JP3325775B2 - Rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition used for a vibration-isolating rubber and a seismic isolation isolator.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for seismic isolation isolators capable of giving a long natural period to buildings and structures, and accordingly, there has been a demand for the development of rubber materials having a low shear modulus. .

That is, the natural period T of the seismic isolation structure is generally expressed by the following equation: T = 2π (m / k) ^1/2 (where m represents the mass of the structure and k represents the spring constant of the seismic isolation isolator) The spring constant k is generally given by the following equation: k = GA / nt (where G is the shear modulus of rubber, A is the cross-sectional area of the seismic isolation isolators, n is the number of rubber layers, and t is Of the rubber.).

Therefore, in order to lengthen the natural period, a rubber material having a low shear modulus may be used.

As a method for lowering the shear modulus of a rubber material, a method of blending a process oil, a plasticizer, or the like is generally known.

However, in this method, compression set and creep characteristics may be reduced, and since the compounding agent is liquid at room temperature, if it is compounded in a large amount, it exudes from the rubber surface to deteriorate the characteristics. Bleeding phenomenon. Such a bleed phenomenon is particularly problematic for seismic isolation isolators and vibration isolating rubbers to which a large vertical load is applied.

[0007]

As described above, recently, as a rubber composition used for a vibration isolating rubber or a seismic isolation isolator,
Although a material with a low shear modulus is required, satisfactory properties have not yet been obtained, such as inadequate compression set and creep properties, or bleeding of the compounding agent. It is.

The present invention has been made in view of the above circumstances, and has a low shear modulus, no risk of bleeding, and excellent compression set, creep characteristics and other properties. It is intended to provide a composition.

[0009]

Means for Solving the Problems The rubber composition of the present invention comprises:
For 100 parts by weight of rubber, vinyl toluene and indene
It is characterized by comprising 1 to 30 parts by weight of an aliphatic cyclic saturated hydrocarbon resin obtained by hydrogenating a polymer as a main polymerization component (hereinafter referred to as an alicyclic saturated hydrocarbon resin). .

The rubber used in the present invention is not particularly limited, and includes natural rubber (NR), styrene butadiene rubber (SBR), isoprene rubber (IR),
Various synthetic rubbers such as chloroprene rubber (CR), butyl rubber, butadiene rubber (BR), and acrylonitrile butadiene rubber can be used. Among them, use of natural rubber having good creep characteristics is desirable, and other synthetic rubbers are preferable. When used together, it is desirable that at least 50% by weight or more of the natural rubber be blended with the entire rubber.

In the present invention, the alicyclic saturated hydrocarbon resin to be mixed with such a rubber is a solid at room temperature, and is one or more of those generally known as alicyclic saturated hydrocarbon resins. Can be arbitrarily selected and used. In the present invention, among others, the softening point is 25%.
~ 160 ° C is preferred. If the softening point is less than 25 ° C, bleeding may occur on the surface.
If the temperature exceeds ℃, the reduction of the shear modulus becomes insufficient. Specifically, Alcon P-70, Alcon P-90, Alcon P-100, Alcon P-115, Alcon P-125, and Alcon P-140 (all of which are trade names) manufactured by Arakawa Chemical Industries, Ltd. It is preferably used.

In the present invention, such an alicyclic saturated hydrocarbon resin is blended at a ratio of 1 to 30 parts by weight with respect to 100 parts by weight of the rubber. If the amount of the alicyclic saturated hydrocarbon resin is less than 1 part by weight per 100 parts by weight of rubber, the shear modulus cannot be sufficiently reduced, and if it exceeds 30 parts by weight, the tensile strength, etc. Becomes insufficient.

In the rubber composition of the present invention, in addition to the above components, fillers such as ferrite powder and carbon black which are usually compounded in rubber, antioxidants, processing aids, vulcanization accelerators, vulcanization accelerators Additives such as auxiliaries can be added within a range that does not impair the effects of the present invention.

In the rubber composition of the present invention, the addition of the alicyclic saturated hydrocarbon resin can reduce the shear modulus without lowering the compression set and creep properties, Since the saturated hydrocarbon resin is solid at room temperature, it does not bleed to the surface as in conventional process oils. Accordingly, the shear modulus of elasticity is low, there is no risk of bleeding, and excellent properties such as compression set and creep properties are obtained.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples.

Examples 1 to 5 An alicyclic saturated hydrocarbon resin (number average molecular weight) obtained by polymerizing natural rubber (SMR CV-60), vinyltoluene and indene as main polymerization components and then hydrogenating the same. 860, softening point
140 ° C), carbon black (Chubu Carbon Co., Ltd., product name HTC ^# 80), stearic acid, zinc white, sulfur,
The vulcanization accelerator and the vulcanization accelerator were uniformly mixed at a ratio shown in Table 1 using a kneader to obtain a rubber composition.

Next, the obtained rubber composition was
A low elongation stress test, a compression set test and a tensile test specified in SK 6301 were performed, and a 25% low elongation stress, a compression set rate, a tensile strength and an elongation were measured. In addition, the shear modulus was determined from the value of 25% low elongation stress obtained by the low elongation stress test.
Calculated based on JIS K 6386 (6). Table 1 shows the results.

Incidentally, the low elongation stress test and the tensile test
For a sample sheet of the rubber composition obtained by vulcanization under the conditions of 150 ° C. × 30 minutes, the compression set test was performed at 150 ° C.
The test was performed on a sample sheet obtained by vulcanization under the conditions of × 40 minutes.

Comparative Examples 1 to 5 As comparative examples, examples in which an alicyclic saturated hydrocarbon resin was not blended (Comparative Example 1) and examples in which an alicyclic saturated hydrocarbon resin was excessively blended (Comparative Example 2) ), Examples (Comparative Examples 3 to 5) in which a process oil (commercial No. 2 manufactured by Nippon Oil Co., Ltd.) was blended in place of the alicyclic saturated hydrocarbon resin,
The same property evaluation test as in the example was performed. The results are shown in Table 1 together with the mixing ratio of each component.

[0020]

[Table 1] As is clear from Table 1, the rubber composition according to the present invention was able to realize a low shear modulus without lowering the compression set characteristics and the tensile strength. Comparative Example 2 in which aromatic saturated hydrocarbon resin was excessively blended
In Comparative Examples 3 to 5, in which the tensile strength decreased, and in Comparative Examples 3 to 5 in which the process oil was blended, the compression set characteristics decreased.

[0021]

As is clear from the above examples, according to the rubber composition of the present invention, vinyl toluene is added to rubber.
Hydrogenation of a polymer containing ethylene and indene as the main polymerization components
The alicyclic saturated hydrocarbon resin is blended in a predetermined ratio, so that the shear modulus can be lowered without deteriorating the excellent properties inherent in rubber, such as compression set characteristics and creep characteristics. And bleeding does not occur. Therefore, it is useful as a rubber composition for a vibration-proof rubber or a seismic isolation isolator requiring a low shear modulus.

[0022]

──────────────────────────────────────────────────続 き Continuation of the front page (72) Keiichi Takayama 2-1, 1-1 Sakae Oda, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Showa Electric Cable Co., Ltd. (56) References JP-A-7-330989 (JP, A JP, 9-309978 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 21/00 C08L 7/00 C08L 9/00 C08L 45/00-45/02

Claims (3)

(57) [Claims] 1. 100 parts by weight of rubber and vinyl toluene
Hydrogenation of a polymer containing as a main polymerization component
A rubber composition comprising 1 to 30 parts by weight of an aliphatic cyclic saturated hydrocarbon resin. 2. The rubber composition according to claim 1, wherein the aliphatic cyclic saturated hydrocarbon resin has a softening point of 25 to 160 ° C. 3. The rubber composition according to claim 1, wherein a main component of the rubber is natural rubber.