JP6696585B2 - Acrylic rubber and crosslinked rubber - Google Patents

Description

  TECHNICAL FIELD The present invention relates to an acrylic rubber and a rubber crosslinked product, and more specifically, an acrylic rubber that provides a rubber crosslinked product having high tensile strength, excellent compression set resistance and water resistance, and a rubber crosslinked product using this acrylic rubber. Regarding

  Acrylic rubber is a polymer containing acrylic acid ester as a main component and is generally known as a rubber having excellent heat resistance, oil resistance and ozone resistance, and is widely used in fields related to automobiles.

  Such an acrylic rubber is usually obtained by emulsion-polymerizing a monomer mixture constituting the acrylic rubber, adding a coagulant to the obtained emulsion-polymerized solution to coagulate, and drying the hydrous crumb obtained by coagulation. It is manufactured by doing (see, for example, Patent Document 1).

  On the other hand, in recent years, in addition to heat resistance and oil resistance, in addition to heat resistance and oil resistance, compression set resistance and compression set resistance of automobile parts such as sealing materials, hose materials, vibration damping materials, tube materials, belt materials, and boot materials have been improved. It is required to have excellent water resistance. However, the conventional acrylic rubber such as the acrylic rubber described in Patent Document 1 does not always have sufficient water resistance, and therefore cannot meet the recent demand for water resistance.

JP-A-7-145291

  The present invention has been made in view of such an actual situation, and has high tensile strength, compression set resistance, and acrylic rubber that gives a crosslinked rubber excellent in water resistance, and rubber using this acrylic rubber. It is intended to provide a crosslinked product.

  The present inventors, as a result of earnest research to achieve the above object, found that the above object can be achieved by setting the amount of the anionic emulsifier contained in the acrylic rubber within a specific range, and completed the present invention. Came to let me.

That is, according to the present invention, an acrylic rubber having an anionic emulsifier content of 10 ppm by weight or more and 4,500 ppm by weight or less is provided.
In the acrylic rubber of the present invention, the content of the nonionic emulsifier is preferably 10 weight ppm or more and 20,000 weight ppm or less, more preferably 10 weight ppm or more and 15,000 weight ppm or less.
The content of the coagulant in the acrylic rubber of the present invention is preferably 10 weight ppm or more and 9,000 weight ppm or less, and more preferably 10 weight ppm or more and 3,500 weight ppm or less.
The content of the lubricant in the acrylic rubber of the present invention is preferably 0.1 to 0.4% by weight, and more preferably 0.2 to 0.3% by weight.
The acrylic rubber of the present invention preferably has an antioxidant content of 500 ppm by weight or more, and more preferably 12,000 ppm by weight or less.
The acrylic rubber of the present invention preferably has an acrylic rubber component content of 95% by weight or more.
The acrylic rubber of the present invention preferably contains a monomer unit having a halogen atom.

Further, according to the present invention, there is provided a method for producing the acrylic rubber, which comprises emulsion-polymerizing a monomer for forming the acrylic rubber in the presence of an anionic emulsifier to obtain an emulsion polymerization solution. Provided is a method for producing an acrylic rubber, which comprises a polymerization step and a coagulation step of obtaining a hydrous crumb by adding a coagulant to the emulsion polymerization liquid to coagulate it.
In the method for producing an acrylic rubber of the present invention, it is preferable that emulsion polymerization of the monomer in the emulsion polymerization step is performed in the presence of a nonionic emulsifier and the anionic emulsifier.
In the method for producing an acrylic rubber of the present invention, it is preferable to further include an adding step of adding the lubricant and the antioxidant to the emulsion polymerization liquid before coagulation.
In the method for producing an acrylic rubber of the present invention, it is preferable to further include an adding step of adding the lubricant and the ethylene oxide polymer to the emulsion polymerization liquid before coagulation.
In the method for producing an acrylic rubber of the present invention, it is preferable to further include an adding step of adding the antioxidant and the ethylene oxide polymer to the emulsion polymerization liquid before coagulation.
In the method for producing an acrylic rubber of the present invention, it is preferable that the emulsion polymerization liquid before coagulation further comprises an addition step of adding the lubricant, the antioxidant and the ethylene oxide polymer.

  Further, according to the present invention, there are provided an acrylic rubber composition containing the above acrylic rubber and a crosslinking agent, and a rubber crosslinked product obtained by crosslinking the acrylic rubber composition.

  According to the present invention, high tensile strength, compression set resistance, and acrylic rubber giving a rubber crosslinked product excellent in water resistance, and obtained using such an acrylic rubber, high tensile strength, resistance to It is possible to provide a rubber cross-linked product having excellent compression set and water resistance.

<Acrylic rubber>
The acrylic rubber of the present invention comprises a (meth) acrylic acid ester monomer [acrylic acid as a main component (in the present invention, one having 50% by weight or more in all rubber monomer units) in the molecule. Means ester monomer and / or methacrylic acid ester monomer. Hereinafter, the same applies to methyl (meth) acrylate and the like. ] It is a rubber-like polymer containing units, and the content of the anionic emulsifier is 10 weight ppm or more and 4,500 weight ppm or less.

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

  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, (meth) acrylic acid methyl, ( 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 and n-butyl acrylate are 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 of the present invention is usually 50 to 99.9% by weight, preferably 60 to 99.5% by weight, more preferably 70 to 99. It is 5% by weight. If the content of the (meth) acrylic acid ester monomer unit is too small, the weather resistance, heat resistance, and oil resistance of the obtained rubber cross-linked product may decrease, while if it is too large, the rubber cross-linking obtained. The heat resistance of the product may decrease.

  In the acrylic rubber of the present invention, as the (meth) acrylic acid ester monomer unit, 30 to 100% by weight of a (meth) acrylic acid alkyl ester monomer unit, and a (meth) acrylic acid alkoxyalkyl ester monomer It is preferable to use a body unit consisting of 70 to 0% by weight.

  The acrylic rubber of the present invention may contain a crosslinkable monomer unit, if necessary, in addition to the (meth) acrylic acid alkyl ester monomer unit. The crosslinkable monomer forming the crosslinkable monomer unit is not particularly limited, but is, for example, an α, β-ethylenically unsaturated carboxylic acid monomer; a monomer having an epoxy group; a halogen atom. Monomers; diene monomers; and the like. Among these, from the viewpoint that the effect of improving the properties is large by setting the content of the anionic emulsifier within the predetermined range of the present invention, a unit of a monomer having a halogen atom is used as the crosslinkable monomer unit. The one containing is preferable.

  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. By using the α, β-ethylenically unsaturated carboxylic acid monomer, the acrylic rubber can be made into a carboxyl group-containing acrylic rubber having a carboxyl group as a cross-linking point. The compression set resistance can be further improved.

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 monoester having an alicyclic structure such as acid monocyclohexenyl; itaconic acid monoester such as monomethyl itaconate, monoethyl itaconate, mono-n-butyl itaconate, monocyclohexyl itaconate; and the like.
Among these, monoesters of α, β-ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms and alkanol having 1 to 8 carbon atoms are preferable, butenedionic acid mono-chain alkyl ester or butenedione having an alicyclic structure. Acid monoesters are more preferable, mono-n-butyl fumarate, mono-n-butyl maleate, monocyclohexyl fumarate, and monocyclohexyl maleate are more preferable, and mono-n-butyl fumarate is particularly preferable. These α, β-ethylenically unsaturated carboxylic acid monomers may 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.

  The monomer having an epoxy group is not particularly limited, and examples thereof include epoxy group-containing (meth) acrylic acid ester such as glycidyl (meth) acrylate; epoxy group-containing ether such as allyl glycidyl ether and vinyl glycidyl ether; Is mentioned.

  The monomer having a halogen atom is not particularly limited, and examples thereof include unsaturated alcohol esters of halogen-containing saturated carboxylic acid, (meth) acrylic acid haloalkyl ester, (meth) acrylic acid haloacyloxyalkyl ester, (meth) acrylic acid. 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 the (meth) acrylic acid haloalkyl ester 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 (meth) acrylic acid haloacyloxyalkyl ester include 2- (chloroacetoxy) ethyl (meth) acrylate, 2- (chloroacetoxy) propyl (meth) acrylate, and 3- (chloro) (meth) acrylic acid. 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. Is mentioned.

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.

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, piperylene and the like.
Specific examples of the non-conjugated diene monomer include ethylidene norbornene, dicyclopentadiene, dicyclopentadienyl (meth) acrylate, and 2-dicyclopentadienylethyl (meth) acrylate. ..

  Among the above-mentioned crosslinkable monomers, when an α, β-ethylenically unsaturated carboxylic acid monomer is used, the acrylic rubber can be a carboxyl group-containing acrylic rubber. By using a carboxyl group-containing acrylic rubber as the acrylic rubber, it is possible to further improve the compression set resistance while improving the oil resistance and heat resistance. Further, among the above-mentioned crosslinkable monomers, when a monomer having a halogen atom is used, the acrylic rubber can be a halogen atom-containing acrylic rubber. When the acrylic rubber is a halogen-containing acrylic rubber, the tensile strength can be further increased while the oil resistance and heat resistance are good.

  The content of the crosslinkable monomer unit in the acrylic rubber of the present invention 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. Is. By setting the content of the crosslinkable monomer unit in the above range, it is possible to more appropriately enhance the compression set resistance while improving the mechanical properties and heat resistance of the obtained rubber crosslinked product.

  The acrylic rubber of the present invention has, in addition to the (meth) acrylic acid ester monomer unit and the crosslinkable monomer unit optionally used, a unit of another monomer copolymerizable therewith. You may have. Such other copolymerizable monomers include aromatic vinyl monomers, α, β-ethylenically unsaturated nitrile monomers, acrylamide monomers, and other olefin monomers. Can be mentioned.

  Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, divinylbenzene and the like.

Examples of the α, β-ethylenically unsaturated nitrile monomer include acrylonitrile and methacrylonitrile.
Examples of the acrylamide-based monomer include acrylamide and methacrylamide.
Other olefinic monomers include ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl acetate, ethyl vinyl ether, butyl vinyl ether and the like.

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

  The other copolymerizable monomer may be used alone or in combination of two or more. The content of these copolymerizable other monomer units in the acrylic rubber of the present invention is usually 49.9% by weight or less, preferably 39.5% by weight or less, more preferably 29.5% by weight. % Or less.

  The acrylic rubber of the present invention has an anionic emulsifier content of 10 wt ppm or more and 4,500 wt ppm or less, preferably 500 wt ppm or more and 4,400 wt ppm or less, more preferably 4, It is 300 ppm by weight or less, more preferably 4,000 ppm by weight or less. The acrylic rubber of the present invention is obtained by emulsion-polymerizing the above-mentioned monomers, but an emulsifier is usually used in the emulsion-polymerization. Then, in the present invention, the viewpoint of excellent emulsification action, the viewpoint of being able to effectively prevent the generation of stains due to the adhesion of aggregates due to the polymerization to the polymerization apparatus (for example, the polymerization tank) during emulsion polymerization, and Uses an anionic emulsifier as such an emulsifier from the viewpoint of improving the coagulability of the emulsion-polymerized liquid obtained by the polymerization and thereby enabling coagulation with a relatively small amount of coagulant. .. In such a situation, the present inventors focused their attention on the anionic emulsifier remaining in the acrylic rubber, and conducted diligent studies. As a result, the residual amount (content) of the anionic emulsifier in the acrylic rubber was 4,500. The present invention has been found to find that a crosslinked rubber obtained by using such an acrylic rubber has high tensile strength, excellent compression set resistance, and excellent water resistance by controlling the content to be ppm by weight or less. It has been completed. The content of the anionic emulsifier can be determined, for example, from the peak area of the molecular weight corresponding to the anionic emulsifier in the measurement chart obtained by GPC measurement of acrylic rubber. The content of the anionic emulsifier may be 4,500 ppm by weight or less, and the lower limit thereof is 10 ppm by weight or more, preferably 500 ppm by weight or more. By setting the content of the anionic emulsifier to preferably 500 ppm by weight or more, the tensile strength may be increased depending on the kind of the crosslinkable group contained in the acrylic rubber (for example, when the crosslinkable group is a halogen atom). It is preferable because it can be further increased.

  The anionic emulsifier is not particularly limited, and examples thereof include salts of fatty acids such as myristic acid, palmitic acid, oleic acid, and linolenic acid, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, and higher alcohol sulfates such as sodium lauryl sulfate. Examples thereof include ester salts, higher phosphate ester salts such as sodium alkyl phosphate ester, and alkyl sulfosuccinates. Among these anionic emulsifiers, higher phosphate ester salts and higher alcohol sulfate ester salts are preferable. These anionic emulsifiers can be used alone or in combination of two or more.

  The acrylic rubber of the present invention contains an anionic emulsifier as described above, but the content of the acrylic rubber component in the acrylic rubber of the present invention is preferably 95% by weight or more, It is preferably 97% by weight or more, and more preferably 98% by weight or more. That is, it can be said that the acrylic rubber of the present invention is an acrylic rubber composition containing preferably 95% by weight or more (more preferably 97% by weight or more, further preferably 98% by weight) of an acrylic rubber component.

<Method for producing acrylic rubber>
The acrylic rubber of the present invention can be manufactured, for example, by the following manufacturing method. That is,
In the presence of an anionic emulsifier, by emulsion polymerization of a monomer for forming an acrylic rubber, an emulsion polymerization step to obtain an emulsion polymerization liquid,
A coagulation step of adding a coagulant to the emulsion polymerization liquid to obtain a hydrous crumb,
A washing step of washing the hydrous crumb,
A drying step of drying the washed hydrous crumb,
Can be manufactured by the method for manufacturing an acrylic rubber.

<Emulsion polymerization step>
The emulsion polymerization step in the above production method is a step of obtaining an emulsion polymerization liquid by emulsion-polymerizing a monomer for forming an acrylic rubber in the presence of an anionic emulsifier.

  An ordinary method may be used as the emulsion polymerization method in the emulsion polymerization step. The anionic emulsifier is not particularly limited, and the above-mentioned ones can be used without limitation. The amount of the anionic emulsifier used is preferably 0.1 to 100 parts by weight of the monomer used for the polymerization, from the viewpoint that the amount of the anionic emulsifier remaining in the obtained acrylic rubber is within the above range. 2.0 parts by weight, more preferably 0.2 to 1.9 parts by weight, even more preferably 0.3 to 1.8 parts by weight, even more preferably 0.3 to 0.75 parts by weight, particularly preferably 0. .35 to 0.65 parts by weight.

  In addition, in the emulsion polymerization step, it is preferable to use, in addition to the anionic emulsifier, an emulsifier other than the anionic emulsifier, such as a nonionic emulsifier or a cationic emulsifier, as an emulsifier in the emulsion polymerization step.

  The nonionic emulsifier is not particularly limited, and examples thereof include polyoxyethylene alkyl ethers such as polyoxyethylene dodecyl ether, polyoxyethylene alkylphenol ethers such as polyoxyethylene nonylphenyl ether, and polyoxyethylene stearic acid ester. Examples thereof include ethylene alkyl ester, polyoxyethylene sorbitan alkyl ester, and polyoxyethylene polyoxypropylene copolymer. Among these nonionic emulsifiers, polyoxyethylene polypropylene glycol, polyethylene glycol monostearate, polyoxyethylene alkyl ether, and polyoxyethylene alkylphenol ether are preferable. The nonionic emulsifier preferably has a weight average molecular weight of less than 10,000, more preferably has a weight average molecular weight of 500 to 8,000, and further preferably has a weight average molecular weight of 600 to 5,000. The cationic emulsifier is not particularly limited, and examples thereof include alkyltrimethylammonium chloride, dialkylammonium chloride, benzylammonium chloride and the like. Emulsifiers other than these anionic emulsifiers can be used alone or in combination of two or more.

  Among the emulsifiers other than these anionic emulsifiers, it is preferable to use nonionic emulsifiers. That is, in the emulsion polymerization step, it is preferable to use a combination of an anionic emulsifier and a nonionic emulsifier, whereby the emulsifying action can be further enhanced, and the emulsification can be performed better, and the anionic emulsifier can be used. Even when the amount used is within the above range, it is possible to more appropriately prevent the generation of stains due to the adhesion of the polymer or the like to the polymerization apparatus (for example, the polymerization tank) during emulsion polymerization. Therefore, as a result, it becomes possible to more appropriately reduce the amount of the anionic emulsifier contained in the obtained acrylic rubber.

  When the anionic emulsifier and the nonionic emulsifier are used in combination, the amount of the nonionic emulsifier used is preferably more than 0 parts by weight and 4 parts by weight or less, more preferably 100 parts by weight of the monomer used for the polymerization. The amount is 0.1 to 3 parts by weight, more preferably 0.5 to 2 parts by weight, and particularly preferably 0.7 to 1.7 parts by weight. When used in combination with an anionic emulsifier and a nonionic emulsifier, the weight ratio of the anionic emulsifier / nonionic emulsifier is preferably 1/99 to 99/1, more preferably 20/80 to 90/10. 25/75 to 75/25 are more preferable, 50/50 to 75/25 are still more preferable, and 65/35 to 75/25 are particularly preferable.

  In addition, in the emulsion polymerization in the emulsion polymerization step, in addition to an emulsifier containing an anionic emulsifier, a polymerization initiator, a polymerization terminator and the like can be used according to a standard method.

  As the polymerization initiator, azo compounds such as azobisisobutyronitrile; organic peroxides such as diisopropylbenzene hydroperoxide, cumene hydroperoxide, paramenthane hydroperoxide, benzoyl peroxide; sodium persulfate, persulfate Inorganic peroxides such as potassium, hydrogen peroxide and ammonium persulfate; and the like can be used. These polymerization initiators can be used alone or in combination of two or more kinds. The amount of the polymerization initiator used is preferably 0.001 to 1.0 part by weight with respect to 100 parts by weight of the monomer used for the polymerization.

  Moreover, it is preferable to use an organic peroxide and an inorganic peroxide as a polymerization initiator in combination with a reducing agent, as a redox polymerization initiator. The reducing agent used in combination is not particularly limited, but a compound containing a metal ion in a reduced state such as ferrous sulfate, sodium hexamethylenediaminetetraacetate, cuprous naphthenate; ascorbic acid, sodium ascorbate , Ascorbic acid (salt) such as potassium ascorbate; erythorbic acid (salt) such as erythorbic acid, sodium erysorbate, and potassium erysorbate; saccharides; sulfinates such as sodium hydroxymethanesulfinate; sodium sulfite, potassium sulfite, sulfite Sodium hydrogen, sodium aldehyde sulfite, potassium hydrogen sulfite sulfite; sodium pyrosulfite, potassium pyrosulfite, sodium pyrobisulfite, potassium pyrosulfite, etc. pyrosulfite; sodium thiosulfate, potassium thiosulfate, etc. thiosulfate Phosphorous acid, sodium phosphite, potassium phosphite, sodium hydrogen phosphite, potassium phosphite (salt); pyrophosphorous acid, sodium pyrophosphite, potassium pyrophosphite, sodium pyrophosphite, pyrophosphite Pyrophosphorous acid (salt) such as potassium hydrogen phosphate; sodium formaldehyde sulfoxylate and the like. These reducing agents can be used alone or in combination of two or more. The amount of the reducing agent used is preferably 0.0003 to 0.5 part by weight, based on 100 parts by weight of the monomer used for the polymerization.

  Examples of the polymerization terminator include hydroxylamine, hydroxyamine sulfate, diethylhydroxyamine, hydroxyaminesulfonic acid and its alkali metal salts, sodium dimethyldithiocarbamate, hydroquinone and the like. The amount of the polymerization terminator used is not particularly limited, but is preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the monomer used for the polymerization.

  The amount of water used is preferably 80 to 500 parts by weight, more preferably 100 to 300 parts by weight, based on 100 parts by weight of the monomer used for polymerization.

  At the time of emulsion polymerization, a polymerization auxiliary material such as a molecular weight adjusting agent, a particle size adjusting agent, a chelating agent and an oxygen scavenger can be used, if necessary.

  The emulsion polymerization may be carried out by any of batch method, semi-batch method and continuous method, but the semi-batch method is preferred. Specifically, in a reaction system containing a polymerization initiator and a reducing agent, a monomer used for the polymerization is continuously dropped into the polymerization reaction system from the start of the polymerization reaction to an arbitrary time, and the polymerization reaction is performed. At least one of the monomers used for the polymerization, the polymerization initiator, and the reducing agent is preferably subjected to the polymerization reaction while being continuously added dropwise to the polymerization reaction system from the initiation of the polymerization reaction to an arbitrary time, It is more preferable to carry out the polymerization reaction while continuously dropping all of the monomers, the polymerization initiator and the reducing agent used for the polymerization from the start of the polymerization reaction to an arbitrary time. By carrying out the polymerization reaction while continuously dropping these, emulsion polymerization can be stably carried out, whereby the polymerization reaction rate can be improved. The polymerization is usually carried out in the temperature range of 0 to 70 ° C, preferably 5 to 50 ° C.

  When the polymerization reaction is carried out while continuously dropping the monomer used for the polymerization, the monomer used for the polymerization is mixed with an emulsifier containing an anionic emulsifier and water to prepare a state of a monomer emulsion. It is preferable that the monomer emulsion is continuously added dropwise. The method for preparing the monomer emulsion is not particularly limited, and the total amount of the monomers used for the polymerization, the total amount of the emulsifier containing the anionic emulsifier, and water are mixed using a stirrer such as a homomixer or a disk turbine. Examples include a method of stirring. The amount of water used in the monomer emulsion is preferably 10 to 70 parts by weight, more preferably 20 to 50 parts by weight, based on 100 parts by weight of the monomer used for the polymerization.

  When the polymerization reaction is continuously carried out while continuously dropping into the polymerization reaction system from the initiation of the polymerization reaction to an arbitrary time for all of the monomers used for the polymerization, the polymerization initiator, and the reducing agent, these are separated from each other. May be added dropwise to the polymerization system by using the dropping device, or at least the polymerization initiator and the reducing agent are mixed in advance and, if necessary, added to the polymerization system from the same dropping device as an aqueous solution state. May be. After completion of the dropping, the reaction may be continued for an arbitrary time in order to further improve the polymerization reaction rate.

<Coagulation process>
The coagulation step in the above production method is a step of obtaining a hydrous crumb by adding a coagulant to the emulsion polymerization liquid obtained in the emulsion polymerization step.

  The coagulant is not particularly limited, but examples thereof include a monovalent to trivalent metal salt. The monovalent to trivalent metal salt is a salt containing a metal that becomes a monovalent to trivalent metal ion when dissolved in water, and is not particularly limited, and examples thereof include an inorganic acid selected from hydrochloric acid, nitric acid, sulfuric acid and the like. And a salt of an organic acid such as acetic acid and a metal selected from sodium, potassium, lithium, magnesium, calcium, zinc, titanium, manganese, iron, cobalt, nickel, aluminum and tin. Further, hydroxides of these metals can also be used.

  Specific examples of the monovalent to trivalent metal salts include sodium chloride, potassium chloride, lithium chloride, magnesium chloride, calcium chloride, zinc chloride, titanium chloride, manganese chloride, iron chloride, cobalt chloride, nickel chloride, aluminum chloride and chloride. Metal chlorides such as tin; sodium nitrate, potassium nitrate, lithium nitrate, magnesium nitrate, calcium nitrate, zinc nitrate, titanium nitrate, manganese nitrate, iron nitrate, cobalt nitrate, nickel nitrate, aluminum nitrate, tin nitrate and other nitrates; sodium sulfate , Potassium sulfate, lithium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, titanium sulfate, manganese sulfate, iron sulfate, cobalt sulfate, nickel sulfate, aluminum sulfate, tin sulfate and the like; and the like. Among these, calcium chloride, sodium chloride, aluminum sulfate, magnesium chloride, magnesium sulfate, zinc chloride, zinc sulfate and sodium sulfate are preferable. Among them, monovalent or divalent metal salts are preferable, more preferable are calcium chloride, sodium chloride, magnesium sulfate and sodium sulfate, and further preferable are magnesium sulfate and sodium sulfate. Moreover, these can be used individually by 1 type or in combination of 2 or more types.

  The amount of the coagulant used is preferably 1 to 100 parts by weight, more preferably 2 to 40 parts by weight, further preferably 3 to 20 parts by weight, and particularly preferably 100 parts by weight of the acrylic rubber component in the emulsion polymerization liquid. Is 3 to 12 parts by weight. According to the present invention, by using an anionic emulsifier as an emulsifier used when performing emulsion polymerization, good coagulation of acrylic rubber is achieved even when the amount of the coagulant used is relatively small as described above. Is what you can do. And by this, the amount of the coagulant remaining in the obtained acrylic rubber can be appropriately reduced, and the deterioration of various characteristics due to the residual coagulant can be effectively prevented.

  The solidification temperature is not particularly limited, but is preferably 50 to 90 ° C, more preferably 60 to 90 ° C.

  Further, when producing the acrylic rubber of the present invention, a part of the compounding agents to be compounded into the acrylic rubber, specifically, the At least one of the inhibitor, the lubricant and the ethylene oxide polymer is preferably contained in advance. That is, it is preferable that at least one of the antioxidant, the lubricant, and the ethylene oxide polymer is already mixed in the emulsion polymerization liquid, and the emulsion polymerization liquid containing these components is solidified.

  For example, by preliminarily containing an antiaging agent in the emulsion polymerization liquid before coagulation, deterioration of the acrylic rubber due to heat during drying in the drying step described later can be effectively suppressed. Specifically, it is possible to effectively suppress the decrease in Mooney viscosity due to deterioration due to heating during drying, and further, in the case of using a rubber cross-linked product, the normal tensile strength and elongation at break are effective. It can be increased. In addition, in the state of the emulsion polymerization liquid before performing the coagulation, by adding an antioxidant, since it is possible to appropriately disperse the antioxidant, even when the amount of the antioxidant is reduced, The effect of addition can be sufficiently exhibited. Specifically, the amount of the antioxidant added is preferably 0.1 to 2 parts by weight, more preferably 0.2 to 1.2 parts by weight, based on 100 parts by weight of the acrylic rubber component in the emulsion polymerization liquid. Even with a relatively small blending amount, the effect of addition can be sufficiently exhibited. Incidentally, even when the anti-aging agent is contained in the emulsion polymerization liquid before coagulation, in the subsequent coagulation and washing, drying, etc., the added anti-aging agent is not substantially removed. The addition effect can be sufficiently exhibited. Further, as a method of containing an anti-aging agent in the emulsion polymerization liquid, after the emulsion polymerization, and a method of adding to the emulsion polymerization liquid before performing the coagulation, or a method of adding to the solution before performing the emulsion polymerization However, when added to the solution before carrying out the emulsion polymerization, because there is a possibility that stains of the polymerization apparatus may occur, after the emulsion polymerization, and in the emulsion polymerization liquid before performing the coagulation The addition method is preferred.

  The antiaging agent is not particularly limited, but 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butylphenol, butylhydroxyanisole, 2,6-di-t-butyl- α-dimethylamino-p-cresol, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, styrenated phenol, 2,2′-methylene-bis (6-α-methyl- Benzyl-p-cresol), 4,4'-methylenebis (2,6-di-t-butylphenol), 2,2'-methylene-bis (4-methyl-6-t-butylphenol), 3- (3,3. 5-Di-tert-butyl-4-hydroxyphenyl) stearyl propionate, alkylated bisphenols, butylated sulfur-free phenolic antioxidants such as butylated reaction products of p-cresol and dicyclopentadiene; 2,4 -Bis [(octylthio) methyl] -6-methylphenol, 2,2'-thiobis- (4-methyl-6-t-butylphenol), 4,4'-thiobis- (6-t-butyl-o-cresol ), 2,6-di-t-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol, and other thiophenol-based antioxidants; tris (nonylphenyl) ) Phosphite-based antioxidants such as phosphite, diphenylisodecyl phosphite, and tetraphenyldipropylene glycol / diphosphite; sulfur ester-based antioxidants such as dilauryl thiodipropionate; phenyl-α-naphthylamine, phenyl-β -Naphthylamine, p- (p-toluenesulfonylamide) -diphenylamine, 4,4 '-(α, α-dimethylbenzyl) diphenylamine, N, N-diphenyl-p-phenylenediamine, N-isopropyl-N'-phenyl- Amine-based antioxidants such as p-phenylenediamine and butyraldehyde-aniline condensates; 2-mercaptobenzimidazole and other imidazole antioxidants; 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline And a quinoline antiaging agent such as; a hydroquinone antiaging agent such as 2,5-di- (t-amyl) hydroquinone; and the like. These antiaging agents may be used alone or in combination of two or more.

  Further, by preliminarily containing the lubricant in the emulsion polymerization liquid before coagulation, the resulting acrylic rubber can contain the lubricant in a well-dispersed state, and as a result, the obtained acrylic rubber It is possible to appropriately reduce the tackiness of the composition, and thus, it is possible to prevent adhesion to a dryer during drying, improve operability during drying, and obtain an acrylic rubber composition. In this case, the roll processability can be improved. The amount of the lubricant added is preferably 0.1 to 0.4 parts by weight, more preferably 0.15 to 0.3 parts by weight, and further preferably 0, relative to 100 parts by weight of the acrylic rubber component in the emulsion polymerization liquid. 0.2 to 0.3 parts by weight. Even when the lubricant is contained in the emulsion polymerization liquid before coagulation, in the subsequent coagulation, washing, drying, etc., the lubricant preliminarily blended is not substantially removed, and therefore, in the emulsion polymerization liquid. Even if it is contained, the effect of its addition can be sufficiently exhibited.

  The lubricant is not particularly limited, and examples thereof include phosphoric acid ester, fatty acid ester, fatty acid amide, and higher fatty acid. Further, as a method of containing a lubricant in the emulsion polymerization liquid, after the emulsion polymerization, and a method of adding to the emulsion polymerization liquid before performing the coagulation, or a method of adding to the solution before performing the emulsion polymerization. Be done.

  Furthermore, by preliminarily containing the ethylene oxide polymer in the emulsion polymerization liquid before solidification, the solidification property of the emulsion polymerization liquid can be improved, thereby reducing the amount of the coagulant in the solidification step. Therefore, the residual amount in the finally obtained acrylic rubber can be reduced, and the deterioration of various characteristics due to the residual coagulant can be effectively prevented. The ethylene oxide polymer may be a polymer having a polyethylene oxide structure as a main chain structure, and is not particularly limited, and examples thereof include polyethylene oxide, polypropylene oxide, ethylene oxide / propylene oxide copolymer, and the like. Polyethylene oxide is preferred. The blending amount of the ethylene oxide polymer is preferably 0.01 to 1 part by weight, more preferably 0.01 to 0.6 part by weight, and still more preferably 100 parts by weight of the acrylic rubber component in the emulsion polymerization liquid. 0.02 to 0.5 part by weight. The weight average molecular weight of the ethylene oxide polymer is preferably 10,000 to 1,000,000, more preferably 10,000 to 200,000, and further preferably 20,000 to 120,000. As a method of incorporating the ethylene oxide polymer into the emulsion polymerization liquid, a method of adding the ethylene oxide polymer to the emulsion polymerization liquid after the emulsion polymerization and before the coagulation or a solution before performing the emulsion polymerization is added. There is a method.

  The order of addition when the emulsion polymerization liquid before coagulation contains an antioxidant, a lubricant and an ethylene oxide polymer in advance is not particularly limited and may be appropriately selected.

  Then, even when these antioxidants, lubricants and / or ethylene oxide polymers are previously contained in the emulsion polymerization liquid before solidification, the coagulant is added to the emulsion polymerization liquid under the same conditions as above. By carrying out the coagulation operation in this way, a hydrous crumb can be obtained.

<Washing process>
The washing step in the above manufacturing method is a step of washing the hydrous crumb obtained in the above coagulation step.

  The washing method is not particularly limited, but a method in which water is used as a washing liquid and the added water is mixed with the water-containing crumb to perform washing with water can be mentioned. The temperature at the time of washing with water is not particularly limited, but is preferably 5 to 60 ° C, more preferably 10 to 50 ° C, and the mixing time is 1 to 60 minutes, more preferably 2 to 30 minutes.

  The amount of water added to the hydrous crumb at the time of washing with water is not particularly limited, but from the viewpoint that the residual amount of the anionic emulsifier in the finally obtained acrylic rubber can be effectively reduced. The amount of water per washing with respect to 100 parts by weight of the solid content (mainly the acrylic rubber component) contained in the water-containing crumb is preferably 50 to 9,800 parts by weight, more preferably 300 to 1, It is 800 parts by weight.

  The number of times of washing with water is not particularly limited, and may be once, but from the viewpoint of reducing the residual amount of the anionic emulsifier in the finally obtained acrylic rubber, it is preferably 2 to 10 times, more preferably 3 to 8 times. From the viewpoint of reducing the residual amount of the anionic emulsifier in the finally obtained acrylic rubber, it is desirable that the number of times of water washing is large, but even if the washing is performed beyond the above range, the removal of the anionic emulsifier is removed. While the effect is small, the increase in the number of steps has a large effect on the decrease in productivity. Therefore, the number of times of washing with water is preferably within the above range.

  Further, in the above manufacturing method, after washing with water, acid washing using an acid as a washing liquid may be further performed. By carrying out acid washing, it is possible to further improve the compression set resistance in the case of forming a rubber cross-linked product, and when the acrylic rubber is a carboxyl group-containing acrylic rubber having a carboxyl group, this acid washing The effect of improving the compression set resistance is particularly great. The acid used for acid washing is not particularly limited, and sulfuric acid, hydrochloric acid, phosphoric acid, etc. can be used without limitation. In addition, in the acid washing, when the acid is added to the hydrous crumb, it is preferably added in the state of an aqueous solution, preferably pH = 6 or less, more preferably pH = 4 or less, further preferably pH = 3 or less. It is preferable to add it in the form of an aqueous solution. Further, the method of acid washing is not particularly limited, and examples thereof include a method of mixing an aqueous solution of the added acid with the hydrous crumb.

  The temperature at the time of acid washing is not particularly limited, but is preferably 5 to 60 ° C, more preferably 10 to 50 ° C, and the mixing time is 1 to 60 minutes, more preferably 2 to 30 minutes. The pH of the washing water for acid washing is not particularly limited, but is preferably pH = 6 or less, more preferably pH = 4 or less, and further preferably pH = 3 or less. The pH of the cleaning water used for acid cleaning can be determined, for example, by measuring the pH of water contained in the hydrous crumb after acid cleaning.

  It is preferable to further wash with water after performing the acid washing, and the conditions of washing with water may be the same as the above-mentioned conditions.

<Drying process>
The drying step in the above manufacturing method is a step of drying the water-containing crumbs washed in the washing step.

  The drying method in the drying step is not particularly limited, but for example, it can be dried using a dryer such as a screw type extruder, a kneader type dryer, an expander dryer, a hot air dryer or a reduced pressure dryer. .. Moreover, you may use the drying method which combined these. Further, if necessary, the water-containing crumb may be filtered using a sieve such as a rotary screen or a vibrating screen; a centrifugal dehydrator;

  For example, the drying temperature in the drying step is not particularly limited and varies depending on the dryer used for drying. For example, when a hot air dryer is used, the drying temperature is preferably 80 to 200 ° C., and 100 It is more preferable to set the temperature to ˜170 ° C.

  According to the above manufacturing method, the acrylic rubber of the present invention can be obtained as described above.

  The Mooney viscosity (ML1 + 4, 100 ° C.) (polymer Mooney) of the acrylic rubber of 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 acrylic rubber of the present invention, the residual amount of the coagulant contained in the acrylic rubber is preferably 9,000 weight ppm or less, more preferably 7,000 weight ppm or less, and further preferably 5,000 weight ppm. ppm or less, particularly preferably 3,500 ppm or less. The lower limit of the residual amount of the coagulant is not particularly limited, but it is preferably 10 ppm by weight or more. By setting the residual amount of the coagulant in the acrylic rubber within the above range, it is possible to further improve the water resistance of the rubber crosslinked product. The residual amount of the coagulant can be determined by, for example, performing elemental analysis on the acrylic rubber and measuring the content of the element contained in the coagulant. Further, the method for adjusting the residual amount of the coagulant to the above-mentioned amount is not particularly limited, and examples thereof include a method of adjusting the amount of the coagulant added to the above-described range, and a method of adjusting the washing condition as described above. ..

  Further, in the acrylic rubber of the present invention, the residual amount of the nonionic emulsifier contained in the acrylic rubber is preferably 20,000 weight ppm or less, more preferably 18,000 weight ppm or less, further preferably 15 weight ppm or less. It is 3,000 ppm by weight or less, particularly preferably 13,000 ppm by weight or less. The lower limit of the residual amount of the nonionic emulsifier is not particularly limited, but is preferably 10 ppm by weight or more. By setting the residual amount of the nonionic emulsifier in the above range, the effects of the present invention, particularly the effects of improving tensile strength, compression set resistance, and water resistance, can be further enhanced. The residual amount of the nonionic emulsifier can be determined, for example, from the peak area of the molecular weight corresponding to the nonionic emulsifier in the measurement chart obtained by GPC measurement of acrylic rubber.

  In the acrylic rubber of the present invention, the residual amount of the lubricant contained in the acrylic rubber is preferably 0.1 to 0.4% by weight, more preferably 0.15 to 0.3% by weight, and further preferably 0. 0.2 to 0.3% by weight. By setting the residual amount of the lubricant within the above range, it is possible to more effectively enhance the handling property of the acrylic rubber during drying and the roll processability while suppressing the occurrence of bleeding. The residual amount of the lubricant can be determined by dissolving acrylic rubber in tetrahydrofuran and performing GPC measurement using tetrahydrofuran as a developing solvent. Specifically, from the chart obtained by GPC measurement, the integrated value of the peak corresponding to the molecular weight of the lubricant is obtained, and this integrated value is compared with the integrated value of the peak of acrylic rubber, and these integrated values are associated. The content of the lubricant can be determined by determining the weight ratio from the molecular weight of the lubricant.

  Furthermore, in the acrylic rubber of the present invention, the residual amount of the antioxidant contained in the acrylic rubber is preferably 500 ppm by weight or more, more preferably 1,000 ppm by weight or more, further preferably 2,000 ppm by weight. That is all. The upper limit of the content of the antioxidant is not particularly limited, but it is preferably 12,000 ppm by weight or less. By setting the residual amount of the antioxidant within the above range, it is possible to more appropriately prevent deterioration due to drying, and it is possible to further increase the tensile strength of the obtained rubber cross-linked product. The residual amount of the anti-aging agent can be obtained, for example, from the peak area of the molecular weight corresponding to the anti-aging agent in the measurement chart obtained by performing GPC measurement on acrylic rubber.

<Acrylic rubber composition>
The acrylic rubber composition of the present invention is obtained by blending the above-mentioned acrylic rubber of the present invention with a crosslinking agent.

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

  Among these, when the acrylic rubber of the present invention has an α, β-ethylenically unsaturated carboxylic acid monomer unit as a crosslinkable monomer unit, a polyvalent amine compound as a crosslinking agent, and It is preferable to use the carbonate. Further, when the acrylic rubber of the present invention has a unit of a monomer having a halogen atom as a crosslinkable monomer unit, sulfur, a sulfur donor, or a triazine thiol compound may be used as a crosslinking agent. preferable.

  The polyvalent amine compound and the carbonate thereof are not particularly limited, but the polyvalent amine compound having 4 to 30 carbon atoms and the carbonate thereof are preferable. Examples of such polyvalent amine compounds and their carbonates include aliphatic polyamine compounds, their carbonates, and aromatic polyamine compounds.

  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.

  Although it does not specifically limit as an aromatic polyvalent amine compound, For example, 4,4'- methylene dianiline, p-phenylenediamine, m-phenylenediamine, 4,4'-diamino diphenyl ether, 3,4'-diamino diphenyl ether. 4,4 '-(m-phenylenediisopropylidene) dianiline, 4,4'-(p-phenylenediisopropylidene) dianiline, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 4,4'-diaminobenzanilide, 4,4'-bis (4-aminophenoxy) biphenyl, m-xylylenediamine, p-xylylenediamine, 1,3,5-benzenetriamine and the like can be mentioned. Among these, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane is preferable.

  The sulfur donor is not particularly limited, and examples thereof include dipentamethylene thiuram hexasulfide and triethyl thiuram disulfide.

The triazine thiol compound is not particularly limited, but for example, 1,3,5-triazine-2,4,6-trithiol, 6-anilino-1,3,5-triazine-2,4-dithiol, 6-dibutyl. Amino-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 and the like. Among these, 1,3,5-triazine-2,4,6-trithiol is preferable.

  The content of the crosslinking agent in the acrylic rubber composition of the present invention is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and particularly preferably 0.1 to 100 parts by weight of the acrylic rubber. 2 to 4 parts by weight. By setting the content of the cross-linking agent within the above range, it is possible to make the rubber cross-linking material excellent in mechanical strength as a rubber cross-linked product.

  Further, the acrylic rubber composition of the present invention preferably further contains a crosslinking accelerator. The cross-linking accelerator is not particularly limited, but when the acrylic rubber of the present invention has a carboxyl group as a cross-linkable group, and the cross-linking agent is a polyvalent amine compound or a carbonate thereof, , Guanidine compounds, diazabicycloalkene compounds, imidazole compounds, quaternary onium salts, tertiary phosphine compounds, aliphatic monovalent secondary amine compounds, and aliphatic monovalent tertiary amine compounds. Among these, guanidine compounds, diazabicycloalkene compounds, and aliphatic monovalent secondary amine compounds are preferable, and guanidine compounds are particularly preferable. These basic crosslinking accelerators can be used alone or in combination of two or more.

  Specific examples of the guanidine compound include 1,3-di-o-tolylguanidine and 1,3-diphenylguanidine. Specific examples of the diazabicycloalkene compound include 1,8-diazabicyclo [5.4.0] unde-7-cene and 1,5-diazabicyclo [4.3.0] no-5-ene. .. Specific examples of the imidazole compound include 2-methylimidazole and 2-phenylimidazole. Specific examples of the quaternary onium salt include tetra n-butyl ammonium bromide and octadecyl tri n-butyl ammonium bromide. Specific examples of the tertiary phosphine compound include triphenylphosphine and tri-p-tolylphosphine.

  The aliphatic monovalent secondary amine compound is a compound obtained by substituting two hydrogen atoms of ammonia with an aliphatic hydrocarbon group. The aliphatic hydrocarbon group substituting the hydrogen atom preferably has 1 to 30 carbon atoms. Specific examples of the aliphatic monovalent secondary amine compound include dimethylamine, diethylamine, dipropylamine, diallylamine, diisopropylamine, di-n-butylamine, di-t-butylamine, di-sec-butylamine, dihexylamine and dihexylamine. Heptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine, ditridecylamine, ditetradecylamine, dipentadecylamine, dicetylamine, di-2-ethylhexylamine, dioctadecylamine and the like.

  The aliphatic monovalent tertiary amine compound is a compound in which all three hydrogen atoms of ammonia are replaced with an aliphatic hydrocarbon group. The aliphatic hydrocarbon group substituting the hydrogen atom preferably has 1 to 30 carbon atoms. Specific examples of the aliphatic monovalent tertiary amine compound include trimethylamine, triethylamine, tripropylamine, triallylamine, triisopropylamine, tri-n-butylamine, tri-t-butylamine, tri-sec-butylamine, trihexylamine. , Triheptylamine, trioctylamine, trinonylamine, tridecylamine, triundecylamine, tridodecylamine, and the like.

  Further, when the acrylic rubber of the present invention has a halogen atom as a crosslinkable group and the crosslinking agent is sulfur or a sulfur donor, the crosslinking accelerator is sodium stearate or potassium stearate. Fatty acid metal soaps such as and the like can be used. Alternatively, when the acrylic rubber of the present invention has a halogen atom as a crosslinkable group and the crosslinking agent is a triazine thiol compound, the crosslinking accelerator includes dithiocarbamate and its derivative, thiourea. Compounds as well as thiuram sulfide compounds can be used. Among them, as the cross-linking agent, sulfur or a sulfur donor is preferable from the viewpoint of tensile strength of the obtained rubber cross-linked product, and a triazine thiol compound is preferable from the viewpoint of compression set and water resistance.

  The content of the crosslinking accelerator in the acrylic rubber composition of the present invention is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 7.5 parts by weight, based on 100 parts by weight of the acrylic rubber. Parts, particularly preferably 1 to 5 parts by weight. By setting the content of the crosslinking accelerator in the above range, the tensile strength and compression set resistance of the obtained rubber crosslinked product can be further improved.

  Further, the acrylic rubber composition of the present invention may be compounded with a compounding agent usually used in the rubber processing field, in addition to the above components. Examples of such compounding agents include reinforcing fillers such as silica and carbon black; non-reinforcing fillers such as calcium carbonate and clay; antioxidants; light stabilizers; scorch inhibitors; plasticizers; processing aids. Agents, adhesives, lubricants, lubricants, flame retardants, antifungal agents, antistatic agents, colorants, crosslinking retardants, and the like. The compounding amount of these compounding agents is not particularly limited as long as it does not impair the object and effects of the present invention, and an amount according to the compounding purpose can be appropriately compounded.

  Further, the acrylic rubber composition of the present invention may further contain a rubber, an elastomer, a resin and the like other than the above-mentioned acrylic rubber of the present invention within a range not impairing the effects of the present invention. For example, rubbers other than acrylic rubbers such as acrylic rubbers other than the above-mentioned acrylic rubber of the present invention, natural rubbers, polybutadiene rubbers, polyisoprene rubbers, styrene-butadiene rubbers, acrylonitrile-butadiene rubbers, silicone rubbers, fluororubbers; Elastomers such as elastomers, styrene elastomers, vinyl chloride elastomers, polyester elastomers, polyamide elastomers, polyurethane elastomers, polysiloxane elastomers; polyolefin resins, polystyrene resins, polyacrylic resins, polyphenylene ether resins, polyesters. A resin such as a resin, a polycarbonate resin, a polyamide resin, a vinyl chloride resin, a fluororesin, or the like can be blended. The total amount of rubber, elastomer, and resin other than the acrylic rubber of the present invention described above is preferably 50 parts by weight or less, more preferably 10 parts by weight or less, and even more preferably 100 parts by weight of the acrylic rubber. It is 1 part by weight or less.

  Acrylic rubber composition of the present invention, the acrylic rubber, a cross-linking agent, and other various compounding agents used as necessary are mixed, mixed with a Banbury mixer or a kneader, kneading, then using a kneading roll, It is prepared by further kneading.

  The mixing order of each component is not particularly limited, but after sufficiently mixing components that are difficult to react or decompose with heat, a crosslinking agent, which is a component that easily reacts or decomposes with heat, at a temperature at which reaction or decomposition does not occur. It is preferable to mix in a short time.

<Rubber cross-linked product>
The crosslinked rubber of the present invention is obtained by crosslinking the acrylic rubber composition of the present invention described above.
The rubber cross-linked product of the present invention is obtained by using the acrylic rubber composition of the present invention to perform molding with a molding machine corresponding to a desired shape, for example, an extruder, an injection molding machine, a compressor, a roll, etc., and heating. It can be produced by carrying out a cross-linking reaction to fix the shape as a rubber cross-linked product. In this case, the molding may be performed in advance and then crosslinked, or the molding and the crosslinking may be performed simultaneously. The molding temperature is usually 10 to 200 ° C, preferably 25 to 120 ° C. The crosslinking temperature is usually 130 to 220 ° C., preferably 150 to 190 ° C., and the crosslinking time is usually 2 minutes to 10 hours, preferably 3 minutes to 5 hours. As a heating method, a method used for crosslinking rubber such as press heating, steam heating, oven heating, and hot air heating may be appropriately selected.

  The rubber cross-linked product of the present invention may be further heated for secondary cross-linking depending on the shape and size of the rubber cross-linked product. The secondary crosslinking varies depending on the heating method, the crosslinking temperature, the shape, etc., but is preferably 1 to 48 hours. The heating method and heating temperature may be appropriately selected.

  The rubber cross-linked product of the present invention thus obtained is used as a sealing material such as O-rings, packings, oil seals, and bearing seals in a wide range of fields such as transportation machines such as automobiles, general equipment, and electric equipment. It is preferably used as a gasket, a cushioning material, a vibration damping material, an electric wire coating material, industrial belts, tubes and hoses, sheets, and the like.

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.

[Moonie viscosity (ML1 + 4, 100 ° C)]
The Mooney viscosity (polymer Mooney) of acrylic rubber was measured according to JIS K6300.

[Residual amount of anionic emulsifier and nonionic emulsifier]
The residual amount of the anionic emulsifier and the nonionic emulsifier in the acrylic rubber was measured by dissolving the acrylic rubber in tetrahydrofuran and performing GPC measurement using tetrahydrofuran as a developing solvent. Specifically, from the chart obtained by GPC measurement, the integrated values of the peaks corresponding to the molecular weights of the anionic emulsifier and the nonionic emulsifier used in the production were determined, and these integrated values and the integrated value of the peak of the acrylic rubber were obtained. The residual amounts of the anionic emulsifier and the nonionic emulsifier were calculated by comparing the above and the molecular weight corresponding to these integral values.

[Residual amount of coagulant]
The residual amount of the coagulant in the acrylic rubber was measured by performing elemental analysis on the acrylic rubber using ICP-AES. Specifically, the content ratio of the element contained in the used coagulant was obtained by elemental analysis, and the residual amount of the coagulant was calculated from the obtained content ratio.

[Residual amount of lubricant and anti-aging agent]
Acrylic rubber was dissolved in tetrahydrofuran, and GPC measurement was performed using tetrahydrofuran as a developing solvent to measure the residual amounts of the lubricant and the antioxidant in the acrylic rubber. Specifically, from the chart obtained by GPC measurement, the integrated values of the peaks corresponding to the molecular weights of the lubricant and the antioxidant used in the production were obtained, and these integrated values and the integrated value of the peak of the acrylic rubber were calculated. The residual amounts of the lubricant and the anti-aging agent were calculated by comparing and calculating the weight ratio from the integrated value and the corresponding molecular weight.

[Tensile strength and elongation]
The acrylic rubber composition was placed in a mold having a length of 15 cm, a width of 15 cm, and a depth of 0.2 cm, and was primary crosslinked by pressing at 170 ° C. for 20 minutes while applying a pressing pressure of 10 MPa, and then the obtained primary crosslinking The product was further heated in a gear type oven at 170 ° C. for 4 hours for secondary cross-linking to obtain a sheet-shaped rubber cross-linked product. The obtained rubber cross-linked product was punched with a No. 3 dumbbell to prepare a test piece. Next, the tensile strength and elongation in the normal state were measured using this test piece according to JIS K6251.

[Compression set]
The acrylic rubber composition was primary crosslinked by pressing it at a temperature of 170 ° C. for 20 minutes using a mold to obtain a cylindrical primary crosslinked product having a diameter of 29 mm and a height of 12.7 mm, and then obtained. The primary cross-linked product was further heated in a gear type oven at 170 ° C. for 4 hours for secondary cross-linking to obtain a columnar rubber cross-linked product. Then, the obtained rubber cross-linked product was placed in an environment of 175 ° C. for 70 hours in a state where the rubber cross-linked product was compressed by 25% according to JIS K6262, and then the compression set was measured. The smaller this value, the better the compression set resistance.

[water resistant]
The acrylic rubber composition was placed in a mold having a length of 15 cm, a width of 15 cm, and a depth of 0.2 cm, and was primary crosslinked by pressing at 170 ° C. for 20 minutes while applying a pressing pressure of 10 MPa, and then the obtained primary crosslinking The product was further heated in a gear type oven at 170 ° C. for 4 hours for secondary cross-linking to obtain a sheet-shaped rubber cross-linked product. Then, from the obtained sheet-shaped rubber cross-linked product, a test piece of 3 cm × 2 cm × 0.2 cm was cut out, and the obtained test piece was immersed in distilled water adjusted to a temperature of 80 ° C. for 70 hours in accordance with JIS K6258. An immersion test for immersion was performed, and the volume change rate of the test piece before and after immersion was measured according to the following formula. It can be judged that the smaller the volume change rate before and after the immersion, the more suppressed the swelling in water and the more excellent the water resistance.
Volume change rate before and after immersion (%) = (volume of test piece after immersion-volume of test piece before immersion) / volume of test piece before immersion x 100

[Production Example 1]
In a mixing container equipped with a homomixer, 46.294 parts of pure water, 49.3 parts of ethyl acrylate, 49.3 parts of n-butyl acrylate, 1.4 parts of mono-n-butyl fumarate, 1.4 parts as an anionic emulsifier. 0.624 parts of sodium lauryl sulfate (trade name "Emar 2FG", manufactured by Kao) and polyoxyethylene dodecyl ether (trade name "Emulgen 105", weight average molecular weight: about 1500, Kaosha) as a nonionic surfactant (Manufactured by) was charged and stirred to obtain a monomer emulsion.

  Then, 170.853 parts of pure water and 2.97 parts of the monomer emulsion obtained above were put into a polymerization reaction tank equipped with a thermometer and a stirrer, and the temperature was 12 ° C. under a nitrogen stream. Cooled down. Then, in the polymerization reaction tank, 145.44 parts of the monomer emulsion obtained above, 0.00033 part of ferrous sulfate as a reducing agent, 0.264 part of sodium ascorbate as a reducing agent, and Then, 7.72 parts of a 2.85 wt% potassium persulfate aqueous solution (0.22 parts as the amount of potassium persulfate) as a polymerization initiator was continuously added dropwise over 3 hours. Then, while maintaining the temperature in the polymerization reaction tank at 23 ° C., the reaction was continued for 1 hour, and it was confirmed that the polymerization conversion rate reached 95%. Polymerization was performed by adding hydroquinone as a polymerization terminator. The reaction was stopped and an emulsion polymerization liquid was obtained.

  Then, with respect to 100 parts of the emulsion polymerization liquid obtained by the polymerization, stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate as an antiaging agent (trade name "Irganox 1076", BASF (Manufactured by the company) 0.3 parts (total of charged monomers used when manufacturing an emulsion polymerization solution (that is, total of ethyl acrylate, n-butyl acrylate, mono-n-butyl fumarate)) to 100 parts 1 part), polyethylene oxide (weight average molecular weight (Mw) = 100,000) 0.011 part (0.036 part per 100 parts of the total amount of charged monomers used in the production of the emulsion polymerization liquid) ), And polyoxyethylene stearyl ether phosphoric acid (trade name "phosphanol RL-210", weight average molecular weight: about 500, manufactured by Toho Chemical Industry Co., Ltd.) as a lubricant, 0.075 part (when producing an emulsion polymerization liquid) A mixed solution was obtained by mixing 0.25 parts) with respect to the total 100 parts of the charged monomers used in. Then, the obtained mixed solution was transferred to a coagulation tank, 60 parts of industrial water was added to 100 parts of this mixed solution, the temperature was raised to 85 ° C., and then the mixed solution was stirred at a temperature of 85 ° C. However, 3.3 parts of sodium sulfate as a coagulant (11 parts with respect to 100 parts of the polymer contained in the mixed solution) was continuously added to solidify the polymer, whereby the acrylic rubber (A1) To obtain a hydrous crumb.

  Then, to 100 parts of the solid content of the hydrous crumb obtained above, 388 parts of industrial water was added, and the mixture was stirred at room temperature for 5 minutes in the coagulation tank, and then the water content was discharged from the coagulation tank. The crumbs were washed with water. In this production example, such washing with water was repeated 4 times.

  Then, an aqueous sulfuric acid solution (pH = 3) prepared by mixing 388 parts of industrial water and 0.13 part of concentrated sulfuric acid was added to 100 parts of the solid content of the water-containing crumb washed with water in the coagulation tank. After stirring at room temperature for 5 minutes, water was discharged from the coagulation tank to carry out pickling of the hydrous crumbs. The pH of the water-containing crumb after pickling (pH of water in the water-containing crumb) was measured to be pH = 3. Next, 388 parts of pure water was added to 100 parts of the solid content of the hydrous crumbs pickled, and the mixture was stirred at room temperature for 5 minutes in the coagulation tank, and then the water was discharged from the coagulation tank to obtain the hydrous crumbs. Was washed with pure water, and the water-containing crumb that had been washed with pure water was dried at 110 ° C. for 1 hour with a hot air drier to obtain a solid acrylic rubber (A1).

  The obtained acrylic rubber (A1) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, and the composition of the acrylic rubber (A1) is as follows: ethyl acrylate unit 49.3% by weight, n-butyl acrylate unit 49.3. %, And mono-n-butyl fumarate unit was 1.4% by weight. Regarding the acrylic rubber (A1), the residual amounts of the anionic emulsifier, the nonionic emulsifier, the coagulant, the antiaging agent, and the lubricant in the acrylic rubber (A1) were measured according to the above method. The results are shown in Table 1.

[Production Example 2]
The amount of sodium lauryl sulfate used as an anionic emulsifier was changed from 0.624 parts to 0.567 parts, and the amount of polyoxyethylene dodecyl ether used as a nonionic emulsifier was changed from 1.5 parts to 1.4 parts. A monomer emulsion was obtained in the same manner as in Production Example 1 except for the above. Then, a solid acrylic rubber (A2) was obtained in the same manner as in Production Example 1 except that the obtained monomer emulsion was used.

  The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A2) was 34, and the composition of the acrylic rubber (A2) was 49.3% by weight of ethyl acrylate unit and 49.3% of n-butyl acrylate unit. %, And mono-n-butyl fumarate unit was 1.4% by weight. Regarding the acrylic rubber (A2), the residual amounts of the anionic emulsifier, the nonionic emulsifier, the coagulant, the antiaging agent, and the lubricant in the acrylic rubber (A2) were measured according to the above method. The results are shown in Table 1.

[Production Example 3]
The amount of sodium lauryl sulfate used as an anionic emulsifier was changed from 0.624 to 0.283 parts, and the amount of polyoxyethylene dodecyl ether used as a nonionic emulsifier was changed from 1.5 parts to 1.4 parts. In addition, a monomer emulsion was obtained in the same manner as in Production Example 1, except that the number of washings with water was changed from 4 times to 8 times. Then, a solid acrylic rubber (A3) was obtained in the same manner as in Production Example 1 except that the obtained monomer emulsion was used.

  The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A3) is 34, and the composition of the acrylic rubber (A3) is as follows: ethyl acrylate unit 49.3% by weight, n-butyl acrylate unit 49.3. %, And mono-n-butyl fumarate unit was 1.4% by weight. Regarding the acrylic rubber (A3), the residual amounts of the anionic emulsifier, the nonionic emulsifier, the coagulant, the antiaging agent, and the lubricant in the acrylic rubber (A3) were measured according to the above method. The results are shown in Table 1.

[Production Example 4]
The amount of sodium lauryl sulfate used as an anionic emulsifier was changed from 0.624 parts to 0.709 parts, and the amount of polyoxyethylene dodecyl ether used as a nonionic emulsifier was changed from 1.5 parts to 1.82 parts. A monomer emulsion was obtained in the same manner as in Production Example 1 except for the above. Then, a solid acrylic rubber (A4) was obtained in the same manner as in Production Example 1 except that the obtained monomer emulsion was used.

  The acrylic rubber (A4) thus obtained has a Mooney viscosity (ML1 + 4, 100 ° C.) of 31, and the acrylic rubber (A4) has a composition of 49.3% by weight of ethyl acrylate unit and 49.3 of n-butyl acrylate unit. %, And mono-n-butyl fumarate unit was 1.4% by weight. Regarding the acrylic rubber (A4), the residual amounts of the anionic emulsifier, the nonionic emulsifier, the coagulant, the antiaging agent, and the lubricant in the acrylic rubber (A4) were measured according to the above method. The results are shown in Table 1.

[Example 1]
Using a Banbury mixer, 100 parts of the acrylic rubber (A1) obtained in Production Example 1, 30 parts of clay (trade name "Satinton clay 5A", manufactured by Takehara Chemical Industry Co., Ltd., calcined kaolin), silica (trade name " Carplex 1120 ", manufactured by Evonik 15 parts, silica (trade name" Carplex 67 ", manufactured by Evonik) 35 parts, stearic acid 2 parts, ester wax (trade name" GREC G-8205 ", Dainippon Ink) Chemical Co., Ltd.) 1 part, 4,4′-bis (α, α-dimethylbenzyl) diphenylamine (trade name “Nocrac CD”, Ouchi Shinko Chemical Co., Ltd.) 2 parts, and 3-methacryloxypropyltrimethoxy 1 part of silane (trade name "KBM-503", manufactured by Shin-Etsu Silicone Co., Ltd., silane coupling agent) was added and mixed at 50 ° C for 5 minutes. Then, the obtained mixture was transferred to a roll at 50 ° C., 0.6 parts of hexamethylenediamine carbamate (trade name “Diak # 1”, an aliphatic polyamine compound manufactured by DuPont Dow Elastomer Co., Ltd.), and 1,3 Two parts of -di-o-tolylguanidine (trade name "NOXCELLER DT", a cross-linking accelerator manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) were mixed and kneaded to obtain an acrylic rubber composition.

  Then, using the obtained acrylic rubber composition, each of the tensile strength, elongation, compression set, and water resistance was measured and evaluated according to the above method. The results are shown in Table 1.

[Example 2]
An acrylic rubber composition was obtained in the same manner as in Example 1 except that the acrylic rubber (A2) obtained in Production Example 2 was used instead of the acrylic rubber (A1) obtained in Production Example 1. Table 1 shows the results of similar measurement and evaluation.

[Example 3]
An acrylic rubber composition was obtained in the same manner as in Example 1 except that the acrylic rubber (A3) obtained in Production Example 3 was used in place of the acrylic rubber (A1) obtained in Production Example 1. Table 1 shows the results of similar measurement and evaluation.

[Comparative Example 1]
An acrylic rubber composition was obtained in the same manner as in Example 1 except that the acrylic rubber (A4) obtained in Production Example 4 was used in place of the acrylic rubber (A1) obtained in Production Example 1. Table 1 shows the results of similar measurement and evaluation.

（＊１）単量体乳化液作製のための配合剤の添加量は、仕込み単量体１００部に対する配合量で示した。
（＊２）凝固前の乳化重合液に添加した配合剤の添加量は、乳化重合液１００部に対する配合量で示した。
（＊３）凝固工程で使用した凝固剤の添加量は、乳化重合液に、老化防止剤、ポリエチレンオキシド、および滑剤を添加することにより得られた混合液１００部に対する配合量で示した。

(* 1) The addition amount of the compounding agent for preparing the monomer emulsion is indicated by the compounding amount based on 100 parts of the charged monomer.
(* 2) The amount of the compounding agent added to the emulsion polymerization liquid before coagulation was shown as the amount to be mixed with 100 parts of the emulsion polymerization liquid.
(* 3) The addition amount of the coagulant used in the coagulation step is shown as the amount to be mixed with 100 parts of the mixed liquid obtained by adding the antioxidant, the polyethylene oxide, and the lubricant to the emulsion polymerization liquid.

[Evaluation of Examples 1 to 3 and Comparative Example 1]
As shown in Table 1, the cross-linked rubber obtained by using the acrylic rubber in which the residual amount (content) of the anionic emulsifier is 10 weight ppm or more and 4,500 weight ppm or less has a tensile strength of all. It was high and was excellent in compression set resistance and water resistance (Examples 1 to 3).
On the other hand, the rubber cross-linked product obtained by using the acrylic rubber having the residual amount (content) of the anionic emulsifier exceeding 4,500 ppm by weight was inferior in water resistance (Comparative Example 1).

[Production Example 5]
In a mixing container equipped with a homomixer, 46.294 parts of pure water, 50 parts of ethyl acrylate, 35 parts of n-butyl acrylate, 12.9 parts of 2-methoxyethyl acrylate, 2.1 parts of chlorovinyl acetate, anion. 0.421 parts of sodium lauryl sulphate (trade name "Emar 2FG", manufactured by Kao Corporation) as a hydrophilic emulsifier, and polyoxyethylene dodecyl ether (trade name "Emulgen 105" as a nonionic surfactant, weight average molecular weight: about 1.4 parts (1500, manufactured by Kao Co.) were charged and stirred to obtain a monomer emulsion.

  Then, 170.853 parts of pure water and 2.96 parts of the monomer emulsion obtained above were put into a polymerization reaction tank equipped with a thermometer and a stirrer, and the temperature was 12 ° C. under a nitrogen stream. Cooled down. Then, in a polymerization reaction tank, 145.16 parts of the monomer emulsion obtained above, 0.00033 part of ferrous sulfate as a reducing agent, 0.264 part of sodium ascorbate as a reducing agent, and Then, 7.72 parts of a 2.85 wt% potassium persulfate aqueous solution (0.22 parts as the amount of potassium persulfate) as a polymerization initiator was continuously added dropwise over 3 hours. Then, while maintaining the temperature in the polymerization reaction tank at 23 ° C., the reaction was continued for 1 hour, and it was confirmed that the polymerization conversion rate reached 95%. Polymerization was performed by adding hydroquinone as a polymerization terminator. The reaction was stopped and an emulsion polymerization liquid was obtained.

  Then, with respect to 100 parts of the emulsion polymerization liquid obtained by the polymerization, stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate as an antiaging agent (trade name "Irganox 1076", BASF (Manufactured by the same company) 0.3 part (total of charged monomers used when manufacturing emulsion polymerization liquid (that is, total of ethyl acrylate, n-butyl acrylate, 2-methoxyethyl acrylate, vinyl chloroacetate) ) 1 part to 100 parts) and polyethylene oxide (weight average molecular weight (Mw) = 100,000) 0.011 part (to 100 parts in total of the charged monomers used in the production of the emulsion polymerization solution). 0.036 parts) to obtain a mixed solution. Then, the obtained mixed solution was transferred to a coagulation tank, 60 parts of industrial water was added to 100 parts of this mixed solution, the temperature was raised to 85 ° C., and then the mixed solution was stirred at a temperature of 85 ° C. However, 3.3 parts of sodium sulfate as a coagulant (11 parts with respect to 100 parts of the polymer contained in the mixed solution) was continuously added to solidify the polymer, whereby the acrylic rubber (A5) To obtain a hydrous crumb.

  Then, to 100 parts of the solid content of the hydrous crumb obtained above, 388 parts of industrial water was added, and the mixture was stirred at room temperature for 5 minutes in the coagulation tank, and then water was discharged from the coagulation tank. The hydrous crumb was washed with water. In this production example, such washing with water was repeated 4 times. Then, the water-containing crumb that had been washed with water was dried at 110 ° C. for 1 hour with a hot air dryer to obtain a solid acrylic rubber (A5).

  The acrylic rubber (A5) thus obtained has a Mooney viscosity (ML1 + 4, 100 ° C.) of 38, and the composition of the acrylic rubber (A5) is as follows: ethyl acrylate unit: 50% by weight, n-butyl acrylate unit: 35% by weight, acrylic: The amount of 2-methoxyethyl acid unit was 12.9% by weight, and the amount of vinyl chloroacetate unit was 2.1% by weight. Regarding the acrylic rubber (A5), the residual amounts of the anionic emulsifier, the nonionic emulsifier, the coagulant, and the antiaging agent in the acrylic rubber (A5) were measured according to the above method. The results are shown in Table 2.

[Production Example 6]
A monomer emulsion was obtained in the same manner as in Production Example 5, except that the amount of sodium lauryl sulfate used as an anionic emulsifier was changed from 0.421 parts to 0.567 parts. Then, a solid acrylic rubber (A6) was obtained in the same manner as in Production Example 5 except that the obtained monomer emulsion was used.

  The obtained acrylic rubber (A6) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 38, and the composition of the acrylic rubber (A6) is as follows: ethyl acrylate unit 50 wt%, n-butyl acrylate unit 35 wt%, acrylic The amount of 2-methoxyethyl acid unit was 12.9% by weight, and the amount of vinyl chloroacetate unit was 2.1% by weight. Regarding the acrylic rubber (A6), the residual amounts of the anionic emulsifier, the nonionic emulsifier, the coagulant, and the antiaging agent in the acrylic rubber (A6) were measured according to the above method. The results are shown in Table 2.

[Production Example 7]
In the same manner as in Production Example 5, except that the amount of sodium lauryl sulfate used as an anionic emulsifier was changed from 0.421 parts to 0.283 parts and the number of washings with water was changed from 4 times to 8 times, A body emulsion was obtained. Then, a solid acrylic rubber (A7) was obtained in the same manner as in Production Example 5 except that the obtained monomer emulsion was used.

  The resulting acrylic rubber (A7) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 38, and the composition of the acrylic rubber (A7) is as follows: ethyl acrylate unit: 50% by weight, n-butyl acrylate unit: 35% by weight, acrylic: The amount of 2-methoxyethyl acid unit was 12.9% by weight, and the amount of vinyl chloroacetate unit was 2.1% by weight. Regarding the acrylic rubber (A7), the residual amounts of the anionic emulsifier, the nonionic emulsifier, the coagulant, and the antiaging agent in the acrylic rubber (A7) were measured according to the above method. The results are shown in Table 2.

[Production Example 8]
A monomer emulsion was obtained in the same manner as in Production Example 5, except that the amount of sodium lauryl sulfate used as an anionic emulsifier was changed from 0.421 parts to 0.661 parts. Then, a solid acrylic rubber (A8) was obtained in the same manner as in Production Example 5 except that the obtained monomer emulsion was used.

  The resulting acrylic rubber (A8) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 38, and the composition of the acrylic rubber (A8) is as follows: ethyl acrylate unit 50 wt%, n-butyl acrylate unit 35 wt%, acrylic The amount of 2-methoxyethyl acid unit was 12.9% by weight, and the amount of vinyl chloroacetate unit was 2.1% by weight. Regarding the acrylic rubber (A8), the residual amounts of the anionic emulsifier, the nonionic emulsifier, the coagulant, and the antiaging agent in the acrylic rubber (A8) were measured according to the above method. The results are shown in Table 2.

[Production Example 9]
A monomer emulsion was obtained in the same manner as in Production Example 5, except that the amount of sodium lauryl sulfate used as an anionic emulsifier was changed from 0.421 parts to 0.704 parts. Then, a solid acrylic rubber (A9) was obtained in the same manner as in Production Example 5 except that the obtained monomer emulsion was used.

  The resulting acrylic rubber (A9) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 38, and the composition of the acrylic rubber (A9) is as follows: ethyl acrylate unit 50 wt%, n-butyl acrylate unit 35 wt%, acrylic The amount of 2-methoxyethyl acid unit was 12.9% by weight, and the amount of vinyl chloroacetate unit was 2.1% by weight. Regarding the acrylic rubber (A9), the residual amounts of the anionic emulsifier, the nonionic emulsifier, the coagulant, and the antiaging agent in the acrylic rubber (A9) were measured according to the above method. The results are shown in Table 2.

[Production Example 10]
A monomer emulsion was obtained in the same manner as in Production Example 5, except that the amount of sodium lauryl sulfate used as an anionic emulsifier was changed from 0.421 parts to 0.754 parts. Then, a solid acrylic rubber (A10) was obtained in the same manner as in Production Example 5 except that the obtained monomer emulsion was used.

  The obtained acrylic rubber (A10) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 38, and the composition of the acrylic rubber (A10) is as follows: ethyl acrylate unit 50% by weight, n-butyl acrylate unit 35% by weight, acrylic The amount of 2-methoxyethyl acid unit was 12.9% by weight, and the amount of vinyl chloroacetate unit was 2.1% by weight. Regarding the acrylic rubber (A10), the residual amounts of the anionic emulsifier, the nonionic emulsifier, the coagulant, and the antiaging agent in the acrylic rubber (A10) were measured according to the above method. The results are shown in Table 2.

[Production Example 11]
A monomer emulsion was obtained in the same manner as in Production Example 5, except that the amount of sodium lauryl sulfate used as an anionic emulsifier was changed from 0.421 parts to 0.788 parts. Then, a solid acrylic rubber (A11) was obtained in the same manner as in Production Example 5 except that the obtained monomer emulsion was used.

  The obtained acrylic rubber (A11) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 38, and the composition of the acrylic rubber (A11) is as follows: ethyl acrylate unit 50% by weight, n-butyl acrylate unit 35% by weight, acrylic The amount of 2-methoxyethyl acid unit was 12.9% by weight, and the amount of vinyl chloroacetate unit was 2.1% by weight. Regarding the acrylic rubber (A11), the residual amounts of the anionic emulsifier, the nonionic emulsifier, the coagulant, and the antiaging agent in the acrylic rubber (A11) were measured according to the above method. The results are shown in Table 2.

[Production Example 12]
A monomer emulsion was obtained in the same manner as in Production Example 5, except that the amount of sodium lauryl sulfate used as an anionic emulsifier was changed from 0.421 parts to 0.854 parts. Then, a solid acrylic rubber (A12) was obtained in the same manner as in Production Example 5 except that the obtained monomer emulsion was used.

  The obtained acrylic rubber (A12) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 38, and the composition of the acrylic rubber (A12) is as follows: ethyl acrylate unit 50 wt%, n-butyl acrylate unit 35 wt%, acrylic The amount of 2-methoxyethyl acid unit was 12.9% by weight, and the amount of vinyl chloroacetate unit was 2.1% by weight. Regarding the acrylic rubber (A12), the residual amounts of the anionic emulsifier, the nonionic emulsifier, the coagulant, and the antiaging agent in the acrylic rubber (A12) were measured according to the above method. The results are shown in Table 2.

[Example 4]
Using a Banbury mixer, 100 parts of the acrylic rubber (A5) obtained in Production Example 5 was added to 60 parts of FEF carbon black (trade name "Cast SO", manufactured by Tokai Carbon Co., Ltd.), 2 parts of stearic acid, and an ester wax ( Trade name "GREC G-8205", manufactured by Dainippon Ink and Chemicals, Inc. 1 part, and 4,4'-bis (α, α-dimethylbenzyl) diphenylamine (trade name "Nocrac CD", manufactured by Ouchi Shinko Chemical Industry Co., Ltd. ) 2 parts were added and mixed at 50 ° C. for 5 minutes. Then, the obtained mixture was transferred to a roll at 50 ° C., 0.3 part of sulfur (trade name “Salfax PMC”, manufactured by Tsurumi Chemical Industry Co., Ltd.), sodium stearate (trade name “NS Soap”, manufactured by Kao Corporation) , A cross-linking accelerator) and 0.5 part of potassium stearate (trade name "NONSAR SK-1", manufactured by NOF CORPORATION, a cross-linking accelerator), and kneaded to give an acrylic rubber composition. Obtained.

  Then, using the obtained acrylic rubber composition, each of the tensile strength, elongation, compression set, and water resistance was measured and evaluated according to the above method. The results are shown in Table 2.

[Example 5]
An acrylic rubber composition was obtained in the same manner as in Example 4 except that the acrylic rubber (A6) obtained in Production Example 6 was used instead of the acrylic rubber (A5) obtained in Production Example 5. Table 2 shows the results of similar measurement and evaluation.

[Example 6]
Using a Banbury mixer, 100 parts of the acrylic rubber (A6) obtained in Production Example 6 was mixed with 60 parts of FEF carbon black (trade name "Cast SO", manufactured by Tokai Carbon Co., Ltd.), 2 parts of stearic acid, and an ester wax ( Trade name "GREC G-8205", manufactured by Dainippon Ink and Chemicals, Inc. 1 part, and 4,4'-bis (α, α-dimethylbenzyl) diphenylamine (trade name "Nocrac CD", manufactured by Ouchi Shinko Chemical Industry Co., Ltd. ) 2 parts were added and mixed at 50 ° C. for 5 minutes. Then, the obtained mixture was transferred to a roll at 50 ° C., and 0.5 parts of 1,3,5-triazine-2,4,6-trithiol (trade name “ZISNET F”, manufactured by Sankyo Kasei Co., Ltd.), dibutyl were used. 1.5 parts of zinc dithiocarbamate (trade name "NOXCELLER BZ", Ouchi Shinko Chemical Industry Co., Ltd., crosslinking accelerator), diethyl thiourea (trade name "NOXCELLER EUR", Ouchi Shinko Chemical Industry Ltd., crosslinking accelerator) An acrylic rubber composition was prepared by mixing 0.3 part and 0.2 part of N- (cyclohexylthio) phthalimide (trade name “Retarder CTP, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., scorch inhibitor) and kneading. Got
Then, the obtained acrylic rubber composition was obtained and measured and evaluated in the same manner as in Example 4, and the results are shown in Table 2.

[Example 7]
An acrylic rubber composition was obtained in the same manner as in Example 4 except that the acrylic rubber (A5) obtained in Production Example 5 was replaced with the acrylic rubber (A7) obtained in Production Example 7. Table 2 shows the results of similar measurement and evaluation.

[Comparative Examples 2 to 6]
Instead of the acrylic rubber (A5) obtained in Production Example 5, the acrylic rubbers (A8) to (A12) obtained in Production Examples 8 to 12 were used, respectively, in the same manner as in Example 4, Table 2 shows the results obtained by obtaining the acrylic rubber composition and performing the same measurement and evaluation.

（＊４）単量体乳化液作製のための配合剤の添加量は、仕込み単量体１００部に対する配合量で示した。
（＊５）凝固前の乳化重合液に添加した配合剤の添加量は、乳化重合液１００部に対する配合量で示した。
（＊６）凝固工程で使用した凝固剤の添加量は、乳化重合液に、老化防止剤、およびポリエチレンオキシドを添加することにより得られた混合液１００部に対する配合量で示した。
（＊７）架橋剤の配合量は、アクリルゴム１００部に対する配合量で示した。

(* 4) The addition amount of the compounding agent for preparing the monomer emulsion is shown by the compounding amount based on 100 parts of the charged monomer.
(* 5) The amount of the compounding agent added to the emulsion polymerization liquid before coagulation was shown as the amount to be mixed with 100 parts of the emulsion polymerization liquid.
(* 6) The addition amount of the coagulant used in the coagulation step is shown as the amount to be mixed with 100 parts of the mixed liquid obtained by adding the antioxidant and the polyethylene oxide to the emulsion polymerization liquid.
(* 7) The compounding amount of the cross-linking agent is shown by the compounding amount based on 100 parts of the acrylic rubber.

[Evaluation of Examples 4 to 7 and Comparative Examples 2 to 6]
As shown in Table 2, the crosslinked rubber obtained by using the acrylic rubber having the residual amount (content) of the anionic emulsifier of 10 wtppm or more and 4,500 wtppm or less has a tensile strength of any. It was high and excellent in balance with compression set resistance and water resistance (Examples 4 to 7). In particular, when an acrylic rubber containing a monomer unit containing a chlorine atom was used as the acrylic rubber, by comparing Examples 4, 5 and 7 in which sulfur was used as the cross-linking agent, the residual anionic emulsifier was found. It can be confirmed that the elongation can be further increased by setting the amount to 500 ppm by weight or more. Further, by comparing Examples 4, 5 and 7 using sulfur as a crosslinking agent with Example 6 using a triazine compound as a crosslinking agent, it is possible to obtain tensile strength and elongation by using sulfur as a crosslinking agent. It can be confirmed that the compression set can be further improved, and that the compression set resistance can be further improved by using the triazine compound as the crosslinking agent.
On the other hand, the rubber cross-linked product obtained by using the acrylic rubber having the residual amount (content) of the anionic emulsifier of more than 4,500 ppm by weight has any of tensile strength, compression set resistance and water resistance. The result was inferior, and the tensile strength was particularly low (Comparative Examples 2 to 6).

Claims (15)

The content of anionic emulsifier, 10 wt ppm or more state, and are less 4,500 ppm by weight,
The content of the nonionic emulsifier is 10 ppm by weight or more and 20,000 ppm by weight or less,
Acrylic rubber having an antioxidant content of 500 ppm by weight or more . The acrylic rubber according to claim 1 , wherein the content of the nonionic emulsifier is 10 ppm by weight or more and 15,000 ppm by weight or less. Content of a coagulant is 10 weight ppm or more and 9,000 weight ppm or less, The acrylic rubber of Claim 1 or 2 . The acrylic rubber according to claim 3 , wherein the content of the coagulant is 10 ppm by weight or more and 3,500 ppm by weight or less. The content of lubricant, acrylic rubber according to any one of claims 1 to 4, 0.1 to 0.4 wt%. The acrylic rubber according to claim 5 , wherein the content of the lubricant is 0.2 to 0.3% by weight. Content of an antioxidant is 12,000 weight ppm or less, The acrylic rubber in any one of Claims 1-6 . Acrylic rubber according to any one of claims 1 to 7 the content of the acrylic rubber component is 95 wt% or more. The acrylic rubber, acrylic rubber according to any one of claims 1 to 8 containing units of a monomer having a halogen atom. A method for producing acrylic rubber according to any one of claims 1 to 9
In the presence of an anionic emulsifier and a nonionic emulsifier , by emulsion polymerization of the monomer for forming the acrylic rubber, an emulsion polymerization step to obtain an emulsion polymerization liquid,
In the emulsion polymerization liquid before performing coagulation, an addition step of containing the antioxidant,
A method for producing an acrylic rubber, comprising a coagulation step of obtaining a hydrous crumb by adding a coagulant to the emulsion polymerization liquid and coagulating the emulsion polymerization liquid. The method for producing an acrylic rubber according to claim 10 , wherein, in the adding step, the emulsion polymerization liquid further contains the lubricant in addition to the antioxidant . The method for producing an acrylic rubber according to claim 10 , wherein, in the addition step, the emulsion polymerization liquid further contains the lubricant and an ethylene oxide polymer in addition to the antioxidant . The method for producing an acrylic rubber according to claim 10 or 11 , wherein, in the adding step, the emulsion polymerization liquid further contains an ethylene oxide polymer in addition to the antioxidant . Acrylic rubber composition containing an acrylic rubber described, and a crosslinking agent in any of claims 1-8. A rubber cross-linked product obtained by cross-linking the acrylic rubber composition according to claim 14 .