Damping rubber composition and viscoelastic damper

Abstract

To provide a damping rubber composition which can form a damping member with excellent processability, high damping performance, and small temperature dependence of shear modulus.SOLUTION: A damping rubber composition comprises (a) a base rubber, (b) a filler, and (c) a tackifier, wherein the base rubber (a) contains styrene-butadiene rubber, the styrene-butadiene rubber has a glass transition temperature of -55°C or lower, the content of the filler (b) is 120 pts.mass or more and 170 pts.mass or less per 100 pts.mass of the base rubber (a), and the content of the tackifier (c) is 40 pts.mass or more and 80 pts.mass or less per 100 pts.mass of the base rubber (a).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 technology]

[0002] Conventionally, means for absorbing vibration energy generated by earthquakes, traffic vibrations, wind sway, etc. have been installed in buildings such as houses and buildings, bridges, etc. One such means is a viscoelastic damper equipped with a damping member (viscoelastic material). Viscoelastic dampers are relatively inexpensive and have excellent vibration damping performance against strong vibrations such as those caused by major earthquakes, and therefore are widely used as means for providing seismic isolation, vibration control, vibration damping, and vibration isolation. Various high-damping rubber compositions have been proposed for forming damping members.

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

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

[0005] Patent Document 3 discloses a silica-blended 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) a butyl-based 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] Japanese Patent Application Laid-Open No. 2003-003014 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-063425 [Patent Document 3] Japanese Patent Application Publication No. 07-041603 [Patent Document 4] Japanese Patent Application Laid-Open No. 2011-190397 Summary of the Invention [Problem to be solved by the invention]

[0008] Damping materials have a high temperature dependency on their damping performance, and their damping performance tends to fluctuate significantly, especially between low-temperature environments such as around 0°C and high-temperature environments such as around 40°C. However, in addition to being required to have excellent damping properties, damping materials are also required to have low temperature dependency of the shear modulus from high to low temperatures (for example, 0°C to 40°C) in consideration of environmental conditions.

[0009] Here, in damping rubber compositions, methods for increasing the damping rate (heq) include blending particulate carbon and blending tackifiers such as rosin derivatives. However, rubber compositions blended with particulate carbon or rosin derivatives did not have sufficient damping properties and the shear modulus was highly temperature-dependent. Furthermore, when isoprene rubber is used as the base rubber, isoprene rubber has high crystallinity and tends to harden at low temperatures even when it has a low glass transition temperature, and the shear modulus of the rubber composition tends to be highly temperature-dependent.

[0010] Good processability is always desired because it improves productivity, reduces energy consumption required for production, and leads to a reduction in production costs.

[0011] The present invention has been made in consideration of the above circumstances, and aims to provide a damping rubber composition that has good processability, high damping properties, and can be used to form a damping member with a small temperature dependency of shear modulus. Another object of the present invention is to provide a viscoelastic damper including a damping member formed by curing the damping rubber composition. [Means for solving the problem]

[0012] The damping rubber composition of the present invention, which has been able to solve the above-mentioned problems, contains (a) a base rubber, (b) a filler, and (c) a tackifier, wherein the (a) base rubber contains styrene-butadiene rubber, and the glass transition temperature of the styrene-butadiene rubber is −55° C. or lower, the content of the (b) filler is 120 parts by mass or more and 170 parts by mass or less per 100 parts by mass of the (a) base rubber, and the content of the (c) tackifier is 40 parts by mass or more and 80 parts by mass or less per 100 parts by mass of the (a) base rubber.

[0013] The damping rubber composition has improved damping performance due to the interaction between (a) base rubber, (b) filler, and (c) tackifier. In addition, by blending styrene-butadiene rubber having a glass transition temperature of -55°C or lower as the base rubber (a), the damping member has less fluctuation in stiffness in low-temperature environments and less temperature dependency from high to low temperatures (e.g., 0°C to 40°C). [Effects of the Invention]

[0014] According to the present invention, a damping rubber composition can be obtained that has good processability, high damping properties, and can be used to form a damping member having a shear modulus that is little dependent on temperature. Also, according to the present invention, a viscoelastic damper can be obtained that has excellent damping properties and a shear modulus that is little dependent on temperature. [Brief explanation of the drawings]

[0015] [Figure 1]FIG. 2 is an exploded perspective view showing a test specimen as a model of a damping member prepared to evaluate the damping performance of the damping member using the rubber compositions of the examples and comparative examples of the present invention. [Figure 2] FIG. 2 is a diagram illustrating an outline of a testing machine for determining the relationship between the amount of displacement and the load by displacing the test specimen. [Figure 3] 4 is a graph showing an example of a hysteresis loop showing the relationship between the displacement and the load, obtained by displacing a test specimen using the testing machine. DETAILED DESCRIPTION OF THE INVENTION

[0016] <Dampening Rubber Composition> The damping rubber composition of the present invention comprises (a) a base rubber, (b) a filler, and (c) a tackifier, wherein the (a) base rubber comprises styrene-butadiene rubber, and the glass transition temperature of the styrene-butadiene rubber is −55° C. or lower, the content of the (b) filler is 120 parts by mass or more and 170 parts by mass or less per 100 parts by mass of the (a) base rubber, and the content of the (c) tackifier is 40 parts by mass or more and 80 parts by mass or less per 100 parts by mass of the (a) base rubber.

[0017] The damping rubber composition has improved damping performance due to the interaction of (a) base rubber, (b) filler, and (c) tackifier. In addition, by blending styrene-butadiene rubber having a glass transition temperature of -55°C or lower as the base rubber (a), the damping member has less fluctuation in stiffness in low-temperature environments and less temperature dependency from high to low temperatures (e.g., 0°C to 40°C).

[0018] Each component used in the damping rubber composition of the present invention will now be described.

[0019] (a) Base rubber The (a) base rubber contained in the damping rubber composition of the present invention contains (a1) styrene-butadiene rubber.

[0020] The glass transition temperature (Tg) of the (a1) styrene-butadiene rubber is preferably −55° C. or lower, more preferably −58° C. or lower, and even more preferably −60° C. or lower. If the (a1) styrene-butadiene rubber has a glass transition temperature (Tg) of −55° C. or lower, the temperature dependency of the shear modulus of the resulting damping member from high to low temperatures (e.g., 0° C. to 40° C.) becomes small. The glass transition temperature is measured in accordance with JIS K6240 (2011).

[0021] The (a1) styrene-butadiene rubber is a copolymer of styrene and 1,3-butadiene, and any crosslinkable rubber can be used. The (a1) styrene-butadiene rubber may be used alone or in combination of two or more. When two or more types of styrene-butadiene rubber are used in combination, the glass transition temperature of the mixture is determined and used as the glass transition temperature of the (a1) styrene-butadiene rubber.

[0022] The damping rubber composition may contain only (a1) styrene-butadiene rubber as (a) base rubber, or may contain other rubber components.

[0023] The content of the (a1) styrene-butadiene rubber is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, based on 100% by mass of the (a) base rubber. If the content of the (a1) styrene-butadiene rubber is 70% by mass or more, the temperature dependency of the shear modulus of the resulting damping member from high to low temperatures (e.g., 0°C to 40°C) becomes smaller.

[0024] Examples of the other rubber components include polyisoprene rubber, polybutadiene rubber, butyl rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, natural rubber, etc. These other rubber components may be used alone or in combination of two or more.

[0025] Each rubber component contained in the damping rubber composition preferably exhibits a solid state at 25° C. In other words, the base rubber (a) preferably does not contain a liquid rubber that is normally used as a softener and exhibits a liquid state at 25° C.

[0026] The glass transition temperature (Tg) of the (a) base rubber is preferably −55° C. or lower, more preferably −58° C. or lower, and even more preferably −60° C. or lower. If the (a) base rubber has a glass transition temperature (Tg) of −55° C. or lower, the temperature dependency of the shear modulus of the resulting damping member from high to low temperatures (e.g., 0° C. to 40° C.) becomes even smaller. The glass transition temperature is measured in accordance with JIS K6240 (2011).

[0027] (b) Filler The damping rubber composition contains a filler (b), and by containing the filler (b), the damping properties of the damping member are improved.

[0028] The content of the (b) filler, relative to 100 parts by mass of the (a) base rubber, is preferably 120 parts by mass or more, more preferably 130 parts by mass or more, even more preferably 140 parts by mass or more, and is preferably 170 parts by mass or less, more preferably 160 parts by mass or less, even more preferably 155 parts by mass or less. If the content of the (b) filler is 120 parts by mass or more, the damping property of the damping member is improved, and if it is 170 parts by mass or less, the rubber composition can be easily kneaded and the processability is good.

[0029] Examples of the (b) filler include inorganic fillers and carbon black. The (b) filler is not temperature dependent and can contribute to improving damping properties and moldability. The (b) filler may be used alone or in combination of two or more.

[0030] Examples of the inorganic filler include silica, calcium carbonate, magnesium carbonate, barium sulfate, talc, and clay. These inorganic fillers may be used alone or in combination of two or more. Among these, silica is preferred as the inorganic filler. Silica has a high interaction between fillers, and therefore is highly effective in improving damping properties.

[0031] ((b1) Silica) The (b1) silica may be, for example, synthetic silica having a porous structure, which is obtained by chemically reacting silica sand as a raw material. The (b1) silica may be either wet-process silica or dry-process silica, which are classified according to the production method. Wet-process silica is further divided into precipitated silica and gel-process silica, which differ depending on the reaction conditions. Either precipitated silica or gel-process silica may be used. Among these, it is particularly preferable to use precipitated silica, which has relatively large primary particles and a soft aggregate structure.

[0032] Specific examples of the (b1) silica include commercially available products such as the Nipsil (registered trademark) series (for example, Nipsil KQ) manufactured by Tosoh Silica Corporation.

[0033] The arithmetic mean particle diameter (primary particle diameter) of the (b1) silica is preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 8 nm or more, and is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less. If the arithmetic mean particle diameter of the silica is within the above range, the processability and damping performance will be improved. The arithmetic mean particle diameter can be determined, for example, by measuring the diameter of each silica particle using an electron microscope photograph and calculating the arithmetic mean value.

[0034] The BET specific surface area of ​​the (b1) silica is 130 m 2 / g or more is preferable, and 150m 2 / g or more, more preferably 170m 2 / g or more, and 300m 2 / g or less is preferable, and 290m 2 / g or less, more preferably 280m 2 / g or less. If the BET specific surface area of ​​silica is within the above range, the processability and damping performance will be better. The BET specific surface area is a value measured by a gas phase adsorption method using nitrogen gas as the adsorption gas.

[0035] When the (b1) filler contains the (b1) silica as a main component, the content of the (b1) silica is preferably 120 parts by mass or more, more preferably 130 parts by mass or more, and even more preferably 140 parts by mass or more, and is preferably 170 parts by mass or less, more preferably 160 parts by mass or less, and even more preferably 155 parts by mass or less, per 100 parts by mass of the (a) base rubber. If the (b1) silica content is 120 parts by mass or more, the effect of improving damping properties due to silica is exerted, and if it is 170 parts by mass or less, the rubber composition is easily kneaded and has good processability.

[0036] ((b2) Carbon black) The (b2) carbon black may be produced, for example, by pyrolysis or incomplete combustion of hydrocarbons such as petroleum or coal-based oils or natural gas. The carbon black may be any of furnace carbon black, thermal carbon black, channel carbon black, and acetylene black, which are classified according to the production method.

[0037] Examples of the (b2) 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 blacks may be used alone or in combination.

[0038] Specific examples of the (b2) carbon black include commercially available products such as the Seast series (for example, Seast 3) manufactured by Tokai Carbon Co., Ltd.

[0039] The arithmetic mean particle diameter (primary particle diameter) of the (b2) carbon black is preferably 15 nm or more, more preferably 20 nm or more, and even more preferably 25 nm or more, and is preferably 100 nm or less, more preferably 80 nm or less, and even more preferably 60 nm or less. If the arithmetic mean particle diameter of the (b2) carbon black is within the above range, processability and damping performance will be improved. The arithmetic mean particle diameter can be determined, for example, by measuring the diameter of each carbon black particle using an electron microscope photograph and calculating the arithmetic mean value.

[0040] The nitrogen adsorption specific surface area of ​​the (b2) carbon black is 30 m 2 / g or more is preferable, and 50m 2 / g or more, more preferably 70m 2 / g or more, and 150m 2 / g or less is preferable, and 130m 2 / g or less, more preferably 110m 2 / g or less. (b2) If the nitrogen adsorption specific surface area of ​​carbon black is within the above range, the processability and damping performance will be improved. The nitrogen adsorption specific surface area can be measured, for example, by a gas-phase adsorption method using nitrogen gas as the adsorption gas.

[0041] When the (b2) carbon black is contained as a main component of the (b) filler, the content of the (b2) carbon black is preferably 120 parts by mass or more, more preferably 130 parts by mass or more, even more preferably 140 parts by mass or more, and is preferably 170 parts by mass or less, more preferably 160 parts by mass or less, and even more preferably 155 parts by mass or less, per 100 parts by mass of the (a) base rubber. If the (b2) carbon black content is 120 parts by mass or more, the rubber composition after kneading is more easily discharged and the damping properties of the damping member are improved, while if it is 170 parts by mass or less, the rubber composition is easily kneaded and processability is improved.

[0042] (c) Tackifier The damping rubber composition contains (c) a tackifier. By containing the (c) tackifier, the damping property of the damping member is improved.

[0043] The content of the (c) tackifier is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 60 parts by mass or more, and is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 65 parts by mass or less, per 100 parts by mass of the (a) base rubber. If the content is 40 parts by mass or more, the damping property of the damping member is improved, and if it is 80 parts by mass or less, the rubber composition can be more easily discharged after kneading.

[0044] Examples of the (c) tackifier include (c1) dicyclopentadiene-based resins, (c2) coumarone-based resins, (c3) styrene-based resins, (c4) rosin resins, (c5) terpene-based resins, etc. The (c) tackifiers may be used alone or in combination of two or more.

[0045] ((c1) Dicyclopentadiene-based resin) The (c1) dicyclopentadiene-based resin is a resin containing dicyclopentadiene as the main monomer component constituting the resin skeleton (main chain), and examples thereof include polymers in which the content of dicyclopentadiene-derived units in 100% by mass of the resin is 50% by mass or more. Specific examples of dicyclopentadiene-based resins include petroleum resins produced primarily from dicyclopentadiene, which is obtained by dimerizing cyclopentadiene extracted from C5 fractions of petroleum (isoprene, 1,3-pentadiene, cyclopentene, cyclopentadiene, etc.). The dicyclopentadiene-based resin may be a hydrogenated dicyclopentadiene-based resin (hydrogenated dicyclopentadiene-based resin). The (c1) dicyclopentadiene-based resin may be used alone or in combination of two or more types.

[0046] Specific examples of the (c1) dicyclopentadiene-based resin include commercially available products such as Marucarets (registered trademark) M series (for example, Marucarets M890) manufactured by Maruzen Petrochemical Co., Ltd.

[0047] ((c2) Coumarone resin) The (c2) coumarone resin is a resin having structural units mainly derived from coumarone, and examples thereof include coumarone resin, coumarone-indene resin, copolymer resin mainly composed of coumarone, indene, and styrene, etc. These (c2) coumarone resins may be used alone or in combination of two or more.

[0048] Specific examples of the (c2) coumarone-based resin include commercially available products such as the Knit Resin (registered trademark) Coumarone series manufactured by Nitto Chemical Co., Ltd. (e.g., Knit Resin Coumarone G-90, Knit Resin Coumarone L-5, Knit Resin Coumarone L-20).

[0049] ((c3) Styrene-based resin) The (c3) styrene-based resin is a polymer containing a styrene-based monomer as a constituent monomer, and examples thereof include a homopolymer obtained by polymerizing one type of styrene-based monomer alone, a copolymer obtained by copolymerizing two or more types of styrene-based monomers, and also a copolymer of a styrene-based monomer and another monomer copolymerizable therewith.

[0050] Examples of styrene-based monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene. These may be used alone or in combination of two or more. Among these, styrene and α-methylstyrene are more preferred.

[0051] The (a3) ​​styrene-based resin is preferably an α-methylstyrene-based resin (such as an α-methylstyrene homopolymer or a copolymer of styrene and α-methylstyrene), and more preferably a styrene-α-methylstyrene resin (a copolymer of styrene and α-methylstyrene).

[0052] Specific examples of the (c3) styrene-based resin include commercially available products such as FTR8000 series (for example, FTR8100) manufactured by Mitsui Chemicals.

[0053] (c4) Rosin resin The damping rubber composition may further contain (c4) a rosin resin, which promotes incorporation of (b) a filler such as silica into (a) the base rubber.

[0054] Examples of the rosin-based resin include rosin ester, hydrogenated rosin ester, disproportionated rosin ester, polymerized rosin ester, etc. These may be used alone or in combination of two or more.

[0055] Specific examples of the rosin-based resin include commercially available products such as the Pine Crystal (registered trademark) series (for example, Pine Crystal KR-85) manufactured by Arakawa Chemical Industries, Ltd.

[0056] ((c5) Terpene-based resin) The (c5) terpene resin is a resin having structural units derived mainly from terpene compounds, and examples thereof include polyterpene resins obtained by (co)polymerizing terpene compounds, terpene-aromatic resins obtained by copolymerizing terpene compounds with aromatic compounds, aromatic-modified polyterpene resins obtained by modifying polyterpene resins with aromatic compounds, hydrogenated products thereof, etc. These (c5) terpene resins may be used alone or in combination of two or more.

[0057] The terpene compound is (C5H8) n The hydrocarbons and their oxygen-containing derivatives are represented by the following composition: monoterpenes (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ), and examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, etc. These terpene compounds may be used alone or in combination of two or more.

[0058] Examples of the aromatic compound include phenolic 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.

[0059] Specific examples of the (c5) terpene resin include commercially available products such as the Sylvatraxx (registered trademark) series (e.g., Sylvatraxx 4150, Sylvatraxx 4125) and the Sylvares (registered trademark) series (e.g., Sylvares TR B115, Sylvares TR M1115) manufactured by Kraton.

[0060] The (c) tackifier preferably contains at least one selected from the group consisting of (c1) dicyclopentadiene-based resins, (c2) coumarone-based resins, and (c3) styrene-based resins. By containing at least one of these (c1) dicyclopentadiene-based resins, (c2) coumarone-based resins, and (c3) styrene-based resins, the damping performance of the resulting damping member can be further improved.

[0061] When the (c) tackifier contains at least one selected from the group consisting of (c1) dicyclopentadiene-based resin, (c2) coumarone-based resin, and (c3) styrene-based resin, the total amount of the (c1) dicyclopentadiene-based resin, (c2) coumarone-based resin, and (c3) styrene-based resin is preferably at least 40 parts by mass, more preferably at least 42 parts by mass, and even more preferably at least 45 parts by mass, and is preferably at most 60 parts by mass, more preferably at most 58 parts by mass, and even more preferably at most 55 parts by mass, per 100 parts by mass of the (a) base rubber. A total amount of 40 parts by mass or more can further improve the damping performance of the resulting damping member, while a total amount of 60 parts by mass or less can improve the dischargeability of the rubber composition after kneading and reduce the temperature dependence of the shear modulus of the resulting damping member.

[0062] The (c) tackifier preferably contains (c4) a rosin resin, which promotes incorporation of (b) filler such as silica into (a) base rubber.

[0063] When the (c) tackifier contains the (c4) rosin-based resin, the content of the (c4) rosin-based resin is preferably at least 5 parts by mass, more preferably at least 7 parts by mass, and preferably at most 20 parts by mass, more preferably at most 15 parts by mass, per 100 parts by mass of the (a) base rubber. If the (c4) rosin-based resin content is 5 parts by mass or more, the incorporation of the (b) filler into the (a) base rubber is promoted and the damping performance of the resulting damping member can be further improved. If the content is 20 parts by mass or less, the rubber composition after kneading will be easily discharged and the temperature dependence of the shear modulus of the resulting damping member will be smaller.

[0064] (vulcanizing agent) The damping rubber composition preferably further contains a vulcanizing agent.

[0065] As the vulcanizing agent, a sulfur-based vulcanizing agent is preferably used. Examples of the sulfur-based vulcanizing agent include powdered sulfur, oil-treated powdered sulfur, precipitated sulfur, colloidal sulfur, and dispersible sulfur. These sulfur-based vulcanizing agents may be used alone or in combination of two or more.

[0066] Specific examples of the vulcanizing agent include commercially available products such as 5% oil-treated powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

[0067] The content of the vulcanizing agent is preferably at least 0.5 parts by mass, more preferably at least 0.8 parts by mass, and even more preferably at least 1.0 part by mass, per 100 parts by mass of the base rubber, and is preferably at most 3.0 parts by mass, more preferably at most 2.5 parts by mass, and even more preferably at most 2.0 parts by mass. If the content of the vulcanizing agent is within the above range, vulcanization is good while suppressing the occurrence of bloom. Note that when oil-treated powdered sulfur, dispersible sulfur, or the like is used as the vulcanizing agent, the content refers to the content of sulfur itself as an active ingredient contained therein.

[0068] (Vulcanization accelerator) The damping rubber composition preferably further contains a vulcanization accelerator.

[0069] Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole (MBT) and 2-benzothiazolyl disulfide (MBTS); dithiocarbamate-based accelerators such as zinc dimethyldithiocarbamate (ZnMDC), zinc diethyldithiocarbamate (ZnEDC), and zinc dibutyldithiocarbamate (ZnBDC); tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), tetrabutylthiuram disulfide (TBTD), and tetrabenzylthiuram disulfide. Examples of suitable vulcanization accelerators include thiuram-based vulcanization accelerators such as TBzTD (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), di-orthotolylguanidine, and orthotolylbiguanidine. These may be used alone or in combination of two or more.

[0070] Specific examples of the vulcanization accelerator include the Accel (registered trademark) series (for example, Accel CZ, Accel TET) manufactured by Kawaguchi Chemical Industry Co., Ltd., and the Noccela (registered trademark) series manufactured by Ouchi Shinko Chemical Co., Ltd.

[0071] The content of the vulcanization accelerator is preferably at least 0.3 parts by mass, more preferably at least 0.4 parts by mass, and even more preferably at least 0.5 parts by mass, per 100 parts by mass of the base rubber, and is preferably at most 2.0 parts by mass, more preferably at most 1.8 parts by mass, and even more preferably at most 1.5 parts by mass. If the content of the vulcanization accelerator is within the above range, the vulcanization acceleration is good and the occurrence of blooming can be suppressed.

[0072] (Other ingredients) 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 vulcanization aids, antioxidants, and softeners, which may be appropriately selected within a range that does not impair the object of the present invention.

[0073] (vulcanization aid) Examples of the vulcanization aid include metal compounds such as zinc oxide, and fatty acids such as stearic acid, oleic acid, cottonseed fatty acid, etc. These vulcanization aids may be used alone or in combination of two or more.

[0074] Specific examples of the vulcanization aid include commercially available products such as Zinc Oxide Type 2 manufactured by Mitsui Mining & Smelting Co., Ltd. and Tsubaki manufactured by NOF Corporation.

[0075] The content of the vulcanization aid is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of the base rubber, and is 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. If the content of the vulcanization aid is within the above range, the vulcanization properties of the rubber composition will be better.

[0076] (anti-aging agent) Examples of the antiaging agent include various antiaging agents such as benzimidazole-based, quinone-based, polyphenol-based, and amine-based. These antiaging agents may be used alone or in combination of two or more. Among these, benzimidazole-based antiaging agents and quinone-based antiaging agents are preferred, and it is more preferred to use a benzimidazole-based antiaging agent and a quinone-based antiaging agent in combination.

[0077] Specific examples of the benzimidazole-based antioxidants include commercially available products such as the Nocrac (registered trademark) series (e.g., Nocrac MB) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Specific examples of the amine-based antioxidants include commercially available products such as the ANTAGE (registered trademark) series (e.g., ANTAGE RD) manufactured by Kawaguchi Chemical Industry Co., Ltd. Specific examples of the quinone-based antioxidants include Antigen FR (aromatic ketone-amine condensate) manufactured by Maruishi Chemicals Co., Ltd.

[0078] The content of the antioxidant is preferably at least 0.5 parts by mass, more preferably at least 1 part by mass, and even more preferably at least 2 parts by mass, per 100 parts by mass of the base rubber, and is preferably at most 8 parts by mass, more preferably at most 6 parts by mass, and even more preferably at most 5 parts by mass. If the content of the antioxidant is within the above range, the rubber composition will have a good anti-aging effect.

[0079] Furthermore, 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, and even more preferably 0.8 or more, and is preferably 5 or less, more preferably 4 or less, and even more preferably 2 or less. When the mass ratio (benzimidazole-based / quinone-based) is within the above range, the antiaging effect of the rubber composition becomes better.

[0080] The damping rubber composition can be prepared, for example, by kneading (a) base rubber, (b) filler, (c) tackifier, vulcanizing agent, vulcanization accelerator, and other components added as needed. The kneading method is not particularly limited, and may be carried out using a known kneading machine such as an internal kneader, kneading roll, Banbury mixer, or kneader.

[0081] <Damping rubber> The present invention includes a damping rubber obtained by curing the damping rubber composition. The damping rubber can be obtained, for example, by pressing the kneaded damping rubber composition at 130°C to 170°C for 20 minutes to 10 hours to simultaneously mold and vulcanize it.

[0082] The damping rubber has excellent damping properties and can therefore be suitably used as a vibration-proof material.

[0083] The damping rubber preferably has an equivalent damping constant heq (23°C) of 0.25 or more, more preferably 0.28 or more, and even more preferably 0.30 or more, measured under conditions of a temperature of 23°C, 100% strain, and a frequency of 0.1 Hz. If the equivalent damping constant heq (23°C) is 0.25 or more, the damping properties of the damping rubber will be good. The upper limit of the equivalent damping constant heq (23°C) is preferably as high as possible, but is usually around 0.50.

[0084] The damping rubber preferably has a ratio (Geq(0°C) / Geq(40°C)) of the equivalent shear modulus Geq(0°C) measured at a temperature of 0°C, 100% strain, and 0.1 Hz to the equivalent shear modulus Geq(40°C) measured at a temperature of 40°C, 100% strain, and 0.1 Hz, of 1.50 or less, more preferably 1.40 or less, and even more preferably 1.35 or less. If the ratio (Geq(0°C) / Geq(40°C)) is 1.50 or less, the low-temperature dependency of the shear modulus of the damping rubber is good. The lower limit of the ratio (Geq(0°C) / Geq(40°C)) is not particularly limited, but 1.00 is preferred.

[0085] <Viscoelastic damper> The present invention includes a viscoelastic damper having a damping member, wherein the damping member is obtained by curing the damping rubber composition. The viscoelastic damper of the present invention has excellent damping properties and can therefore be suitably used as a viscoelastic damper to be installed in a building. [Example]

[0086] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples, and all modifications and embodiments that do not deviate from the spirit of the present invention are included within the scope of the present invention.

[0087] [Evaluation method] <Workability> The components of the rubber composition were kneaded in an internal kneader, and the processability was evaluated by marking "◯" if the process from kneading to discharge went smoothly without any problems, and marking "×" if it did not.

[0088] <Attenuation / temperature dependence> (Preparation of test specimen) Each rubber composition was extruded into a sheet and then punched out to form a rectangular flat plate 1 (8 mm thick x 40 mm long x 40 mm wide) as shown in Figure 1. Next, rectangular flat steel plates 2 (6 mm thick x 44 mm long x 44 mm wide) were placed on both the front and back of this flat plate 1 via a vulcanization adhesive to form a laminate. The laminate was then heated to 140°C while being pressurized in the stacking direction to crosslink the rubber composition forming the flat plate 1 and vulcanize-bond the flat plate 1 to the two steel plates 2, thereby producing specimen 3 as a model of a damping member.

[0089] (Displacement test) Two of the above-mentioned test specimens 3 were prepared as shown in FIG. 2(a), and these two test specimens 3 were each fixed to one central fixture 4 via one of the steel plates 2 with bolts, and one left and one right fixture 5 were fixed to each of the other steel plates 2 of both test specimens 3 with bolts. Next, the central fixture 4 was fixed to an upper fixed arm 6 of a testing machine (not shown) via a joint 7 with bolts, and the two left and right fixtures 5 were fixed to a lower movable platen 8 of the testing machine via joints 9 with bolts. Note that both test specimens 3 were fixed as described above with the two parallel sides of each flat plate 1 aligned parallel to the displacement direction described below. Next, the following operations (I), (II), (III), and (IV) were considered as one cycle, and the plate 1 was repeatedly subjected to strain deformation, i.e., vibration, and a hysteresis loop H (see Figure 3) was obtained, which shows the relationship between the displacement (mm) in the thickness direction and the direction perpendicular to the thickness direction of the plate 1 and the load (N). (I): The movable platen 8 is displaced so as to be pushed upward toward the fixed arm 6 as shown by the white arrow in Figure 2(a), causing the flat plate 1 to be distorted and deformed in the direction perpendicular to the thickness direction as shown in Figure 2(b). (II): From the state shown in FIG. 2(b), the movable platen 8 is displaced so as to be pulled down in the direction opposite to the direction of the fixed arm 6, as shown by the white arrow in FIG. 2(b), to return to the state shown in FIG. 2(c). (III): The movable platen 8 is displaced so as to be pulled down in the direction opposite to the direction of the fixed arm 6, as shown by the white arrow in Figure 2(c), so that the flat plate 1 is distorted and deformed in the direction perpendicular to the thickness direction, as shown in Figure 2(d). (IV): From the state shown in FIG. 2(d), the movable platen 8 is displaced so as to be pushed up toward the fixed arm 6 as shown by the white arrow in FIG. 2(d), and is returned to the state shown in FIG. 2(a).

[0090] The measurements were performed for three cycles of the above operations (I) to (IV), and the value at the third cycle was determined. The maximum displacement in each cycle was set so that the displacement of the two steel plates 2 sandwiching the flat plate 1 in the thickness direction and the perpendicular direction of the flat plate 1 was 100% of the thickness of the flat plate 1. In the displacement test, the deformation frequency was set to 0.1 Hz.

[0091] From the hysteresis loop H in Figure 3 obtained by measurement, the equivalent shear modulus Geq (N / mm 2 ) was sought.

[0092]

number

[0093] In formula (1), Keq (N / mm) is the gradient of a straight line L1, which connects the maximum displacement point and the minimum displacement point of the hysteresis loop H and is shown by a thick solid line in FIG. T (mm) is the thickness of the flat plate 1. A (mm 2 ) is the cross-sectional area of ​​the plate 1.

[0094] Furthermore, the equivalent damping constant heq was calculated from the hysteresis loop H in FIG. 3 using the following formula (2).

[0095]

number

[0096] In equation (2), ΔW is the amount of absorbed energy represented by the total surface area of ​​the hysteresis loop H, which is shown by the hatched area in FIG. W is the elastic strain energy, which is expressed as the surface area of ​​the triangle region enclosed by the cross-hatched line in Figure 3, the horizontal axis of the graph (load is 0 N), and the perpendicular line L2 drawn from the intersection of the line L1 and the hysteresis loop H to the horizontal axis of the graph.

[0097] (Damping evaluation) The equivalent damping constant heq (23°C) at which the displacement measured in an environment at 23°C is 100% was used as an index of damping performance. The larger the equivalent damping constant heq (23°C), the better the damping performance. An equivalent damping constant heq (23°C) of 0.30 or more was marked with "◎", one between 0.25 and 0.30 was marked with "○", and one less than 0.25 was marked with "×".

[0098] (Temperature dependency evaluation) The ratio of the equivalent shear modulus Geq(40°C) measured in an environment at a temperature of 40°C to the equivalent shear modulus Geq(0°C) at which the displacement is 100% measured in an environment at a temperature of 0°C, i.e., Geq(0°C) / Geq(40°C), was used as an index of temperature dependency. The closer this ratio is to 1, the smaller the temperature dependency is indicated. A ratio (Geq(0°C) / Geq(40°C)) of 1.5 or less was evaluated as "Good", and a ratio of more than 1.5 was evaluated as "Poor".

[0099] <Overall rating> If the evaluation results for the temperature dependence of processability, damping property, and shear modulus were all "◎" or "◯," the overall evaluation was rated as "pass," and if any one of the evaluation results for the temperature dependence of processability, damping property, and shear modulus was "×," the overall evaluation was rated as "fail."

[0100] The components shown in Table 1 were kneaded together using an internal kneader to prepare a rubber composition.

[0101] [Table 1]

[0102] The components in Table 1 are as follows: SBR1: Asahi Kasei Corporation, "HS265" (styrene butadiene rubber) (glass transition temperature: -60°C) SBR2: BST ENEOS Elastomer, "SL553R" (styrene butadiene rubber) (glass transition temperature: -64°C) SBR3: Zeon Corporation's "SBR1502" (styrene butadiene rubber) (glass transition temperature: -52°C) NR: "TSR20" (natural rubber) (glass transition temperature: -74°C) Silica: Tosoh Silica Corporation, "Nipsil KQ" (primary particle diameter: 14 nm, BET specific surface area: 220 m 2 / g) Carbon black: Tokai Carbon Co., Ltd. (product name: SEAT 3, arithmetic mean particle size: 28 nm, nitrogen adsorption specific surface area: 79 m 2 / g) Phenyltriethoxysilane: Shin-Etsu Silicone Co., Ltd., "KBE-103" Dicyclopentadiene resin: Maruzen Petrochemical Co., Ltd., "Marukarets (registered trademark) M890" Coumarone resin: "Cumarone G90" (coumarone-indene resin) manufactured by Nitto Chemical Co., Ltd. Styrene-based resin: Mitsui Chemicals, Inc.'s "FTR8100" (alpha-methylstyrene resin) Rosin resin: Arakawa Chemical Industries, Ltd., "Pine Crystal (registered trademark) KR-85" TOP: "TOP" (tris(2-ethylhexyl)phosphate) manufactured by Daihachi Chemical Co., Ltd. Sulfur: Tsurumi Chemical Industry Co., Ltd., 5% oil-treated powder sulfur Accel (registered trademark) CZ: manufactured by Kawaguchi Chemical Industry Co., Ltd., sulfenamide-based vulcanization accelerator Accel (registered trademark) TET: manufactured by Kawaguchi Chemical Industry Co., Ltd., a thiuram-based vulcanization accelerator Zinc oxide: Mitsui Mining & Smelting Co., Ltd., zinc oxide type 2 Stearic acid: NOF Corporation, Tsubaki Nocrac (registered trademark) MB: manufactured by Ouchi Shinko Chemical Industry Co., Ltd., a benzimidazole-based antioxidant ANTAGE® RD: Kawaguchi Chemical Industry Co., Ltd., amine-based antioxidant

[0103] As shown in Table 1, rubber compositions Nos. 1 to 5 contain (a) a styrene-butadiene rubber having a glass transition temperature of −55° C. or lower as a base rubber, (b) a filler, and (c) a predetermined amount of a tackifier. These rubber compositions Nos. 1 to 5 have good processability, and the resulting damping members have excellent damping properties and little temperature dependency of the shear modulus.

[0104] Rubber compositions Nos. 6 and 7 are (a) cases in which the base rubber does not contain a styrene-butadiene rubber having a glass transition temperature of −55° C. or lower. The damping members formed from these rubber compositions Nos. 6 and 7 had excellent damping properties, but the shear modulus had a high temperature dependency.

[0105] Rubber composition No. 8 is a case where (b) the filler content is too low, and the damping member formed from this rubber composition No. 8 had poor damping properties. Rubber composition No. 9 is a case where the content of (b) the filler was too high, and this rubber composition No. 9 had poor processability and could not be kneaded.

[0106] Rubber composition No. 10 is a case where the content of (c) the tackifier is too small, and the damping member formed from this rubber composition No. 10 had poor damping properties. Rubber composition No. 11 is a case where the content of (c) the tackifier was too high, and this rubber composition No. 11 had high tackiness and poor processability.

[0107] The present invention (1) is a damping rubber composition comprising (a) a base rubber, (b) a filler, and (c) a tackifier, wherein the (a) base rubber contains styrene-butadiene rubber, and the glass transition temperature of the styrene-butadiene rubber is −55° C. or lower, the amount of the (b) filler is 120 parts by mass or more and 170 parts by mass or less per 100 parts by mass of the (a) base rubber, and the amount of the (c) tackifier is 40 parts by mass or more and 80 parts by mass or less per 100 parts by mass of the (a) base rubber.

[0108] The present invention (2) is the damping rubber composition according to the present invention (1), wherein the (c) tackifier contains at least one selected from the group consisting of (c1) dicyclopentadiene-based resins, (c2) coumarone-based resins, and (c3) styrene-based resins.

[0109] The present invention (3) is the damping rubber composition according to the present invention (2), wherein the total content of the (c1) dicyclopentadiene-based resin, the (c2) coumarone-based resin, and the (c3) styrene-based resin is 40 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the (a) base rubber.

[0110] The present invention (4) is the damping rubber composition according to any one of the present inventions (1) to (3), wherein the tackifier (c) further contains a rosin resin (c4).

[0111] The present invention (5) is a viscoelastic damper provided with a damping member, characterized in that the damping member is obtained by curing the damping rubber composition according to any one of the present inventions (1) to (4). [Explanation of symbols]

[0112] 1: Flat plate, 2: Steel plate, 3: Test specimen, 4: Central fixture, 5: Left and right fixtures, 6: Fixed arm, 7: Joint, 8: Movable platen, 9: Joint, H: Hysteresis loop, L1: Line, L2: Perpendicular line, W: Elastic strain energy, ΔW: Amount of absorbed energy, Keq: Slope of line L1

Claims

1. (a) a base rubber, (b) a filler, and (c) a tackifier; the (a) base rubber contains a styrene-butadiene rubber, and the glass transition temperature of the styrene-butadiene rubber is −55° C. or lower; the content of the (b) filler is 120 parts by weight or more and 170 parts by weight or less per 100 parts by weight of the (a) base rubber, A damping rubber composition, characterized in that the content of the tackifier (c) is 40 parts by mass or more and 80 parts by mass or less per 100 parts by mass of the base rubber (a).

2. 2. The damping rubber composition according to claim 1, wherein the tackifier (c) contains at least one selected from the group consisting of a dicyclopentadiene-based resin (c1), a coumarone-based resin (c2), and a styrene-based resin (c3).

3. 3. The damping rubber composition according to claim 2, wherein a total content of the (c1) dicyclopentadiene-based resin, the (c2) coumarone-based resin, and the (c3) styrene-based resin is 40 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the (a) base rubber.

4. The damping rubber composition according to claim 2, wherein the tackifier (c) further contains a rosin resin (c4).

5. A viscoelastic damper having a damping member, A viscoelastic damper, wherein the damping member is obtained by curing the damping rubber composition according to any one of claims 1 to 4.

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