JP4120582B2 - Anti-vibration rubber composition and anti-vibration rubber obtained thereby - Google Patents

Description

  The present invention relates to an anti-vibration rubber composition that can be widely used as an anti-vibration rubber for vehicles such as automobiles, and to an anti-vibration rubber obtained thereby.

  In automobiles, for the purpose of reducing vibration and noise, vibration-proof rubber is usually used for strut mounts, stabilizer bushes, suspension bushings, engine mounts, and the like. The rubber composition constituting the anti-vibration rubber is preferably low in rigidity from the viewpoint of reducing vibration and noise. However, if the rigidity is too low, the steering stability of the automobile is adversely affected. For this reason, the anti-vibration rubber is required to have a trade-off between reducing vibration and noise and ensuring steering stability.

  Here, vibration and noise are dynamic elements in a relatively high frequency region (100 Hz or more), whereas steering stability is a static element with little movement. The vibration-proof performance is better as the spring constant (dynamic spring constant) when transmitting vibration is smaller, while the support performance (strength) is better as the static spring constant indicating the support rigidity is larger. Therefore, it is said that a rubber having a smaller value of dynamic magnification (dynamic spring constant / static spring constant), which is a ratio between the dynamic spring constant and the static spring constant, is superior as a vibration-proof rubber for automobiles.

Conventionally, various studies have been made to reduce the dynamic magnification. That is, for example, low dynamic magnification was achieved by containing carbon black having a large particle size in the rubber composition or increasing the crosslinking density of the rubber (see Patent Document 1).
JP-A-8-73658

  However, when a large particle size carbon black is contained, the elongation at break of the rubber is lowered, and the reinforcing property is deteriorated accordingly. On the other hand, if the crosslinking density of the rubber is increased, the durability, breaking strength and breaking elongation are lowered and the reinforcing property is deteriorated.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vibration-proof rubber composition having a small dynamic magnification, excellent vibration-proof characteristics, and excellent reinforcing properties, and a vibration-proof rubber obtained thereby. And

In order to achieve the above object, the present invention provides a vibration-proof rubber composition containing the following (A) to (E) as essential components, as a first gist, and uses the vibration-proof rubber composition. The vibration rubber is a second gist.
(A) Diene rubber.
(B) Organized layered clay mineral.
(C) Methacrylic acid-modified liquid isoprene rubber.
(D) Amine-based silane coupling agent.
(E) Epoxidized modified elastomer.

That is, the present inventor has intensively studied to solve the above problems. In the course of this research, organically layered clay minerals (organic stratified clay minerals such as montmorillonite were organically treated with organic onium ions, etc.) were dispersed in a rubber composition containing diene rubber as a polymer component. An attempt was made to obtain reinforcement. And when the methacrylic acid-modified liquid isoprene rubber is used in combination with the diene rubber, and the organic layered clay mineral is mixed with it, the liquid isoprene rubber enters between the layers of the clay mineral, and acts to peel off each layer. For this reason, it was found that nano-dispersion of clay minerals was effectively performed, and as a result, high reinforcement could be obtained even if the clay mineral filling ratio was small. However, as it is, the bond between the organically modified lamellar clay mineral and the rubber polymer is still insufficient, and there is a limit to the improvement of the dynamic characteristics. Therefore, as a result of further research, the present inventor further blended an amine-based silane coupling agent and an epoxidized modified elastomer, and these are combined with a hydroxyl group (—OH) at the end of the organic layered clay mineral. Recalling that it reacts with a functional group, it experimented. That is, this enables the nano-dispersed organic layered clay mineral to be chemically bonded to the rubber polymer, thereby reducing the viscosity effect between the rubber polymer and the organic layered clay mineral. As a result, the dynamic spring constant decreases, so that it is possible to achieve a reduction in dynamic magnification that could not be achieved by the conventional reinforcement with carbon black without impairing the reinforcing property and the vibration isolating characteristic. Here, the nano-dispersion is usually dispersed in a rubber polymer and dispersed in a state where the size of the organically modified layered clay mineral is on the order of nanometers (1 × 10 ⁻⁷ to 1 × 10 ⁻⁹ m). For example, in the case of a plate-like crystal of an organized layered clay mineral having a thickness of about 1 nm and a length of about 50 to 1000 nm, the interlayer distance (intercrystal distance) is generally about 30 to 85 mm or more. The interlayer distance is measured by, for example, an X-ray diffraction method.

  As described above, the anti-vibration rubber composition of the present invention comprises a diene rubber as a main component, an organic layered clay mineral, a methacrylic acid-modified liquid isoprene rubber, an amine-based silane coupling agent, and an epoxidized modified elastomer. Containing. And since the said layered clay mineral exists in the state which was effectively nano-dispersed in the rubber composition, and is considered to be firmly bonded to the rubber polymer, the obtained vibration-proof rubber is reinforced. In addition to excellent performance and vibration-proof characteristics, a low dynamic magnification can be achieved. And this anti-vibration rubber | gum can be used suitably as an anti-vibration member for motor vehicles.

  In particular, when the content ratio of the amine-based silane coupling agent is in the range of 1 to 5 parts by weight with respect to 100 parts by weight of the main component diene rubber, a vibration-isolating rubber having a lower dynamic magnification is obtained. Be able to.

  Further, if the content of the epoxidized modified elastomer is in the range of 1 to 5 parts by weight with respect to 100 parts by weight of the main component diene rubber, the rubber properties as a vibration-proof rubber are adversely affected. No reduction in dynamic magnification is achieved.

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

  The anti-vibration rubber composition of the present invention comprises a diene rubber (A) as a main component, an organic layered clay mineral (B), a methacrylic acid-modified liquid isoprene rubber (C), and an amine silane coupling agent (D ) And an epoxidized modified elastomer (E). Here, the “main component” means a substance that greatly affects the properties of the composition, and usually means that it accounts for 50% by weight or more of the whole. In the present invention, the organically layered clay mineral of the component (B) is usually nano-dispersed, and the nano-dispersed organically layered clay mineral is contained by the inclusion of the component (D) and the component (E). The clay mineral can be chemically bonded to the diene rubber (A), which is a polymer component, and the friction (viscosity effect) between the diene rubber and the organically modified layered clay mineral is reduced. As a result of the lowering of the constant, it is possible to achieve a lower dynamic magnification that could not be achieved by the conventional reinforcement with carbon black without impairing the reinforcing property and the vibration isolating property.

  Examples of the diene rubber of the component (A) include natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), chloroprene rubber (CR) and the like. These may be used alone or in combination of two or more.

  Examples of the organically modified layered clay mineral (component (B)) used together with the component (A) include, for example, smectite-based layered clay minerals such as montmorillonite, saponite, hectorite, beidellite, nontronite, soconite, and stevensite, Examples thereof include those obtained by organically treating a conventionally known layered clay mineral having a cation exchange ability such as vermiculite, halloysite, mica and the like with an organic onium ion. The metal cation existing between the layers of these clay minerals is exchanged for organic onium ions by the organic treatment. For this reason, the organic onium ions are ion-bonded to the clay mineral, and this increases the interlayer distance of the clay mineral, so that the organic layered clay mineral is easily nano-dispersed. Such organically modified layered clay minerals may be used alone or in combination of two or more.

  The organic onium ion is not particularly limited, but those having 6 or more carbon atoms are preferably used. Specifically, such organic onium ions include hexyl ammonium ion, octyl ammonium ion, 2-ethylhexyl ammonium ion, dodecyl (laryl) ammonium ion, octadecyl (stearyl) ammonium ion, dioctyl dimethyl ammonium ion, and trioctyl ammonium ion. , Ammonium ions such as distearyldimethylammonium ion, phosphonium ions, oxonium ions, sulfonium ions, and the like. These may be used alone or in combination of two or more.

  The blending ratio of the component (B) is preferably set in the range of 3 to 20 parts, more preferably 100 parts by weight (hereinafter abbreviated as “part”) of the diene rubber of the component (A). Is in the range of 5 to 15 parts. That is, if the amount of the organically modified layered clay mineral is less than 3 parts, it is difficult to sufficiently achieve the intended effect of the present invention. This is because the inter-particle distance approaches and the spring constant in the low strain region increases.

  The methacrylic acid-modified liquid isoprene rubber [component (C)] used together with the components (A) and (B) is obtained by methacrylate or acrylate the liquid isoprene rubber. The rubber structure has a structure in which a maleic acid unit, a methacryloyl group, or an acryloyl group is introduced. Especially, the liquid rubber material shown by following General formula (1) is used suitably. In the general formula (1), the molecular weight is preferably 10,000 to 30,000. The alkyl group (Y) in the formula is preferably a lower alkyl group such as ethylene, propylene, butylene. And these are used individually or in combination of 2 or more types.

  The blending ratio of the component (C) is preferably set in the range of 1 to 10 parts, more preferably in the range of 2 to 5 parts with respect to 100 parts of the diene rubber of the component (A). That is, if the methacrylic acid-modified liquid isoprene rubber is less than 1 part, nano-dispersion of the organically modified lamellar clay mineral is difficult to be performed advantageously. This is because it may adversely affect

  The amine-based silane coupling agent [component (D)] used together with the components (A) to (C) is not particularly limited, and examples thereof include γ-aminopropyltrimethoxysilane and γ-aminopropyltrimethyl. Examples thereof include ethoxysilane. These may be used alone or in combination of two or more.

  The blending ratio of the component (D) is usually set in the range of 1 to 10 parts, preferably in the range of 1 to 5 parts, with respect to 100 parts of the diene rubber of the component (A). That is, by adding the amine-based silane coupling agent of component (D) within the preferred range, a lower dynamic magnification can be achieved.

  The epoxidized modified elastomer [(E) component] used together with the above components (A) to (D) is not particularly limited, and examples thereof include epoxidized natural rubber (ENR) and the like containing the epoxy. Examples thereof include those prepared so that the amount is 25 to 50% by weight.

  The blending ratio of the component (E) is usually set in the range of 1 to 10 parts, preferably in the range of 1 to 5 parts, with respect to 100 parts of the diene rubber of the component (A). . That is, by blending the epoxidized modified elastomer of the component (E) within the preferred range, a low dynamic magnification can be achieved without adversely affecting the rubber characteristics as a vibration-proof rubber.

  In addition to the components (A) to (E), the anti-vibration rubber composition of the present invention includes a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, an anti-aging agent, a processing aid, and a softening agent. You may mix | blend an agent, a filler, etc. as needed.

  Sulfur is preferably used as the vulcanizing agent. The amount of sulfur is preferably in the range of 0.3 to 10 parts, particularly preferably in the range of 0.5 to 5 parts, with respect to 100 parts of the diene rubber of the component (A).

  The vulcanization accelerator is not particularly limited. For example, thiazole accelerator, thiuram accelerator, N-cyclohexyl-2-benzothiazylsulfenamide (CBS), dibenzothiazyl disulfide (MBTS), 2 -Sulfenamide accelerators such as mercaptobenzothiazole (MBT) and tetramethylthiuram monosulfide (TMTM).

  The blending amount of the vulcanization accelerator is preferably in the range of 0.1 to 3 parts, particularly preferably in the range of 0.5 to 2 parts, with respect to 100 parts of the diene rubber of the component (A). is there.

  The vulcanization aid is not particularly limited, and examples thereof include zinc oxide (ZnO) and magnesium oxide. These may be used alone or in combination of two or more.

  The blending amount of the ZnO is preferably 10 parts or less with respect to 100 parts of the diene rubber of the component (A). If it is in such a range, it will be in a normal range, and there will also be no problem of the weight increase of the product accompanying the increase in ZnO.

  Examples of the antiaging agent include carbamate type antiaging agent, phenylenediamine type antiaging agent, phenol type antiaging agent, diphenylamine type antiaging agent, quinoline type antiaging agent, and waxes.

  The blending amount of this anti-aging agent is preferably in the range of 1 to 7 parts, particularly preferably in the range of 2 to 5 parts, with respect to 100 parts of the diene rubber of the component (A).

  Examples of processing aids include stearic acid, fatty acid esters, fatty acid amides, and hydrocarbon resins.

  The blending amount of the processing aid is preferably in the range of 1 to 5 parts, particularly preferably in the range of 1 to 3 parts, relative to 100 parts of the diene rubber of the component (A).

  The anti-vibration rubber of the present invention is a rubber obtained by kneading the components essential to the components (A) to (E) with a closed kneader (Banbury type), a roll, a twin-screw kneading extruder, etc. Using the composition, it can be produced by vulcanization molding by a conventionally known method such as mold molding or press molding to obtain a desired shape. At the time of preparing the rubber composition, a part of the main component (A) diene rubber (about 50% by weight), (B) the organic layered clay mineral, and (C) After kneading with methacrylic acid-modified liquid isoprene rubber, etc., the kneaded product is kneaded with the remaining diene rubber (about 50% by weight) (masterbatch method), and organically becomes more effective in the diene rubber. Since the layered clay mineral can be nano-dispersed, it is preferable.

  The use of the vibration-proof rubber of the present invention is not particularly limited, but it can be suitably used for a rubber member for vibration-proof of a vehicle such as an automobile. For example, strut mount, stabilizer bush, suspension bush, engine mount, body mount, cab mount, member mount, strut bar cushion, center bearing support, torsional damper, steering rubber coupling, tension rod bush, lower ring bush, arm bush, It can be suitably used for bump strappers, FF engine roll stoppers, muffler hangers, and the like.

  Next, examples will be described together with comparative examples.

[Examples 1 to 5, Comparative Examples 1 to 4]
By preparing the materials shown below and blending them in the proportions shown in Tables 1 and 2 below, these are kneaded (kneading by the master batch method) using a closed kneader (Banbury type) or roll. A rubber composition was prepared. In addition, when measured by the X-ray diffraction method, the interlayer distance (distance between crystals) of the plate-like crystals of the organized layered clay mineral in Examples 1 to 5 and Comparative Examples 3 and 4 was about 30 to 85 mm.

[Natural rubber (component A)]
RSS # 3

[Zinc oxide]
2 types of zinc oxide, made by Mitsui Mining & Mining

〔stearic acid〕
LUNAC S30, manufactured by Kao

〔Carbon black〕
Seast SO, manufactured by Tokai Carbon

[Vulcanization accelerator]
Sunseller CZ-G, manufactured by Sanshin Chemical Co., Ltd.

〔sulfur〕
Sulfur-PTC, manufactured by Daito Sangyo

[Organized layered clay mineral (component B)]
Esven NX, made by Hojun Co.

[Methacrylic acid modified liquid isoprene rubber (component C)]
UC-1, made by Kuraray

[Amine-based silane coupling agent (component D)]
TSL8331 (γ-aminopropyltriethoxysilane), manufactured by GE Toshiba Silicone

[Epoxidized natural rubber (E component)]
ENR50 (epoxy content 50%)

  Using the rubber compositions of Examples and Comparative Examples thus obtained, press vulcanization was performed at 150 ° C. for 20 minutes to produce a cylindrical vibration-proof rubber test piece having a diameter of 50 mm and a thickness of 25 mm. . And each characteristic was measured and evaluated in accordance with the following method using this rubber test piece. The results are shown in Tables 3 to 4 below.

[Normal properties]
The normal physical properties (TB, EB, Hs) were measured according to JIS K 6251.
TB: Strength at break (MPa)
EB: Elongation at break (%)
Hs: Hardness (JIS A)

[Spring characteristics]
The dynamic spring constant (Kd100) and the static spring constant (Ks) were measured according to JIS K 6394, respectively. Based on this value, the dynamic magnification (Kd100 / Ks) was calculated.

  From the above results, it can be seen that all of the example products are excellent in normal physical properties and in spring characteristics. All the products of the examples are set in a region where the static spring constant is high, and realize a low dynamic magnification. Therefore, it can be seen that the products of the examples are useful for vibration-proof rubber applications for vehicles such as automobiles.

  In contrast, Comparative Examples 1 and 2 contain carbon black in order to eliminate the decrease in spring constant, but as the content increases, the breaking strength and breaking elongation decrease, or the dynamic magnification It can be seen that there is a harmful effect of increasing. Moreover, it turns out that the comparative example 3 goods make the static spring constant high by replacing with carbon black, but making the static spring constant high by containing an organic layered clay mineral. The product of Comparative Example 4 uses an amine silane coupling agent in order to reduce the dynamic magnification, but it can be seen that the normal state physical properties and spring characteristics are generally lowered.

Claims (4)

An anti-vibration rubber composition comprising the following (A) to (E) as essential components:
(A) Diene rubber.
(B) Organized layered clay mineral.
(C) Methacrylic acid-modified liquid isoprene rubber.
(D) Amine-based silane coupling agent.
(E) Epoxidized modified elastomer.   The anti-vibration rubber composition according to claim 1, wherein the content of the amine silane coupling agent of the component (D) is in the range of 1 to 5 parts by weight with respect to 100 parts by weight of the component (A).   The anti-vibration rubber composition according to claim 1 or 2, wherein the content of the epoxidized modified elastomer of the component (E) is in the range of 1 to 5 parts by weight with respect to 100 parts by weight of the component (A).   An anti-vibration rubber comprising the anti-vibration rubber composition according to any one of claims 1 to 3.