JP2002121325A - Rubber vibration insulator composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber vibration insulator composition which improves noise generation, a riding feeling and steering stability of vehicles. SOLUTION: The rubber composition comprises, as a rubber component, natural rubber alone or a blend of natural rubber and a synthetic rubber, wherein in the dependense of dynamic viscoelastic properties on amplitude at a temperature of 23 deg.C, a frequency of 50 Hz and a tensile strain amplitude in the range of 0.01-5%, tan δ is always 0.13 or more and the rate of change of dynamic elastic modulus is less than 55% based on the maximum value of the modulus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration rubber composition which is used for an engine mount of an automobile and has improved noise performance, ride comfort and steering stability in a well-balanced manner.

[0002]

2. Description of the Related Art Anti-vibration rubbers such as engine mounts have conventionally been used to absorb vibrations of automobiles and vehicles to prevent noise.

[0003] In general, the characteristics required of the vibration-proof rubber are that the dynamic magnification (dynamic elastic modulus / static elastic modulus) is small in a high frequency region related to noise transmission during running, and the vibration-related rubber is involved in vibration transmission such as when the engine is started. In the low frequency region, the one with a large attenuation coefficient (the magnitude of the loss tangent tan δ is an index) has obtained good vibration-proof characteristics. Therefore, a rubber material having a small dynamic magnification and a large tan δ is also required as a rubber material of the vibration-proof rubber.

[0004] Vibration-proof rubber requires resistance to deformation and destruction, and rubber materials must also have sufficient toughness and durability.

Therefore, the rubber material constituting the rubber composition of the vibration damping rubber is natural rubber alone or natural rubber 50.
A certain amount of a specific end group-modified SBR or copolymer or a specific carbon black is blended in a blend system of at least part by weight and a synthetic rubber such as styrene-butadiene rubber,
Attempts have been made to improve the dynamic resistance and the tan δ and to improve the fatigue resistance, but they have not been sufficiently satisfactory. (Japanese Unexamined Patent Publication No.
134269, JP-A-10-87883, etc.) Natural rubber has a small tan δ in a low-frequency region. Therefore, by blending a large amount of carbon black, the tan δ of the rubber composition can be increased. The dynamic magnification also increases in proportion to the amount of carbon black,
At present, there is no vibration-proof rubber composition that satisfies the trade-off characteristics of dynamic magnification and tan δ based on examination of rubber materials and compounding agents.

[0006] In recent years, the performance requirements of automobile users have become severer and more sophisticated, and it has been required to improve the performance of automobiles in terms of noise performance, ride comfort, steering stability, etc., and these performance requirements are well balanced. At present, there is no vibration-proof rubber composition obtained.

[0007]

In the conventional rubber composition, in consideration of the dynamic magnification and the damping coefficient, it has been found that both the vibration damping performance in the low frequency range and the vibration damping performance in the high frequency range are compatible. There was a limit to the improvement of the vibration proof rubber that balanced the noise performance, ride comfort and steering stability.

According to the present invention, the noise performance, the riding comfort, and the steering stability of the vibration-proof rubber can be improved in a well-balanced manner by using a new improvement index for the vibration-proof performance in order to satisfy the performance required by the automobile user. It is intended to provide a rubber composition.

[0009]

Means for Solving the Problems To achieve the above object, the present inventors have conducted intensive studies and as a result, have found that a rubber composition containing a natural rubber alone or a blend of a natural rubber and a synthetic rubber as a rubber component. Focusing on the amplitude dependence of the dynamic elastic modulus of rubber, a rubber composition having a large damping property (tan δ), a small amplitude dependence of the dynamic elastic modulus, and a small change rate has a low noise performance. It was found that the ride comfort and steering stability were excellent in a well-balanced manner, and the present invention was completed.

That is, the present invention relates to a rubber composition containing a natural rubber alone or a blend of a natural rubber and a synthetic rubber as a rubber component, wherein the temperature is 23 ° C., the frequency is 50 Hz, and the tensile strain amplitude is 0.01% to 5%. Wherein the tan δ is always 0.13 or more and the rate of change of the dynamic elastic modulus is less than 55% of its maximum value in the dynamic viscoelastic characteristic amplitude dependence in the range of It is a rubber composition.

According to the rubber composition of the present invention, tan δ
By always maintaining at least 0.13, the vibration damping property is improved, the riding comfort and steering stability are improved, and the dynamic elastic modulus change rate is less than 55% of its maximum value. Noise transmission during traveling can be reduced, noise performance can be improved, and balanced vibration isolation performance of the vibration isolation rubber can be obtained in a wide frequency range.

[0012]

Embodiments of the present invention will be described below.

As the rubber component used in the rubber composition of the present invention, natural rubber (NR) alone or a blend of natural rubber and synthetic rubber is used.

NR has a low dynamic elastic modulus and is excellent in noise performance and resistance to repeated deformation, and can be used alone as a rubber component of the vibration damping rubber composition.

On the other hand, the NR has a low tan δ in a low frequency range, so that it cannot be said that the riding comfort and the steering stability are sufficient, and a blend with another synthetic rubber can be used to increase the tan δ.

Synthetic rubbers to be blended in order to maintain the noise performance and fatigue resistance of NR and improve ride comfort and driving stability include styrene butadiene rubber (SBR),
Butadiene rubber highly containing two bonds (high 1,2-B
R), a diene-based synthetic rubber such as acrylonitrile-butadiene rubber (NBR) is highly suitable because it has an effect of increasing Tan δ.

Furthermore, SBR having a vinyl group content of 60% by weight or more in the butadiene portion is preferable because the presence of the vinyl group is excellent in dispersibility with NR and has a large effect of improving tan δ.

When the blend ratio of the synthetic rubber to NR exceeds 50 parts by weight in the rubber component, the fatigue resistance due to NR decreases, and the fatigue resistance of the rubber composition as a whole decreases. Therefore, the blending amount is 100 parts by weight of NR to 50 parts by weight.
An appropriate range is 0 to 50 parts by weight of the synthetic rubber based on parts by weight.

The value of tan δ is as follows: temperature 23 ° C., frequency 50
In the dynamic viscoelastic amplitude dependency in the range of Hz and the tensile strain amplitude in the range of 0.01% to 5%, 0.13 or more is always required in the entire range of the amplitude range.

Tan δ is the phase difference δ between vibration stress and vibration strain.
And the loss tangent is expressed by the loss elastic modulus / storage elastic modulus, the one having a large value indicates high damping property, and tan δ is always 0.1.
By maintaining a value of 13 or more, stable vibration performance can be obtained.

When tan δ is less than 0.13, the vibration damping performance of the vibration-proof rubber is reduced, and the ride comfort and steering stability are reduced.

Further, SBR having a high vinyl group content in NR
Blending improves the dispersibility of carbon black in rubber, further improves the interaction between rubber molecules and carbon black particles, reduces the internal friction of rubber, and maintains the dynamic elastic modulus of NR. Is done.

If the change rate of the dynamic elastic modulus is less than 55% of the maximum value in the strain amplitude region, the vibration absorption performance is exhibited from the low frequency region to the high frequency region, and the noise performance is reduced. The effect can be increased as the rate of change is smaller.

When the rate of change of the dynamic elastic modulus exceeds 55%,
Variations occur in the vibration absorption performance from the low frequency range to the high frequency range, and the noise performance of the vibration isolating rubber particularly in the high frequency range decreases.

Therefore, the tensile strain amplitude is 0.01% or more.
The vibration-proof rubber using the rubber composition in which the tan δ at 5% is always 0.13 or more and the rate of change of the dynamic elastic modulus is less than 55% with respect to the maximum value thereof has a noise performance, a riding comfort, It is possible to improve the balanced performance of the steering stability.

(Examples) Examples of the rubber cushion composition according to the present invention will be described below.

As a rubber component, a rubber prepared by mixing SBR in a range of 20 to 60 parts by weight in order to improve tan δ and maintain a dynamic elastic modulus by using Comparative Example 1 containing only NR as a control compound. A composition was made.

The SBR preferably has a butadiene moiety having a vinyl group content of 60% by weight or more. In this embodiment, the vinyl group content is 67% by weight and the styrene content is 25% by weight.
VSL1950S25 manufactured by Bayer Co., which is a weight%, was used.

This SBR was blended with NR,
80 parts by weight of NR and 20 parts by weight of SBR, NR 60 parts by weight and 40 parts by weight of SBR in Example 2, and NR in Comparative Example 2.
A mixture of 40 parts by weight and 60 parts by weight of SBR as a rubber component was used.

As other compounding agents, those compounded in ordinary vibration-proof rubbers, the following were used as common compounding agents in this example.

Carbon black (Showa Cabot Co., Ltd.)
Shaw Black N330): 60 parts by weight Aroma oil: 5 parts by weight Zinc flower: 3 parts by weight Stearic acid: 1 part by weight Antioxidant (Nocrack 6 manufactured by Ouchi Shinko Chemical Co., Ltd.)
C): 1.5 parts by weight Wax: 2 parts by weight Sulfur: 2 parts by weight Vulcanization accelerator (Noxeller T manufactured by Ouchi Shinko Chemical Co., Ltd.)
T): 1 part by weight.

The above ingredients were mixed in a conventional manner using a 1.7 liter closed Banbury mixer to obtain a rubber composition.

This rubber composition was vulcanized at a temperature of 160 ° C. for 20 minutes using a mold for preparing a sample to prepare a cylindrical test piece having a diameter of 8 mm and a height of 4 mm. The dynamic viscoelastic properties of a tensile type, 23 ° C., frequency of 50 Hz, strain amplitude of 0.01% to 5% were measured using a Toyo Seiki Seisakusho Rheograph Solid.

The amplitude dependency of tan δ and the dynamic elastic modulus are shown in FIGS.

Then, the minimum value of tan δ and the rate of change of the dynamic elastic modulus with respect to its maximum value were calculated, and the results are shown in Table 1.

Next, a strut mount 1 for suspension shown in FIG. 3 was trial-produced using each rubber composition 2 and assembled into a domestic passenger car having a displacement of 1800 cc to obtain a noise performance.
Ride comfort and steering stability were evaluated. The results are shown in Table 1. The evaluation method is as follows.

Noise performance: In an actual vehicle running test,
This is a result of judging the road noise and muffled sound felt by the panelists in the driver's rear seat during continuous running at 00 km / h. "○" indicates that the noise performance is good, "◎" indicates that the noise performance is further excellent, and "poor". The case was evaluated as "x".

Ride comfort: In actual vehicle running test, 1
This is the result of the test driver's determination of the riding comfort of the car during continuous running at 00 km / h. The evaluation was "○" for good riding comfort, "◎" for more excellent riding comfort, and "x" for poor riding comfort. .

Driving stability: This is the result of a test driver's judgment on steering operation such as lane change during continuous driving at a speed of 100 km / h in an actual vehicle running test. An excellent case was evaluated as “◎”, and an inferior case was evaluated as “×”.

[0040]

[Table 1] In Examples 1 and 2, as shown in Table 1 and FIGS. 1 and 2, the value of tan δ was always 0.13 or more, and the rate of change of the dynamic elastic modulus was 55% of its maximum value. The noise performance, ride comfort and steering stability are well-balanced and good. Example 1 has a larger value of tan δ, and is more excellent in ride comfort and steering stability.

In Comparative Example 1, the dynamic elastic modulus change rate was less than 55% and the noise performance was good. However, as shown in FIG. 1, tan δ was small in the low to medium amplitude range, and the riding comfort and steering stability were low. Insufficient. Comparative Example 2 has a large tan δ and good ride comfort and steering stability. However, as shown in FIG. 2, the dynamic elastic modulus changes greatly and the noise performance deteriorates.

As described above, the tan δ of the rubber composition is always at least 0.13, and the rate of change of the dynamic elastic modulus is 55%.
When it is less than the above, the noise performance, the riding comfort, and the driving stability can be improved in a well-balanced manner.

[0043]

As described above, the vibration damping rubber composition of the present invention is a rubber composition containing natural rubber alone or a blend of natural rubber and synthetic rubber as a rubber component, at a temperature of 23 ° C. and a frequency of 50 Hz. , The tensile strain amplitude is 0.0
In the dynamic viscoelastic characteristic amplitude dependence in the range of 1% to 5%, tan δ is always 0.13 or more, and the rate of change of the dynamic elastic modulus is less than 55% of its maximum value. It has an excellent effect of improving the noise performance, riding comfort, and steering stability required for vibration isolation rubber in a high-order manner.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing amplitude dependency of tan δ of a rubber composition of the present invention.

FIG. 2 is a characteristic diagram showing the amplitude dependence of the dynamic elastic modulus of the rubber composition of the present invention.

FIG. 3 is a cross-sectional view of a slat mount using the rubber composition of the present invention.

[Explanation of symbols]

 1. Slat mount 2. Anti-vibration rubber composition

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Toshiya Tsujimoto 1-17-18 Edobori, Nishi-ku, Osaka-shi, Osaka F-term in Toyo Tire & Rubber Co., Ltd. 3J048 AA01 BD04 EA01 EA07 4J002 AC01W AC04X AC07X AC08X GN00

Claims (1)

[Claims] A rubber composition comprising a natural rubber alone or a blend of a natural rubber and a synthetic rubber as a rubber component,
Temperature 23 ° C., frequency 50 Hz, tensile strain amplitude of 0.
In the dynamic viscoelastic characteristic amplitude dependence in the range of 01% to 5%, it is necessary that tan δ is always 0.13 or more, and that the rate of change of the dynamic elastic modulus is less than 55% of its maximum value. An anti-vibration rubber composition characterized.