JP2015160903A - High attenuation composition, earthquake-proof damper, and aseismic base isolation bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a novel high attenuation composition that has high attenuation performance and is capable of forming a high attenuation member whose elastic modulus deterioration after being subjected to a large deformation is as small as possible; and an earthquake-proof damper and an aseismic base isolation bearing, such as architectural structures, which include a viscoelastic body formed using the high attenuation composition as a formation material.SOLUTION: A high attenuation composition contains a diene rubber having sulfur crosslinking property, not more than 50 pts.mass of an ethylene propylene binary copolymer rubber not having sulfur crosslinking property with respect to 100 pts.mass of the diene rubber, and only a crosslinking ingredient of a sulfur crosslinking system as a crosslinking ingredient. Each of an earthquake-proof damper and an aseismic base isolation bearing includes a viscoelastic body composed of the high attenuation composition.

Description

  The present invention includes a high damping composition that is a base of a high damping member for relaxing or absorbing the transmission of vibration energy, and a viscoelastic body as a high damping member made of the high damping composition. It relates to seismic dampers and seismic isolation bearings.

For example, high-attenuation members are used in a wide range of fields such as buildings such as buildings and bridges, industrial machines, airplanes, automobiles, railway vehicles, computers and peripheral equipment, household electrical equipment, and automobile tires. By using a high damping member, transmission of vibration energy can be reduced or absorbed, that is, seismic isolation, vibration control, vibration control, vibration isolation, and the like can be performed.
High damping members include a base polymer such as rubber to increase damping performance by increasing the hysteresis loss when vibration is applied, that is, to reduce the vibration energy as quickly and efficiently as possible. Generally, it is formed by a high attenuation composition adjusted so that the peak of tan δ falls within the operating temperature range of the high attenuation member.

The high attenuation composition is formed into a predetermined three-dimensional shape, and when the base polymer is rubber, the high attenuation member is formed by crosslinking.
Diene rubber is preferably used as the base polymer. Diene rubber does not have a glass transition temperature near room temperature (2 to 35 ° C), so the temperature dependence such as rigidity in the vicinity of the above room temperature, which is the most common operating temperature range, is reduced, and in a wide temperature range. There is an advantage that a high damping member showing stable characteristics can be formed.

High damping composition prepared by adding silica and silane compound (silylating agent) as damping properties to base polymer such as diene rubber, kneading and reacting silica and silane compound, etc. Is known (see Patent Document 1).
However, such a conventional high damping composition cannot sufficiently enhance the damping performance of the high damping member.

In order to further improve the damping performance of the high damping member, it may be possible to further increase the blending ratio of silica, but the high damping composition blended with a large amount of silica increases the viscosity during kneading. Workability is reduced. And in order to manufacture a high attenuation | damping member, the problem that it is not easy to knead | mix a high attenuation | damping composition or to shape | mold into a desired solid shape arises.
Therefore, in addition to silica, adding liquid rubber as a component that lowers the stiffness of the base polymer and lowers the viscosity during kneading of the high damping composition, gives good workability to the high damping composition. (See, for example, Patent Documents 2 and 3).

However, basically, all of the high damping members formed using these conventional high damping compositions containing silica as a filler have a so-called Malins effect (Mullins effect) that greatly reduces the elastic modulus after large deformation. 'effect) is likely to occur, and after a large deformation, the desired performance as a high damping member cannot be fully exhibited, and various problems may occur.
For example, if a large amount of deformation is applied to the viscoelastic body of a damping damper or seismic isolation bearing that is used as a high damping member for seismic isolation or seismic control of the building, the elastic modulus decreases greatly after that. There is a risk that it will not be possible to reliably prevent energy, such as the main shock and aftershocks following the, from being transmitted to the building. For this reason, there is a problem that the design of the damping damper and the seismic isolation bearing is complicated in order to ensure the desired performance after taking into account the decrease in the elastic modulus.

JP 7-41603 A JP 2009-30016 A JP 2011-68850 A JP 2006-52281 A

  An object of the present invention is to provide a novel high damping composition capable of forming a high damping member that has a high damping performance and also has a small decrease in elastic modulus after a large deformation is applied, and such a high damping composition. An object of the present invention is to provide seismic dampers and seismic isolation bearings for buildings having viscoelastic bodies formed as materials.

The present invention relates to a diene rubber having sulfur crosslinkability, an ethylene propylene binary copolymer rubber (EPM) having no sulfur crosslinkability of not more than 50 parts by mass per 100 parts by mass of the diene rubber, and a sulfur crosslinker as a crosslinking component. It is a highly attenuated composition containing only a crosslinking component.
Moreover, this invention is a damping damper provided with the viscoelastic body which consists of a high damping composition of the said invention, and a seismic isolation bearing.

When the high damping composition of the present invention is used to form a high damping member into a predetermined three-dimensional shape and heated, the EPM is not cross-linked and is not reacted and has a high viscosity state due to the sulfur cross-linking component. While maintaining the above, only the diene rubber can be selectively crosslinked, and a high viscosity can be imparted to the highly attenuated member after crosslinking by the function of the unreacted EPM.
Therefore, based on the synergistic effect of the rubber elasticity of the crosslinked diene rubber and the high viscosity of the unreacted EPM, it has high damping performance, and the decrease in elastic modulus after large deformation is as small as possible. It becomes possible to form a high damping member such as a vibration damper or a viscoelastic body for a seismic isolation bearing.

In the present invention, the EPM blending ratio is limited to 50 parts by mass or less per 100 parts by mass of the diene rubber for the following reason.
That is, when the blending ratio of the EPM exceeds this range, the ratio of the diene rubber is relatively reduced, and the rubber elasticity due to the crosslinked product of the diene rubber cannot be sufficiently obtained. The damping performance is lowered, and the elastic modulus is lowered greatly after a large deformation is applied.

On the other hand, by setting the blending ratio of the EPM within the above range, the effect of improving the viscosity of the high damping member by the EPM and the rubber elasticity by the crosslinked product of the diene rubber are balanced, and high damping performance. In addition, it is possible to form a highly attenuating member in which the decrease in elastic modulus after large deformation is applied is as small as possible.
Patent Document 4 describes a highly attenuated composition containing EPM and / or EPDM as a rubber component. Further, it is also described that a diene rubber such as natural rubber, styrene butadiene rubber and butadiene rubber can be used in combination as the rubber component.

  However, the crosslinking component of the system containing EPM is limited to the peroxide crosslinking system, and the EPM is used in combination with the diene rubber, and only the diene rubber is crosslinked by the sulfur crosslinking system crosslinking component. Patent Document 4 does not describe at all that a high-attenuation member that exhibits the above effect can be formed.

It is a disassembled perspective view which decomposes | disassembles and shows the test body as a model of the high attenuation member produced in order to evaluate the attenuation performance of the high attenuation member which consists of the high attenuation composition of the Example of this invention, and a comparative example. FIGS. 7A and 7B are diagrams for explaining the outline of a testing machine for displacing the test body of FIG. 1 and obtaining the relationship between the displacement and the load. It is a graph which shows an example of the hysteresis loop which shows the relationship between the displacement amount and a load calculated | required by displacing a test body using the testing machine of FIG.

<< High damping composition >>
The high-damping composition of the present invention comprises a diene rubber having sulfur crosslinkability, an ethylene propylene binary copolymer rubber having no sulfur crosslinkability of not more than 50 parts by mass per 100 parts by mass of the diene rubber, and sulfur crosslinking as a crosslinking component. It contains only the crosslinking component of the system.
<Diene rubber>
As the diene rubber, any of various diene rubbers having sulfur crosslinkability such as natural rubber, styrene butadiene rubber, isoprene rubber, butadiene rubber, chloroprene rubber, and acrylonitrile butadiene rubber can be used. Of these, natural rubber and / or polyisoprene rubber are preferable, and natural rubber having an advantage that it is easily available and a highly-damping composition can be produced at low cost is preferable.

<EPM>
Examples of the EPM include various EPMs which are binary copolymer rubbers of ethylene and propylene and have no sulfur crosslinkability because they have no unsaturated bond in the molecule.
(Mixing ratio)
The blending ratio of EPM needs to be 50 parts by mass or less per 100 parts by mass of the diene rubber.

When the blending ratio of the EPM exceeds this range, the ratio of the diene rubber is relatively small, and the rubber elasticity due to the crosslinked product of the diene rubber cannot be sufficiently obtained. The performance decreases, and the decrease in the elastic modulus after a large deformation is applied increases.
On the other hand, by setting the blending ratio of the EPM within the above range, the effect of improving the viscosity of the high damping member by the EPM and the rubber elasticity by the crosslinked product of the diene rubber are balanced, and high damping performance. In addition, it is possible to form a highly attenuating member in which the decrease in elastic modulus after large deformation is applied is as small as possible.

The blending ratio of EPM is preferably 10 parts by mass or more, particularly 15 parts by mass or more per 100 parts by mass of the diene rubber even in the above range.
If the blending ratio of the EPM is less than this range, the effect of improving the viscosity of the high damping member by blending the EPM cannot be sufficiently obtained, so that the damping performance of the high damping member is reduced or large deformation is added. There is a possibility that the decrease in the elastic modulus after being applied becomes large.

<Crosslinking component>
As described above, the crosslinking component is limited to a sulfur crosslinking component capable of selectively crosslinking only the diene rubber without crosslinking the EPM.
Examples of the sulfur-vulcanized crosslinking component include a combination of a vulcanizing agent, an accelerator, and an accelerator aid. In particular, it is preferable to combine a vulcanizing agent, a promoter, and a promoter aid that are unlikely to cause the problem that the rubber elasticity of the high damping member increases and the damping performance decreases.

Among these, examples of the vulcanizing agent include sulfur and sulfur-containing organic compounds. In particular, sulfur is preferable.
Examples of the accelerator include sulfenamide accelerators and thiuram accelerators. It is preferable to use two or more accelerators in combination because the mechanism of vulcanization acceleration varies depending on the type.

Among these, examples of the sulfenamide-based accelerator include Noxeller (registered trademark) NS [N-tert-butyl-2-benzothiazolylsulfenamide] manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Examples of the thiuram accelerator include Noxeller TBT [tetrabutylthiuram disulfide] manufactured by Ouchi Shinsei Chemical Co., Ltd.
Examples of the promoter aid include zinc oxide and stearic acid. Usually, it is preferable to use both of them as an auxiliary promoter.

The blending ratio of the vulcanizing agent, the accelerator, and the accelerator aid is not particularly limited, and may be adjusted as appropriate according to the attenuation performance and physical properties that vary depending on the use of the high attenuation member.
However, the blending ratio of the vulcanizing agent is preferably 0.5 parts by mass or more per 100 parts by mass of the diene rubber, and is preferably 3 parts by mass or less.
In addition, the blending ratio of the sulfenamide accelerator is preferably 0.5 parts by mass or more and preferably 3 parts by mass or less per 100 parts by mass of the diene rubber.

The blending ratio of the thiuram accelerator is preferably 0.5 parts by mass or more and preferably 3 parts by mass or less per 100 parts by mass of the diene rubber.
The blending ratio of zinc oxide is preferably 1 part by mass or more and preferably 5 parts by mass or less per 100 parts by mass of the diene rubber.
Furthermore, the blending ratio of stearic acid is preferably 1 part by mass or more and preferably 3 parts by mass or less per 100 parts by mass of the diene rubber.

<Other ingredients>
In the high attenuation composition of the present invention, in addition to each of the above components, various additives such as an inorganic filler such as silica, a silane compound, a softener, a tackifier, and an anti-aging agent are added at an appropriate ratio. You may mix | blend.
(silica)
As the silica, any of wet process silica and dry process silica classified by the production method may be used. In addition, it is preferable to use silica having a BET specific surface area of 100 to 400 m ² / g, particularly 200 to 250 m ² / g in consideration of further improving the effect of improving the damping performance of the high damping member. The BET specific surface area is expressed by a value measured by a gas phase adsorption method using nitrogen gas as an adsorbed gas, for example, using a rapid surface area measuring device SA-1000 manufactured by Shibata Chemical Instruments Co., Ltd.

Examples of the silica include NipSil (nip seal) KQ manufactured by Tosoh Silica Co., Ltd.
The blending ratio of silica is preferably 90 parts by mass or more and preferably 150 parts by mass or less per 100 parts by mass of the diene rubber.
If the blending ratio of silica is less than this range, there is a possibility that good damping performance cannot be imparted to the high damping member.

In addition, when the blending ratio of silica exceeds the above range, the workability of the high attenuation composition is reduced, or the durability when the high attenuation member is repeatedly largely deformed is reduced, and the high attenuation member is damaged. There is a risk of causing problems.
On the other hand, by making the blending ratio of silica in the above range, it is possible to improve durability when repeatedly deforming the high attenuation member repeatedly while giving the high attenuation member as good attenuation performance as possible. As good workability as possible can be imparted to the damping composition.

(Inorganic filler)
Examples of inorganic fillers other than silica include carbon black.
As the carbon black, one or more carbon blacks that can function as a filler can be used among various carbon blacks classified according to the production method thereof.

The blending ratio of carbon black is preferably 1 part by mass or more and preferably 5 parts by mass or less per 100 parts by mass of the diene rubber.
(Silane compound)
As the silane compound, the formula (a):

[Wherein, at least one of R ¹ , R ² , R ³ , and R ⁴ represents an alkoxy group. However, R ¹ , R ² , R ³ , and R ⁴ are not simultaneously an alkoxy group, and the other represents an alkyl group or an aryl group. ]
And various silane compounds that can function as a silica dispersant, such as a silane coupling agent and a silylating agent.

In particular, alkoxysilanes such as hexyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, and diphenyldimethoxysilane are preferred.
The blending ratio of the silane compound is not particularly limited, but it is preferably 5 parts by mass or more and preferably 25 parts by mass or less per 100 parts by mass of silica.
(Softener)
The softening agent is a component for further improving the workability of the highly attenuated composition, and examples of the softening agent include liquid rubber that exhibits a liquid state at room temperature (2 to 35 ° C.). Examples of the liquid rubber include one or more of liquid polyisoprene rubber, liquid nitrile rubber (liquid NBR), liquid styrene butadiene rubber (liquid SBR), and the like.

Of these, liquid polyisoprene rubber is preferred. Examples of the liquid polyisoprene rubber include Kuraray (trademark) LIR-30 (number average molecular weight: 28000) and LIR-50 (number average molecular weight: 54000) manufactured by Kuraray Co., Ltd.
The blending ratio of the liquid polyisoprene rubber is preferably 5 parts by mass or more per 100 parts by mass of the diene rubber, and is preferably 50 parts by mass or less.

When the blending ratio is less than this range, there is a possibility that the effect of reducing the rigidity of the high damping member by blending the liquid polyisoprene rubber cannot be sufficiently obtained. On the other hand, when the blending ratio of the liquid polyisoprene rubber exceeds the above range, the damping performance of the high damping member may be lowered.
Examples of other softening agents include coumarone indene resin.

Examples of the coumarone indene resin include various coumarone indene resins that are mainly composed of a polymer of coumarone and indene, have a relatively low molecular weight of about 1000 or less in average molecular weight, and can function as a softening agent.
As the coumarone indene resin, for example, Knit Resin (registered trademark) Coumarone G-90 manufactured by Nikkiso Chemical Co., Ltd. [average molecular weight: 770, softening point: 90 ° C., acid value: 1.0 KOHmg / g or less, hydroxyl value] : 25 KOH mg / g, bromine number 9 g / 100 g], G-100N [average molecular weight: 730, softening point: 100 ° C., acid value: 1.0 KOH mg / g or less, hydroxyl value: 25 KOH mg / g, bromine number 11 g / 100 g] V-120 [average molecular weight: 960, softening point: 120 ° C., acid value: 1.0 KOH mg / g or less, hydroxyl value: 30 KOH mg / g, bromine value 6 g / 100 g], V-120S [average molecular weight: 950, softening Point: 120 ° C., acid value: 1.0 KOH mg / g or less, hydroxyl value: 30 KOH mg / g, bromine value 7 g / 100 g] and the like.

The blending ratio of the coumarone indene resin is not particularly limited, but it is preferably 3 parts by mass or more and preferably 20 parts by mass or less per 100 parts by mass of the diene rubber.
(Tackifier)
Examples of the tackifier include petroleum resins. As the petroleum resin, for example, Marcaretz (registered trademark) M890A [dicyclopentadiene-based petroleum resin, softening point: 105 ° C.] manufactured by Maruzen Petrochemical Co., Ltd. is preferable.

The blending ratio of the petroleum resin is not particularly limited, but it is preferably 3 parts by mass or more and preferably 30 parts by mass or less per 100 parts by mass of the diene rubber.
(Anti-aging agent)
As an anti-aging agent, 1 type, or 2 or more types of various anti-aging agents, such as a benzimidazole type, a quinone type, a polyphenol type, and an amine type, are mentioned, for example. In particular, it is preferable to use a benzimidazole antioxidant and a quinone antioxidant together.

Among them, examples of the benzimidazole-based anti-aging agent include NOCRACK (registered trademark) MB [2-mercaptobenzimidazole] manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Examples of the quinone anti-aging agent include Antigen FR [aromatic ketone-amine condensate] manufactured by Cobblestone Chemical Co., Ltd.
The blending ratio of both anti-aging agents is not particularly limited, but the benzimidazole type anti-aging agent is preferably 0.5 parts by mass or more and preferably 5 parts by mass or less per 100 parts by mass of the diene rubber. The quinone anti-aging agent is preferably 0.5 parts by mass or more, preferably 5 parts by mass or less, per 100 parts by mass of the diene rubber.

  Examples of the high-damping member that can be manufactured using the high-damping composition of the present invention include seismic isolation bearings incorporated into the foundations of buildings such as buildings, and vibration control (vibration damping) incorporated into the structure of buildings. ) Seismic dampers, cable damping members such as suspension bridges and cable-stayed bridges, anti-vibration members for industrial machines, aircraft, automobiles, railway vehicles, etc., computers, peripheral equipment, and household electrical equipment Examples thereof include a vibration member, and a tread of an automobile tire.

According to the present invention, by adjusting the diene rubber, EPM, sulfur cross-linking component and other various component types, their combinations and blending ratios, the high-damping member having excellent damping performance suitable for each application Can be obtained.
<Seismic damper>
In particular, when the viscoelastic body of a vibration control damper incorporated in the structure of a building is formed using the high damping composition of the present invention as a forming material, the viscoelastic body has a high damping performance, so that Even if the damping performance of a damping damper including a viscoelastic body is improved and the whole is downsized or the number incorporated in one building is reduced, the damping performance equivalent to or higher than that of the conventional one can be obtained. Can do.

In addition, since the diene rubber can reduce the temperature dependence of the damping performance and physical properties of the viscoelastic body as described above, for example, a damping damper can be installed near the outer wall of a building having a large temperature difference. .
Therefore, according to this invention, the freedom degree of the design of the damping performance by a damping damper in a building etc. can also be expanded.

<Seismic isolation support>
In addition, when the viscoelastic body of a base isolation bearing for base isolation incorporated in the foundation of a building is formed using the high damping composition of the present invention and a forming material, the viscoelastic body also has a high damping performance. Therefore, even if the damping performance of a seismic isolation bearing including such a viscoelastic body is improved and the whole is downsized or the number incorporated in one building is reduced, the seismic isolation equivalent to or higher than the conventional one Performance can be obtained.

<Example 1>
(Preparation of highly attenuated composition)
100 parts by mass of natural rubber (SMR (Standard Malaysian Rubber) -CV60) as a diene rubber, 15 parts by mass of EPM [Mitsui EPT 0045 manufactured by Mitsui Chemicals, Inc., ethylene content: 51% by mass], and the following Table 1 Were mixed with each other and kneaded using a closed kneader to prepare a highly attenuated composition. In addition, the mass part in Table 1 is a mass part per 100 mass parts of natural rubber as a diene rubber, respectively.

Each component in the table is as follows.
Silica: NipSil (Nip Seal) KQ manufactured by Tosoh Silica Corporation
Silane compound: Phenyltriethoxysilane, KBE-103 manufactured by Shin-Etsu Chemical Co., Ltd.
Carbon Black: Dia Black (registered trademark) G manufactured by Mitsubishi Chemical Corporation
Benzimidazole anti-aging agent: 2-mercaptobenzimidazole, NOCRACK MB manufactured by Ouchi Shinsei Chemical Co., Ltd.
Quinone anti-aging agent: Antigen FR manufactured by Maruishi Chemical Co., Ltd.
Two types of zinc oxide: manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: "Tsubaki" manufactured by NOF Corporation
Coumarone resin: softening point 90 ° C., Nikko Chemical Co., Ltd. Escron (registered trademark) G-90
Dicyclopentadiene-based petroleum resin: softening point 105 ° C., Marukaretsu (registered trademark) M890A manufactured by Maruzen Petrochemical Co., Ltd.
5% oil-treated powder sulfur: vulcanizing agent, manufactured by Tsurumi Chemical Industry Co., Ltd. Sulfenamide vulcanization accelerator: N-tert-butyl-2-benzothiazolylsulfenamide, Ouchi Shinsei Chemical Industry Co., Ltd. Noxeller (registered trademark) NS
Thiuram-based vulcanization accelerator: Tetrabutylthiuram disulfide, Noxeller TBT-N manufactured by Ouchi Shinsei Chemical Co., Ltd.
<Examples 2 and 3>
A highly attenuated composition was prepared in the same manner as in Example 1 except that the blending ratio of EPM was 10 parts by mass (Example 2) and 50 parts by mass (Example 3) per 100 parts by mass of natural rubber.

<Comparative example 1>
A highly attenuated composition was prepared in the same manner as in Example 1 except that EPM was not blended.
<Comparative example 2>
A highly attenuated composition was prepared in the same manner as in Example 1 except that the blending ratio of EPM was 60 parts by mass per 100 parts by mass of natural rubber.

<Attenuation characteristic test>
(Preparation of test specimen)
The high attenuation compositions prepared in Examples and Comparative Examples were extruded into sheets and then punched to produce a disk 1 (thickness 5 mm × diameter 25 mm), as shown in FIG. Further, a highly attenuating composition in which a rectangular plate-shaped steel plate 2 having a thickness of 6 mm, a length of 44 mm, and a width of 44 mm is stacked on each other through a vulcanizing adhesive and heated to 150 ° C. while pressing in the laminating direction to form the disk 1. And the disc 1 was vulcanized and bonded to the two steel plates 2 to produce a specimen 3 for evaluating damping characteristics as a model of a high damping member.

(Displacement test)
As shown in FIG. 2 (a), two test bodies 3 are prepared, and the two test bodies 3 are fixed to one central fixing jig 4 with bolts via one steel plate 2. The left and right fixing jigs 5 were fixed to the other steel plate 2 of each test body 3 with bolts. The center fixing jig 4 is fixed to the upper fixing arm 6 of the testing machine (not shown) with a bolt via a joint 7, and the two left and right fixing jigs 5 are moved to the lower movable plate of the testing machine. 8 was fixed with bolts through a joint 9.

  Next, in this state, the movable platen 8 is displaced so as to be pushed up in the direction of the fixed arm 6 as indicated by a white arrow in the drawing, and the disk 1 is moved in the thickness direction as shown in FIG. As shown in FIG. 2 (a), a state is obtained in which the strain is deformed in the orthogonal direction, and from this state, the movable platen 8 is displaced so as to be pulled down in the direction opposite to the direction of the fixed arm 6 as indicated by a white arrow. Hysteresis loop H indicating the relationship between the displacement (mm) in the thickness direction of the disk 1 and the load (N) when the disk 1 is repeatedly subjected to strain deformation, that is, when the operation of returning to the state shown in FIG. (See FIG. 3).

In the measurement, the above operation was carried out for 3 cycles under an environment of a temperature of 20 ° C., and a third value was obtained. The maximum amount of displacement was set so that the deviation of the two steel plates 2 sandwiching the disc 1 in the direction perpendicular to the thickness direction of the disc 1 was 100% of the thickness of the disc 1.
Then, connecting the maximum displacement point and the minimum displacement point of the hysteresis loop H shown in FIG. 3 obtained by the above measurement, determine the slope Keq (N / mm) of the straight line L ₁ shown by a thick solid line in the figure, From the inclination Keq (N / mm), the thickness T (mm) of the disc 1, and the cross-sectional area A (mm ² ) of the disc 1, the formula (1):

The equivalent shear modulus Geq (N / mm ² ) was determined by Then, the relative value of the equivalent shear elastic modulus Geq (N / mm ² ) of each example when the equivalent shear elastic modulus Geq (N / mm ² ) in Comparative Example 1 was set to 100 was obtained.
Also, the absorbed energy amount ΔW represented by the total surface area of the hysteresis loop H shown with diagonal lines in FIG. 3, the straight line L ₁ shown with a mesh line in FIG. From the axis and the elastic strain energy W represented by the surface area of the region surrounded by the perpendicular L ₂ drawn from the intersection of the straight line L ₁ and the hysteresis loop H to the horizontal axis, the formula (2):

Thus, an equivalent damping constant Heq was obtained. It can be determined that the greater the equivalent damping constant Heq is, the better the specimen 3 is in damping performance. Accordingly, when the equivalent attenuation constant Heq in Comparative Example 1 is set to 100, the relative value of the equivalent attenuation constant Heq in each example is obtained, and those having a relative value less than 102 are poor, those having 102 or more are good, and those having 105 or more are good. Were evaluated as particularly good.
(Measurement of elastic modulus after large deformation)
After the above measurement, after standing for a certain period of time, the equivalent shear elastic modulus Geq (N / mm ² ) at the same deviation amount of 100% was determined. Immediately thereafter, a large deformation with a deviation amount of 300% was repeated three cycles, and then again. The equivalent shear modulus Geq ′ (N / mm ² ) at a deviation amount of 100% was determined. And equation (3):

Thus, the retention rate (%) of the elastic modulus after large deformation was obtained. It can be determined that the lower the elastic modulus after the large deformation is applied, the smaller the retention rate is. Therefore, when the retention rate in Comparative Example 1 is set to 100, the relative value of the retention rate of each example is obtained, and when the relative value is less than 102, the relative value is poor, the 102 or higher is good, and the 105 or higher is particularly Evaluated as good.
The results are shown in Table 2.

From the results of Examples 1 to 3 and Comparative Example 1 in Table 2, EPM is added to natural rubber as a diene rubber, and only the diene rubber is selectively crosslinked by a sulfur crosslinking system crosslinking component. It has been found that it is possible to form a high-damping member that has performance and that has as little decrease in elastic modulus as possible after large deformation.
However, from the results of Examples 1 to 3 and Comparative Example 2, it was found that the blending ratio of EPM needs to be 50 parts by mass or less per 100 parts by mass of natural rubber in order to obtain such an effect.

  Further, from the results of Examples 1 to 3, it was found that in order to further improve the above effect, it is preferable that the blending ratio of EPM is 10 parts by mass or more, particularly 15 parts by mass or more per 100 parts by mass of natural rubber. It was.

H Hysteresis loop L ₁ straight line L ₂ perpendicular line W energy ΔW absorbed energy amount 1 disc 2 steel plate 3 specimen 4 center fixture 5 left fixture 6 fixture arm 7 joint 8 movable platen 9 joint

Claims (5)

  A diene rubber having sulfur crosslinkability, an ethylene propylene binary copolymer rubber having no sulfur crosslinkability of not more than 50 parts by mass per 100 parts by mass of the diene rubber, and a high content containing only a sulfur crosslinkable crosslinking component as a crosslinking component Attenuating composition.   The high attenuation composition according to claim 1, wherein a blending ratio of the ethylene-propylene binary copolymer rubber is 15 parts by mass or more per 100 parts by mass of the diene rubber.   The high-damping composition according to claim 1 or 2, wherein the diene rubber is at least one selected from the group consisting of natural rubber and isoprene rubber.   A seismic damper comprising a viscoelastic body made of the high damping composition according to any one of claims 1 to 3.   A base-isolated bearing comprising a viscoelastic body made of the high damping composition according to any one of claims 1 to 3.

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