JP2001164044A - Vibration insulating rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration insulating rubber composition having extremely good damping characteristics. SOLUTION: This vibration insulating rubber composition is obtained by compounding 100 pts.wt. at least one kind of rubber selected from a natural rubber and a synthetic dienic rubber, with 30-100 pts.wt. carbon black having 100-160 m2/g specific area measured by nitrogen adsorption (N2SA), 100-150 m2/g specific surface area measured by CTAB absorption (CTAB), 90-140 ml/100 g DBP absorption (DBP) and 5-30 ml/100 g ΔDBP (24M4DBP-DBP) as characteristics of the carbon black.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-damping seismic isolation rubber composition having a damping property in a rubber material itself and suitable for seismic isolation / vibration isolation, absorption of vibration energy, and the like.

[0002]

2. Description of the Related Art In recent years, in the construction industry and the like, seismic isolation technology using laminated rubber has attracted attention as a technology for protecting a building and equipment inside the building from an earthquake disaster. In general, seismic isolation means vibration isolation against seismic motion. Specifically, a method is employed in which a building is supported by laminated rubber to give a long natural period of the building, thereby reducing the seismic response.

[0003] Conventionally, rubber compositions used in such applications have been prepared by adding resins, softeners and the like in order to impart high damping characteristics. However, when these resins and softeners are blended, there is a problem that the creep characteristics are greatly deteriorated, and the temperature dependency, the breaking characteristics, and the like are often deteriorated.

Japanese Patent Application Laid-Open No. 10-324777 discloses a rubber component 1 comprising a polyisoprene rubber having 1,4-bonded isoprene and a butadiene rubber having cis 1,4-bonded.
For 100 parts by weight, 20 to 100 parts by weight of a liquid polyisoprene rubber having 1,4-bonds of isoprene is compounded,
For 100 parts by weight of this rubber component, the nitrogen adsorption specific surface area (N ₂ SA) is 50 to 100 m ² / g, and the dibutyl phthalate oil absorption (DBP) is 50 to 250 ml.
A high-damping seismic isolation rubber composition containing 30 to 100 parts by weight of carbon black which results in a rubber composition of 100 g / 100 g is described, but the rubber composition is extremely limited.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a seismic isolation rubber composition which exhibits excellent damping characteristics even with natural rubber or the like by blending carbon black having specific properties. Things.

[0006]

The present inventors have conducted various studies on the relationship between the damping characteristics of seismic isolation rubber and carbon black, and found that the aggregate size distribution, the nitrogen adsorption specific surface area N
₂ By blending carbon black having a specific range of SA, CTAB adsorption specific surface area and DBP oil absorption property,
We found that the damping characteristics of seismic isolation rubber improved significantly.

The present invention has been completed on the basis of such findings, and a nitrogen adsorption specific surface area (N ₂ SA) as a characteristic of carbon black is contained in 100 parts by weight of at least one kind of natural rubber or diene-based synthetic rubber. 100m ² / g
Over 160 m ² / g, CTAB adsorption specific surface area (C
TAB) is more than 100m ² / g less than 150m ² / g,
DBP absorption (DBP) exceeds 90ml / 100g and 1
Less than 40 ml / 100 g, ΔDBP (24M4DBP-
DBP) exceeds 5ml / 100g and 30ml / 100g
Less than 50 to 100 parts by weight of carbon black.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The seismic isolation rubber composition of the present invention is obtained by dispersing components such as carbon black having a specific property and, if necessary, a petroleum resin in a rubber matrix. This rubber composition is produced by blending carbon black, a petroleum resin, a vulcanizing agent, and other auxiliary materials with an unvulcanized rubber and vulcanizing it.

Hereinafter, each component will be described. Rubber In the present invention, as the rubber, in addition to natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene / butadiene copolymer rubber (SBR), acrylonitrile / butadiene copolymer rubber (NBR), butyl rubber ( IIR), halogenated butyl rubber (Br-IIR, C
Various diene-based synthetic rubbers such as 1-IIR) and chloroprene rubber (CR). Above all, NR and IR are preferably used because they have a good balance of attenuation and workability. Further, two or more diene rubbers may be used in combination.

Carbon black The carbon black to be added to the rubber composition of the present invention has a nitrogen adsorption specific surface area (N ₂ SA) of more than 100 m ² / g and
Less than 60 m ² / g, CTAB adsorption specific surface area (CTAB)
140ml exceeded but 100 m ² / g, greater than 150m ² / g, DBP absorption (DBP) is a 90 ml / 100 g
/ Less than 100g, ΔDBP (24M4DBP-DBP)
Is more than 5 ml / 100 g and less than 30 ml / 100 g.

The colloidal physical properties of the carbon black compounded in the present invention are the most important, and the specified requirements and the significance of the limited range are as follows.

(1) Nitrogen adsorption specific surface area (N ₂ SA), which is one of the basic characteristics of carbon black, is 100 m ² / g.
Over 160 m ² / g. In general, it is desirable that the specific surface area of the high damping rubber composition is high. However, when the N ₂ SA value is 160 m ² / g or more, which is the upper limit, the dispersibility of carbon black in the rubber matrix is reduced, and the processability is also significantly reduced. In addition, if it is less than 100 m ² / g, it may not be possible to obtain a desired damping property. A more preferred N ₂ SA range is from 120 to 150 m ² / g of carbon black.

[0013] (2) a CTAB adsorption specific surface area is a method of assessing another carbon black surface area range of the present invention is less than 150 meters ² / g exceed 100 m ² / g. The disadvantages outside this range are the same as for N ₂ SA. A more preferred CTAB range is 110-14.
0 m ² / g.

(3) The DBP absorption (an index of the degree of connection (structure) of the carbon black constituent unit particles), which is another basic property, is improved by increasing the structure to improve the dispersibility in the rubber matrix. However, if it is raised too much, the elongation property, which is one of the important properties of the seismic isolation rubber, is reduced, and the workability during kneading is reduced. Also, if too low elasticity modulus is lowered, the spring characteristics can not be sufficiently DBP absorption characteristics exceed ^{90m 2} / 100g 140m 2 / 100g
Less than the range. A more preferable range is 95 to 135 m.
^It has a 2/100 g characteristic.

(4) The amount of 24M4DBP absorption (24M4) measured to evaluate the structure of carbon black after being kneaded in rubber and the aforementioned DB
Difference from P absorption (DBP absorption−24M4 = ΔDBP)
Is more than 5 ml / 100 g and in the range of 30 ml / 100 g in the present invention.

The ΔDBP value of the above characteristic is 24000 psi
Difference between the DBP absorption amount (24M4) and the DBP absorption amount (DBP-24M
4 = ΔDBP) and more than 3 ml / 100 g, that is, the ratio of the fragile structure in the structure characteristics is large, and the structure is broken at the time of kneading with rubber, so that sufficient strength cannot be obtained. . If the value is 5 or less, the initial torque at the time of rubber kneading does not increase and the dispersibility decreases, so this value is set to the above specific range.

(5) In addition to the above characteristics, aggregate characteristics, that is, a weight average diameter (Aw, nm) of the aggregate calculated from a histogram indicating the measured value of each aggregate by centrifugal sedimentation analysis and the frequency thereof, Number average amount (A
n, nm), and the value of Aw / An are limited to 1.10 to 1.50, which is a smaller range than in the related art.

In the above characteristics, when the value of Aw / An exceeds 1.50, it means that the distribution of the aggregate is wide, and therefore, it is impossible to impart a sufficient damping property to the rubber composition. Carbon black having a small numerical value is preferable because it gives good damping properties, but it is difficult to achieve 1.10 or less in the current production process, so
The numerical range is 1.50.

(6) In addition to the above characteristics, one of the features is that the amount of surface functional groups present on the surface of carbon black is lower than that of conventional carbon black, and the weight loss ratio on the low temperature side is small.

The feature that the amount of surface functional groups present on the surface of carbon black is lower than that of conventional carbon black is defined in relation to the surface activity and processability of carbon black. 105 ° C to 900
Loss on heating (VS) per unit area up to ℃ 0.11
When it exceeds mg / m ² , the surface activity of carbon black increases, the loss performance at the polymer interface decreases,
High attenuation characteristics cannot be maintained. Further, the increase in the amount of surface functional groups causes the carbon black to react with the polymer before kneading in the rubber matrix during rubber kneading, which causes a reduction in processability, so that the above range is set.

(7) Further, it is necessary that the heating loss on the low-temperature side is smaller than that on the high-temperature side in the ratio during the entire heating loss.

This is because the surface functional groups which are generated and reduced on the low temperature side have high activity, and therefore have high reactivity with the polymer. By setting the ratio to 0.6 or less, the loss characteristics between the carbon black and the polymer can be increased, and the processability can be improved.

(8) The specific coloring power of carbon black due to various characteristics such as the particle size and distribution, the structure size, and the aggregate size and distribution is more than 115% and less than 130%. Is required in the present invention. The value of less than 130% of the upper limit of the specific coloring power is lower than the conventional value when viewed from the range where the upper limit of the specific surface area is less than 160 m ² / g, and is one of the features of the present invention.

In the present invention, as described above, the aggregate distribution is on the narrow side, and the coloring power is originally in the direction of increasing. However, the specific coloring power is reduced due to another important requirement, low surface activity, so the upper limit is less than 130%.

If this value is less than the lower limit of 115%, the elastic modulus is reduced, so that the present invention provides good rubber properties.

In the present invention, a high-attenuation rubber composition can be obtained by compounding carbon black into a rubber matrix. Other rubber compounding agents, for example, fillers other than carbon black, vulcanizing agents, vulcanization accelerators Alternatively, it goes without saying that other polymer material components and the like can be appropriately blended.

The properties of the carbon black according to the present invention are measured by the following methods.

(I) Specific surface area of nitrogen adsorption (N ₂ SA) Specific surface area per unit weight, m ² / g, measured according to the method described in Method D of Section 7 of JIS K6217: 1997.
Is displayed with.

(Ii) CTAB adsorption specific surface area (CTAB) Measured according to the method described in Section 8 of JIS K6217: 1997, and expressed as CTAB adsorption specific surface area per unit weight, m ² / g.

(Iii) DBP absorption amount Measured according to the method described in Section 9A of JIS K6217: 1997 and expressed in ml of dibutyl phthalate (DBP) absorbed per 100 g of carbon black.

(Iv) 24M4DBP absorption amount Measured according to the method described in JIS K6217: 1997, paragraph 10, and expressed in ml of dibutyl phthalate (DBP) absorbed per 100 g of carbon black.

(V) Specific Coloring Power The light reflectance (S) of the sample with respect to the light reflectance (R) of the standard carbon black for specific coloring power measurement, which is measured by the method described in Section 11 of JIS K6217: 1997. Is displayed as a relative ratio (T = 100 R / S) (%).

(Vi) Method for analyzing carbon black aggregate size by centrifugal sedimentation analysis Measuring apparatus: high-speed disk centrifugal ultra-particle size analyzer (measurement apparatus name: BI-DCP, BROOKHAVEN INSTRUMENTS CORP)
ORATION) Measurement method: A carbon black sample dried according to JIS K6218 is used in a small amount of a surfactant (Nonidet P).
-40), kneaded well to form a paste, and then mixed with a 20% by volume aqueous ethanol solution to obtain a carbon black concentration of 2%.
A dispersion of 00 mg / l is prepared and sufficiently dispersed with an ultrasonic homogenizer to prepare a sample.

The rotation speed of the apparatus was set to 8,000 rpm, 10.0 ml of spin solution (pure water, 24 ° C.) was added, and then 1.0 ml of buffer solution (20% by volume ethanol aqueous solution, 24 ° C.) was injected. I do. Next, 0.5 ml of a carbon black dispersion at 24 ° C. is injected to start the measurement.

The Stokes-equivalent diameter corresponding to each time t is calculated from the distribution curve of the elapsed time and the absorbance after the addition of the carbon black dispersion liquid by the formula (1).

[0036]

(Equation 1)

In Equation 1, η is the viscosity of the solvent (mPa ·
s), ω is the disk rotation speed (rpm), Δρ is the density difference between the carbon black particles and the solvent (g / m ³ ), Ri is the radius (cm) of the injection point of the carbon black dispersion, and Rd is the distance to the absorbance measurement point. Radius (cm) and t is time (minute).

Definition of weight-average diameter (Aw) and number-average diameter (An) of the aggregate system: The distribution curve is divided equally into 40 parts between the minimum Stokes diameter and the maximum Stokes diameter, and the central value of each histogram is obtained. Is Di, and the frequency is Ni, and the values of Aw and An are calculated by the following equations.

[0039]

(Equation 2)

[0040]

(Equation 3)

The value of Aw / An is characterized in that this value increases when the aggregate diameter distribution is wide, particularly when there is an aggregate diameter on the larger side, and is a measure for evaluating the breadth of the distribution. Used as one of the.

(Vii) Evaluation of surface functional group content by thermogravimetry Measurement equipment used: Thermogravimetric analyzer TGA-50 (manufactured by Shimadzu Corporation) Measurement atmosphere: nitrogen atmosphere 50 ml / min Measurement sensitivity: ± ω20 mg Measurement method ... Approximately 18 mg of sample carbon black is placed in a platinum cell, and the weight is precisely weighed to the nearest 0.1 mg (W
g). The platinum cell containing the carbon black is set in a thermogravimeter, heated from room temperature to 105 ° C. at a rate of 10 ° C./min, kept at this temperature for 60 minutes, and the value is read (Wb). After the holding, the temperature of the measuring device is raised to 920 ° C. at a temperature of 15 ° C./min.

The weight (W _L ) reduced by heating from 105 ° C. to 450 ° C. and the weight (W _H ) reduced by heating from 450 ° C. to 900 ° C. were measured, and V _L ,
Calculate _VH , VS, and the heating loss ratio ( _VL / _VH ).

[0044]

(Equation 4)

Here, A is N _{2 of the} sample carbon black.
SA (m ² / g).

Petroleum Resin The rubber composition of the present invention preferably contains a petroleum resin. This petroleum resin includes coumarone, indene, styrene, and other coumarone plastics contained in solvent naphtha, and cracking produced as a by-product from an ethylene plant that produces ethylene, propylene, etc. by steam cracking petroleum. Examples include resins obtained by polymerizing diolefins and monoolefins contained in the oil fraction without isolating them.

The petroleum resin is added to the rubber composition of the present invention in an amount of 15 to 60 parts by weight, preferably 25 to 55 parts by weight, based on 100 parts by weight of the total amount of rubber. If less than 15 parts by weight,
If the damping property is insufficient, and if it is 60 parts by weight or more, the creep property increases, which is not preferable.

Optional Components In producing the vulcanized rubber composition of the present invention, an unvulcanized rubber may be blended with aroma oil, rosin, etc. in addition to the above essential components. Naturally, a vulcanizing agent such as sulfur, a vulcanizing aid such as zinc white and stearic acid, an antioxidant and the like are appropriately blended.

The unvulcanized rubber composition containing these compounding agents is appropriately molded and vulcanized at, for example, 120 to 160 ° C. using a method and a device known per se to obtain a vulcanized rubber composition. Can be

This seismic isolation rubber composition has a frequency of 0.2 Hz and 10 Hz.
The equivalent damping constant (h _eq ) at 0% strain is preferably 0.18 or more. The shear elastic modulus (G) at 0.2 Hz and 100% strain is 8 to 8 for the seismic isolation rubber composition for bridges.
16 (kgf / cm ² ), and preferably 3 to 8 as a building seismic isolation rubber composition.

The rubber composition of the present invention and hard plates made of, for example, steel plates for general structure and cold rolled steel plates are alternately laminated to form a seismic isolation laminate. To produce this laminate, after molding and vulcanization to obtain a sheet-like rubber composition,
It may be bonded to the hard plate with an adhesive, or it may be manufactured by forming an unvulcanized rubber compound into a sheet in advance, laminating it on the hard plate, and then heating and simultaneously vulcanizing and bonding. Can also. Such a seismic isolation laminate can be suitably used, for example, for the support of a road bridge or the basic seismic isolation of a building.

[0052]

EXAMPLES Examples and comparative examples will be described below.

In the proportions shown in Table 2, natural rubber (NR), petroleum resin, carbon black, sulfur, vulcanization accelerator CZ and, if necessary, aroma oil and rosin were blended. This compound was vulcanized at 145 ° C. for 45 minutes to obtain a seismic isolation rubber composition.

The carbon blacks used in the examples and comparative examples are carbon black A and carbon black B having the characteristics shown in Table 1 below.

[0055]

[Table 1]

The obtained vulcanized rubber has a shear elasticity
Number (G) and vibration absorption properties (h_eq) And measure as
did. The results are shown in Table 2. Test conditions (1) Test machine name; spring stiffness, loss energy measurement device
(Model EFH-20-8-10, manufactured by Washinomiya Seisakusho) (2) Shearing 100% at the frequency of 0.2 Hz (first time) 3 times
Shear → 200% 3 times shear → 100% (second time) 3 times shear
The test was repeated in the direction of the arrow, and the first test was 100%
Of the third and second 100% data
Leveling, equivalent spring rigidity G (kgf / cm²) And equivalent damping
Constant h_eqAsk for. G is usually kgf / cm²so
Although expressed in terms of Si units, the conversion is as follows. 1kgf / cm²= 9.8 × 10⁴Pa The following characteristics (1) to (5) were also measured. The results are shown in Table 2.
Shown. JIS A hardness (Hs) Measured according to JIS K6301. Elongation (E_B) Measured according to JIS K6301. Tensile strength (T_B) Measured according to JIS K6301. 100% modulus M₁₀₀  300% modulus M₃₀₀

[0057]

[Table 2]

[0058]

As described above, according to the present invention, a seismic isolation rubber composition having extremely excellent damping characteristics is provided. This seismic isolation rubber composition has high elongation and breaking strength, and also has a good shear modulus G.

Claims (10)

[Claims] 1. A nitrogen adsorption specific surface area (N ₂ SA) of 100 m ² as a characteristic of carbon black is added to 100 parts by weight of at least one kind of natural rubber or diene-based synthetic rubber.
/ G, greater 160m less than ² / g, CTAB adsorption specific surface area (CTAB) exceeds the 100 m ² / g 150 meters ² / less than g, DBP absorption amount (DBP) of less than 140 ml / 100 g exceed 90ml / 100g, ΔDBP (24M4DB
P-DBP) exceeds 5 ml / 100 g and 30 ml / 10
A seismic isolation rubber composition containing 30 to 100 parts by weight of carbon black of less than 0 g. 2. The seismic isolation rubber composition according to claim 1, wherein the compounding amount of carbon black is 50 to 90 parts by weight. 3. The carbon black according to claim 1, wherein the specific coloring power (TINT) of the carbon black is more than 115% and 130%.
% Of the base-isolated rubber composition. 4. The carbon black according to claim 1, wherein the carbon black has a weight average diameter (Aw) and a number average diameter (An) corresponding to an aggregate stalk in an aggregate characteristic by centrifugal sedimentation analysis. Aw / An is 1.
The rubber composition having a ratio of 10 to 1.50. 5. The carbon black according to claim 1, wherein the carbon black has a heating loss (VS) per unit area from 105 ° C. to 900 ° C. of 0.11 mg / m 2.
^A rubber composition having a seismic isolation of ² or less. 6. A any one of claims 1 to 5, weight loss on heating from 105 ° C. The carbon black to 450 ° C. _(V L) heat loss from (wt%) and 450 ° C. to 900 ° C. _{(V H} ) (Weight%), and the ratio V _L / V _H is 0.6 or less. 7. The seismic isolation rubber composition according to claim 1, wherein the equivalent damping constant (h _eq ) at 0.2 Hz and 100% strain is 0.18 or more. . 8. A seismic isolation rubber composition for a bridge according to any one of claims 1 to 7, wherein the shear modulus (G) at 0.2 Hz and 100% strain is 8 to 16. . 9. The seismic isolation rubber composition according to any one of claims 1 to 7, wherein the shear modulus (G) at 0.2 Hz and 100% strain is 3 to 8. . 10. A seismic isolation rubber composition according to claim 1, wherein 15 to 60 parts by weight of a petroleum resin is blended.