JPH03177441A - High-damping rubber composition - Google Patents

Abstract

PURPOSE:To obtain the subject high-damping rubber composition excellent in loss properties, failure characteristics, temperature dependence, etc., and suitable for a vibration-proofing equipment, a vibration-deadening equipment, etc., by blending rubber with a specified resin and carbon black in mutually specified amount. CONSTITUTION:With (A) 100 pts.wt. rubber mainly composed of natural rubber, (B) 15-60 pts.wt. thermoplastic hydrocarbon-based resin composed of a (co)polymer of 9C-based aromatic unsaturated hydrocarbon (e.g. alpha-methylstyrene or 0-vinyltoluene) and/or a copolymer of a 9C-based aromatic unsaturated hydrocarbon and a 5C-based aliphatic unsaturated hydrocarbon (e.g. pentene-1 or pentene-2) and (C) 40-80 pts.wt. carbon black having 70-110m<2>/g surface area by the nitrogen adsorption method, 60-90ml/100g DBP oil absorption, 75-105nm most probable value of aggregate distribution and 65-85nm the width of the distribution are blended.

Description

Detailed Description of the Invention <Field of Industrial Application> The present invention relates to a highly attenuated rubber composition, particularly for vibration isolation and damping of automobiles, various machines, etc. The present invention relates to a rubber composition having high damping properties suitable for use in vibration energy transmission and absorption devices.

<Prior art> In recent years, vibration energy absorption devices such as vibration isolation, vibration isolation,
Seismic isolation devices are rapidly becoming popular. One form of such an absorption device is a laminated type seismic isolation rubber device (seismic isolation laminate 1) shown in Fig. 1, which has a large seismic isolation effect and is suitable as a rubber layer of a seismic isolation rubber device. A rubber material that also has a damping effect is strongly desired.

In FIG. 1, 2 is a rubber layer, and 3 is a hard plate such as a steel plate.

By the way, conventionally, in order to give a rubber material high damping properties, that is, to obtain a rubber composition that exhibits high damping properties after vulcanization, a method of blending a large amount of carbon black, a method of blending a large amount of carbon black, a method of blending a large amount of carbon black, and a method of blending a large amount of carbon black, A method using a polymer with a high
A method of blending a large amount of a specific resin as disclosed in the above publication has been proposed.

However, when a large amount of 4-bon black is blended, although it does result in high hysteresis loss after vulcanization, it has the major drawback of reducing elongation, which is another important property.

In addition, when a polymer with a high Tg is used, after vulcanization, it exhibits high hysteresis loss characteristics in a relatively high temperature range above room temperature, but in the low temperature range, which is the practical temperature range, the elastic modulus becomes high and the It has the disadvantage of reduced elongation.

On the other hand, if a large amount of a specific resin such as a softener is blended, high hysteresis loss and large elongation at break will occur after vulcanization, but this will have the disadvantage of significantly deteriorating breaking strength and set resistance. .

As described above, at present, no rubber composition has been proposed that provides a rubber material that exhibits high hysteresis loss characteristics in a practical temperature range, has high elongation at break, and has good strength at break.

The term "rubber material" is used to refer to a vulcanized rubber composition.

<Problems to be Solved by the Invention> The present invention was made in view of one or more of the above circumstances, and it has a large hysteresis loss, a large elongation at break, and a temperature dependence of the elastic modulus in a practical temperature range. It is an object of the present invention to provide a high damping rubber composition which provides a rubber material having a small amount of rupture and a high breaking strength.

Means for Solving the Problems> The present invention provides a rubber whose main component is natural rubber, and the rubber 10.
0 [For Oki part, (co)polymer of C9 aromatic unsaturated hydrocarbon and/or C9 aromatic unsaturated hydrocarbon and C
15 to 60 parts by weight of thermoplastic hydrocarbon resin, which is a copolymer with S-based aliphatic unsaturated hydrocarbon, nitrogen adsorption specific surface area of 70 to 110 m'', 7 g% DBP oil absorption of 60 to 90
mj! / 100 g% aggregate distribution mode (O
S t ) is 75 to 1105n, and its distribution width (Δ0-1
) is 65 to 85 nm carbon black 40 to 80
The present invention provides a high damping rubber composition characterized by containing 11 parts by weight.

The present invention will be explained in detail below.

The rubber component of the rubber composition of the present invention is mainly composed of natural rubber. Therefore, in addition to natural rubber, BR,
It may contain NBR, butyl rubber, halogenated butyl rubber, chloroprene rubber, etc. The proportion of natural rubber in the rubber component is preferably 6031i% by weight or more.

The thermoplastic hydrocarbon resin used in the rubber composition of the present invention is
(Co) of C8 aromatic unsaturated hydrocarbons! ! Polymer/
Alternatively, it is a copolymer of a C@-based aromatic unsaturated hydrocarbon and a C3-based aliphatic unsaturated hydrocarbon.

C, aromatic unsaturated hydrocarbons include α-methylstyrene, O-vinyltoluene, m-vinyltoluene, p-
Examples include vinyl-substituted aromatic hydrocarbons such as vinyltoluene.

In addition, C copolymerized with 0 g of aromatic unsaturated hydrocarbons
Examples of S-based aliphatic unsaturated hydrocarbons include pentene-(1) contained in the C6 fraction obtained by thermal decomposition of naphtha.
, pentene-(2), 2-methylbutene-(1), 3-
Olefinic hydrocarbons such as methylbutene-(1) and 2-methylbutene-(2), and 2-methylbutadiene-(1)
,3) Pentagene-(1゜2), Pentagene-
(1,3), diolefin hydrocarbons such as 3-methylbutadiene-(1,2), and the like.

These can be polymerized or copolymerized by Friedel-Krach reaction or the like in the presence of a suitable catalyst. And (co) of C1-based aromatic unsaturated hydrocarbons! ! The polymers include Hi-Resin R3-9 and Hi-Resin R3-21 (
Copolymers of 0g aromatic unsaturated hydrocarbons and Cs aliphatic unsaturated hydrocarbons include HiResin #90 and HiResin QP.
A (all manufactured by Toho Chemical Industries, Ltd.), etc.

In addition, here, (co) of C9 aromatic unsaturated hydrocarbon
The polymer refers to either a polymer of 09 type aromatic unsaturated hydrocarbons or a copolymer of two or more 09 type aromatic unsaturated hydrocarbons.

Further, the copolymer of a 0g aromatic unsaturated hydrocarbon and a C6 aliphatic unsaturated hydrocarbon preferably has a C, aromatic unsaturated hydrocarbon unit of 60 mol% or more, More preferably, C is 90 mol% or more.
As the number of tertiary aliphatic unsaturated hydrocarbon units increases, the softening point of the copolymer tends to decrease.

Furthermore, the thermoplastic hydrocarbon resin used in the present invention has a softening point (JIS K2207 > 50 to 150°C) and a bromine number ( JIS K2543) is 1
Preferably, it is within the range of 5 to 60 Br-g/100g; those with a low softening point are not easy to use.

The rubber composition of the present invention comprises rubber 1 containing natural rubber as a main component.
00 parts by weight, 15 to 60 parts of thermoplastic hydrocarbon resin
Contains parts by weight. When the thermoplastic hydrocarbon resin is less than 15 parts by weight, the loss tangent (hereinafter referred to as tan δ) of the rubber material decreases and the elongation at break becomes insufficient.

On the other hand, if it exceeds 60 parts by weight, the breaking strength of the rubber material decreases, and at the same time, the temperature dependence of the elastic modulus becomes too high.

The carbon black used in the rubber composition of the present invention has a nitrogen adsorption specific surface area of 70 to 110 m'/g% and an oil absorption amount of DBP (dibutyl phthalate) of 60 to 90 mfL/100 g.
, the mode (D, t) of Wi aggregate distribution is 75 to 1105
The distribution width (Δ0 *1) of n, lj aggregate distribution is 65 to 85
nm.

Since the physical properties of carbon black have a large effect on the damping characteristics of the rubber material, the present invention uses carbon black that meets the above conditions.

If the nitrogen adsorption specific surface area (NSA) is less than 70 m'/g, the rubber material will not exhibit sufficient hysteresis loss.
On the other hand, if it exceeds 110 m'/g, the dispersibility of the rubber composition deteriorates and the elongation at break of the rubber material decreases.

A smaller DBP oil absorption amount is advantageous in terms of hysteresis loss and elongation at break of the rubber material, but if it is too small,
This is a problem because the dispersibility in the rubber composition becomes poor. On the other hand, if it exceeds 90 mJ2/100 g, the hysteresis loss and elongation at break of the rubber material will be insufficient. therefore,
60-90 mj! / 100 g is good.

If the mode of aggregate distribution (D gt) is less than 75 nm, the hysteresis loss of the rubber material will increase, but the dispersibility in the rubber composition will deteriorate; on the other hand, if it exceeds 1105 nm,
High hysteresis loss cannot be obtained.

If the distribution width (Δo mt) of the aggregate distribution is less than 65 nm, the elongation at break of the rubber material decreases, while if it exceeds 85 nm, the hysteresis loss of the rubber material decreases, which is not preferable.

The rubber composition of the present invention comprises rubber 1 containing natural rubber as a main component.
00 parts by weight, the above carbon black is added in an amount of 40 to 80 parts by weight.
Contains parts by weight. If it is less than 40 parts by weight, the hysteresis loss of the rubber material will decrease, while if it exceeds 80 parts by weight, the elongation at break of the rubber material will decrease and at the same time the elastic modulus will become too high.

The high damping rubber composition of the present invention contains the components described above, but may also contain, if necessary, a vulcanizing agent such as sulfur, a vulcanization accelerator, a vulcanization accelerating aid, It may also contain anti-aging agents, softeners, fillers and the like.

The rubber material obtained by vulcanizing the rubber composition of the present invention generally has the following characteristics:
Elongation at break (JIS 6301) is 700% or more, tensile strength (JIS K6301) 150k
gf/cm' or more, tan δ (at 30°C) is 0.2 or more, hysteresis loss (at 100% elongation deformation, at
25℃) is 30% or more, storage modulus ratio (E' (-
10°C)/E' (301)] is 3.5 or less.

<Example> EXAMPLES The present invention will be specifically explained below with reference to Examples.

(Example) A rubber composition whose formulation is shown in Table 1 was prepared and heated to 148°C.
Press vulcanization was performed for 30 minutes to obtain a vulcanized rubber (rubber material).The various physical properties of the rubber were measured using the methods described below, and the results are shown in Table 1.

The physical properties of the carbon black used are shown in Table 2, and the methods for measuring each physical property are described below.

From Table 1, the following matters became clear.

■Regarding the thermoplastic hydrocarbon resin Comparative Examples 1 to 3 and Examples 1 to 6 are those in which the thermoplastic hydrocarbon resin was varied.

When the amount of the resin is less than 15 parts by weight, the elongation at break is extremely small and the tan δ is small.

On the other hand, 60! If the amount exceeds 1 part, the elongation at break is large and the loss properties are excellent, but the tensile strength is low and the temperature dependence of the elastic modulus becomes too large.

Comparative Example 6 is an example in which aromatic oil was used instead of thermoplastic hydrocarbon S4 fat.

As is clear from a comparison of Examples 1 to 6 and Comparative Example 6, when the conventionally used aromatic oil was replaced with a thermoplastic hydrocarbon resin, the elongation at break, tensile strength, tan δ, and hysteresis loss were significantly improved. Improved.

(2) Regarding carbon black, Comparative Example 4.5 and Example 2.7.8.9 were obtained by changing the carbon black (CB1) used in the present invention.

When the amount of carbon black is less than 40 parts by weight, t
An δ and hysteresis loss become small, and sufficient loss properties cannot be obtained. On the other hand, if it exceeds 80 parts by weight, loss properties are improved, but elongation at break becomes small.

Comparative Example 7 is an example in which SRF grade carbon black was used instead of carbon black (CBI) having the physical properties specified in the present invention.

As is clear from a comparison between Example 2 and Comparative Example 7, when CBI is used as carbon black, tan δ and hysteresis loss are significantly improved while elongation at break is maintained. In other words, it is clear that the CBI is extremely superior to the conventionally used SRF grade carbon black.

■Regarding rubber Comparative example 8 is an example in which SBR was used alone instead of using rubber whose main component was natural rubber.

As is clear from comparing Example 2 and Comparative Example 8, S
If BR is used, the temperature dependence of the elastic modulus becomes too large.

* 1 * 2 * 3 * 4 * 5 * 6 Nipol 5BR15021, Nippon Zeon ■Nfpo
l BR1220, Zeon High Resin QPA,
Toho Chemical Industry■ Softening point 120℃, Bromine number 25 Br-g/100g High register: /R5-21, Toho Chemical Industry ■Softening point 12
0°C, Bromine number 20 Br”g/100g N-(1,3-dimethylbutyl)-N'-phenyl-P
-Phenylenediamine N-cyclohexyl-2-benzothiazylsulfenamide (A) Method for measuring physical properties of vulcanized rubber (a) Elongation at break) Measured according to JIS K 6301. The higher the number, the greater the growth.

(b) Tensile strength (kgf/cm2) Measured according to JIS K 6301. The larger the number, the greater the strength.

(() tan δ Using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho, 30
Measurement was carried out in an atmosphere of .degree. C. under conditions of a shear strain of 25% and a frequency of 5 Hz.

(d) Hysteresis loss (96) Pulled at a speed of 200 mm/min in an atmosphere of 25°C, i
It was determined from the stress-strain curve at the time of oo% elongation deformation.

(e) Ratio of elastic modulus E' In the same manner as in (c) above, but in an atmosphere of -10°C.
and 30°C, and the elastic modulus (E' (-
10°C) and E'(30°C>) and calculated their ratio.

Table (B) Method for measuring the characteristic values of carbon black (a) Nitrogen adsorption specific surface area (N2 SA) ASTM-03037-7
85 standard methods of testi
ng Carbon Black-5surface A
rea by Nitrogen Adsorption
Measured according to Method C.

(b) DBP oil absorption measured according to JIS K 6221 (1982) ``Test method for carbon black for rubber'' 6.1.2 (1) A method.

(C) Mode of aggregate distribution (Dst1) and distribution width (
ΔD, t) Disccentrifuge (UK JoiceLoeb
1), and was measured by the following method.

Weigh carbon black accurately, add 20% by volume ethanol aqueous solution and surfactant, and make carbon black concentration 5.
Prepare a sample solution by sufficiently dispersing it with ultrasonic waves so that the concentration is 7100 mJZ.

Next, increase the rotation speed of the disk centrifuge to 8000
rpm, and after adding 10 mJ2 of spin liquid (distilled water) to this disc centrifuge, 0.5 mJ
Z buffer i & (20% ethanol aqueous solution)
inject.

Next, 0.5 to 1.0 mJ2 of the sample solution is added to this using a syringe, centrifugal sedimentation is started, and an aggregate distribution curve calculated in terms of Stokes' diameter is created by a photoprecipitation method. The Stokes diameter at the most frequent frequency (peak) in the histogram is set as the mode (D, t), and the most frequent 172
The distribution value of the aggregate when
).

<Effects of the Invention> As explained above, the high damping rubber composition of the present invention is a rubber whose main component is natural rubber, and a specific amount of a specific resin and a specific carbon black are blended into the rubber. The rubber material after composition vulcanization has loss properties (large tan δ, hysteresis loss), fracture properties (large elongation at break,
(high breaking strength) and temperature dependence (low temperature dependence of elastic modulus in the practical temperature range).

Therefore, it is extremely suitable for use in fields where the purpose is to absorb vibration energy, such as for use in vibration isolators, seismic isolation devices, and seismic isolation structures.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a seismic isolation laminate. Explanation of symbols 1... Seismic isolation laminate, 2...Rubber layer, 3...Hard board

Claims (1)

[Claims] (1) Rubber whose main component is natural rubber and C_9 aromatic unsaturated hydrocarbon based on 100 parts by weight of the rubber.
Polymer and/or C_9 aromatic unsaturated hydrocarbon and C
15 to 60 parts by weight of a thermoplastic hydrocarbon resin that is a copolymer with a _5 type aliphatic unsaturated hydrocarbon, a nitrogen adsorption specific surface area of 70 to 110 m^2/g, and a DBP oil absorption of 60 to 9.
0ml/100g, mode of aggregate distribution (D_s_t)
is 75 to 105 nm, and its distribution width (ΔD_s_t) is 6
A high damping rubber composition comprising 40 to 80 parts by weight of carbon black having a particle size of 5 to 85 nm.