JPH04216836A - Vibration-damping material - Google Patents

Abstract

PURPOSE:To obtain a vibration-damping material excellent in vibration-damping performances and useful as a foundation quake resisting system by vulcanizing a composition prepared by mixing a natural rubber with a specified filler. CONSTITUTION:This material is prepared by vulcanizing a composition prepared by mixing 100 pts.wt. natural rubber with 5-100 pts.wt. magnesium silicate of a mean particle diameter of 2-1mum as a filler.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in vibration damping materials used in buildings, general equipment, and the like.

0002

[Prior Art] Conventionally, base isolation systems for the purpose of isolating the foundations and floors of buildings or general equipment during large earthquakes have been made using laminated rubber made by laminating rubber and metal plates, and steel dampers. It is common practice to use both together. This steel damper has the drawback that it requires time and money for construction work and maintenance, and it also narrows the underground space of buildings, preventing its effective use.
Recently, there has been a strong demand for seismic isolation using only laminated rubber by improving the damping performance of the damping rubber material without using it in combination.

[0003]The properties required of such a high-damping rubber material are to have an elongation of 600% or more so that it can follow large horizontal displacements of the laminated rubber while maintaining the creep characteristics necessary for the laminated rubber. Furthermore, the damping performance is significantly improved. In addition, in order to significantly improve damping performance, we changed the viscoelastic behavior of the composition, and as a specific characteristic, we changed the equivalent damping constant to the operating temperature (approximately -10 to 40°C).
It is also necessary to keep the damping characteristics constant within the operating temperature range by making the temperature dependence of the elastic modulus as large as possible within the range and minimizing the temperature dependence of the elastic modulus (change in the elastic modulus due to temperature).

On the other hand, conventional damping rubber materials for laminated rubber are based on natural rubber, which has good creep properties and other mechanical properties, and in addition, styrene-butadiene rubber (SBR), butadiene rubber (BR), Often used is a blend of rubber such as isoprene rubber, carbon black or graphite added as a filler to improve damping performance, an appropriate plasticizer, etc., and vulcanization. In other words, it is almost impossible to use rubber other than natural rubber as the base rubber in terms of creep properties and other mechanical properties, but since natural rubber itself has extremely low damping performance, it is difficult to use other polymers or additives. It is being considered to improve the damping performance by adding agents. However, the current situation is that it has not yet been possible to obtain properties that satisfactorily satisfy the various damping performances described above while maintaining good creep properties and mechanical properties of natural rubber.

[0005]

[Problems to be Solved by the Invention] In view of the above points, the present invention has been developed to significantly improve damping performance in the temperature range of about -10 to 40°C while maintaining the good mechanical properties of natural rubber. The object is to provide a vibration damping material with improved high damping.

[0006]

[Means for Solving the Problems] The present invention is made by vulcanizing a composition in which 100 parts by weight of natural rubber is blended with 5 to 100 parts by weight of magnesium silicate having an average particle size of 2 to 10 μm as a filler. The present invention relates to a vibration damping material characterized by:

[0007] In order to solve the above-mentioned problems in compositions using natural rubber as a base resin, which has good mechanical properties including creep properties, as a rubber material for laminated rubber, the present inventors used natural rubber and various additives. As a result of considering the combination with the agent,
If a predetermined amount of magnesium silicate with an average particle size of 2 to 10 μm is blended as a filler and vulcanized, most of the mechanical properties such as the good elongation properties (600% or more) and tensile strength of natural rubber itself are lost. The inventors of the present invention have discovered that the damping performance can be greatly improved without any problems, and that stable performance can be achieved in the operating temperature range of -10 to 40° C., leading to the present invention.

In the present invention, natural rubber having good mechanical properties such as creep properties is used as the base rubber, and other rubbers or resins may be used in combination with this as appropriate. When used together, chloroprene rubber with relatively good mechanical properties and acrylonitrile-butadiene rubber (N
BR) is preferred. NBR containing 10 to 30% acrylonitrile and carboxy-modified NBR are preferable because they have excellent compatibility with natural rubber and greatly improve damping performance.

In the present invention, at least magnesium silicate is blended into the base rubber as a filler. The average particle size of magnesium silicate used is in the range of 2 to 10 μm. When the average particle size is smaller than 2 μm, the reinforcing effect on the composition is too high, resulting in disadvantages such as a decrease in elongation and a shortening of the linear region of the stress-strain curve of the composition. There is little improvement in damping performance. In addition, the blending amount is in the range of 5 to 100 parts by weight per 100 parts by weight of natural rubber; if it is less than this, the improvement in damping performance will be small, and if it is more than this, it will cause a decrease in elongation, etc. Mechanical properties may be impaired.

The vibration damping material of the present invention is produced by thoroughly mixing these components in predetermined proportions at a temperature of 60 to 70° C. and vulcanizing the mixture by a conventional method. In the mixing stage, reinforcing fillers such as Carn black, process oil, ferrite powder, fillers for improving damping performance such as nylon fibers grafted with natural rubber, etc., may be added within a range that does not impair the effects of the present invention. It can be added as appropriate. Nylon fibers with natural rubber grafted onto them include short nylon fibers with natural rubber chemically grafted onto their surfaces. For example, when the ratio (weight) of nylon fibers and natural rubber is 1:2, the average diameter Approximately 0.2 μm or more,
There is a product name such as FRR (manufactured by Ube Industries, Ltd.) with a length of about 1 mm, and (a) 5 to 100 parts by weight of natural rubber.
It is preferable to mix it in a proportion of 30 parts by weight because the damping performance is further improved. Note that when the vibration damping material of the present invention is used in a laminated rubber, the final hardness after vulcanization is 40 to 70 degrees in JIS-A hardness.

As described above, in the present invention, natural rubber having good mechanical properties such as creep properties is used as a base, and a predetermined amount of magnesium silicate having an average particle size of 2 to 10 μm is blended therein. It is possible to significantly improve the damping performance by increasing the tan δ value and reducing the temperature dependence of the elastic modulus while maintaining good mechanical properties. As a result, it is possible to follow the large displacement of laminated rubber with an elongation of 600% or more, and to satisfy the various properties required for high-damping laminated rubber, such as having good mechanical properties and various damping performances. . Moreover, if the vibration damping material obtained in this way is used for laminated rubber, there is no need to use a steel damper in combination with the basic seismic isolation system.

0012

[Example] An example of the present invention will be described.

Examples 1 to 3 Vibration damping materials were produced by blending each component according to the formulations shown in Table 1 and vulcanizing it by a conventional method. Using this, hardness (JIS-A), tensile strength, elongation, ta
n δ value (measured at 23°C, 0.3Hz, DMTA)
, the rate of change in elastic modulus at -10°C and 40°C (-1
Value at 0°C/Value at 40°C), equivalent attenuation constant (
25℃, 0.5Hz vibration sine wave, 100% shear strain)
were measured respectively. These results are shown in the table.

Comparative Examples 1 to 5 As a comparison, one lacking magnesium silicate (Comparative Example 1), one containing an excessive amount of magnesium silicate (Comparative Example 2), and one in which the particle size of magnesium silicate was larger than the specified range. One using 20 μm particle size (Comparative Example 3), one using 1 μm particle size smaller than the specified range (Comparative Example 4), and one using graphite instead of magnesium silicate (Comparative Example Regarding 5), each component was blended and vulcanized in the formulation shown in the table, and tested in the same manner as in Example 1. The results are shown in the table.

[0015]

[Table 1]

[0016]

[Effects of the Invention] As is clear from the above examples, the vibration damping material of the present invention has significantly improved damping performance without impairing the good mechanical properties of natural rubber, and has a high level of performance. It simultaneously satisfies various properties required for damping laminated rubber.

Claims (1)

[Claims] 1. A vibration damping material characterized in that it is made by vulcanizing a composition in which 100 parts by weight of natural rubber is blended with 5 to 100 parts by weight of magnesium silicate having an average particle size of 2 to 10 μm as a filler.