WO2020153173A1 - Acrylic rubber composition and rubber crosslinked product - Google Patents

Abstract

Provided is an acrylic rubber composition containing: acrylic rubber; and a compound represented by general formula (1). (In general formula (1), R1 to R3 each independently represent a C1-C30 organic group which may have a substituent.)

Description

Acrylic rubber composition and crosslinked rubber

The present invention relates to an acrylic rubber composition, and relates to an acrylic rubber composition in which heat deterioration due to heat is effectively prevented and a rubber crosslinked product obtained by crosslinking the acrylic rubber composition.

With the development of petrochemistry, polymers composed of organic compounds have contributed to the development of humankind in various forms such as plastics, rubbers, fibers and films. Since these are used in various environments according to their applications, they have been improved so that they can be used for a long period of time by imparting durability under the assumed environment. For example, products have been developed in which plastics used outdoors have ultraviolet resistance and rubbers that function even in extremely cold regions have cold resistance.

On the other hand, the internal combustion engine represented by an engine, which has been used in large amounts with the development of industry, requires lubricating oil and generates a large amount of heat. Resistance is required. In particular, a polymer around an engine of an automobile is required to have properties such that it can maintain flexibility for a long time even when exposed to oil or high temperature and does not cause defects such as cracks. Various oil- and heat-resistant rubbers have been developed to meet these demands. Among them, acrylic rubber is a polymer that has rubber elasticity and is excellent in oil resistance, heat resistance, and flexibility, and is a seal around the engine of an automobile. It is widely used as a material such as gaskets, packings, and hoses, and its oil resistance and heat resistance are further enhanced by devising a cross-linking structure, an antioxidant and a compounding agent according to the required characteristics. For example, Patent Document 1 discloses an antiaging agent that improves heat resistance. However, such an anti-aging agent alone cannot suppress the decrease in the molecular weight of the polymer due to heat and the unintentional crosslinking reaction, and thus is insufficient to meet the further heat resistance requirement at 190° C. or higher.

Further, in Patent Document 2, by blending a specific amount of a specific triazine compound into a rubber component containing a regenerated butyl rubber, an environmental load is reduced, and a rubber composition having excellent scorch resistance, elastic modulus, and elongation at break is provided. Is disclosed. However, Patent Document 2 does not disclose not only the heat deterioration of the acrylic rubber but also the heat deterioration of the recycled butyl rubber.

Japanese Patent No. 5682575 JP, 2013-23675, A

The present invention has been made in view of the above circumstances, and an object thereof is to provide an acrylic rubber composition in which thermal deterioration due to heat is effectively prevented even in a high temperature environment (for example, an environment of 190° C. or higher).

The present inventors, as a result of intensive research to achieve the above object, found that the above problems can be solved by an acrylic rubber composition obtained by blending an acrylic rubber with a specific melamine compound, and complete the present invention. Came to.

That is, according to the present invention, there is provided an acrylic rubber composition containing an acrylic rubber and a compound represented by the following general formula (1).

(In the general formula (1), R ¹ to R ³ each independently represents an organic group having 1 to 30 carbon atoms which may have a substituent.)

In the present invention, R ¹ to R ³ in the compound represented by the general formula (1) are each independently an aromatic hydrocarbon ring group having 6 to 30 carbon atoms which may have a substituent, or It is preferably an aromatic heterocyclic group having 1 to 30 carbon atoms which may have a substituent.
In the present invention, R ¹ to R ³ in the compound represented by the general formula (1) are preferably a phenyl group which may have a substituent or a naphthyl group.
In the present invention, R ¹ to R ³ in the compound represented by the general formula (1) each independently have a linear, branched, or cyclic carbon number 1 which may have a substituent. It is preferably an alkyl group of ˜20.
In the present invention, the content of the compound represented by the general formula (1) is preferably 0.1 to 50 parts by weight with respect to 100 parts by weight of the acrylic rubber.
In the present invention, the content of the compound represented by the general formula (1) is more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the acrylic rubber.
In the present invention, the acrylic rubber is preferably a carboxyl group-containing acrylic rubber, an epoxy group-containing acrylic rubber, a halogen atom-containing acrylic rubber, or a carboxyl group- and halogen atom-containing acrylic rubber.
In the present invention, it is preferable that the acrylic rubber contains 0.1 to 100% by weight of ethylene-acrylate rubber.
In the present invention, an antioxidant other than the compound represented by the general formula (1) is further contained, and the compound represented by the general formula (1) and the antioxidant are contained with respect to 100 parts by weight of the acrylic rubber. The total content of is preferably 0.1 to 50 parts by weight.
In the present invention, it is preferable to further contain 0.05 to 20 parts by weight of a crosslinking agent with respect to 100 parts by weight of the acrylic rubber.

Further, according to the present invention, there is provided a rubber crosslinked product obtained by crosslinking the acrylic rubber composition of the present invention.
The crosslinked rubber product of the present invention is preferably an extruded product or a seal member.

According to the present invention, an acrylic rubber composition in which heat deterioration due to heat is effectively prevented even in a high temperature environment (for example, an environment of 190° C. or higher) and a rubber crosslinked product obtained by crosslinking the acrylic rubber composition. Can be provided.

The acrylic rubber composition of the present invention contains an acrylic rubber and a compound represented by the general formula (1) described later.

<Acrylic rubber>
The acrylic rubber used in the present invention has a (meth)acrylic acid ester monomer as a main component (in the present invention, 50% by weight or more based on all the monomer units in the acrylic rubber) in the molecule. [Meaning of acrylic acid ester monomer and/or methacrylic acid ester monomer. Hereinafter, the same applies to methyl (meth)acrylate and the like. The unit is not particularly limited as long as it contains a unit.

The (meth)acrylic acid ester monomer forming the (meth)acrylic acid ester monomer unit as the main component of the acrylic rubber used in the present invention is not particularly limited, but for example, (meth)acrylic acid alkyl ester Examples thereof include monomers and (meth)acrylic acid alkoxyalkyl ester monomers.

The (meth)acrylic acid alkyl ester monomer is not particularly limited, but an ester of an alkanol having 1 to 8 carbon atoms and (meth)acrylic acid is preferable, and specifically, methyl (meth)acrylate, ( Ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, (meth) 2-ethylhexyl acrylate, cyclohexyl (meth)acrylate and the like can be mentioned. Among these, ethyl (meth)acrylate and n-butyl (meth)acrylate are preferable, and ethyl acrylate is particularly preferable. These may be used alone or in combination of two or more.

The (meth)acrylic acid alkoxyalkyl ester monomer is not particularly limited, but an ester of an alkoxyalkyl alcohol having 2 to 8 carbon atoms and (meth)acrylic acid is preferable, and specifically, (meth)acrylic acid Methoxymethyl, ethoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-propoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate , 3-methoxypropyl (meth)acrylate, and 4-methoxybutyl (meth)acrylate. Among these, 2-ethoxyethyl (meth)acrylate and 2-methoxyethyl (meth)acrylate are preferable, and 2-ethoxyethyl acrylate and 2-methoxyethyl acrylate are particularly preferable. These may be used alone or in combination of two or more.

The content of the (meth)acrylic acid ester monomer unit in the acrylic rubber used in the present invention is 50 to 100% by weight, preferably 50 to 99.9% by weight, more preferably 60 to 99.5. %, more preferably 70 to 99.5% by weight, particularly preferably 70 to 99% by weight. By setting the content of the (meth)acrylic acid ester monomer unit in the above range, it is possible to improve the weather resistance, heat resistance, and oil resistance of the obtained rubber cross-linked product.

In the present invention, the (meth)acrylic acid ester monomer unit is 30 to 100% by weight of the (meth)acrylic acid alkyl ester monomer unit, and the (meth)acrylic acid alkoxyalkyl ester monomer unit 70 to It is preferably composed of 0% by weight.

The acrylic rubber used in the present invention may contain a crosslinkable monomer unit in addition to the (meth)acrylic acid ester monomer unit.

The crosslinkable monomer forming the crosslinkable monomer unit is not particularly limited, but examples thereof include α,β-ethylenically unsaturated carboxylic acid monomer; epoxy group-containing monomer; and halogen atom-containing monomer. Monomers; diene monomers; and the like. These crosslinkable monomers may be used alone or in combination of two or more.

The α,β-ethylenically unsaturated carboxylic acid monomer is not particularly limited, but, for example, α,β-ethylenically unsaturated monocarboxylic acid having 3 to 12 carbon atoms, α,β having 4 to 12 carbon atoms -Ethylenically unsaturated dicarboxylic acids, and monoesters of α,β-ethylenically unsaturated dicarboxylic acids having 4 to 12 carbon atoms and alkanols having 1 to 8 carbon atoms, and the like.

Specific examples of the α,β-ethylenically unsaturated monocarboxylic acid having 3 to 12 carbon atoms include acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, and cinnamic acid.
Specific examples of the α,β-ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms include butenedioic acid such as fumaric acid and maleic acid; itaconic acid; citraconic acid; chloromaleic acid.
Specific examples of monoesters of α,β-ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms and alkanol having 1 to 8 carbon atoms include monomethyl fumarate, monoethyl fumarate, mono-n-butyl fumarate and malein. Butenedioic acid mono-chain alkyl ester such as monomethyl acid acid, monoethyl maleate, mono-n-butyl maleate; monocyclopentyl fumarate, monocyclohexyl fumarate, monocyclohexenyl fumarate, monocyclopentyl maleate, monocyclohexyl maleate, malein Butenedioic acid monoesters having an alicyclic structure such as acid monocyclohexenyl; itaconic acid monoesters such as monomethyl itaconate, monoethyl itaconate, mono-n-butyl itaconate and monocyclohexyl itaconate; and the like.
Among these, butenedionic acid mono-chain alkyl ester or butenedionic acid monoester having an alicyclic structure is preferable, and mono-n-butyl fumarate, mono-n-butyl maleate, monocyclohexyl fumarate, and monocyclohexyl maleate are preferable. More preferably, monocyclohexyl maleate is even more preferable. These α,β-ethylenically unsaturated carboxylic acid monomers can be used alone or in combination of two or more. Incidentally, among the above-mentioned monomers, the dicarboxylic acid includes those existing as an anhydride.

In the present invention, when an α,β-ethylenically unsaturated carboxylic acid monomer is used as the crosslinkable monomer, the acrylic rubber can be a carboxyl group-containing acrylic rubber. When the acrylic rubber is a carboxyl group-containing acrylic rubber, the heat aging resistance of the acrylic rubber can be further improved.

When the acrylic rubber used in the present invention is a carboxyl group-containing acrylic rubber, the content of the α,β-ethylenically unsaturated carboxylic acid monomer unit is preferably 0.1 to 10% by weight, more preferably It is 0.5 to 7% by weight, more preferably 1 to 5% by weight. When the content of the α,β-ethylenically unsaturated carboxylic acid monomer unit is within the above range, the obtained rubber cross-linked product can have a better balance between strength and elongation. In particular, when the content of the α,β-ethylenically unsaturated carboxylic acid monomer unit is at least the above lower limit, crosslinking can be sufficiently performed, and the shape of the rubber cross-linked product obtained can be easily maintained. On the other hand, when the content of the α,β-ethylenically unsaturated carboxylic acid monomer unit is set to the above upper limit or less, the elongation of the obtained rubber cross-linked product is increased or the compression set is decreased. You can

When the acrylic rubber used in the present invention is a carboxyl group-containing acrylic rubber, the content of the carboxyl group, that is, the number of moles of the carboxyl group per 100 g of the acrylic rubber (ephr) is preferably 4×10 ^−4. ˜4×10 ⁻¹ (ephr), more preferably 1×10 ⁻³ to 2×10 ⁻¹ (ephr), further preferably 5×10 ⁻³ to 1×10 ⁻¹ (ephr). By setting the content of the carboxyl group to the above lower limit or more, crosslinking can be sufficiently performed, the mechanical properties of the obtained rubber cross-linked product can be improved, and the surface texture of the molded product can be smoothed. be able to. On the other hand, when the content of the carboxyl group is not more than the above upper limit, the elongation of the obtained rubber cross-linked product can be increased and the compression set can be decreased.

The epoxy group-containing monomer is not particularly limited, but examples thereof include epoxy group-containing (meth)acrylic acid ester and epoxy group-containing ether.

Specific examples of the epoxy group-containing (meth)acrylic acid ester include glycidyl (meth)acrylate.
Specific examples of the epoxy group-containing ether include allyl glycidyl ether and vinyl glycidyl ether. Among these, glycidyl methacrylate and allyl glycidyl ether are preferable. These monomers having an epoxy group can be used alone or in combination of two or more.

In the present invention, when a monomer having an epoxy group is used as the crosslinkable monomer, the acrylic rubber can be an epoxy group-containing acrylic rubber.

When the acrylic rubber used in the present invention is an epoxy group-containing acrylic rubber, the content of the epoxy group-containing monomer unit is preferably 0.1 to 10% by weight, more preferably 0.5 to 7% by weight. %, and more preferably 0.5 to 5% by weight. When the content of the monomer unit having an epoxy group is within the above range, the obtained rubber cross-linked product can have a better balance between strength and elongation. In particular, when the content of the monomer unit having an epoxy group is at least the above lower limit, crosslinking can be sufficiently performed, and the obtained rubber cross-linked product can be easily maintained in shape, while having an epoxy group. By setting the content of the monomer unit to the above upper limit or less, it is possible to increase the elongation of the obtained rubber cross-linked product or decrease the compression set.

The monomer having a halogen atom is not particularly limited, but examples thereof include unsaturated alcohol ester of halogen-containing saturated carboxylic acid, (meth)acrylic acid haloalkyl ester, (meth)acrylic acid haloacyloxyalkyl ester, (meth)acryl. Examples thereof include acid (haloacetylcarbamoyloxy) alkyl ester, halogen-containing unsaturated ether, halogen-containing unsaturated ketone, halomethyl group-containing aromatic vinyl compound, halogen-containing unsaturated amide, and haloacetyl group-containing unsaturated monomer.

Specific examples of unsaturated alcohol esters of halogen-containing saturated carboxylic acids include vinyl chloroacetate, vinyl 2-chloropropionate, and allyl chloroacetate.
Specific examples of haloalkyl (meth)acrylates include chloromethyl (meth)acrylate, 1-chloroethyl (meth)acrylate, 2-chloroethyl (meth)acrylate, and 1,2-dichloroethyl (meth)acrylate. , 2-chloropropyl (meth)acrylate, 3-chloropropyl (meth)acrylate, and 2,3-dichloropropyl (meth)acrylate.
Specific examples of the haloacyloxyalkyl (meth)acrylate include 2-(chloroacetoxy)ethyl (meth)acrylate, 2-(chloroacetoxy)propyl (meth)acrylate, and 3-(chloro)(meth)acrylate. Acetoxy)propyl, and 3-(hydroxychloroacetoxy)propyl (meth)acrylate.
Specific examples of (meth)acrylic acid (haloacetylcarbamoyloxy)alkyl ester include 2-(chloroacetylcarbamoyloxy)ethyl (meth)acrylate and 3-(chloroacetylcarbamoyloxy)propyl (meth)acrylate. Are listed.
Specific examples of the halogen-containing unsaturated ether include chloromethyl vinyl ether, 2-chloroethyl vinyl ether, 3-chloropropyl vinyl ether, 2-chloroethyl allyl ether, and 3-chloropropyl allyl ether.
Specific examples of the halogen-containing unsaturated ketone include 2-chloroethyl vinyl ketone, 3-chloropropyl vinyl ketone, and 2-chloroethyl allyl ketone.
Specific examples of the halomethyl group-containing aromatic vinyl compound include p-chloromethylstyrene, m-chloromethylstyrene, o-chloromethylstyrene, p-chloromethyl-α-methylstyrene and the like.
Specific examples of the halogen-containing unsaturated amide include N-chloromethyl(meth)acrylamide.
Specific examples of the haloacetyl group-containing unsaturated monomer include 3-(hydroxychloroacetoxy)propyl allyl ether and p-vinylbenzyl chloroacetic acid ester.

Among these, unsaturated alcohol ester of halogen-containing saturated carboxylic acid and halogen-containing unsaturated ether are preferable, vinyl chloroacetate and 2-chloroethyl vinyl ether are more preferable, and vinyl chloroacetate is further preferable. These monomers having a halogen atom can be used alone or in combination of two or more.

In the present invention, when a monomer having a halogen atom is used as the crosslinkable monomer, the acrylic rubber can be a halogen atom-containing acrylic rubber.

When the acrylic rubber used in the present invention is a halogen atom-containing acrylic rubber, the content of the monomer unit having a halogen atom is preferably 0.1 to 10% by weight, more preferably 0.5 to 7% by weight. %, and more preferably 0.5 to 5% by weight. When the content of the monomer unit having a halogen atom is within the above range, the obtained rubber cross-linked product can be more excellent in balance between strength and elongation. In particular, by setting the content of the monomer unit having a halogen atom to the above lower limit or more, crosslinking can be sufficiently performed, and the shape of the rubber cross-linked product obtained can be easily maintained, while having a halogen atom. By setting the content of the monomer unit to the above upper limit or less, it is possible to increase the elongation of the obtained rubber cross-linked product or decrease the compression set.

Further, in the present invention, by using an α,β-ethylenically unsaturated carboxylic acid monomer and a monomer having a halogen atom as the crosslinkable monomer, an acrylic rubber is prepared by using an acrylic rubber containing a carboxyl group and a halogen atom. It can be rubber.

When the acrylic rubber used in the present invention is a carboxyl group- and halogen atom-containing acrylic rubber, specific examples of the crosslinkable monomer include a crosslinkable monomer in the above-described carboxyl group-containing acrylic rubber and halogen atom-containing acrylic rubber. Examples thereof include those similar to the body, and of these, it is preferable to use methacrylic acid and p-chloromethylstyrene in combination.

When the acrylic rubber used in the present invention is a carboxyl group- and halogen atom-containing acrylic rubber, the total content of the α,β-ethylenically unsaturated carboxylic acid monomer unit and the halogen atom-containing monomer unit is It is preferably 0.1 to 10% by weight, more preferably 0.5 to 7% by weight, still more preferably 0.5 to 5% by weight. When the total content of the α,β-ethylenically unsaturated carboxylic acid monomer unit and the monomer unit having a halogen atom is at least the above lower limit, crosslinking can be sufficiently performed, and the resulting rubber crosslinked It is easy to maintain the shape of the product, and on the other hand, the rubber obtained by making the total content of the α,β-ethylenically unsaturated carboxylic acid monomer unit and the monomer unit having a halogen atom not more than the above upper limit. It is possible to increase the elongation of the crosslinked product and decrease the compression set.
The content ratio between the α,β-ethylenically unsaturated carboxylic acid monomer unit and the halogen atom-containing monomer unit is [α,β-ethylenically unsaturated carboxylic acid monomer unit: halogen atom-containing monomer unit]. The weight ratio of [mer unit] is preferably [1:1.5 to 1:10], more preferably [1:2 to 1:8].

Examples of the diene monomer include a conjugated diene monomer and a non-conjugated diene monomer.
Specific examples of the conjugated diene monomer include 1,3-butadiene, isoprene, and piperylene.
Specific examples of the non-conjugated diene monomer include ethylidene norbornene, dicyclopentadiene, dicyclopentadienyl (meth)acrylate, and 2-dicyclopentadienylethyl (meth)acrylate. ..

The above-mentioned α,β-ethylenically unsaturated carboxylic acid monomer, epoxy group-containing monomer, halogen atom-containing monomer, and diene monomer may be used alone or in combination of two or more. Can be used.

Incidentally, if the acrylic rubber used in the present invention is a carboxyl group-containing acrylic rubber, an epoxy group-containing acrylic rubber, a halogen atom-containing acrylic rubber, or a carboxyl group- and halogen atom-containing acrylic rubber described above, if necessary. , And may have other crosslinkable monomer units. The crosslinkable monomers forming the other crosslinkable monomer units may be used alone or in combination of two or more. The content of the other crosslinkable monomer unit in the acrylic rubber used in the present invention is preferably 0 to 9.9% by weight, more preferably 0 to 6.5% by weight, and further preferably 0 to 4. It is 5% by weight, particularly preferably 0 to 4% by weight. (However, the total amount of all crosslinkable monomer units in the acrylic rubber is preferably 0.1 to 10% by weight, more preferably 0.5 to 7% by weight, and further preferably 0.5 to 5% by weight, and particularly preferably 1 to 5% by weight.) By controlling the content of these other crosslinkable monomer units to be less than or equal to the above upper limit, the elongation of the obtained rubber crosslinked product may be increased or compression may be performed. The permanent set can be reduced.

In addition to the (meth)acrylic acid ester monomer unit and the crosslinkable monomer unit, the acrylic rubber used in the present invention may optionally contain a (meth)acrylic acid ester monomer or a crosslinkable monomer. It may have a unit of another monomer copolymerizable with the monomer.

Other copolymerizable monomers are not particularly limited, but include, for example, aromatic vinyl monomers, α,β-ethylenically unsaturated nitrile monomers, monomers having two or more acryloyloxy groups. (Hereinafter, it may be referred to as a “polyfunctional acrylic monomer”), an olefin-based monomer, a vinyl ether compound, and the like.

Specific examples of the aromatic vinyl monomer include styrene, α-methylstyrene, divinylbenzene and the like.
Specific examples of the α,β-ethylenically unsaturated nitrile monomer include acrylonitrile and methacrylonitrile.
Specific examples of the polyfunctional acrylic monomer include ethylene glycol di(meth)acrylate and propylene glycol di(meth)acrylate.
Specific examples of the olefin-based monomer include ethylene, propylene, 1-butene, 1-octene and the like.
Specific examples of vinyl ether compounds include vinyl acetate, ethyl vinyl ether, and n-butyl vinyl ether.

Among these, styrene, acrylonitrile, methacrylonitrile, ethylene and vinyl acetate are preferable, and acrylonitrile, methacrylonitrile, ethylene and vinyl acetate are more preferable.

The other copolymerizable monomers may be used alone or in combination of two or more.
The content of the other monomer unit in the acrylic rubber is preferably 0 to 50% by weight, more preferably 0 to 49.9% by weight, further preferably 0 to 39.5% by weight, and particularly preferably It is 0 to 29.5% by weight.

The acrylic rubber used in the present invention can be obtained by polymerizing the above monomers. As the form of the polymerization reaction, any of an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, and a solution polymerization method can be used, but from the viewpoint of easy control of the polymerization reaction, the emulsion polymerization method is used. Is preferred.

The emulsion polymerization may be batch type, semi-batch type, or continuous type. The polymerization is usually carried out in the temperature range of 0 to 70°C, preferably 5 to 50°C.

The weight average molecular weight (Mw) of the acrylic rubber used in the present invention is not particularly limited, but is preferably 50,000 to 5,000,000, more preferably 100,000 to 4,000,000, further preferably 150, It is 000 to 3,500,000. The weight average molecular weight of the acrylic rubber can be measured as a value in terms of polystyrene by gel permeation chromatography, for example.

The Mooney viscosity (ML1+4, 100° C.) (polymer Mooney) of the acrylic rubber used in the present invention produced in this manner is preferably 10 to 80, more preferably 20 to 70, and further preferably 25 to 60. ..

In the present invention, the acrylic rubber thus produced may be used alone or in combination of two or more.

In the present invention, as the acrylic rubber produced as described above, one containing 0.1 to 100% by weight of ethylene-acrylate rubber may be used.

When an acrylic rubber containing 0.1 to 100% by weight of ethylene-acrylate rubber is used, the ratio of ethylene-acrylate rubber to acrylic rubber other than ethylene-acrylate rubber is usually "ethylene-acrylate rubber: Acrylic rubber other than ethylene-acrylate rubber"=0.1 to 100% by weight: 99.9 to 0% by weight, preferably 10 to 100% by weight: 90 to 0% by weight, more preferably 20 to 100% by weight: 80 0 to 0% by weight. When the proportion of ethylene-acrylate rubber is within the above range, the processability of the acrylic rubber, the mechanical properties such as the strength of the obtained rubber cross-linked product, and the heat resistance can be made excellent.

Examples of the ethylene-acrylate rubber include 50 to 99.9% by weight of a (meth)acrylic acid ester monomer unit as a main component, 0.1 to 50% by weight of an ethylene monomer unit, and a crosslinkable monomer in a molecule. It is preferably a polymer containing 0 to 10% by weight of monomer units.

Further, as the acrylic rubber other than the ethylene-acrylate rubber, the above-mentioned (meth)acrylic acid ester monomer unit as a main component is contained in an amount of 50 to 100% by weight and the crosslinkable monomer unit is included in an amount of 0 to 10% by weight. A polymer or the like can be used.

The (meth)acrylic acid ester monomer forming the (meth)acrylic acid ester monomer unit that is suitable as the main component of the ethylene-acrylate rubber is not particularly limited, but the above-mentioned (meth)acrylic acid alkyl ester is used. Examples thereof include monomers and (meth)acrylic acid alkoxyalkyl ester monomers.

The content of the (meth)acrylic acid ester monomer unit in the ethylene-acrylate rubber is preferably 50 to 99.9% by weight, more preferably 59.5 to 99% by weight, further preferably 69 to 98% by weight. %. When the content of the (meth)acrylic acid ester monomer unit is at least the above lower limit, the weather resistance, heat resistance, and oil resistance of the obtained rubber cross-linked product can be improved.

In the ethylene-acrylate rubber, the (meth)acrylic acid ester monomer unit is 30 to 100% by weight of the (meth)acrylic acid alkyl ester monomer unit, and the (meth)acrylic acid alkoxyalkyl ester monomer unit. It is preferable that the unit is 70 to 0% by weight.

The ethylene-acrylate rubber used in the present invention contains an ethylene monomer unit as an essential component, and the content of the ethylene monomer unit is preferably 0.1 to 50% by weight, more preferably 0.5 to 40% by weight. , And more preferably 1 to 30% by weight. When the content of the ethylene monomer unit is within the above range, the obtained rubber cross-linked product is excellent in mechanical properties such as strength, weather resistance, heat resistance, and oil resistance.

The ethylene-acrylate rubber may contain a crosslinkable monomer unit in addition to the (meth)acrylic acid ester monomer unit and the ethylene monomer unit. As the crosslinkable monomer unit, those mentioned above can be mentioned. The content of the crosslinkable monomer unit in the ethylene-acrylate rubber is preferably 0 to 10% by weight, more preferably 0.5 to 7% by weight, still more preferably 1 to 5% by weight. By setting the content of the crosslinkable monomer unit to the above upper limit or less, the elongation of the obtained rubber crosslinked product can be increased or the compression set can be decreased.

Among the above-mentioned cross-linkable monomers, the ethylene-acrylate rubber used in the present invention can be a carboxyl group-containing ethylene-acrylate rubber having a carboxyl group as a cross-linking point, whereby it can be used in the present invention. From the viewpoint that the heat aging resistance of the acrylic rubber can be improved, α, β can be used as the cross-linking monomer that forms a part of the monomer units of the acrylic rubber other than the ethylene-acrylate rubber and the ethylene-acrylate rubber. -Preference is given to using ethylenically unsaturated carboxylic acid monomers.

In addition, the ethylene-acrylate rubber used in the present invention is a (meth)acrylic acid ester monomer unit, an ethylene monomer unit, and a crosslinkable monomer unit. It may have units of ester monomer, ethylene, and other monomer copolymerizable with the crosslinkable monomer. Examples of the other copolymerizable monomer include those described above. The content of the units of the other monomer in the ethylene-acrylic rubber used in the present invention is preferably 0 to 49.9% by weight, more preferably 0 to 39.5% by weight, and further preferably 0 to 29. % By weight.

The ethylene-acrylate rubber constituting the acrylic rubber used in the present invention can be obtained by polymerizing the above monomers. As the form of the polymerization reaction, as described above, any of the emulsion polymerization method, the suspension polymerization method, the bulk polymerization method, and the solution polymerization method can be used, and any polymerization method can be selected.

When the acrylic rubber used in the present invention contains an ethylene-acrylate rubber and an acrylic rubber other than the ethylene-acrylate rubber, the ethylene-acrylate rubber obtained by the above-mentioned method and the acrylic rubber other than the ethylene-acrylate rubber are used. The acrylic rubber used in the present invention can be obtained by mixing by a known method. The method of mixing is not particularly limited, but a method of performing dry blending after isolating each acrylic rubber is preferable.

<Compound represented by the general formula (1)>
The acrylic rubber composition of the present invention comprises the above-mentioned acrylic rubber and a compound represented by the following general formula (1).

(In the general formula (1), R ¹ to R ³ each independently represents an organic group having 1 to 30 carbon atoms which may have a substituent.)

In the general formula (1), R ¹ to R ³ are each independently an organic group having 1 to 30 carbon atoms which may have a substituent, and preferably have a substituent. A straight-chain, branched or cyclic alkyl group having 1 to 20 carbon atoms, an aromatic hydrocarbon ring group having 6 to 30 carbon atoms which may have a substituent, or a substituent It is also an aromatic heterocyclic group having 1 to 30 carbon atoms.

When the organic group is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms which may have a substituent, the substituent is a fluorine atom, a chlorine atom or a bromine atom. Halogen atoms such as; methoxy groups, ethoxy groups, isopropoxy groups and other alkoxy groups having 1 to 10 carbon atoms; nitro groups; cyano groups; and substituents such as phenyl groups, 4-methylphenyl groups, 2-chlorophenyl groups, etc. Optionally substituted phenyl group; halogenated alkyl group having 1 to 10 carbon atoms such as trifluoromethyl group and trichloromethyl group; 2 to 6 carbon atoms optionally having substituents such as vinyl group and allyl group An alkenyl group; an amino group which may have a substituent such as an amino group, a dimethylamino group, a phenylamino group; -OCF ₃ ; -C(=O)-R; -OC(=O)- R; -C(=O)-OR; -SO ₂ R; -SOR; -OC(=O)-OR; -NR-C(=O)-R'; -C(=O) —NRR′; —OC(═O)—NRR′; —NRC(═O)NR′R″; a substituent in which the O atom in the above exemplified substituents is replaced by an S atom; and the like. .. Here, R, R′, and R″ each independently represent a hydrogen atom or an organic group having 1 to 20 carbon atoms which may have a substituent. R, R′, and R″ are not particularly limited, but are a hydrogen atom, an alkyl group having 1 to 20 carbon atoms that may have a substituent, and a carbon atom having 2 carbon atoms that may have a substituent. An alkenyl group having 20 to 20 and a phenyl group having 6 to 20 carbon atoms which may have a substituent are preferable.

The organic group is an aromatic hydrocarbon ring group having 6 to 30 carbon atoms which may have a substituent, or an aromatic heterocyclic group having 1 to 30 carbon atoms which may have a substituent. In some cases, the substituent includes a halogen atom such as a fluorine atom, a chlorine atom and a bromine atom; an alkoxy group having 1 to 10 carbon atoms such as a methoxy group, an ethoxy group and an isopropoxy group; a nitro group; a cyano group; methyl. Groups, ethyl groups, t-butyl groups, and other alkyl groups having 1 to 10 carbon atoms; trifluoromethyl groups, trichloromethyl groups, and other halogenated alkyl groups having 1 to 10 carbon atoms, and substituents such as vinyl groups and allyl groups An alkenyl group having 2 to 6 carbon atoms which may have; an amino group which may have a substituent such as an amino group, a dimethylamino group and a phenylamino group; -OCF ₃ ; -C(=O) -R; -OC(=O)-R; -C(=O)-OR; -SO ₂ R; -SOR; -OC(=O)-OR; -NR-C(= O)-R';-C(=O)-NRR';-OC(=O)-NRR';-NRC(=O)NR'R''; Substituents substituted with S atoms; and the like. Here, R, R′, and R″ represent the same groups as those mentioned in the description of R, R′, and R″ above.

When the compound represented by the general formula (1) has a substituent as the organic group constituting R ¹ to R ³ , the carbon number of the organic group does not include the carbon number of the substituent. I shall. That is, the organic groups constituting R ¹ to R ³ may have the number of carbon atoms excluding the carbon atoms contained in the substituent in the range of 1 to 30. For example, when the organic group constituting R ¹ to R ³ is a methoxyethyl group, the organic group has 2 carbon atoms. That is, in this case, since the methoxy group is a substituent, the number of carbon atoms of the organic group is the number of carbon atoms of the methoxy group that is a substituent.

Among the above-mentioned organic groups having 1 to 30 carbon atoms which may have a substituent, have an aromatic hydrocarbon ring group having 6 to 30 carbon atoms which may have a substituent, or have a substituent. More preferably, it is an aromatic heterocyclic group having 1 to 30 carbon atoms, which may have a substituent, or an aromatic hydrocarbon ring group having 6 to 30 carbon atoms, or may have a substituent. Suitable examples of the aromatic heterocyclic group having 1 to 30 carbon atoms include the groups shown below. In the group shown below, a hydrogen atom bonded to a carbon atom or a nitrogen atom constituting an aromatic hydrocarbon ring or an aromatic heterocycle in the group shown below is a group substituted with the above-mentioned substituent. May be.

In particular, in the present invention, as the compound represented by the general formula (1), from the viewpoint that the effect of suppressing heat deterioration due to heat in a high temperature environment is high, the organic groups constituting R ¹ to R ³ are Each of them is preferably a phenyl group which may have a substituent or a naphthyl group, more preferably a phenyl group which may have a substituent, and among them, in the following general formula (2) The compounds represented are particularly suitable.

(In the general formula (2), R ⁴ to R ⁶ represent a hydrogen atom or an arbitrary substituent.)

The compound represented by the general formula (2) is the compound represented by the general formula (1), wherein R ¹ to R ³ are all phenyl groups which may have a substituent at the para position. Corresponding to the compound.
In the general formula (2), R ⁴ to R ⁶ represent a hydrogen atom or an arbitrary substituent, and examples of the substituent include a halogen atom such as a fluorine atom, a chlorine atom and a bromine atom; a methoxy group, an ethoxy group, an iso group. C1-C10 alkoxy groups such as propoxy groups; nitro groups; cyano groups; C1-C10 alkyl groups such as methyl groups, ethyl groups, t-butyl groups; trifluoromethyl groups, trichloromethyl groups, etc. Halogenated alkyl group having 1 to 10 carbon atoms; Alkenyl group having 2 to 6 carbon atoms which may have a substituent such as vinyl group and allyl group; Substituent such as amino group, dimethylamino group and phenylamino group -OCF ₃ ; -C(=O)-R; -OC(=O)-R; -C(=O)-OR; -SO ₂ R; -SOR; -OC(=O)-OR; -NR-C(=O)-R';-C(=O)-NRR';-OC(=O)-NRR';-NRC(=O)NR'R''; a substituent in which the O atom in the above-exemplified substituent is replaced with an S atom; and the like. Here, R, R′, and R″ represent the same groups as those mentioned in the description of R, R′, and R″ above.

Among the compounds represented by the general formula (2), those in which R ⁴ to R ⁶ are a hydrogen atom, an alkoxy group having 1 to 10 carbon atoms, or a halogenated alkyl group having 1 to 10 carbon atoms are preferable, A hydrogen atom, a methoxy group, or a trifluoromethyl group is particularly preferable.

The content of the compound represented by the general formula (1) in the acrylic rubber composition of the present invention is preferably 0.1 to 50 parts by weight, and more preferably 1 to 100 parts by weight of the acrylic rubber. It is up to 10 parts by weight. When the content of the compound represented by the general formula (1) is in the above range, it is possible to more appropriately prevent heat deterioration of the acrylic rubber composition when heated to a temperature of 190° C. or higher.

<Other ingredients>
Further, the acrylic rubber composition of the present invention further contains, in addition to the compound represented by the general formula (1), other antioxidants other than the compound represented by the general formula (1). Good. Other anti-aging agents include, but are not limited to, 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-4-ethylphenol, 2,6-di-t- Butyl-4-methylphenol, 2,6-di-t-butyl-4-sec-butylphenol, 2-(1-methylcyclohexyl)-4,6-dimethylphenol, 2,6-di-t-butyl-α- Monophenol anti-aging agents such as dimethylamino-p-cresol, 2,4-bis[(octylthio)methyl]-o-cresol, styrenated phenol, alkylated phenol; 2,2'-methylenebis(4-methyl-) 6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-methylenebis(2,6-di-t-butylphenol), 2,2'-methylenebis( 6-α-methylbenzyl-p-cresol), methylene-bridged polyhydric alkylphenol, 4,4′-butylidenebis(6-t-butyl-m-cresol), 4,4′-butylidenebis(3-methyl-6-) t-butylphenol), 2,2'-ethylidenebis(4,6-di-t-butylphenol), 1,1-bis-(4-hydroxyphenyl)cyclohexane, 2,2'-dihydroxy-3,3'- (Α-Methylcyclohexyl)-5,5′-dimethyldiphenylmethane, alkylated bisphenol, butylated reaction product of p-cresol and dicyclopentadiene, 2,5-di-t-butylhydroquinone, 2,5-di- Bis, tris, or polyphenolic antioxidants such as t-amylhydroquinone; 4,4'-thiobis(6-t-butyl-m-cresol), 4,4'-thiobis(6-t-butyl-o- Cresol), 4,4'-thiobis(3-methyl-6-t-butylphenol), bis(3,5-di-t-butyl-4-hydroxybenzyl) sulfide, etc. Phenolic anti-aging agent: phenyl-α-naphthylamine, octylated diphenylamine, 4,4′-bis(α,α-dimethylbenzyl)diphenylamine, p-(p-toluenesulfonylamide)diphenylamine, p-isopropoxy. Diphenylamine, bis(phenyl isopropylidene)-4,4-diphenylamine, N,N'-diphenylethylenediamine, N,N'-diphenylpropylenediamine, N,N'- Diphenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenyldiamine, 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, 4-(α-phenylethyl)diphenylamine, 4,4′-bis(α-phenylethyl)diphenylamine, 4,4′-bis(4-methylphenyl) ) Sulphonyl) aromatic secondary amine compounds such as diphenylamine; nickel dialkyldithiocarbamate such as nickel dimethyldithiocarbamate, nickel diethyldithiocarbamate, nickel dibutyldithiocarbamate; and the like.

Further, as the other antiaging agent, compounds represented by the following general formulas (3a) and (3b) can be used in addition to the above-mentioned compounds.

(In the general formula (3a), R ^a and R ^b each independently represent an organic group having 1 to 30 carbon atoms which may have a substituent. Z ^a and Z ^b are each independently. Represents a chemical single bond or —SO ₂ —, n and m are each independently 0 or 1, and at least one of n and m is 1. Further, in the general formula (3b), R ^c and R ^d each independently represent an organic group which may have a substituent and has 1 to 30 carbon atoms, and X ¹ and X ² each independently represent a hydrogen atom, a halogen atom or a substituent. An alkyl group having 1 to 10 carbon atoms which may have, a cyano group, a nitro group, —OR, —O—C(═O)—R, —C(═O)—OR, —O—C(= O)-OR, NRR'-, -NR-C(=O)-R', -C(=O)-NRR', or -OC(=O)-NRR', where R And R′ each independently represent a hydrogen atom or an organic group having 1 to 20 carbon atoms which may have a substituent, and a plurality of X ¹ and a plurality of X ² are all independently And different substituents are possible. n and m are each independently 0 or 1, and at least one of n and m is 1.)

In the general formula (3a), R ^a and R ^b each independently represent an organic group having 1 to 30 carbon atoms which may have a substituent.
The organic group having 1 to 30 carbon atoms which constitutes R ^a and R ^b is not particularly limited, and examples thereof include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec- Butyl, t-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl and other alkyl groups having 1 to 30 carbon atoms; cyclopropyl Group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, etc., cycloalkyl group having 3 to 30 carbon atoms; phenyl group, biphenyl group, naphthyl group, aryl group having 6 to 30 carbon atoms, such as anthranyl group; methoxy Group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, t-butoxy group, n-pentyloxy group, n-hexyloxy group and the like having 1 to 30 carbon atoms Alkoxy group;

Further, the above-mentioned organic groups constituting R ^a and R ^b may have a substituent, and the position of the substituent can be any position.
As such a substituent, when the organic group is an alkyl group, a halogen atom such as a fluorine atom, a chlorine atom or a bromine atom; an alkoxy having 1 to 10 carbon atoms such as a methoxy group, an ethoxy group or an isopropoxy group. Group; nitro group; cyano group; phenyl group which may have a substituent such as phenyl group, 4-methylphenyl group, 2-chlorophenyl group; and the like.
When the organic group is a cycloalkyl group or an aryl group, the substituent is a halogen atom such as a fluorine atom, a chlorine atom or a bromine atom; a methoxy group, an ethoxy group or an isopropoxy group having a carbon number of 1 to 10 alkoxy group; nitro group; cyano group; alkyl group having 1 to 10 carbon atoms such as methyl group, ethyl group, t-butyl group and the like.
Further, when the organic group is an alkoxy group, examples of the substituent include a halogen atom such as a fluorine atom, a chlorine atom and a bromine atom; a nitro group; a cyano group;
Moreover, in the said General formula (3a), when the organic group which comprises ^Ra and ^Rb has a substituent, the carbon number of an organic group shall not include the carbon number of this substituent.

R ^a and R ^b are each independently an alkyl group having 2 to 20 carbon atoms which may have a substituent, or an aryl group having 6 to 30 carbon atoms which may have a substituent. Preferably, a linear or branched alkyl group having 2 to 20 carbon atoms which may have a substituent, a phenyl group which may have a substituent, or a substituent which may have a substituent. More preferably, it is a naphthyl group, which may be a linear or branched alkyl group having 2 to 8 carbon atoms, which may have a substituent, or a phenyl group which may have a substituent. Is more preferable, and a linear or branched alkyl group having 2 to 8 carbon atoms which may have a substituent is particularly preferable. Examples of these substituents include those in which the organic group may have a substituent and has 1 to 30 carbon atoms, or an optionally substituted aryl group having 6 to 30 carbon atoms. The same thing as illustrated is mentioned.

Preferable specific examples of the organic group constituting such R ^a and R ^b include α-methylbenzyl group, α,α-dimethylbenzyl group, t-butyl group, phenyl group, 4-methylphenyl group and the like. Of these, an α,α-dimethylbenzyl group or a 4-methylphenyl group is more preferable, and an α,α-dimethylbenzyl group is more preferable. Note that these can be independent of each other.

Further, in the general formula (3a), Z ^a and Z ^b are each independently a chemical single bond or —SO ₂ —, and preferably a chemical single bond.

Furthermore, in the general formula (3a), n and m are each independently 0 or 1, and at least one of n and m is 1. It is preferable that both n and m are 1.

In the present invention, the compound represented by the general formula (3a) is preferably any of the compounds represented by the following general formulas (4) to (6).

(In the general formulas (4) to (6), R ^a , R ^b , Z ^a, and Z ^b are the same as those in the general formula (3a).)

Among the compounds represented by the above general formulas (4) to (6), the compounds represented by the general formulas (4) and (6) are preferable, and the compounds represented by the general formula (6) are more preferable.

In the general formulas (4) to (6), -Z ^a -R ^a and -Z ^b -R ^b are each independently an α-methylbenzyl group, an α,α-dimethylbenzyl group, t-butyl. Group, a phenylsulfonyl group, or a 4-methylphenylsulfonyl group, preferably an α,α-dimethylbenzyl group, or a 4-methylphenylsulfonyl group, more preferably an α,α-dimethylbenzyl group Is more preferable.

That is, in the present invention, in the general formula (3a), R ^a and R ^b are each independently a linear or branched alkyl group having 2 to 8 carbon atoms which may have a substituent. The group, and Z ^a and Z ^b are chemical single bonds, and n and m are preferably 1.

The compound represented by the general formula (3a) is obtained by applying a known method for producing a phenothiazine-based compound to obtain a phenothiazine-based compound as a precursor, and then oxidizing the obtained compound, It can be manufactured.

Specifically, the compound represented by the general formula (3a) is prepared by using the compound represented by the following general formula (7) (phenothiazine) as a starting material, and by the reaction method described in WO2011/093443A1. Introducing ^a substituent (-Z ^a -R ^a , -Z ^b -R ^b ) at 1-position, 3-position, 6-position and/or 8-position of the phenothiazine ring in (7), and S of the phenothiazine ring. Can be obtained by oxidation to give —SO ₂ —.

In the general formula (3b), R ^c and R ^d each independently represent an organic group having 1 to 30 carbon atoms which may have a substituent, and the number of carbon atoms which may have a substituent. 1 to 30 aromatic groups or cycloaliphatic groups are preferred.
The aromatic group having 1 to 30 carbon atoms is not particularly limited, and examples thereof include aromatic hydrocarbon groups such as phenyl group, biphenyl group, naphthyl group, phenanthryl group, anthranyl group, furyl group, pyrrolyl group and thienyl group. And aromatic heterocyclic groups such as pyridyl group and thiazolyl group.
The cyclic aliphatic group having 1 to 30 carbon atoms is not particularly limited, and examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group and the like. Among them, R ^c and R ^d are preferably each independently a phenyl group or a 4-methylphenyl group.
Further, the above-mentioned organic groups forming R ^c and R ^d may have a substituent, and the position of the substituent can be any position. Examples of such a substituent include a halogen atom such as a fluorine atom, a chlorine atom and a bromine atom; an alkoxy group having 1 to 10 carbon atoms such as a methoxy group, an ethoxy group and an isopropoxy group; a nitro group; a cyano group; a methyl group, And an alkyl group having 1 to 10 carbon atoms such as an ethyl group and a t-butyl group.
Moreover, in the said General formula (3b), when the organic group which comprises ^Rc and ^Rd has a substituent, the carbon number of an organic group shall not include the carbon number of this substituent.

In the general formula (3b), X ¹ and X ² are each independently a hydrogen atom, a halogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, sec- Number of carbon atoms 1 which may have a substituent such as butyl group, t-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group and n-decyl group To 10 alkyl groups, cyano groups, nitro groups, -OR, -OC(=O)-R, -C(=O)-OR, -OC(=O)-OR, NRR'-, It represents -NR-C(=O)-R', -C(=O)-NRR', or -OC(=O)-NRR'. Here, R and R′ each independently represent a hydrogen atom or an organic group having 1 to 20 carbon atoms which may have a substituent, and a plurality of X ¹ and a plurality of X ² are All independently, different substituents are possible. All of X ¹ and X ² are preferably hydrogen atoms.
As the substituent of the alkyl group having 1 to 10 carbon atoms which may have a substituent of X ¹ and X ² , the alkyl group having 1 to 30 carbon atoms which may have a substituent of R ^a and R ^b. The same groups as those exemplified as the substituent of the group can be mentioned.

In the present invention, as the compound represented by the general formula (3b), R ^c and R ^d are each independently an aromatic group having 1 to 30 carbon atoms and optionally having a substituent. Alternatively, it is preferable to select a compound that represents a cycloaliphatic group, X ¹ and X ² represent hydrogen atoms, and n and m represent 1, and are compounds represented by the following general formula (3c). Is more preferable.

(In the general formula (3c), R ^c and R ^d are the same as in the general formula (3b).)

The compound represented by the above general formula (3b) can be produced by applying a known production method. For example, it can be synthesized using the reaction method described in WO2011/058918A1.

Further, as other antiaging agents, in addition to the compounds described above and the compounds represented by the general formulas (3a) and (3b), the compound represented by the following general formula (8) may also be used. it can.

In the general formula (8), A ¹ and A ² each independently represent an arylene group having 6 to 18 carbon atoms which may have a substituent, and A ³ and A ⁴ are each independently And represents an organic group having a cyclic imide structure which may have a substituent.

In the general formula (8), A ¹ and A ² are each independently an arylene group having 6 to 18 carbon atoms which may have a substituent, and preferably have a substituent. A good arylene group having 6 to 10 carbon atoms, more preferably a phenylene group which may have a substituent, and still more preferably a 1,4-phenylene group, which has a particularly excellent antiaging effect. It is particularly preferable that both A ¹ and A ² are 1,4-phenylene groups from the viewpoint of achieving the desired performance. The substituents include halogen atoms such as fluorine atom, chlorine atom and bromine atom; alkoxy groups having 1 to 10 carbon atoms such as methoxy group, ethoxy group and isopropoxy group; nitro group; cyano group; methyl group and ethyl group. Group, an alkyl group having 1 to 10 carbon atoms such as t-butyl group; and the like.

Further, in the general formula (8), A ³ and A ⁴ are each independently an organic group having a cyclic imide structure which may have a substituent, and are represented by the following general formula (9) or (10). It is preferable that it is an organic group represented by these.

In the general formula (9), D represents a ring having 6 to 18 carbon atoms which may have a substituent, preferably a ring having 6 to 10 carbon atoms which may have a substituent. , D may be either monocyclic or polycyclic. In this case, the substituent may be an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 1 to 30 carbon atoms, —O—R ⁷ , —O—C(═O)—R ⁷ , or —C(═O ) -O-R ⁷ , -C(=O)-NR ⁷ (R ⁸ ), -NR ⁷ -C(=O)-R ⁸ , -CN, -SR ⁷ , -S-(=O)-R ⁷ or —S(═O) ₂ —R ^{7 and the} like. Note that R ⁷ and R ⁸ each independently represent an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 1 to 30 carbon atoms, or an aromatic group having 6 to 12 carbon atoms. In addition, m represents 0 or 1, and preferably 0.

In the general formula (10), R ⁹ and R ¹⁰ each independently have a hydrogen atom, an optionally substituted alkyl group having 1 to 30 carbon atoms, or an optionally substituted group. It represents an alkenyl group having 1 to 30 carbon atoms and is preferably a hydrogen atom or an alkyl group having 1 to 20 carbon atoms which may have a substituent, and may have a hydrogen atom or a substituent. More preferably, it is an alkyl group having a good carbon number of 1 to 10. In this case, as the substituent, a halogen atom such as a fluorine atom, a chlorine atom and a bromine atom; an alkoxy group having 1 to 10 carbon atoms such as a methoxy group, an ethoxy group and an isopropoxy group; a nitro group; a cyano group; a phenyl group , 4-methylphenyl group, 2-chlorophenyl group and the like; phenyl group which may have a substituent; and the like. In addition, n represents 0 or 1, and preferably 0.

Among the organic groups represented by the above general formula (9) or (10) constituting A ³ and A ⁴ , the following general formulas (11) to (16) are preferable because they have a more excellent antiaging effect. It is preferably any of the organic groups represented by.

In the general formulas (11) to (16), R ¹¹ to R ¹⁶ are each independently a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 1 to 30 carbon atoms, or —O—R ¹⁷ , -OC(=O)-R ¹⁷ , -C(=O)-OR ¹⁷ , -C(=O)-NR ¹⁷ (R ¹⁸ ), -NR ¹⁷ -C(=O)-R ¹⁸ , —CN, —SR ¹⁷ , —S—(═O)—R ¹⁷ or —S(═O) ₂ —R ¹⁷ , wherein R ¹⁷ and R ¹⁸ each independently have 1 carbon atom. It represents an alkyl group having ˜30, an alkenyl group having 1 to 30 carbon atoms, or an aromatic group having 6 to 12 carbon atoms. R ¹¹ to R ¹⁶ are preferably each independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and hydrogen. An atom or an alkyl group having 1 to 10 carbon atoms is particularly preferable. When there are a plurality of R ¹¹ to R ¹⁶ , they may be the same or different.

Among the organic groups represented by the general formulas (11) to (16), the general formulas (11), (12), (14) or (15) are preferable from the viewpoint that the antiaging action can be further enhanced. Is more preferable, the organic group represented by the general formula (11), (12), or (15) is more preferable, and the organic group represented by the general formula (15) is particularly preferable. ..

The compound represented by the general formula (8) is preferably any of compounds represented by the following general formulas (17) to (20).

In the general formulas (17) to (20), R ¹⁹ to R ³⁰ are each independently a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 1 to 30 carbon atoms, —OR ³¹ , or — OC(=O)-R ³¹ , -C(=O)-OR ³¹ , -C(=O)-NR ³¹ (R ³² ), -NR ³¹ -C(=O)-R ³² , -CN , —SR ³¹ , —S—(═O)—R ³¹ , or —S(═O) ₂ —R ³¹ , wherein R ³¹ and R ³² each independently represent an alkyl group having 1 to 30 carbon atoms. Represents a group, an alkenyl group having 1 to 30 carbon atoms, or an aromatic group having 6 to 12 carbon atoms. R ¹⁹ to R ³⁰ are preferably each independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and hydrogen. An atom or an alkyl group having 1 to 10 carbon atoms is particularly preferable. Further, A ¹ and A ² are the same as those in the general formula (8).

Among the compounds represented by the general formulas (17) to (20), the compound represented by the general formula (18) is particularly preferable from the viewpoint that the antiaging action can be further enhanced.

The compound represented by the above general formula (8) can be produced by applying a known production method. For example, it can be synthesized using the reaction method described in WO2018/159459A1.

Further, as other antiaging agents, in addition to the compounds described above, the compounds represented by the general formulas (3a), (3b), and (8), the compounds represented by the following general formula (21) Can also be used.

In the general formula (21), A ⁵ and A ⁶ each independently represent an aromatic group having 1 to 30 carbon atoms which may have a substituent. R ³³ , R ³⁵ , and R ³⁶ are each independently a hydrogen atom, a halogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, a cyano group, a nitro group, —OR ^1a , -OC(=O)-R ^1a , -C(=O)-OR ^1a , -OC(=O)-OR ^1a , -NR ^1b -C(=O)-R ^1a , -C( ═O)—NR ^1a R ^1c or —O—C(═O)—NR ^1a R ^1c . R ^1a and R ^1c each independently represent a hydrogen atom or an organic group having 1 to 30 carbon atoms which may have a substituent. R ^1b's each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. ^Examples of the organic group having 1 to 30 carbon atoms constituting R ^1a and R ^1c include —O—, —S—, —O—C(═O)—, —C(═O)—O—, —O— Selected from the group consisting of C(=O)-O-, -NR ^1d -C(=O)-, -C(=O)-NR ^1d -, -NR ^1d -, and -C(=O)-. At least one kind of linking group may intervene, except when two or more —O— or —S— are adjacently intervening. R ^1d's each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

In the general formula (21), R ³⁴ represents a hydrogen atom, a halogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, a cyano group, a nitro group, —O—C(═O). -R ^1e , -C(=O)-OR ^1e , -NR ^1b -C(=O)-R ^1e , -C(=O)-NR ^1e R ^1f , or -OC(=O)-NR ^1e represents R ^1f . R ^1e and R ^1f each independently represent an organic group which may have a substituent and has 1 to 30 carbon atoms. The organic groups having 1 to 30 carbon atoms constituting R ^1e and R ^1f are —O—, —S—, —O—C(═O)—, —C(═O)—O—, —O—C. At least selected from the group consisting of (=O)-O-, -NR ^1d -C(=O)-, -C(=O)-NR ^1d -, -NR ^1d -, and -C(=O)-. One type of linking group may intervene, but a case where two or more —O— or —S— are adjacently intervening is excluded. R ^1b and R ^1d each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

In a preferred embodiment of the compound represented by the general formula (21), A ⁵ is a phenylene group which may have a substituent having 1 to 30 carbon atoms, and A ⁶ is 1 to 1 carbon atoms. 30 is a phenyl group which may have a substituent, R ³³ , R ³⁵ , and R ³⁶ are hydrogen atoms, and R ³⁴ is —O—C(═O)—R ^1e , —C. (=O)-OR ^1e , -NR ^1b -C(=O)-R ^1e , -C(=O)-NR ^1e R ^1f , or -OC(=O)-NR ^1e R ^1f , R ^1b is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ^1e and R ^1f are each independently an organic group having 1 to 30 carbon atoms which may have a substituent. Can be selected.

Among the preferred embodiments described above of the compound represented by the general formula (21), a more preferred embodiment is that in the general formula (21), R ³⁴ is —C(═O)—OR ^1e , A diarylamine compound in which R ^1e is a phenyl group which may have a substituent having 1 to 18 carbon atoms or a naphthyl group which may have a substituent having 1 to 18 carbon atoms can be selected. ..

Among the above-described more preferable embodiments of the compound represented by the general formula (21), as a more preferable embodiment, in the general formula (21), R ³⁴ is —C(═O)—OR ^1e . , R ^1e is an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aromatic group having 4 to 30 carbon atoms which may have a substituent, and constitutes R ^1e . As the substituent, each independently, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an aralkyl group having 1 to 20 carbon atoms, an aromatic group having 6 to 30 carbon atoms, a cyano group, a nitro group, a sulfo group, -OR ^e , -OC(=O)-R ^e , -C(=O)-OR ^e , -OC(=O)-OR ^e , -NR ^g -C(=O)-R ^e , -C(=O)-NR ^e R ^f , -OC(=O)-NR ^e R ^f , -SR ^e , -S(=O)-R ^e , or -S(=O) ₂ -. R ^e , R ^e , R ^f , and R ^g are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group, and A ⁵ and A ⁶ are each independently. A substituent having 6 to 30 carbon atoms, which may have a substituent, and examples of the substituent constituting A ⁵ and A ⁶ include an alkyl group having 1 to 10 carbon atoms and a substituent having 1 to 10 carbon atoms. Selecting a diarylamine compound having a halogen-substituted alkyl group, a halogen atom, a cyano group, or a nitro group, that is, a phthalimide group-containing diarylamine compound represented by the following general formula (22) and having an ester group at the 4-position: You can

In the general formula (22), R ³⁷ to R ⁴⁵ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a halogen-substituted alkyl group having 1 to 10 carbon atoms, a halogen atom, a cyano group, or It is a nitro group.

Further, the diarylamine compound represented by the general formula (21) will be specifically described.

In the general formula (21), R ³⁴ is preferably an ester group represented by —C(═O)—OR ^1e because the compound can be easily produced. Here, R ^1e is an organic group having 1 to 30 carbon atoms which may have a substituent, and ^examples of the organic group having 1 to 30 carbon atoms which constitutes R ^1e include an alkyl group, a cycloalkyl group, Many aliphatic groups and aromatic groups such as aryl groups, arylalkyl groups, alkylaryl groups, arylalkylaryl groups, and alkoxy groups can be selected, but from the viewpoint of heat resistance, aromatic groups, particularly phenyl groups or naphthyl groups. Is preferably selected.

Further, in the general formula (21), R ³⁴ is —C(═O)—OR ^1e , and R ^1e is an aromatic group which may have a substituent and has 1 to 20 carbon atoms. When it is used as an antioxidant, the effect of further improving the heat resistance can be obtained, which is particularly preferable. R ³⁴ is —C(═O)—OR ^1e , and R ^1e has a phenyl group which may have a substituent having 1 to 18 carbon atoms or a substituent which has 1 to 18 carbon atoms. It is most preferable that the ester structure is a naphthyl group which may be added, because the effect of further improving heat resistance can be obtained.

The compound represented by the above general formula (21) can be produced by applying a known production method. For example, it can be synthesized using the reaction method described in Japanese Patent No. 5732673.

When using other antioxidants, the total content of the compound represented by the general formula (1) and other antioxidants in the acrylic rubber composition of the present invention is 100 parts by weight of acrylic rubber. On the other hand, it is preferably 0.1 to 50 parts by weight, more preferably 1 to 10 parts by weight.

The content of the other antioxidant in the acrylic rubber composition of the present invention is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 10 parts by weight with respect to 100 parts by weight of the acrylic rubber. 5 parts by weight, more preferably 0.5 to 2.5 parts by weight.

The acrylic rubber composition of the present invention may further contain a crosslinking agent. By adding a cross-linking agent to the acrylic rubber composition of the present invention, a cross-linkable one (cross-linkable acrylic rubber composition) can be obtained, and a rubber cross-linked product is obtained by a crosslinking reaction by heating or the like. You can

The cross-linking agent is not particularly limited, and examples thereof include polyvalent amine compounds such as diamine compounds, and carbonates thereof; sulfur; sulfur donors; triazine thiol compounds; organic carboxylic acid ammonium salts; dithiocarbamic acid metal salts; Conventionally known cross-linking agents such as acids; quaternary onium salts; imidazole compounds; isocyanuric acid compounds; organic peroxides can be used. It may be appropriately selected depending on the type of the monomer unit. These cross-linking agents can be used alone or in combination of two or more.

The polyvalent amine compound and its carbonate salt are not particularly limited, but a polyvalent amine compound having 4 to 30 carbon atoms and its carbonate salt are preferable. Examples of such polyvalent amine compounds and their carbonates include aliphatic polyamine compounds, their carbonates, and aromatic polyamine compounds. On the other hand, guanidine compounds such as those having a non-conjugated nitrogen-carbon double bond are not included.

The aliphatic polyvalent amine compound and the carbonate thereof are not particularly limited, and examples thereof include hexamethylenediamine, hexamethylenediamine carbamate, and N,N′-dicinnamylidene-1,6-hexanediamine. Among these, hexamethylene diamine carbamate is preferable.

The aromatic polyvalent amine compound is not particularly limited, and examples thereof include 4,4′-methylenedianiline, p-phenylenediamine, 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-aminophenoxy)phenyl]propane, Examples include 4,4'-diaminobenzanilide, 4,4'-bis(4-aminophenoxy)biphenyl, m-xylylenediamine, p-xylylenediamine, and 1,3,5-benzenetriamine. Among these, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane is preferable.

Examples of the sulfur donor include dipentamethylene thiuram hexasulfide, triethyl thiuram disulfide and the like.
Examples of the triazine thiol compound include 1,3,5-triazine-2,4,6-trithiol, 6-anilino-1,3,5-triazine-2,4-dithiol, 6-dibutylamino-1,3 ,5-triazine-2,4-dithiol, 6-diallylamino-1,3,5-triazine-2,4-dithiol, and 6-octylamino-1,3,5-triazine-2,4-dithiol Among these, 1,3,5-triazine-2,4,6-trithiol is preferable among them.

Examples of the carboxylic acid ammonium salt include ammonium benzoate and ammonium adipate.
Examples of the metal salt of dithiocarbamate include zinc dimethyldithiocarbamate.
Examples of the polycarboxylic acid include tetradecanedioic acid and the like.
Examples of the quaternary onium salt include cetyl trimethyl ammonium bromide.
Examples of the imidazole compound include 2-methylimidazole and the like.
Examples of the isocyanuric acid compound include ammonium isocyanuric acid.

When the crosslinking agent is blended in the acrylic rubber composition of the present invention, the blending amount is preferably 0.05 to 20 parts by weight, more preferably 0.1 to 100 parts by weight of the acrylic rubber. To 15 parts by weight, more preferably 0.3 to 12 parts by weight. When the content of the cross-linking agent is within the above range, the cross-linking is sufficiently performed, and when the cross-linked rubber is obtained, the obtained cross-linked rubber can have excellent mechanical properties.

In addition to the above components, the acrylic rubber composition of the present invention may be compounded with compounding agents usually used in the rubber processing field. Examples of such compounding agents include reinforcing fillers such as carbon black and silica; non-reinforcing fillers such as calcium carbonate and clay; crosslinking accelerators; light stabilizers; plasticizers; processing aids; lubricants; Adhesives, lubricants, flame retardants, antifungal agents, antistatic agents, colorants, silane coupling agents, crosslinking retardants, and the like. The compounding amount of these compounding agents is not particularly limited as long as the objects and effects of the present invention are not impaired, and the compounding amount can be appropriately mixed according to the compounding purpose.

<Method for preparing acrylic rubber composition>
The method for preparing the acrylic rubber composition of the present invention is not particularly limited, but a method of mixing the acrylic rubber and the compound represented by the general formula (1) together with various compounding agents added as necessary is available. It is suitable.

The mixing method is not particularly limited, and examples thereof include a method of kneading using a kneader such as a roll, intermix, kneader, Banbury mixer, and screw mixer. Moreover, you may perform mixing in a solvent.

When a cross-linking agent is added, each component except the cross-linking agent and the heat-unstable cross-linking auxiliary agent is kneaded with a mixer such as a Banbury mixer, a Brabender mixer, an intermixer, and a kneader, and then rolled. It can be prepared by carrying out a secondary kneading by adding a crosslinking agent, a heat-labile crosslinking auxiliary agent, etc.

The acrylic rubber composition of the present invention can be obtained as described above. The acrylic rubber composition of the present invention contains an acrylic rubber and a compound represented by the above general formula (1). According to the acrylic rubber composition of the present invention, by blending the compound represented by the general formula (1), it is possible to effectively suppress the heat deterioration when heated at a temperature of 190° C. or higher. ..

When a cross-linking agent is added to the acrylic rubber composition of the present invention, a rubber cross-linked product can be obtained by cross-linking this.
The crosslinked rubber is produced by molding an acrylic rubber composition containing a crosslinking agent and crosslinking the composition. The method for molding and crosslinking the acrylic rubber composition is not particularly limited, but for example, using a uniaxial or multiaxial extruder, the crosslinkable rubber composition is extruded into a molded body, and then heated and crosslinked. Method: a method of molding with a mold using an injection molding machine, an extrusion blow molding machine, a transfer molding machine, a press molding machine or the like, and crosslinking by heating at the same time as molding, and the like. Among these methods, a method using an extruder or an injection molding machine is preferable, and a method using an extruder is particularly preferable. Whether to perform molding and crosslinking at the same time or to perform crosslinking after molding is not particularly limited and may be selected according to the molding method, the vulcanization method, the size of the molded body, and the like.

When molding and crosslinking the acrylic rubber composition, the molding temperature is preferably 15 to 220°C, more preferably 20 to 200°C. The crosslinking temperature is preferably 100° C. or higher, more preferably 120° C. to 250° C. The crosslinking time may be arbitrarily selected within the range of 1 minute to 5 hours. As a heating method, a method usually used for crosslinking rubber such as electric heating, steam heating, oven heating, UHF (ultra high frequency) heating and hot air heating may be appropriately selected.

Also, depending on the shape and size of the rubber cross-linked material, even if the surface is cross-linked, it may not be fully cross-linked to the inside, so secondary heating may be performed to carry out secondary cross-linking. In carrying out the secondary crosslinking, the heating temperature is preferably 100 to 220° C., more preferably 130 to 210° C., and the heating time is preferably 30 minutes to 10 hours, more preferably 1 to 5 hours. ..

The rubber cross-linked product thus obtained is obtained by using the above-mentioned acrylic rubber composition of the present invention. It is possible to effectively suppress the heat deterioration due to the heat when heated above. Therefore, the rubber cross-linked product obtained in this manner makes use of its characteristics, and O-rings, packings, diaphragms, oil seals, shaft seals, bearing seals, mechanical seals, well head seals, seals for electric/electronic devices, Various types of seals such as seals for pneumatic equipment; cylinder head gaskets installed at the connection between the cylinder block and cylinder head, rocker cover gaskets installed at the connection between the rocker cover and cylinder head, oil pan and cylinder block or transmission Various types of gaskets such as an oil pan gasket installed at the connecting part with the case, a gasket for a fuel cell separator installed between a pair of housings that sandwich a unit cell equipped with a positive electrode, an electrolyte plate and a negative electrode, and a top cover gasket for hard disk drives. Gaskets; various belts; fuel hoses, turbo air hoses, oil hoses, radiator hoses, heater hoses, water hoses, vacuum brake hoses, control hoses, air conditioner hoses, brake hoses, power steering hoses, air hoses, marine hoses, risers, flows Various hoses such as lines; various boots such as CVJ boots, propeller shaft boots, constant velocity joint boots, rack and pinion boots, etc.; cushioning materials, dynamic dampers, rubber couplings, air springs, vibration damping materials, and other damping material rubber parts; It is preferably used as such.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In addition, "part" in each example is based on weight unless otherwise specified.
Various physical properties were evaluated according to the following methods.

[Weight residual rate]
The film of the acrylic rubber composition was heated in air at 190° C. for 336 hours to obtain a film of the acrylic rubber composition after heating. The film weight of the acrylic rubber composition before and after heating was measured, and the residual weight ratio of the film of the acrylic rubber composition was calculated according to the following formula. It is considered that the higher the weight residual rate is, the lower the molecular weight and volatilization due to the heating and decomposition of the acrylic rubber in the acrylic rubber composition are suppressed, so that it can be judged that the heat deterioration due to heat is suppressed. ..
Weight residual rate (%)=(film weight after heating)/(film weight before heating)×100

[Dissolution rate and swelling degree]
The film of the heated acrylic rubber composition used in the measurement of the weight residual ratio was immersed in toluene at room temperature for 24 hours to swell the film. The swollen film and toluene were separated, and the weight of the swollen film was measured.
Next, the swollen film was dried in a vacuum dryer at 35° C. for 15 hours, and the film weight after vacuum drying was measured. The dissolution rate of the film of the acrylic rubber composition was calculated according to the following formula. When the cross-linking reaction proceeds by heating, it is considered that the three-dimensionalization progresses due to the progress of the cross-linking reaction and becomes an insoluble component. Therefore, the dissolution rate is basically in the range of about 3 to 20%. It is desirable that the dissolution rate be within such a range, and it can be judged that deterioration due to heat due to heat, specifically, increase in hardness due to progress of crosslinking reaction due to heating was suppressed. On the other hand, even when the dissolution rate is in the range of 3 to 20%, the decomposition reaction progresses at the same time as the crosslinking reaction, and as a result, the decrease in the dissolution rate may be suppressed. When the residual rate and the swelling rate are low, it is considered that the increase in hardness due to the progress of the cross-linking reaction due to heating is suppressed, and the reduction in molecular weight due to heating and decomposition is promoted.
Dissolution rate (%)={(weight of film after heating)-(weight of film dried after swelling in vacuum)}/(weight of film after heating)×100
Further, the degree of swelling of the film of the acrylic rubber composition was calculated according to the following formula. When the cross-linking reaction proceeds by heating, the cross-linking reaction progresses, the cross-linking point increases, and generally, as the cross-linking point increases, the degree of swelling with the organic solvent decreases, so that the higher the swelling degree, It can be judged that the heat deterioration due to heat, specifically, the increase in hardness due to the progress of the crosslinking reaction due to heating was suppressed.
Swelling degree (%)=(Swelling film weight)/(Swelling and vacuum dried film weight)×100

[Example 1]
48.5 g of a carboxyl group-containing acrylic rubber (product name “Hytemp AR212HR”, manufactured by Nippon Zeon Co., Ltd.) and triphenylmelamine (a compound in which R ⁴ , R ⁵ , and R ⁶ =H in the above general formula (2)) 118.5 mg ( A solution was prepared by dissolving 36 parts of THF with 3.0 parts of 0.33 mmol of 100 parts of the carboxyl group-containing acrylic rubber. The solution was poured into a fluororesin petri dish having a diameter of 10 cm, air-dried for 15 hours, and then vacuum-dried for 4 hours in a vacuum dryer at 30° C. to obtain an acrylic rubber composition film. The obtained film was cut into a size of 1.5 cm square, and the weight residual rate, dissolution rate and swelling degree after heating at 190° C. for 336 hours were calculated according to the above method. The results are shown in Table 1.

[Example 2]
Instead of 118.5 mg of triphenylmelamine, 148 mg of tris(4-methoxyphenyl)melamine (a compound in which R ⁴ , R ⁵ , and R ⁶ =OCH ₃ in the general formula (2) above) (carboxyl group-containing acrylic rubber 100) A film of an acrylic rubber composition was obtained in the same manner as in Example 1 except that 3.7 parts (0.33 mmol, 0.33 mmol) was used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]
Acrylic was prepared in the same manner as in Example 2 except that the amount of tris(4-methoxyphenyl)melamine used was changed from 148 mg to 296 mg (7.4 parts, 0.66 mmol per 100 parts of the carboxyl group-containing acrylic rubber). A film of the rubber composition was obtained. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

[Example 4]
Instead of 118.5 mg of triphenylmelamine, 188 mg of tris[4-(trifluoromethyl)phenyl]melamine (a compound in which R ⁴ , R ⁵ , and R ⁶ =CF ₃ in the above general formula (2) are carboxyl groups) A film of an acrylic rubber composition was obtained in the same manner as in Example 1 except that 4.7 parts, 0.33 mmol, based on 100 parts of the contained acrylic rubber was used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
A film of an acrylic rubber composition was obtained in the same manner as in Example 1 except that triphenylmelamine was not used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

[Comparative example 2]
Instead of 118.5 mg of triphenylmelamine, octylated diphenylamine (product name "Nocrac AD-F", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) 132 mg (3.3 parts, 0.33 mmol per 100 parts of carboxyl group-containing acrylic rubber) A film of an acrylic rubber composition was obtained in the same manner as in Example 1 except that (1) was used. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
Instead of 118.5 mg of triphenylmelamine, 4,4′-bis(α,α-dimethylbenzyl)diphenylamine (product name “Nocrac CD”, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) 136 mg (100 parts of carboxyl group-containing acrylic rubber) In the same manner as in Example 1, except that 3.4 parts, 0.33 mmol) was used, a film of an acrylic rubber composition was obtained. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

As shown in Table 1, the acrylic rubber compositions of Examples 1 to 4 containing the acrylic rubber and the compound represented by the general formula (1) had a weight residual ratio, a solubility, and a weight residual ratio after heating at 190° C. for 336 hours. In addition, the degree of swelling was high, and heat deterioration due to heat was appropriately suppressed. Further, from this result, it can be said that the rubber cross-linked product obtained by using the acrylic rubber composition of the present invention can appropriately suppress the heat deterioration due to heat.

On the other hand, in Comparative Example 1 in which the antioxidant was not mixed, the weight residual rate, the dissolution rate, and the swelling degree after heating at 190° C. for 336 hours were low, and the heat deterioration due to heat was remarkable.
Further, Comparative Examples 2 and 3 in which an antioxidant other than the compound represented by the general formula (1) was blended had a low weight residual ratio and swelling degree after heating at 190° C. for 336 hours, and had an effect of suppressing heat deterioration due to heat. Was insufficient. In Comparative Examples 2 and 3, the dissolution rate is relatively high, but the weight residual rate after heating at 190°C for 336 hours is low, and the swelling degree is low. It is considered that the reason is that the decomposition by heating is promoted and the molecular weight of the acrylic rubber is lowered, rather than the suppression of the crosslinking reaction by heating.

Claims (16)

1. An acrylic rubber composition containing acrylic rubber and a compound represented by the following general formula (1).
   

   

   (In the general formula (1), R ¹ to R ³ each independently represents an organic group having 1 to 30 carbon atoms which may have a substituent.)
2. R ¹ to R ³ in the compound represented by the general formula (1) each independently have an optionally substituted aromatic hydrocarbon ring group having 6 to 30 carbon atoms or a substituent. The acrylic rubber composition according to claim 1, which is an aromatic heterocyclic group having 1 to 30 carbon atoms which may be added.
3. The acrylic rubber composition according to claim 2, wherein R ¹ to R ³ in the compound represented by the general formula (1) are a phenyl group which may have a substituent or a naphthyl group.
4. R ¹ to R ³ in the compound represented by the general formula (1) are each independently linear, branched or cyclic C 1-20 alkyl which may have a substituent. The acrylic rubber composition according to claim 1, which is a base.
5. The acrylic rubber composition according to any one of claims 1 to 4, wherein the content of the compound represented by the general formula (1) is 0.1 to 50 parts by weight relative to 100 parts by weight of the acrylic rubber.
6. The acrylic rubber composition according to claim 5, wherein the content of the compound represented by the general formula (1) is 1 to 10 parts by weight based on 100 parts by weight of the acrylic rubber.
7. The acrylic rubber composition according to any one of claims 1 to 6, wherein the acrylic rubber is a carboxyl group-containing acrylic rubber.
8. The acrylic rubber composition according to any one of claims 1 to 6, wherein the acrylic rubber is an epoxy group-containing acrylic rubber.
9. The acrylic rubber composition according to any one of claims 1 to 6, wherein the acrylic rubber is a halogen atom-containing acrylic rubber.
10. The acrylic rubber composition according to any one of claims 1 to 6, wherein the acrylic rubber is a carboxyl group- and halogen atom-containing acrylic rubber.
11. The acrylic rubber composition according to any one of claims 1 to 10, wherein the acrylic rubber contains 0.1 to 100% by weight of ethylene-acrylate rubber.
12. The composition further contains an antioxidant other than the compound represented by the general formula (1), and contains the total amount of the compound represented by the general formula (1) and the antioxidant with respect to 100 parts by weight of the acrylic rubber. The acrylic rubber composition according to any one of claims 1 to 11, wherein the amount is 0.1 to 50 parts by weight.
13. The acrylic rubber composition according to any one of claims 1 to 12, which further contains 0.05 to 20 parts by weight of a crosslinking agent with respect to 100 parts by weight of the acrylic rubber.
14. A rubber cross-linked product obtained by cross-linking the acrylic rubber composition according to claim 13.
15. The crosslinked rubber product according to claim 14, which is an extruded product.
16. The rubber cross-linked product according to claim 14, which is a seal member.