Damping rubber composition and viscoelastic damper

Abstract

To provide a damping rubber composition that offers superior damping performance and prevents load reduction in the region beyond the maximum load strain.SOLUTION: A damping rubber composition contains a base rubber having polymerizable double bonds, silica, and 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane, where the content of 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane is 0.5 pt.mass or more and 4.0 pts.mass or less relative to 100 pts.mass of the base rubber having polymerizable double bonds.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Damping members are used in a wide range of fields, including buildings and bridges, industrial machinery, aircraft, automobiles, railroad cars, computers and their peripheral devices, household electrical appliances, and even automobile tires. Damping members can provide seismic isolation, vibration control, vibration damping, vibration isolation, and the like by mitigating and / or absorbing the transmission of vibration energy.

[0003] For example, Patent Document 1 discloses a method for producing a high damping composition, which includes a step of kneading two types of crosslinkable rubber, i.e., polyisoprene rubber and polybutadiene rubber, and 100 to 150 parts by mass of silica, 1 to 10 parts by mass of an alkyl-type silylating agent, 15 to 30 parts by mass of a phenyl-type silylating agent, and 1 to 10 parts by mass of a silane coupling agent, per 100 parts by mass of the total amount of the two types of crosslinkable rubber, at a temperature of 145°C or higher and 175°C or lower.

[0004] Patent Document 2 discloses an anti-vibration rubber composition comprising natural rubber (NR) and ethylene-propylene-diene rubber (EPDM) as main components, the mixture ratio of the natural rubber (NR) / ethylene-propylene-diene rubber (EPDM) being 45 / 55 to 70 / 30 by mass, containing a peroxide as a vulcanizing agent and zinc acrylate or zinc methacrylate as a co-crosslinking agent, and further containing 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)-hexane.

[0005] Patent Document 3 discloses a rubber composition for coating a steel cord, which contains a diene rubber, sulfur, an imidazole antioxidant, and 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane.

[0006] Patent Document 4 discloses a rubber composition that contains a rubber component containing at least one type of diene rubber, a filler, a vulcanizing agent, a compound represented by formula (1) (e.g., 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane), a compound represented by formula (2) (e.g., N-phenyl-N-(trichloromethylthio)benzenesulfonamide), and a vulcanization accelerator other than the compound represented by formula (1), in which the total amount of the vulcanization accelerator and the compound represented by formula (1) is 1.3 to 2.0 parts by mass relative to 100 parts by mass of the rubber component. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2018-123205 A [Patent Document 2] JP 2013-18884 A [Patent Document 3] Patent Publication No. 2021-80410 [Patent Document 4] International Publication No. WO2019 / 107428 Summary of the Invention [Problem to be solved by the invention]

[0008] In vibration dampers, high-damping rubber with high rigidity is sometimes required to increase strength. In high-damping rubber compounds made from base rubbers with double bonds such as natural rubber, it is common to increase the amount of vulcanizing agent or add fillers such as carbon or silica to impart rigidity. Natural rubber and other rubbers have high elongation crystallinity, which causes a hardening phenomenon in which stress increases rapidly during large deformation. This phenomenon also poses the problem of having to increase the strength of surrounding components such as pillars.

[0009] Furthermore, when polymers having polymerizable double bonds are vulcanized with sulfur, the crosslinked chains trigger the rubber to become fully stretched during large deformation, which can easily cause hardening. If the rubber is then subjected to large deformation until it breaks, the polymer chains and crosslinked chains break, causing a sudden drop in load.

[0010] The present invention has been made in consideration of the above circumstances, and has an object to provide a damping rubber composition that is excellent in damping performance and suppresses load reduction in a region exceeding the maximum load strain. Another object of the present invention is to provide a rubber with excellent damping performance and a viscoelastic damper using the same. [Means for solving the problem]

[0011] The damping rubber composition of the present invention, which has been able to solve the above problems, contains a base rubber having a polymerizable double bond, silica, and 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane, and is characterized in that the blending amount of 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane is 0.5 parts by mass or more and 4.0 parts by mass or less per 100 parts by mass of the base rubber having a polymerizable double bond. Effect of the Invention

[0012] According to the present invention, a damping rubber composition having excellent damping performance and suppressing load reduction in a region exceeding the maximum load strain can be obtained. According to the present invention, a damping rubber and a viscoelastic damper having excellent damping performance can be obtained. [Brief description of the drawings]

[0013] [Figure 1] 1 is an exploded perspective view showing a test specimen as a model of a damping member prepared in order to evaluate the damping characteristics of the damping member using the damping rubber composition of the present invention; [Diagram 2] FIG. 2 is a diagram for explaining an outline of a testing machine for determining the relationship between the amount of displacement and the load by displacing the test specimen. [Diagram 3]4 is a graph showing an example of a hysteresis loop showing the relationship between the displacement amount and the load, which is obtained by displacing a test specimen using the testing machine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <Damping Rubber Composition> The damping rubber composition of the present invention is characterized in that it contains a base rubber having a polymerizable double bond, silica, and 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane, and the blending amount of 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane is 0.5 parts by mass or more and 4.0 parts by mass or less per 100 parts by mass of the base rubber having a polymerizable double bond.

[0015] The rubber composition of the present invention contains a base rubber having a polymerizable double bond (sometimes simply referred to as "base rubber" in the present invention). The base rubber is not particularly limited as long as it is a rubber having a polymerizable double bond. The polymerizable double bond is a double bond that is cleaved and polymerized by heating, exposure to light and / or radiation, and is preferably, for example, a carbon-carbon double bond derived from ethylene. For example, a carbon-carbon double bond in a benzene ring is stable and does not correspond to the polymerizable double bond of the present invention.

[0016] Examples of the rubber having a polymerizable double bond include natural rubber and synthetic rubber.

[0017] Examples of the rubber having a polymerizable double bond include diene rubbers such as polybutadiene rubber (BR), polyisoprene rubber (IR), styrene butadiene rubber (SBR), chloroprene rubber (CR), butyl rubber (IIR), and acrylonitrile butadiene rubber (NBR), and non-diene rubbers such as ethylene-propylene-diene rubber (EPDM). These may be used alone or in combination of two or more.

[0018] The base rubber having a polymerizable double bond preferably contains a polyisoprene rubber.

[0019] The polyisoprene rubber is not particularly limited as long as it is a rubber having a structural unit derived from isoprene. Examples of the polyisoprene rubber include natural rubber (NR) and synthetic rubber. Natural rubber is derived from a rubber-containing plant and contains pure cis-1,4-polyisoprene. Synthetic polyisoprene rubber is synthesized by polymerizing a monomer containing isoprene (preferably a monomer mainly composed of isoprene). The natural rubber and synthetic polyisoprene rubber may be modified rubber. These polyisoprene rubbers may be used alone or in combination.

[0020] Examples of the natural rubber include various grades of natural rubber such as SMR (Standard Malaysian Rubber)-CV60, and various deproteinized natural rubbers.

[0021] Examples of the synthetic polyisoprene rubber include polyisoprene rubber (IR), butadiene-isoprene copolymer rubber (BIR), styrene-isoprene copolymer rubber (SIR), styrene-butadiene-isoprene copolymer rubber (SBIR), and modified rubbers thereof.

[0022] The polyisoprene rubber (IR) preferably contains 90% by mass or more of isoprene, more preferably 94% by mass or more, and even more preferably 98% by mass or more of isoprene in all monomer components constituting the polyisoprene rubber. Also, the polyisoprene rubber (IR) preferably consists essentially of 100% by mass of isoprene.

[0023] Among the synthetic polyisoprene rubbers, polyisoprene rubber (IR) is preferred, and high cis-1,4-polyisoprene rubber containing 90% by mass or more of cis-1,4-bonds is more preferred.

[0024] Specific examples of the polyisoprene rubber include commercially available products such as Nipol (registered trademark) IR series (eg, IR2200) manufactured by Zeon Corporation.

[0025] The content of the polyisoprene-based rubber in the base rubber having a polymerizable double bond is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. In a preferred embodiment, the base rubber having a polymerizable double bond is made of a polyisoprene-based rubber. When the content of the polyisoprene-based rubber is within the above range, the effects of the present invention can be obtained satisfactorily.

[0026] The damping rubber composition of the present invention may contain a rubber having no polymerizable double bonds in addition to the base rubber having a polymerizable double bond, as long as the effect of the present invention is not impaired.

[0027] Examples of the rubber having no polymerizable double bond include non-diene rubbers such as ethylene propylene rubber (EPM), urethane rubber, silicone rubber, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, fluororubber, and chlorosulfonated polyethylene rubber.

[0028] The amount of the rubber having no polymerizable double bonds is preferably no more than 40 parts by mass, more preferably no more than 20 parts by mass, and even more preferably no more than 10 parts by mass, per 100 parts by mass of the base rubber having a polymerizable double bond.

[0029] The base rubber used in the present invention is preferably a solid at 25° C., and the polyisoprene-based rubber used in the present invention is more preferably a solid at 25° C. The base rubber does not include liquid rubber used as a softener, which will be described later.

[0030] (silica) The silica contained in the damping rubber composition of the present invention imparts damping properties to the base rubber. Examples of the silica include synthetic silica having a porous structure, which is mainly produced by chemically reacting silica sand as a raw material.

[0031] The silica may be either wet-process silica or dry-process silica, which are classified according to the manufacturing method. In order to further improve the damping performance, the BET specific surface area of ​​the silica is preferably 100 m 2 / g or more, more preferably 120m 2 / g or more, more preferably 150m 2 In order to further improve processability and fracture resistance, the BET specific surface area of ​​the silica is preferably 400 m 2 / g or less, more preferably 300m 2 / g or less, more preferably 250m 2 / g or less. The BET specific surface area is a value measured by a gas phase adsorption method using nitrogen gas as an adsorption gas. These silicas may be used alone or in combination of two or more kinds.

[0032] Specific examples of the silica include commercially available products such as the Nipsil (registered trademark) series manufactured by Tosoh Silica Corporation (eg, Nipsil VN3, Nipsil AQ, Nipsil KQ) and the Ultrasil (registered trademark) series manufactured by Evonik Corporation (eg, Ultrasil VN3).

[0033] The content of the silica is preferably 100 parts by mass or more, more preferably 120 parts by mass or more, and even more preferably 130 parts by mass or more, and is preferably 180 parts by mass or less, more preferably 160 parts by mass or less, and even more preferably 150 parts by mass or less, based on 100 parts by mass of the base rubber. By keeping the content of silica within the above range, the damping performance and processability are improved.

[0034] The damping rubber composition of the present invention contains 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane.

[0035] According to the present invention, by blending an appropriate amount of the 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane, the number of S-Cx-S bonds, which are of a length equivalent to a polysulfide bond and are difficult to break even when heated too much, is increased. This makes the entanglement of molecular chains more complex, and the timing of molecular chain breakage is not uniform. As a result, even in the region exceeding the maximum load strain, the proportion of molecular chains that are not broken increases, and it is believed that the load reduction is suppressed.

[0036] 1,6-Bis(N,N-dibenzylthiocarbamoyldithio)hexane has the following structure:

[0037] [ka]

[0038] Specific examples of the 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane include commercially available products such as Vulcuren (registered trademark) manufactured by LANXESS.

[0039] The content of the 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more, and is preferably 4.0 parts by mass or less, more preferably 3.5 parts by mass or less, and even more preferably 3.0 parts by mass or less, based on 100 parts by mass of the base rubber. If the content of 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane is 0.5 parts by mass or more, load reduction is suppressed even in a region exceeding the maximum load strain. If the content of 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane is 4.0 parts by mass or less, the damping performance is good and blooming can be suppressed.

[0040] (Vulcanizing agent) The damping rubber composition of the present invention may or may not contain a vulcanizing agent.

[0041] 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, and dispersible sulfur. These sulfur-based vulcanizing agents may be used alone or in combination of two or more.

[0042] Specific examples of the vulcanizing agent include commercially available products such as 5% oil-treated powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

[0043] The content of the vulcanizing agent, per 100 parts by mass of the base rubber, is preferably 0 part by mass or more, more preferably 0.1 part by mass or more, and even more preferably 0.5 parts by mass or more, and is preferably 2.5 parts by mass or less, more preferably 2.2 parts by mass or less, and even more preferably 2.0 parts by mass or less.

[0044] If the content of the vulcanizing agent is 2.5 parts by mass or less, reversion is prevented, the damping performance is good, and the occurrence of bloom can be suppressed. When oil-treated powdered sulfur or dispersible sulfur is used as the vulcanizing agent, the content is the content of sulfur itself as an active ingredient contained therein.

[0045] (Vulcanization accelerator) The damping rubber composition of the present invention preferably further contains a vulcanization accelerator.

[0046] Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide; dithiocarbamate-based accelerators such as zinc dimethyldithiocarbamate; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. As commercially available products, products from Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., etc. can be used. These may be used alone or in combination of two or more kinds.

[0047] Specific examples of the vulcanization accelerator include the Noccela (registered trademark) series (for example, Noccela NS) manufactured by Ouchi Shinko Chemical Co., Ltd.

[0048] The content of the vulcanization accelerator is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.7 parts by mass or more, and is preferably 2.5 parts by mass or less, more preferably 2.2 parts by mass or less, and even more preferably 2.0 parts by mass or less, based on 100 parts by mass of the rubber component.

[0049] When the content of the vulcanization accelerator is 0.3 parts by mass or more, the fracture durability is good. When the content of the vulcanization accelerator is 2.5 parts by mass or less, reversion is prevented, the damping performance is good, and the occurrence of blooming can be suppressed.

[0050] (tackifier) The damping rubber composition of the present invention preferably further contains a tackifier.

[0051] Examples of the tackifier include petroleum-based resins, rosin and / or rosin derivatives, coumarone-based resins, etc. These tackifiers may be used alone or in combination of two or more kinds.

[0052] The petroleum resins include aliphatic petroleum resins obtained by polymerizing aliphatic olefins and / or aliphatic diolefins; aromatic petroleum resins obtained by polymerizing aromatic compounds having olefinic unsaturated bonds; aliphatic-aromatic copolymer petroleum resins obtained by copolymerizing aliphatic olefins and / or aliphatic diolefins with aromatic compounds having olefinic unsaturated bonds; dicyclopentadiene petroleum resins obtained by polymerizing cyclopentadiene or dicyclopentadiene; dicyclopentadiene-aromatic copolymer petroleum resins obtained by copolymerizing cyclopentadiene or dicyclopentadiene with aromatic compounds having olefinic unsaturated bonds, etc. The aromatic petroleum resins also include styrene resins obtained by polymerizing styrene compounds (styrene, α-methylstyrene, β-methylstyrene).

[0053] The petroleum resin may also be a hydrogenated petroleum resin obtained by adding hydrogen atoms to a polymer obtained by polymerizing the petroleum fraction or a chemically synthesized unsaturated compound. By adding hydrogen atoms, the double bonds in the molecule are hydrogenated. The hydrogenated product may be either a fully hydrogenated petroleum resin in which all double bonds in the molecule are hydrogenated, or a partially hydrogenated petroleum resin in which some of the double bonds in the molecule are hydrogenated.

[0054] Examples of hydrogenated petroleum resins include hydrogenated aliphatic petroleum resins obtained by hydrogenating aliphatic petroleum resins; hydrogenated aromatic petroleum resins obtained by hydrogenating aromatic petroleum resins; hydrogenated aliphatic-aromatic copolymer petroleum resins obtained by hydrogenating aliphatic-aromatic copolymer petroleum resins; hydrogenated dicyclopentadiene petroleum resins obtained by hydrogenating dicyclopentadiene petroleum resins; and hydrogenated dicyclopentadiene-aromatic copolymer petroleum resins obtained by hydrogenating dicyclopentadiene-aromatic copolymer petroleum resins.

[0055] Specific examples of the petroleum-based resin include commercially available products such as the MARKAREZ (registered trademark) M series (e.g., MARKAREZ M-890A) manufactured by Maruzen Petrochemical Co., Ltd. and the QUINTON (registered trademark) series (e.g., QUINTON 1325) manufactured by Zeon Co., Ltd. Specific examples of the rosin-based resin include commercially available products such as the HARITACK (registered trademark) series and the HARIESTAR (registered trademark) series (e.g., HARITACK HD21) manufactured by Harima Chemical Co., Ltd.

[0056] Rosin is a residue remaining after collecting balsams such as pine resin, which is the sap of plants of the Pinaceae family, and distilling turpentine essential oil, and is a natural resin mainly composed of rosin acid (abietic acid, palustric acid, isopimaric acid, etc.). Examples of rosin include raw rosins such as gum rosin, wood rosin, and tall oil rosin, as well as refined products thereof. These rosins may be used alone or in combination of two or more.

[0057] The rosin derivative is not particularly limited as long as it is a derivative of the rosin, and examples thereof include those obtained by subjecting the rosin to treatments such as hydrogenation, disproportionation, polymerization, esterification, modification (e.g., acid modification), and other chemical modifications. These treatments may be performed by one type or by two or more types. Examples of the rosin derivative include rosin ester, disproportionated rosin, disproportionated rosin ester, polymerized rosin, polymerized rosin ester, hydrogenated rosin, hydrogenated rosin ester, modified rosin, and modified rosin ester. These rosin derivatives may be used alone or in combination of two or more types.

[0058] The rosin and / or rosin derivative may be a commercially available product, such as Hariestar P (pentaerythritol rosin ester, acid value: 6 to 12 mgKOH / g), Hariestar DS-70L (rosin ester, acid value: 8 mgKOH / g or less), Haritac R-80 (rosin ester, acid value: 20 mgKOH / g or less), Haritac FK100 (disproportionated rosin ester, acid value: 5 mgKOH / g or less), Haritac FK125 (disproportionated rosin ester, acid value: 14 to 20 mgKOH / g), and Haritac S, all of which are manufactured by Harima Chemicals. Rosin esters such as E10 (hydrogenated rosin ester, acid value: 2-10 mgKOH / g), Haritac F85 (hydrogenated rosin ester, acid value: 4-12 mgKOH / g), Haritac PH (hydrogenated rosin ester, acid value: 7-16 mgKOH / g), Haritac AQ-90A (rosin modified special synthetic resin, acid value: 100-110 mgKOH / g); Haritac F-75 (special modified rosin, acid value: 145 mgKOH / g or more), Haritac FG-90 (special modified rosin , acid value: 140-160mgKOH / g), Halimac T-80 (maleic rosin, acid value: 170-200mgKOH / g), Halimac R-100 (maleic rosin ester, acid value: 25mgKOH / g or less), Halimac M-453 (maleic rosin ester, acid value: 25mgKOH / g or less), Halitac 4740 (maleic rosin ester, acid value: 25-35mgKOH / g), Hariestar MSR-4 (maleic rosin ester, acid value: modified rosins and modified rosin esters such as Haritac 28JA (maleic rosin ester, acid value: 120-150 mgKOH / g) and Haritac 28JA (maleic rosin ester, acid value: 39 mgKOH / g or less); and polymerized rosin esters such as Haritac PCJ (polymerized rosin ester, acid value: 16 mgKOH / g or less), Hariestar DS-130 (polymerized rosin ester, acid value: 20 mgKOH / g or less), and Hariestar KT-3 (polymerized rosin ester, acid value: 17 mgKOH / g or less).

[0059] The coumarone resin is a resin having a structural unit derived mainly from coumarone, and examples thereof include coumarone resin, coumarone-indene resin, copolymer resin mainly composed of coumarone, indene and styrene, etc. These coumarone resins may be used alone or in combination of two or more kinds.

[0060] Specific examples of the coumarone resin include commercially available products such as the Knit Resin (registered trademark) Coumarone series manufactured by Nippon Paint Chemical Co., Ltd. (for example, Knit Resin Coumarone G-90, Knit Resin Coumarone L-5, and Knit Resin Coumarone L-20).

[0061] The content of the tackifier is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, and even more preferably 10 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less, based on 100 parts by mass of the rubber component.

[0062] This is because when the content of the tackifier is within the above range, the processability is improved.

[0063] (Other Ingredients) In addition to the above-mentioned components, the damping rubber composition of the present invention may further contain various additives that can be used in damping rubber compositions, such as fillers, vulcanization aids, softeners, antioxidants, silane coupling agents, etc., which may be appropriately selected within the scope not impairing the object of the present invention.

[0064] [Filler] Examples of the filler include carbon black. The type of carbon black is not particularly limited. Examples of the carbon black include furnace carbon black 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 black such as FT (Fine Thermal Black) and MT (Medium Thermal Black); channel carbon black 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.

[0065] Specific examples of the carbon black include commercially available products such as the Seast series (eg, Seast 3) manufactured by Tokai Carbon Co., Ltd.

[0066] The amount of the filler per 100 parts by mass of the base rubber 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, 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, because the processability is improved if the filler amount is within the above range.

[0067] [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 kinds.

[0068] 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.

[0069] 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, 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, per 100 parts by mass of the base rubber. If the content of the vulcanization aid is within the above range, the vulcanization rate can be controlled and processability is improved.

[0070] 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, and preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less. When the mass ratio of the metal compound to the fatty acid is within the above range, the effects of the present invention can be obtained more satisfactorily.

[0071] [Softener] Examples of the softener include various liquid rubbers that are liquid at room temperature. These softeners may be used alone or in combination of two or more kinds.

[0072] Examples of the liquid rubber include liquid polybutadiene rubber, liquid polyisoprene rubber, and liquid polystyrene butadiene rubber. Specific examples thereof include commercially available products such as Kuraray Co., Ltd.'s Kurapren (registered trademark) LIR series, LBR series, and L-SBR series (e.g., LIR-30 and LIR-50). The liquid rubbers can be used alone or in combination of two or more.

[0073] The content of the softener, relative to 100 parts by mass of the base rubber, is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, and even more preferably 10 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less, because the processability is improved if the content of the softener is within the above range.

[0074] [Silane coupling agents] The damping rubber composition of the present invention may contain a silane coupling agent, which improves the dispersibility of silica in the base rubber.

[0075] Examples of the silane coupling agent include sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, NXT-Z100, NXT-Z45, and NXT manufactured by Momentive; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; Examples of the silane coupling agents include amino-based silane coupling agents such as methoxysilane and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane; etc. These silane coupling agents may be used alone or in combination of two or more.

[0076] When the silane coupling agent is contained, the content of the silane coupling agent is preferably 10 parts by mass or more, more preferably 12 parts by mass or more, and even more preferably 15 parts by mass or more, based on 100 parts by mass of silica. The content of the silane coupling agent is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, based on 100 parts by mass of silica.

[0077] [Anti-aging agent] Examples of the antiaging agent include one or more of various antiaging agents such as benzimidazole-based, quinone-based, polyphenol-based, amine-based, etc. In particular, it is preferable to use a benzimidazole-based antiaging agent and a quinone-based antiaging agent in combination.

[0078] Among these, an example of the benzimidazole-based antioxidant is 2-mercaptobenzimidazole, etc. The compounding ratio of the benzimidazole-based antioxidant is preferably at least 0.5 parts by mass and at most 5 parts by mass per 100 parts by mass of the base rubber.

[0079] An example of a quinone-based anti-aging agent is Antigen FR (aromatic ketone-amine condensate) manufactured by Maruishi Chemical Co., Ltd.

[0080] The blending ratio of the quinone-based antioxidant is preferably at least 0.5 parts by weight and at most 5 parts by weight per 100 parts by weight of the base rubber.

[0081] The damping rubber composition of the present invention can be prepared, for example, by kneading the base rubber, silica, 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane, and vulcanizing agents, vulcanization accelerators, tackifiers, and other components that are added as necessary. The kneading method is not particularly limited, and may be performed using a known kneading machine such as an internal kneader, a kneading roll, a Banbury mixer, or a kneader.

[0082] The damping rubber composition of the present invention can be molded in a mold after kneading. The molding temperature is preferably 120° C. or higher, more preferably 130° C. or higher, even more preferably 140° C. or higher, and preferably 170° C. or lower. The molding time is preferably 20 to 120 minutes.

[0083] <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 used as a seismic isolation material, a vibration-damping material, a vibration-damping material, or a vibration-proof material because it reduces and / or absorbs the transmission of vibration energy.

[0084] <Viscoelastic damper> In particular, the damping rubber obtained by curing the damping rubber composition of the present invention can be suitably used as a viscoelastic damper to be incorporated into the structure of a building. The viscoelastic damper of the present invention absorbs vibration energy and reduces shaking by the deformation of the damping rubber, which is a viscoelastic body. EXAMPLES

[0085] 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.

[0086] [Evaluation method]

[0087] <Attenuation characteristic test> (Preparation of test specimen) Each damping rubber composition was extruded into a sheet and then punched out to form a flat plate 1 (5 mm thick x 25 mm long x 25 mm wide) with a rectangular planar shape as shown in Fig. 1. Next, rectangular flat steel plates 2 measuring 6 mm thick x 44 mm long x 44 mm wide were laminated on both the front and back sides of the flat plate 1 via a vulcanizing adhesive to form a laminate. The laminate was then heated to 150°C while being pressurized in the lamination direction to crosslink the damping rubber composition forming the flat plate 1, and the flat plate 1 was vulcanized and bonded to two steel plates 2 to produce a test specimen 3 for evaluating damping characteristics as a model of a damping member.

[0088] (Displacement test) Two test specimens 3 were prepared as shown in Fig. 2(a), and the two test specimens 3 were fixed to one central fixture 4 via one of the steel plates 2, and one left and right fixture 5 was fixed to the other steel plate 2 of each of the 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, and the two left and right fixtures 5 were fixed to a lower movable platen 8 of the testing machine via a joint 9. Both test specimens 3 were fixed as described above with the two parallel sides of the flat plate 1 aligned parallel to the displacement direction described below.

[0089] (Simple Displacement Test) Next, the following operations (I) and (II) were considered as one cycle, and the flat plate 1 was repeatedly distorted, i.e., vibrated, to obtain a hysteresis loop H (see Figure 3) showing the relationship between the displacement (mm) in the direction perpendicular to the thickness direction (stacking direction) of the flat 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 a direction perpendicular to the thickness direction (stacking direction) as shown in Figure 2(b). (II): From the above state, the movable platen 8 is then displaced so as to be pulled down in the direction opposite to the direction of the fixed arm 6, as indicated by the outlined arrow in FIG. 2(b), to return it to the state shown in FIG. 2(a).

[0090] The measurements were performed in an environment at a temperature of 20° C., and the value at the sixth cycle was obtained by performing six cycles of the above operations (I) and (II). The maximum displacement in each cycle was set so that the amount of displacement of the two steel plates 2 sandwiching the flat plate 1 in the direction perpendicular to the thickness direction (stacking direction) of the flat plate 1 was 100% of the thickness of the flat plate 1.

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

number

[0092] In addition, the equivalent damping constant heq was calculated from the hysteresis loop H in FIG.

number

[0093] The equivalent shear modulus Geq of each rubber composition was calculated relative to the equivalent shear modulus Geq of the damping rubber composition No. 1, which was set at 100. The damping performance was evaluated based on the relative values ​​according to the following criteria. A larger relative value indicates better damping performance. 〇: 100 or more, △: Less than 100, 80 or more ×: Less than 80

[0094] In addition, the equivalent damping constant heq of each rubber composition was calculated relative to the equivalent damping constant heq of the damping rubber composition No. 1, which was set to 100. The damping performance was evaluated based on the relative values ​​according to the following evaluation criteria. A larger relative value indicates better damping performance. 〇: 90 or more △: Less than 90, 80 or more, ×: Less than 80

[0095] (Limit deformation test) The movable platen 8 is displaced so as to be pushed upward toward the fixed arm 6 as shown by the white arrow in Fig. 2(a), and the flat plate 1 is deformed in a direction perpendicular to the thickness direction as shown in Fig. 2(b). An SN load curve was obtained, which shows the relationship between the displacement (mm) of the flat plate 1 in the direction perpendicular to the thickness direction (lamination direction) and the load (N) when the flat plate 1 is deformed until the displacement (mm) reaches 50 mm. In the obtained SN load curve, the displacement at the maximum load was defined as the "displacement at maximum load". The load when the flat plate 1 is further deformed from the "displacement at maximum load" to 100% of the thickness of the flat plate 1 was defined as the "load after maximum load", and the load reduction rate was calculated by the following formula (3).

[0096] Load reduction rate (%) = Maximum load after load / Maximum load × 100 The load reduction rate was evaluated according to the following criteria. The larger the value, the better the result. 〇: 90 or more, △: Less than 90, 80 or more, ×: Less than 80

[0097] <Overall Judgment> If the evaluation results of the damping performance, simple displacement test, and ultimate deformation test are all "O" or there is only one "△", the overall judgment is "Pass (O)". If the evaluation results of the damping performance, simple displacement test, and ultimate deformation test are two or more "△", the overall judgment is "△". If any one of the evaluation results of the damping performance, simple displacement test, and ultimate deformation test is "X", the overall judgment is "Fail (X)".

[0098] The components shown in Table 1 were mixed together in an internal mixer to prepare a rubber composition. [Table 1]

[0099] The components in Table 1 are as follows. Base rubber: Polyisoprene rubber Nipol IR2200 manufactured by Nippon Zeon Co., Ltd. Silica: Evonik Degussa Ultrasil VN3 1,6-Bis(N,N-dibenzylthiocarbamoyldithio)hexane: Vulcuren manufactured by LANXESS Co., Ltd. Coumarone resin: Nitto Resin Coumarone G-90 manufactured by Nippon Paint Chemical Co., Ltd. Petroleum-based resin: Maruzen Petrochemical Co., Ltd., MARKAREZ M890A (dicyclopentadiene-based petroleum-based resin) Liquid polyisoprene rubber: Kuraray Kuraray LIR-50 Carbon black: Seast 3 (FEF grade) manufactured by Tokai Carbon Co., Ltd. Vulcanizing agent: 5% oil-treated powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator: Noccela NS (sulfenamide vulcanization accelerator) manufactured by Ouchi Shinko Chemical Co., Ltd. Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Tsubaki made by NOF Corporation Anti-aging agent 1: Kawaguchi Chemical Industry's Antage RD (polymer of 2,2,4-trimethyl-1,2-dihydroquinoline) Anti-aging agent 2: Nocrac MB (2-mercaptobenzimidazole) manufactured by Ouchi Shinko Chemical Co., Ltd.

[0100] As is clear from the results in Table 1, a damping rubber composition containing a base rubber having a polymerizable double bond, silica, and 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane, in which the amount of 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane is 0.5 parts by mass or more and 4.0 parts by mass or less per 100 parts by mass of the base rubber having a double bond, has excellent damping performance and suppresses load reduction in the range exceeding the maximum load strain. [Explanation of symbols]

[0101] 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: straight line, L2: perpendicular line, W: elastic strain energy, ΔW: absorbed energy amount, Keq: slope of straight line L1

[0102] A preferred embodiment (1) of the present invention is a damping rubber composition comprising a base rubber having a polymerizable double bond, silica, and 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane, the amount of 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane being 0.5 parts by mass or more and 4.0 parts by mass or less per 100 parts by mass of the base rubber having a polymerizable double bond.

[0103] A preferred embodiment (2) of the present invention is the damping rubber composition according to the embodiment (1), in which the base rubber having the polymerizable double bond contains a polyisoprene rubber.

[0104] A preferred embodiment (3) of the present invention is the damping rubber composition according to embodiment (1) or (2), in which the content of the polyisoprene-based rubber in the base rubber having the polymerizable double bond is 50% by mass or more and 100% by mass or less.

[0105] A preferred embodiment (4) of the present invention is the damping rubber composition according to any one of the embodiments (1) to (3), which contains 100 parts by mass or more and 180 parts by mass or less of silica per 100 parts by mass of the base rubber having the polymerizable double bond.

[0106] A preferred embodiment (5) of the present invention is a damping rubber composition according to any one of the embodiments (1) to (4), which contains, per 100 parts by mass of the base rubber having a polymerizable double bond, 0 part by mass or more and 2.5 parts by mass or less of a sulfur-based vulcanizing agent and 0.3 parts by mass or more and 2.5 parts by mass or less of a vulcanization accelerator.

[0107] A preferred embodiment (6) of the present invention is a damping rubber obtained by curing the damping rubber composition according to any one of the above embodiments (1) to (5).

[0108] A preferred embodiment (7) of the present invention is a viscoelastic damper comprising a damping rubber obtained by curing the damping rubber composition according to any one of the above embodiments (1) to (5).

Claims

1. A base rubber having a polymerizable double bond, silica, and Contains 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane, A damping rubber composition comprising a base rubber having a polymerizable double bond and a base rubber composition containing 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane in an amount of 0.5 parts by mass or more and 4.0 parts by mass or less based on 100 parts by mass of the base rubber having a polymerizable double bond.

2. 2. The damping rubber composition according to claim 1, wherein the base rubber having a polymerizable double bond contains a polyisoprene rubber.

3. 3. The damping rubber composition according to claim 2, wherein a content of the polyisoprene rubber in the base rubber having the polymerizable double bond is 50% by mass or more and 100% by mass or less.

4. 2. The damping rubber composition according to claim 1, further comprising 100 parts by mass or more and 180 parts by mass or less of silica per 100 parts by mass of the base rubber having the polymerizable double bond.

5. Relative to 100 parts by mass of the base rubber having a polymerizable double bond, A sulfur-based vulcanizing agent is 0 parts by mass or more and 2.5 parts by mass or less, The damping rubber composition according to claim 1, further comprising 0.3 parts by mass or more and 2.5 parts by mass or less of a vulcanization accelerator.

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

7. A viscoelastic damper comprising a damping rubber obtained by curing the damping rubber composition according to any one of claims 1 to 5.

Images