JPH1081794A - Rubber composition for rubber vibration insulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition which has improved roller processability and molding processability and can increase the damping properties by using an ethylene-α-olefin-non-conjugated diene terpolymer (EOR) as a raw rubber material. SOLUTION: This composition comprises, as the base polymers, (A) 50-90wt.% of the rubber components consisting of (i) 30-100wt.% of EOR and 70-0wt.% of (ii) a natural rubber(NR) and (B) 50-10wt.% of an ethylene-α-olefin copolymer resin (PO) of 65-85wt.% of the ethylene content and the component (i) has a viscosity of >=90 (MLH4 100 deg.C) (not oil-extended). Thus, this composition has excellent heat resistance, low viscosity, low dynamic magnification and is suitably useful as a damping rubber material for cars and in industry.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing a rubber material having an EOR.
And a rubber composition for vibration-proof rubber. In particular, the present invention relates to a rubber composition for an anti-vibration rubber, which has good anti-vibration properties and processability, and is suitable as a material for an anti-vibration rubber for automobiles and industries requiring heat resistance.

[0002] In the following description, blending units are weight units unless otherwise specified.

[0003]

2. Description of the Related Art As the performance of automobiles increases, the temperature in an engine room tends to rise more than ever. For this reason, anti-vibration rubbers for automobiles such as engine mounts are required to have higher heat resistance than ever before.

[0004] However, it is difficult to achieve the required heat resistance with a vibration-proof rubber molded from a conventional NR-based rubber composition.

[0005] Therefore, it has been studied to form an anti-vibration rubber with an EOR-based rubber composition having good heat resistance. In the case of the EOR base, increasing the molecular weight is most effective for achieving a predetermined vibration-proof performance.

[0006]

However, when the molecular weight is increased, the viscosity increases and the roll formability and the formability deteriorate.

[0007] In view of the above, the present invention provides a rubber composition based on a high molecular weight EOR, which is capable of improving the roll processability and the formability, as well as improving the vibration isolation performance. It is intended to provide a rubber composition for vibration rubber.

[0008]

Means for Solving the Problems The composition for a vibration-proof rubber of the present invention solves the above-mentioned problems by the following constitutions.

The viscosity (ML _{1 + 4} 100 ° C.) at the time of non-oil extension is 9
A rubber composition for an anti-vibration rubber having EOR of 0 or more as a base polymer, wherein the base polymer is EOR 30 to
Rubber component having a composition of 100 wt% and NR of 70 to 0%: 5
PO component having 0 to 90 wt% and ethylene content of 65 to 85 wt%: 50 to 10 wt%.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments.

(1) The rubber composition for vibration damping rubber has a viscosity (ML _{1 + 4} 100 ° C.) of 90 or more, preferably 13 when not oil-extended.
EOR (ethylene / α-olefin / non-conjugated diene copolymer rubber) of 0 or more, more preferably 200 or more
To be a base polymer.

The upper limit of the viscosity is preferably higher from the viewpoint of vibration isolation performance, but is usually set to 500 or less.

If the viscosity of EOR is too low,
If the OR is not a high molecular weight, it is difficult for the vibration-proof rubber to have a predetermined vibration-proof performance. In particular, when the EOR content is high, the tendency becomes remarkable.

The EOR used in the present invention generally has an ethylene content of 45 to 65%, preferably 50 to 60%. If the ethylene content is too low, a problem tends to occur in the vibration isolation performance, and if the ethylene content is too high, a problem tends to occur in the cold resistance.

Further, as the α-olefin of EOR,
One or more of propylene, 1-butene, 1-hexene and the like are selected and used. Examples of the non-conjugated diene (third component) include ethylidene norbornene, dicyclopentadiene, and the like.
Usually, it is 0.5 to 15%, preferably 4 to 11%. If the third component is too small, it is difficult to obtain a sufficient crosslink density,
On the other hand, if it is excessive, the elongation at break (E _B ) may decrease, and the durability may decrease.

Here, the rubber composition contains a peroxide,
Along with vulcanizing agents such as sulfur, auxiliary materials such as carbon black, process oil, zinc white, stearic acid, and antioxidants are blended.

(2) In the above, the rubber composition of the present invention is characterized in that the rubber component in the base polymer has an EOR of 30 to 10 or less.
0% (preferably 40 to 100%), NR 70 to 0%
(Preferably 60 to 0%).

If the EOR is too small, that is, if the NR is too large, it is difficult to impart heat resistance to the vibration-proof rubber. Also, in order to improve the vibration isolation performance of the vibration isolation rubber, NR 20% or more,
Desirably, the composition is 30% or more.

(3) In addition, the rubber composition of the present invention has an ethylene content of 65 to 65 in addition to the rubber component in the base polymer.
85% (preferably 70-80%) or more of the PO component is blended. The compounding composition is 50 ~~ 90% of rubber component
(Preferably 55-85%), PO component 50-10%
(Preferably 45 to 15%).

The PO component has a function of reducing the viscosity of the base polymer, and thus the composition, and a function of improving the vibration-proofing performance. The reason is presumed to be due to the thermoplastic resin properties of PO and the relative increase in ethylene content in the base polymer.

When the ethylene content of the PO is low, it is difficult to improve the vibration isolating performance. The higher the ethylene content, the better. However, if the ethylene content is too high, the resinity becomes too high, which may adversely affect the cold resistance and the like of the vibration damping rubber.

As the α-olefin which is a comonomer of PO with respect to ethylene, propylene, 1-butene,
1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene having 3 to 10 carbon atoms can be used. In particular, ethylene-octene copolymers having a narrow molecular weight and a uniform comonomer component are desirable. More specifically, the product name "Engage"
Launched by The Dow Chemical Company,
Polyolefin elastomers can be suitably used.

(4) The rubber composition of the present invention can be prepared by a conventional method.
The rubber material is kneaded under the conditions to produce a rubber material, and a vibration-proof rubber is manufactured by known injection molding, press molding or the like.

[0024]

The rubber composition for vibration-isolating rubber according to the present invention comprises, as described above, EOR as a base polymer.
In addition to being excellent in heat resistance, the composition of the present invention has a lower viscosity and a lower dynamic magnification than the conventional example, as shown in Comparative Examples and Examples described later.

Therefore, the rubber composition for vibration-proof rubber of the present invention can improve the roll processability and the formability of a rubber composition based on a high molecular weight EOR, and can prevent the vibration-proof rubber from being improved. Vibration performance can also be improved.

Known publications that disclose related techniques for improving heat resistance, roll workability, and the like are disclosed in JP-A-5-179079 and JP-A-6-25484.13.
No. 6203/200096. The related techniques described in these known publications are different from the present invention in constitution, and do not affect the invention of the present invention.

[0027]

EXAMPLES Examples and comparative examples performed to confirm the effects of the present invention will be described below.

(1) After kneading each composition having the composition shown in Table 1, as a molding material, the viscosity of each molding material was measured.
The measurement was performed according to JIS K 6300.

(2) Each test piece was prepared from each of the above molding materials (vulcanization conditions: 160 ° C. × 10 min), and a test of vibration isolation performance was performed by the following method.

[FT Rheospectrometer-DVE-V]
4 "(manufactured by Rheology Co., Ltd.) and the static elastic modulus (E
_S ) and the dynamic elastic modulus (E'100HZ) (dynamic magnification: E '
/ E _S ).

E _S : σ ₁₀ × 9.15 (where σ ₁₀ is a value obtained by dividing the stress at the time of 10% elongation of a 5 mm strip by the cross-sectional area of the test piece).

E'100HZ: A value measured when a dynamic distortion of ± 0.5% and 100HZ is added to a 5 mm strip in a state of 10% elongation.

(3) Table 1 shows the test results. It can be seen that, in each example, not only the viscosity but also the dynamic magnification, which is an index of the anti-vibration performance, is lower than the corresponding comparative example.

[0034]

[Table 1]

* 1) Ethylene content: 56 wt%, third component (ethylidene norbornene): 6%, process oil 7
Viscosity at 0 phr content (ML _{1 + 4} 120 ° C) 63 (Note: clay when not oil-extended (ML _{1 + 4} 100 ° C) about 300) * 2) “Engage” (ethylene / octene copolymer: ethylene content) 75%)

Claims (2)

[Claims] An ethylene / α-olefin / nonconjugated diene copolymer rubber (abbreviated as “EOR”) having a viscosity (ML _{1 + 4 at} 100 ° C.) of 90 or more when not oil-extended is used as a base polymer. A rubber composition for an anti-vibration rubber, wherein said base polymer is 30 to 100% by weight of said EOR and 70 to 70% of natural rubber (NR)
Rubber component having a composition of 0 wt%: 50 to 90 wt%, ethylene / α-olefin copolymer resin (hereinafter abbreviated as “PO”) component having an ethylene content of 65 to 85 wt%: 50 to 90 wt%
A rubber composition for a vibration-proof rubber, comprising 10% by weight. 2. The rubber composition according to claim 1, wherein the PO is an ethylene-octene copolymer.