JP2001181458A - Epdm-based rubber composition and epdm-based vulcanized rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an EPDM-based vulcanized rubber improved in heat resistance and an EPDM-based rubber composition capable of presenting the vulcanized rubber. SOLUTION: In an EPDM-based rubber composition comprising (1) an EPDM- based rubber, (2) carbon black, (3) antioxidant and (4) a cross-linking agent, a p-phenylenediamine-based compound having a terminal double bond is used as the antioxidant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an EPDM rubber composition and an EPDM vulcanized rubber. EP of the present invention
The DM rubber composition is vulcanized and used for various applications. In particular, the vulcanized EPDM-based vulcanized rubber of the present invention is useful as an elastic member of a vibration-proof rubber used for various vehicles, machines, bridges, railway tracks and other structures. Especially, because of its excellent heat resistance, for example, engine mount, body mount, cab mount, member mount, strut bar cushion, center bearing support, torsion damper, steering rubber coupling, tension rod bush, lower ring bush, arm bush , Bump strapper, FF
It is suitable as an elastic member of a vibration-proof rubber for various automobiles such as an engine roll stopper and a muffler hanger.

[0002]

2. Description of the Related Art Automobile engines and the like are made of anti-vibration rubber.
Engine vibration and the accompanying noise are reduced.
Such anti-vibration rubber is required not only to have anti-vibration performance but also to have heat resistance to heat generated by an engine or the like.

[0003] Conventionally, as such a vibration-proof rubber, a rubber obtained by vulcanizing a synthetic rubber such as natural rubber (NR), butadiene rubber (BR), and styrene-butadiene rubber (SBR) has been used. However, the various rubber components are
Basically, the heat resistance is poor due to the double bond in the main chain, and when used for a long time in a high temperature environment such as an automobile engine, thermal degradation and dynamic fatigue are remarkable.

In order to solve such a problem, it has been proposed to use a heat-resistant EPDM rubber having no double bond in the main chain as a rubber component of the vibration damping rubber. However, in recent years, the heat resistance required by an automobile engine room or the like has become higher. For example, with the tightening of exhaust gas regulations, it is necessary to improve the efficiency of the catalyst in the muffler, so the muffler becomes hot to make the catalyst function at a high temperature, and the muffler hanger also requires high heat resistance. Even when an EPDM rubber is used as a component, further improvement in heat resistance is desired.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an EPDM vulcanized rubber having improved heat resistance and an EPDM rubber composition which can be the vulcanized rubber.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies on an antioxidant to be added to an EPDM rubber composition.
The present inventors have found that the above object can be achieved by using a p-phenylenediamine compound having a double bond at a terminal and by using nickel dialkyldithiocarbamate, and have completed the present invention.

That is, the present invention provides an EPDM rubber composition comprising (1) EPDM rubber, (2) carbon black, (3) an antioxidant, and (4) a crosslinking agent. The present invention relates to an EPDM rubber composition characterized in that a p-phenylenediamine compound having a double bond at a terminal is used as an inhibitor.

A p-phenylenediamine compound having a double bond at the terminal acts not only as an antiaging agent, but also reacts with the (1) EPDM rubber because the double bond at the terminal is reactive. As a result, it is inferred that the heat resistance of the EPDM vulcanized rubber was improved.

Further, the present invention provides (1) an EPDM rubber,
An EPDM rubber composition containing (2) carbon black, (3) an antioxidant, and (4) a crosslinking agent, wherein (3) nickel dialkyldithiocarbamate is used as the antioxidant. EPDM
A rubber composition.

[0010] Nickel dialkyldithiocarbamate has a function of oxidizing peroxy radicals generated when EPDM rubber deteriorates to sulfoxide, and acts as an anti-aging agent, so that the heat resistance of EPDM vulcanized rubber is improved. It is presumed to have been done. Nickel dialkyldithiocarbamate has p-terminal having a double bond at the terminal.
The effect of improving heat resistance is greater than that of the phenylenediamine compound.

Further, the present invention provides an EPDM rubber composition comprising (1) an EPDM rubber, (2) carbon black, (3) an antioxidant, and (4) a crosslinking agent. EP, characterized by using a p-phenylenediamine compound having a double bond at a terminal and a nickel dialkyldithiocarbamate as an aging inhibitor.
A DM rubber composition.

The p-phenylenediamine compound having a double bond at the terminal and nickel dialkyldithiocarbamate can be used in combination, and exhibit an excellent heat resistance improving effect.

The compounding ratio of the p-phenylenediamine compound having a double bond at the terminal is preferably about 0.5 to 4% by weight based on (1) the EPDM rubber. The lower limit of the mixing ratio is a preferable range of the mixing ratio at which the effect of heat resistance is further improved, and from the viewpoint of the effect of improving heat resistance, the mixing ratio is more preferably 1.5% by weight or more. . On the other hand, the upper limit of the mixing ratio is p-
When the amount of the phenylenediamine-based compound increases, the dynamic magnification and the sag property (thermal deterioration) tend to be deteriorated. Therefore, the balance with these properties is taken into consideration. % Is more preferable. In addition, from the viewpoint of heat resistance, there is no particular problem even if the p-phenylenediamine-based compound is used in an amount exceeding the above-mentioned mixing ratio.

The compounding ratio of the nickel salt of dialkyldithiocarbamic acid is (1) 0.5 to EPDM rubber.
It is preferably about 4% by weight. The lower limit of the compounding ratio is a preferable range of the compounding ratio at which the effect of heat resistance is further improved, and from the viewpoint of the effect of improving heat resistance, the compounding ratio is more preferably 1% by weight or more. On the other hand, even when the blending ratio is increased, the tendency that the dynamic magnification and the sag property (thermal deterioration) deteriorate as in the case of the p-phenylenediamine compound is not particularly recognized. It is preferable that the proportion be 4% by weight or less.

(2) a p-phenylenediamine compound having a double bond at the terminal,
When an imidazole compound is used in addition to the nickel dialkyldithiocarbamate, the effect of improving heat resistance is remarkably improved. Since the effect of improving the heat resistance is hardly recognized even when the imidazole compound is used alone, the effect of improving the heat resistance is considered with respect to the p-phenylenediamine compound having a double bond at the terminal, nickel dialkyldithiocarbamate and imidazole. A synergistic effect due to the compound is observed.

The mixing ratio of the imidazole compound is as follows:
(1) The content is preferably about 0.5 to 4% by weight based on the EPDM rubber. The lower limit of the compounding ratio is a preferable range of the compounding ratio at which the effect of heat resistance is further improved, and from the viewpoint of the effect of improving heat resistance, the compounding ratio is more preferably 1.5% by weight or more. . On the other hand, the upper limit of the compounding ratio is such that when the amount of the imidazole-based compound increases, the dynamic magnification and the sag property (thermal deterioration) tend to be deteriorated. For example, it is more preferable that the mixing ratio be 3% by weight or less. In addition, from the viewpoint of heat resistance, there is no particular problem even if the imidazole-based compound is used in a proportion exceeding the above-mentioned mixing ratio.

The carbon black (2) used as a filler includes a nitrogen adsorption specific surface area of 15 to 70 m.
It is preferable to use those having a ratio of about ² / g because of excellent dynamic magnification, strength (breaking strength), and sag. Since the strength tends to decrease as the nitrogen adsorption specific surface area decreases, the nitrogen adsorption specific surface area is more preferably set to 30 m ² / g or more. Also, since the dynamic magnification tends to decrease as the nitrogen adsorption specific surface area increases, the nitrogen adsorption specific surface area is 60 m
More preferably, it is ² / g or more. In addition, from the viewpoint of heat resistance, there is no particular problem even if it is out of the above range, but it is preferable to be within the above range from the viewpoint of heat resistance.

Such an EPDM rubber composition is vulcanized by various means into an EPDM vulcanized rubber, which is used for various purposes. Such an EPDM vulcanized rubber is molded into various shapes and provided for various uses. However, since it has excellent heat resistance, it is particularly useful as an elastic member of a vibration-proof rubber.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) EPDM rubber is an amorphous random elastic copolymer obtained from ethylene and α-olefin as main components and a small amount of a non-conjugated diene monomer. Examples of the α-olefin include propylene, butylene (1-butene), isobutylene (2-methylpropene), 1-pentene and the like, and propylene is particularly preferred. As the non-conjugated diene monomer, one having about 5 to 20 carbon atoms is usually used.
Chain dienes such as pentadiene, 1,4-hexadiene, 1,5-hexadiene, 2,5-dimethyl-1,5-hexadiene and 1,4-octadiene, 1,4-cyclohexadiene, cyclooctadiene, dicyclo Cyclic diene such as pentadiene, alkenyl norbornene such as 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, 2-methallyl-5-norbornene and 2-isopropenyl-5-norbornene; among these, , Dichloropentadiene and 5-ethylidene-2-norbornene are preferably used.

(1) The proportion of the monomer constituting the EPDM rubber usually contains about 45 to 75% by weight of ethylene and about 4 to 15% by weight of a non-conjugated diene monomer. Also, (1)
The average molecular weight of EPDM rubber is usually 500,000 to 150.
Thousands are used.

(2) Carbon black is (1) EPD
Used as a reinforcing agent for M-based rubber and improves durability. (2) There are no restrictions on the production method and properties of the carbon black, and various types can be used.
Those having ^{5 to} 70 m ² / g are preferred because they have excellent dynamic magnification, strength (breaking strength) and sag. In addition, the nitrogen adsorption specific surface area is measured by ASTM D3037.

(2) The blending ratio of carbon black is not particularly limited, and the blending ratio is appropriately determined according to the application in order to adjust the strength of the EPDM vulcanized rubber.
Usually, in order to function sufficiently as a reinforcing agent, (1)
About 0.1% by weight or more based on EPDM rubber;
More preferably, the content is 1% by weight or more. The upper limit of the mixing ratio is about 150% by weight or less,
% By weight or less.

(3) A p-phenylenediamine compound having a double bond at a terminal, which is used as an anti-aging agent, has a p-phenylenediamine skeleton, and has an acryloyl group, a methacryloyl group at a molecular terminal of the compound. Group,
It has at least one double bond such as a vinyl group, a vinylidene group and an α-olefin group. As the double bond, an acryloyl group or a methacryloyl group having high reactivity is preferable. As a typical example of such a p-phenylenediamine-based compound, general formula (1): Ph ¹ -NH-Ph ^2-
N (wherein Ph ¹ represents a phenyl group, Ph ² represents a phenylene group, and R represents a substituent having a double bond at the terminal) N-phenyl-N ′-(R-substituted) -p-phenylene Diamines. Specific examples of R include a 3-methacryloyloxy-2-hydroxypropyl group and a 4-pentenyl group.

The p-phenylenediamine compound is used in an amount of usually not more than about 5% by weight based on the (1) EPDM rubber, so that the heat resistance of the vulcanized rubber is improved. The use ratio is preferably about 0.5 to 4% by weight.

(3) used as an anti-aging agent,
Examples of the nickel dialkyldithiocarbamate include the following general formula (2):

Embedded image (Wherein, R ¹ represents an alkyl group having about 1 to 8 carbon atoms). As R ¹ ,
Examples thereof include an ethyl group, a butyl group, a hexyl group and the like, and R ¹ in the general formula (2) may be the same or different.

The proportion of the nickel dialkyldithiocarbamate used is generally in the range of about 5% by weight or less based on (1) the EPDM rubber, in a range in which the heat resistance of the vulcanized rubber is improved. The use ratio is preferably 0.
It is about 5 to 4% by weight.

The p-phenylenediamine-based compound having a double bond at the terminal and a nickel dialkyldithiocarbamate can be used in combination.

As the imidazole compound, various compounds having an imidazole skeleton can be used. Specifically, metal salts such as 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, and zinc salts thereof can be exemplified. The imidazole compound is
In addition to the p-phenylenediamine-based compound, the present invention further improves the heat resistance of the vulcanized rubber, and (1) EP
It is usually used in a range of about 5% by weight or less based on the DM rubber. The use ratio is preferably about 0.5 to 4% by weight.

(4) As a cross-linking agent, sulfur used for vulcanization of rubber, organic peroxide, or the like is used. Specific examples of the organic peroxide include benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide,
t-butylcumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,
5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (t- Butylperoxy) hexyne-3 or 1,3
-Bis (t-butylperoxypropyl) benzene, di-t-butylperoxy-diisopropylbenzene, t
-Butylperoxybenzene, 2,4-dichlorobenzoyl peroxide, 1,1-di-t-butylperoxy-3,3,5-trimethylsiloxane, n-butyl-
4.4-di-t-butylperoxyvalerate and the like.

(4) The proportion of the crosslinking agent used is (1) EPD
It can be appropriately determined for the M-based rubber according to the type of the crosslinking agent. For example, when the cross-linking agent is sulfur, usually 0.1
About 5% by weight, and in the case of an organic peroxide, usually 0.1%.
It is about 1 to 20% by weight. The EPDM rubber composition of the present invention contains (1) an EPDM rubber, (2) carbon black, (3) an antioxidant, and (4) a crosslinking agent. Mixing softeners, co-crosslinking agents, vulcanization accelerators, accelerators, processing aids, fillers, etc., used as additives for rubber, in the same proportions as those conventionally used Can be. Further, (2) a reinforcing material other than carbon black and an anti-aging agent other than those exemplified above may be blended as long as the object of the present invention is not impaired.

As the softener, process oil,
Lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petroleum softeners such as petrolatum, castor oil, linseed oil,
Fatty oil-based softeners such as rapeseed oil and coconut oil, tall oil, beeswax, carnauba wax, waxes such as lanolin, and fatty acids such as linoleic acid, palmitic acid, stearic acid, and lauric acid.

The EPDM rubber composition of the present invention comprises (1)
EPDM rubber, (2) carbon black, (3)
An anti-aging agent and (4) a crosslinking agent, and further, an additive can be prepared by mixing according to a conventional method.
PDM-based rubber composition is vulcanized and molded by heating to EP
It becomes a DM vulcanized rubber.

That is, according to a conventional method, (4) after preliminarily mixing the components except for the crosslinking agent, kneading at 80 to 140 ° C. for several minutes, and adding (4) the crosslinking agent to the kneaded material. And then kneading to prepare an EPDM rubber composition. For the kneading, a mixing device such as a mixing roll, a Banbury mixer, a kneader or the like is used, and the mixture is formed into various shapes by various methods such as press molding, transfer molding and injection molding.

[0034]

EXAMPLES The present invention will be described below with reference to comparative examples and examples, but the present invention is not limited to these examples. The method of the evaluation test is as follows.

(Heat resistance) JIS K6251, JIS
Performed according to K6257. The prepared sheet (sample) was aged at 150 ° C. in an oven, and expressed as a time until the breaking strength of the aged sheet reached 60% of the breaking strength of the unaged sheet. The time was 100 for Comparative Example 1.
And expressed as a relative value.

(Dynamic magnification) A dynamic magnification (dynamic spring constant / static spring constant) was measured according to JIS K 6385.

(Sagging property) According to JIS K 6262 (heat treatment at 150 ° C. for 72 hours), compression set (%)
Was measured.

(Break strength) Measured (MPa) according to JIS K6251.

Comparative Example 1 Based on the following composition, raw materials were melt-kneaded to prepare an unvulcanized EPDM rubber composition, which was vulcanized and molded at 160 ° C. for a predetermined time to obtain an EPDM vulcanized rubber. Was prepared.

[0040]

[Blending composition] (1) 100 parts by weight of EPDM rubber (manufactured by JSR Corporation, trade name: 103AF) (2) Carbon black (manufactured by Tokai Carbon Co., Ltd., trade name: Seast SO, nitrogen adsorption specific surface area: 42 m ² / g) 70 Parts by weight (3) Antioxidant (Ouchi Shinko Chemical, trade name Nocrack 224: 2,2,4-trimethyl-1,2-dihydroquinoline polymer) 2 parts by weight (4) Crosslinking agent: sulfur 5 parts by weight (Other additives) Paraffin oil (manufactured by Idemitsu Kosan Co., Ltd., trade name: PW380) 65 parts by weight Zinc flower 3 parts by weight Stearic acid 1 part by weight Vulcanization accelerator (manufactured by Ouchi Shinko Chemical, trade name Noxera-TT- P) 0.75 parts by weight (trade name: Noxera-TTFE manufactured by Ouchi Shinko Chemical Co., Ltd.) 0.75 parts by weight Comparative Examples 2 to 4, Examples 1 to 17 In Comparative Example 1, (3) the type and age of the antioxidant An unvulcanized EPDM rubber composition was prepared in the same composition as in Comparative Example 1 except that the amount used was changed as shown in Table 1, Table 2 or Table 3, and vulcanized at 160 ° C. for a predetermined time. -Molding was performed to produce an EPDM vulcanized rubber.

Test Example 1 Using the EPDM vulcanized rubber (sample) obtained above, an evaluation test was conducted for heat resistance, dynamic magnification, and set resistance. The evaluation results are shown in Tables 1, 2 and 3.

[0043]

[Table 1]

[Table 2]

[Table 3] In Tables 1, 2, and 3, the type of the antioxidant is Ph diamine-based A: N-phenyl-N '-(1,3-dimethylbutyl) -p-phenylenediamine (manufactured by Flexis, trade name: Santo Flex 6PPD), Ph diamine-based B: N-phenyl-N '-(3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine IM-based A: 2-mercaptobenzimidazole zinc salt (manufactured by Ouchi Shinko Chemical Co., Ltd. IM-based B: 2-mercaptomethylbenzimidazole (trade name: MMB, manufactured by Ouchi Shinko Chemical Co., Ltd.), carbamic acid-based: nickel dibutyldithiocarbamate, and numerical values indicate the blending parts by weight.

As shown in the results of Tables 1 and 2, in the Examples, Ph-diamine-based B corresponding to p-phenylenediamine-based compound having a double bond at a terminal was used as an anti-aging agent. Excellent in nature. In particular, Example 5
In No. 10, the heat resistance is remarkably improved because the Ph diamine-based and IM-based antioxidants are blended at a specific use ratio. Furthermore, it is recognized that the dynamic magnification is as small as 1.9 or less, and the sag is 70% or less, and that the rubber composition is excellent in performance as an anti-vibration rubber.

As shown in the results of Table 3, nickel dialkyldithiocarbamate is used as an antioxidant, so that it has excellent heat resistance. In particular, when a predetermined amount or more of nickel dialkyldithiocarbamate is used, the effect of improving heat resistance is large. Further, when an IM-based antioxidant is added, the heat resistance is remarkably improved. In addition, the dynamic magnification was as small as 1.9 or less, and the sag was 70% or less, and it was recognized that the rubber composition was excellent in performance as an anti-vibration rubber.

Examples 18 to 21 In Comparative Example 1, (3) the type and amount of the antioxidant were changed as in Example 5 shown in Table 1, and the type and amount of carbon black were as shown in Table 4. Other than changing to
An unvulcanized EPDM rubber composition was prepared with the same composition as in Comparative Example 1, and then vulcanized and molded in accordance with the test method described later to produce an EPDM rubber vulcanized.

Test Example 2 Using the EPDM vulcanized rubber (sample) obtained above, an evaluation test was conducted on the heat resistance, dynamic magnification, set resistance, and breaking strength by the following methods. Table 4 shows the evaluation results.

[0048]

[Table 4] In Table 4, the types of carbon black are: carbon black A (manufactured by Tokai Carbon Co., trade name: Seast SO, nitrogen adsorption specific surface area: 42 m ² / g); carbon black B (manufactured by Tokai Carbon Co., trade name: Seast 3, nitrogen adsorption) Specific surface area 79 m ² / g), carbon black C (manufactured by Showa Cabot Co., trade name N3
51, nitrogen adsorption specific surface area 69 m ² / g) Carbon black D (manufactured by Tokai Carbon Co., Ltd., Seast S, nitrogen adsorption specific surface area 27 m ² / g) carbon black E (manufactured by Asahi Carbon Co., trade name Asahi # 1)
5, specific surface area of nitrogen adsorption: 12 m ² / g), and the numerical values indicate the parts by weight.

As shown in the results of Table 4, the examples have excellent heat resistance regardless of the type of carbon black. Further, in Examples 19 and 20, the dynamic magnification was as small as 1.9 or less, the sag was 70% or less, and the breaking strength was 18 MPa or more because carbon black having a nitrogen adsorption specific surface area in a predetermined range was used. There is also excellent performance as a vibration-proof rubber.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/14 C08K 5/14 5/18 5/18 5/3445 5/3445 5/39 5/39 ( 72) Inventor Riichiro Ohara 1-17-18 Edobori, Nishi-ku, Osaka-shi, Osaka F-term (reference) in Toyo Tire & Rubber Co., Ltd. EK019 EK029 EK039 EK049 EK069 EK079 EN077 EU118 EV158 FD016 FD020 FD067 FD068 FD149 GL00 GN00

Claims (10)

[Claims] 1. An EPDM rubber composition comprising (1) an EPDM rubber, (2) carbon black, (3) an antioxidant, and (4) a crosslinking agent, wherein (3) the antioxidant is An EPDM-based rubber composition using a p-phenylenediamine-based compound having a double bond at a terminal. 2. An EPDM rubber composition comprising (1) an EPDM rubber, (2) carbon black, (3) an antioxidant, and (4) a crosslinking agent. An EPDM rubber composition comprising a nickel dialkyldithiocarbamate. 3. An EPDM rubber composition containing (1) an EPDM rubber, (2) carbon black, (3) an antioxidant, and (4) a crosslinking agent, wherein (3) an antioxidant is An EPDM rubber composition comprising a p-phenylenediamine compound having a double bond at a terminal and a nickel dialkyldithiocarbamate. 4. The EPDM rubber according to claim 1, wherein the compounding ratio of the p-phenylenediamine compound having a double bond at the terminal is 0.5 to 4% by weight based on (1) the EPDM rubber. Composition. 5. The mixing ratio of the nickel salt of dialkyldithiocarbamic acid is 0.5 to 0.5% with respect to (1) the EPDM rubber.
The EPD according to any one of claims 2 to 4, which is 4% by weight.
M-based rubber composition. 6. The EPDM rubber composition according to claim 1, further comprising (3) an imidazole compound as an antioxidant. 7. The compounding ratio of the imidazole compound is as follows:
(1) The EPDM rubber composition according to claim 6, which is 0.5 to 4% by weight based on the EPDM rubber. 8. A carbon black having a specific surface area for nitrogen adsorption of 15 to 70 m ² / g as the carbon black.
An EPDM rubber composition according to any one of claims 1 to 7. 9. The EPD according to claim 1,
EPDM vulcanized rubber obtained by vulcanizing an M-based rubber composition. 10. An anti-vibration rubber using the EPDM vulcanized rubber according to claim 9 as an elastic member.