JPH0721094B2 - Method for producing rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an ethylene / α-olefin / non-conjugated diene copolymer rubber and / or butyl rubber composition. More specifically, an ethylene / α-olefin / non-conjugated diene copolymer rubber and / or butyl rubber composition having excellent heat resistance, excellent fatigue resistance not only in a normal temperature atmosphere but also in a high temperature atmosphere, and a low dynamic ratio. It is about things. The rubber composition of the present invention can be optimally used, for example, as an anti-vibration rubber having excellent durability for automobiles and industries.

<Prior Art> Generally, transportation means such as automobiles and motorcycles, and further,
In industrial machinery, etc., to prevent noise and vibration,
A wide variety of anti-vibration rubbers are used. Particularly in the automobile field, with the recent high performance of engines, it has excellent heat resistance, and has excellent fatigue resistance not only in a normal temperature atmosphere but also in a high temperature atmosphere. There is an increasing demand for anti-vibration rubber that can provide a comfortable ride.

The characteristics that such a vibration-proof rubber should have are (1) excellent heat resistance.

(2) Low dynamic magnification (dynamic elastic modulus / static elastic modulus) in order to prevent noise and vibration during high-speed traveling.

(3) Excellent fatigue resistance and durability against repeated external force for a long period under normal temperature or high temperature atmosphere.

And so on.

In addition, static rubber characteristics such as compression set and tear strength are not inferior to normal rubber.
Of course it's important.

As the conventional anti-vibration rubber, high unsaturated rubber such as natural rubber and styrene-butadiene rubber (SBR) is mainly used. This is because highly unsaturated rubbers such as natural rubber and SBR have the advantage that they are superior in fatigue resistance and dynamic characteristics compared to low unsaturated rubbers, while these highly unsaturated rubbers are It is known that, compared with low unsaturated rubber, for example, butyl rubber or ethylene / α-olefin / non-conjugated diene copolymer rubber, it is inferior in heat resistance,
Therefore, the use of the highly unsaturated rubber tends to be limited to the use at a relatively low temperature.

Conversely, low-unsaturated rubbers such as butyl rubber and ethylene / α-olefin / non-conjugated diene copolymer rubbers show excellent heat resistance, but have the drawback of being inferior in fatigue resistance and dynamic characteristics against long-term repeated external force. Therefore, it cannot be used under severe external force and deformation conditions.

<Problems to be Solved by the Invention> Under the circumstances, the present inventors have developed a rubber composition having excellent heat resistance, fatigue resistance to cyclic deformation at room temperature and high temperature, and excellent dynamic characteristics. The present invention has been achieved as a result of intensive studies aimed at Here, the dynamic characteristic is a characteristic represented by a degree of change in elastic modulus (dynamic elastic modulus) at the time of vibration input in a high frequency range, that is, a dynamic magnification (dynamic elastic modulus / static elastic modulus). For the purpose of vibration isolation, a low dynamic magnification is required.

<Means for Solving the Problems> That is, the present invention relates to a method for producing a rubber composition, which comprises the following first step and second step.

First step: 100 parts by weight of a rubber component consisting of ethylene / α-olefin / non-conjugated diene copolymer rubber and / or butyl rubber and 0.1 to 5 parts by weight of at least one dinitrodiamine represented by the following general formula (a). A mixture containing 1
A step of obtaining a heat treatment mixture by heat treatment at a temperature of 20 ° C. or higher.

Second step: a step of adding a filler to the heat treatment mixture and kneading the mixture to obtain a rubber composition.

General formula (a) (In the formula, X is a divalent chain aliphatic group, a cycloaliphatic group or an aromatic group, and the group may contain halogen or oxygen. R ¹ is a hydrogen atom or a chain aliphatic group. A group, a cycloaliphatic group or an aromatic group, but when both X and R ¹ are chain aliphatic groups, the nitrogen atoms may be further linked to each other via R ^{1. 2} and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 12 carbon atoms,
R ² and R ³ may combine to form a ring. ) The details will be described below.

The method of the present invention includes, as essential steps, two steps, the first step and the second step.

The first step is a rubber component 100 composed of ethylene / α-olefin / non-conjugated diene copolymer rubber and / or butyl rubber.
In this step, a mixture containing 1 part by weight and 0.1 to 5 parts by weight of at least one dinitrodiamine represented by the general formula (a) is heat-treated at a temperature of 120 ° C. or higher to obtain a heat-treated mixture.

As the rubber component used in the first step, ethylene / α
-Olefin / non-conjugated diene copolymer rubber and butyl rubber are used alone or together.

Examples of the α-olefin which is one of the constituent components of the ethylene / α-olefin / non-conjugated diene copolymer rubber include propylene, 1-butene and 1-hexene. Also,
Examples of the non-conjugated diene include 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, dicyclopentadiene, 1,4 hexadiene and the like.

The butyl rubber used in the present invention refers to an isobutylene / isobutylene copolymer rubber and a halogenated butyl rubber obtained by denaturing it with bromine or chlorine.

A mixture of 70% by weight or more of the ethylene / α-olefin / non-conjugated diene copolymer rubber and / or butyl rubber and another rubber, for example, natural rubber may be used as the rubber component in the first step.

Specific examples of the dinitrodiamines represented by the general formula (a) used in the present invention include the following compounds. In the following examples, -Z is Indicates.

_{(1) Z-NHCH 2 2} NH-Z (2) Z-NHCH 2 3 NH-Z (3) Z-NHCH 2 4 NH-Z (4) Z-NHCH 2 6 NH-Z (5) Z-NHCH _{2 10} NH-Z (6) Z-NHCH _{2 12} NH-Z (8) NO ₂ CH _{2 2} NHCH _{2 2} NHCH _{2 2} NO ₂ (9) NO ₂ CH _{2 2} NHCH _{2 6} NHCH _{2 2} NO ₂ The amount of dinitrodiamine used is 0.1 to 5 parts by weight per 100 parts by weight of the rubber component. If it is less than this range, the effect of improving the dynamic characteristics is insufficient, and if it is more than this range, the effect is saturated, which is uneconomical.

In the first step, a radical generator may coexist. By using the radical generator, it is possible to further improve the fatigue resistance and dynamic properties of the intended rubber composition.

Examples of the radical generator used here include 2-2'dithiobis-benzothiazole and organic peroxide. The organic peroxide is not particularly limited, and one or more kinds of organic peroxides such as diallyl peroxide, dialkyl peroxide, peroxy ester, and perketal can be used. Specific examples include benzoyl peroxide, 1-1 di-t-butylperoxy 3,3,5 trimethylcyclohexane, di-t-butylperoxydiisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2, Examples include 5, di (t-butylperoxy) hexane and the like.

The amount of the above-mentioned peroxide is not particularly limited, but it is preferably 0.1 to 3 parts by weight per 100 parts by weight of the rubber component. In addition, a polyfunctional monomer such as ethylene dimethacrylate, trimethylpropane trimethacrylate, and triallyl isocyanurate can be used together with these organic peroxides, if necessary.

In the first step, a filler may be added and used in a ratio of 30 parts by weight or less per 100 parts by weight of the rubber component. As the filler, carbon black, silica, talc, calcium carbonate clay and the like which have been conventionally used in the rubber field are used, but from the viewpoint of fatigue resistance, it is preferable to use carbon black. As the type of carbon black, for example, HAF, FEF, SRF black and the like can be used without being limited by the size of its reinforcing property.

When the filler is used in the first step, the amount used should be 30 parts by weight or less per 100 parts by weight of the rubber component. When the amount of the filler used in the first step exceeds the above range, the rubber composition finally obtained becomes unsatisfactory in terms of its dynamic characteristics.

In the first step, a rubber component, dinitrodiamines,
And, if necessary, it is necessary to heat-treat the mixture containing the radical generator and the filler at a temperature of 120 ° C. or higher. A higher temperature at this time is preferable from the viewpoint of improving fatigue resistance and dynamic characteristics, but if it is too high, the rubber deteriorates due to oxidation, so it is preferably completed at 220 ° C. or less in 1 to 40 minutes.

However, when the radical generator is used in the first step without using the filler, the heat treatment temperature of 100 ° C. or higher is sufficient.

The heat treatment in the first step specifically means mixing the mixture at a temperature of 120 ° C. or higher, or mixing the mixture near room temperature and then using an oven or the like to a temperature of 120 ° C. or higher. It is performed by heating. To mix,
For example, an open roll, a closed kneader, an extruder or the like is used.

As a method for adding dinitrodiamines, a solution obtained by dissolving dinitrodiamines in an organic solvent such as hexane may be added to and permeated into the rubber component, and then the organic solvent may be removed by evaporation.

The second step of the present invention is a step of obtaining a rubber composition by blending a filler with the heat treatment mixture obtained in the first step and kneading the mixture.

Examples of the filler used in the second step are the same as those exemplified as the filler that can be used in the first step, and carbon black is most suitable. Then, the filler used in the second step may be the same as or different from the filler used in the first step. The amount of the filler used in the second step is the sum of the amount of the filler used in the first step and the amount of the filler used in the second step of the rubber component weight ratio usually used in the rubber industry. It is regulated to be in the range. That is, the total amount is about 30 to 200 parts by weight per 100 parts by weight of the rubber component.

The kneading carried out in the second step is carried out under the equipment and conditions generally used in the rubber industry and is not particularly limited.

The rubber composition obtained in the second step can be vulcanized by a known method by incorporating a known vulcanizing agent or vulcanization accelerator usually used in the rubber industry.

In the first step and / or the second step, a compounding agent other than the filler of the present invention, such as process oil, zinc white, stearic acid, and processing aid, may be added and used.

<Examples> Hereinafter, the present invention will be specifically described with reference to Examples.
The present invention is not limited to these.

Examples 1 to 6 and Comparative Examples 1 and 2 Under the conditions of the first step shown in Table-1, mixing and heat treatment were performed using a Banbury mixer having an internal capacity of 1.5 l. Next, as a second step, the obtained heat-treated mixture was mixed with FEF Black 100.
Parts by weight, 35 parts by weight of paraffin-based process oil (Diana PW-90 registered trademark manufactured by Idemitsu Kosan Co., Ltd.), 5 parts by weight of zinc white, and 1 part by weight of stearic acid, and using a Banbury mixer at 160 to 170 ° C. Kneaded for 3 minutes. The parts by weight are based on 100 parts by weight of the rubber component used initially (however, the weight of the extender oil is excluded) (hereinafter the same). After cooling the rubber composition thus obtained to room temperature, tetramethylthiuram disulphide 2.0 parts by weight and dibenzothiazyl disulphide 2.5 parts by weight as a vulcanization accelerator,
In addition, 1.2 parts by weight of sulfur was added, and the mixture was kneaded at 40 to 70 ° C. using an open roll to obtain a compound. The viscosity of this compound was measured by the method of JIS K6300.
Further, the compound was heated at 170 ° C. for 10 minutes using a hot press.
It was treated for a minute and molded into a vulcanized sheet having a thickness of 2 mm. Various evaluations were performed using this vulcanized sheet. The tensile test and tear test were performed according to JIS K6301. Other evaluation methods are as follows.

A tanδ viscoelasticity spectrometer was used to measure at a temperature of 30 ° C. and a vibration frequency of 25 Hz.

Dynamic Magnification The static modulus of elasticity (Ks) calculated based on the measured values in accordance with JIS K6383 and 30 using a viscoelasticity spectrometer.
Ratio of dynamic modulus (Kd ₁₀₀ ) (Kd ₁₀₀ /
Ks).

Elongation Fatigue Property Using a bending fatigue tester manufactured by Monsanto, strain rate 0 to 15
Under the condition of 0%, the number of stretches before breaking was measured.

The results are shown in Table-1.

Example 7 The mixture obtained under the same conditions as in the first step of Comparative Example 1 was made into a sheet having a thickness of about 5 mm by using an open roll (40 to 60 ° C.) and heat-treated in a 160 ° C. oven for 10 minutes. The first step was completed by. Operations after the second step and various evaluations were performed in the same manner as in Examples 1 to 6. The results are shown in Table-1.

Examples 8 to 11 Under the conditions of the first step shown in Table 2, mixing and heat treatment were performed using a Banbury mixer having an internal capacity of 1.5 l. Next table
Under the conditions of the second step shown in 2, kneading was performed for 3 hours at 160 to 170 ° C. using a Banbury mixer. Next, 2.0 parts by weight of tetramethylthiuram disulphide and 2.5 parts by weight of dibenzothiazyl disulphide (however, 2.0 parts by weight in Example 9) as a vulcanization accelerator, and 1.2 parts by weight of sulfur were added, and an open roll was used. Kneading at 40-70 ℃,
I got a compound. The subsequent operations and evaluations were performed in the same manner as in Example 1. The results are shown in Table-2.

Comparative Examples 3 and 4 Examples 8 to 11 except that the second step was not compounded and kneaded.
Conducted as in 11. The results are shown in Table-2.

<Effects of the Invention> As described above, according to the present invention, it is possible to provide a method for producing a rubber composition having excellent heat resistance, fatigue resistance against repeated deformation in normal temperature and high temperature atmosphere, and excellent dynamic characteristics. did it.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // (C08K 13/02 3:00 5:14 5:32) (72) Inventor Hideo Nagasaki Osaka City, Osaka Prefecture No. 3-98 Kasugadechu, Konohana-ku, Sumitomo Chemical Co., Ltd. (56) Reference JP-A-3-170539 (JP, A) JP-A-3-54235 (JP, A) JP-A 1-117848 (JP, A) JP 64-81838 (JP, A) JP 63-23942 (JP, A)

Claims (2)

[Claims] 1. A method for producing a rubber composition comprising the following first step and second step. First step: 100 parts by weight of a rubber component consisting of ethylene / α-olefin / non-conjugated diene copolymer rubber and / or butyl rubber and 0.1 to 5 parts by weight of at least one dinitrodiamine represented by the following general formula (a). 120 containing mixture
A step of obtaining a heat treatment mixture by heat treatment at a temperature of ℃ or higher. Second step: a step of adding a filler to the heat treatment mixture and kneading the mixture to obtain a rubber composition. General formula (a) (In the formula, X is a divalent chain aliphatic group, a cycloaliphatic group or an aromatic group, and the group may contain halogen or oxygen. R ¹ is a hydrogen atom or a chain aliphatic group. A group, a cycloaliphatic group or an aromatic group, but when both X and R ¹ are chain aliphatic groups, the nitrogen atoms may be further linked to each other via R ^{1. 2} and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and R ² and R ³ may combine to form a ring.) 2. The first step comprises ethylene / α-olefin /
100 parts by weight of a rubber component consisting of a non-conjugated diene copolymer rubber and / or butyl rubber, 0.1 to 5 parts by weight of at least one dinitrodiamine represented by the general formula (a), and a mixture containing a radical generator, The method according to claim (1), which is a step of obtaining a heat-treated mixture by performing heat treatment at a temperature of not less than ° C.