Crosslinkable acrylic rubber composition

Abstract

To provide a crosslinkable acryl rubber composition that suppresses an obvious softening degradation at the initial stage of thermo-oxidative degradation of crosslinked acryl rubber, minimizes the decline in its mechanical strength, allows easy control of crosslinking rates and mechanical strength in the crosslinked products, and exhibits excellent compression set resistance.SOLUTION: A crosslinkable acryl rubber composition includes (A) an acryl rubber containing a carbamate group and a carboxyl group, (B) a polyvalent amine crosslinker and (C) a crosslinking promoter. The acryl rubber can undergo crosslinking without the addition of the commonly used polyvalent amine crosslinker.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a crosslinkable acrylic rubber composition, and more particularly to a crosslinkable acrylic rubber composition that suppresses deterioration in mechanical properties of a crosslinked product due to thermal oxidative degradation and has excellent compression set resistance. [Background technology]

[0002] From the perspective of global climate change countermeasures and efficient energy use, regulations on emissions of carbon dioxide, NOx gases, and other gases emitted by internal combustion engines, such as automobile engines, are becoming increasingly strict. As a response, automobile engines are required to have higher output, higher thermal efficiency, and reduced and harmless exhaust gases, which has resulted in a tendency for temperatures inside the engine compartment to rise. Accordingly, polymeric materials used in the vicinity, such as rubber and plastics, are required to have even greater heat resistance.

[0003] As a specific example, vehicles equipped with turbocharger systems to improve engine fuel efficiency are becoming more common. The air guided from the turbocharger to the intercooler and engine is at high temperature and pressure, so the rubber hose material that transports this air must have high heat resistance.

[0004] As a result of the demand for higher temperatures and longer life for the polymeric materials used in automobile engines, measures have been taken to address these demands, such as improving the heat resistance of the raw rubber material itself used in rubber product components, and adding appropriate antioxidants to rubber product components.

[0005] Typical antioxidants used for rubber members include phenol-based antioxidants and amine-based antioxidants, and amine-based antioxidants are used particularly for rubber members used in higher temperature environments.

[0006] For example, in the case of acrylic rubber, an amine-based antioxidant, typified by 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, is used as the antioxidant (Patent Documents 1 to 4).

[0007] In addition, in an effort to improve the heat resistance of acrylic rubber itself, the crosslinking site monomer has been changed from an active chlorine-containing unsaturated monomer to an α,β-unsaturated carboxylic acid monomer, thereby forming a strong crosslinked structure that can withstand use in high-temperature environments.

[0008] However, even with the improvement of the heat resistance of the raw rubber itself and the addition of amine-based antioxidants, it is not possible to fully satisfy the current demand for heat resistance.

[0009] In recent years, Patent Document 5 describes that phenothiazine-based antioxidants are effective as antioxidants for rubber materials.

[0010] Patent Document 5 describes a rubber material that is excellent in vulcanization properties, mechanical properties, and heat aging properties and is particularly suitable for use as a vibration-proof rubber, and that contains (A) a diene rubber, (B) a bismaleimide compound, and (C) the following phenothiazine compound. TIFF0007791741000001.tif27165R 1 , R 2 : Hydrogen atom, optionally substituted with an aromatic ring C1 to C8 alkyl groups and alkoxy groups, Halogen atoms, cyano groups R 3 : a hydrogen atom, a C1-C6 linear or cyclic alkyl group, vinyl group, aromatic group m, n: 0 to 2 Phenothiazine compounds in which the sulfur atom at the 5-position is -SO2- are also known and are described in, for example, Patent Document 6.

[0011] Patent Document 6 describes a fused heterocyclic compound represented by the following general formula and an organic material composition containing the same, and states that it is possible to impart high processing stability, heat resistance, and long life to organic materials such as polymers that are susceptible to oxidative, thermal, or light-induced degradation. TIFF0007791741000002.tif28165Y: Chemical single bond, -S(=O)-, -SO2- R a , R b : C1 to C which may have a substituent 30 organic group Z a , Z b : Chemical single bond, -SO2- X 1 , X 2 : a hydrogen atom, a halogen atom, an alkyl group, a cyano group, Nitro group, -OR 1 , -O-CO-R 1 , -CO-OR 1 , -O-CO-OR 1 , -NR 2 R 3 , -NR 2 -CO-R 1 , -CO-NR 2 R 3 , -O-CO-NR 2 R 3 n, m: 0 to 2, but either one is not 0

[0012] Furthermore, in order to prevent the volatilization of amine-based antioxidants from rubber components, studies have been conducted to increase the molecular weight and melting point of the amine-based antioxidants. However, as the molecular weight and melting point of the antioxidant increase, problems arise, such as a decrease in dispersibility in rubber and migration within the rubber.

[0013] In order to prevent the volatilization of antioxidants and extend the life of rubber parts in high-temperature environments, a method of copolymerizing antioxidants having polymerizable unsaturated groups with raw rubber has also been investigated (Patent Document 7).

[0014] For example, Non-Patent Documents 1 and 2 exemplify anti-aging agents having a polymerizable unsaturated group, such as Nocrac G-1 (Ouchi Shinko Chemical Industry Co., Ltd.) and APMA (Seiko Chemical Industry Co., Ltd.). TIFF0007791741000003.tif50168

[0015] However, the radical copolymerization of the above antioxidants with polymerizable unsaturated monomers is practically difficult due to the radical polymerization inhibiting effect of the diphenylamino group.

[0016] Additionally, several methods have been disclosed for introducing diphenylamino structures into elastomeric polymers by modification reactions. For example, a method is known in which the side chains of an elastomer having olefinic unsaturated groups are hydroformylated, followed by the introduction of diphenylamino groups (Patent Document 8), and a method is known in which maleic anhydride is added to a diene copolymer in the presence of a free radical generator, followed by the introduction of diphenylamino groups (Patent Document 9). However, these methods require an additional modification step of introducing diphenylamino groups after the production of the base copolymer, making them impractical in terms of production costs.

[0017] Furthermore, a method of crosslinking acrylic rubber in the presence of 4-aminodiphenylamine is known (Patent Document 10), but there is a concern that this method may deteriorate compression set resistance, and its use is therefore limited.

[0018] As described above, it has been difficult with conventional techniques to fully satisfy the current demand for heat resistance, whether by improving the heat resistance of the raw rubber itself, improving the performance of various antioxidants, or chemically bonding a heat-aging prevention component to the raw rubber. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] Japanese Patent Application Publication No. 11-21411 [Patent Document 2] WO 2011 / 58918 A1 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-254579 [Patent Document 4] WO 2006 / 001299 A1 [Patent Document 5] JP 2015-227402 A [Patent Document 6] WO 2011 / 093443 A1 [Patent Document 7] Japanese Patent Application Laid-Open No. 2009-209268 [Patent Document 8] Japanese Patent Application Publication No. 4-264106 [Patent Document 9] Japanese Patent Application Publication No. 5-230132 [Patent Document 10] WO 2020 / 158132 A1 [Patent Document 11] JP 2009-036960 A [Patent Document 12] JP 2010-235955 A [Patent Document 13] Patent Publication No. 2020-111552 [Non-patent literature]

[0020] [Non-Patent Document 1] Rubber Chem. Technol., Vol. 46, p. 106 (1973) [Non-patent document 2] Rubber Chem. Technol., Vol. 52, p. 883 (1979) [Non-patent document 3] Journal of Photopolymer Science and Technology, Vol. 18, No. 3, p. 419 (2005) [Non-patent document 4] Material Technology, Vol. 25, No. 6, p. 285 (2007)

[0021] To address the above issues, the applicant has previously proposed a cross-linkable acrylic rubber composition (Japanese Patent Application No. 2021-133264) consisting of an acrylic rubber containing carbamate groups and carboxyl groups, an amine-based antioxidant, and a cross-linking accelerator. This composition can suppress the significant softening and deterioration observed in the early stages of thermal oxidative degradation of acrylic rubber, which is primarily made from ethyl acrylate.

[0022] However, the above crosslinkable acrylic rubber composition still has room for further improvement in terms of control of the crosslinking rate, control of the mechanical strength of the crosslinked product, and resistance to compression set. Summary of the Invention [Problem to be solved by the invention]

[0023] The present invention has been made in view of the above-mentioned problems, and provides a cross-linkable acrylic rubber composition that suppresses the significant softening and deterioration observed in the early stage of thermo-oxidative deterioration of a cross-linked acrylic rubber product, minimizes the decrease in mechanical strength, makes it easy to control the cross-linking rate and the mechanical strength of the cross-linked product, and furthermore, has excellent resistance to compression set. [Means for solving the problem]

[0024] in particular (A) Acrylic rubber containing carbamate ester groups and carboxyl groups (C) Crosslinking accelerator A crosslinkable acrylic rubber composition comprising (B) Polyamine crosslinker The above problem is solved by adding [Effects of the Invention]

[0025] When crosslinking acrylic rubber containing carbamate ester groups and carboxyl groups, the carbamate ester groups are decomposed by the action of heat and a crosslinking accelerator, liberating amino groups, which then react with active sites derived from the α,β-unsaturated carboxylic acid monomer to form a unique crosslinked structure. In this way, acrylic rubber containing carbamate ester groups and carboxyl groups can be crosslinked without adding the commonly used polyamine crosslinking agent, and the resulting crosslinked acrylic rubber exhibits the effect of suppressing significant softening and degradation in the early stages of thermooxidative degradation.

[0026] The present inventors have discovered that by adding a polyamine crosslinking agent to a crosslinkable composition comprising an acrylic rubber containing a carbamate group and a carboxyl group and a crosslinking accelerator, it is possible to easily control the crosslinking rate and the mechanical strength of the crosslinked product without impairing the thermal oxidative degradation resistance, and furthermore, to improve compression set resistance.

[0027] Incidentally, (meth)acrylate copolymers containing carbamic acid ester groups are described in Patent Document 11 and Non-Patent Documents 3 and 4, and furthermore, Patent Document 12 describes that carboxyl group-containing acrylic rubber can be crosslinked using a dicarbamic acid ester compound. [Brief explanation of the drawings]

[0028] [Figure 1] The change over time in hardness of a cross-linked acrylic rubber at 190°C is shown graphically (Example 1: --◆-, Comparative Example 1: --◆--, Example 2: --●-, Comparative Example 2: --●--, Example 3: --▲-, Comparative Example 3: --▲---, Example 4: --■-, Comparative Example 4: --■--; common to Figures 1 to 4). [Figure 2] This is a diagram showing the change over time in the 100% modulus change rate of a cross-linked acrylic rubber at 190°C. [Figure 3] This is a diagram showing the change over time in the rate of change in strength at break of a cross-linked acrylic rubber at 190°C. [Figure 4] This is a diagram showing the change over time in the rate of change in elongation at break of a cross-linked acrylic rubber at 190°C. DETAILED DESCRIPTION OF THE INVENTION

[0029] The crosslinkable acrylic rubber composition of the present invention comprises: (A) Acrylic rubber containing carbamate ester groups and carboxyl groups (B) Polyamine crosslinker and (C) Crosslinking accelerator It consists of:

[0030] The acrylic rubber containing a carbamate group and a carboxyl group as component (A) includes: Mode (A-1): 90 to 99.8% by weight of alkyl (meth)acrylate and / or alkoxyalkyl (meth)acrylate monomer, 0.1 to 5% by weight of an α,β-unsaturated carboxylic acid monomer, and a copolymer of the general formula [I] TIFF0007791741000004.tif39166 (where R 1 is a hydrogen atom or a methyl group, and R 2 (Meth)acrylate monomer containing a carbamate ester group represented by (C1-10 divalent aliphatic hydrocarbon group) and acrylic rubber copolymerized with a monomer ratio of 0.1-5% by weight. or Aspect (A-2): Acrylic rubber (i) copolymerized in a monomer ratio of 90 to 99.9% by weight of alkyl (meth)acrylate and / or alkoxyalkyl (meth)acrylate monomer and 0.1 to 10% by weight of a carbamate group-containing (meth)acrylate monomer represented by general formula [I] and (ii) Acrylic rubber copolymerized with 90 to 99.9% by weight of alkyl (meth)acrylate and / or alkoxyalkyl (meth)acrylate monomer and 0.1 to 10% by weight of α,β-unsaturated carboxylic acid monomer. The weight ratio of each component is 90 to 10% by weight and 10 to 90% by weight. acrylic rubber Here, (meth)acrylate refers to acrylate or methacrylate.

[0031] The (A-1) consisting of a single acrylic rubber is copolymerized in the following monomer ratios: 99.8 to 90% by weight, preferably 99 to 90% by weight, of alkyl (meth)acrylate monomer and / or alkoxyalkyl (meth)acrylate monomer, 0.1 to 5% by weight, preferably 0.5 to 5% by weight, of α,β-unsaturated carboxylic acid monomer, and 0.1 to 5% by weight, preferably 0.5 to 5% by weight, of carbamate group-containing (meth)acrylate monomer.

[0032] The approximate ratio of the weight fraction composition of the carbamate group-containing (meth)acrylate monomer and the weight fraction composition of the α,β-unsaturated carboxylic acid monomer in the acrylic rubber of embodiment (A-1) is w CA / M CA ≧w NH2 / M NH2 These ratios can be adjusted appropriately taking into consideration factors such as the crosslinking rate and the physical properties of the crosslinked product. w CA (wt%): Weight fraction composition of α,β-unsaturated carboxylic acid monomer in acrylic rubber M CA (g / mol): Molecular weight of α,β-unsaturated carboxylic acid monomer w NH2 (wt%): Weight fraction composition of carbamate group-containing (meth)acrylate monomer of acrylic rubber M NH2 (g / mol): Molecular weight of carbamate group-containing (meth)acrylate monomer

[0033] Examples of the acrylic rubber of embodiment (A-1) other than those described above include an elastomeric copolymer having as main components ethylene, methyl acrylate, a carbamic acid ester group-containing (meth)acrylate monomer, and an α,β-unsaturated carboxylic acid monomer, or an elastomeric copolymer having as main components ethylene, vinyl acetate, a carbamic acid ester group-containing (meth)acrylate monomer, and an α,β-unsaturated carboxylic acid monomer.

[0034] The acrylic rubber (i) used in embodiment (A-2) consisting of a mixture of acrylic rubbers is a copolymer of 99.9 to 90% by weight, preferably 99.5 to 95% by weight, of alkyl (meth)acrylate monomers and / or alkoxyalkyl (meth)acrylate monomers and 0.1 to 10% by weight, preferably 0.5 to 5% by weight, of carbamate group-containing (meth)acrylate monomers.

[0035] The acrylic rubber (ii) is a copolymer of 99.9 to 90% by weight, preferably 99.5 to 95% by weight, of alkyl (meth)acrylate monomers and / or alkoxyalkyl (meth)acrylate monomers and 0.1 to 10% by weight, preferably 0.5 to 5% by weight, of α,β-unsaturated carboxylic acid monomers. The mixing ratios of the acrylic rubber (i) and the acrylic rubber (ii) are set to 90 to 10% by weight and 10 to 90% by weight, respectively, taking into account the stoichiometric amounts of the carbomic acid ester groups and active sites of the α,β-unsaturated carboxylic acid monomers contained in the mixture.

[0036] The weight ratio of the acrylic rubber (i) and the acrylic rubber (ii) in the acrylic rubber mixture of the embodiment (A-2) is roughly as follows: W (i) ×w (i)NH2 / M (i)NH2 ≦W (ii) ×w (ii)CA / M (ii)CA These ratios can be adjusted appropriately taking into consideration factors such as the crosslinking rate and the physical properties of the crosslinked product. W (i) (Parts by weight): Weight of acrylic rubber (i) w (i)NH2 wt%): Carbamate group-containing (meth)acrylate of acrylic rubber (i) Monomer weight fraction composition M (i)NH2 (g / mol): Molecular weight of carbamate group-containing (meth)acrylate monomer W (ii) (Parts by weight): Weight of acrylic rubber (ii) w (ii)CA(wt%): Weight fraction composition of α,β-unsaturated carboxylic acid monomer in acrylic rubber (ii) M (ii)CA (g / mol): Molecular weight of α,β-unsaturated carboxylic acid monomer

[0037] The acrylic rubber mixture (A-2) can be easily prepared by mixing the acrylic rubber (i) and the acrylic rubber (ii) using an open roll, a kneader, a Banbury mixer, or the like.

[0038] Alternatively, a desired acrylic rubber mixture can be prepared by mixing an aqueous latex of the acrylic rubber (i) and an aqueous latex of the acrylic rubber (ii) in any desired ratio, followed by coagulation with an aqueous electrolyte solution and drying.

[0039] Examples of the acrylic rubber (i) other than those mentioned above include elastomeric copolymers having ethylene, methyl acrylate, and a carbamate group-containing (meth)acrylate monomer as the main components, and elastomeric copolymers having ethylene, vinyl acetate, and a carbamate group-containing (meth)acrylate monomer as the main components.

[0040] As the acrylic rubber (ii) other than those mentioned above, for example, an elastomeric copolymer having ethylene, methyl acrylate and an α,β-unsaturated carboxylic acid monomer as the main components, or an elastomeric copolymer having ethylene, vinyl acetate and an α,β-unsaturated carboxylic acid monomer as the main components, can be used.

[0041] The monomers constituting the single acrylic rubber of embodiment (A-1) and the acrylic rubbers (i) and (ii) of embodiment (A-2) are as follows:

[0042] The alkyl(meth)acrylate monomer and / or alkoxyalkyl(meth)acrylate monomer that is the monomer unit of the acrylic rubber of embodiment (A-1) and the acrylic rubber (i) and (ii) of embodiment (A-2) is at least one (meth)acrylate selected from alkyl(meth)acrylates having an alkyl group with 1 to 8 carbon atoms, aralkyl(meth)acrylates having an aralkyl group with 7 to 20 carbon atoms, and alkoxyalkyl(meth)acrylates having an alkoxyalkyl group with 2 to 8 carbon atoms.

[0043] Examples of alkyl(meth)acrylates that can be used include methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, n-hexyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, n-octyl(meth)acrylate, and cyclohexyl(meth)acrylate.

[0044] As the aralkyl(meth)acrylate, for example, benzyl(meth)acrylate is used.

[0045] Examples of alkoxyalkyl (meth)acrylates that can be used include methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, n-butoxyethyl (meth)acrylate, ethoxypropyl (meth)acrylate, methoxyethoxyethyl (meth)acrylate, and ethoxyethoxyethyl (meth)acrylate.

[0046] In addition to the main components (monomers) of the acrylic rubber of embodiment (A-1) and the acrylic rubbers (i) and (ii) of embodiment (A-2), the following polymerizable unsaturated monomers can be used as secondary components, if necessary.

[0047] Examples of the polymerizable unsaturated monomer include styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, acrylonitrile, methacrylonitrile, acrylic acid amide, vinyl acetate, methyl vinyl ether, ethyl vinyl ether, ethylene, propylene, piperylene, butadiene, isoprene, chloroprene, cyclopentadiene, vinyl chloride, and vinylidene chloride.

[0048] Specific examples of the carbamate ester-containing (meth)acrylate monomer represented by general formula [I], which is the monomer unit of the acrylic rubber of embodiment (A-1) and the acrylic rubber (i) of embodiment (A-2), include: TIFF0007791741000005.tif115168, etc., are preferred from the viewpoint of ease of production. TIFF0007791741000006.tif30168 is used.

[0049] The carbamate group-containing (meth)acrylate monomer represented by general formula [I] can be easily produced by reacting an isocyanatoalkyl acrylate or an isocyanatoalkyl (meth)acrylate with 9-fluorenylmethanol in the presence of a urethanization reaction catalyst.

[0050] As the urethanization reaction catalyst, an organotin compound, an organotitanium compound, an organozirconium compound, an organobismuth compound, or the like can be used.

[0051] Examples of the organotin compound include dibutyltin dilaurate, tin bis(2-ethylhexanoate), and dibutyltin(2,4-pentanedionate).

[0052] Examples of organic titanium compounds include titanium diisopropoxybis(ethylacetoacetate).

[0053] Examples of organic zirconium compounds include zirconium dibutoxybis(ethyl acetate) and zirconium tetra(acetyl acetate).

[0054] Examples of organic bismuth compounds include bismuth tris(neodecanoate).

[0055] The reaction is carried out in an organic solvent such as benzene, toluene, dioxane, methyl ethyl ketone, or cyclohexane at a temperature of 40 to 80°C.

[0056] Examples of the α,β-unsaturated carboxylic acid monomer that is the monomer unit of the acrylic rubber of embodiment (A-1) and the acrylic rubber (ii) of embodiment (A-2) include monobasic α,β-unsaturated carboxylic acid, dibasic α,β-unsaturated carboxylic acid, and dibasic α,β-unsaturated carboxylic acid monoalkyl ester.

[0057] Examples of the monobasic α,β-unsaturated carboxylic acid include acrylic acid and methacrylic acid.

[0058] Examples of the dibasic α,β-unsaturated carboxylic acid include maleic acid, maleic anhydride, fumaric acid, itaconic acid, and citraconic acid.

[0059] Examples of dibasic α,β-unsaturated carboxylic acid monoalkyl esters include monoalkyl esters of maleic acid, fumaric acid, itaconic acid, and citraconic acid. Specific examples include monomethyl maleate, monoethyl maleate, mono-n-propyl maleate, monoisopropyl maleate, mono-n-butyl maleate, monoisobutyl maleate, mono-n-hexyl maleate, monocyclohexyl maleate, monomethyl fumarate, monoethyl fumarate, mono-n-propyl fumarate, monoisopropyl fumarate, mono-n-butyl fumarate, monoisobutyl fumarate, mono-n-hexyl fumarate, and monocyclohexyl fumarate.

[0060] The acrylic rubber of embodiment (A-1) and the acrylic rubbers (i) and (ii) of embodiment (A-2) are produced by a general acrylic rubber polymerization method. The copolymerization reaction can be carried out by any method, such as emulsion polymerization, suspension polymerization, solution polymerization, or bulk polymerization, but is preferably carried out by emulsion polymerization or suspension polymerization at a temperature of about -10 to 100°C, preferably about 5 to 80°C.

[0061] As the polymerization initiator for the reaction, organic peroxides or hydroperoxides such as benzoyl peroxide, dicumyl peroxide, tert-butyl hydroperoxide, cumyl hydroperoxide, and p-methylene hydroperoxide, diazo compounds such as azobisisobutyronitrile and azobisisobutylamidine, and peroxide salts such as ammonium salts typified by ammonium persulfate, sodium salts, and potassium salts may be used alone or as redox initiators.

[0062] A particularly preferred emulsifier for use in emulsion polymerization is an aqueous solution of an anionic or nonionic surfactant, the pH of which is adjusted with an acid or base as necessary, and which is buffered with an inorganic salt.

[0063] The polymerization reaction is continued until the conversion rate of the monomer mixture reaches 90% or more. The obtained aqueous latex is coagulated by a salt-acid coagulation method, a method using a salt such as calcium chloride, magnesium sulfate, sodium sulfate, or ammonium sulfate, a method using a boron compound such as boric acid or borax, a thermal coagulation method, or a freeze coagulation method, and the obtained copolymer is thoroughly washed with water and dried. This acrylic rubber has a Mooney viscosity (PML) of about 5 to 100, preferably about 20 to 80. 1+4 (100°C).

[0064] Component (B), which is a constituent of the composition of the present invention, can be an aliphatic polyamine compound, a carbonate of an aliphatic polyamine compound, an aliphatic polyamine compound in which the amino group is protected with an organic group, or an aromatic polyamine compound.

[0065] Examples of aliphatic polyamine compounds include hexamethylenediamine. Examples of carbonates of aliphatic polyamine compounds include hexamethylenediamine carbamate. Examples of aliphatic polyamines in which amino groups are protected with organic groups include N,N'-dicinnamylidene-1,6-hexanediamine and the compounds disclosed in Patent Document 12.

[0066] Examples of aromatic polyvalent amine compounds include 4,4'-methylenedianiline, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-bis(4-aminophenoxy)biphenyl, m-xylylenediamine, p-xylylenediamine, 1,3,5-benzenetriamine, 4,4'-(m-phenylenediisopropylidene)dianiline, 4,4'-(p-phenylenediisopropylidene)dianiline, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 4,4'-diaminobenzanilide.

[0067] The polyamine compounds listed above can be used alone or in combination of two or more, and preferably, hexamethylenediamine carbamate, 4,4'-diaminodiphenyl ether, and 2,2-bis[4-(4-aminophenoxy)phenyl]propane are used.

[0068] The amount of polyamine crosslinking agent (B) added is adjusted appropriately depending on the desired crosslinking rate, mechanical strength of the crosslinked product, resistance to compression set, and resistance to thermal oxidation degradation. It is used in an amount of about 0.01 to 5 parts by weight, preferably about 0.05 to 3 parts by weight, per 100 parts by weight of acrylic rubber (A). If the amount of polyamine crosslinking agent is less than this amount, no improvement in resistance to compression set can be expected. On the other hand, if more than this amount is used, the resistance to thermal oxidation degradation of the acrylic rubber may be deteriorated.

[0069] Component (C) Examples of the crosslinking accelerator include guanidine compounds, diazabicycloalkene compounds, and organic acid salts thereof.

[0070] Examples of the guanidine compound include tetramethylguanidine, tetraethylguanidine, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, etc. Preferred are 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, or a combination thereof.

[0071] The diazabicycloalkene compound is preferably 1,8-diazabicyclo[5.4.0]-7-undecene.

[0072] The organic acid salt of the diazabicycloalkene compound is preferably an organic acid salt of 1,8-diazabicyclo[5.4.0]-7-undecene.

[0073] The organic acid used for the organic acid salt of 1,8-diazabicyclo[5.4.0]-7-undecene includes an organic monobasic acid or an organic dibasic acid.

[0074] Examples of organic monobasic acids include n-hexanoic acid, n-heptanoic acid, n-octanoic acid, 2-ethylhexanoic acid, n-capric acid, n-lauric acid, p-toluenesulfonic acid, phenol, etc. Examples of organic dibasic acids include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, terephthalic acid, orthophthalic acid, phthalic acid, etc., and monocarboxylic or dicarboxylic acids having 6 to 18 carbon atoms are preferred.

[0075] The crosslinking accelerator (C) is used in an amount of about 0.1 to 5 parts by weight, preferably about 0.3 to 3 parts by weight, per 100 parts by weight of the acrylic rubber (A). Less than this amount of crosslinking accelerator may result in a significant decrease in the crosslinking rate, a decrease in the mechanical properties of the acrylic rubber after crosslinking, and a decrease in the mechanical properties after heat aging. On the other hand, if more than this amount is used, the acrylic rubber may be subject to deterioration in its resistance to thermal oxidation degradation or compression set.

[0076] The crosslinkable acrylic rubber composition of the present invention may be blended with various additives, as needed, such as an antioxidant, a filler, a processing aid, a plasticizer, a softener, a colorant, a stabilizer, an adhesion aid, a release agent, an electrical conductivity imparting agent, a thermal conductivity imparting agent, a surface non-stick agent, a tackifier, a flexibility imparting agent, a heat resistance improver, a flame retardant, an ultraviolet absorber, an oil resistance improver, a scorch inhibitor, and a lubricant.

[0077] Amine-based antioxidants are commonly used, and a representative example is 4,4'-bis(α,α-dimethylbenzyl)diphenylamine.

[0078] When resistance to thermal oxidative deterioration in a higher temperature environment is required, a phenothiazine-based antioxidant is preferred. For example, a phenothiazine-based antioxidant represented by the following general formula [II] can be mentioned. TIFF0007791741000007.tif38169 (where R 3 represents a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or a group represented by the following general formula [III]: TIFF0007791741000008.tif27169 is an acyl group, where R 4 is a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms. R 5 is an aralkyl group having 7 to 20 carbon atoms.

[0079] R 3Specific examples of when is an aliphatic hydrocarbon group having 1 to 20 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-undecyl group, an n-pentadecyl group, an n-heptadecyl group, an isopropyl group, a 2-butyl group, a 2-pentyl group, a 3-pentyl group, a 2-hexyl group, a 3-hexyl group, a 2-heptyl group, a 3-heptyl group, a 4-heptyl group, a 2-octyl group, a 3-octyl group, a 4-octyl group, a Examples of the alkyl group include a tert-butyl group, a 1,1-dimethyl-1-propyl group, a 1,1-dimethyl-1-butyl group, a 1,1-dimethyl-1-pentyl group, a 1,1-dimethyl-1-hexyl group, a 3-methyl-3-pentyl group, a 3-ethyl-3-pentyl group, a 3-methyl-3-hexyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a 1-methyl-1-cyclopentyl group, a 1-methyl-1-cyclohexyl group, and a 1-adamantyl group.

[0080] R 3 When is an aralkyl group having 7 to 20 carbon atoms, specific examples include a benzyl group, an α-methylbenzyl group, and a 9-fluorenylmethyl group.

[0081] R 4Examples of the monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-undecyl group, an n-pentadecyl group, an n-heptadecyl group, an isopropyl group, a 2-butyl group, a 2-pentyl group, a 3-pentyl group, a 2-hexyl group, a 3-hexyl group, a 2-heptyl group, a 3-heptyl group, a 4-heptyl group, a 2-octyl group, a 3-octyl group, a 4-octyl group, a Examples of such alkyl groups include a tert-butyl group, a 1,1-dimethyl-1-propyl group, a 1,1-dimethyl-1-butyl group, a 1,1-dimethyl-1-pentyl group, a 1,1-dimethyl-1-hexyl group, a 3-methyl-3-pentyl group, a 3-ethyl-3-pentyl group, a 3-methyl-3-hexyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a 1-methyl-1-cyclopentyl group, a 1-methyl-1-cyclohexyl group, and a 1-adamantyl group.

[0082] In particular, monovalent aliphatic hydrocarbon groups having 4 to 20 carbon atoms in which the carbon at the α-position relative to the carbonyl group is a tertiary carbon are preferred, and preferred examples thereof include a tert-butyl group, a 1,1-dimethylpropyl group, a 1,1-dimethyl-1-butyl group, a 1,1-dimethyl-1-pentyl group, a 1,1-dimethyl-1-hexyl group, a 3-methyl-3-pentyl group, a 3-ethyl-3-pentyl group, a 3-methyl-3-hexyl group, a 1-methyl-1-cyclopentyl group, a 1-methyl-1-cyclohexyl group, and a 1-adamantyl group.

[0083] R 5 Examples of the aralkyl group represented by the formula (I) include a benzyl group, an α-methylbenzyl group, and an α,α-dimethylbenzyl group, with an α,α-dimethylbenzyl group being particularly preferred.

[0084] R 3A phenothiazine-based antioxidant in which is a hydrogen atom can be produced by the method described in Patent Document 6. For example, phenothiazine is reacted with α-methylstyrene in the presence of an acidic catalyst to form 3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine (hereinafter abbreviated as CD-S), and then the sulfur atom is oxidized with an oxidizing agent to produce 3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide (hereinafter abbreviated as CD-SO2).

[0085] R 3 In the case of a phenothiazine antioxidant in which R is an aliphatic hydrocarbon group having 1 to 20 carbon atoms, the desired phenothiazine antioxidant can be produced by treating CD-S with a base, followed by N-alkylation with a halide of an aliphatic hydrocarbon having 1 to 20 carbon atoms, and then oxidizing the resulting compound. Alternatively, CD-SO2 obtained in Patent Document 6 may be treated with a base, followed by reaction with a halide of an aliphatic hydrocarbon having 1 to 20 carbon atoms.

[0086] R 3 When is an acyl group represented by general formula [III], it can be produced by the method described in Patent Document 13. Specifically, the desired phenothiazine antioxidant can be produced by N-acylation of CD-S with an acyl halide in the presence of a basic organic compound or a basic inorganic compound, followed by oxidation. Alternatively, it can be produced by N-acylation of CD-SO2 using a similar method.

[0087] Specific examples of the phenothiazine-based antioxidant represented by the general formula [II] include: 3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide 10-methyl-3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide 10-Propyl-3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide 10-Isopropyl-3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide 10-benzyl-3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide 10-Pivaloyl-3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide 10-(2,2-dimethyl-butanoyl)-3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide 10-(1-Adamantanecarbonyl)-3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide etc.

[0088] Examples of fillers include silica such as basic silica and acidic silica, metal oxides such as zinc oxide, calcium oxide, titanium oxide and aluminum oxide; metal hydroxides such as magnesium hydroxide, aluminum hydroxide and calcium hydroxide; carbonates such as magnesium carbonate, aluminum carbonate, calcium carbonate and barium carbonate; silicates such as magnesium silicate, calcium silicate, sodium silicate and aluminum silicate; sulfates such as aluminum sulfate, calcium sulfate and barium sulfate; metal sulfides such as molybdenum disulfide, iron sulfide and copper sulfide; synthetic hydrotalcite, diatomaceous earth, asbestos, lithopone (zinc sulfide / barium sulfide), graphite, carbon black (MT carbon black, SRF carbon black, FEF carbon black, etc.), carbon fluoride, calcium fluoride, coke, quartz fine powder, zinc oxide, talc, mica powder, wollastonite, carbon fiber, aramid fiber, various whiskers, glass fiber, organic reinforcing agents, and organic fillers.

[0089] Examples of processing aids include higher fatty acids such as stearic acid, oleic acid, palmitic acid, and lauric acid; higher fatty acid salts such as sodium stearate and zinc stearate; higher fatty acid amides such as stearic acid amide and oleic acid amide; higher fatty acid esters such as ethyl oleate, higher aliphatic amines such as stearylamine and oleylamine; petroleum waxes such as carnauba wax and ceresin wax; polyglycols such as ethylene glycol, glycerin, and diethylene glycol; aliphatic hydrocarbons such as petrolatum and paraffin; silicone oils, silicone polymers, low-molecular-weight polyethylene, phthalate esters, phosphate esters, rosin, (halogenated) dialkylamines, (halogenated) dialkylsulfones, and surfactants.

[0090] Examples of plasticizers include epoxy resins, phthalic acid derivatives, and sebacic acid derivatives; examples of softeners include lubricating oils, process oils, coal tar, castor oil, and calcium stearate; and examples of antioxidants include phenylenediamines, phosphates, quinolines, cresols, phenols, and dithiocarbamate metal salts.

[0091] The above compounding ingredients, which are used as needed, are blended together with an amine-based antioxidant into the crosslinkable acrylic rubber composition of the present invention, which comprises an acrylic rubber, a crosslinking agent, and a crosslinking accelerator, and mixed using a Banbury mixer, a pressure kneader, an open roll, etc. Crosslinking of the resulting crosslinkable mixture is carried out by primary crosslinking at about 120 to 250°C for about 1 to 60 minutes, and, if necessary, oven crosslinking (secondary crosslinking) at about 120 to 200°C for about 1 to 20 hours. [Example]

[0092] The present invention will now be described in detail with reference to examples, although the present invention, including its effects, is not limited to these examples.

[0093] Reference example 1 Preparation of 3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide [CD-SO2] TIFF0007791741000009.tif4116524.9 g (0.125 mol) of phenothiazine, 0.6 g of p-toluenesulfonic acid, and 115 ml of toluene were placed in a 500 ml four-neck flask equipped with a magnetic stirrer, a thermometer, a nitrogen gas inlet and outlet, and a reflux condenser. The mixture was heated to 80°C, and then 29.5 g (0.25 mol) of α-methylstyrene was added and the mixture was allowed to react for 1 hour under a nitrogen gas atmosphere.

[0094] Next, 30 g of acetic acid was added to the reaction mixture, followed by the addition of 42.5 g of 30% aqueous hydrogen peroxide in five portions, and the reaction was continued at 80°C for another 2 hours. The contents were cooled to room temperature and allowed to stand, after which the upper toluene layer was poured into 500 ml of methanol. After standing overnight at room temperature, 42.5 g (72% yield) of crude CD-SO2 was obtained as pale yellow crystals. This was recrystallized from ethanol to obtain 38 g (65% yield) of CD-SO2 as pale yellow needle crystals.

[0095] Reference example 2 Preparation of 10-pivaloyl-3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide [CD-SO2-PIV] TIFF0007791741000010.tif47166 119.6 g (0.6 mol) of phenothiazine, 2.88 g of p-toluenesulfonic acid, and 480 ml of toluene were placed in a 1000 ml four-neck flask equipped with a magnetic stirrer, a thermometer, a nitrogen gas inlet and outlet, and a reflux condenser. The mixture was heated to 80°C, and then 141.9 g (1.2 mol) of α-methylstyrene was added and the mixture was allowed to react for 1 hour under a nitrogen gas atmosphere.

[0096] After cooling the reaction mixture to room temperature, the toluene was distilled off under reduced pressure to obtain 265.5 g of a purple solid reaction product. This was recrystallized from 1500 ml of ethanol to obtain 179 g (68% yield) of crude 3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine [CD-S] as light reddish-purple crystals. This crude CD-S was further recrystallized from ethanol to obtain 161 g (61% yield) of purified CD-S as colorless, flaky crystals.

[0097] A 500 ml three-neck flask equipped with a magnetic stirrer, thermometer, and reflux condenser was charged with 68.7 g (158 mmol) of crude CD-S, 24.8 g (206 mmol) of pivaloyl chloride, and 60 g of pyridine, sequentially, and the mixture was reacted at 120°C for 1.5 hours. The pyridine was removed from the resulting reaction mixture by distillation under reduced pressure, and the residue was then dissolved in 300 ml of dichloromethane. The organic layer was washed three times with 300 ml of saturated aqueous sodium chloride solution and dried over anhydrous magnesium sulfate. After filtering the magnesium sulfate, the volatile components were removed from the filtrate by distillation under reduced pressure, yielding 81.7 g of a red, highly viscous liquid.

[0098] This highly viscous liquid was dissolved in 250 ml of toluene and placed in a 1000 ml three-necked flask equipped with a magnetic stirrer, a thermometer, and a reflux condenser. 80 g of acetic acid and 107 g of 30% hydrogen peroxide were then added, and the mixture was allowed to react at 100°C for 2 hours.

[0099] After cooling to room temperature, the upper toluene layer was removed and the volatiles were removed under reduced pressure. The resulting pale red solid (89 g) was recrystallized from a 9:1 ethanol / toluene (volume ratio) mixed solvent to obtain 70.3 g (81% yield) of CD-SO2-PIV as colorless needle crystals. 1 H NMR (300MHz, CDCl3, δ ppm): 1.22 (s, 9H, -C(C H 3)3) 1.71 (s, 12H, -C(C H 3)2-) 7.19~7.30 (m, 12H, Ar) 7.42 (d, J=9.0Hz, 2H, Ar) 8.03 (d, J=1.8Hz, 2H, Ar)

[0100] Reference example 3 Preparation of 10-benzyl-3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide [CD-SO2-Bn] TIFF0007791741000011.tif53166 43.6 g (100 mmol) of purified CD-S and 250 ml of N,N-dimethylformamide were placed in a 1000 ml four-neck flask equipped with a magnetic stirrer, thermometer, gas inlet tube, and reflux condenser, and cooled to below 5°C under a nitrogen atmosphere. 3.6 g (150 mmol) of sodium hydride was added while maintaining the temperature below 10°C, and the reaction was continued for 1 hour. 16.4 g (130 mmol) of benzyl chloride was added, and the reaction was continued for 1 hour at 70°C. The resulting reaction mixture was cooled to room temperature and poured into saturated aqueous sodium chloride. The product was extracted with dichloromethane, and the organic layer was dried over anhydrous magnesium sulfate. After filtering off the magnesium sulfate, volatile components were distilled off from the filtrate under reduced pressure to obtain 55.1 g of crude 10-benzyl-3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine [CD-S-Bn] as a slightly yellowish solid.

[0101] 55.1 g of crude CD-S-Bn was dissolved in 500 ml of toluene and placed in a 1000 ml four-neck flask equipped with a magnetic stirrer, a thermometer, and a reflux condenser. 60 g of acetic acid and 68 g of 60% hydrogen peroxide were then added sequentially, and the mixture was allowed to react at 90°C for 2 hours.

[0102] After cooling the contents to room temperature, the upper toluene layer was removed and the volatiles were distilled off under reduced pressure. The resulting red product was recrystallized from toluene to give 48.1 g of CD-SO2-Bn as colorless crystals (86% yield from CD-S). 1 H NMR (400MHz, Acetone d6, δ ppm): 1.74 (s, 12H, -C(C H 3)2-) 5.56 (s, 2H, NC H 2-Ar) 7.15~7.37 (m, 17H, Ar) 7.42(dd, J=8.8Hz, 2.8Hz, 2H, Ar) 7.92 (d, J=2.8Hz, 2H, Ar)

[0103] Reference example 4 9FMM Manufacturing TIFF0007791741000012.tif53166 29.6 g (151 mmol) of 9-fluorenylmethanol, 25.5 g (164 mmol) of 2-isocyanatoethyl methacrylate, 1.1 g of dibutyltin dilaurate, and 440 ml of benzene were placed in a 1000 ml four-neck flask equipped with a magnetic stirrer, a thermometer, a nitrogen gas inlet and outlet, and a reflux condenser, and the mixture was allowed to react at 80°C for 2 hours under a nitrogen gas atmosphere.

[0104] After the reaction mixture was cooled to room temperature, 60 mg of paramethoxyphenol was added, and the benzene was then distilled off under reduced pressure to obtain 55.7 g of crude reaction product, which was recrystallized from 600 ml of ethanol to obtain 44.7 g (84% yield) of 9FMM as colorless crystals. 1 H-NMR (400MHz, Acetone d6, δ ppm): 1.91 (s, 3H, CH2=C(C H 3)-C(=O)-O-) 3.47 (q, J=5.6Hz, 2H, -O-CH2C H 2-NH-C(C=O)-) 4.21 (t, J=5.6Hz, 2H, -OC H 2CH2-NH-C(C=O)-) 4.23 (t, J=7.2Hz, 1H, -C(=O)-OCH2-C H -Ar2) 4.35 (d, J=7.2Hz, 2H, -C(=O)-OCH 2-CH-Ar2) 5.62 (s, 1H, trans-C to carbonyl group H 2=C(CH3)-C(=O)-O-) 6.10 (s, 1H, cis-C relative to carbonyl group H 2=C(CH3)-C(=O)-O-) 6.73 (brs, 1H, -O-CH2CH2-N H -C(C=O)- 7.32 (t, J=7.6Hz, 2H, Ar) 7.41 (t, J=7.6Hz, 2H, Ar) 7.68 (d, J=7.6Hz, 2H, Ar) 7.86 (d, J=7.6Hz, 2H, Ar)

[0105] Reference example 5 [Production of acrylic rubber (a)] In a separable flask equipped with a thermometer, a stirrer, a nitrogen gas inlet tube, and a Dimroth condenser, Water 187 parts by weight Sodium lauryl sulfate 2 〃 Polyoxyethylene lauryl ether 2 Charged monomer mixture Ethyl acrylate (EA) 97.4 % Mono-n-butyl fumarate [MBF] 1.6 〃 9FMM 1.0 〃 After the oxygen in the system was thoroughly removed by nitrogen gas replacement, Sodium formaldehyde sulfoxylate 0.008 parts by weight (Fujifilm Wako Pure Chemical Industries Rongalit) Tertiary butyl hydroperoxide 0.0047 〃 (NOF Products Perbutyl H69) The polymerization reaction was initiated at room temperature and continued until the polymerization conversion reached 90% or more. The resulting aqueous latex was coagulated with a 10% by weight aqueous solution of sodium sulfate, washed with water, and dried to obtain acrylic rubber (a).

[0106] Mooney viscosity PML of the obtained acrylic rubber (a) 1+4 (100℃) was 44. The mole fraction composition 1 Calculation from H-NMR (400 MHz, CD3C(=O)CD3, δ ppm using the following formula revealed that 9FMM was 0.28 mol % and EA+MBF was 99.72 mol %. α: Integrated value of the signal from 6.4 to 8.1 ppm β: Integrated value of the signal between 3.2 and 5.0 ppm 9FMM (mol%) = 200 × α / (9β-5α) EA + MBF (mol%) = 100 - 9FMM (mol%) In addition, the approximate weight fraction composition was calculated using the following formula, and it was found that 9FMM was 1.0 wt % and EA+MBF was 99.0 wt %. 9FMM(wt%)=(9FMM(mol%)×351.4×100) / [9FMM(mol%)×351.4+(EA+MBF(mol%))×100.8)] EA + MBF (wt%) = 100 - 9FMM (wt%) Furthermore, the acid value of the acrylic rubber (a) was measured to determine the MBF (wt%), which was 1.2 wt%.

[0107] Reference example 6 [Production of acrylic rubber (b)] In the production of acrylic rubber (a) in Reference Example 5, the charged monomer mixture Ethyl acrylate [EA] 97.2 % Mono-n-butyl fumarate [MBF] 1.6 〃 9FMM 1.2 〃 The acrylic rubber (b) was obtained using the above. The Mooney viscosity PML of the obtained acrylic rubber (b) 1+4 (100°C) was 46. The molar fraction composition and approximate weight fraction composition were determined in the same manner as in Reference Example 5, and were found to be 9FMM: 0.35 mol %, EA + MBF: 99.65 mol %, 9FMM: 1.2 wt %, and EA + MBF: 98.8 wt %. Furthermore, the MBF content (wt%) of the acrylic rubber (b) was determined by measuring the acid value, and was found to be 1.2 wt%.

[0108] Reference example 7 [Production of acrylic rubber (c)] In the production of acrylic rubber (a) in Reference Example 5, the charged monomer mixture Ethyl acrylate (EA) 57.2 〃 Ethyl acrylate [BA] 40.0 〃 Mono-n-butyl fumarate [MBF] 1.6 〃 9FMM 1.2 〃 The acrylic rubber (c) was obtained using the above. The Mooney viscosity PML of the obtained acrylic rubber (c) 1+4 (100°C) was 34. The molar fraction composition and approximate weight fraction composition were calculated using the following formula, and were found to be 9FMM: 0.38 mol%, EA + BA + MBF: 99.62 mol%, 9FMM: 1.2 wt%, and EA + BA + MBF: 98.8 wt%. α: Integrated value of the signal from 6.4 to 8.1 ppm β: Integrated value of the signal between 3.2 and 5.0 ppm 9FMM (mol%) = 200 × α / (9β-5α) EA+BA+MBF(mol%)=100-9FMM(mol%) 9FMM(wt%)=(9FMM(mol%)×351.4×100) / [9FMM(mol%)×351.4+(EA+BA+MBF(mol%))×110.3)] EA + BA + MBF (wt%) = 100 - 9FMM (wt%) Furthermore, the MBF content (wt%) of the acrylic rubber (c) was determined by measuring the acid value, and was found to be 1.2 wt%.

[0109] Example 1 Acrylic rubber (a) 100 parts by weight SRF carbon black (Tokai Carbon Products Seast GS) 60 Stearic acid (Miyoshi Oil Products TST) 1 〃 Polyoxyethylene stearyl ether phosphate 0.5% (Toho Chemical Industry Products Phosphanol RL-210) Hexamethylenediamine carbamate 0.2 〃 (Unimatec Cheminox AC6F) Crosslinking accelerator (Vulcofac ACT55, Safic-Alcan) 1 4,4'-Bis(α,α-dimethylbenzyl)diphenylamine (Ouchi Shinko Chemical Industry Products Nocrac CD) 2 Same Of the above components, acrylic rubber (a), SRF carbon black, stearic acid, and polyoxyethylene stearyl ether phosphate were mixed in a Banbury mixer. The resulting mixture and the remaining components were mixed using an open roll to obtain a crosslinkable acrylic rubber composition.

[0110] This was subjected to primary crosslinking at 180°C for 8 minutes using a 100-ton press molding machine, and then further oven crosslinking at 175°C for 4 hours, yielding a sheet-like crosslinked product (post-cure sheet) with a thickness of approximately 2 mm and a cylindrical crosslinked product with a diameter of approximately 29 mm and a height of approximately 12.5 mm.

[0111] The crosslinking characteristics of the acrylic rubber composition and the physical properties of the crosslinked product were measured as follows. Mooney scorch test: JIS K6300-1 compliant (125°C) Minimum Mooney viscosity measured using Mooney Viscometer AM-3 manufactured by Toyo Seiki Seisakusho Co., Ltd. (ML min) and scorch time (t5) values ​​were measured. Crosslinking test: JIS K6300-2 compliant (180°C, 12 minutes) Using a rotorless rheometer RLR-3 manufactured by Toyo Seiki Seisakusho, ML, MH, and tc (10) and tc(90) values ​​were measured. ML: Minimum torque MH: Maximum torque tc(10): Time required for the cross-linking torque to reach ML + (MH-ML) × 0.1 tc(90): Time required for the cross-linking torque to reach ML + (MH-ML) × 0.9 Normal physical properties: Measured on post-cure sheets in accordance with JIS K6251 and JIS K6253 Air heating aging test: Measured on post-cure sheets in accordance with JIS K6257 (190℃: 100 hours, 200 hours, 300 hours, 400 hours, 500 hours) Compression set test: JIS K6262 compliant (175℃: 70 hours, 500 hours)

[0112] Example 2 In Example 1, 2 parts by weight of CD-SO2-PIV was used in place of 4,4'-bis(α,α-dimethylbenzyl)diphenylamine.

[0113] Example 3 In Example 1, the following components were used as the acrylic rubber composition. Acrylic rubber (b) 100 parts by weight SRF Carbon Black (Seast GS) 60 Stearic acid (TST) 1 〃 Polyoxyethylene stearyl ether phosphate 0.5% (Phosphanol RL-210) 2,2-bis[4-(4-aminophenoxy)phenyl]propane 0.5 % (Tokyo Chemical Industry Products) Crosslinking accelerator (Vulcofac ACT55) 1 〃 CD-SO2-Bn 2 〃

[0114] Example 4 In Example 1, the following components were used as the acrylic rubber composition. Acrylic rubber (c) 100 parts by weight SRF Carbon Black (Seast GS) 60 Stearic acid (TST) 1 〃 Polyoxyethylene stearyl ether phosphate 0.5% (Phosphanol RL-210) Hexamethylenediamine carbamate (ChemiNox AC6F) 0.2 〃 Crosslinking accelerator (Vulcofac ACT55) 1 〃 CD-SO22 〃

[0115] Comparative Example 1 In Example 1, no hexamethylenediamine carbamate (ChemiNox AC6F) was used.

[0116] Comparative Example 2 In Example 2, no hexamethylenediamine carbamate (ChemiNox AC6F) was used.

[0117] Comparative Example 3 In Example 3, 2,2-bis[4-(4-aminophenoxy)phenyl]propane was not used.

[0118] Comparative Example 4 In Example 4, no hexamethylenediamine carbamate (ChemiNox AC6F) was used.

[0119] The results obtained in Examples 1 to 4 and Comparative Examples 1 to 4 are shown in the following table. table Example Comparative Example Measurement results 1 2 3 4 1 2 3 4 Mooney Coach Exam ML min (pts) 74 72 67 54 71 66 67 52 t5 (min) 1.6 1.4 2.0 1.8 1.5 1.5 2.5 3.0 Cross-linking test tc(10) (min) 0.45 0.46 0.62 0.50 0.53 0.55 0.57 0.62 tc(90) (min) 4.77 4.66 6.33 6.02 5.00 5.21 5.53 6.15 ML (N m) 0.22 0.23 0.21 0.17 0.21 0.21 0.20 0.16 MH (N m) 0.95 0.93 0.92 0.90 0.76 0.76 0.81 0.77 Normal state physical properties (post cure) Hardness (Duro A) 62 60 63 60 58 57 59 57 100% Modulus (MPa) 6.5 6.0 8.2 8.1 4.2 4.5 5.7 6.4 Breaking strength (MPa) 16.3 16.4 16.5 12.2 15.4 15.7 16.2 12.2 Elongation at break (%) 200 190 170 130 260 240 220 160 Heat aging test (190℃, 100 hours) Hardness Change (Duro A) +1 +2 +6 +4 +3 +4 +5 +5 100% Modulus Change (%) -43 -16 -16 -17 -38 -16 -16 -16 Breaking strength change rate (%) -23 -16 -10 -6 -37 -22 -17 -12 Change in elongation at break (%) +36 +17 +5 +15 +23 +13 +12 +6 Heat aging test (190℃, 200 hours) Hardness Change (Duro A) +3 +8 +7 +3 +7 +8 +6 +2 100% Modulus Change (%) -49 -28 -24 -26 -45 -33 -32 -31 Breaking strength change rate (%) -42 -32 -24 -19 -57 -42 -36 -27 Change in elongation at break (%) +38 +21 +4 +10 +33 +26 +18 +12 Heat aging test (190℃, 300 hours) Hardness Change (Duro A) +14 +13 +12 +6 +13 +11 +13 +7 100% Modulus Change (%) -46 -48 -44 -42 -36 -47 -47 -42 Breaking strength change rate (%) -57 -51 -44 -28 -68 -63 -59 -40 Change in elongation at break (%) +28 +32 +21 +29 +20 +43 +27 +18 Heat aging test (190℃, 400 hours) Hardness Change (Duro A) +21 +20 +19 +5 +27 +20 +21 +7 100% Modulus Change (%) -23 -43 -39 -47 +12 -40 -40 -48 Breaking strength change rate (%) -58 -61 -51 -38 -63 -70 -65 -50 Change in elongation at break (%) -13 +33 +12 +35 -32 +38 +17 +18 Heat aging test (190℃, 500 hours) Hardness Change (Duro A) +29 +21 +24 +10 +33 +27 +28 +13 100% Modulus Change (%) -32 -34 -40 -29 -25 -41 Breaking strength change rate (%) -55 -66 -59 -45 -56 -74 -67 -52 Change in elongation at break (%) -53 -2 +3 +9 -69 +8 +1 +7 Compression set test 175℃, 70 hours (%) 16 16 17 19 20 20 18 20 175℃, 500 hours (%) 34 30 35 29 41 37 39 33

[0120] Comparing the compression set test data between Examples 1 to 4 and Comparative Examples 1 to 4, respectively, shows that the compression set resistance of each Example is improved compared to the corresponding Comparative Example.

Claims

1. (A) 90 to 99.8% by weight of an alkyl(meth)acrylate and / or alkoxyalkyl(meth)acrylate monomer, 0.1 to 5% by weight of an α,β-unsaturated carboxylic acid monomer, and a copolymer of the general formula [I] (wherein R 1 is a hydrogen atom or a methyl group, and R 2 is a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms) Carbamate group-containing (meth)acrylate monomer copolymerized in a monomer ratio of 0.1 to 5% by weight, acrylic rubber containing carbamate groups and carboxyl groups. (B) Polyamine crosslinker and (C) Crosslinking accelerator A crosslinkable acrylic rubber composition comprising:

2. (A) 90 to 99.9% by weight of alkyl(meth)acrylate and / or alkoxyalkyl(meth)acrylate monomer and a copolymer of the general formula [I] (wherein R 1 is a hydrogen atom or a methyl group, and R 2 is a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms) and Acrylic rubber copolymerized with 90 to 99.9% by weight of alkyl (meth)acrylate and / or alkoxyalkyl (meth)acrylate monomer and 0.1 to 10% by weight of α,β-unsaturated carboxylic monomer The weight ratio of each component is 90 to 10% by weight and 10 to 90% by weight. (B) Polyamine crosslinker and (C) Crosslinking accelerator A crosslinkable acrylic rubber composition comprising:

3. A crosslinkable acrylic rubber composition according to claim 1 or 2, wherein the polyamine crosslinking agent is an aliphatic polyamine compound or an aromatic polyamine compound.

4. A crosslinkable acrylic rubber composition according to claim 3, wherein the aliphatic polyamine compound is hexamethylenediamine carbamate.

5. The crosslinkable acrylic rubber composition according to claim 3, wherein the aromatic polyamine compound is 2,2-bis[4-(4-aminophenoxy)phenyl]propane.

6. The crosslinkable acrylic rubber composition according to claim 1 or 2, wherein the crosslinking accelerator is 1,8-diazabicyclo[5.4.0]-7-undecene or an organic acid salt thereof.

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