Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-07-21
2001-01-30
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S496000, C524S552000
Reexamination Certificate
active
06180711
ABSTRACT:
TECHNICAL FIELD
This invention relates to a rubber composition for seismic isolation laminate which exhibits excellent damping capacity as well as sufficient hardening properties.
BACKGROUND ART
Seismic energy absorption systems, namely, seismic resistant systems, seismic resisting systems, and seismic isolation systems have recently come into widespread use, and seismic isolation rubber systems comprising alternately laminated rubber composition and rigid plates are used for bridge bearings and building base isolation. The seismic isolation rubber system is a system wherein the alternately laminated rubber composition and rigid plates exhibit reduced shear rigidity by being very hard in the vertical direction and flexible in the horizontal direction. Such seismic isolation rubber system functions to displace the vibration cycle intrinsic to the building from the seismic cycle to thereby remarkably reduce the acceleration applied to the building in the earthquake. The rubber composition used for such purpose is required to have high damping capacity so that the vibration is converted into heat to thereby damp the seismic energy.
In conventional rubber compositions, such high damping capacity has been realized by increasing the amount of carbon black blended or by blending a resin component. However, it has been difficult to simultaneously realize the high damping capacity and other physical properties required, and such attempt has been associated with the problem of hardening.
The present invention has been completed in view of the situation as described above, and an object of the present invention is to provide a rubber composition which offers the high damping capacity wherever it is used.
SUMMARY OF THE INVENTION
The inventors of the present invention have made an intensive study to solve the problems as described above, and found that a high damping capacity can be realized without adversely affecting other essential properties and the hardening properties can be simultaneously improved if a carbon black having predetermined carbon black properties is blended in the rubber composition. The present invention has been completed on the bases of such finding.
Furthermore, the inventors of the present invention have found that the relation between the damping capacity and the particle size and the amount blended of the carbon black required for realizing the desired high damping capacity can be represented by a certain expression. Production of a preferable rubber composition was then enabled by limiting the amount of the carbon black blended on the bases of the value calculated by such equation.
According to the present invention, there is provided a rubber composition for a seismic isolation laminate comprising at least a diene rubber; and 40 to 160 parts by weight of carbon black having a CTAB specific surface area of 120 to 370 (m
2
/g) and a CTAB specific surface area (m
2
/g)/iodine adsorption (mg/g) of up to 1.0 per 100 parts by weight of the diene rubber.
The rubber composition is preferably a rubber composition for a seismic isolation laminate characterized in that the rubber composition has a CF value in the range of 2.4 to 10.5 when the CF value is calculated by the following formula (1):
CF
=
&AutoLeftMatch;
(
Dst
)
1.1
×
(
24
M4DBP
oil
absorption
number
)
0.4
&AutoRightMatch;
(
volume
fraction
of
carbon
black
in
the
rubber
composition
)
3
×
10
4
wherein Dst is Stokes equivalent diameter (nm) of carbon black aggregates of the maximum frequency in centrifugal precipitation; 24M4DBP oil absorption number (dibutyl phthalate absorption number of compressed sample) (ml/100 g) represent the degree of primary structure development of the carbon black; and the carbon volume fraction in the rubber composition is (volume of the carbon)/(volume of the rubber composition).
REFERENCES:
patent: 3663350 (1972-05-01), Stokes
patent: 5182888 (1993-02-01), Miyamoto et al.
patent: 6107389 (2000-08-01), Oishi et al.
patent: 10110063 (1998-04-01), None
patent: 10110064 (1998-04-01), None
patent: WO98/32794 (1998-07-01), None
Oishi Hideyuki
Shimada Jun
Shirokawa Takashi
Acquah Samuel A.
Finnergan Henderson, Farabow, Garrett, Dunner, L.L.P.
The Yokohama Rubber Co. Ltd.
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