JP2013043923A - High-damping composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-damping composition which can for example decrease elastic modulus thereof without reducing the size of a viscoelastic damper or the like, because the high-damping composition has high damping performance and also can form a high-damping member having rigidity lower than before.SOLUTION: Silica I and surface-treated calcium carbonate II are blended with diene rubber as a base polymer, so that: I+II is 100-160 pts.mass per 100 pts.mass of the diene rubber; and formula {I/(I+II)}×100 is 10-50 mass%.

Description

  The present invention relates to a highly damped composition that is a source of a highly damped member that relaxes or absorbs transmission of vibration energy.

For example, in a wide range of fields such as buildings and bridges, industrial machinery, aircraft, automobiles, railway vehicles, computers and peripheral equipment, household electrical equipment, and automobile tires, vibration energy transmission is alleviated. In order to absorb or absorb, that is, to perform seismic isolation, vibration control, vibration control, vibration isolation, etc., a high damping member containing rubber or the like as a base polymer is used.
The high damping member includes the base polymer in order to increase the hysteresis loss when vibration is applied to improve damping performance, i.e., to efficiently and quickly attenuate the energy of the vibration. In general, 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, a high attenuation member is formed by crosslinking.
As the base polymer, a diene rubber is preferably used. Since the diene rubber does not have a glass transition temperature near room temperature (2 to 35 ° C.), the temperature dependence of the damping performance near the room temperature, which is the most common use temperature range, is reduced and wide. There is an advantage that a high damping member showing stable damping performance in the temperature range can be formed.

The high-damping composition was prepared by adding silica and a silane compound (silylating agent) as a damping agent to the base polymer such as the diene rubber and kneading and reacting the silica and the silane compound. The thing etc. are known (refer patent document 1 grade | etc.,).
A damping damper for buildings, a so-called viscoelastic damper, for example, forms a viscoelastic body as a high damping member by causing a cross-linking reaction in a state where a sheet of high damping composition is sandwiched between steel plates and the like. The elastic body is constituted by integrating with the steel plate by vulcanization adhesion or the like.

The viscoelastic damper is required to have a damping function against minute deformations such as wind shaking in addition to a damping function against earthquake shaking.
In some buildings, there are cases where it is desired to disperse and use a plurality of viscoelastic dampers having a low elastic modulus, in which the elastic modulus of the viscoelastic damper is small.
However, the viscoelastic body formed by crosslinking the conventional high-damping composition contains a large amount of silica so as to exhibit good damping performance, and therefore has a tendency to increase in rigidity.

Therefore, in order to reduce the elastic modulus of such a viscoelastic damper with a highly rigid viscoelastic body so that it can exhibit a sufficient damping function against minute deformation, or to satisfy the requirements for distributed arrangement In addition, it is conceivable to reduce the overall size of the viscoelastic damper.
However, in that case, since the cross-sectional area of the viscoelastic body becomes small, for example, during large deformation due to an earthquake, the rotation in the out-of-plane direction increases, and in some cases, the viscoelastic body is easily broken. Become.

JP 7-41603 A

  An object of the present invention is to provide a high damping member that has high damping performance and lower rigidity than before, so that the elastic modulus can be reduced without downsizing, for example, a viscoelastic damper. It is to provide a damping composition.

  In the present invention, silica and surface-treated calcium carbonate are blended with diene rubber as a base polymer, and the total blending ratio of silica and surface-treated calcium carbonate per 100 parts by mass of the diene rubber is The proportion of the surface-treated calcium carbonate in the total amount of the silica and the surface-treated calcium carbonate is 10% by mass or more and 50% by mass or less. A damping composition.

Calcium carbonate functions as an attenuating agent like silica, and has a lower function of increasing the rigidity than silica. Therefore, by replacing a part of the silica with calcium carbonate, the rigidity of the high attenuation member has been improved so far. Can be kept to a lower level.
However, since the untreated calcium carbonate has a weak interaction with the diene rubber, if a part of the silica is replaced with calcium carbonate as described above, the damping performance of the high damping member is lower than when the entire amount is silica. Tend to.

  On the other hand, for example, the surface-treated calcium carbonate surface-treated with rosin acid or fatty acid has a good interaction with the diene rubber, so that the surface-treated calcium carbonate is used in combination with silica as described above. While suppressing the rigidity of the high damping member to a lower level than before, the damping performance of the high damping member can be improved to be equal to or higher than when the entire amount is silica.

Therefore, according to the high damping composition of the present invention, it is possible to form a high damping member having high damping performance and lower rigidity than before, so that, for example, the elastic modulus can be reduced without downsizing a viscoelastic damper or the like. Can be small.
Therefore, it is possible to prevent the occurrence of the problem that the viscoelastic body is destroyed due to the large rotation in the out-of-plane direction at the time of a large deformation due to an earthquake, for example.

  In the present invention, the total blending ratio of silica and surface-treated calcium carbonate per 100 parts by weight of the diene rubber is limited to 100 parts by weight or more and 160 parts by weight or less if the blending ratio is less than the above range. This is because the effect obtained by blending the two components as an attenuating agent cannot be obtained, and the attenuation performance of the high attenuation member is lowered. On the other hand, when the above range is exceeded, the effect of replacing part of the silica with the surface-treated calcium carbonate cannot be obtained, and the rigidity of the high attenuation member is increased.

  In the present invention, the proportion of the surface-treated calcium carbonate in the total amount of silica and the surface-treated calcium carbonate is limited to 10% by mass or more and 50% by mass or less. This is because the effect of replacing a part of the surface with calcium carbonate treated with the surface cannot be obtained, and the rigidity of the high damping member is increased. On the other hand, when the above range is exceeded, the ratio of silica is relatively reduced, and the damping performance of the high damping member is lowered.

The surface-treated calcium carbonate is at least selected from the group consisting of rosin acid and fatty acids in consideration of improving the interaction with the diene rubber described above and improving the damping performance of the high damping member. It is preferably calcium carbonate surface-treated with one kind.
In order to further reduce the rigidity of the high damping member, the high damping composition of the present invention may further contain liquid polyisoprene rubber as a softening agent. In particular, by blending a liquid polyisoprene rubber having a number average molecular weight of 40000 or less and a relatively small molecular weight, the rigidity of the high damping member can be further effectively reduced.

As the diene rubber, it is preferable to use natural rubber and butadiene rubber in combination in consideration of improving the damping performance of the high damping member.
When the viscoelastic body of a viscoelastic damper of a building as a high damping member is formed using the high damping composition of the present invention as a forming material, the viscoelastic body has a high damping performance. Therefore, the elastic modulus can be reduced without downsizing the entire viscoelastic damper including the viscoelastic body. For example, during large deformation due to an earthquake, rotation in an out-of-plane direction is possible. It is possible to prevent the occurrence of a problem that the viscoelastic body is destroyed due to the increase in size.

  According to the present invention, a high damping member having high damping performance and lower rigidity than before can be formed, and therefore, the elastic modulus can be reduced without downsizing, for example, a viscoelastic damper. A dampening composition can be provided.

It is a disassembled perspective view which decomposes | disassembles and shows the test body as a model of the said 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. 4A and 4B are diagrams for explaining the outline of a testing machine for displacing the test body 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 said testing machine.

  In the present invention, silica and surface-treated calcium carbonate are blended with diene rubber as a base polymer, and the total blending ratio of silica and surface-treated calcium carbonate per 100 parts by mass of the diene rubber is The proportion of the surface-treated calcium carbonate in the total amount of the silica and the surface-treated calcium carbonate is 10% by mass or more and 50% by mass or less. A damping composition.

(Diene rubber)
Examples of the diene rubber include one or more of natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, and the like.
The diene rubber is excellent in reactivity with the reactive component, and since the glass transition temperature does not exist near room temperature (2-35 ° C.), in the vicinity of the room temperature, which is the most common use temperature range, There is an advantage that it is possible to reduce the temperature dependence of characteristics such as rigidity and to form a high damping member that exhibits stable damping performance over a wide temperature range.

Considering the availability of materials and the like, it is preferable to use natural rubber as the diene rubber. In consideration of improving the damping performance of the high damping member, it is preferable to use natural rubber and butadiene rubber in combination as the diene rubber.
The blending ratio of both rubbers in the combined system is not particularly limited, but it is preferably 10% by mass or more and 30% by mass or less in terms of the ratio (mass%) of butadiene rubber in the total amount of both rubbers.

When the butadiene rubber is less than the above range, there is a possibility that the effect of improving the damping performance of the high damping member by using the butadiene rubber together with natural rubber may not be sufficiently obtained. On the other hand, when there is more butadiene rubber than the said range, since the ratio of a natural rubber will become relatively small, there exists a possibility that the production cost of a high attenuation | damping composition may rise.
(silica)
As the silica, any of wet process silica and dry process silica classified by the production method may be used. Silica has a BET specific surface area of 100 to 400 m ² / g, particularly 200 to 250 m ² / g in consideration of improving the effect of improving the damping performance of the high damping member by functioning as a filler. Is preferred. 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.
(Surface treatment calcium carbonate)
As the surface-treated calcium carbonate, for example, calcium carbonate obtained by surface-treating calcium carbonate such as synthetic calcium carbonate or heavy calcium carbonate with one or more of, for example, fatty acid, quaternary ammonium salt, rosin acid, and lignic acid. 1 type, or 2 or more types.

In particular, the surface-treated calcium carbonate surface-treated with at least one selected from the group consisting of rosin acid and fatty acid improves the interaction with the diene rubber and has an excellent function of improving the damping performance of the high damping member. Therefore, it is preferable.
Examples of the surface-treated calcium carbonate include Shiroishi Hana (registered trademark) DD manufactured by Shiraishi Calcium Co., Ltd. (synthesized calcium carbonate surface-treated with rosin acid), Shiroka Hana CC [synthesized calcium carbonate surface-treated with fatty acid] Etc.

(Combination ratio of silica and surface-treated calcium carbonate)
As described above, the total blending ratio of silica and surface-treated calcium carbonate per 100 parts by mass of the diene rubber is 100 parts by mass or more and 160 parts by mass or less, and the silica and surface treatment of the surface-treated calcium carbonate. The proportion of calcium carbonate in the total amount needs to be 10% by mass or more and 50% by mass or less.

  The total compounding ratio of the silica and the surface-treated calcium carbonate is limited to the above range. When the total compounding ratio is less than 100 parts by mass, the effect of blending the two components as an attenuating agent is obtained. This is because the damping performance of the high damping member is not obtained. On the other hand, when the amount exceeds 160 parts by mass, the effect of replacing part of the silica with the surface-treated calcium carbonate cannot be obtained, and the rigidity of the high attenuation member is increased.

In consideration of further improving the damping performance while further suppressing the rigidity of the high damping member, the total blending ratio of the silica and the surface-treated calcium carbonate is 120 parts by mass or more, particularly within the above range. The amount is preferably 130 parts by mass or more, more preferably 150 parts by mass or less, and particularly preferably 140 parts by mass or less.
In addition, the proportion of the surface-treated calcium carbonate in the total amount of silica and the surface-treated calcium carbonate is limited to the above range. If the proportion is less than 10% by mass, a part of the silica is treated with the surface-treated calcium carbonate. This is because the effect of the replacement cannot be obtained, and the rigidity of the high damping member is increased. On the other hand, when it exceeds 50 mass%, the ratio of silica is relatively reduced, and the attenuation performance of the high attenuation member is lowered.

In consideration of further improving the damping performance while further suppressing the rigidity of the high damping member, the ratio of the surface-treated calcium carbonate is 20% by mass or more, particularly 30% by mass or more even within the above range. Is preferably 40% by mass or less, particularly preferably 35% by mass or less.
(Softener)
The high damping composition of the present invention may further contain a softening agent in order to further reduce the rigidity of the high damping member. Examples of the softening agent include liquid rubber. Examples of the liquid rubber include various rubbers that are liquid at room temperature (3-35 ° 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), LIR-50 (number average molecular weight: 54000) manufactured by Kuraray Co., Ltd., and the like. In particular, the rigidity of the high damping member can be further effectively reduced by blending a liquid polyisoprene rubber having a relatively low molecular weight such as LIR-30 and having a number average molecular weight of 40000 or less.

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.
If the blending ratio is less than the above range, the effect of lowering the rigidity of the high damping member by blending the liquid polyisoprene rubber may not be sufficiently obtained. On the other hand, if the above range is exceeded, the damping performance of the high damping member may be reduced.

(Other ingredients)
The high attenuation composition of the present invention may further contain a filler other than silica and surface-treated calcium carbonate, or a crosslinking component for crosslinking the diene rubber at an appropriate ratio.
Examples of the other fillers include carbon black.

As the carbon black, one or more of carbon blacks that can function as a filler among various carbon blacks classified according to the production method thereof can be used.
The blending ratio of carbon black is not particularly limited, but is preferably 1 part by mass or more and 5 parts by mass or less per 100 parts by mass of the diene rubber.

  As the crosslinking component, various crosslinking components capable of crosslinking the diene rubber can be used. In particular, it is preferable to use a sulfur vulcanized crosslinking component. Examples of the sulfur-vulcanized crosslinking component include a combination of a vulcanizing agent, a vulcanization accelerator, and a vulcanization acceleration aid. In particular, it is preferable to combine a vulcanizing agent, a vulcanization accelerator, and a vulcanization acceleration aid that hardly cause the problem that the rubber elasticity of the high damping member increases and the damping performance decreases.

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

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

The blending ratio of the vulcanizing agent, the vulcanization accelerator, and the vulcanization accelerating agent may be appropriately adjusted according to the characteristics such as the damping performance and the rigidity that differ depending on the use of the high damping member.
The high attenuation composition of the present invention may further contain various additives such as a silane compound and a softening agent other than the liquid polyisoprene rubber, a tackifier, and an anti-aging agent at an appropriate ratio, if necessary. May be.

  Among these, 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.
Examples of the silane compound include KBE-103 (phenyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.
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.

Examples of other softeners include liquid rubber other than the liquid polyisoprene rubber exemplified above, or coumarone indene resin.
Examples of the coumarone indene resin include various coumarone indene resins which are mainly composed of a polymer of coumarone and indene and 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 Nikko Chemical Co., Ltd. [average molecular weight: 770, softening point: 90 ° C., acid value: 1.0 KOH mg / g or less, hydroxyl group] Value: 25 KOH mg / g, bromine value 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 value 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 is preferably 5 parts by mass or more and more preferably 20 parts by mass or less per 100 parts by mass of the diene rubber.
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.

Although the blending ratio of the petroleum resin is not particularly limited, 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.
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.

  The high damping member that can be manufactured using the high damping composition of the present invention includes, for example, a seismic isolation damper that is incorporated in the foundation of a building such as a building, and a damping damper that is incorporated in the structure of the building. Damping members for cables such as suspension bridges and cable-stayed bridges, anti-vibration members for industrial machines, aircraft, automobiles, railway vehicles, etc., anti-vibration members for computers and their peripheral devices, household electric appliances, etc. Examples include treads for automobile tires.

According to the present invention, the above-described diene rubber, silica, surface-treated calcium carbonate, and other various components, and combinations and blending ratios thereof can be adjusted to achieve high attenuation having excellent attenuation performance suitable for each application. A member can be obtained.
In particular, when a viscoelastic body of a building as a high damping member is formed using the high damping composition of the present invention as a forming material, the viscoelastic body has high damping performance and Therefore, the elastic modulus can be reduced without downsizing the entire viscoelastic damper including the viscoelastic body. For example, during large deformation due to an earthquake, rotation in an out-of-plane direction is possible. It is possible to prevent the occurrence of a problem that the viscoelastic body is destroyed due to the increase in size.

<Example 1>
(Preparation of highly attenuated composition)
100 parts by mass of natural rubber (SMR (Standard Malaysian Rubber) -CV60) as a base polymer, 90 parts by mass of silica (NipSil (nip seal) KQ made by Tosoh Silica Co., Ltd.), surface treated calcium carbonate [Shiraishi Calcium Co., Ltd. Hakuenka (registered trademark) DD, synthetic calcium carbonate surface-treated with rosin acid] 45 parts by mass, and liquid polyisoprene rubber [LIR-30 manufactured by Kuraray Co., Ltd., number average molecular weight: 28000] 35 parts by mass The components shown in Table 1 below were blended and kneaded using a closed kneader to prepare a highly attenuated composition.

  The total blending ratio of silica and surface-treated calcium carbonate was 135 parts by mass per 100 parts by mass of natural rubber. The proportion of the surface-treated calcium carbonate in the total amount of silica and surface-treated calcium carbonate was 33.3% by mass.

Each component in the table is as follows.
Silane compound: Phenyltriethoxysilane, KBE-103 manufactured by Shin-Etsu Chemical Co., Ltd.
Carbon Black: FEF, Sea Toe SO manufactured by Tokai Carbon Co., Ltd.
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
Dicyclopentadiene-based petroleum resin: softening point 105 ° C., Marukaretsu (registered trademark) M890A manufactured by Maruzen Petrochemical Co., Ltd.
Coumarone resin: softening point 90 ° C., Nikko Chemical Co., Ltd. Escron (registered trademark) G-90
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.
<Example 2>
Highly attenuated composition in the same manner as in Example 1 except that 45 parts by mass of surface-treated calcium carbonate obtained by subjecting synthetic calcium carbonate to a surface treatment with a fatty acid [Shiraishi Hana (registered trademark) CC manufactured by Shiraishi Calcium Co., Ltd.] A product was prepared.

The total blending ratio of silica and surface-treated calcium carbonate was 135 parts by mass per 100 parts by mass of natural rubber. The proportion of the surface-treated calcium carbonate in the total amount of silica and surface-treated calcium carbonate was 33.3% by mass.
<Example 3>
A blend of natural rubber [SMR (Standard Malaysian Rubber) -CV60] and butadiene rubber [UBEPOL (registered trademark) BR130B manufactured by Ube Industries, Ltd.] at a mass ratio of 80/20 as a base polymer 100 mass A highly attenuating composition was prepared in the same manner as in Example 1 except that the parts were used.

The total blending ratio of silica and surface-treated calcium carbonate was 135 parts by mass per 100 parts by mass of natural rubber + butadiene rubber. The proportion of the surface-treated calcium carbonate in the total amount of silica and surface-treated calcium carbonate was 33.3% by mass.
<Comparative example 1>
A highly attenuating composition was prepared in the same manner as in Example 1 except that the surface-treated calcium carbonate was not blended and the blending ratio of silica was 135 parts by mass.

The total blending ratio of silica and surface-treated calcium carbonate was 135 parts by mass per 100 parts by mass of natural rubber. The proportion of the surface-treated calcium carbonate in the total amount of silica and surface-treated calcium carbonate was 0% by mass.
<Comparative example 2>
A highly attenuated composition was prepared in the same manner as in Comparative Example 1 except that the blending ratio of silica was 90 parts by mass.

The total blending ratio of silica and surface-treated calcium carbonate was 90 parts by mass per 100 parts by mass of natural rubber. The proportion of the surface-treated calcium carbonate in the total amount of silica and surface-treated calcium carbonate was 0% by mass.
<Comparative Example 3>
A highly attenuating composition was prepared in the same manner as in Comparative Example 1 except that 35 parts by mass of a liquid polyisoprene rubber having a number average molecular weight of 54,000 [LIR-50 manufactured by Kuraray Co., Ltd.] was blended.

The total blending ratio of silica and surface-treated calcium carbonate was 135 parts by mass per 100 parts by mass of natural rubber. The proportion of the surface-treated calcium carbonate in the total amount of silica and surface-treated calcium carbonate was 0% by mass.
<Comparative example 4>
Highly attenuated composition in the same manner as in Example 1 except that 45 parts by weight of untreated heavy calcium carbonate (Shiraishi Calcium Co., Ltd., Whiten (registered trademark) BF-300) not surface-treated is blended. A product was prepared.

The total blending ratio of silica and heavy calcium carbonate was 135 parts by mass per 100 parts by mass of natural rubber. The proportion of heavy calcium carbonate in the total amount of silica and heavy calcium carbonate was 33.3% by mass.
<Comparative Example 5>
Except that the blending ratio of the surface-treated calcium carbonate [Shiraishi Hana (registered trademark) DD manufactured by Shiraishi Calcium Co., Ltd.] was 10 parts by mass and the blending ratio of silica was 125 parts by mass, the same as in Example 1. A damping composition was prepared.

The total blending ratio of silica and surface-treated calcium carbonate was 135 parts by mass per 100 parts by mass of natural rubber. The proportion of the surface-treated calcium carbonate in the total amount of silica and surface-treated calcium carbonate was 7.4% by mass.
<Comparative Example 6>
Except that the blending ratio of the surface-treated calcium carbonate [Shiraishi Hana (registered trademark) DD manufactured by Shiraishi Calcium Co., Ltd.] is 75 parts by mass and the blending ratio of silica is 60 parts by mass, the same as in Example 1. A damping composition was prepared.

The total blending ratio of silica and surface-treated calcium carbonate was 135 parts by mass per 100 parts by mass of natural rubber. The proportion of the surface-treated calcium carbonate in the total amount of silica and surface-treated calcium carbonate was 55.6% by mass.
<Comparative Example 7>
Except that the blending ratio of the surface-treated calcium carbonate [Shiraishi Hana (registered trademark) DD manufactured by Shiraishi Calcium Co., Ltd.] was 30 parts by mass and the blending ratio of silica was 60 parts by mass, the amount was as high as in Example 1. A damping composition was prepared.

The total blending ratio of silica and surface-treated calcium carbonate was 90 parts by mass per 100 parts by mass of natural rubber. The proportion of the surface-treated calcium carbonate in the total amount of silica and surface-treated calcium carbonate was 33.3% by mass.
<Comparative Example 8>
The amount of the surface-treated calcium carbonate [Shiraishi Hana (registered trademark) DD manufactured by Shiraishi Calcium Co., Ltd.] was 60 parts by mass, and the silica compounding ratio was 120 parts by mass. A damping composition was prepared.

The total blending ratio of silica and surface-treated calcium carbonate was 180 parts by mass per 100 parts by mass of natural rubber. The proportion of the surface-treated calcium carbonate in the total amount of silica and surface-treated calcium carbonate was 33.3% by mass.
<Attenuation characteristic test>
(Preparation of test specimen)
The high attenuation compositions prepared in Examples, Comparative Examples, and Conventional Examples are extruded into a sheet shape and then punched to produce a disk 1 (thickness 5 mm × diameter 25 mm) as shown in FIG. The disk 1 is formed by superimposing a rectangular plate-shaped steel plate 2 of thickness 6 mm × length 44 mm × width 44 mm on both the front and back surfaces of the steel sheet and heating to 150 ° C. while pressing in the laminating direction. While the damping composition was vulcanized, the disk 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. One left and right fixing jig 5 was 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 connected to the lower movable platen 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 the white arrow in the figure, and the disk 1 of the test body 3 is moved to the position shown in FIG. As shown in the figure, the test body 3 is strained and deformed in a direction orthogonal to the stacking direction, and from this state, the movable platen 8 is moved in a direction opposite to the direction of the fixed arm 6 as indicated by a white arrow in the figure. The operation of the test body 3 when the disk 1 of the test body 3 is repeatedly distorted or deformed, that is, vibrated, with the operation of displacing it down and returning to the state shown in FIG. A hysteresis loop H (see FIG. 3) indicating the relationship between the displacement (mm) of the disk 1 in the direction perpendicular to the stacking direction and the load (N) was obtained.

The measurement is performed for 3 cycles under the environment of a temperature of 20 ° C. to obtain the third value. The maximum amount of displacement was set so that the amount of deviation of the two steel plates 2 sandwiching the disc 1 in the direction perpendicular to the stacking direction 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 measurement, determine the slope Keq (N / mm) of the straight line L ₁ shown by a thick solid line in the figure, the 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 (2):

The equivalent shear modulus Geq (N / mm ² ) was determined by It can be determined that the lower the equivalent shear modulus is, the lower the rigidity of the specimen 3 is and the better the modulus of elasticity. Here, those having an equivalent shear modulus of 0.25 N / mm ² or less were evaluated as good elastic modulus, and those having an equivalent shear modulus exceeding 0.25 N / mm ² were evaluated as defective elastic modulus.
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 the figure, and the horizontal axis, and a straight line L ₁ and the hysteresis loop H elastic strain energy W represented by the surface area of the region surrounded by the perpendicular L ₂ grated on the horizontal axis from the intersection of the formula (3):

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. Here, those having a Heq of 0.25 or more were evaluated as good attenuation performance, and those having a Heq of less than 0.25 were evaluated as poor attenuation performance.
The above results are shown in Tables 2 and 3.

From the results of Comparative Examples 1 and 2 in Table 2, it was found that the rigidity tends to increase when silica is blended alone. Further, from the result of Comparative Example 3, it was found that when the liquid polyisoprene rubber having a number average molecular weight exceeding 40,000 is used, the rigidity is further increased.
Moreover, from the result of Comparative Example 4 in Table 3, it was found that when silica and untreated calcium carbonate were used in combination, the rigidity could be kept low but the damping performance was lowered.

On the other hand, from the results of Examples 1 to 3 in Table 2, when silica and surface-treated calcium carbonate are used in combination, a high damping member having high damping performance and lower rigidity than before can be formed. understood.
However, from the results of Examples 1 to 3 and Comparative Examples 5 to 8 in Table 3, if the total blending ratio of silica and surface-treated calcium carbonate (I + II in Tables 2 and 3) is less than 100 parts by mass, the damping performance is When it exceeds 160 parts by mass, the rigidity becomes high. Therefore, it has been found that the total blending ratio needs to be 100 parts by mass or more and 160 parts by mass or less.

  Also, the ratio of the surface-treated calcium carbonate to the total amount of silica and surface-treated calcium carbonate, that is, in Tables 2 and 3:

However, it was also found that the ratio needs to be 10% by mass or more and 50% by mass or less because the rigidity increases when the content is less than 10% by mass and the damping performance decreases when the content exceeds 50% by mass.

DESCRIPTION OF SYMBOLS 1 Disc 2 Steel plate 3 Specimen 4 Center fixing jig 5 Left and right fixing jig 6 Fixed arm 7 Joint 8 Movable platen 9 Joint H Hysteresis loop L ₁ Straight line Keq Inclination L ₂ Vertical line W Energy ΔW Absorbed energy amount

Claims (5)

  Silica and surface-treated calcium carbonate are blended with diene rubber as a base polymer, and the total blending ratio of silica and surface-treated calcium carbonate per 100 parts by weight of diene rubber is 100 parts by mass or more. 160% by mass or less, and the proportion of the surface-treated calcium carbonate in the total amount of silica and surface-treated calcium carbonate is 10% by mass or more and 50% by mass or less.   The highly attenuated composition according to claim 1, wherein the surface-treated calcium carbonate is calcium carbonate surface-treated with at least one selected from the group consisting of rosin acid and fatty acid.   The high-damping composition according to claim 1 or 2, further comprising a liquid polyisoprene rubber having a number average molecular weight of 40000 or less as a softening agent.   The high-damping composition according to any one of claims 1 to 3, wherein natural rubber and butadiene rubber are used in combination as the diene rubber.   The high attenuation composition according to any one of claims 1 to 4, which is used as a material for forming a viscoelastic damper of a building.

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