Damping rubber composition and viscoelastic damper

Abstract

To provide a damping rubber composition capable of forming a damping member which improves shear modulus while maintaining good processability and damping properties.SOLUTION: There is provided a damping rubber composition comprising a base rubber, silica and polyethylene, wherein the content of the silica is 80 pts.mass or more and 130 pts.mass or less based on 100 pts.mass of the base rubber and the density of the polyethylene is more than 925 kg / m3.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] In buildings such as houses and buildings, seismic isolation, vibration control, vibration damping, and vibration isolation means having vibration damping performance, such as viscoelastic dampers equipped with damping members (viscoelastic bodies), are installed to absorb vibration energy generated by earthquakes and other events. Damping rubber compositions are widely used as materials for forming the damping members. Conventionally, known methods for increasing the rigidity (shear modulus) of damping members include increasing the amount of filler in the damping rubber composition and adding a silane coupling agent to the damping rubber composition.

[0003] For example, Patent Document 1 discloses a high-damping rubber composition that contains rubber containing natural rubber and / or isoprene rubber, carbon black, silica, and rosin-modified phenol and / or rosin ester, in which the carbon black content is 20 to 80 parts by weight per 100 parts by weight of the rubber, and the silica content is 30 to 80 parts by weight per 100 parts by weight of the rubber.

[0004] Patent Document 2 discloses a high-damping rubber composition containing at least a rubber component and a metal rosinate, in which the content of the metal rosinate is 5 to 60 parts by mass per 100 parts by mass of the rubber component.

[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. [Prior art documents] [Patent documents]

[0006] [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 Summary of the Invention [Problem to be solved by the invention]

[0007] Increasing the amount of filler in the damping rubber composition increases the Mooney viscosity, making kneading difficult and prone to poor dispersion (i.e., poor processability). Also, adding a silane coupling agent to the damping rubber composition reduces damping properties.

[0008] The present invention has been made in view of the above circumstances, and has an object to provide a damping rubber composition that can form a damping member that improves shear modulus while maintaining good processability and damping properties. Another object of the present invention is to provide a viscoelastic damper that includes a damping member formed by curing the damping rubber composition. [Means for solving the problem]

[0009] The damping rubber composition of the present invention, which has been able to solve the above-mentioned problems, is a damping rubber composition containing a base rubber, silica, and polyethylene, wherein the content of the silica is 80 parts by mass or more and 130 parts by mass or less per 100 parts by mass of the base rubber, and the density of the polyethylene is 925 kg / m 3 It is characterized by being super. [Effects of the Invention]

[0010] By using the damping rubber composition of the present invention, it is possible to form a damping member having a high shear modulus while maintaining good processability and damping properties. According to the present invention, a viscoelastic damper having a high shear modulus while maintaining good processability and damping properties can be obtained. [Brief explanation of the drawings]

[0011] [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

[0012] <Dampening Rubber Composition> The damping rubber composition of the present invention is a damping rubber composition containing a base rubber, silica, and polyethylene, wherein the content of the silica is 80 parts by mass or more and 130 parts by mass or less per 100 parts by mass of the base rubber, and the density of the polyethylene is 925 kg / m 3 It is characterized by being super.

[0013] By adjusting the silica content to a specific range, it is possible to obtain a damping member that has excellent shear modulus and damping properties while also having good processability. 3 Polyethylenes with a hardness exceeding 1000 kJ / cm2 have high hardness. By using such hard polyethylene, the shear modulus of the resulting damping member can be increased. Furthermore, since the polyethylene has a melting point near the mixing temperature of the damping rubber composition (usually 130°C to 150°C), good processability can be maintained without increasing the Mooney viscosity during mixing. The polyethylene has almost no effect on the high damping properties provided by silica. Therefore, according to the present invention, the shear modulus can be increased while maintaining good processability and damping properties.

[0014] The damping rubber composition of the present invention will now be described. (Base rubber) The damping rubber composition of the present invention contains a base rubber, which is preferably a rubber having a polymerizable carbon-carbon double bond in its main chain.

[0015] The base rubber preferably contains at least one rubber selected from the group consisting of polyisoprene-based rubber and polybutadiene-based rubber.

[0016] The polyisoprene-based rubber is not particularly limited as long as it is a rubber having structural units derived from isoprene (preferably a rubber having mainly structural units derived from isoprene). Examples of the polyisoprene-based rubber include natural rubber (NR) and synthetic rubber. Natural rubber is derived from rubber-containing plants and contains pure cis-1,4-polyisoprene. Synthetic polyisoprene-based rubber is synthesized by polymerizing a monomer containing isoprene (preferably a monomer containing isoprene as the main component). The natural rubber and synthetic polyisoprene-based rubber may be modified rubber. These polyisoprene-based rubbers may be used alone or in combination.

[0017] The natural rubber may be a CV grade, in which the rubber viscosity is stabilized by adding a viscosity stabilizer or the like to the raw latex, or a non-CV grade, in which the rubber viscosity is not stabilized. These may be used alone or in combination of two or more. Of these, the CV grade, which has a particularly stable viscosity, is preferred. The natural rubber may be either SMR (standard Malaysian rubber) or SVR (standard Vietnamese rubber).

[0018] As the natural rubber, technically specified rubbers (TSR) and visually specified rubbers (Ribbed Smoked Sheets (RSS)) are preferred.

[0019] Natural rubber also includes modified natural rubbers such as epoxidized natural rubber, methacrylic acid-modified natural rubber, halogen-modified natural rubber, deproteinized natural rubber, maleic acid-modified natural rubber, sulfonic acid-modified natural rubber, and styrene-modified natural rubber.

[0020] Examples of the synthetic polyisoprene rubber include polyisoprene rubber (IR) and copolymer rubber of isoprene and other monomer components.

[0021] Examples of other monomer components that can constitute the synthetic polyisoprene rubber include butadiene, styrene, ethylene, propylene, acrylonitrile, chloroprene, etc. These other monomer components may be used alone or in combination of two or more.

[0022] The synthetic polyisoprene rubber preferably contains 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more of structural units derived from isoprene, with the upper limit of the isoprene-derived structural units being 100% by mass.

[0023] Among the synthetic polyisoprene rubbers, polyisoprene rubber (IR) is preferred, and high cis-1,4-polyisoprene rubber containing 90% by mass or more (preferably 95% by mass or more) of cis-1,4-bonds is more preferred. Use of high cis-1,4-polyisoprene rubber improves damping properties in the low strain range.

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

[0025] The Mooney viscosity (ML 1+4(100°C)) is preferably 40 or more, more preferably 45 or more, even more preferably 50 or more, and is preferably 120 or less, more preferably 110 or less, even more preferably 100 or less. When the Mooney viscosity of the polyisoprene rubber is within the above range, the effects of the present invention can be more effectively obtained. Note that the Mooney viscosity (ML 1+4 (100°C)) is a value measured in accordance with JIS K6300 using an L rotor, with a preheating time of 1 minute, rotor rotation time of 4 minutes, and at 100°C.

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

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

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

[0029] The polybutadiene rubber preferably contains 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more of butadiene-derived structural units, with the upper limit being 100% by mass.

[0030] Among the polybutadiene rubbers, polybutadiene rubber (BR) is preferred, and high-cis-1,4-polybutadiene rubber containing 90% by mass or more (preferably 95% by mass or more) of cis-1,4-bonds is more preferred. High-cis-1,4-polybutadiene rubber has smaller fluctuations in physical properties due to temperature (especially at low temperatures). By using high-cis-1,4-polybutadiene rubber, it is possible to reduce the temperature dependence of the damping property and shear modulus of the damping member in the low strain range.

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

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

[0033] The base rubber may contain other rubber components in addition to the polyisoprene-based rubber and / or polybutadiene-based rubber. Examples of such other rubber components include butyl rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, and modified rubbers thereof. These other rubber components may be used alone or in combination of two or more.

[0034] The total content of polyisoprene-based rubber and / or polybutadiene-based rubber in the base rubber is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more. Most preferably, the base rubber contains only polyisoprene-based rubber and / or polybutadiene-based rubber.

[0035] When polyisoprene-based rubber and polybutadiene-based rubber are used in combination as the base rubber, the mass ratio of the polyisoprene-based rubber to the polybutadiene-based rubber (polyisoprene-based rubber / polybutadiene-based rubber) is preferably 0.5 or more, more preferably 1.0 or more, and even more preferably 1.2 or more, and is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less.

[0036] The rubber components (polyisoprene rubber, polybutadiene rubber, and other rubber components) contained in the damping rubber composition of the present invention may be either oil-extended types in which extender oil is added, or non-oil-extended types in which extender oil is not added. When an oil-extended type is used, the rubber content and mass ratio are values ​​calculated based on the rubber content excluding the extender oil.

[0037] The base rubber component contained in the damping rubber composition of the present invention preferably exhibits a solid state at 25° C. In other words, the base rubber of the present invention preferably does not contain a liquid rubber that is normally used as a softener and exhibits a liquid state at 25° C.

[0038] (silica) The damping rubber composition of the present invention contains silica, which may be, for example, synthetic silica having a porous structure, which is obtained by chemically reacting silica sand as a raw material.

[0039] The 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.

[0040] Specific examples of the silica include commercially available products such as the Ultrasil (registered trademark) series manufactured by EVONIC (for example, Ultrasil VN3) and the Nipsil (registered trademark) series manufactured by Tosoh Silica Corporation (for example, Nipsil VN3).

[0041] The BET specific surface area of ​​the silica is 130 m 2 / g or more, and 150m 2 / g or more is more preferable, and 170m 2 / g or more is more preferable, and 2 / g or less, and 2 / g or less is more preferable, and 280m 2 / g or less is more preferable. The BET specific surface area is a value measured by a gas phase adsorption method using nitrogen gas as the adsorption gas.

[0042] The silica content, per 100 parts by mass of the base rubber, is preferably 80 parts by mass or more, more preferably 82 parts by mass or more, and even more preferably 85 parts by mass or more, and is preferably 135 parts by mass or less, more preferably 133 parts by mass or less, and even more preferably 130 parts by mass or less. If the silica content is 80 parts by mass or more, the effect of silica in improving shear modulus and damping properties is fully exhibited, while if it is 135 parts by mass or less, the rubber composition is easily kneaded and processability is improved.

[0043] (polyethylene) The damping rubber composition of the present invention has a density of 925 kg / m 3The polyethylene is preferably in the form of powder or granules, more preferably in the form of fine particles.

[0044] Density is 925 kg / m 3 Polyethylenes with a density of over 925 kg / m have high hardness. By using such hard polyethylene, the shear modulus of the resulting damping member can be increased. Furthermore, since the polyethylene has a melting point near the mixing temperature of the damping rubber composition (usually 130°C to 150°C), good processability can be maintained without increasing the Mooney viscosity during mixing. Furthermore, the polyethylene has almost no effect on the high damping performance improvement effect of silica. Therefore, when the density is 925 kg / m, 3 The use of polyethylene with a high shear modulus allows for a high shear modulus while maintaining good processability and damping properties.

[0045] The density of the polyethylene used in the present invention is 925 kg / m 3 More preferably, it is greater than 930 kg / m 3 More preferably, it is 933 kg / m or more. 3 More preferably, it is 935 kg / m or more. 3 The upper limit of the density of the polyethylene is not particularly limited, but is preferably 975 kg / m or more. 3 It is preferable that the saturation is 970 kg / m or less. 3 More preferably, it is 965 kg / m or less. 3 It is more preferable that the density of the polyethylene is 975 kg / m or less. 3 This is because, if the density is not more than 100%, the shear modulus can be increased while maintaining good processability and damping properties. The polyethylenes of each density may be used alone or in combination of two or more kinds.

[0046] In the present invention, the density is 940 kg / m 3 High density polyethylene (HDPE) is polyethylene with a density of 925 kg / m 3 Super, 940kg / m 3The following polyethylene is considered medium density polyethylene (MDPE) and has a density of 911 kg / m 3 Super, 925kg / m 3 The following polyethylene may be referred to as low-density polyethylene (LDPE). The density of the polyethylene in the present invention can be measured in accordance with JIS K6922-1.

[0047] As long as the effect of the present invention is not impaired, the density is 925 kg / m 3 In addition to polyethylene, which is ultra-high density, the density is 925 kg / m 3 In this case, polyethylene with a density of 925 kg / m or less may be used in combination. 3 Polyethylene with a density of 925kg / m 3 The density is 925 kg / m or less in a total of 100 mass% of polyethylene. 3 The polyethylene content is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. 3 It is most preferred that the polymer does not contain polyethylene, which is:

[0048] The density is 925 kg / m 3 The melting point of the polyethylene is not particularly limited as long as it is in the vicinity of the kneading temperature of the damping rubber composition (usually 130°C to 150°C), but is preferably (kneading temperature - 20°C) or higher, more preferably (kneading temperature - 15°C) or higher, even more preferably (kneading temperature - 10°C) or higher, and is preferably the kneading temperature or lower, more preferably (kneading temperature - 5°C) or lower. Specifically, for example, when the density is 925 kg / m 3 The melting point of the polyethylene having a density of more than 925 kg / m is preferably 110°C or higher, more preferably 115°C or higher, and even more preferably 120°C or higher, and is preferably 150°C or lower, more preferably 145°C or lower, and even more preferably 140°C or lower. 3When the melting point of the polyethylene is within the above range, good processability can be more easily maintained. In the present invention, the melting point of the polyethylene is based on JIS K7121.

[0049] Density is 925 kg / m 3 A specific example of polyethylene having a density of over 938 kg / m is MIPERON (registered trademark) PM-200 manufactured by Mitsui Chemicals, Inc. 3 , melting point: 136°C], XM-220 [density: 937 kg / m 3 ], XM-221U [density: 937kg / m 3 ], XM-330 [Density: 937kg / m 3 ], Sumitomo Seika Flow Beads HE-3040 [density: 960 kg / m 3 , melting point: 130°C].

[0050] The density is 925 kg / m 3 The polyethylene content is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 5 parts by mass or more, and 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, per 100 parts by mass of the base rubber. 3 When the content of polyethylene is more than 1 part by mass or more, the rigidity can be increased, and when it is 30 parts by mass or less, deterioration of processability can be prevented.

[0051] The polyethylene referred to in the present invention includes a homopolymer made of ethylene, and a copolymer of ethylene (mainly ethylene) and an α-olefin (for example, an α-olefin having 3 to 8 carbon atoms). When the polyethylene is a copolymer, the mass proportion of repeating units derived from ethylene in the copolymer is preferably 60 mass% or more, more preferably 80 mass% or more, and even more preferably 90 mass% or more.

[0052] (vulcanizing agent) The damping rubber composition of the present invention preferably further contains a vulcanizing agent. 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.

[0053] Specific examples of the vulcanizing agent include commercially available products such as 5% oil-treated powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

[0054] The content of the vulcanizing agent is preferably at least 0.5 parts by weight, more preferably at least 0.8 parts by weight, and even more preferably at least 1.0 part by weight, and is preferably at most 3.0 parts by weight, more preferably at most 2.5 parts by weight, and even more preferably at most 2.0 parts by weight, per 100 parts by weight of the base rubber. When the content of the vulcanizing agent is within the above range, vulcanization is favorable while suppressing the occurrence of blooming. 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.

[0055] (Vulcanization accelerator) The damping rubber composition of the present invention preferably further contains a vulcanization accelerator.

[0056] 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.

[0057] Specific examples of the vulcanization accelerator include the Accel (registered trademark) series (e.g., Accel CZ, Accel TET) manufactured by Kawaguchi Chemical Industry Co., Ltd., and the Noccela (registered trademark) series (e.g., Noccela NS, Noccela TBT-N) manufactured by Ouchi Shinko Chemical Co., Ltd.

[0058] The content of the vulcanization accelerator, relative to 100 parts by mass of the base rubber, is preferably 0.3 parts by mass or more, more preferably 0.4 parts by mass or more, and even more preferably 0.5 parts by mass or more, and is preferably 3.0 parts by mass or less, more preferably 2.5 parts by mass or less, and even more preferably 2.0 parts by mass or less. When the content of the vulcanization accelerator is within the above range, the vulcanization acceleration is good and the occurrence of blooming can be suppressed.

[0059] (vulcanization aid) The damping rubber composition of the present invention preferably further contains a vulcanization aid. Examples of the vulcanization aid include metal compounds such as zinc oxide, and fatty acids such as stearic acid, oleic acid, and cottonseed fatty acid. These vulcanization aids may be used alone or in combination of two or more.

[0060] 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.

[0061] 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 properties of the rubber composition will be better.

[0062] 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 4.5 or less, and even more preferably 4 or less. If the mass ratio of the metal compound to the fatty acid is within the above range, the vulcanization properties of the rubber composition will be even better.

[0063] (tackifier) The damping rubber composition of the present invention preferably further contains a tackifier. Examples of the tackifier include petroleum-based resins, coumarone-based resins, and terpene-based resins. These tackifiers may be used alone or in combination of two or more.

[0064] Petroleum-based resins are resins obtained by polymerizing or copolymerizing petroleum fractions obtained as by-products when petroleum such as naphtha is thermally cracked to produce olefins such as ethylene. Note that the raw materials for petroleum-based resins do not necessarily have to be petroleum fractions, and may contain chemically synthesized unsaturated compounds.

[0065] Examples of the petroleum fraction include aliphatic olefins having 4 to 10 carbon atoms, aliphatic diolefins having 4 to 10 carbon atoms, and aromatic compounds having 8 or more carbon atoms and an olefinically unsaturated bond.

[0066] Examples of the aliphatic olefins having 4 to 10 carbon atoms include butene, pentene, hexene, and heptene. Examples of the aliphatic diolefins having 4 to 10 carbon atoms include butadiene, pentadiene, isoprene, cyclopentadiene, dicyclopentadiene, and methylpentadiene. Examples of the aromatic compounds having 8 or more carbon atoms and an olefinically unsaturated bond include styrene, α-methylstyrene, β-methylstyrene, vinyltoluene, vinylxylene, indene, methylindene, and ethylindene.

[0067] Examples of the chemically synthesized unsaturated compounds include cyclopentadiene and dicyclopentadiene (DCPD).

[0068] Examples of 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; and dicyclopentadiene-aromatic copolymer petroleum resins obtained by copolymerizing cyclopentadiene or dicyclopentadiene with aromatic compounds having olefinic unsaturated bonds. Aromatic petroleum resins also include styrene resins obtained by polymerizing styrene compounds (styrene, α-methylstyrene, β-methylstyrene).

[0069] Furthermore, hydrogenated petroleum resins can also be used, which are obtained by adding hydrogen atoms to polymers obtained by polymerizing the petroleum fractions or chemically synthesized unsaturated compounds. By adding hydrogen atoms, the double bonds in the molecule are hydrogenated. The hydrogenated product can 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.

[0070] 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.

[0071] The petroleum resin is preferably at least one resin selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, aliphatic-aromatic copolymer petroleum resins, dicyclopentadiene petroleum resins, dicyclopentadiene-aromatic copolymer petroleum resins, hydrogenated aliphatic petroleum resins, hydrogenated aromatic petroleum resins, hydrogenated aliphatic-aromatic copolymer petroleum resins, hydrogenated dicyclopentadiene petroleum resins, and hydrogenated dicyclopentadiene-aromatic copolymer petroleum resins.

[0072] Specific examples of the petroleum-based resins include commercially available products such as the Quinton (registered trademark) 1000 series (e.g., Quinton 1105, Quinton 1920, Quinton 2940) and 100 series (e.g., Quinton E200SN) manufactured by Zeon Corporation, the Petcol (registered trademark) series (e.g., Petcol 120, Petcol 130, Petcol LX) and Petrotack (registered trademark) series (e.g., Petrotack 60, Petrotack 70) manufactured by Tosoh Corporation, the Struktol (registered trademark) series (e.g., Struktol 40MS, Struktol 60NS) manufactured by Struktol, and the Marucarets (registered trademark) M series (e.g., Marucarets M-890A) manufactured by Maruzen Petrochemical Co., Ltd.

[0073] The coumarone-based resin is a resin obtained by polymerizing coumarone compounds as monomer components and has structural units derived from coumarone compounds. Examples of the coumarone compounds include coumarone and methylcoumarone. The coumarone-based resin is preferably a coumarone-indene resin. The coumarone-indene resin is a resin obtained by copolymerizing coumarone compounds and indenes as monomer components and has structural units derived from coumarone compounds and structural units derived from indenes. Examples of the indenes include indene and methylindene. The total content of the structural units derived from coumarone compounds and indenes in the coumarone-indene resin is preferably 50% by mass or more. The content of the structural units derived from coumarone compounds in the coumarone-indene resin is preferably 1% by mass to 20% by mass. The content of the structural units derived from indenes in the coumarone-indene resin is preferably 40% by mass to 95% by mass. The coumarone-indene resin may contain monomer components other than coumarone compounds and indenes. Examples of the other monomer components include styrene, vinyltoluene, and dicyclopentadiene.

[0074] Specific examples of the coumarone 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).

[0075] The terpene resin is a resin having structural units mainly derived 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 terpene resins may be used alone or in combination of two or more.

[0076] The terpene compounds are hydrocarbons and their oxygen-containing derivatives represented by the formula (C5H8)n, and are 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.

[0077] 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.

[0078] Specific examples of the terpene resin include commercially available products such as the Sylvatraxx (registered trademark) series (for example, Sylvatraxx 4150, Sylvatraxx 4125) and the Sylvares (registered trademark) series (for example, Sylvares TR B115, Sylvares TR M1115) manufactured by Kraton.

[0079] As the tackifier, it is particularly preferable to use a petroleum-based resin or a coumarone-based resin, and it is more preferable to use a combination of a petroleum-based resin and a coumarone-based resin. When a petroleum-based resin and a coumarone-based resin are used in combination, the mass ratio thereof (petroleum-based resin / coumarone-based resin) is preferably 1 or more, more preferably 1.5 or more, even more preferably 2 or more, preferably 5 or less, more preferably 4.5 or less, and even more preferably 4 or less. This is because, if the mass ratio (petroleum-based resin / coumarone-based resin) is within the above range, sticking to the roll during processing can be suppressed.

[0080] The amount of the tackifier, relative to 100 parts by mass of the base rubber, is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 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, if the amount of the tackifier is within the above range, deterioration of the temperature dependency of rigidity is suppressed.

[0081] (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 a silylating agent, an antioxidant, a filler other than silica, a plasticizer, and the like, selected appropriately within the range that does not impair the object of the present invention.

[0082] [Silylating Agent] Examples of the silylating agent include alkyl-type silylating agents such as propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane, and decyltriethoxysilane; and phenyl-type silylating agents such as phenyltrimethoxysilane and phenyltriethoxysilane. These silylating agents may be used alone or in combination of two or more.

[0083] Specific examples of the silylating agent include commercially available products such as KBE-3033, KBE-3063, KBM-3103C, and KBE103 manufactured by Shin-Etsu Chemical Co., Ltd.

[0084] The amount of the silylating agent is preferably 15 to 30 parts by mass per 100 parts by mass of the base rubber. If the amount of the silylating agent is within this range, the dispersibility of silica in the base rubber can be improved without causing a decrease in the performance of the damping rubber member.

[0085] [Anti-aging agent] Examples of the antiaging agent include various antiaging agents such as benzimidazole-based, quinone-based, polyphenol-based, and amine-based antiaging agents. These antiaging agents may be used alone or in combination of two or more. Among these, benzimidazole-based antiaging agents are particularly preferred.

[0086] Specific examples of the benzimidazole-based antioxidant include commercially available products such as the Nocrac (registered trademark) series (for example, Nocrac MB) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0087] The content of the antioxidant is preferably 0.5 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the base rubber. When the content of the antioxidant is within this range, the rubber composition has a good anti-aging effect.

[0088] [Fillers other than silica] Examples of fillers other than silica include inorganic fillers such as carbon black, calcium carbonate, magnesium carbonate, barium sulfate, talc, and clay. These fillers may be used alone or in combination of two or more. Among these, carbon black is particularly preferred.

[0089] Carbon black can be produced by, for example, pyrolysis or incomplete combustion of hydrocarbons such as petroleum-based 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.

[0090] Specific examples of the carbon black include commercially available products such as the Seast series (for example, Seast SO) manufactured by Tokai Carbon Co., Ltd.

[0091] The content of the filler is preferably 1 part by weight or more and 30 parts by weight or less per 100 parts by weight of the base rubber.

[0092] [Plasticizer] Examples of the plasticizer include orthophosphate ester-based plasticizers such as trimethyl phosphate (TMP), triethyl phosphate (TEP), tributyl phosphate (TBP), tris(2-ethylhexyl) phosphate (TOP), triphenyl phosphate (TPP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), and cresyl diphenyl phosphate (CDP); phthalate ester-based plasticizers such as dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and bis(2-ethylhexyl) phthalate (DOP); and dibutyl azide-based plasticizers such as dimethyl azide (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and bis(2-ethylhexyl) phthalate (DOP). Examples of suitable plasticizers include adipate esters such as dibutyl sebacate (DBA), diisobutyl adipate (DIBA), bis(2-ethylhexyl) adipate (DOA), diisononyl adipate (DINA), diisodecyl adipate (DIDA), bis[2-(2-butoxyethoxy)ethyl] adipate (BXA-N), and bis[2-(2-butoxyethoxy)ethyl] adipate (BXA-R); sebacate esters such as dibutyl sebacate (DBS) and bis(2-ethylhexyl) sebacate (DOS); and ricinoleate esters such as methyl acetyl ricinoleate (MAR-N). These plasticizers may be used alone or in combination.

[0093] Specific examples of the plasticizer include various plasticizers for rubber applications manufactured by Daihachi Chemical Industry Co., Ltd.

[0094] Liquid rubber can also be used as a plasticizer. Examples of the liquid rubber include liquid isoprene rubber, liquid styrene isoprene rubber, liquid styrene butadiene rubber, liquid acrylonitrile butadiene rubber, liquid butadiene rubber, and liquid chloroprene rubber. These liquid rubbers may be used alone or in combination of two or more. Liquid rubbers are distinguished from the base rubber (which is solid at 25°C) in that they are liquid at room temperature (25°C).

[0095] Specific examples of the liquid rubber include commercially available products such as the LIR series (for example, LIR50), LBR series, and L-SBR series manufactured by Kuraray Co., Ltd.

[0096] The amount of the plasticizer, relative to 100 parts by mass of the base rubber, is preferably 15 parts by mass or more, more preferably 18 parts by mass or more, and even more preferably 20 parts by mass or more, and is preferably 35 parts by mass or less, more preferably 32 parts by mass or less, and even more preferably 30 parts by mass or less. If the amount of the plasticizer is 15 parts by mass or more, the kneading of the rubber composition becomes easier, and if it is 35 parts by mass or less, the discharge of the kneaded rubber composition becomes easier.

[0097] The damping rubber composition of the present invention can be prepared, for example, by kneading the base rubber, silica, polyethylene, and, if necessary, the vulcanizing agent, vulcanization accelerator, vulcanization aid, tackifier, and other components. 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.

[0098] The kneading temperature for the damping rubber composition is not particularly limited, but is preferably 130°C to 150°C.

[0099] <Damping rubber> The present invention includes a damping rubber obtained by curing the damping rubber composition of the present invention. The damping rubber of the present invention can be obtained, for example, by pressing the damping rubber composition after kneading under conditions of 130°C to 170°C for 20 minutes to 10 hours, thereby simultaneously molding and vulcanizing the composition.

[0100] The damping rubber of the present invention has a high shear modulus while maintaining good processability and damping properties, and can be suitably used, for example, as a vibration-damping material for absorbing vibration energy generated by earthquakes and the like.

[0101] <Viscoelastic damper> The present invention includes a viscoelastic damper that includes the damping rubber of the present invention as a damping member. The viscoelastic damper of the present invention has an improved shear modulus while maintaining good processability and damping properties. For example, it can be suitably used as a viscoelastic damper (particularly a viscoelastic damper installed in buildings) for absorbing vibration energy generated by earthquakes and the like. [Example]

[0102] 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.

[0103] [Evaluation method] <Processability test> The components of the rubber composition were mixed in an internal mixer at 150°C, and the processability was evaluated as follows: if the process from mixing to discharging went smoothly without any problems, it was marked as "○", if it was possible but with some difficulty, it was marked as "△", and if it was not possible, it was marked as "×". Products rated as "○" or "△" were considered to have passed the test.

[0104] <Displacement test> (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 150°C while being pressurized in the lamination direction to crosslink the rubber composition forming flat plate 1 and vulcanize-bond flat plate 1 to the two steel plates 2, thereby producing specimen 3 as a model of a damping member.

[0105] (Displacement test) Two specimens 3 were prepared as shown in Figure 2(a). Each specimen 3 was fixed to a central fixture 4 with bolts via one of the steel plates 2, and one left and one right fixture 5 was fixed to each of the other steel plates 2 of each specimen 3 with bolts. The central fixture 4 was then fixed to an upper fixed arm 6 of a testing machine (not shown) with bolts via joints 7, and the two left and right fixtures 5 were fixed to a lower movable platen 8 of the testing machine with bolts via joints 9. Each specimen 3 was fixed as described above with the two parallel sides of the plate 1 aligned parallel to the displacement direction described below. The plate 1 was then repeatedly subjected to strain deformation, i.e., vibration, with the following operations (I) and (II) considered as one cycle. A hysteresis loop H (see Figure 3) was then 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) when the plate 1 was subjected to repeated strain deformation, i.e., vibration. (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 above state, the movable platen 8 is displaced so as to be pulled down in the direction opposite to the direction of the fixed arm 6, as shown by the white arrow in Figure 2(b), to return to the state shown in Figure 2(a).

[0106] The measurements were carried out in an environment at a temperature of 23°C, with the above operations (I) and (II) repeated three times to determine the value at the third cycle. 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 thickness direction and the direction perpendicular to the thickness direction of the flat plate 1 was 100% of the thickness of the flat plate 1.

[0107] From the hysteresis loop H in Figure 3 obtained by measurement, the equivalent shear modulus Geq (N / mm 2 ) was sought.

[0108]

number

[0109] In the formula, Keq (N / mm) is the slope of the straight line L1 shown by the thick solid line in FIG. 3, which connects the maximum displacement point and the minimum displacement point of the hysteresis loop H, T (mm) is the thickness of the flat plate 1, and A (mm 2 ) is the cross-sectional area of ​​plate 1.

[0110] Furthermore, the equivalent damping constant heq was calculated from the hysteresis loop H in FIG. 3 using the following formula (2).

[0111]

number

[0112] In the formula, ΔW is the amount of absorbed energy represented by the total surface area of ​​hysteresis loop H, which is shown by the diagonal lines in Figure 3, and W is the elastic strain energy represented by the surface area of ​​the triangle region surrounded by line L1, the horizontal axis of the graph, and a perpendicular line L2 drawn from the intersection of line L1 and hysteresis loop H to the horizontal axis of the graph, which is shown by the hatched lines in the same figure.

[0113] (evaluation) The relative value of the equivalent shear modulus Geq of each rubber composition was determined when the equivalent shear modulus Geq of rubber composition No. 1 was set to 100. A relative value of Geq of 104 or more was evaluated as ◯ (pass), and a value of less than 104 was evaluated as "×" (fail). In addition, the relative value of the equivalent damping constant heq of each example was determined when the equivalent damping constant heq of rubber composition No. 1 was set to 100. A relative value of heq of 98 or more was evaluated as ◯ (pass), and a value of less than 98 was evaluated as "×" (fail).

[0114] Each component shown in Tables 1 and 2 was kneaded using an internal kneader to prepare a rubber composition.

[0115] [Table 1]

[0116] [Table 2]

[0117] The components in Tables 1 and 2 are as follows: Polyisoprene rubber: Nipol IR2200 (Mooney viscosity (ML)) manufactured by Nippon Zeon Co., Ltd. 1+4 (100℃):82) High-density polyethylene: Sumitomo Seika Flow Beads HE-3040 (density: 960 kg / m 3 , melting point: 130℃) Medium-density polyethylene: Mipelon PM-200 (density: 938 kg / m) manufactured by Mitsui Chemicals 3 , melting point: 136℃) Low-density polyethylene: Flow Beads CL-2080 (density: 920 kg / m) manufactured by Sumitomo Seika Chemicals 3 , melting point: 105℃) Silica: EVONIC Ultrasil VN3 Silylating agent: Shin-Etsu Chemical KBE103 Carbon black: Tokai Carbon Co., Ltd., Seast SO (FEF) Plasticizer (softener): Kuraray LIR50 Anti-aging agent: Nocrac MB (benzimidazole-based anti-aging agent) manufactured by Ouchi Shinko Chemical Co., Ltd. Stearic acid: NOF Corporation Tsubaki Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Vulcanizing agent: 5% oil-treated powder sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Sulfenamide vulcanization accelerator: Noccela NS manufactured by Ouchi Shinko Chemical Co., Ltd. Thiuram vulcanization accelerator: Noccela TBT-N manufactured by Ouchi Shinko Chemical Co., Ltd. Petroleum-based resin: Quinton 1105 (dicyclopentadiene-based) manufactured by Nippon Zeon Co., Ltd. Coumarone resin: Kumarone G-90 (coumarone-indene type) knit resin manufactured by Nitto Chemical Co., Ltd.

[0118] As is clear from the results in Tables 1 and 2, the damping rubber composition contains base rubber, silica, and polyethylene, and the content of the silica is 80 parts by mass or more and 130 parts by mass or less per 100 parts by mass of the base rubber, and the density of the polyethylene is 925 kg / m 3 The damping rubber composition of the present invention, which has a shear modulus of greater than 100%, can be formed into a damping member having a high shear modulus while maintaining good processability and damping properties. [Explanation of symbols]

[0119] 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

[0120] A preferred embodiment (1) of the present invention is a damping rubber composition containing a base rubber, silica, and polyethylene, wherein the content of the silica is 80 parts by mass or more and 130 parts by mass or less per 100 parts by mass of the base rubber, and the density of the polyethylene is 925 kg / m 3 The damping rubber composition is characterized in that the damping rubber composition has a modulus of at least 100%.

[0121] A preferred embodiment (2) of the present invention is the damping rubber composition of the embodiment (1) in which the base rubber contains at least one rubber selected from the group consisting of polyisoprene-based rubber and polybutadiene-based rubber.

[0122] In a preferred embodiment (3) of the present invention, the density of the polyethylene is 940 kg / m 3 The damping rubber composition of embodiment (1) or (2) is above.

[0123] A preferred embodiment (4) of the present invention is the damping rubber composition according to any one of the embodiments (1) to (3), wherein the content of the polyethylene is 1 part by mass or more and 30 parts by mass or less per 100 parts by mass of the base rubber.

[0124] A preferred embodiment (5) of the present invention is the damping rubber composition according to any one of the above embodiments (1) to (4), which further contains a tackifier.

[0125] A preferred embodiment (6) of the present invention is a damping rubber obtained by curing the damping rubber composition of any one of the above embodiments (1) to (5).

[0126] A preferred embodiment (7) of the present invention is a viscoelastic damper including a damping member formed by curing the damping rubber composition according to any one of the above embodiments (1) to (5).

Claims

1. A damping rubber composition containing a base rubber, silica, and polyethylene, the amount of silica is 80 parts by weight or more and 130 parts by weight or less per 100 parts by weight of the base rubber, The density of the polyethylene is 925 kg / m ３ The damping rubber composition is characterized in that the damping rubber composition has a viscosity of 1000 MPa or more.

2. 2. The damping rubber composition according to claim 1, wherein the base rubber contains at least one rubber selected from the group consisting of polyisoprene-based rubber and polybutadiene-based rubber.

3. The density of the polyethylene is 940 kg / m ３ The damping rubber composition according to claim 1, wherein the modulus is greater than 1 / 2.

4. 2. The damping rubber composition according to claim 1, wherein the content of the polyethylene is 1 part by mass or more and 30 parts by mass or less per 100 parts by mass of the base rubber.

5. The damping rubber composition according to claim 1, further comprising a tackifier.

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 member formed by curing the damping rubber composition according to any one of claims 1 to 5.

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