JP3806492B2 - Rubber composition for seismic isolation laminate - Google Patents

Description

【００１９】
また、高減衰ゴム支承の等価減衰定数はせん断ひずみの増加に伴って減少する傾向にあり、保有水平耐力法レベルで期待できる橋の減衰定数は0.12〜0.15が妥当である。それ故、これを満足する対象ひずみレベルでの高減衰ゴム支承に要求される等価減衰定数は0.13程度以上となる。
【００２０】
クリープ性（％）：
温度＋２０℃で、設計支圧応力度（６０kgf/cm² ）に相当する鉛直荷重を１０００時間作用させた場合に免震装置に生じる鉛直変位をもとに、式（１）から橋の設計供用年数に相当するクリープを求める。
δ_CR＝at^b (1)
ここに、
δ_CR：免震装置のクリープ変形量（mm）
t ：橋の設計供用年数（時間）
a,b ：クリープ定数で、式（２）および式（３）より算出する。
【００２１】
a ＝（δ₁₀₀ ）² ／（δ₁₀₀₀）² (2)
b ＝ log（δ₁₀₀₀／δ₁₀₀ ） (3)
δ₁₀₀ ：１００時間後に生じる免震装置の鉛直変位（mm）
δ₁₀₀₀：１０００時間後に生じる免震装置の鉛直変位（mm）
式（１）で算出した橋の設計供用年数に相当するクリープ量は、ゴム総厚の５％以下でなければならない。
【００２２】
【表２】

【００２３】
表２から明らかなように、本発明ゴム組成物（実施例１〜３）は、比較例のゴム組成物に比して高弾性率でかつ振動エネルギー吸収性に優れていることが判る。
【００２４】
【発明の効果】
以上説明したように本発明の免震積層体用ゴム組成物は、天然ゴムを主成分とするゴム１００重量部に対し、超高分子量ポリエチレン５〜３０重量部、石油樹脂１５〜６０重量部、および微粒子カーボンブラック５０〜９０重量部を含んでなるため、振動エネルギー吸収性、長期耐久性に優れるものである。
【図面の簡単な説明】
【図１】免震積層体の一例を示す断面説明図である。
【符号の説明】
１ 免震積層体 ２ ゴム組成物 ３ 硬質板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rubber composition capable of efficiently absorbing vibration energy with a high elastic modulus and excellent in long-term durability.
[0002]
[Prior art]
In recent years, vibration energy absorbing devices, that is, anti-vibration, seismic isolation, seismic isolation devices, and the like are rapidly spreading. In this apparatus, a rubber composition having a high damping property is used.
Conventionally, a large amount of carbon black or petroleum resin is blended in order to give a rubber material high damping characteristics, that is, to obtain a rubber composition having high damping characteristics.
[0003]
However, when carbon black is mixed in a large amount, the damping performance is improved (high hysteresis loss), but the scouring processability is inferior and the shear fracture characteristics of the seismic isolation device are lowered. On the other hand, even when a large amount of petroleum resin is blended, the damping characteristics are improved, but the creep characteristics are lowered and the long-term durability is inferior.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a rubber composition for a seismic isolation laminate having a high elastic modulus, excellent vibration energy absorption and long-term durability for the purpose of downsizing the apparatus.
[0005]
[Means for Solving the Problems]
The rubber composition for a seismic isolation laminate of the present invention comprises 5 to 30 parts by weight of ultra high molecular weight polyethylene, 15 to 60 parts by weight of petroleum resin, and 50 fine carbon blacks with respect to 100 parts by weight of rubber mainly composed of natural rubber. It is characterized by comprising -90 parts by weight.
[0006]
Thus, since natural rubber (NR), ultrahigh molecular weight polyethylene, petroleum resin, and fine particle carbon black are used in combination, high elastic modulus, vibration energy absorption and long-term durability can be improved.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an explanatory cross-sectional view showing an example of a seismic isolation laminate. In FIG. 1, the seismic isolation laminate 1 has a structure in which a rubber composition 2 is laminated in a plurality of layers via a rigid plate 3 having rigidity such as a steel plate.
In the present invention, as the rubber composition 2 in FIG. 1, a rubber composition comprising natural rubber (NR), ultrahigh molecular weight polyethylene, petroleum resin, and fine carbon black is used.
[0008]
As the natural rubber (NR), any commercially available rubber may be used. In addition to NR, rubbers such as isoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), and butadiene rubber (BR) may be blended.
The ultra high molecular weight polyethylene is a powder having a molecular weight (viscosity method) of 1 million or more and an average particle diameter of 15 to 50 μm, preferably 20 to 35 μm. As this ultra high molecular weight polyethylene, for example, “Mipperon” manufactured by Mitsui Petrochemical Co., Ltd. and “Suntech” manufactured by Asahi Kasei are commercially available.
[0009]
Petroleum resins include coumarone, indene, styrene, and other coumarone plastics contained in solvent naphtha, and cracked oil fractions by-produced from ethylene plants that produce ethylene, propylene, etc. by steam cracking of petroleum. Resins obtained by polymerizing the diolefins and monoolefins contained in the product without isolation, such as Exlon (manufactured by Nippon Steel Chemical Co., Ltd.), High Resin (manufactured by Toho Chemical Co., Ltd.), FTR (Mitsui Petrochemical Co., Ltd.) (Manufactured by Kogyo Co., Ltd.).
[0010]
Particulate carbon black used in the present invention are nitrogen specific surface area of usually 60~150 m ² / g, especially is 80~150 m ² / g, DBP oil absorption amount normally 60~160cm ³ / 100g, particularly 90 to The thing of 160cm < ³ > / 100g is preferable. Such products are commercially available as HAF, ISAF, and SAF type carbon blacks represented by ASTM, and can be used.
[0011]
In the present invention, 5 to 30 parts by weight of ultrahigh molecular weight polyethylene, 15 to 60 parts by weight of petroleum resin, and 50 to 90 parts by weight of fine carbon black are blended with 100 parts by weight of rubber mainly composed of NR.
If the ultrahigh molecular weight polyethylene is less than 5 parts by weight, the effect of improving the elastic modulus of the resulting rubber composition is insufficient, and if it exceeds 30 parts by weight, the rubber becomes too hard, the ability to absorb vibration energy is inferior, and the elongation decreases. Become a source of creep. If the amount of petroleum resin is less than 15 parts by weight, the ability to absorb vibration energy is insufficient, and if it exceeds 60 parts by weight, creep becomes large. If the fine particle carbon black is less than 50 parts by weight, the ability to absorb vibration energy is inferior, and if it exceeds 90 parts by weight, the processability is lowered during the production of the rubber composition of the present invention.
[0012]
In producing the rubber composition of the present invention, N-cyclohexyl-2-benzothiazolylsulfenamide, Nt-butyl-2-benzothiazolylsulfene is used for the purpose of vulcanizing unvulcanized rubber. An appropriate amount of a vulcanization accelerator such as amide and a vulcanization aid such as zinc white or stearic acid is blended in the unvulcanized rubber.
An example in which the rubber composition of the present invention is applied to a seismic isolation laminate is shown in FIG. 1, but the rubber composition 2 of the present invention and a hard plate 3 made of, for example, a general structural steel plate, a cold rolled steel plate, and the like Are stacked alternately to form a seismic isolation stack. In order to produce this laminate, after molding and vulcanizing to obtain a sheet-like rubber composition, it may be adhered to a hard plate with an adhesive, or an unvulcanized rubber compound may be preliminarily bonded. It can also be produced by forming into a sheet shape, laminating with a hard plate, and then heating to vulcanize and bond simultaneously.
[0013]
Such a seismic isolation laminate can be used, for example, for road bridges and building foundations.
[0014]
【Example】
Rubber compositions were prepared with the blending contents (parts by weight) shown in Table 2 (Examples 1 to 3, Comparative Examples 1 and 2). These rubber compositions were evaluated for tensile strength (T _B ), elongation at break (E _B ), and JIS A hardness (Hs) as follows. In addition, the seismic isolation laminate (size 135 mm x 135 mm x 74 mm) in which rubber and iron plates are alternately laminated is prepared, and the shear elastic modulus (G), equivalent damping constant (h _eq ), and creep properties (bridge The creep amount corresponding to the design service years) was evaluated. Here, G represents a shear elastic modulus, and h _eq represents an equivalent damping constant. The results are shown in Table 2.
[0015]
Tensile strength (T _B , kgf / cm ² ):
Measured according to JIS K 6301. The larger the value, the greater the strength and the harder it is to break.
Elongation at break (E _B ,% ):
Measured according to JIS K 6301.
[0016]
Shear elastic modulus (G ):
It calculated | required on the conditions at the time of 0.5 Hz and 175% distortion with the biaxial shear tester. It is sufficient 12kgf / cm ² or more.
Equivalent damping constant (h _eq ):
It calculated | required on the conditions at the time of 0.5 Hz and 175% distortion with the biaxial shear tester.
[0017]
High-damping rubber bearings used as bridge seismic isolation devices must have an energy absorption capacity during earthquakes so that the damping constant expected for the design can be obtained. In the “Seismic Isolation Design Manual for Road Bridges (Ministry of Construction (Civil Engineering) Research Center)), which is the basis for seismic isolation design, the correction coefficient for the design horizontal seismic intensity based on the bridge damping constant is as shown in Table 1 below. As a bridge, it is desired that the vibration during an earthquake be about 80% (absorbing about 20% of the energy during an earthquake).
[0018]
[Table 1]

[0019]
In addition, the equivalent damping constant of high-damping rubber bearings tends to decrease with increasing shear strain, and 0.12-0.15 is a reasonable bridge damping constant that can be expected at the possessed horizontal strength method level. Therefore, the equivalent damping constant required for the high damping rubber bearing at the target strain level that satisfies this is about 0.13 or more.
[0020]
Creep property (% ):
Based on the vertical displacement generated in the seismic isolation device when a vertical load corresponding to the design bearing stress (60kgf / cm ² ) is applied for 1000 hours at a temperature of + 20 ° C, the bridge is used for design from Equation (1). Find the creep equivalent to the number of years.
δ _CR = at ^b (1)
here,
δ _CR : Creep deformation of seismic isolation device (mm)
t: Design life of bridge (hours)
a, b: Creep constant, calculated from Equation (2) and Equation (3).
[0021]
a = (δ ₁₀₀ ) ² / (δ ₁₀₀₀ ) ² (2)
b = log (δ ₁₀₀₀ / δ ₁₀₀ ) (3)
δ ₁₀₀ : Vertical displacement of the seismic isolation device after 100 hours (mm)
δ ₁₀₀₀ : Vertical displacement of the seismic isolation device after 1000 hours (mm)
The amount of creep corresponding to the bridge design service life calculated by equation (1) must be 5% or less of the total rubber thickness.
[0022]
[Table 2]

[0023]
As is clear from Table 2, the rubber compositions of the present invention (Examples 1 to 3) are found to have a higher elastic modulus and excellent vibration energy absorption than the rubber compositions of the comparative examples.
[0024]
【The invention's effect】
As described above, the rubber composition for a seismic isolation laminate of the present invention has 5 to 30 parts by weight of ultrahigh molecular weight polyethylene, 15 to 60 parts by weight of petroleum resin, based on 100 parts by weight of rubber mainly composed of natural rubber. And 50 to 90 parts by weight of fine carbon black, it is excellent in vibration energy absorption and long-term durability.
[Brief description of the drawings]
FIG. 1 is a cross-sectional explanatory view showing an example of a seismic isolation laminate.
[Explanation of symbols]
1 Seismic isolation laminate 2 Rubber composition 3 Hard plate

Claims (2)

For seismic isolation laminate comprising 5 to 30 parts by weight of ultrahigh molecular weight polyethylene, 15 to 60 parts by weight of petroleum resin, and 50 to 90 parts by weight of fine carbon black with respect to 100 parts by weight of rubber mainly composed of natural rubber Rubber composition. The particulate carbon black is nitrogen specific surface area 60~150m ² / g, the seismic isolation laminate-body rubber composition of claim 1 having a DBP oil absorption of 60~160cm ³ / 100g.

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