Damping rubber composition and viscoelastic damper

Abstract

To provide a damping rubber composition which enables formation of a damping member that has excellent workability, has excellent damping property in a low strain region such as wind swaying, and has small damping property in a low strain region and temperature dependence of shear elastic modulus.SOLUTION: A damping rubber composition contains base material rubber, a tackifier, carbon black, silica, a vulcanizer and a vulcanization accelerator. The base material rubber contains polyisoprene-based rubber and polybutadiene-based rubber, a percentage content of the polybutadiene-based rubber in the base material rubber is 20 or more and 60 mass% or less, the tackifier is at least one selected from the group consisting of a petroleum-based resin, a terpene-based resin, a coumarone-based resin and a styrenic resin, the content of the tackifier is 60 or more and 100 pts.mass or less with respect to 100 pts.mass of the base material rubber, the content of the carbon black is 100 or more and 160 pts.mass or less with respect to 100 pts.mass of the base material rubber, and the content of the silica is 5 or more and 60 pts.mass or less with respect to 100 pts.mass of the base material rubber.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a damping rubber composition and a viscoelastic damper including a damping member using the same.

Background Art

[0002] Conventionally, in buildings such as houses and buildings, and bridges, means for absorbing vibration energy generated by earthquakes, traffic vibrations, wind sway, etc. have been installed. Among them, a tuned mass damper (TMD) is known as a means for suppressing sway in a low strain region such as wind sway. However, the TMD is large-sized and the costs for introduction and maintenance are high. On the other hand, a viscoelastic damper including a damping member (viscoelastic body) is relatively inexpensive and has excellent vibration damping performance against strong vibrations such as large earthquakes, and can also exhibit a vibration suppression effect against minute vibrations such as wind sway. Therefore, it is widely used as a means for imparting seismic isolation, earthquake control, vibration control, vibration prevention, etc.

[0003] For example, Patent Document 1 discloses a high damping rubber composition containing carbon black, silica, and rosin-modified phenol and / or rosin ester with respect to rubber containing natural rubber and / or isoprene rubber.

[0004] Patent Document 2 discloses a high damping rubber composition containing at least a rubber component and a rosin acid metal salt.

[0005] Patent Document 3 discloses a silica-filled high damping rubber composition in which 30 to 200 parts by weight of silica is added to 100 parts by weight of a base rubber having a C-C bond in the main chain, and 5 to 50% by weight of a specific silane compound is blended with the silica and kneaded.

[0006] Patent Document 4 discloses a high damping rubber composition containing (A) butyl rubber, (B) at least one of a styrene-isobutylene block copolymer (SIB) and a styrene-isobutylene-styrene block copolymer (SIBS), (C) a non-polar alicyclic saturated hydrocarbon resin, and (D) sulfur.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0008] For a damping member for suppressing vibrations in a low strain range (e.g., about 2%) such as wind sway, excellent damping performance is required in the low strain range. In addition, considering environmental conditions, it is also required that the damping performance and the temperature dependence of the shear modulus in the low strain range near room temperature (e.g., 10°C to 30°C) be small.

[0009] In addition, good workability is always required because it improves productivity, reduces the energy consumption required for production, and leads to a reduction in production costs.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a damping rubber composition that forms a damping member having good workability, excellent damping performance in a low strain range such as wind sway, and small temperature dependence of the damping performance and the shear modulus in the low strain range. A further object of the present invention is to provide a viscoelastic damper including a damping member obtained by curing the damping rubber composition.

Means for Solving the Problems

[0011] The damping rubber composition of the present invention that has solved the above problems is a damping rubber composition containing a base rubber, tackifier, carbon black, silica, vulcanizing agent, and vulcanization accelerator, wherein the base rubber contains a polyisoprene rubber and a polybutadiene rubber, the content of the polybutadiene rubber in the base rubber is 20% by mass or more and 60% by mass or less, the tackifier is at least one selected from the group consisting of petroleum resins, terpene resins, coumarone resins, and styrene resins, the content of the tackifier is 60 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the base rubber, the content of the carbon black is 100 parts by mass or more and 160 parts by mass or less with respect to 100 parts by mass of the base rubber, and the content of the silica is 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the base rubber.

Advantages of the Invention

[0012] According to the present invention, a damping rubber composition is obtained that has good processability, excellent damping properties in a low strain range such as wind sway, and small temperature dependencies of the damping properties and shear elastic modulus in the low strain range, and forms a damping member. According to the present invention, a viscoelastic damper is obtained that has excellent damping properties in a low strain range such as wind sway, and small temperature dependencies of the damping properties and shear elastic modulus in the low strain range.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0014] <Damping rubber composition> The damping rubber composition of the present invention is a damping rubber composition containing a base rubber, a tackifier, carbon black, silica, a vulcanizing agent and a vulcanization accelerator, wherein the base rubber contains a polyisoprene rubber and a polybutadiene rubber, and the content of the polybutadiene rubber in the base rubber is 20% by mass or more and 60% by mass or less, the tackifier is at least one selected from the group consisting of a petroleum resin, a terpene resin, a coumarone resin and a styrene resin, the content of the tackifier is 60 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the base rubber, the content of the carbon black is 100 parts by mass or more and 160 parts by mass or less with respect to 100 parts by mass of the base rubber, and the content of the silica is 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the base rubber.

[0015] According to the present invention, due to the interaction of polyisoprene rubber, polybutadiene rubber, tackifier, carbon black, and silica, the resulting damping member generates hysteresis loss in the low strain region. A damping member that generates hysteresis loss in the low strain region has improved damping performance in the low strain region. Since polybutadiene rubber is more flexible than polyisoprene rubber, by blending polybutadiene rubber, it is possible to reduce the variation in physical properties (such as rigidity) of the damping member due to temperature (especially at low temperatures). Also, by blending a specific type of tackifier, the damping property of the damping member can be increased. By blending a specific amount of polybutadiene rubber and a specific amount and specific type of tackifier, it is possible to reduce the temperature dependence of the damping property and shear modulus in the low strain region while maintaining the damping property in the low strain region. Furthermore, carbon black and silica, which are inorganic fillers, have no temperature dependence and can contribute to the improvement of damping property and moldability. In particular, silica has a higher interaction between fillers compared to carbon black, and thus has a higher effect of improving the damping property. By using carbon black and silica in combination, it is possible to improve the damping property of the damping member in the low strain region and the temperature dependence of the damping property and shear modulus in the low strain region while maintaining good processability of the rubber composition.

[0016] Hereinafter, each component that may be included in the damping rubber composition of the present invention will be described. (Base rubber) The base rubber contained in the damping rubber composition of the present invention contains polyisoprene rubber and polybutadiene rubber.

[0017] The polyisoprene rubber is not particularly limited as long as it is a rubber having a structural unit derived from isoprene (preferably, a rubber mainly having a structural unit derived from isoprene). Examples of the polyisoprene rubber include natural rubber (NR) and synthetic rubber. Natural rubber is derived from rubber-containing plants and contains pure cis-1,4-polyisoprene. Synthetic polyisoprene rubber is synthesized by polymerizing a monomer containing isoprene (preferably, a monomer having isoprene as a main component). Note that the natural rubber and synthetic polyisoprene rubber may be modified rubbers. These polyisoprene rubbers may be used alone or in combination of two types.

[0018] Examples of the natural rubber include various grades of natural rubber such as SMR (Standard Malaysian Rubber)-CV60 and various deproteinized natural rubbers.

[0019] Examples of the synthetic polyisoprene rubber include polyisoprene rubber (IR) and copolymer rubbers of isoprene and other monomer components.

[0020] Examples of other monomer components that can constitute the synthetic polyisoprene rubber include butadiene, styrene, ethylene, propylene, acrylonitrile, chloroprene, and the like. These other monomer components may be used alone or in combination of two types.

[0021] The synthetic polyisoprene rubber preferably contains 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more of the structural unit derived from isoprene. Note that the upper limit of the structural unit derived from isoprene is 100% by mass.

[0022] Among the synthetic polyisoprene rubbers, polyisoprene rubber (IR) is preferred, and a high-cis-1,4-polyisoprene rubber containing 90% by mass or more (preferably 95% by mass or more) of cis-1,4 bonds is more preferred. By using the high-cis-1,4-polyisoprene rubber, the damping property in the low strain region becomes better.

[0023] Specific examples of the synthetic polyisoprene rubber include, for example, commercially available products such as Nipol (registered trademark) IR series (for example, IR2200) manufactured by Zeon Corporation of Japan.

[0024] The Mooney viscosity (ML 1+4 (100 °C) is preferably 40 or more, more preferably 45 or more, still more preferably 50 or more, preferably 120 or less, more preferably 110 or less, and still more preferably 100 or less. If the Mooney viscosity of the polyisoprene rubber is within the above range, the effects of the present invention can be obtained more favorably. The Mooney viscosity (ML 1+4 (100 °C)) referred to in the present invention is a value measured under the conditions of using an L rotor, a preheating time of 1 minute, a rotor rotation time of 4 minutes, and 100 °C in accordance with JIS K6300.

[0025] The content of the polyisoprene rubber in the base rubber is preferably 40% by mass or more, more preferably 45% by mass or more, still more preferably 50% by mass or more, preferably 80% by mass or less, more preferably 75% by mass or less, and still more preferably 70% by mass or less. If the content of the polyisoprene rubber is 40% by mass or more, the damping property in the low strain region becomes better, and if it is 80% by mass or less, the damping property in the low strain region and the temperature dependence of the shear elastic modulus are more improved.

[0026] The polybutadiene rubber is not particularly limited as long as it is a rubber having a structural unit derived from butadiene (preferably, a rubber mainly having a structural unit derived from butadiene). Examples of the polybutadiene rubber include those synthesized by polymerizing a monomer containing butadiene (preferably, a monomer having butadiene as a main component). Note that the polybutadiene rubber may be a modified rubber. The polybutadiene rubber may be used alone or in combination of two types.

[0027] Examples of the polybutadiene rubber include polybutadiene rubber (BR) and copolymer rubbers of butadiene and other monomer components.

[0028] Examples of other monomer components that can constitute the polybutadiene rubber include isoprene, styrene, ethylene, propylene, acrylonitrile, chloroprene, and the like. These other monomer components may be used alone or in combination of two types.

[0029] The polybutadiene rubber preferably contains 50% by mass or more of the structural unit derived from butadiene, more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more. The upper limit of the structural unit derived from butadiene is 100% by mass.

[0030] Among the polybutadiene rubbers, polybutadiene rubber (BR) is preferred, and a high-cis-1,4-polybutadiene rubber containing 90% by mass or more (preferably 95% by mass or more) of cis-1,4 bonds is more preferred. The high-cis-1,4-polybutadiene rubber has less variation in physical properties due to temperature (especially at low temperatures). By using the high-cis-1,4-polybutadiene rubber, the damping property in the low-strain region of the damping member and the temperature dependence of the shear modulus can be further reduced.

[0031] Specific examples of the polybutadiene rubber include, for example, commercially available products such as the UBEPOL (registered trademark) BR series (e.g., BR130B, BR360B, BR150B, BR150L, BR360L) manufactured by Ube Industries, Ltd., and the Nipol (registered trademark) SBR series (e.g., SBR1502, SBR1723) manufactured by Zeon Corporation, Japan.

[0032] The Mooney viscosity (ML 1+4 (100 °C) of the polybutadiene rubber is preferably 15 or more, more preferably 20 or more, still more preferably 25 or more, preferably 80 or less, more preferably 70 or less, and still more preferably 60 or less. If the Mooney viscosity of the polybutadiene rubber is within the above range, the effects of the present invention can be obtained more favorably.

[0033] The content of the polybutadiene rubber in the base rubber is preferably 20% by mass or more, more preferably 25% by mass or more, still more preferably 30% by mass or more, preferably 60% by mass or less, more preferably 55% by mass or less, and still more preferably 50% by mass or less. If the content of the polybutadiene rubber is 20% by mass or more, the damping property in the low strain region and the temperature dependence of the shear modulus are improved, and if it is 60% by mass or less, the damping property in the low strain region is improved.

[0034] In addition to the above-mentioned polyisoprene rubber and polybutadiene rubber, the base rubber may contain other rubber components. Examples of the other rubber components include, for example, butyl rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, etc., and modified rubbers thereof. These other rubber components may be used alone or in combination of two or more.

[0035] The total content of polyisoprene rubber and polybutadiene rubber in the base rubber is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more. The upper limit of the total content is 100% by mass. If the total content of polyisoprene rubber and polybutadiene rubber is within the above range, the effects of the present invention can be obtained more favorably.

[0036] The mass ratio of polyisoprene rubber to polybutadiene rubber (polyisoprene rubber / polybutadiene rubber) is preferably 0.5 or more, more preferably 1.0 or more, still more preferably 1.2 or more, preferably 4.0 or less, more preferably 3.0 or less, and still more preferably 2.0 or less. If the mass ratio (polyisoprene rubber / polybutadiene rubber) is within the above range, the damping property in the low strain region, and the damping property in the low strain region and the temperature dependence of the shear modulus are further improved.

[0037] In addition, each rubber component (polyisoprene rubber, polybutadiene rubber, other rubber components) contained in the damping rubber composition of the present invention may be either an oil-extended type containing extender oil or a non-oil-extended type not containing extender oil. When using an oil-extended type, the rubber content and mass ratio are values calculated based on the rubber content excluding the extender oil.

[0038] Each rubber component contained in the damping rubber composition of the present invention preferably exhibits a solid state at 25°C. That is, it is preferable that the base rubber of the present invention does not contain a liquid rubber that is liquid at 25°C and is usually used as a softening agent.

[0039] (Adhesion promoter) The adhesion promoter contained in the damping rubber composition of the present invention is at least one selected from the group consisting of petroleum resins, terpene resins, coumarone resins, and styrene resins. These adhesion promoters may be used alone or in combination of two or more.

[0040] As the petroleum resin, it is a resin polymerized using an aliphatic (cyclic) diolefin-based unsaturated hydrocarbon fraction (C5 fraction) or an aromatic olefin-based unsaturated hydrocarbon fraction (C9 fraction) obtained by thermal decomposition of petroleum naphtha as a raw material. For example, an aliphatic (cyclic) petroleum resin obtained by (co)polymerizing the C5 fraction (or a high-purity component extracted from the C5 fraction), an aromatic petroleum resin obtained by (co)polymerizing the C9 fraction (or a high-purity component extracted from the C9 fraction), an aliphatic (cyclic)-aromatic petroleum resin obtained by copolymerizing the C5 fraction and the C9 fraction (or high-purity components extracted from these fractions), hydrogenated products thereof, etc. are included. These petroleum resins may be used alone or in combination of two or more.

[0041] Specific examples of the petroleum resin include, for example, Quintone (registered trademark) 1000 series (e.g., Quintone 1920, Quintone 2940) and 100 series (e.g., Quintone E200SN) manufactured by Nippon Zeon Co., Ltd., Petcocol (registered trademark) series (e.g., Petcocol 120, Petcocol 130, Petcocol LX) and Petro Tack (registered trademark) series (e.g., Petro Tack 60, Petro Tack 70) manufactured by Tosoh Corporation, Structol (registered trademark) series (e.g., Structol 40MS, Structol 60NS) manufactured by Structol Co., Ltd., Marcares (registered trademark) M series (e.g., Marcares M-890A) manufactured by Maruzen Petrochemical Co., Ltd., and other commercially available products.

[0042] As the terpene resin, it is a resin having a structural unit mainly derived from a terpene compound. For example, a polyterpene resin obtained by (co)polymerizing a terpene compound, a terpene-aromatic resin obtained by copolymerizing a terpene compound and an aromatic compound, an aromatic-modified polyterpene resin obtained by modifying a polyterpene resin with an aromatic compound, hydrogenated products thereof, etc. are included. These terpene resins may be used alone or in combination of two or more.

[0043] The terpene compound is a hydrocarbon represented by the composition of (C5H8)n and its oxygen-containing derivatives, and is a compound having a terpene classified into monoterpene (C 10 H 16 ), sesquiterpene (C 15 H 24 ), diterpene (C 20 H 32 ) etc. as a basic skeleton. Examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, allo-ocimene, ocimene, α-farnesene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol and the like. These terpene compounds may be used alone or in combination of two or more.

[0044] Examples of the aromatic compound include phenol compounds such as phenol, alkylphenol, alkoxyphenol, and unsaturated hydrocarbon group-containing phenol; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and unsaturated hydrocarbon group-containing naphthol; and styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene. These aromatic compounds may be used alone or in combination of two or more.

[0045] Specific examples of the terpene resin include commercially available products such as the Sylvatraxx (registered trademark) series (for example, Sylvatraxx4150, Sylvatraxx4125) and Sylvares (registered trademark) series (for example, SylvaresTR B115, SylvaresTR M1115) manufactured by Clayton.

[0046] The coumarone resin is a resin having a structural unit mainly derived from coumarone, and examples thereof include coumarone resin, coumarone-indene resin, and copolymer resin mainly composed of coumarone, indene and styrene. These coumarone resins may be used alone or in combination of two or more.

[0047] Specific examples of the coumarone resin include, for example, commercially available products such as Nitto Resin (registered trademark) Coumarone series manufactured by Nitto Chemical Co., Ltd. (e.g., Nitto Resin Coumarone G-90, Nitto Resin Coumarone L-5, Nitto Resin Coumarone L-20).

[0048] The styrene resin is a polymer containing a styrene monomer as a constituent monomer. For example, in addition to a homopolymer obtained by polymerizing one type of styrene monomer alone and a copolymer obtained by copolymerizing two or more types of styrene monomers, a copolymer of a styrene monomer and another monomer copolymerizable therewith is also included.

[0049] Examples of the styrene monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc. These may be used alone or in combination of two or more. Among them, styrene and α-methylstyrene are more preferred.

[0050] In order to obtain better effects, the styrene resin is preferably an α-methylstyrene resin (α-methylstyrene homopolymer, copolymer of styrene and α-methylstyrene, etc.), and more preferably a styrene-α-methylstyrene resin (copolymer of styrene and α-methylstyrene).

[0051] Examples of the tackifier include a tackifier (a) having a glass transition temperature (Tg) of 40°C to 50°C, a tackifier (b) having a glass transition temperature (Tg) of 60°C to 70°C, and a tackifier (c) having a glass transition temperature (Tg) different from those of the tackifiers (a) and (b) described below. In the present invention, it is preferable that the tackifier contains the tackifier (a), more preferably contains the tackifier (a) and the tackifier (b), and even more preferably contains the tackifier (a), the tackifier (b), and the tackifier (c). The glass transition temperature (Tg) can be measured, for example, by DSC (differential scanning calorimetry).

[0052] The glass transition temperature (Tg) of the tackifier (a) is preferably 40°C or higher, more preferably 41°C or higher, even more preferably 42°C or higher, preferably 50°C or lower, more preferably 48°C or lower, and even more preferably 45°C or lower. When the glass transition temperature (Tg) of the tackifier (a) is within the above range, the effects of the present invention can be obtained more favorably.

[0053] Specific examples of the tackifier (a) include commercially available products such as Nitto Resin Cumarone G-90 manufactured by Nitto Kasei Co., Ltd.

[0054] The content of the tackifier (a) is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, even more preferably 30 parts by mass or more, preferably 50 parts by mass or less, more preferably 48 parts by mass or less, and even more preferably 45 parts by mass or less with respect to 100 parts by mass of the base rubber. When the content of the tackifier (a) is 20 parts by mass or more, the damping property in the low strain region is further improved, and when it is 50 parts by mass or less, the damping property in the low strain region and the temperature dependence of the shear modulus are further improved.

[0055] The glass transition temperature (Tg) of the tackifier (b) is preferably 60°C or higher, more preferably 62°C or higher, still more preferably 64°C or higher, preferably 70°C or lower, more preferably 68°C or lower, and still more preferably 66°C or lower. If the glass transition temperature (Tg) of the tackifier (b) is within the above range, the effects of the present invention can be obtained more favorably.

[0056] Specific examples of the tackifier (b) include commercially available products such as Sylvatraxx 4150 manufactured by Clayton and Quintone 1920 manufactured by Nippon Zeon Co., Ltd.

[0057] The content of the tackifier (b) is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 7.5 parts by mass or more, preferably 15 parts by mass or less, more preferably 13 parts by mass or less, and still more preferably 12.5 parts by mass or less with respect to 100 parts by mass of the base rubber. If the content of the tackifier (b) is 3 parts by mass or more, the attenuation property in the low strain region and the temperature dependence of the shear modulus are further improved, and if it is 15 parts by mass or less, the attenuation property in the low strain region is further improved.

[0058] The mass ratio ((a) / (b)) of the tackifier (a) to the tackifier (b) is preferably 1.5 or more, more preferably 3 or more, still more preferably 4 or more, preferably 16 or less, more preferably 10 or less, and still more preferably 8 or less. If the mass ratio ((a) / (b)) is within the above range, the effects of the present invention can be obtained more favorably.

[0059] The glass transition temperature (Tg a ) of the tackifier (a) and the glass transition temperature (Tg b ) of the tackifier (b), and the difference (Tg b - Tg a) is preferably 10°C or higher, more preferably 12°C or higher, still more preferably 15°C or higher, preferably 30°C or lower, more preferably 28°C or lower, and still more preferably 25°C or lower. If the difference in glass transition temperature (Tg b -Tg a ) is within the above range, the effects of the present invention can be obtained more favorably.

[0060] The tackifier (c) is one selected from the group consisting of petroleum resins, terpene resins, coumarone resins, and styrene resins, having a glass transition temperature of less than 40°C, or having a glass transition temperature of more than 50°C and less than 60°C, or having a glass transition temperature of more than 70°C. Among these, it is particularly preferable to use those having a glass transition temperature of less than 40°C.

[0061] Specific examples of the tackifier (c) include commercially available products such as Petcol 130 manufactured by Tosoh Corporation, Struktol 40MS manufactured by Struktol Company, FTR8100 and FTR6100 manufactured by Mitsui Chemicals, Inc.

[0062] The content of the tackifier (c) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and still more preferably 40 parts by mass or less with respect to 100 parts by mass of the base rubber. If the content of the tackifier (c) is within the above range, the effects of the present invention can be obtained more favorably.

[0063] When the tackifier (c) is contained, the total content ratio of the tackifiers (a) and (b) in the tackifier ((a)+(b)+(c)) is preferably 40% by mass or more, more preferably 50% by mass or more, preferably 95% by mass or less, and more preferably 90% by mass or less. If the total content ratio of the tackifiers (a) and (b) is within the above range, the effects of the present invention can be obtained more favorably.

[0064] The total amount of the tackifier ((a) + (b) + (c)) is preferably 60 parts by mass or more, more preferably 62 parts by mass or more, still more preferably 65 parts by mass or more, preferably 100 parts by mass or less, more preferably 95 parts by mass or less, and still more preferably 80 parts by mass or less with respect to 100 parts by mass of the base rubber. If the total content of the tackifier is 60 parts by mass or more, the attenuation property in the low strain region is improved. If it is 100 parts by mass or less, the attenuation property in the low strain region and the temperature dependence of the shear modulus are improved, and the processability is also good. When the tackifiers (b) and (c) are not contained, the total amount of the tackifier is the content of the tackifier (a).

[0065] (Carbon black) The carbon black contained in the rubber composition with improved damping property of the present invention includes, for example, those produced by pyrolysis or incomplete combustion using hydrocarbons such as petroleum-based or coal-based oils and natural gas as raw materials. As the carbon black, any of furnace carbon black, thermal carbon black, channel carbon black, and acetylene black classified by the production method may be used.

[0066] Examples of the carbon black include furnace carbon blacks such as SAF (Super Abrasion Furnace Black), ISAF (Intermediate Super Abrasion Furnace Black), IISAF (Intermediate ISAF), HAF (High Abrasion Furnace Black), MAF (Medium Abrasion Furnace Black), FEF (Fast Extruding Furnace Black), SRF (Semi-Reinforcing Furnace Black), GPF (General Purpose Furnace Black), FF (Fine Furnace Black), and CF (Conductive Furnace Black); thermal carbon blacks such as FT (Fine Thermal black) and MT (Medium Thermal Black); channel carbon blacks such as EPC (Easy Processing Channel Black) and MPC (Medium Processing Channel Black); and acetylene black. The carbon black may be used alone or in combination of two or more kinds.

[0067] Specific examples of the carbon black include commercially available products such as the Seast series (e.g., Seast 3) manufactured by Tokai Carbon Co., Ltd.

[0068] The arithmetic mean particle diameter (primary particle diameter) of the carbon black is preferably 15 nm or more, more preferably 20 nm or more, still more preferably 25 nm or more, preferably 100 nm or less, more preferably 80 nm or less, and still more preferably 60 nm or less. If the arithmetic mean particle diameter of the carbon black is within the above range, the processability and the attenuation performance in the low strain region will be better. The arithmetic mean particle diameter can be determined, for example, by measuring the diameters of the carbon black particles in an electron micrograph and calculating their arithmetic mean value.

[0069] The nitrogen adsorption specific surface area of the carbon black is preferably 30 m 2 / g or more, more preferably 50 m 2 / g or more, still more preferably 70 m 2 / g or more, and preferably 150 m 2 / g or less, more preferably 130 m 2 / g or less, still more preferably 110 m 2 / g or less. If the nitrogen adsorption specific surface area of the carbon black is within the above range, the processability and the attenuation performance in the low strain region will be better. The nitrogen adsorption specific surface area can be measured, for example, by a gas phase adsorption method using nitrogen gas as the adsorbed gas.

[0070] The iodine adsorption amount of the carbon black is preferably 30 mg / g or more, more preferably 50 mg / g or more, still more preferably 70 mg / g or more, preferably 150 mg / g or less, more preferably 130 mg / g or less, and still more preferably 110 mg / g or less. If the iodine adsorption amount of the carbon black is within the above range, the processability and the attenuation performance in the low strain region will be better. The iodine adsorption amount can be measured, for example, in accordance with JIS K6217-1.

[0071] The DBP (dibutyl phthalate) absorption amount of the carbon black is preferably 40 cm 3 / 100 g or more, more preferably 60 cm 3 / 100 g or more, still more preferably 80 cm 3 / 100 g or more, and preferably 150 cm 3 / 100 g or less, more preferably 140 cm 3 / 100 g or less, still more preferably 130 cm 3It is more preferably below 100 g / 100 g. If the DBP absorption amount of the carbon black is within the above range, the processability and the attenuation performance in the low strain region will be better. The DBP absorption amount can be measured, for example, in accordance with the oil absorption A method of JIS K6217-4.

[0072] The content of the carbon black is preferably 100 parts by mass or more, more preferably 110 parts by mass or more, still more preferably 120 parts by mass or more, preferably 160 parts by mass or less, more preferably 150 parts by mass or less, and still more preferably 140 parts by mass or less with respect to 100 parts by mass of the base rubber. If the content of the carbon black is 100 parts by mass or more, the discharge of the rubber composition after kneading becomes easier, and the attenuation property in the low strain region of the attenuation member is improved. If it is 160 parts by mass or less, the kneading of the rubber composition becomes easy and the processability is good.

[0073] (Silica) The silica contained in the rubber composition of the present invention includes, for example, synthetic silica having a porous structure obtained by chemically reacting mainly silica sand as a raw material.

[0074] Any of wet-process silica and dry-process silica classified by the production method may be used for the silica. Further, wet-process silica includes precipitation method silica and gel method silica depending on the reaction conditions. Any of these precipitation method silica or gel method silica may be used. Among these, it is particularly preferable to use precipitation method silica having relatively large primary particles and a soft agglomerated structure.

[0075] Specific examples of the silica include commercially available products such as the Nipsil (registered trademark) series (for example, Nipsil VN3) manufactured by Tosoh Silica Corporation.

[0076] The BET specific surface area of the silica is preferably 130 m 2 / g or more, more preferably 150 m 2 / g or more, and still more preferably 170 m 2More preferably, it is 300 m / g or more, 2 preferably, it is 290 m / g or less, 2 more preferably, it is 280 m / g or less, 2 even more preferably, it is 270 m / g or less. When the BET specific surface area of the silica is within the above range, the processability and the attenuation performance in the low strain region are better. The BET specific surface area is a value measured by the gas phase adsorption method using nitrogen gas as the adsorbed gas.

[0077] The content of the silica is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less, based on 100 parts by mass of the base rubber. When the content of the silica is 5 parts by mass or more, the effect of improving the attenuation property in the low strain region by the silica is exhibited. When it is 60 parts by mass or less, the kneading of the rubber composition becomes easy and the processability is good.

[0078] The mass ratio of the carbon black to the silica (carbon black / silica) is preferably 2 or more, more preferably 3 or more, even more preferably 5 or more, preferably 20 or less, more preferably 18 or less, and even more preferably 15 or less. When the mass ratio (carbon black / silica) is within the above range, the effects of the present invention can be obtained better.

[0079] The total content of the carbon black and the silica is preferably 110 parts by mass or more, more preferably 120 parts by mass or more, even more preferably 130 parts by mass or more, preferably 200 parts by mass or less, more preferably 190 parts by mass or less, and even more preferably 180 parts by mass or less, based on 100 parts by mass of the base rubber. When the total content of the carbon black and the silica is within the above range, the effects of the present invention can be obtained better.

[0080] (Vulcanizing agent) The damping rubber composition of the present invention preferably further contains a vulcanizing agent.

[0081] As the vulcanizing agent, it is preferable to use a sulfur-based vulcanizing agent. Examples of the sulfur-based vulcanizing agent include powdered sulfur, oil-treated powdered sulfur, precipitated sulfur, colloidal sulfur, dispersible sulfur, and the like. These sulfur-based vulcanizing agents may be used alone or in combination of two or more.

[0082] Specific examples of the vulcanizing agent include commercially available products such as 5% oil-treated powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

[0083] The content of the vulcanizing agent is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, still more preferably 1.0 parts by mass or more, preferably 3.0 parts by mass or less, more preferably 2.5 parts by mass or less, and still more preferably 2.0 parts by mass or less, based on 100 parts by mass of the base rubber. If the content of the vulcanizing agent is within the above range, good vulcanizability can be achieved while suppressing the occurrence of bloom. When using, for example, oil-treated powdered sulfur or dispersible sulfur as the vulcanizing agent, the content is the content of sulfur itself as the active ingredient contained therein.

[0084] (Vulcanization accelerator) The damping rubber composition of the present invention preferably further contains a vulcanization accelerator.

[0085] Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole (MBT) and 2-benzothiazolyldisulfide (MBTS); dithiocarbamate-based accelerators such as zinc dimethyldithiocarbamate (ZnMDC), zinc diethyldithiocarbamate (ZnEDC), and zinc dibutyldithiocarbamate (ZnBDC); thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), tetrabutylthiuram disulfide (TBTD), and tetrabenzylthiuram disulfide (TBzTD); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazylsulfenamide (CBS), N-tert-butyl-2-benzothiazolesulfenamide (TBBS), N-oxydiethylene-2-benzothiazolesulfenamide (OBS), and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine (DPG), diorthotolylguanidine, and orthotolylbiguanidine. These may be used alone or in combination of two or more.

[0086] Specific examples of the vulcanization accelerator include, for example, the Accel (registered trademark) series manufactured by Kawaguchi Chemical Industry Co., Ltd. (e.g., Accel CZ, Accel TET), the Nocceler (registered trademark) series manufactured by Ouchi Shinsei Chemical Co., Ltd., and the like.

[0087] The content of the vulcanization accelerator is preferably 0.3 part by mass or more, more preferably 0.4 part by mass or more, further preferably 0.5 part by mass or more, preferably 2.0 parts by mass or less, more preferably 1.8 parts by mass or less, and further preferably 1.5 parts by mass or less, based on 100 parts by mass of the base rubber. If the content of the vulcanization accelerator is within the above range, good vulcanization acceleration can be achieved while suppressing the occurrence of bloom.

[0088] (Other components) In addition to the above components, the damping rubber composition of the present invention may further contain various additives that can be used in damping rubber compositions, such as plasticizers, vulcanization aids, anti-aging agents, tackifiers other than the above-mentioned tackifiers (a), (b), (c), fillers other than the above-mentioned carbon black and silica, softeners, etc., as long as the object of the present invention is not impaired, and they may be appropriately selected and contained.

[0089] [Plasticizer] Examples of the plasticizer include orthophosphate plasticizers such as trimethyl phosphate (TMP), triethyl phosphate (TEP), tributyl phosphate (TBP), tris(2-ethylhexyl) phosphate (TOP), triphenyl phosphate (TPP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), and cresyl diphenyl phosphate (CDP); phthalate plasticizers such as dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and bis(2-ethylhexyl) phthalate (DOP); adipic acid ester plasticizers such as dibutyl adipate (DBA), diisobutyl adipate (DIBA), bis(2-ethylhexyl) adipate (DOA), diisononyl adipate (DINA), diisodecyl adipate (DIDA), bis[2-(2-butoxyethoxy)ethyl] adipate (BXA-N), and bis[2-(2-butoxyethoxy)ethyl] adipate (BXA-R); sebacic acid ester plasticizers such as dibutyl sebacate (DBS) and bis(2-ethylhexyl) sebacate (DOS); and ricinoleic acid ester plasticizers such as methyl acetyl ricinoleate (MAR-N). These plasticizers may be used alone or in combination of two or more.

[0090] Specific examples of the plasticizer include, for example, plasticizers for various rubber applications manufactured by Daihachi Chemical Industry Co., Ltd.

[0091] The viscosity (at 25°C) of the plasticizer is preferably 5 mPa·s or more, more preferably 8 mPa·s or more, even more preferably 10 mPa·s or more, preferably 25 mPa·s or less, more preferably 22 mPa·s or less, and even more preferably 20 mPa·s or less. If the viscosity of the plasticizer is within the above range, the processability of the rubber composition will be better. The viscosity of the plasticizer can be measured, for example, at 25°C by the "kinematic viscosity test method" specified in JIS K2283:2000.

[0092] The content of the plasticizer is preferably 15 parts by mass or more, more preferably 18 parts by mass or more, even more preferably 20 parts by mass or more, preferably 35 parts by mass or less, more preferably 32 parts by mass or less, and even more preferably 30 parts by mass or less with respect to 100 parts by mass of the base rubber. If the content of the plasticizer is 15 parts by mass or more, the kneading of the rubber composition becomes easier, and if it is 35 parts by mass or less, the discharge of the rubber composition after kneading becomes easier.

[0093] [Vulcanization accelerator] Examples of the vulcanization accelerator include metal compounds such as zinc oxide and fatty acids such as stearic acid, oleic acid, and cottonseed fatty acid. These vulcanization accelerators may be used alone or in combination of two or more.

[0094] Specific examples of the vulcanization accelerator include, for example, commercially available products such as two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. and Camellia manufactured by NOF Corporation.

[0095] The content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, preferably 10 parts by mass or less, more preferably 9 parts by mass or less, and even more preferably 8 parts by mass or less with respect to 100 parts by mass of the base rubber. If the content of the vulcanization accelerator is within the above range, the vulcanization property of the rubber composition will be better.

[0096] Also, it is also preferable to use a metal compound and a fatty acid in combination as a vulcanization aid. In this case, the mass ratio of the metal compound to the fatty acid (metal compound / fatty acid) is preferably 0.5 or more, more preferably 1 or more, even more preferably 1.5 or more, preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less. If the mass ratio of the metal compound to the fatty acid is within the above range, the vulcanization property of the rubber composition will be further improved.

[0097] [Antioxidant] Examples of the antioxidant include various antioxidants such as benzimidazole-based, quinone-based, polyphenol-based, and amine-based antioxidants. These antioxidants may be used alone or in combination of two or more. Among these, benzimidazole-based antioxidants and quinone-based antioxidants are preferable, and it is more preferable to use a benzimidazole-based antioxidant and a quinone-based antioxidant in combination.

[0098] Specific examples of the benzimidazole-based antioxidant include, for example, commercially available products such as No Crack (registered trademark) series manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. (e.g., No Crack MB). Specific examples of the quinone-based antioxidant include, for example, Antigen FR [aromatic ketone-amine condensate] manufactured by Maruishi Chemical Co., Ltd.

[0099] The content of the antioxidant is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 2 parts by mass or more, preferably 8 parts by mass or less, more preferably 6 parts by mass or less, and even more preferably 5 parts by mass or less with respect to 100 parts by mass of the base rubber. If the content of the antioxidant is within the above range, the antioxidant effect of the rubber composition will be good.

[0100] When a benzimidazole-based antioxidant and a quinone-based antioxidant are used in combination as the antioxidant, the mass ratio thereof (benzimidazole-based / quinone-based) is preferably 0.2 or more, more preferably 0.5 or more, still more preferably 0.8 or more, preferably 5 or less, more preferably 4 or less, and still more preferably 2 or less. If the mass ratio (benzimidazole-based / quinone-based) is within the above range, the antioxidant effect of the rubber composition will be better.

[0101] [Other tackifiers] In addition to the tackifiers (a), (b), and (c), the damping rubber composition of the present invention may further contain other tackifiers (d).

[0102] The tackifier (d) is not particularly limited as long as it is different from one kind of tackifier ((a), (b), (c)) selected from the group consisting of petroleum resins, terpene resins, coumarone resins, and styrene resins. As the tackifier (d), a rosin-based tackifier is preferable. Examples of the rosin-based tackifier include rosin-based resins such as rosin ester, hydrogenated rosin ester, disproportionated rosin ester, and polymerized rosin ester. These tackifiers (d) may be used alone or in combination of two or more.

[0103] Specific examples of the rosin-based resin include commercially available products such as Pink Crystal (registered trademark) series (for example, Pink Crystal KR-85) manufactured by Arakawa Chemical Industries, Ltd.

[0104] The softening point (ring and ball method) of the tackifier (d) is preferably 50°C or higher, more preferably 60°C or higher, still more preferably 70°C or higher, preferably 120°C or lower, more preferably 110°C or lower, and still more preferably 100°C or lower. If the softening point of the tackifier (d) is within the above range, the effects of the present invention can be obtained more favorably. The softening point of the tackifier can be measured, for example, in accordance with JIS K-2207 (1996) (ring and ball method).

[0105] The content of the tackifier (d) is preferably 5 parts by mass or more, more preferably 6 parts by mass or more, still more preferably 8 parts by mass or more, preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and still more preferably 15 parts by mass or less with respect to 100 parts by mass of the base rubber. If the content of the tackifier (d) is within the above range, the effects of the present invention can be obtained more favorably.

[0106] The mass ratio ((a) + (b) + (c)) / (d) of the above-described tackifiers ((a) + (b) + (c)) and the tackifier (d) is preferably 4 or more, more preferably 5 or more, still more preferably 6 or more, preferably 15 or less, more preferably 12 or less, and still more preferably 10 or less. If the mass ratio ((a) + (b) + (c)) / (d) is within the above range, the effects of the present invention can be obtained more favorably.

[0107] [Filler other than carbon black and silica] Examples of the filler other than carbon black and silica include inorganic fillers such as calcium carbonate, magnesium carbonate, barium sulfate, talc, and clay. These fillers may be used alone or in combination of two or more.

[0108] The damping rubber composition of the present invention can be prepared, for example, by kneading a base rubber, a tackifier, carbon black, silica, a vulcanizing agent, a vulcanization accelerator, and other components added as necessary. The kneading method is not particularly limited, and for example, it may be carried out using a known kneader such as a closed kneader, kneading rolls, a Banbury mixer, or a kneader.

[0109] <Damping rubber> The present invention includes a damping rubber obtained by curing the damping rubber composition of the present invention. The damping rubber of the present invention can be obtained, for example, by pressing the kneaded damping rubber composition under the conditions of 130°C to 170°C for 20 minutes to 10 hours to simultaneously perform molding and vulcanization.

[0110] The damping rubber of the present invention is excellent in damping property in a low strain region such as wind-induced vibration, and has a small temperature dependence of the damping property and the shear elastic modulus in the low strain region. For example, it can be suitably used as a vibration-proof material for absorbing vibrations in a low strain region such as wind-induced vibration.

[0111] The damping rubber of the present invention preferably has an equivalent damping constant heq(23°C) measured under the conditions of a temperature of 23°C and a strain of 2% of 0.25 or more, more preferably 0.28 or more, and even more preferably 0.30 or more. If the equivalent damping constant heq(23°C) is 0.25 or more, the damping property of the damping rubber will be good.

[0112] The damping rubber of the present invention preferably has a ratio (heq(10°C) / heq(30°C)) of the equivalent damping constant heq(10°C) measured under the conditions of a temperature of 10°C and a strain of 2% to the equivalent damping constant heq(30°C) measured under the conditions of a temperature of 30°C and a strain of 2% of 1.60 or less, more preferably 1.40 or less, and even more preferably 1.20 or less. If the ratio (heq(10°C) / heq(30°C)) is 1.60 or less, the low-temperature dependence of the damping property of the damping rubber becomes good. The lower limit of the ratio (heq(10°C) / heq(30°C)) is not particularly limited, but is preferably 0.80, more preferably 0.90, and even more preferably 0.95.

[0113] The damping rubber of the present invention preferably has a ratio (Geq(10°C) / Geq(30°C)) of the equivalent shear modulus Geq(10°C) measured under the conditions of a temperature of 10°C and a strain of 2% to the equivalent shear modulus Geq(30°C) measured under the conditions of a temperature of 30°C and a strain of 2% of 1.60 or less, more preferably 1.50 or less, and even more preferably 1.40 or less. If the ratio (Geq(10°C) / Geq(30°C)) is 1.60 or less, the low-temperature dependence of the shear modulus of the damping rubber becomes good. The lower limit of the ratio (Geq(10°C) / Geq(30°C)) is not particularly limited, but is preferably 0.80, more preferably 0.90, and even more preferably 0.95.

[0114] <Viscoelastic damper> The present invention includes a viscoelastic damper provided with the damping rubber of the present invention as a damping member. The viscoelastic damper of the present invention is excellent in damping property in a low-strain region such as wind-induced vibration, and has small temperature dependence of damping property and shear modulus in the low-strain region. For example, it can be suitably used as a viscoelastic damper for absorbing vibration in a low-strain region such as wind-induced vibration (particularly a viscoelastic damper installed in a building).

Examples

[0115] Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to the following examples, and any changes and embodiments within the scope not departing from the gist of the present invention are all included in the scope of the present invention.

[0116] [Evaluation method] <Processability test> Using a closed kneader, the components of the rubber composition were kneaded. Those that could be smoothly kneaded from kneading to discharge without problems were rated as "○", those that were a little difficult but possible were rated as "△", and those that could not be kneaded were rated as "×", and the processability was evaluated. Those rated as "○" or "△" were considered qualified.

[0117] <Displacement test> (Preparation of test specimens) After each rubber composition was extruded into a sheet shape and punched out, a flat plate 1 (thickness 8 mm × length 40 mm × width 40 mm) with a rectangular planar shape as shown in FIG. 1 was formed. Next, rectangular flat steel plates 2 with a thickness of 6 mm × length 44 mm × width 44 mm were stacked on both the front and back surfaces of this flat plate 1 via a vulcanization adhesive to form a laminate. Then, while applying pressure to the above laminate in the stacking direction, it was heated to 140°C to crosslink the rubber composition forming the flat plate 1 and to vulcanization-adhere the flat plate 1 to the two steel plates 2, thereby producing a test specimen 3 as a model of the damping member.

[0118] (Displacement tests at 23°C, 10°C, and 30°C) Two test specimens 3 were prepared as shown in Fig. 2(a), and the two test specimens 3 were each fixed to a single central fixing jig 4 with bolts via one steel plate 2. At the same time, one left - right fixing jig 5 was fixed to the other steel plate 2 of each of the two test specimens 3 with bolts. Next, the central fixing jig 4 was fixed to the upper fixing arm 6 of a testing machine (not shown) with bolts via a joint 7, and the two left - right fixing jigs 5 were fixed to the movable platen 8 on the lower side of the testing machine with bolts via joints 9. Note that the two test specimens 3 were fixed as described above with two sides of the flat plate 1 that are parallel to each other aligned parallel to the following displacement direction. Next, taking the operations in the following (I) and (II) as one cycle, the relationship between the displacement amount (mm) in the direction orthogonal to the thickness direction of the flat plate 1 and the load (N) when the flat plate 1 was repeatedly deformed by strain, that is, vibrated, was obtained as a hysteresis loop H (see Fig. 3). (I): The movable platen 8 was displaced so as to be pushed up in the direction of the fixing arm 6 as shown by the white arrow in Fig. 2(a), and the flat plate 1 was deformed by strain in the direction orthogonal to the thickness direction as shown in Fig. 2(b). (II): From the above state, the movable platen 8 was displaced so as to be pulled down in the direction opposite to the direction of the fixing arm 6 as shown by the white arrow in Fig. 2(b) to return to the state shown in Fig. 2(a).

[0119] The measurement was carried out by performing the operations in the above (I) and (II) three cycles each under environments of temperature 23°C, 10°C, and 30°C, and the values of the third cycle were obtained. The maximum displacement amount in each cycle was set such that the displacement amount in the direction orthogonal to the thickness direction of the two steel plates 2 sandwiching the flat plate 1 was 2% of the thickness of the flat plate 1.

[0120] From the hysteresis loop H in Fig. 3 obtained by the measurement, the equivalent shear modulus Geq (N / mm 2 ) was obtained by the following formula (1).

[0121]

Equation

[0122] Wherein, Keq (N / mm) is the slope of the straight line L1 shown by the thick solid line in FIG. 3 connecting the maximum displacement point and the minimum displacement point of the hysteresis loop H, T (mm) is the thickness of the flat plate 1, and A (mm 2 ) is the cross-sectional area of the flat plate 1.

[0123] Also, from the hysteresis loop H in FIG. 3, the equivalent damping constant heq was obtained by the following formula (2).

[0124]

Equation

[0125] Wherein, ΔW is the amount of absorbed energy represented by the total surface area of the hysteresis loop H shown hatched in FIG. 3, and W is the elastic strain energy represented by the surface area of the triangular region surrounded by the straight line L1, the horizontal axis of the graph, and the perpendicular line L2 dropped from the intersection of the straight line L1 and the hysteresis loop H to the horizontal axis of the graph in the same figure.

[0126] (Damping property) The equivalent damping constant heq (23°C) measured in an environment at a temperature of 23°C was used as an index of the damping property. The larger such an equivalent damping constant heq (23°C) is, the better the damping property is indicated. The equivalent damping constant heq (23°C) was shown as a relative value with the heq (23°C) of Comparative Example 1 being 1.00. A relative value of 0.70 or more was rated as "〇" (qualified), and a relative value less than 0.70 was rated as "×" (unqualified).

[0127] (Temperature dependence of damping property) The ratio of the equivalent attenuation constant heq(10°C) measured in an environment at a temperature of 10°C to the equivalent attenuation constant heq(30°C) measured in an environment at a temperature of 30°C, i.e., heq(10°C) / heq(30°C), was used as an index of the temperature dependence of the attenuation property. The closer such a ratio is to 1, the smaller the temperature dependence of the attenuation property. The temperature dependence of the attenuation property (heq(10°C) / heq(30°C)) was shown as a relative value with the (heq(10°C) / heq(30°C)) of Comparative Example 1 being 1.00. A relative value of 1.10 or less was rated as "〇" (qualified), and those greater than 1.10 were rated as "×" (unqualified).

[0128] (Temperature dependence of shear modulus) The ratio of the equivalent shear modulus Geq(10°C) measured in an environment at a temperature of 10°C to the equivalent shear modulus Geq(30°C) measured in an environment at a temperature of 30°C, i.e., Geq(10°C) / Geq(30°C), was used as an index of the temperature dependence of the shear modulus. The closer such a ratio is to 1, the smaller the temperature dependence of the shear modulus. The temperature dependence of the shear modulus (Geq(10°C) / Geq(30°C)) was shown as a relative value with the (Geq(10°C) / Geq(30°C)) of Comparative Example 1 being 1.00. A relative value of 0.95 or less was rated as "〇" (qualified), and those greater than 0.95 were rated as "×" (unqualified).

[0129] <Overall evaluation> When the evaluation results of processability, attenuation property, and the temperature dependence of attenuation property and shear modulus were all "qualified", the overall evaluation was rated as "〇", and when any one of the evaluation results of processability, attenuation property, and the temperature dependence of attenuation property and shear modulus was "unqualified", the overall evaluation was rated as "×".

[0130] The components of each formulation shown in Tables 1 and 2 were kneaded using a closed kneader to prepare a rubber composition.

[0131]

Table 1

[0132]

Table 2

[0133] Each component in Tables 1 and 2 is as follows. IR2200: Polyisoprene rubber manufactured by Nippon Zeon Co., Ltd. (trade name: Nipol IR2200, Mooney viscosity (ML 1+4 (100 °C)): 82) BR130B: Polybutadiene rubber manufactured by Ube Industries, Ltd. (trade name: UBEPOL BR130B, Mooney viscosity (ML 1+4 (100 °C)): 26) Coumarone resin: Coumarone-indene-styrene copolymer resin manufactured by Nittosei Chemical Co., Ltd. (trade name: Nittoresin Coumarone G-90, Tg: 43 °C) Terpene resin: Polypentene resin manufactured by Kraton Corporation (trade name: Sylvatraxx 4150, Tg: 65 °C) Petroleum resin: C9-based (aromatic-based) petroleum resin manufactured by Tosoh Corporation (trade name: Petcol 130, Tg: 74 °C) Styrene resin: Styrene-based monomer homopolymer resin manufactured by Mitsui Chemicals, Inc. (trade name: FTR8100, Tg: 35 °C) Carbon black: Manufactured by Tokai Carbon Co., Ltd. (trade name: Seast 3, arithmetic mean particle diameter: 28 nm, nitrogen adsorption specific surface area: 79 m 2 / g, iodine adsorption amount: 80 mg / g, DBP absorption amount: 101 cm 3 / 100 g) phos) phate, viscosity (25 °C): 12 mPa·s) Silica: Manufactured by Tosoh Silica Corporation (trade name: Nipsil VN3, precipitated silica) Vulcanizing agent: 5% oil-treated powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Accelerator CZ: Sulfenamide-based vulcanization accelerator manufactured by Kawaguchi Chemical Industry Co., Ltd. Accelerator TET: Thiuram-based vulcanization accelerator manufactured by Kawaguchi Chemical Industry Co., Ltd. Plasticizer: Orthophosphoric acid ester manufactured by Daihachi Chemical Industry Co., Ltd. (trade name: TOP, chemical name: tris(2-ethylhexyl) phosphate) Rosin-based adhesive: Ultra-light-colored rosin manufactured by Arakawa Chemical Industries, Ltd. (trade name: Pine Crystal KR-85, softening point (ring method): 80 - 87 °C) No-crack MB: A benzimidazole-based antioxidant manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Antigen FR: A quinone-based antioxidant manufactured by Maruishi Chemical Co., Ltd. Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Camellia manufactured by NOF Corporation

[0134] As is clear from the results in Tables 1 and 2, a damping rubber composition containing a base rubber, tackifier, carbon black, silica, vulcanizing agent, and vulcanization accelerator, wherein the base rubber contains a polyisoprene-based rubber and a polybutadiene-based rubber, the content of the polybutadiene-based rubber in the base rubber is 20% by mass or more and 60% by mass or less, the tackifier is at least one selected from the group consisting of petroleum resins, terpene resins, coumarone resins, and styrene resins, the content of the tackifier is 60 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the base rubber, the content of the carbon black is 100 parts by mass or more and 160 parts by mass or less with respect to 100 parts by mass of the base rubber, and the content of the silica is 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the base rubber. The damping rubber composition of the present invention has good processability, is excellent in damping property in a low strain region such as wind sway, and can form a damping member with small temperature dependence of damping property and shear modulus in the low strain region.

Explanation of symbols

[0135] 1: Flat plate, 2: Steel plate, 3: Specimen, 4: Central fixing jig, 5: Left and right fixing jigs, 6: Fixing arm, 7: Joint, 8: Movable plate, 9: Joint, H: Hysteresis loop, L1: Straight line, L2: Perpendicular line, W: Elastic strain energy, ΔW: Amount of absorbed energy, Keq: Slope of straight line L1

[0136] A preferred embodiment (1) of the present invention is a damping rubber composition containing a base rubber, tackifier, carbon black, silica, vulcanizing agent, and vulcanization accelerator, wherein the base rubber contains a polyisoprene-based rubber and a polybutadiene-based rubber, The content rate of polybutadiene rubber in the base rubber is 20 mass% or more and 60 mass% or less, The tackifier is at least one selected from the group consisting of petroleum resins, terpene resins, coumarone resins, and styrene resins, The content of the tackifier is 60 mass parts or more and 100 mass parts or less with respect to 100 mass parts of the base rubber, The content of the carbon black is 100 mass parts or more and 160 mass parts or less with respect to 100 mass parts of the base rubber, The content of the silica is 5 mass parts or more and 60 mass parts or less with respect to 100 mass parts of the base rubber, and it is a damping rubber composition characterized by this.

[0137] A preferred embodiment (2) of the present invention is the damping rubber composition according to the above-described embodiment (1), wherein the tackifier contains a tackifier (a) having a glass transition temperature (Tg) of 40°C to 50°C, a tackifier (b) having a glass transition temperature (Tg) of 60°C to 70°C, and a tackifier (c) having a glass transition temperature (Tg) different from those of the tackifiers (a) and (b).

[0138] A preferred embodiment (3) of the present invention is the damping rubber composition according to the above-described embodiment (2), wherein the content of the tackifier (a) is 20 mass parts or more and 50 mass parts or less with respect to 100 mass parts of the base rubber, and the content of the tackifier (b) is 3 mass parts or more and 15 mass parts or less with respect to 100 mass parts of the base rubber.

[0139] A preferred embodiment (4) of the present invention is the damping rubber composition according to any one of the above-described embodiments (1) to (3), further containing a rosin-based tackifier.

[0140] A preferred embodiment (5) of the present invention is a damping rubber obtained by curing the damping rubber composition according to any one of the above-described embodiments (1) to (4).

[0141] A preferred aspect (6) of the present invention is a viscoelastic damper including a damping member obtained by curing the damping rubber composition according to any one of the aspects (1) to (4).

Claims

1. A damping rubber composition containing a base rubber, a tackifier, carbon black, silica, a vulcanizing agent, and a vulcanization accelerator, wherein the base rubber contains a polyisoprene rubber and a polybutadiene rubber, the content of the polybutadiene rubber in the base rubber is 20% by mass or more and 60% by mass or less, the tackifier is at least one selected from the group consisting of a petroleum resin, a terpene resin, a coumarone resin, and a styrene resin, the content of the tackifier is 60 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the base rubber, the content of the carbon black is 100 parts by mass or more and 160 parts by mass or less with respect to 100 parts by mass of the base rubber, and the content of the silica is 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the base rubber, characterized by a damping rubber composition.

2. The damping rubber composition according to claim 1, wherein the tackifier contains a tackifier (a) having a glass transition temperature (Tg) of 40°C to 50°C, a tackifier (b) having a glass transition temperature (Tg) of 60°C to 70°C, and a tackifier (c) having a glass transition temperature (Tg) different from those of the tackifiers (a) and (b).

3. The damping rubber composition according to claim 2, wherein the content of the tackifier (a) is 20 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the base rubber, and the content of the tackifier (b) is 3 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the base rubber.

4. The damping rubber composition according to claim 1, further containing a rosin-based tackifier.

5. A damping rubber obtained by curing the damping rubber composition according to any one of claims 1 to 4.

6. A viscoelastic damper comprising a damping member obtained by curing the damping rubber composition according to any one of claims 1 to 4.

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