JP2020090664A - Rubber composition for anti-vibration rubber and anti-vibration rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a vibration damping rubber, which is a raw material of a highly damped vibration damping rubber, and a vibration damping rubber.
SOLUTION: When a total amount of a rubber component is 100 parts by mass, an anti-static agent containing 85 to 100 parts by mass of a solution-polymerized styrene-butadiene rubber having a styrene content of 10 to 45% by mass and a vinyl content of 30 to 65% by mass. Rubber composition for vibrating rubber. The solution-polymerized styrene-butadiene rubber is preferably a modified solution-polymerized styrene-butadiene rubber, and when the total amount of the rubber component is 100 parts by mass, the solution-polymerized styrene-butadiene rubber preferably contains 90 to 100 parts by mass. When the total amount of the above is 100 parts by mass, it is preferable to contain 30 to 100 parts by mass of carbon black.
[Selection diagram] None

Description

The present invention relates to a rubber composition for vibration isolating rubber, and more particularly to a rubber composition for vibration isolating rubber and a vibration isolating rubber that can be suitably used as a vibration isolating member such as an engine mount for automobiles.

Anti-vibration rubber is used in vehicles such as automobiles to absorb vibrations of the engine and vehicle body. Therefore, such a vibration-proof rubber is required to have high damping properties.

In Patent Document 1 below, a specific amount of sulfur and a specific carbon black are blended with 100 parts by mass of a rubber component containing 50 to 90 parts by mass of natural rubber and 50 to 10 parts by mass of styrene-butadiene rubber as main components. The technology is described.

In Patent Document 2 below, a specific amount of sulfur and a specific carbon black are added to 100 parts by mass of a rubber component containing 50 to 85 parts by mass of natural rubber and 50 to 15 parts by mass of a terminal-modified styrene-butadiene rubber as main components. Blending techniques are described.

In Patent Document 3 below, in order to reduce rolling resistance of a pneumatic tire, a specific amount of sulfur and a vulcanization accelerator are added to 100 parts by mass of a diene rubber component containing 40 parts by mass or more of styrene-butadiene rubber, and A technique for producing a tread member using a rubber composition containing a specific carbon black as a raw material is described.

JP 2001-240702 A JP, 2000-336206, A JP, 2007-9160, A

As a result of diligent studies by the present inventors regarding the above-mentioned conventional technique, it has been found that the techniques described in Patent Documents 1 and 2 above have room for further improvement regarding the high damping of the vibration-proof rubber. The technique described in Patent Document 3 was developed for the purpose of reducing the rolling resistance of the pneumatic tire, and there is no description or suggestion regarding high damping, which is a problem peculiar to the vibration-proof rubber.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a rubber composition for a vibration damping rubber, which is a raw material of a highly damped vibration damping rubber, and a vibration damping rubber.

The above problems can be solved by the following configurations. That is, the rubber composition for anti-vibration rubber according to the present invention has a styrene content of 10 to 45 mass% and a vinyl content of 30 to 65 mass% when the total amount of the rubber components is 100 parts by mass. It is characterized by containing 85 to 100 parts by mass of rubber. Generally, styrene-butadiene rubber is roughly classified into solution-polymerized styrene-butadiene rubber (hereinafter, also referred to as “S-SBR”) and emulsion-polymerized styrene-butadiene rubber (hereinafter, also referred to as “E-SBR”). In comparison, S-SBR has a narrow molecular weight distribution (Mw/Mn). Since the rubber composition for a vibration-proof rubber according to the present invention contains a large amount of S-SBR whose styrene content and vinyl content are optimally designed, the vibration-proof rubber produced using this as a raw material exhibits high damping properties. ..

In the rubber composition for vibration-proof rubber, the solution-polymerized styrene-butadiene rubber is preferably a modified solution-polymerized styrene-butadiene rubber. As described above, since S-SBR has a narrow molecular weight distribution (Mw/Mn), when the filler is contained in the rubber composition for vibration damping rubber, the effect of modifying the rubber is sufficiently exerted, and the filler is dispersed. Greatly contributes to the improvement of the property. As a result, the anti-vibration rubber produced using this as a raw material exhibits higher damping properties.

In the above rubber composition for anti-vibration rubber, it is preferable to contain 90 to 100 parts by mass of the solution-polymerized styrene-butadiene rubber when the total amount of the rubber component is 100 parts by mass. According to such a configuration, the content of the solution-polymerized styrene-butadiene rubber in the rubber composition for vibration damping rubber is further increased, so that not only the damping of the finally manufactured vibration damping rubber is increased but also the dynamic ratio is increased. It is possible to achieve compatibility with reduction of (dynamic spring constant/static spring constant). The dynamic ratio is an index of vehicle interior noise, and the lower the better, the better.

In the above rubber composition for anti-vibration rubber, when the total amount of the rubber component is 100 parts by mass and the content of carbon black is 30 to 100 parts by mass, the hardness (static spring constant) of the vulcanized rubber is equivalent to that of the anti-vibration rubber. It is preferable because it becomes suitable.

The anti-vibration rubber according to the present invention is obtained by vulcanizing and molding the rubber composition for anti-vibration rubber described above.

The rubber composition for anti-vibration rubber according to the present invention contains 85% S-SBR having a styrene content of 10 to 45 mass% and a vinyl content of 30 to 65 mass% when the total amount of the rubber component is 100 parts by mass. ~ 100 parts by mass.

S-SBR is generally obtained by anionic polymerization of a raw material monomer in a hydrocarbon, and has both a molecular weight distribution and a vinyl amount compared with E-SBR obtained by an emulsion polymerization method (suspension polymerization method) in water. The feature is that it can be controlled. The method for producing S-SBR is not particularly limited as long as S-SBR having a styrene content of 10 to 45% by mass and a vinyl content of 30 to 65% by mass can be produced by a method known to those skilled in the art. Applicable. In order to improve the damping property of the finally obtained vibration-proof rubber, the amount of styrene in S-SBR is preferably 20 to 45% by mass. Similarly, the content of vinyl in S-SBR is preferably 50 to 65 mass %.

In the present invention, it is preferable to use modified S-SBR as S-SBR. The modified S-SBR contains a functional group containing a heteroatom. The functional group containing a hetero atom may be introduced at the end of the polymer chain or may be introduced in the polymer chain, but is preferably introduced at the end. Examples of the functional group containing a hetero atom include an amino group, an alkoxyl group, a hydroxyl group, an epoxy group, a carboxyl group, a cyano group and a halogen group. The modified solution polymerized SBR can contain at least one of the exemplified functional groups. Examples of the amino group include a primary amino group, a secondary amino group and a tertiary amino group. Examples of the alkoxyl group include a methoxy group, an ethoxy group, a propoxy group and a butoxy group. Examples of the halogen group include chlorine and bromine. The exemplified functional groups interact with various functional groups contained in the filler, particularly carbon black, and silanol groups (Si—OH) of silica. Here, the interaction means, for example, in the case of silica, a chemical bond or a hydrogen bond by a chemical reaction with a silanol group of silica. Note that S-SBR may be an oil-extended product such as carbon black or silica for the purpose of improving the filling property and processability.

The rubber composition for a vibration-proof rubber according to the present invention contains 85 to 100 parts by mass of S-SBR when the total amount of the rubber component is 100 parts by mass. However, in order to achieve both high damping and low dynamic magnification of the anti-vibration rubber, 90 to 100 parts by mass of S-SBR is preferably contained when the total amount of the rubber component is 100 parts by mass, and 95 To 100 parts by mass are more preferable, and it is particularly preferable that S-SBR is contained in 100 parts by mass.

In the rubber composition for vibration-proof rubber according to the present invention, examples of the rubber component which may be compounded in addition to S-SBR include natural rubber (NR). Other than natural rubber, for example, diene-based synthetic rubber such as isoprene rubber (IR), butadiene rubber (BR), butyl rubber (IIR), and acrylonitrile butadiene rubber (NBR); brominated butyl rubber (BR-IIR) and the like. Halogenated butyl rubber; other synthetic rubbers such as polyurethane rubber, acrylic rubber, fluororubber, silicone rubber, and chlorosulfonated polyethylene may be contained.

The rubber composition for vibration-proof rubber according to the present invention preferably contains carbon black. Examples of carbon black include SAF class (N100 series in ASTM number), ISAF class (N200 series in the same series), HAF class (300 series in the same series), FEF class (N500 series in the same series), GPF class (N600 series in the same series), SRF class. Carbon black used in the usual rubber industry, such as the same 700 series, can be used. The carbon black may be a granulated carbon black or a non-granulated carbon black granulated in consideration of its handling property in a usual rubber industry. From the viewpoint of optimizing the hardness (static spring constant) of the anti-vibration rubber, when the total amount of the rubber component is 100 parts by mass, the content of carbon black is preferably 30 to 100 parts by mass, and 30 to 60 parts by mass. It is more preferable to set it as a mass part.

The rubber composition for anti-vibration rubber of the present invention, together with the rubber component and carbon black, a sulfur-based vulcanizing agent, a vulcanization accelerator, silica, a silane coupling agent, stearic acid, a vulcanization accelerating aid, and a vulcanization delay. Compounding agents that are usually used in the rubber industry, such as agents, antiaging agents, softening agents such as wax and oil, and processing aids, can be appropriately blended and used within a range that does not impair the effects of the present invention.

The rubber composition for a vibration-proof rubber according to the present invention preferably contains a sulfur-based vulcanizing agent. Sulfur as the sulfur-based vulcanizing agent may be ordinary sulfur for rubber, and for example, powdered sulfur, precipitated sulfur, insoluble sulfur, highly dispersible sulfur and the like can be used. The content of sulfur in the rubber composition for a vibration isolating rubber according to the present invention is 0.15 to 3 parts by mass with respect to 100 parts by mass of the rubber component when considering the dynamic ratio of the antivibration rubber produced. Is preferable, and it is more preferable that it is 0.7 to 3 parts by mass.

As the vulcanization accelerator, usually used for rubber vulcanization, sulfenamide vulcanization accelerator, thiuram vulcanization accelerator, thiazole vulcanization accelerator, thiourea vulcanization accelerator, guanidine vulcanization A vulcanization accelerator such as an accelerator or a dithiocarbamate vulcanization accelerator may be used alone or in an appropriate mixture. The compounding amount of the vulcanization accelerator is preferably 1 to 5 parts by mass, and more preferably 1 to 3 parts by mass with respect to 100 parts by mass of the rubber component.

As the anti-aging agent, usually used for rubber, aromatic amine anti-aging agent, amine-ketone anti-aging agent, monophenol anti-aging agent, bisphenol anti-aging agent, polyphenol anti-aging agent, dithiocarbamic acid Antiaging agents such as salt antiaging agents and thiourea antiaging agents may be used alone or in admixture.

The rubber composition for anti-vibration rubber of the present invention, together with the rubber component and carbon black, a sulfur-based vulcanizing agent, a vulcanization accelerator, silica, a silane coupling agent, stearic acid, a vulcanization accelerating aid, and a vulcanization delay. Agents, antioxidants, softeners such as wax and oil, processing aids and other compounding agents normally used in the rubber industry, and kneading machines used in the usual rubber industry such as Banbury mixers, kneaders and rolls. It can be obtained by kneading.

Further, the mixing method of each of the above components is not particularly limited, and a sulfur-based vulcanizing agent, and a compounding component other than the vulcanizing system component such as a vulcanization accelerator are kneaded in advance to form a masterbatch, and the remaining components are added. And further kneading, a method of adding each component in an arbitrary order and kneading, a method of simultaneously adding all components and kneading, and the like.

By high-damping the anti-vibration rubber, it is possible to knead each of the above-mentioned components, perform molding, and then perform vulcanization. The vulcanization temperature may be, for example, 120 to 200°C, preferably 140 to 180°C.

Specific examples of the anti-vibration rubber application according to the present embodiment include engine mounts, strut mounts, body mounts, cab mounts, member mounts, differential mounts, and other mounts, suspension bushes, arm bushes, torque bushes, and other bushes, and torsional dampers. , Various muffler hangers, damper pulleys, dynamic dampers, and other anti-vibration rubber for automobiles. Further, in addition to automobiles, it can be suitably used for anti-vibration rubber for railway vehicles, anti-vibration rubber for industrial machines, anti-vibration rubber for construction, anti-vibration rubber for anti-vibration rubber, etc.

Hereinafter, the embodiments of the present invention will be described in more detail.

(Preparation of rubber composition)
The rubber compositions of Examples 1 to 6 and Comparative Example 1 were compounded with 100 parts by mass of the rubber component according to the compounding recipe of Table 1, and kneaded with a usual Banbury mixer to prepare a rubber composition. Each compounding agent shown in Table 1 is shown below.

・Solution-polymerized styrene-butadiene rubber (S-SBR)
S-SBR1: "Nipol NS612" manufactured by Zeon Corporation (styrene content 15% by mass, vinyl content 30% by mass, modified S-SBR)
S-SBR2: "SL563" manufactured by JSR (styrene content 20 mass %, vinyl content 55.5 mass %, modified S-SBR).
S-SBR3: "Toughden E580" manufactured by Asahi Kasei (styrene content 35.5 mass %, vinyl content 43 mass %, modified S-SBR, 37.5 mass parts oil extended product)
・Carbon black GPF (N660): "Seast V" manufactured by Tokai Carbon Co., Ltd.
・Zinc oxide: "3 types of zinc oxide" manufactured by Sakai Chemical Industry Co., Ltd.
・Stearic acid: "Lunack S20" manufactured by Kao Corporation
・Oil: "NC140" manufactured by JX Nippon Oil & Energy Corporation
・Anti-aging agent 1: "6C" made by Ouchi Shinko Chemical Co., Ltd.
・Anti-aging agent 2: "RD" manufactured by LANXESS
* Wax: "Ozo Ace 2701" manufactured by Nippon Seiro Co., Ltd.
・Sulfur: "5% oil-containing fine powder sulfur" manufactured by Tsurumi Chemical Industry Co., Ltd.
・Vulcanization accelerator 1: "CZ" manufactured by Ouchi Shinko Chemical Co., Ltd.
・Vulcanization accelerator 2: "TS" manufactured by Ouchi Shinko Chemical Co., Ltd.

Examples 1 to 6 and Comparative Example 1
Using a Banbury mixer, according to the composition (parts by mass) shown in Table 1 below, first, in the first mixing step, the components other than sulfur, the vulcanization accelerator and the vulcanization retarder were added and mixed (the discharge temperature at the time of mixing). 120° C.), and then, sulfur and a vulcanization accelerator were added and mixed to the obtained mixture in the final mixing stage to prepare a rubber composition for a vibration-proof rubber. For each rubber composition, a vulcanized rubber was prepared and its properties were evaluated.

The obtained vulcanized rubber was evaluated according to the following evaluation criteria.

[Attenuation]
For a vulcanized rubber sample having a cylindrical shape (diameter 50 mm, height 25 mm) obtained by vulcanizing each rubber composition at 170° C. for 12 minutes using a predetermined mold, frequency 15 Hz, amplitude ±2% And tan δ was measured. The evaluation was performed by indexing the result of Comparative Example 1 as 100. The larger the index, the higher the damping property of the vulcanized rubber and the better.

[Moving ratio]
(Static spring constant (Ks))
Each rubber composition was press-molded while being vulcanized at 170° C. for 12 minutes to prepare a vulcanized rubber sample having a columnar shape (diameter 50 mm, height 25 mm). After compressing the produced test piece twice in the axial direction of the cylinder for 5 mm, the deflection loads of 1.25 mm and 3.75 mm were measured from the deflection curves when the strain was restored, and the static spring was calculated from these values. A constant (Ks) (N/mm) was calculated.
(Dynamic spring constant (Kd))
The test piece used to measure the static spring constant (Ks) was compressed by 2.5 mm in the axial direction of the cylinder, and centered on this compressed position of 2.5 mm, a constant amplitude of 0.05 mm was applied at a frequency of 100 Hz from below. Displacement harmonic compression vibration was applied, the dynamic load was detected by the upper load cell, and the dynamic spring constant (Kd) (N/mm) was calculated according to JIS-K 6394.
(Moving ratio: Kd/Ks)
The dynamic magnification was calculated by the following formula.
(Dynamic magnification)=(Dynamic spring constant (Kd))/(Static spring constant (Ks))
The results are shown in Table 1.

The results are shown in Table 1, and it can be seen that the damping properties of the vulcanized rubbers are higher in Examples 1 to 6 than in Comparative Example 1 which is the control. In particular, in Examples 1, 3 and 5 which contain 90 parts by mass or more of S-SBR, it is understood that the high damping and the low dynamic magnification of the anti-vibration rubber are compatible at a high level.

Claims (5)

When the total amount of the rubber component is 100 parts by mass, 85 to 100 parts by mass of a solution-polymerized styrene-butadiene rubber having a styrene content of 10 to 45% by mass and a vinyl content of 30 to 65% by mass is contained. Rubber composition for anti-vibration rubber. The rubber composition for a vibration damping rubber according to claim 1, wherein the solution-polymerized styrene-butadiene rubber is a modified solution-polymerized styrene-butadiene rubber. The rubber composition for a vibration isolating rubber according to claim 1 or 2, which contains 90 to 100 parts by mass of the solution-polymerized styrene-butadiene rubber when the total amount of the rubber component is 100 parts by mass. The rubber composition for a vibration-proof rubber according to claim 1, which contains 30 to 100 parts by mass of carbon black when the total amount of the rubber component is 100 parts by mass. An anti-vibration rubber obtained by vulcanizing and molding the rubber composition for anti-vibration rubber according to claim 1.