JP2023019875A - High damping rubber composition and base-isolation rubber - Google Patents

Abstract

To provide a high damping rubber composition which is used as a raw material of vulcanized rubber capable of improving three of attenuation performance, shear modulus and critical strain in a balanced manner, and base-isolation rubber obtained using the high damping rubber composition as a raw material.SOLUTION: There are provided a high damping rubber composition which contains a rubber component containing at least isoprene rubber and butadiene rubber, silica and a phenol resin, where when the total amount of the rubber component is 100 pts.mass, a content of the silica is 75-95 pts.mass, and a content of the phenol resin is 10-35 pts.mass; and base-isolation rubber obtained by vulcanizing the high damping rubber composition.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a high damping rubber composition and a seismic isolation rubber.

Background Art Seismic isolation structures, in which rubber layers made of vulcanized rubber and hard layers made of steel plates are alternately laminated, are used for the base isolation of buildings and the bearings of structures such as bridges and elevated roads. This seismic isolation structure is an elastic structure with high rigidity in the vertical direction and low rigidity in the shear direction. It reduces acceleration and minimizes damage to buildings, people, equipment, etc. inside them. Therefore, from the standpoint of improving durability, in addition to damping performance, the seismic isolation rubber that constitutes the seismic isolation structure is required to have improved shear elastic modulus and critical strain.

Patent Document 1 below discloses 100 parts by mass of a diene rubber, 40 to 75 parts by mass of carbon black, 5 to 30 parts by mass of silica, 5 to 55 parts by mass of an inorganic filler, and 5 to 50 parts by mass of a petroleum resin. and the diene rubber contains 80% by mass or more of vinyl-cis-butadiene rubber.

Patent Document 2 below discloses rubber, silica, a silane compound, and a cross-linking component for cross-linking the rubber. and two or more cross-linking accelerators containing 0.4 parts by mass or more and 1.0 parts by mass or less of a guanidine-based accelerator per 100 parts by mass of the total rubber.

JP 2009-149856 A JP 2020-169233 A

As a result of extensive studies by the present inventors, it was found that it is difficult to improve the three properties of damping performance, shear modulus and critical strain in a well-balanced manner in the vulcanized rubber of the rubber composition described in the prior art, and there is room for further improvement. It turns out there is.

The present invention has been developed in view of the above circumstances, and is a high damping rubber composition that is a raw material for vulcanized rubber that can improve the three of damping performance, shear modulus and limit strain in a well-balanced manner. and to provide a seismic isolation rubber obtained by using the high damping rubber composition as a raw material.

The present invention provides a high damping rubber composition containing a rubber component containing at least isoprene rubber and butadiene rubber, silica and a phenolic resin, wherein the content of silica is The present invention relates to a high damping rubber composition containing 75 to 95 parts by mass and containing 10 to 35 parts by mass of the phenolic resin. A vulcanized rubber of such a high damping rubber composition has improved damping performance, shear modulus and critical strain (elongation) in a well-balanced manner.

In the high damping rubber composition, when the total amount of the rubber component is 100 parts by mass, the content of the isoprene rubber is 65 to 85 parts by mass, and the content of the butadiene rubber is preferably 15 to 35 parts by mass. . Further, in the above high damping rubber composition, it is preferable to contain 1 to 15 parts by mass of vinyl-cis-butadiene rubber as the butadiene rubber when the total amount of the rubber component is 100 parts by mass. A vulcanized rubber of a high damping rubber composition having these structures is preferable because both damping performance and limit strain are improved in a particularly well-balanced manner.

As described above, the vulcanized rubber of the high damping rubber composition according to the present invention improves the damping performance, the shear modulus and the critical strain in a well-balanced manner. is particularly useful as

An example of a test piece for damping performance evaluation An example of a stress-strain curve obtained during damping performance evaluation

A high damping rubber composition according to the present invention contains a rubber component containing at least isoprene rubber and butadiene rubber, silica and a phenolic resin.

When the total amount of the rubber component is 100 parts by mass, the content of isoprene rubber is preferably 65 to 85 parts by mass, more preferably 70 to 80 parts by mass. Also, the content of butadiene rubber is preferably 15 to 35 parts by mass, more preferably 20 to 30 parts by mass.

As the butadiene rubber, it is preferable to use a high cis butadiene rubber having a cis content of 95% or more. From the standpoint of improving the damping performance, shear modulus and limit strain in a particularly well-balanced manner, 1 to 15 parts by mass of vinyl-cis-butadiene rubber is used as the butadiene rubber when the total amount of the rubber component is 100 parts by mass. It is preferably contained, more preferably 5 to 15 parts by mass.

The high damping rubber composition according to the present invention may contain diene rubber other than isoprene rubber and butadiene rubber as a rubber component. Diene-based rubbers include natural rubber, styrene-butadiene rubber, butyl rubber, acrylonitrile-butadiene rubber, and the like. However, in order to improve the damping performance, the shear modulus and the limit strain in a well-balanced manner, the content of the diene rubber other than the isoprene rubber and the butadiene rubber is set to: It is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and particularly preferably contains no diene rubber other than isoprene rubber and butadiene rubber.

The high damping rubber composition according to the present invention contains 75 to 95 parts by mass of silica when the total amount of rubber components is 100 parts by mass. As silica, wet silica, dry silica, sol-gel silica, surface-treated silica, etc., which are commonly used for rubber reinforcement, are used. Among them, wet silica is preferable. Moreover, these may be used individually, and may be used in mixture of 2 or more types. The amount of silica compounded in the high damping rubber composition is 75 to 95 parts by mass when the total amount of the rubber component is 100 parts by mass. In particular, when used as a raw material for vibration isolation rubber constituting a seismic isolation structure, in order to maintain high damping properties, the amount of silica compounded in the high damping rubber composition is 80 parts by mass or more per 100 parts by mass of the rubber component. is preferably On the other hand, in order to suppress the deterioration of the processability of the high damping rubber composition, it is more preferable that the amount of silica compounded is 90 parts by mass or less when the total amount of the rubber component is 100 parts by mass.

In the present invention, an organic silane (silane coupling agent) may be blended in order to improve the dispersibility of silica in the high damping rubber composition. Examples of organic silanes include sulfide-based bis-(3-(triethoxysilyl)propyl)tetrasulfide, mercapto-based 3-mercaptopropyltrimethoxysilane, amino-based 3-aminopropyltrimethoxysilane, and vinyl trimethoxysilane. Organosilanes, such as vinyl-based, such as ethoxysilane, are commonly used. These may be used alone or in combination of two or more.

The high damping rubber composition according to the present invention contains 75 to 95 parts by mass of silica when the total amount of rubber components is 100 parts by mass. In order to ensure sufficient damping performance even when the amount of silica is set to such a range, the amount of organic silane should be 4% by mass or less when the amount of silica is 100% by mass. preferable. If the blending amount of the organic silane with respect to silica is out of the above range, the damping performance and the critical strain may be deteriorated due to an increase in the bonding between the silica and the organic silane.

In the high damping rubber composition according to the present invention, when the total amount of rubber components is 100 parts by mass, the content of silica is 75 to 95 parts by mass, and the content of phenolic resin is 10 to 35 parts by mass. When resins other than phenolic resins are used, the shear elastic modulus of the vulcanized rubber tends to deteriorate. However, in the high damping rubber composition according to the present invention, the content of silica is 75 to 95 parts by mass, and the phenolic resin is contained in 10 to 35 parts by mass. improves. If the content of the phenolic resin is less than 10 parts by mass, the effect of improving damping performance and shear modulus is difficult to manifest. On the other hand, if the amount exceeds 35 parts by mass, the processability may be deteriorated due to excessive adhesion to the mixer during processing of the high damping rubber composition, and the limit strain (elongation) of the vulcanized rubber will be deteriorated. Sometimes. The content of the phenolic resin is more preferably 15 to 30 parts by mass when the total amount of the rubber component is 100 parts by mass.

The high damping rubber composition according to the present invention comprises a rubber component containing at least isoprene rubber and butadiene rubber, silica and phenolic resin, organic silane (silane coupling agent), sulfur, a vulcanization accelerator, carbon black, and zinc oxide. , stearic acid, vulcanization accelerators, vulcanization retarders, anti-aging agents, softeners such as waxes and oils, and processing aids. It can be appropriately blended and used within the range.

Examples of carbon black include SAF, ISAF, HAF, FEF and GPF. Carbon black can be used to the extent that rubber properties such as hardness, reinforcing properties, and low heat build-up of vulcanized rubber can be adjusted.

Sulfur may be conventional sulfur for rubber, such as powdered sulfur, precipitated sulfur, insoluble sulfur, highly dispersible sulfur, and the like.

As vulcanization accelerators, sulfenamide-based vulcanization accelerators, thiuram-based vulcanization accelerators, thiazole-based vulcanization accelerators, thiourea-based vulcanization accelerators, and guanidine-based vulcanization accelerators, which are commonly used for rubber vulcanization. Vulcanization accelerators such as accelerators and dithiocarbamate-based vulcanization accelerators may be used singly or in an appropriate mixture.

Antiaging agents include aromatic amine antiaging agents, amine-ketone antiaging agents, monophenol antiaging agents, bisphenol antiaging agents, polyphenol antiaging agents, and dithiocarbamic acid, which are commonly used for rubber. Antiaging agents such as salt-based anti-aging agents and thiourea-based anti-aging agents may be used singly or in combination as appropriate.

The high damping rubber composition according to the present invention comprises a rubber component containing at least isoprene rubber and butadiene rubber, silica and phenolic resin, organic silane (silane coupling agent), sulfur, a vulcanization accelerator, carbon black, and zinc oxide. , stearic acid, vulcanization accelerators, vulcanization retarders, anti-aging agents, softeners such as waxes and oils, compounding agents normally used in the rubber industry such as processing aids, etc. It is obtained by kneading using a kneader used in the usual rubber industry such as.

In addition, the method of blending each of the above components is not particularly limited, and a method of kneading in advance blending components other than vulcanization system components such as sulfur and vulcanization accelerators to form a masterbatch, adding the remaining components, and further kneading. , a method of adding each component in an arbitrary order and kneading, a method of adding all the components at the same time and kneading, and the like.

The seismic isolation rubber according to the present invention is formed by molding an unvulcanized high damping rubber composition obtained by kneading using a roll or an extruder with a roller head into a sheet, and then into a disc. After punching, steel sheets (hard layers) and unvulcanized sheet-like rubber layers (high damping rubber composition) are alternately laminated, and vulcanized at a predetermined temperature while applying pressure as necessary. can be manufactured by

It is preferable to apply a vulcanizing adhesive before laminating the hard layer and the rubber layer. As the vulcanizing adhesive, one having excellent adhesiveness between the steel plate and the rubber may be appropriately selected.

The seismic isolation rubber according to the present invention improves the damping performance, the shear elastic modulus, and the critical strain in a well-balanced manner, regardless of the size, the peculiarity of the shape, and the like. Therefore, the vibration isolation rubber according to the present invention can be suitably used for seismic isolation structures that require particularly high damping properties and durability.

EXAMPLES The present invention will be explained more specifically below by describing Examples.

(Preparation of rubber composition)
The rubber compositions of Examples 1 to 7 and Comparative Examples 1 to 4 were blended with 100 parts by mass of the rubber component according to the formulation shown in Table 1, and kneaded using a conventional Banbury mixer to prepare rubber compositions. bottom. Each compounding agent described in Table 1 is shown below.

(a) Isoprene rubber (trade name “IR2200L”, manufactured by Zeon Corporation)
(b) Butadiene rubber-1 (trade name “CB22”, manufactured by Lanxess)
(c) Butadiene rubber-2 (vinyl-cis-butadiene rubber) (trade name “UBEPOL VCR617” manufactured by Ube Industries, Ltd. (d) Silica (trade name “Nipsil AQ” manufactured by Tosoh Silica Corporation)
(e) Organic silane (silane coupling agent) (trade name “Si69”, manufactured by Evonik Degussa)
(f) Carbon black (trade name “SEAST 6”, manufactured by Tokai Carbon Co., Ltd.)
(g) Phenolic resin (trade name “Sumilite Resin PR-13349” manufactured by Sumitomo Bakelite Co., Ltd. (h) Alicyclic hydrocarbon resin (trade name “Quinton 1340” manufactured by Nippon Zeon Co., Ltd.)
(i) Oil (trade name “Process X-140”, manufactured by JX Nippon Oil & Energy Corporation)
(j) Zinc oxide (trade name “Zinchua No. 3”, manufactured by Mitsui Mining & Smelting Co., Ltd.)
(k) Fatty acid (trade name “industrial stearic acid”, manufactured by Kao Corporation)
(l) Antiaging agent (trade name “Nocrac 6C”, manufactured by Ouchi Shinko Kagaku Co., Ltd.)
(m) Sulfur (trade name “5% oil treated sulfur”, manufactured by Hosoi Chemical Industry Co., Ltd.)
(n) Vulcanization accelerator 1 (trade name "Noccellar NS-P", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)
(o) Vulcanization accelerator 2 (trade name "Noccellar D", manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.)
(p) Retarder (N-cyclohexylthiophthalimide) (trade name “Retarder CTP”, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)

Each rubber composition was vulcanized at 150° C. for 30 minutes using a predetermined mold to prepare a vulcanized rubber, and the properties were evaluated.

<Damping performance and shear modulus>
A "two-block, wrap-and-share" test piece (rubber part: width 25 mm, length 25 mm, thickness 5 mm) shown in FIG. At 0.5 Hz, shear excitation is applied under the following strain conditions, and a stress-strain curve as shown in FIG. 2 is obtained. The measurement temperature was 20°C.
(Distortion vibration conditions)
Vibration is applied 10 times at ±175% of the thickness of the specimen.
From the stress-strain curve shown in FIG. 2, the shear elastic modulus (Geq) and equivalent damping constant (Heq) are calculated from the following equations (1) and (2), respectively, and the average value of 10 excitations is the shear stress of the rubber. The elastic modulus and the equivalent damping constant were used.
Geq (N/mm ² )=F/2 (1)
Heq(%)=(ΔW/(W1+W2))×1/2π×100 (2)
where ΔW is the area within the loop of the stress-strain curve in FIG. 2, and W1 and W2 are the areas of the triangular regions in FIG. 3, respectively. In addition, evaluation of damping property was evaluated based on the value of Heq (%). A larger Heq means a higher damping performance, and a larger Geq means a higher shear modulus.

The shear elastic modulus (Geq) and equivalent damping constant (Heq) of the vulcanized rubber obtained in Comparative Example 1 are indexed to 100, and the shear elasticity of the vulcanized rubber obtained in each example and comparative example is evaluated. rate (Geq) and equivalent damping constant (Heq) were evaluated. Table 1 shows the results.

<Limited strain (elongation)>
Based on JIS-K 6251, the elongation (EB) of the vulcanized rubber was evaluated. Evaluation was performed by index evaluation when the EB (%) of the vulcanized rubber obtained in Comparative Example 1 was set to 100. A larger value means that the vulcanized rubber has a higher elongation rate and a larger limit strain. Table 1 shows the results.

From the results in Table 1, it can be seen that the vulcanized rubbers of the rubber compositions according to Examples 1 to 7 have improved damping performance, shear modulus and critical strain in a well-balanced manner. On the other hand, in the vulcanized rubber of the rubber composition according to Comparative Example 2, the amount of silica compounded is 70 parts by mass when the total amount of the rubber component is 100 parts by mass. It can be seen that the improvement effect of In addition, the vulcanized rubber of the rubber composition according to Comparative Example 3 has a phenolic resin content of 5 parts by mass when the total amount of the rubber component is 100 parts by mass. It can be seen that the rate improvement effect is low. Furthermore, it can be seen that the vulcanized rubber of the rubber composition according to Comparative Example 4 has extremely poor damping performance due to the use of a resin other than the phenolic resin.

Claims (4)

A high damping rubber composition containing a rubber component containing at least isoprene rubber and butadiene rubber, silica and a phenolic resin,
A high damping rubber composition, wherein the silica content is 75 to 95 parts by mass and the phenolic resin content is 10 to 35 parts by mass when the total amount of the rubber component is 100 parts by mass. The high damping rubber composition according to claim 1, wherein the content of the isoprene rubber is 65 to 85 parts by mass and the content of the butadiene rubber is 15 to 35 parts by mass when the total amount of the rubber component is 100 parts by mass. . 3. The high damping rubber composition according to claim 1, wherein the butadiene rubber contains 1 to 15 parts by mass of vinyl-cis-butadiene rubber when the total amount of the rubber component is 100 parts by mass. A vibration isolation rubber obtained by vulcanizing the high damping rubber composition according to any one of claims 1 to 3.

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