WO2020179655A1 - Rubber composition for vibration damping rubber, and vibration damping rubber product - Google Patents

Abstract

The present invention provides a rubber composition for a vibration damping rubber, which contains, as a rubber component, at least a styrene butadiene rubber (I) that has a weight average molecular weight (Mw) of 700,000 or more in terms of polystyrene, while also containing a liquid styrene butadiene rubber (II) that has a weight average molecular weight of 12,000 or less in terms of polystyrene and a carbon black that serves as a filler, wherein: the total vinyl bond content in component (I) and component (II) is 25% by mass or more relative to a total of 100% by mass of component (I) and component (II); and the added amount of the carbon black is more than 40 parts by mass but not more than 110 parts by mass relative to 100 parts by mass of the rubber component. This rubber composition for vibration damping rubber exhibits high durability not only in a low loss region but also in a high loss region, and exhibits low dynamic magnification.

Description

Rubber composition for anti-vibration rubber and anti-vibration rubber product

The present invention is a rubber composition for anti-vibration rubber used in anti-vibration rubber products for vehicles, anti-vibration rubber products for railways, air springs, and particularly anti-vibration rubber products for automobiles such as torsional dampers, engine mounts, and muffler hangers. Regarding

　Anti-vibration rubber products are placed in various vehicles, such as automobiles, at locations that generate vibration and noise in order to improve passenger comfort. In order to reduce the intrusion of vibration and noise into the room, for example, for an engine that is the main source of vibration and noise, anti-vibration rubber is used for components such as torsional dampers, engine mounts, and muffler hangers. This absorbs the vibration when the engine is driven, and reduces the intrusion of vibration and noise into the room and the diffusion of noise to the surrounding environment.

The anti-vibration rubber used for such an application is interposed for a member constituting a vibration or shock transmission system, and has both excellent physical properties with excellent anti-vibration property and sufficient durability, and especially for vibration absorption. From the viewpoint, rubber loss (tan δ) is required to be high, that is, high loss property is required (for example, Patent Document 1).

As a method for increasing the loss of the anti-vibration rubber, for example, a technique of highly filling a rubber composition with a filler or a resin can be considered. However, although high lossability can be achieved by high filling of fillers and resins, durability and settling resistance tend to deteriorate. Therefore, it is difficult to achieve both high loss property and durability. Further, when the rubber composition is highly filled with a filler or a resin, the dynamic magnification is significantly deteriorated.

Other related prior art documents include tire rubber compositions described in Patent Document 2 below.

JP-A-9-176387 JP, 2009-1721, A

The present invention has been made in view of the above circumstances, and it is possible to realize high durability not only in the low loss region but also in the high loss region, and to obtain a good low dynamic ratio. The purpose is to provide vibration rubber products.

As a result of diligent studies to achieve the above object, the present inventor contains at least styrene-butadiene rubber (I) having a polystyrene-equivalent weight average molecular weight (Mw) of 700,000 or more as a rubber component and is polystyrene-equivalent. In a rubber composition containing liquid styrene-butadiene rubber (II) having a weight average molecular weight (Mw) of 12,000 or less and carbon black as a filler, the total amount of vinyl bonds in the above components (I) and (II). Is used in a specific range, and by blending carbon black used as a filler in a specific range, it is possible to achieve high durability not only in the low loss region but also in the high loss region, and maintain a good low dynamic ratio. I found that I could do it.

That is, if a large amount of resin is added to the rubber composition for vibration-proof rubber in order to obtain a high loss property that cannot be achieved only by the filler, the durability (for example, crack resistance) and the dynamic ratio are greatly reduced. Therefore, by blending a specific liquid rubber instead of a resin, it is possible to increase the entanglement of molecular chains and enhance energy dissipation, thereby achieving both durability and dynamic magnification while maintaining high loss properties. Do you get it. The present invention has been completed based on such findings.

Therefore, the present invention provides the following rubber composition for vibration damping rubber and vibration damping rubber product.
1. Filled with liquid styrene-butadiene rubber (II) containing at least styrene-butadiene rubber (I) having a polystyrene-equivalent weight average molecular weight of 700,000 or more and having a polystyrene-equivalent weight average molecular weight of 12,000 or less as a rubber component. An anti-vibration rubber composition containing carbon black as an agent, wherein the total amount of vinyl bond content in the above-mentioned component (I) and the above-mentioned (II) is 100 mass in total of the above-mentioned (I) component and the above (II) component. The rubber composition for vibration-proof rubber is 25% by mass or more with respect to%, and the blending amount of the carbon black exceeds 40 parts by mass and 110 parts by mass or less with respect to 100 parts by mass of the rubber component. Stuff.
2. The rubber composition for anti-vibration rubber according to 1 above, wherein the polystyrene-equivalent number average molecular weight (Mn) of the liquid styrene-butadiene rubber (II) is 5,000 or less.
3. The rubber composition for anti-vibration rubber according to 1 or 2 above, wherein the blending amount of the liquid styrene-butadiene rubber (II) is 35 parts by mass or more with respect to 100 parts by mass of the styrene-butadiene rubber (I).
4. The rubber composition for anti-vibration rubber according to any one of 1 to 3 above, wherein the carbon black has a nitrogen adsorption specific surface area of 90 to 150 m ² / g according to JIS K 6217-2: 2001.
5. 5. The rubber composition for a vibration proof rubber according to any one of 1 to 4 above, wherein the carbon black is SAF grade or ISAF grade.
6. A vibration-proof rubber product containing a vibration-proof rubber member comprising the rubber composition for vibration-proof rubber according to any one of 1 to 5 above as a constituent element.

According to the rubber composition for anti-vibration rubber of the present invention, high durability can be realized not only in the low loss region but also in the high loss region, and a good low dynamic ratio can be obtained.

Hereinafter, the present invention will be described in more detail.
The rubber component of the rubber composition for anti-vibration rubber of the present invention includes styrene-butadiene rubber (I) having a polystyrene-equivalent weight average molecular weight (Mw) of 700,000 or more. In the present invention, the "rubber component" refers to a rubber component having a polystyrene-equivalent weight average molecular weight (Mw) of 100,000 or more, and does not include liquid styrene-butadiene rubber. Unless otherwise specified, it means a solid state at 23°C.

The above-mentioned styrene-butadiene rubber (I) can be a matrix of vibration-proof rubber. The polystyrene-equivalent weight average molecular weight (Mw) of the styrene-butadiene rubber (I) is 700,000 or more, preferably 800,000 or more, more preferably 850,000 or more, and the upper limit is not particularly limited. However, it is preferably 1,500,000 or less. If the average molecular weight is 700,000 or more, the entanglement of the molecules with the liquid styrene-butadiene rubber (II) described below occurs, and the durability such as crack growth resistance is increased. The above polystyrene-equivalent weight average molecular weight (Mw) means the polystyrene-equivalent weight average molecular weight obtained by gel permeation chromatography (GPC), and is the polystyrene-equivalent of the liquid styrene butadiene rubber (II) described later. The same applies to the weight average molecular weight (Mw).

The styrene-butadiene rubber (I) is generally composed of a copolymerization of styrene and 1,3-butadiene, and can be prepared by solution polymerization or emulsion polymerization.

The component ratio of "styrene / vinyl" (St / Vi) of the styrene-butadiene rubber (I) is a mass ratio, preferably 20 to 50/15 to 50, and more preferably 24 to 46/16 to 46. In the above "styrene / vinyl" or "St / Vi", "styrene (St)" means the styrene content in the target styrene-butadiene rubber, and "vinyl (Vi)" is the target. It means the vinyl bond content in the styrene-butadiene rubber, that is, the mass of butadiene incorporated at positions 1 and 2 in the polymer chain of the styrene-butadiene rubber. Strictly speaking, the component ratio of the above "styrene / vinyl" (St / Vi) is "styrene (mass%) / vinyl (mass%)" or "St (mass%) / Vi (mass%)". .. The same applies to the following description.

The glass transition temperature (Tg) of the styrene-butadiene rubber (I) is preferably −60 to −20 ° C., more preferably −55 to −20 ° C. The glass transition temperature (Tg) of the styrene-butadiene rubber (I) is preferably lower than the glass transition temperature (Tg) of the styrene-butadiene rubber (II) described later.

The rubber composition of the present invention contains liquid styrene-butadiene rubber (II) having a polystyrene-equivalent weight average molecular weight (Mw) of 12,000 or less. The liquid styrene-butadiene rubber (II) is dispersed in the matrix phase of the vibration-proof rubber. The polystyrene reduced weight average molecular weight (Mw) of the liquid styrene-butadiene rubber (II) is preferably 11,000 or less, more preferably 10,000 or less, and the lower limit is not particularly limited, but preferably 5, 000 or more, more preferably 7,000 or more, further preferably 8,000 or more, and most preferably 9,000 or more. When the average molecular weight is 12,000 or less, the entanglement of molecules with the styrene-butadiene rubber (I) causes the vibration-proof rubber composition to have durability such as crack resistance. Growth is improved.

The polystyrene equivalent number average molecular weight (Mn) of the liquid styrene-butadiene rubber (II) is preferably 5,000 or less, more preferably 4,500 or less, and the lower limit is preferably 1,000 or more. is there.

The liquid styrene-butadiene rubber (II) can be prepared by solution polymerization or emulsion polymerization.

The content ratio of “styrene/vinyl” (St/Vi) of the liquid styrene-butadiene rubber (II) is preferably 20 to 30/20 to 75, more preferably 25 to 30/50 to 70 in terms of mass ratio.

The glass transition temperature (Tg) of the liquid styrene-butadiene rubber (II) is preferably −70 to −10° C., more preferably −30 to −15° C. The glass transition temperature (Tg) of the styrene-butadiene rubber (II) is preferably higher than the glass transition temperature (Tg) of the styrene-butadiene rubber (I). The difference between the Tg of the liquid styrene-butadiene rubber ((II)) and the Tg of the styrene-butadiene rubber (I) is preferably 30 ° C. or less, more preferably 25 ° C. or less, still more preferably 22 ° C. or less, still more preferably 18. It is within ℃, most preferably within 15 ℃.

Regarding the total amount of vinyl bond content in the component (I) and the component (II), the components (I) and (II) are entangled with each other and the durability is improved. ) With respect to 100% by mass of the total components, it is 25% by mass or more, preferably 27% by mass or more, and more preferably 30% by mass or more.

Further, the compounding amount of the liquid styrene-butadiene rubber (II) is preferably 20 parts by mass or more, and more preferably 25 parts by mass or more with respect to 100 parts by mass of the rubber component.

Further, the mixing ratio of the component (I) and the component (II) is preferably (I)/(II) (mass ratio) of 100/40 to 100/30, and more preferably 100/40. 40 to 100/35.

A rubber component other than the above components (I) and (II) can be blended, and for example, a diene rubber may be contained. As the diene rubber, known rubbers can be used and are not particularly limited, but for example, natural rubber (NR); butadiene rubber (BR), isoprene rubber, styrene-isoprene copolymer, and chloroprene rubber. , Acrylonitrile-butadiene rubber, acrylate butadiene rubber, and other diene-based synthetic rubbers; natural rubber such as epoxidized natural rubber, and diene-based synthetic rubbers with modified molecular chain terminals.

The anti-vibration rubber composition of the present invention preferably contains one type of the above-mentioned diene rubber (III) alone or two or more types. Among the above-mentioned diene rubber (III), it is preferable to contain at least one selected from the group consisting of natural rubber, butadiene rubber, and styrene-butadiene rubber, and it is more preferable to contain at least natural rubber. For example, the anti-vibration rubber composition of the present invention may contain, as the diene rubber (III), natural rubber alone, or may contain natural rubber and butadiene rubber.

When the rubber composition of the present invention contains the diene-based rubber (III) such as natural rubber, the blending ratio (I) / (III) of the component (I) and the diene-based rubber (III) is For example, in the case of SBR/NR, the mass ratio is preferably 100/0 to 50/50, more preferably 90/10 to 60/40, and further preferably 90/10 to 70/30.

The anti-vibration rubber composition of the present invention may contain a rubber (other rubber) other than the diene rubber (III), but from the viewpoint of not impairing the effect of the present invention, the styrene butadiene rubber (I) and the diene rubber are used. The content of the styrene-butadiene rubber (I) and the diene rubber in the total rubber of the rubber (III) and the other rubber is preferably 80% by mass or more, and 90% by mass based on the total mass of the rubber. The above content is more preferable, the content is more preferably 95% by mass or more, and particularly preferably 100% by mass.

Examples of other rubbers include acrylic rubber, ethylene-propylene rubber (EPR, EPDM), fluororubber, silicone rubber, urethane rubber, butyl rubber, etc. Only one of these rubbers may be used, or two or more of them may be used. Can be used together. The content of the other rubber in the total rubber is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total mass of the rubber, from the viewpoint of not impairing the effects of the present invention. It is more preferably 5% by mass or less, and particularly preferably 0% by mass.

Carbon black can be added to the rubber composition of the present invention as a filler. As the carbon black, known ones can be used. Also, the nitrogen adsorption specific surface area of the carbon black, JIS K 6217-2: conforms to 2001, preferably has a nitrogen adsorption specific surface area of 90 ~ 150m ² / g, more preferably 110 ~ 150m ² / g, more preferably 130-150 m ² / g.

Examples of the carbon black include carbon blacks of SRF class, GPF class, FEF class, HAF class, ISAF class, SAF class, FT class, MT class and the like, and in particular, high loss property and durability. SAF grade or ISAF grade can be preferably used from the viewpoint of compatibility with both.

Also, these carbon blacks may be used alone or in combination of two or more. The blending amount of these carbon blacks is appropriately selected according to the type of carbon black to be used, but from the viewpoint of achieving both high loss property and durability and maintaining a low dynamic ratio, 100 parts by mass of the rubber component is added. On the other hand, it is more than 40 parts by mass, preferably 45 parts by mass or more, and more preferably 50 parts by mass or more. The upper limit is 110 parts by mass or less, preferably 100 parts by mass or less.

Sulfur can be added to the rubber composition of the present invention. The total amount of sulfur blended is preferably 0.1 to 5 parts by mass, preferably 0.3 to 3.0 parts by mass with respect to 100 parts by mass of the rubber component.

A vulcanization accelerator may be added to the rubber composition of the present invention. Examples of the vulcanization accelerator include 2-mercaptobenzothiazole, dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazyl sulfenamide, Nt-butyl-2-benzothiazyl sulfenamide, N- Benzothiazole-based vulcanization accelerators such as t-butyl-2-benzothiazylsulfenamide; guanidine-based vulcanization accelerators such as diphenylguanidine; tetramethylthiuram disulfide, tetrabutylthiuram disulfide, tetradodecylthiuram disulfide, tetra Examples thereof include thiuram vulcanization accelerators such as octyl thiuram disulfide and tetrabenzyl thiuram disulfide; dithiocarbamate salts such as zinc dimethyldithiocarbamate; and zinc dialkyldithiophosphate.

As for the above vulcanization accelerator, one kind such as sulfenamide type, thiuram type, thiazole type, guanidine type, dithiocarbamate type may be used alone, or two or more kinds may be used in combination. .. To adjust the vulcanization behavior (rate), thiuram and / or thiazole with a relatively high vulcanization promoting capacity, and guanidine and / or sulfenamide with a relatively medium to low vulcanization promoting capacity. The combination with the vulcanization accelerator of is preferably adopted. Specifically, a combination of tetramethylthiuram disulfide and N-cyclohexyl-2-benzothiadylsulfenamide, a combination of tetrabutylthiuram disulfide and Nt-butyl-2-benzothiadylsulfenamide, dibenzo Examples include a combination of thiazyl disulfide and diphenylguanidine. The compounding amount of the vulcanization accelerator is preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the rubber component.

In the present invention, auxiliary agents such as zinc oxide (ZnO) and fatty acids can be blended. The fatty acid may be saturated, unsaturated, straight-chain, or branched fatty acid, and the carbon number of the fatty acid is not particularly limited, but may be, for example, 1 to 30 carbon atoms, preferably 15 to 30 fatty acids, more specifically cyclohexanoic acid (cyclohexanecarboxylic acid), naphthenic acid such as alkylcyclopentane having a side chain, hexanoic acid, octanoic acid, decanoic acid (including branched carboxylic acid such as neodecanoic acid), Saturated fatty acids such as dodecanoic acid, tetradecanoic acid, hexadecanoic acid and octadecanoic acid (stearic acid), unsaturated fatty acids such as methacrylic acid, oleic acid, linoleic acid and linolenic acid, resin acids such as rosin, tall oil acid and abietic acid Is mentioned. These may be used alone or in combination of two or more. In the present invention, zinc oxide and stearic acid can be preferably used. The amount of these auxiliaries compounded is preferably 1 to 10 parts by mass, more preferably 2 to 7 parts by mass, relative to 100 parts by mass of the rubber component. If the amount is more than 10 parts by mass, workability may be deteriorated and the dynamic ratio may be deteriorated. If it is less than 1 part by mass, vulcanization may be delayed.

Well-known oils can be used and are not particularly limited, but specifically, process oils such as aromatic oil, naphthene oil, paraffin oil, vegetable oils such as coconut oil, synthetic oils such as alkylbenzene oil, and castor oil. Oil etc. can be used. In the present invention, naphthene oil can be preferably used. These may be used alone or in combination of two or more. The blending amount of oil is not particularly limited, but from the viewpoint of kneading workability, it is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, and further preferably 10 parts by mass with respect to 100 parts by mass of the rubber component. Parts or more, more preferably 15 parts by mass or more, most preferably 20 parts by mass or more, and the lower limit is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, further preferably 35 parts by mass or less. is there. When the oil-extended rubber is used as the rubber component, the total amount of the oil contained in the rubber and the oil added separately during the mixing may be within the above range.

Examples of the resin include phenol resin, rosin resin, DCPD resin, C5 petroleum resin, C9 petroleum resin, alicyclic petroleum resin, resin obtained by copolymerizing C5 petroleum resin and C9 petroleum resin, xylene resin, and terpen. Examples include at least one resin selected from the group consisting of resins, ketone resins, polyester polyol resins, and modified resins of these resins. These resins can be blended in a range of less than 10 parts by mass with respect to 100 parts by mass of the rubber component, and preferably 0 parts by mass with respect to 100 parts by mass of the rubber component. That is, it is preferable that the rubber composition does not need to include the resin.

As the antiaging agent, known ones can be used and are not particularly limited, and examples thereof include a phenol antiaging agent, an imidazole antiaging agent, and an amine antiaging agent. The antiaging agent may be used alone or in combination of two or more kinds. The blending amount of the antiaging agent is preferably 0.1 to 10 parts by mass, and more preferably 0.3 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

In addition, waxes, antioxidants (aging inhibitors), fillers, foaming agents, plasticizers that are usually used in the rubber industry are added to the above rubber components, if necessary, within a range that does not impair the effects of the present invention. Additives such as agents, oils, lubricants, tackifiers, petroleum-based resins, ultraviolet absorbers, dispersants, compatibilizers, homogenizers, and vulcanization retarders can be appropriately added.

When obtaining the rubber composition of the present invention, there is no particular limitation on the mixing method of the above-mentioned respective components, and all raw materials of the components may be mixed at once and kneaded, or each component may be divided into two stages or three stages. You may mix and knead. For kneading, a kneading machine such as a roll, an internal mixer, a Banbury rotor or the like can be used. Further, when forming into a sheet shape or a belt shape, a known molding machine such as an extrusion molding machine or a press machine may be used.

The vulcanization conditions for curing the rubber composition are not particularly limited, but vulcanization conditions of usually 140 to 180° C. for 5 to 120 minutes can be adopted.

The anti-vibration rubber product of the present invention includes an anti-vibration rubber member made of a rubber composition for anti-vibration rubber as a constituent element. The anti-vibration rubber product is usually a component in which a rubber material and another member such as metal or resin are brought into contact with each other, and the unvulcanized rubber composition and the above-mentioned separate member are bonded to each other by using an adhesive, if necessary. By heating and pressurizing, the rubber composition can be vulcanized, and at the same time, a vibration-proof rubber product can be obtained in which the vulcanized rubber and the separate member are bonded and integrated. Anti-vibration rubber products may have various adhesives interposed between the vulcanized rubber and the metal, or between the vulcanized rubber and the resin, or directly integrated by fitting without using the adhesive. Can be made.

Examples of anti-vibration rubber products include anti-vibration rubber products for vehicles, anti-vibration rubber products for railroads, air springs, air sleeves and anti-vibration rubber products for automobiles. Of these, as vibration-proof rubber products for automobiles, specifically, torsional dampers, engine mounts, torque rods, liquid seal mounts, upper mounts, strut mounts, bumper stoppers, muffler hangers, inner and outer cylinder bushes, suspension bushes, dampers, etc. It is suitably applied to couplings, center supports, cabin mounts, member mounts, toe collect bushes, stabilizer bushes, and the like.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 and 3]
The compounding composition shown in Table 1 was kneaded, and the rubber compositions for anti-vibration rubber of each of Examples 1 and 3 were vulcanized and cured into a predetermined shape under predetermined conditions to prepare a molded product. The obtained molded product was used as an evaluation body for the anti-vibration rubber of the present invention. The obtained molded product was evaluated for durability, high loss property and dynamic magnification (Kd/Ks) according to the following contents. The results are shown in Table 2.

[Example 2, Comparative Examples 1 to 4]
The compounding composition shown in Table 1 is kneaded, and the rubber compositions for anti-vibration rubber of Examples 2 and Comparative Examples 1 to 4 are vulcanized and cured into a predetermined shape under predetermined conditions to prepare a molded product. The obtained molded product is used as an evaluation body of the anti-vibration rubber of the present invention. The durability, high loss property, and dynamic magnification (Kd/Ks) of the obtained molded product are predicted and evaluated by the following contents. The results are shown in Table 2.

[Moving ratio (Kd/Ks)]
A rubber composition as a sample is press-molded (vulcanized) to produce a cylindrical test piece (diameter 8 mm, height 6 mm), and a dynamic viscoelasticity tester (trade name "Eplexor 500N" is used for this test piece. , GABO) at a test temperature of 35° C. according to the following method in accordance with JIS K 6385:2012: static spring constant (Ks), dynamic spring constant (Kd) measured at 100 Hz, and dynamic magnification (Kd). /Ks) was measured. The kinetic magnification (Kd/Ks) obtained in Comparative Example 1 was set as 100 and displayed as an index. The lower the number of this index, the better the low dynamic magnification.

[High loss property (tan δ/hysteresis loss)]
The dynamic viscoelasticity tester was used for measurement in accordance with JIS K 6385:2012. The tan δ obtained in Comparative Example 1 was set as 100, and the result was displayed as an index. The higher the number of this index, the better the high loss property.

[Durability (extension fatigue durability)]
For the samples obtained in each Example and Comparative Example, dumbbell-shaped test pieces were prepared, repeatedly fatigued at 35 ° C. with a constant strain of 100 to 300%, and the number of repetitions until the test pieces broke was measured. An energy-breakage number conversion formula was calculated from the input energy given to the test piece at each test strain and the number of breaks at each test strain. Using this conversion formula, the value converted for the number of breaks when the input energy was 1 MPa was used as the crack growth resistance, and the samples of each Example and Comparative Example were obtained. The fracture count conversion value obtained in Comparative Example 1 was set as 100 and displayed as an index. The higher the number in this index, the better the extensional fatigue resistance.

Details of the rubber compound in Table 2 are as follows.

Natural rubber (NR)
Natural rubber (NR): "RSS#3"

Styrene butadiene rubber (SBR)
The styrene-butadiene rubber used in each example is shown in the table below.

The above No. 1 to No. The product names of 4 are as follows.
"No. 1""No.2": emulsion polymerization SBR made by JSR
"No. 3": "#0202" made by JSR
"No. 4": "Ricon (registered trademark) 100" manufactured by CRAY VALLEY

Carbon black ISAF grade carbon black: product name "#80" manufactured by Asahi Carbon Co., Ltd. (average particle size: 22 nm, nitrogen absorption specific surface area: 115 m ² /g, DBP oil supply amount (method A): 113 ml/100 g)

Zinc Hua Mitsui Mining & Smelting Co., Ltd., zinc oxide type II
Anti-aging agent: RD
2,2,4-Trimethyl-1,2-dihydroquinoline polymer, "Nocrac 224" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Anti-aging agent: 6C
N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, "Ozonone 6C" manufactured by Seiko Kagaku Co., Ltd.
Resin Sumitomo Bakelite Co., Ltd., "SUMILITERESIN 217"
Oil process oil, "Diana Process NH-70S" manufactured by Idemitsu Kosan Co., Ltd.
Sulfur oil Sulfur: "HK200-5" manufactured by Hosoi Chemical Industry Co., Ltd.
Vulcanization accelerator: CZ
N-cyclohexyl-2-benzothiazolylsulfenamide, "NOXCELLER CZ-G" manufactured by Ouchi Shinko Chemical Co., Ltd.
Vulcanization accelerator: DM
Di-2-benzothiazolyl disulfide, "Noxeller DM-P" manufactured by Ouchi Shinko Kagaku Co., Ltd.

From the results in Table 2 above, Examples 1 to 3 have lower dynamic ratios and durability than Comparative Examples 1 and 2 using styrene-butadiene rubber (I) having a polystyrene-equivalent weight average molecular weight of less than 700,000. Are better.
Further, Examples 1 to 3 are superior in low dynamic magnification and durability as compared with Comparative Example 3 using a resin.
Further, Examples 1 to 3 are superior in durability in a high loss region as compared with Comparative Example 4 in which liquid SBR is not blended. Comparative Example 4 has a small rubber loss (tan δ).

Claims (6)

1. Liquid styrene-butadiene rubber (II) containing at least styrene-butadiene rubber (I) having a polystyrene-equivalent weight average molecular weight (Mw) of 700,000 or more as a rubber component and having a polystyrene-equivalent weight average molecular weight (Mw) of 12,000 or less. ) And carbon black as a filler, wherein the total vinyl bond content in the component (I) and the component (II) is the same as the component (I) and the component (II). 25% by mass or more with respect to 100% by mass in total, and the amount of the carbon black compounded is more than 40 parts by mass and 110 parts by mass or less with respect to 100 parts by mass of the rubber component. A rubber composition for rubber.
2. The rubber composition for anti-vibration rubber according to claim 1, wherein the polystyrene-equivalent number average molecular weight (Mn) of the liquid styrene-butadiene rubber (II) is 5,000 or less.
3. The rubber composition for a vibration isolating rubber according to claim 1 or 2, wherein the compounding amount of the liquid styrene-butadiene rubber (II) is 35 parts by mass or more based on 100 parts by mass of the styrene-butadiene rubber (I).
4. The rubber composition for anti-vibration rubber according to any one of claims 1 to 3, wherein the carbon black has a nitrogen adsorption specific surface area of 90 to 150 m ² / g according to JIS K 6217-2: 2001.
5. The rubber composition for anti-vibration rubber according to any one of claims 1 to 4, wherein the carbon black is SAF grade or ISAF grade.
6. A vibration-proof rubber product containing a vibration-proof rubber member comprising the rubber composition for vibration-proof rubber according to any one of claims 1 to 5 as a component.