unexamined Patent Publication No. 63-23940 JP-A-2007-9073

The rubber member for the torsional damper is required to have not only high damping performance but also low temperature dependence of damping performance and small compression set, but in the conventional technique, improvement of damping performance and temperature dependence are required. When the compounding method of reducing the temperature is adopted, the compression set becomes worse, and it is difficult to satisfy all of them at the same time.

In Patent Document 1, although tan δ (150 ° C./room temperature, 100 Hz) shows an attenuation ratio of 1.2 to 0.9, the value of tan δ is not shown, so that high attenuation is actually achieved. It is unknown whether it is. Further, when the amount of the cross-linking agent is reduced to improve the temperature dependence of tan δ, the compression set of the rubber is deteriorated, and it is considered difficult to maintain the product performance for a long period of time. Further, the combined use of sulfur increases the retention rate of physical properties at 150 ° C., but the compression set deteriorates, and it is considered difficult to maintain the product performance for a long period of time.

In Patent Document 2, in the blending of diene rubber and EPDM, sulfur and peroxide are used in combination in order to efficiently co-crosslink EPDM, but the diene rubber has at a high temperature of 100 ° C. or higher. The badness of compression permanent distortion cannot be solved.

Patent Document 3 provides a rubber member for a damper having a tan δ of more than 0.35 and less than 1.0 at −40 ° C. to 150 ° C., which has a large tan δ. Not shown. Although there is no data on compression set, it is unlikely that the compression set is good, inferring from the amount of peroxide added.

Therefore, an object of the present invention is to provide a rubber member having high damping performance, low temperature dependence of damping performance, and small compression set, and a damper using the rubber member.

The present invention includes the following.
[1] A rubber member obtained by peroxide vulcanization of a rubber composition containing ethylene, propylene, and diene ternary copolymer (EPDM) as a main component as a rubber component.
More than 1.2 parts by weight of organic peroxide containing a dialkyl peroxide having two effective functional groups in one molecule is 4.8 parts by weight with respect to 100 parts by weight of the ethylene-propylene-diene ternary copolymer (EPDM). Peroxide of a rubber composition containing 100 parts by weight or more and 180 parts by weight or less of carbon black having less than a portion, an iodine adsorption amount of 70 mg / g to 185 mg / g, and a DBP oil absorption amount of 40 ml / 100 g to 120 ml / 100 g. A rubber member that is a vulcanized molded product.
[2] The rubber composition further contains 50 parts by weight to 80 parts by weight of the process oil with respect to 100 parts by weight of the ethylene-propylene-diene ternary copolymer (EPDM), and the polymer content of the EPDM is the rubber composition. The rubber member according to [1], which is 20% by weight or more and 40% by weight or less of an object.
[3] The organic peroxide is
2,5-dimethyl-2,5-di (tert-butylperoxy) hexane,
The rubber according to [1] or [2], which is 2,5-dimethyl-2,5-di (tert-butylperoxy) hexin-3 or 1,3-di (2-tert-butylperoxyisopropyl) benzene. Element.
[4] The loss coefficient (tanδi) at the normal operating temperature of the rubber member is 0.33 or more, and the ratio of the loss coefficient (tanδh) at the high temperature side operating temperature of the rubber member and (tanδi) at the standard operating temperature is 0. The rubber member according to [1] to [3], which is .85 or more.
[5] The rubber member according to [1] to [4], wherein the compression set (%) of the rubber member is less than 20.
[6] The rubber member according to any one of [1] to [5], wherein the rubber member has an elongation of 300% or more in accordance with JIS K6251.
[7] The rubber member according to any one of [1] to [6], wherein the rubber member has a modulus (MPa) of 1.34 to 2.88 at 100% elongation according to JIS K6253.
[8] The rubber member according to any one of [1] to [7], wherein the rubber member has a ratio of a modulus at 50% elongation to a modulus at 300% elongation of 6.7 to 10.3. ..
[9] A torsional damper having a damper hub attached to a rotating shaft and rotating integrally with the rotating shaft, and an inertial ring attached to the damper hub via a damper rubber member, wherein the damper rubber is provided. The loss coefficient (tan δ 60 ° C.) at a surface temperature of 60 ° C. of the member is 0.28 or more, and the loss coefficient (tan δ 120 ° C.) at a surface temperature of 120 ° C. of the damper rubber member is relative to the loss coefficient (tan δ 60 ° C.) at a surface temperature of 60 ° C. The torsional damper having a rubber member according to any one of [1] to [8], wherein the loss coefficient ratio (120 ° C./60 ° C. tan δ ratio) is more than 0.61 and less than 0.91.
[10] The torsional damper according to [9], wherein the damper rubber member is press-fitted between the damper hub and the inertial ring at a compressibility of 10% or more.

According to the present invention, it has high damping characteristics in a wide temperature range from room temperature to the normal operating temperature (for example, 60 ° C.) to the high temperature side operating temperature (for example, 120 ° C.), and the temperature dependence of the damping performance is small. It is possible to provide a rubber member having a small compression set, and by using such a rubber member for a damper, it is possible to maintain the damping performance and slip torque required for a torsional damper for a long period of time.

It is a perspective view which shows the torsional damper which is one Embodiment of this invention. It is a partially broken perspective view of the torsional damper shown in FIG. It is a partially broken perspective view which shows the assembly method of the torsional damper shown in FIG.

[Tortional damper]
First, as one embodiment of the present invention, the torsional damper will be described with reference to the drawings. FIG. 1 is a perspective view showing a torsional damper according to an embodiment of the present invention, and FIG. 2 is a partially broken perspective view of the torsional damper shown in FIG.

The torsional damper 10 is attached to the tip of the crankshaft of an automobile engine and is used to transmit the rotation of the crankshaft to a driven device such as an alternator or a power steering. An inertial ring 12 and an annular damper rubber member 13 are provided.

The damper hub 11 has a disc portion 11a extending in the radial direction and a boss portion 11b integrally provided in the radial center portion thereof, and the boss portion 11b is fastened to the tip of the crankshaft and is centered on the central axis C. It is driven to rotate. The damper hub 11 is typically made of cast iron such as FC250 and FCD450.

The inertial ring 12 is arranged radially outward of the damper hub 11, and a pulley groove 12a on which a belt is hung is provided on the outer peripheral surface thereof to form a pulley for power transmission. The inertial ring 12 is typically made of cast iron such as FC250.

The annular damper rubber member 13 interposed between the damper hub 11 and the inertia ring 12 has an outer peripheral surface coaxial with the central axis C of the damper hub 11 and an inner peripheral surface of the inertial ring 12 facing the outer peripheral surface. It is inserted in the gap to reduce the torsional vibration of the crankshaft that occurs while the vehicle is running, prevent damage, and reduce the noise and vibration of engine vibration.

The torsional damper 10 is formed by vulcanizing a damper rubber composition described later to produce an annular damper rubber member 13, and then, as shown in FIG. 3, the boss portion 11b of the damper hub 11 is oriented in the vertical direction. With the damper hub 11 and the inertia ring 12 placed on a support base (not shown), a gap between the outer peripheral surface of the damper hub 11 and the inner peripheral surface of the inertia ring 12 using a press-fitting jig such as a press. It is manufactured by press-fitting the damper rubber member 13 into 14. The damper manufactured in this way is called a press-fit type torsional damper.

The pressure at which the damper rubber member 13 is press-fitted into the gap 14 between the damper hub 11 and the inertial ring 12 is preferably such that the compressibility of the damper rubber member 13 is 10% or more and 50% or less. If the compressibility of the damper rubber member 13 is less than 10%, the slip torque of the torsional damper 10 may not be a desired value, and it may be difficult for power to be transmitted to the belt. Further, if the compression rate is larger than 50%, stress concentration may occur in the damper rubber member 13, and the durability may be deteriorated.

The compressibility of the damper rubber member 13 is more preferably 10% or more and less than 30%. When the compression rate is within this range, it is possible to suppress the generation of rubber wear powder due to friction with the inertial ring 12 or the damper hub 11, especially in the durability test, and it becomes easy to obtain good durability. Further, the press-fitting property of the damper rubber member is good, and it becomes easy to realize stable dimensional accuracy.

As a method for manufacturing the torsional damper 10, in addition to the above-mentioned press-fitting method, the damper rubber composition constituting the damper rubber member 13 is injected into the gap portion 14 between the damper hub 11 and the inertial ring 12 and heated by vulcanization adhesion. There is a law. A damper manufactured by the vulcanization bonding method is called a vulcanization bonding type torsional damper.

According to the vulcanization bonding method, the original characteristics of the damper rubber member are more likely to be exhibited than the press-fitting method, but it is easy to cause poor bonding, and adjustment is required to increase the bonding force with the damper hub 11 and the inertial ring 12. Will be. In the press-fitting method, the damper rubber member 13 is compressed, so that the original characteristics of the damper rubber composition are sacrificed to some extent, but there is an advantage that poor adhesion can be reduced by a simple process of press-fitting.
In carrying out the present invention, both the press-fitting method and the vulcanization bonding method can be used.

[Damper rubber member]
The damper rubber member according to the present invention is a rubber member obtained by peroxide vulcanization of a rubber composition containing ethylene propylene diene ternary copolymer (EPDM) as a main component as a rubber component, and is the ethylene propylene diene. More than 1.2 parts by weight and less than 4.8 parts by weight of organic peroxide containing dialkyl peroxide having two effective functional groups in one molecule with respect to 100 parts by weight of ternary copolymer (EPDM), iodine adsorption amount Is a peroxide vulcanized molded product of a rubber composition containing 100 parts by weight or more and 180 parts by weight or less of carbon black having a DBP oil absorption of 40 ml / 100 g to 120 ml / 100 g and 70 mg / g to 185 mg / g. .. The peroxide vulcanization molding method for the damper rubber composition is not particularly limited, and can be carried out in a desired shape (for example, cylindrical shape) by a conventional method.

It is preferable that the damper rubber member further has the following characteristics.
(1) "Hardness" measured by a method of reading within 1 second using a durometer A according to JIS K6253: 60 or more and 80 or less (2) "Tensile strength" measured according to JIS K6251 : 10 MPa or more and 20 MPa or less (3) "Elongation (%)" measured according to JIS K6251: 300% or more and less than 550% (4) "Modulus at 50% elongation" measured according to JIS K6251: 0 1.9 MPa or more and 1.7 MPa or less (5) "Modulus at 100% elongation" measured according to JIS K6251: 1.3 MPa or more and 3.0 MPa or less (6) "300% elongation measured according to JIS K6251" Modulus at time ": 6.0 MPa or more and 17.0 MPa or less (7)" Modulus at 300% elongation "/" Modulus at 50% elongation ": 6 or more and 11 or less (8) Standard measured according to JIS K6394 "Loss coefficient (tanδi)" at operating temperature: 0.33 or more and 0.44 or less (9) "Loss coefficient (tanδh)" at high temperature side operating temperature measured according to JIS K6394: 0.29 or more and 0.41 The following (10) "Loss coefficient ratio (tanδh / tanδi)": 0.85 or more and 1.0 or less (11) Compressed permanent strain rate measured at 120 ° C. for 72 hours and 25% compression in accordance with JIS K6262. (%): Less than 20

Here, the "standard operating temperature" means a standard temperature during actual use, and as a typical example, the measured temperature of the damper rubber member 13 at 60 ° C. and the damper rubber member 13 are used as the torsional damper 10. When mounted, the surface measured temperature of the damper rubber member 13 at 60 ° C. ± 5 ° C. can be mentioned.
The "high temperature side operating temperature" means a temperature assumed at the time of actual use, and as a typical example, the measured temperature of the damper rubber member 13 at 120 ° C., and the case where the damper rubber member 13 is attached to the torsional damper 10. The surface measurement temperature of the damper rubber member 13 at 120 ° C. ± 5 ° C. is mentioned.

The "loss coefficient (tan δ, also referred to as loss tangent)" is a numerical value measured from the dynamic viscoelasticity (= loss elastic modulus / storage elastic modulus) of the damper rubber member 13. The larger this value is, the higher the vibration reduction performance of the damper rubber member is.
The "loss coefficient ratio" is an index showing the temperature dependence of the loss coefficient (tan δ). The large ratio (tanδh / tanδi) of the loss coefficient (tanδi) at the standard operating temperature to the loss coefficient (tanδh) at the high temperature side operating temperature is large (close to 1) in the temperature range from the standard operating temperature to the high temperature side operating temperature. It means that the temperature dependence of the loss coefficient (tan δ) is small, in other words, the decrease of the loss coefficient (tan δ) due to the temperature change is small.

The "compressive permanent strain rate" refers to the deformation remaining in the sample after a force such as crosslinked rubber is applied to the sample to cause compression deformation and then the force is completely removed. The compression set is a test often used to measure the residual strain due to compression of a crosslinked rubber or the like used for a portion subject to compression or shearing force. After compressing the sample at a predetermined temperature for a predetermined time, the strain remaining after a predetermined time (usually 30 minutes) has passed by removing the compressive force is determined, and is defined as follows.
CS = {(t0-t1) / (t0-t2)} × 100
CS: Compressed permanent distortion rate (%)
t0: Original thickness of test piece (mm)
t1: Thickness (mm) after 30 minutes have passed since the test piece was taken out from the compression device.
t2: Thickness (mm) of the test piece with compression strain applied

[Damper rubber composition]
Next, the damper rubber composition used for manufacturing the damper rubber member according to the present invention will be described. The damper rubber composition used for manufacturing the damper rubber member includes ethylene-propylene-diene ternary copolymer (EPDM) as an elastic body, carbon black as a filler, a cross-linking agent (peroxide) as a vulcanizing agent, and optionally. In general, it contains a co-crosslinking agent and further contains various additives (process oil (mineral oil), plasticizer, zinc white, zinc stearate, anti-aging agent, etc.). In order to obtain the desired effect in the present invention, it is necessary to select and blend specific components, which will be described below.

<EPDM>
The ethylene-propylene-diene ternary copolymer (EPDM) used in the damper rubber composition according to the present invention is not particularly limited, and an appropriate one is selected from various commercially available EPDMs, and the present invention is made. Can be used for. For example, EP104E, EP35, EP65, EP33, EP98 manufactured by JSR Corporation, Esplen 505, Esplen 505A, Esplen 601F manufactured by Sumitomo Chemical Co., Ltd., EPT X-3042E manufactured by Mitsui Chemicals Co., Ltd., and the like can be mentioned. Only one type of EPDM may be used alone, or two or more types may be mixed and used.

EPDM further preferably has the following properties.
(1) Diene amount: 2% by weight or 3% by weight or more, and / or 10% by weight or 9% by weight or less (2) Oil spread amount: 120 parts by weight or less

The oil spread amount of EPDM may be 0 parts by weight, but by using the oil spread grade EPDM, the amount of process oil described later can be reduced in consideration of the amount of oil contained in the oil spread grade EPDM. Moreover, the dispersibility of EPDM itself and carbon black can be improved.

The weight ratio (%) of EPDM in the damper rubber composition is calculated by multiplying by weight of EPDM ÷ total weight of parts of damper rubber composition × 100. The weight ratio of EPDM (also referred to as polymer fraction) in the damper rubber composition is preferably 20% by weight or more and 40% by weight or less. If the weight ratio of EPDM is less than 20% by weight, the adhesiveness of the damper rubber composition may increase and the kneading processability in manufacturing may deteriorate. On the other hand, if the weight ratio of EPDM is larger than 40% by weight, the amount of carbon added may be small and the loss coefficient may be lowered.

A general-purpose rubber component other than EPDM may be blended in the rubber composition according to the present invention, but the main component of the rubber component is EPDM. Here, the main component means that it occupies the maximum amount among all the rubber components, and preferably occupies the majority.

<Carbon black>
In the present invention, carbon black having an iodine adsorption amount of 70 mg / g or more and 185 mg / g or less and a DBP (plasticizer: dibutyl phthalate) oil absorption amount of 40 ml / 100 g or more and 120 ml / 100 g or less is used. It is necessary.

Since carbon black having various properties is commercially available, an appropriate one can be selected from these according to the above conditions and used in the present invention. For example, Tokai Carbon Co., Ltd., Sisto 600 (iodine adsorption amount: 111 mg / g, DBP oil absorption amount: 75 ml / 100 g), Sisto 9 W (iodine adsorption amount: 185 mg / g, DBP oil absorption amount: 112 ml / 100 g), Sisto 3 (iodine adsorption amount: 80 mg / g, DBP oil absorption amount: 101 ml / 100 g), seed SO (iodine adsorption amount: 44 mg / g, DBP oil absorption amount: 115 ml / 100 g) and the like can be mentioned.

There is a correlation between the particle size of carbon black and the loss coefficient (tan δ) of the damper rubber member, and the smaller the particle size of carbon black, the larger the loss coefficient. In other words, the larger the iodine adsorption amount of carbon black, the smaller the particle size of carbon black, the larger the specific surface area, and the larger the loss coefficient of the damper rubber member.
In addition, the larger the amount of DBP oil absorbed, the larger the structure of carbon black and the better the conductivity. Therefore, when the damper rubber member is attached to the torsional damper, the torsional damper is prevented from being charged and the durability is improved. Can be made to.

There is a correlation between the amount of carbon black in the damper rubber composition and the loss coefficient (tan δ) of the damper rubber member, and the loss coefficient (tan δ) increases in proportion to the increase in the amount of carbon black. Therefore, it is necessary to add 100 parts by weight or more of carbon black to 100 parts by weight of EPDM to the damper rubber composition.

<Vulcanizing agent>
A peroxide, a co-crosslinking agent, or the like can be added to the damper rubber composition as a vulcanizing agent. A tough damper rubber member is formed by heating a damper rubber composition to which a vulcanizing agent is added to carry out a crosslinking reaction.

An organic peroxide containing a dialkyl peroxide having two effective functional groups in one molecule is added to the rubber composition according to the present invention. The amount added is more than 1.2 parts by weight and less than 4.8 parts by weight with respect to 100 parts by weight of EPDM. Examples of the organic peroxide containing a dialkyl peroxide having two effective functional groups in one molecule include, for example.
2,5-dimethyl-2,5-di (tert-butylperoxy) hexane,
2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3,
1,3-Di (2-tert-butylperoxyisopropyl) benzene and the like can be used, and all of them are available as commercial products. For example, Perhexa 25B manufactured by NOF CORPORATION, Perbutyl P and the like can be mentioned.

Examples of the co-crosslinking agent include
Triallyl isocyanate,
Ethylene glycol dimethacrylate,
Trimethylolpropane Trimethacrylate,
Triallyl cyanurate,
Quinone dioxime,
1,2-Polybutadiene,
Sulfur,
Bismaleimide,
Etc. can be used, and all of them are available as commercial products. For example, TAIC manufactured by Nihon Kasei Co., Ltd., Sun Ester TMP manufactured by Sanshin Chemical Industry Co., Ltd., Barnock PM manufactured by Ouchi Shinko Chemical Industry Co., Ltd., and the like can be mentioned.

<Other additives>
In addition to the above components, a well-known rubber additive (process oil (mineral oil), plasticizer, zinc flower, zinc stearate, antiaging agent, etc.) can be added to the damper rubber composition. The blending amount of the process oil is preferably 50 parts by weight or more. All of these are available as commercial products. For example, Idemitsu Kosan's Diana Process Oil PW-380 as a process oil, DOS manufactured by Daihachi Chemical Industry Co., Ltd. as a plasticizer, and Nocrack 224 and Nocrack CD manufactured by Ouchi Shinko Chemical Industry Co., Ltd. as an antiaging agent. can.

The damper rubber composition can be prepared by mixing each component by a conventional method, and then vulcanized by a conventional method such as heating. A specific method will be described in Examples.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the present invention is not limited by the following Examples and the like.

(Example 1)
<Preparation of damper rubber composition>
First, in a 3.5 liter Banbury mixer, two types of EPDM (EPDM1 (ethylene weight ratio: 66% by weight, diene content: 4.7% by weight, Mooney viscosity (ML _{1 + 4} , 100 ° C.): 37, oil spread amount) : 120 parts by weight) 50 parts by weight (weight part of EPDM alone excluding 60 parts by weight of oil spread) and EPDM2 (ethylene weight ratio: 50% by weight, diene content: 9.5% by weight, Mooney viscosity (ML _{1 + 4} ,) 100 ° C.): 47) 50 parts by weight)), and after kneading at a rotation speed of 40 rpm for 1 minute, carbon black 1 (ISAF-LS carbon, Seest 600 (manufactured by Tokai Carbon Co., Ltd.), ethylene adsorption amount: 111 mg / G, DBP oil absorption: 75 ml / 100 g) 140 parts by weight, 80 parts by weight of process oil (adjusted so that the total of 60 parts by weight of EPDM oil spread and 20 parts by weight of process oil is 80 parts by weight) , 5 parts by weight of zinc flower, 1 part by weight of zinc stearate, and 2 parts by weight of an antiaging agent were added and kneaded for 2 minutes, and after further kneading for 1 minute, the kneaded product was discharged from the Banbury mixer. Subsequently, the discharged kneaded material was wound around a 12-inch roll having a roll interval of 5 mm to form a sheet, and the formed dough was left at room temperature for 12 hours or more.

Next, the above-mentioned dough is wound around a 6-inch roll with a roll interval of 4 mm to obtain peroxide 1 as perhexa 25B (2,5-dimethyl-2,5-di (tert-butylperoxy) hexane manufactured by NOF CORPORATION). 1.8 parts by weight and 2 parts by weight of trimethylolpropane trimethacrylate as a co-crosslinking agent are kneaded, cut back 3 times each on the left and right, and then rounded 5 times, then molded into a sheet and damper rubber. The composition was obtained.

<Manufacturing of damper rubber parts>
Next, the sheet of the damper rubber composition was set in a mold, press vulcanized at 180 ° C. for 10 minutes to prepare a rubber sheet having a thickness of 2 mm, and further in a constant temperature bath at 150 ° C. for 6 hours. Heat treatment was performed to obtain a sheet-shaped damper rubber member. Further, four sheets of the damper rubber composition were stacked and set in a mold, and press vulcanization was performed at 180 ° C. for 20 minutes to prepare a disc-shaped test piece having a diameter of 29 mm and a thickness of 12.5 mm, and further 150. A disc-shaped damper rubber member was obtained by heat treatment in a constant temperature bath at ° C. for 6 hours.

<Making a press-fit type torsional damper>
An annular damper rubber member (13) having the same composition as the damper rubber member was produced and pressed into the gap between the hub (11) and the inertial ring (12) at a compression rate of 10 to 50% to obtain a torsional damper. ..

(Examples 2 to 5)
A damper rubber composition, a damper rubber member, and a torsional damper were obtained in the same manner as in Example 1 except that the amount of peroxide 1 was changed to 2.4, 3, 3.6, and 4.2 parts by weight, respectively. rice field.

(Examples 6 to 9)
A damper rubber composition, a damper rubber member, and a torsional damper were obtained in the same manner as in Example 3 except that the amounts of carbon black 1 were changed to 100, 120, 160, and 180 parts by weight, respectively.

(Examples 10 to 13)
A damper rubber composition, a damper rubber member, and a torsional damper were obtained in the same manner as in Example 3 except that the carbon black 1 was changed to the following carbon blacks 2, 3 and 4, respectively.
Carbon Black 2 (SAF carbon, Seast 9W (manufactured by Tokai Carbon Co., Ltd.), Iodine adsorption amount: 185 mg / g, DBP oil absorption amount: 112 ml / 100 g)
Carbon Black 3 (HAF Carbon Seest 3 (manufactured by Tokai Carbon Co., Ltd.), Iodine adsorption amount: 80 mg / g, DBP oil absorption amount: 101 ml / 100 g)
Carbon Black 4 (FEF Carbon Seest SO (manufactured by Tokai Carbon Co., Ltd.), Iodine adsorption amount: 44 mg / g, DBP oil absorption amount: 115 ml / 100 g)

(Comparative Examples 1 and 2)
A damper rubber composition, a damper rubber member, and a torsional damper were obtained in the same manner as in Example 1 except that the amount of peroxide 1 was changed to 1.2 to 4.8 parts by weight, respectively.

(Comparative Example 3)
A damper rubber composition, a damper rubber member, and a torsional damper were obtained in the same manner as in Example 3 except that the carbon black 1 was changed to the carbon black 5 below.
Carbon Black 5 (SRF Carbon Seest S (manufactured by Tokai Carbon Co., Ltd.), Iodine adsorption amount: 26 mg / g, DBP oil absorption amount: 68 ml / 100 g)

(Comparative Example 4)
A damper rubber composition, a damper rubber member, and a torsional damper were obtained in the same manner as in Example 3 except that the peroxide 1 was changed to the following peroxide 2.
Peroxide 2 Park Mill D (Zicmill Peroxide manufactured by NOF CORPORATION)

<Evaluation of damper rubber member>
For the evaluation described below, a disc-shaped damper rubber member was used only for compression set, and for other evaluations, test pieces were collected from the sheet-shaped damper rubber member and evaluated.

The hardness of the damper rubber member was measured in accordance with JIS K6253 by stacking three sheet-shaped damper rubber members and using a durometer A to read the damper rubber member within 1 second. The results are shown in Table 1.

Tensile strength (MPa), elongation (%) and modulus of damper rubber member (ratio of modulus at 300% elongation to modulus at 50%, 100%, 300% elongation (MPa) and modulus at 50% elongation) Was measured according to JIS K6251. As the shape of the test piece, JIS No. 5 dumbbell was used. The results are shown in Table 1.

The loss coefficient at 60 ° C. (tan δ 60 ° C.), the loss coefficient at 120 ° C. (tan δ 120 ° C.) and the ratio between them (120 ° C./60 ° C. tan δ ratio) of the damper rubber member are measured according to JIS K6394 under the following conditions. bottom. The results are shown in Table 1.
Measuring instrument: Viscoelastic analyzer YR-7130 manufactured by Ueshima Seisakusho
Deformation method: Tensile frequency: 100Hz
Amplitude: ± 1%
Preload: 480mN
Specimen shape: 20 mm (grasping interval) x 4 mm (width) x 2 mm (thickness)) strip-shaped piece

The compression set was measured using a disc-shaped damper rubber member in accordance with JIS K6262 at 120 ° C. for 72 hours under the condition of 25% compression. The results are shown in Table 1.

<Evaluation of press-fit type torsional damper>
(Evaluation of crank twist reduction effect)
Loss coefficient (tan δ 60 ° C) at the surface temperature of the damper rubber member mounted on the torsional damper at 60 ° C., loss coefficient (tan δ 120 ° C.) and loss coefficient ratio (120 ° C./60 ° C. tan δ ratio) at the surface temperature of the damper rubber member at 120 ° C. ) Was measured by the resonance sweep method (natural frequency measurement) using a high-frequency vibration tester (vibration-proof rubber torsional characteristic tester manufactured by SUM Electro Mechanics Co., Ltd.). The results are shown in Table 1. The measurement conditions are as follows.
Rubber temperature: 60 ± 5 ° C, 120 ± 5 ° C,
Vibration amplitude: ± 1.7 × 10 ^-3 rad (± 0.1 °)
Sweep speed: 100Hz / min
Based on the loss coefficient (tan δ) obtained in the above measurement, the crank twist reduction effect (the effect of reducing the twist angle of the crank shaft after mounting the damper) was evaluated by numerical calculation. Those with a tan δ of less than 0.28 are referred to as “△ (triangle)”, those with a tan δ of 0.28 or more are referred to as “○ (circle)”, and those with a tan δ of 0.31 or more are referred to as “◎ (double circle)”. bottom.

(Evaluation of durability)
The durability of the torsional damper was evaluated by using a commercially available torsional vibration tester (vibration-proof rubber torsional characteristic tester manufactured by SUM Electro Mechanics Co., Ltd.) according to the following measurement method and measurement conditions. Regarding the evaluation results, those with rubber damage before the specified number of times are marked with "x (x)", those with irregularities on the surface of the rubber part after the specified number of times are marked with "△ (triangle)", and after the specified number of times. Those with a slight amount of rubber wear powder attached were designated as "○ (circle)", and those with no abnormality in the appearance of the rubber part after the specified number of times were designated as "◎ (double circle)". The results are shown in Table 1.
<Measurement method>
-Stabilize the temperature of the damper rubber member in a constant temperature bath with an atmospheric temperature of 100 ° C.
・ With the hub fixed, twist the torsional damper left and right with a constant load to add amplitude.
<Measurement conditions>
・ Atmospheric temperature: ± 5 ℃
・ Vibration amplitude (load torque): Load torque at which the shear strain of the damper rubber member at the initial endurance is 30% or more ・ Vibration frequency: 10 Hz
・ Durability: 1 × 10 ⁷ times

(Evaluation of slip torque)
In the torsional damper, the repulsive force of compressing the rubber between the hub and the inertia ring gives the metal fittings and the rubber a constituent force. The slip torque is the maximum torque at which the metal fittings and rubber start to slide when a twisting input is applied to the damper product in the circumferential direction. Therefore, if the compression set of the damper rubber member is poor (large value), the repulsive force becomes small, so that the metal fittings and the rubber tend to slip out at an early stage, and the maximum torque (slip torque) value becomes low. ..
The slip torque measurement method and measurement conditions of the torsional damper are as follows.
<Measurement method>
Set the torsional damper on the testing machine and fix the inertia ring. A twist input is given from the hub side to measure the slip torque (slip torque) of the metal fittings and rubber. The maximum torque value of the generated torque with respect to the torsional displacement is defined as the slip torque.
<Measurement conditions>
Atmospheric temperature: Measured at 23 ± 2 ° C after leaving for a predetermined time in an environment of 120 ± 5 ° C Torsion speed: 1.4 × 10 ^-2 rad / sec (0.8 ° / s)
Torsion waveform: Triangle wave For slip torque, "◎ (double circle)" indicates that the maximum torque decrease after a predetermined time is extremely small, and "○ (circle)" indicates that the maximum torque decrease after a predetermined time elapses. , "Δ (triangle)" indicates that the maximum torque decrease after a predetermined time is slightly large, and "x (x)" indicates that the maximum torque decrease after a predetermined time elapses.

(Discussion of experimental results)
<Amount of peroxide added>
The following findings were obtained from the comparison between Examples 1 to 5 and Comparative Examples 1 and 2. That is, when the amount of peroxide added is too small (Comparative Example 1 in which 1.2 parts by weight of peroxide is added), the 120 ° C./60 ° C. tan δ ratio in the rubber member becomes large, and the temperature dependence of tan δ becomes small. However, the compression set of the rubber member incorporated in the damper deteriorates, and the product slip torque deteriorates. On the contrary, when the amount of the peroxide added is too large (Comparative Example 2 in which 4.8 parts by weight of the peroxide is added), the compression set is good, but the 120 ° C./60 ° C. tan δ ratio becomes small. The temperature dependence of tan δ becomes large.

<Number of functional groups of peroxide>
The following findings were obtained from the comparison between Example 3 and Comparative Example 4. That is, the monofunctional peroxide 2 (for example, dicumyl peroxide) has a lower cross-linking efficiency than the bifunctional peroxide 1, the compression set is deteriorated, and the product slip torque is deteriorated. Will end up. By using a dialkyl peroxide having a bifunctional group, the compression set can be further reduced and the product slip torque can be maintained for a long period of time.

<Carbon black>
From the comparison between Examples 3, 10, 11 and 12 and Comparative Example 3, it can be seen that carbon black having a large iodine adsorption amount, which indicates the specific surface area of carbon black, can improve tan δ. Further, for tan δ, it is necessary to increase the internal friction due to the interaction between the rubber component and carbon black, and between carbon black and carbon black, and carbon black having a large specific surface area has a larger interaction and a larger internal friction. , Tan δ can be improved. Further, from Examples 3, 6, 7, 8 and 9, it can be seen that the tan δ can be improved by increasing the amount of carbon black added.

Although the torsional damper, the damper rubber member, and the damper rubber composition according to the present invention have been described above, the present invention is not limited to the above, and various modifications can be made without departing from the gist thereof. For example, the torsional damper according to the present invention can be applied not only to a crankshaft but also to reduce torsional vibration in various rotating shafts such as an engine camshaft, and a pulley groove is formed on the outer peripheral surface. It can also be applied to a torsional damper having a non-type inertial ring, a torsional damper having a hub without a boss portion, and the like. Further, the rubber member according to the present invention is attached to a vibrating structure such as a handle, a vehicle body, a bracket, or an exhaust, and is a dynamic damper (dynamic vibration absorber) or noise that suppresses vibration of a specific frequency of the structure. Of course, it can also be applied to various anti-vibration rubber members for suppression.

The rubber member according to the present invention and the damper using the same have high damping characteristics in a wide temperature range from room temperature to high temperature, the temperature dependence of the damping performance is small, and the compression set is small, so that the compression set is small for a long period of time. The damping performance and slip torque can be maintained, and the industrial utility value is extremely high.

10 Tortional damper 11 Damper hub 11a Disc part 11b Boss part 12 Inertia ring 12a Pulley groove 13 Damper rubber member 14 Gap part

Claims (3)

A rubber member obtained by peroxide vulcanization of a rubber composition containing ethylene, propylene, and diene ternary copolymer (EPDM) as the main component of the rubber component.
1. An organic peroxide containing a dialkyl peroxide having two oxygen-oxygen bonds (-O-O-) in one molecule with respect to 100 parts by weight of the ethylene-propylene-diene ternary copolymer (EPDM). More than 2 parts by weight and less than 4.8 parts by weight,
Carbon black having an iodine adsorption amount of 44 mg / g to 185 mg / g and a DBP oil absorption amount of 75 ml / 100 g to 115 ml / 100 g is 100 parts by weight or more and 180 parts by weight or less .
In addition, the process oil contains 50 to 80 parts by weight and contains 50 to 80 parts by weight.
The EPDM polymer fraction, which is the ratio of the EPDM parts by weight to the total weight parts of the rubber composition, is 20% by weight or more and 40% by weight or less of the rubber composition.
A rubber member that is a peroxide vulcanized molded product of a rubber composition. The loss coefficient (tan δ60 ° C.) of the rubber member at + 60 ° C. is 0.33 or more.
The ratio (tan δ 120 ° C./tan δ 60 ° C.) of the loss coefficient (tan δ 120 ° C.) at + 60 ° C. to (tan δ 60 ° C.) of the rubber member is 0.85 or more, and
The rubber member according to claim 1, wherein the compression set (%) of the rubber member is less than 20. A damper hub that is attached to the rotating shaft and rotates integrally with the rotating shaft,
An inertial ring attached to the damper hub via a damper rubber member,
A torsional damper in which the damper rubber member is press-fitted between the damper hub and the inertial ring at a compressibility of 10% or more and 50% or less.
The loss coefficient (tan δ 60 ° C.) at a surface temperature of 60 ° C. of the damper rubber member is 0.28 or more, and the loss coefficient (tan δ 120 ° C.) at a surface temperature of 120 ° C. and the loss coefficient (tan δ 120 ° C.) at a surface temperature of 60 ° C. The torsional damper having a rubber member according to claim 1 or 2, wherein the ratio ((tan δ 120 ° C.) / (tan δ 60 ° C.)) to tan δ 60 ° C.) is 0.63 or more and 0.68 or less.

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