JP5323607B2 - Heat resistant acrylic rubber composition - Google Patents

Description

  The present invention relates to a heat resistant acrylic rubber composition, and more particularly to a heat resistant acrylic rubber composition capable of producing a rubber product having excellent heat resistance even after being exposed to a high temperature for a long time.

  Acrylic rubber is used for hose parts, seal parts, anti-vibration rubber parts and the like because it exhibits excellent characteristics even in a high heat environment. When used in the intake / exhaust systems of automobile fuel systems, lubricating oil systems, hoses in engine rooms, etc., heat resistance, oil resistance, weather resistance, heat aging resistance, ozone resistance, etc. are required. Furthermore, low compression set is also required. In particular, higher heat resistance is required under the influence of recent exhaust gas countermeasures and higher engine output.

  Various studies have been made on acrylic rubber compositions that satisfy these requirements. For example, an acrylic rubber composition containing a carboxyl group-containing acrylic rubber, a secondary diamine anti-aging agent, and a vulcanizing agent is excellent in normal physical properties and compression set properties, and has a tensile strength even after heat aging. It is disclosed that the rate of change in elongation can be suppressed without sacrificing the thickness (see, for example, Patent Document 1).

  An acrylic rubber used in combination with an easily-movable antioxidant derived from alkylated diphenylamines and an antioxidant composed of a compound having a diphenylamine skeleton and the like and having a cumyl group at both ends of the aromatic ring It is disclosed that the antioxidant for use can sufficiently improve the anti-aging action at high temperatures due to the synergistic effect of the same kind of antioxidants (for example, see Patent Document 2).

  Furthermore, an acrylic rubber composition obtained by adding a styrenated diphenylamine compound to a carboxyl group-containing acrylic rubber does not impair processability, mechanical properties, and compression set properties during vulcanization, and is heat resistant in use. In particular, it is disclosed that the balance between the rate of change in tensile strength and the rate of change in elongation is excellent (see, for example, Patent Document 3).

JP 2009-7491 A Japanese Patent Laid-Open No. 11-21411 International Publication No. 2006/001299

  However, the conventional acrylic rubber composition cannot sufficiently cope with the heat resistance required for acrylic rubber (particularly the heat resistance when exposed to high temperature for a long time), and higher performance is required. ing.

  The present invention has been made in view of such problems of the prior art, and the object of the present invention is to provide heat resistance capable of producing a rubber product having excellent heat resistance even after being exposed to a high temperature for a long time. The object is to provide an acrylic rubber composition.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors can achieve the above-mentioned problems by including acrylic rubber and a plurality of anti-aging agents including a diphenylamine derivative and a phenothiazine derivative. As a result, the present invention has been completed.

  That is, according to the present invention, the following heat-resistant acrylic rubber composition is provided.

Containing acrylic rubber, a diphenylamine derivative represented by the following general formula (1), and a plurality of anti-aging agents including a phenothiazine derivative represented by the following general formula (2), the total content of the anti-aging agents The heat resistant acrylic rubber composition whose quantity is 1.0-6.0 mass parts with respect to 100 mass parts of said acrylic rubber.

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 18 carbon atoms which may be substituted with an aromatic ring. Show.

In the general formula (2), R ³ and R ⁴ are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 18 carbon atoms which may be substituted with an aromatic ring, or An alkoxyl group having 1 to 8 carbon atoms is shown. However, at least one of R ³ and R ^{4 represents} a linear or branched alkyl group having 1 to 18 carbon atoms which may be substituted with an aromatic ring, or an alkoxyl group having 1 to 8 carbon atoms. .

  The heat-resistant acrylic rubber composition of the present invention has an effect that it is possible to produce a rubber product having excellent heat resistance even after being exposed to a high temperature for a long time.

  Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments, and based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that modifications, improvements, and the like appropriately added to the embodiments described above fall within the scope of the present invention.

The heat-resistant acrylic rubber composition of the present invention contains acrylic rubber and a plurality of antioxidants including a diphenylamine derivative and a phenothiazine derivative . The total content of the anti-aging agent is 1.0 to 6.0 parts by mass with respect to 100 parts by mass of the acrylic rubber. The heat-resistant acrylic rubber composition of the present invention can be suitably used as a material for members of automobiles and the like because a rubber product having excellent heat resistance can be produced even after being exposed to a high temperature for a long time.

1 Acrylic rubber The acrylic rubber is not particularly limited, and generally available acrylic rubber can be used. Specific examples of such acrylic rubber include Nipol AR series manufactured by Zeon Corporation, Denka ER series manufactured by Denki Kagaku Kogyo Co., Ltd., Knox Tight series manufactured by NOK Corporation, Toaaklon series manufactured by Toupe Corporation, and DuPont Corporation The Vmac series can be listed.

2 A plurality of anti-aging agents By containing a plurality of anti-aging agents, the heat-resistant acrylic rubber composition of the present invention can produce a rubber product having excellent heat resistance even after being exposed to a high temperature for a long time. . The total content of the anti-aging agent is 1.0 to 6.0 parts by mass, preferably 2.0 to 5.0 parts by mass, with respect to 100 parts by mass of the acrylic rubber. More preferably, it is 4.0 parts by mass. When the total content of the anti-aging agent is less than 1.0 part by mass, the effect of containing the anti-aging agent is not sufficient, and the heat resistance may not be sufficiently improved. On the other hand, if it exceeds 6.0 parts by mass, there is a case where the effect is not affected even if the amount is increased further, and the economy is inferior.

A plurality of anti-aging agent is one which comprises a di-phenyl derivative, a phenothiazine derivative. Further, as the other anti-aging agents, for example, monophenols derivatives, polyphenols derivatives, hydroquinone derivatives, quinone derivatives, amine-ketone derivatives, diaryl amine derivatives, may include other antioxidants paraphenylenediamine induction and the like .

(1 -1) diphenylamine derivative diphenylamine derivatives, Ru compound der represented by the general formula (1).

In General Formula (1), R ¹ and R ² each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 18 carbon atoms which may be substituted with an aromatic ring. .

  Although it does not specifically limit as a compound represented by General formula (1), Specifically, diphenylamine, styrenated diphenylamine, 4,4'- dicumyl diphenylamine, 4,4'-bis ((alpha)-). Methylbenzyl) diphenylamine, 4,4′-dimethyldiphenylamine, 4,4′-diethyldiphenylamine, 4,4′-dipropyldiphenylamine, 4,4′-dibutyldiphenylamine, 4,4′-dipentyldiphenylamine, 4,4 ′ -Dihexyldiphenylamine, 4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, 4,4'-dinonyldiphenylamine, 4,4'-didecyldiphenylamine, 4,4'-diundecyldiphenylamine, 4, Mention 4'-didodecyldiphenylamine It is possible. Among these, 4,4′-dicumyldiphenylamine, styrenated diphenylamine, 4,4′-dibutyldiphenylamine, and 4,4′-dioctyldiphenylamine are preferable, 4,4′-dicumyldiphenylamine, styrenated diphenylamine, 4, More preferred is 4'-dioctyldiphenylamine.

  The content of the diphenylamine derivative is preferably 0.5 to 3.0 parts by mass, more preferably 0.75 to 2.5 parts by mass, with respect to 100 parts by mass of the acrylic rubber. It is especially preferable that it is -2.0 mass parts. When the content of the diphenylamine derivative is less than 0.5 parts by mass, the synergistic effect due to the inclusion of a plurality of antioxidants may not be obtained. On the other hand, if it exceeds 3.0 parts by mass, the effect is not affected even if the amount is increased further, and the economy may be inferior.

(2) Other anti-aging agents Other anti-aging agents are not particularly limited. For example, monophenol derivatives, polyphenol derivatives, hydroquinone derivatives, quinone derivatives, amine / ketone derivatives, diarylamine derivatives, paraphenylene there is a diamine induction and the like.

(Monophenol derivative)
The monophenol derivative is not particularly limited. Specifically, 2,6-di-tert-butyl-p-cresol, p-methoxyphenol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, stearyl-β- (3 , 5-di-tert-butyl-4-hydroxyphenyl) propionate, styrenated phenol and the like.

(Polyphenol derivative)
The polyphenol derivative is not particularly limited. Specifically, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,2′-dihydroxy-3, 3′-di (α-methylcyclohexyl) -5,5′-dimethyldiphenylmethane, 4,4′-thiobis (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6- tert-butylphenol), tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane, 1,3,5-tris (3 ′, 5′-di) -Tert-butyl-4'-hydroxybenzyl) -S-triazine-2,4,6- (1H, 3H, 5H) trione, tocopherol and the like.

(Hydroquinone derivative)
The hydroquinone derivative is not particularly limited. Specifically, hydroquinone, 2,5-di-tert-butyl-hydroquinone, methylhydroquinone, t-butylhydroquinone, methylenebis (2-methylhydroquinone), ethylidenebis (2-t-butylhydroquinone), ethylidenebis (2 -Methyl hydroquinone), isobutylidene bis (2-methyl hydroquinone), methylene bis (2-t-butyl hydroquinone) and the like.

(Quinone derivative)
The quinone derivative is not particularly limited. Specific examples include p-benzoquinone, methyl p-benzoquinone, t-butyl-p-benzoquinone, 2,5-diphenyl-p-benzoquinone, and the like.

(Amine and ketone derivatives)
The amine / ketone derivative is not particularly limited. Specifically, a reaction product of aniline and acetone (trade names “Nonflex RD”, “Nonflex QS”, manufactured by Seiko Chemical Co., Ltd.), a reaction product of p-phenetidine and acetone (trade names “Nonflex AW”, “ Non-flex AW-P ", manufactured by Seiko Chemical Co., Ltd.), a reaction product of diphenylamine and acetone (trade names" Nonflex BA "," Nonflex BA-P ", manufactured by Seiko Chemical Co., Ltd.).

(Diarylamine derivatives)
The diarylamine derivative is not particularly limited. Specifically, diphenylamine, styrenated diphenylamine, 4,4′-dicumyldiphenylamine, 4,4′-bis (α-methylbenzyl) diphenylamine, 4-t-butoxydiphenylamine, 4,4′-di-t- Butoxydiphenylamine, 4,4'-dimethyldiphenylamine, 4,4'-diethyldiphenylamine, 4,4'-dipropyldiphenylamine, 4,4'-dibutyldiphenylamine, 4,4'-dipentyldiphenylamine, 4,4'-dihexyl Diphenylamine, 4,4′-diheptyldiphenylamine, 4,4′-dioctyldiphenylamine, 4,4′-dinonyldiphenylamine, 4,4′-didecyldiphenylamine, 4,4′-diundecyldiphenylamine, 4,4 ′ -Didodecyl diphenylamine etc. It can be.

(Paraphenylenediamine derivative)
The paraphenylenediamine derivative is not particularly limited. Specifically, p-phenylenediamine, p-phenylenediamine sulfate, nitro-p-phenylenediamine, 4-aminodiphenylamine, N, N′-diphenyl-p-phenylenediamine, N-isopropyl-N′-phenyl- p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N-phenyl-N '-(3-methacryloyloxy-2- Hydroxypropyl) -p-phenylenediamine, N, N′-bis (1-methylheptyl) -p-phenylenediamine, N, N′-bis (1,4-dimethylpentyl) -p-phenylenediamine, N, N '-Bis (1-ethyl-3-methylpentyl) -p-phenylenediamine, N- (1,3-dimethylbuty ) -N'-phenyl-p-phenylenediamine, phenylhexyl-p-phenylenediamine, phenyloctyl-p-phenylenediamine, N- (1-methylheptyl) -N'-phenyl-p-phenylenediamine, N- ( 4-anilinophenyl) methacrylamide and the like.

(1-2) phenothiazine-induced body phenothiazine-induced body is a phenothiazine derivative represented by the general formula (2).

In general formula (2), R ³ and R ⁴ are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 18 carbon atoms which may be substituted with an aromatic ring, or carbon. The alkoxyl group of number 1-8 is shown. However, at least one of R ³ and R ^{4 represents} a linear or branched alkyl group having 1 to 18 carbon atoms which may be substituted with an aromatic ring, or an alkoxyl group having 1 to 8 carbon atoms. .

Specific examples of such phenothiazine derivatives include 2 -methoxyphenothiazine, 4-methoxyphenothiazine, monooctylphenothiazine, dioctylphenothiazine, dibutylphenothiazine, and styrenated phenothiazine. Among these, dioctylphenothiazine, 2-methoxyphenothiazine, dibutylphenothiazine, monooctylphenothiazine, and styrenated phenothiazine are more preferable.

The content of the phenothiazine derivative is preferably 0.5 to 3.0 parts by mass, more preferably 0.75 to 2.5 parts by mass, with respect to 100 parts by mass of the acrylic rubber. It is especially preferable that it is -2.0 mass parts. When the content of the phenothiazine derivative is less than 0.5 parts by mass, a synergistic effect due to the inclusion of a plurality of anti-aging agents may not be obtained. On the other hand, if it exceeds 3.0 parts by mass, the effect is not affected even if the amount is increased further, and the economy may be inferior.

3 Additives The heat-resistant acrylic rubber composition of the present invention comprises a crosslinking agent, a crosslinking accelerator, a reinforcing agent, a processing aid, a light stabilizer, a plasticizer, a lubricant, an adhesive, a lubricant, a flame retardant, You may contain additives, such as an antistatic agent, a filler, and a coupling agent.

(Crosslinking agent)
Examples of the crosslinking agent include polyvalent amine compounds (excluding polyvalent tertiary amine compounds described later), polyvalent epoxy compounds, polyvalent isocyanate compounds, aziridine compounds, sulfur compounds, basic metal oxides, and organometallic halides. A conventionally known cross-linking agent usually used for cross-linking of acrylic rubber such as can be used. Among these, polyvalent amine compounds are preferable. Of the polyvalent amine compounds, polyvalent primary amine compounds are particularly preferred.

  Specific examples of the polyvalent primary amine compound include aliphatic divalent primary amine compounds such as hexamethylenediamine, ethylenediamine and cyclohexanediamine; carbamates of aliphatic divalent primary amine compounds such as hexamethylenediamine carbamate and ethylenediamine carbamate; Hexamethylene) triamine, 3,3′-diaminodipropylamine, aliphatic trivalent primary amine compounds such as cyclohexanetriamine; 4,4′-methylenedianiline, m-phenylenediamine, 4,4′-diaminodiphenyl ether, 3 , 4'-diaminodiphenyl ether, 4,4 '-(m-phenylenediisopropylidene) dianiline, 4,4'-(p-phenylenediisopropylidene) dianiline, 2,2'-bis [4- (4-amino Phenoxy) Feni Aromatic divalent primary amine compounds such as propane, 4,4′-diaminobenzanilide, 4,4′-bis (4-aminophenoxy) biphenyl; N, N ′, N ″ -triphenyl-1,3 Examples thereof include aromatic trivalent primary amine compounds such as 5-benzenetriamine, etc. Among these, aliphatic divalent primary amine compounds, carbamates of aliphatic divalent primary amine compounds, and aromatic divalent primary amine compounds include Hexamethylene diamine carbamate, 4,4′-diaminodiphenyl ether, 4,4 ′-(m-phenylenediisopropylidene) dianiline, 4,4 ′-(p-phenylenediisopropylidene) dianiline, 2,2′- Bis [4- (4-aminophenoxy) phenyl] propane is more preferred, and these may be used alone or in combination. It can be used in combination on.

  The content of the crosslinking agent is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 4 parts by mass, and 0.2 to 3 parts by mass with respect to 100 parts by mass of the acrylic rubber. It is particularly preferred. If the content of the crosslinking agent is less than 0.05 parts by mass, the strength and heat resistance of the heat-resistant acrylic rubber composition may be significantly reduced. On the other hand, if it exceeds 5 parts by mass, the heat-resistant acrylic rubber composition may become too hard, the elongation may decrease, or the elongation after heat aging may be inferior.

(Crosslinking accelerator)
Although it does not specifically limit as a crosslinking accelerator, For example, there exist a guanidine compound, an imidazole compound, a quaternary onium salt, a polyvalent tertiary amine compound, a tertiary phosphine compound, an alkali metal salt of weak acid, etc.

  Specific examples of the guanidine compound include 1,3-diphenylguanidine and 1,3-di-o-tolylguanidine. Specific examples of the imidazole compound include 2-methylimidazole and 2-phenylimidazole. Specific examples of the quaternary onium salt include tetra n-butylammonium bromide and octadecyltri n-butylammonium bromide. Specific examples of the polyvalent tertiary amine compound include triethylenediamine and 1,8-diaza-bicyclo [5.4.0] undecene-7. Specific examples of the tertiary phosphine compound include triphenylphosphine and tri-p-tolylphosphine. Specific examples of the weak acid alkali metal salt include inorganic weak acid salts such as sodium or potassium phosphates or carbonates; organic weak acid salts such as sodium or potassium stearates or laurates.

  The content of the crosslinking accelerator is preferably 0.1 to 20 parts by mass, more preferably 0.2 to 15 parts by mass, and 0.3 to 10 parts by mass with respect to 100 parts by mass of the acrylic rubber. It is particularly preferred that When the content of the crosslinking accelerator is less than 0.1 parts by mass, the tensile strength of the heat-resistant acrylic rubber composition may be significantly reduced, or the elongation or tensile strength after heat aging may be extremely inferior. . On the other hand, if it exceeds 20 parts by mass, the crosslinking rate becomes too fast, the bloom of the crosslinking accelerator on the surface of the heat-resistant acrylic rubber composition occurs, or the heat-resistant acrylic rubber composition becomes too hard. There is.

  In preparing the heat-resistant acrylic rubber composition of the present invention, conventionally known kneading methods such as roll kneading, Banbury kneading, screw kneading, and solution kneading can be employed. The kneading order is not particularly limited, but it is preferable to knead a component that is not easily decomposed by heat before kneading a component that easily reacts with heat or a component that easily decomposes.

  A rubber product using the heat-resistant acrylic rubber composition of the present invention can be produced by appropriately molding or crosslinking the heat-resistant acrylic rubber composition. The molding method is not particularly limited, and can be performed using a conventionally known molding method such as compression molding, injection molding, transfer molding, extrusion molding or the like. Moreover, what is necessary is just to select the crosslinking method according to the shape etc. of a heat resistant acrylic rubber composition, and it may carry out with any of the method of forming and bridge | crosslinking simultaneously, and the method of performing crosslinking after shaping | molding.

  The crosslinking conditions are not particularly limited, and the crosslinking can be performed preferably by heating at a temperature of 130 to 220 ° C, more preferably 140 to 200 ° C, and preferably 30 seconds to 5 hours. As a heating method, a method usually used for crosslinking of rubber such as press heating, steam heating, oven heating, hot air heating and the like may be appropriately selected. In addition, after crosslinking once, in order to ensure crosslinking to the inside of the crosslinked product, crosslinking may be performed after heating over time. Post-crosslinking is preferably performed for 1 to 48 hours, although it varies depending on the heating method, crosslinking temperature, shape, and the like.

  Since the rubber product thus produced is produced using the heat-resistant acrylic rubber composition of the present invention, it is excellent in heat resistance (particularly heat resistance when exposed to high temperature for a long time). Is. Therefore, taking advantage of such characteristics, it can be suitably used as a material for members of transport machines such as automobiles, construction machines, general equipment, electrical equipment, and general industrial machines. Moreover, it can be suitably used as a material for sealing parts such as hoses / tubes, gaskets / packings, and vibration-proof rubber parts.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified. Moreover, the measuring method of various physical-property values and the evaluation method of various characteristics are shown below.

  [Tensile strength (MPa)]: Measured according to JIS K-6251.

  [Elongation (%)]: Measured according to JIS K-6251.

  [Hardness (Duro A)]: Measured according to JIS K-6253.

  [Compression set rate (%)]: In accordance with JIS K-6262, with a cylindrical test piece being compressed by 25%, it was allowed to stand in an environment of 175 ° C. for 70 hours, and then the compression was released. It measured using the test piece. The smaller the compression set, the better the compression set resistance.

Example 1
1 part of stearic acid, 60 parts of carbon black ("Asahi # 60", manufactured by Asahi Carbon Co.), 100 parts of acrylic rubber ("AR-12", manufactured by Nippon Zeon), plasticizer ("Adekasizer RS-") 735 ", manufactured by ADEKA), and 1 part of processing aid (" Greg G-8205 ", manufactured by Dainippon Ink, Inc.) are kneaded with a 1.7 L Banbury mixer and two rolls with a diameter of about 20 cm. An unvulcanized rubber composition was obtained. To the obtained unvulcanized rubber composition, 1 part of p, p'-dicumyldiphenylamine, 1 part of dioctylphenothiazine, di-o-tolylguanidine ("Sunceller DT", manufactured by Sanshin Chemical Industry Co., Ltd.) as a vulcanization accelerator. ) After adding 2 parts and 0.6 part of hexamethylenediamine carbamate ("Diak # 1", manufactured by DuPont) as a vulcanizing agent, kneading was performed, followed by vulcanization with a press vulcanizer and a gear oven. And a sample of a heat resistant acrylic rubber composition was prepared. The sample of the prepared heat-resistant acrylic rubber composition had a tensile strength of 10.1 MPa, an elongation of 200%, a hardness (Duro A) of 61, and a compression set of 12%. In addition, a sample of the heat-resistant acrylic rubber composition prepared was subjected to heat aging test at 175 ° C. for 1000 hours using a forced circulation air heating aging tester (gear oven method) in accordance with JIS K-6257. Went. The elongation of the sample after the heat aging test was 140%.

(Examples 2-8 and Comparative Examples 1-6)
A sample of each heat-resistant acrylic rubber composition was prepared in the same manner as in Example 1 except that the formulation shown in Table 1 was used. Moreover, the heat aging test was done with respect to the sample of each prepared heat resistant acrylic rubber composition, and the elongation of the sample after a heat aging test was also measured. The results are also shown in Table 1.

  As can be seen from Table 1, when the heat-resistant acrylic rubber composition of the present invention containing two types of anti-aging agents, a diphenylamine derivative and a phenothiazine derivative, is used, the residual elongation is excellent even after the heat aging test. Moreover, from the results of Examples 3 and 4, when the content of the phenothiazine derivative is less than 0.5 part, it is expected that the residual elongation after the heat aging test is extremely inferior. Furthermore, from the results of Examples 2 and 7, it is expected that the residual elongation after the heat aging test is remarkably inferior when the content of the diphenylamine derivative is less than 0.5 part. In addition, from the results of Examples 5, 6, and 8, even if the contents of the phenothiazine derivative and the diphenylamine derivative are each more than 3 parts, the effect of the residual elongation after the heat aging test is not imparted. is expected.

(Examples 9 to 12)
Samples of each heat-resistant acrylic rubber composition were prepared in the same manner as in Example 1 except that the formulation shown in Table 2 was used. Moreover, the heat aging test was done with respect to the sample of each prepared heat resistant acrylic rubber composition, and the elongation of the sample after a heat aging test was also measured. The results are also shown in Table 2.

  As can be seen from Table 2, the heat-resistant acrylic rubber composition of the present invention can produce a rubber product having excellent residual elongation even after the heat aging test, regardless of the type of phenothiazine derivative.

(Examples 13-15 and Comparative Examples 7-9)
Samples of each heat-resistant acrylic rubber composition were prepared in the same manner as in Example 1 except that the formulation shown in Table 3 was used. Moreover, the heat aging test was done with respect to the sample of each prepared heat resistant acrylic rubber composition, and the elongation of the sample after a heat aging test was also measured. The results are also shown in Table 3.

  As can be seen from Table 3, the heat-resistant acrylic rubber composition of the present invention has a heat aging as compared with the case where the heat-resistant acrylic rubber composition containing each diphenylamine derivative alone is used regardless of the type of diphenylamine derivative. The residual elongation after the test is excellent.

  The heat-resistant acrylic rubber composition of the present invention exhibits superior performance in heat resistance, particularly high temperature and long-term heat resistance, as compared with the case where a conventional antioxidant or antioxidant is used. Therefore, it can be suitably used as a material for members such as automobiles that require higher heat resistance. It can also be suitably used as a material for hose parts, seal parts, vibration-proof rubber parts and the like that require higher heat resistance.

Claims (1)

An acrylic rubber, and a plurality of antioxidants including a diphenylamine derivative represented by the following general formula (1) and a phenothiazine derivative represented by the following general formula (2) ,
The heat resistant acrylic rubber composition whose total content of the said anti-aging agent is 1.0-6.0 mass parts with respect to 100 mass parts of said acrylic rubber.

(In the general formula (1), R ¹ and R ² are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 18 carbon atoms which may be substituted with an aromatic ring. Is shown.)

(In the general formula (2), R ³ and R ⁴ are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 18 carbon atoms which may be substituted with an aromatic ring, Or an alkoxyl group having 1 to 8 carbon atoms, provided that at least one of R ³ and R ⁴ is a linear or branched alkyl group having 1 to 18 carbon atoms which may be substituted with an aromatic ring. Or an alkoxyl group having 1 to 8 carbon atoms.)