JP6696583B2 - 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 to an acrylic rubber that gives a rubber crosslinked product having excellent compression set resistance and water resistance, and a rubber crosslinked product using this acrylic rubber.

  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 circumstances, and provides an acrylic rubber that gives a rubber crosslinked product excellent in compression set resistance and water resistance, and a rubber crosslinked product using the acrylic rubber. With the goal.

  The present inventors, as a result of intensive research to achieve the above object, found that the above object can be achieved by setting the amount of the coagulant remaining in the acrylic rubber within a specific amount range, and to complete the present invention. I arrived.

That is, according to the present invention, an acrylic rubber in which the residual amount of the coagulant is 10 weight ppm or more and 10,000 weight ppm or less is provided.
In the acrylic rubber of the present invention, the residual amount of the coagulant is preferably 10 weight ppm or more and 3,500 weight ppm or less, and more preferably 500 weight ppm or more and 3,500 weight ppm or less.
In the acrylic rubber of the present invention, the coagulant is preferably a metal salt having a valence of 1 to 3, and the coagulant is more preferably calcium chloride, sodium chloride, magnesium sulfate or sodium sulfate.
In the acrylic rubber of the present invention, the residual amount of the emulsifier is preferably 10 weight ppm or more and 22,000 weight ppm or less.
In the acrylic rubber of the present invention, the residual amount of the lubricant is preferably 0.1 to 0.4% by weight.
In the acrylic rubber of the present invention, the residual amount of the antioxidant is preferably 500 weight ppm or more and 12,000 weight ppm or less.
The acrylic rubber of the present invention preferably has an acrylic rubber component content of 95% by weight or more.

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 to obtain an emulsion-polymerized liquid, and the emulsion-polymerized liquid. In addition, a coagulation step of adding a coagulant to obtain a water-containing crumb, a washing step of washing the water-containing crumb, and a drying step of drying the washed water-containing crumb. A method of manufacturing the same is provided.
In the method for producing an acrylic rubber of the present invention, the addition amount of the coagulant is preferably 3 to 33 parts by weight with respect to 100 parts by weight of the acrylic rubber component contained in the emulsion polymerization liquid.
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 containing at least one selected from a lubricant, an antioxidant and an 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, an acrylic rubber that gives a crosslinked rubber excellent in compression set resistance and water resistance, and a rubber obtained by using such an acrylic rubber, which is excellent in compression set resistance and water resistance. A crosslinked product can be provided.

<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. ] A rubber-like polymer containing units, wherein the residual amount of the coagulant is 10 ppm by weight or more and 10,000 ppm by weight 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 used in the present invention may contain a crosslinkable monomer unit, if necessary, in addition to the α, β-ethylenically unsaturated carboxylic acid 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.

  The α, β-ethylenically unsaturated carboxylic acid monomer forming the α, β-ethylenically unsaturated carboxylic acid monomer unit is not particularly limited, but for example, α, β- having 3 to 12 carbon atoms. Ethylenically unsaturated monocarboxylic acid, α, β-ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms, and α, β-ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms and alkanol having 1 to 8 carbon atoms And monoesters with. 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, butenedionic acid mono-chain alkyl ester or butenedionic acid monoester having an alicyclic structure is preferable, and mono-n-butyl fumarate, mono-n-butyl maleate, monocyclohexyl fumarate, and monocyclohexyl maleate are preferable. More preferably, mono-n-butyl fumarate is even more 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 improve the compression set resistance while improving the oil resistance and heat resistance.

  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.

  In the acrylic rubber of the present invention, the residual amount of the coagulant is 10,000 ppm by weight or less, preferably 7,000 ppm by weight or less, more preferably 5,000 ppm by weight or less, and further preferably 3,500. Weight ppm or less, and the lower limit of the residual amount of the coagulant is 10 weight ppm or more. The acrylic rubber of the present invention is obtained by emulsion-polymerizing the above-mentioned monomer, but when coagulating the emulsion-polymerized liquid obtained by emulsion-polymerization, a coagulant is usually used. Become. Therefore, the acrylic rubber obtained by emulsion polymerization such as the acrylic rubber of the present invention inevitably contains a coagulant. On the other hand, according to the present invention, by making the residual amount of the coagulant in the acrylic rubber within the above range, the compression set resistance and water resistance in the case of a rubber crosslinked product are made excellent. Can be done. In the acrylic rubber of the present invention, it is preferable that the residual amount of the coagulant is small. Therefore, by reducing the amount of the coagulant used during coagulation, a method of reducing the residual amount of the coagulant in the acrylic rubber is also available. Although conceivable, the coagulation becomes insufficient, the recovery rate of the acrylic rubber is deteriorated, and it is necessary to wash a lot with water. Therefore, from the viewpoint of stable production, the residual amount of the coagulant in the acrylic rubber is preferably It is 200 ppm by weight or more, and more preferably 500 ppm by weight or more. 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. The method for setting the residual amount of the coagulant to the above-mentioned amount is not particularly limited, but in the method for producing an acrylic rubber described below, a method for appropriately selecting a preferred embodiment as a method for reducing the residual amount of the coagulant, and Examples include a method of appropriately combining such aspects.

  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, calcium chloride, sodium chloride, magnesium sulfate and sodium sulfate are more preferable, and magnesium sulfate and sodium sulfate are more preferable. Moreover, these can be used individually by 1 type or in combination of 2 or more types.

  Further, in the acrylic rubber of the present invention, the residual amount of the emulsifier contained in the acrylic rubber is 22,000 ppm by weight or less from the viewpoint that the water resistance can be further improved when the rubber crosslinked product is used. It is more preferably 20,000 ppm by weight or less, still more preferably 18,000 ppm by weight or less, and particularly preferably 17,000 ppm by weight or less. The lower limit of the residual amount of the emulsifier is not particularly limited, but is preferably 10 ppm by weight or more, more preferably 200 ppm by weight or more, and further preferably 500 ppm by weight or more. The acrylic rubber of the present invention is obtained by emulsion-polymerizing the above-mentioned monomer, but an emulsifier is usually used in the emulsion-polymerization. Therefore, the acrylic rubber obtained by emulsion polymerization such as the acrylic rubber of the present invention inevitably contains an emulsifier. On the other hand, according to the present invention, by setting the residual amount of the emulsifier in the acrylic rubber within the above range, the water resistance of the rubber crosslinked product can be further enhanced. The residual amount of the emulsifier can be determined, for example, from the peak area of the molecular weight corresponding to the emulsifier in the measurement chart obtained by GPC measurement of acrylic rubber. The method for adjusting the residual amount of the emulsifier to the above-mentioned amount is not particularly limited, and for example, as will be described later, the emulsifier is used in combination with a nonionic emulsifier and an anionic emulsifier, and its addition amount is described below. A method of setting the range is included.

  Further, the acrylic rubber of the present invention contains a coagulant 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, more preferably Is 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,
By emulsion polymerization of a monomer for forming an acrylic rubber, an emulsion polymerization step of obtaining 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,
A method for producing an acrylic rubber, comprising:

<Emulsion polymerization step>
The emulsion polymerization step in the above production method is a step of emulsion-polymerizing a monomer for forming an acrylic rubber to obtain an emulsion polymerization liquid.

  As the emulsion polymerization method in the emulsion polymerization step, a usual method may be used, and an emulsifier, a polymerization initiator, a polymerization terminator and the like can be used according to a conventional method.

  The emulsifier is not particularly limited, and examples thereof include polyoxyethylene alkyl ether such as polyoxyethylene dodecyl ether, polyoxyethylene alkylphenol ether such as polyoxyethylene nonylphenyl ether, and polyoxyethylene alkyl ester such as polyoxyethylene stearic acid ester. Nonionic emulsifiers such as esters, polyoxyethylene sorbitan alkyl esters and polyoxyethylene polyoxypropylene copolymers; salts of fatty acids such as myristic acid, palmitic acid, oleic acid and linolenic acid; alkylbenzene sulfone such as sodium dodecylbenzenesulfonate. Acid salts, higher alcohol sulfate salts such as sodium lauryl sulfate, higher phosphate salts such as sodium alkyl phosphate, anionic emulsifiers such as alkyl sulfosuccinates; alkyl trimethyl ammonium chloride, dialkyl ammonium chloride, benzyl ammonium chloride, etc. And a cationic emulsifier; These emulsifiers can be used alone or in combination of two or more kinds. 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. Among these anionic emulsifiers, higher phosphate ester salts and higher alcohol sulfate ester salts are preferable.

  Among these emulsifiers, nonionic emulsifiers and anionic emulsifiers are preferable, and nonionic emulsifiers and anionic emulsifiers are preferably used in combination. By using a combination of a nonionic emulsifier and an anionic emulsifier, it is used in the coagulation step to be described later while effectively suppressing 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. It is possible to reduce the amount of the coagulant used, and as a result, it is possible to reduce the amount of the coagulant in the finally obtained acrylic rubber.

  Further, by using a combination of a nonionic emulsifier and an anionic emulsifier, the emulsifying action can be enhanced, so that the amount of the emulsifier itself used can be reduced, and as a result, the acrylic rubber finally obtained The residual amount of the emulsifier contained in can be reduced, and thus the water resistance of the resulting acrylic rubber can be further enhanced.

  In the above-mentioned production method, the amount of the emulsifier to be used is the total amount of the emulsifier to be used, preferably 0.1 to 5 parts by weight, more preferably 0.5 to 4 parts by weight, based on 100 parts by weight of the monomer used for the polymerization. It is preferably 1 to 3 parts by weight. When the nonionic emulsifier and the anionic emulsifier are used in combination, the amount of the nonionic emulsifier used is more than 0 parts by weight, preferably 4 parts by weight, and more preferably 0. 1 to 3 parts by weight, more preferably 0.5 to 2 parts by weight, further preferably 0.7 to 1.7 parts by weight, and the amount of the anionic emulsifier used is 100 parts by weight of the monomer used for the polymerization. On the other hand, it is more than 0 parts by weight, 4 parts by weight, preferably 0.1 to 3 parts by weight, more preferably 0.5 to 2 parts by weight, still more preferably 0.35 to 0.75 parts by weight. When used in combination with a nonionic emulsifier and an anionic emulsifier, the weight ratio of the nonionic emulsifier / anionic emulsifier is preferably 1/99 to 99/1, and preferably 10/90 to 80/20. More preferably, 25/75 to 75/25 are even more preferable, 50/50 to 75/25 are even more preferable, and 65/35 to 75/25 are particularly preferable.

  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 initiation 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.

  Further, when carrying out the polymerization reaction while continuously dropping the monomer used for the polymerization, the monomer used for the polymerization is mixed with an emulsifier and water to prepare a monomer emulsion, It is preferable that the emulsion is continuously added dropwise. The method for preparing the monomer emulsion is not particularly limited, and a method in which the total amount of the monomers used in the polymerization, the total amount of the emulsifier, and water are stirred using a stirrer such as a homomixer or a disk turbine can be used. Can be mentioned. 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 for example, the above-mentioned monovalent to trivalent metal salts can be preferably used. The amount of the coagulant used is preferably 1 to 100 with respect to 100 parts by weight of the acrylic rubber component in the emulsion polymerization liquid, from the viewpoint that the residual amount of the coagulant in the finally obtained acrylic rubber is within the above range. Parts by weight, more preferably 2 to 40 parts by weight, further preferably 3 to 20 parts by weight, and particularly preferably 3 to 12 parts by weight. If the amount of the coagulant is too small, the coagulation will be insufficient and the yield of the acrylic rubber will be deteriorated. On the other hand, if it is too large, the residual amount of the coagulant in the finally obtained acrylic rubber will be too large. , The water resistance will deteriorate.

  The solidification temperature is not particularly limited, but is preferably 50 to 90 ° C, more preferably 60 to 80 ° 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 blended 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.

  In particular, by pre-blending the anti-aging agent in the emulsion polymerization liquid before coagulation, it is possible to effectively suppress the deterioration of the acrylic rubber due to heat during drying in the drying step described later. 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, by adding the antioxidant, it is possible to appropriately disperse the antioxidant, so even if the amount of the antioxidant is reduced, its addition effect is sufficient. It is something that can be demonstrated. 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. Even when the anti-aging agent is pre-blended in the emulsion polymerization liquid before coagulation, the pre-blended anti-aging agent is not substantially removed in the subsequent coagulation, washing, and drying. Therefore, even when preliminarily blended in the emulsion polymerization liquid, the effect of addition can be sufficiently exhibited.

  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 thiobisphenol 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 blending the lubricant in the emulsion polymerization liquid before solidification, the tack of the finally obtained acrylic rubber can be lowered, and it can be mixed with various compounding agents by using a mixing device such as a roll. In doing so, adhesion to a mixing device such as a roll can be suitably suppressed, and thereby productivity can be improved. That is, using a mixing device such as a roll, a method of adding a lubricant when blending various compounding agents into the acrylic rubber is conceivable, but in this method, the lubricant is dispersed in the initial stage of mixing by the roll. Since it is insufficient, sticking to the roll will occur, and as a result, the mixing time by the roll will be long, while pre-blending the lubricant in the emulsion polymerization liquid before solidification, Since the adhesion to the roll can be appropriately prevented from the initial stage of mixing by the roll, the mixing time by the roll can be shortened, and as a result, the productivity can be improved. In addition, since the lubricant can be appropriately dispersed by adding the lubricant in the state of the emulsion polymerization liquid, even when the amount of the lubricant is reduced, the effect of addition can be sufficiently exhibited. It is a thing. Specifically, the compounding amount of the lubricant is relatively small, preferably 0.1 to 2 parts by weight, more preferably 0.2 to 1 part by weight, based on 100 parts by weight of the acrylic rubber component in the emulsion polymerization liquid. The compounding amount can sufficiently exert the effect of addition. Even when the lubricant is pre-blended in the emulsion polymerization liquid before coagulation, the pre-blended lubricant is not substantially removed by subsequent coagulation, washing, drying, etc. Even when pre-blended in the liquid, the effect of the addition can be sufficiently exhibited.

  The lubricant is not particularly limited, and examples thereof include polyglycerin fatty acid ester, phosphoric acid ester, fatty acid ester, fatty acid amide, and higher fatty acid.

  Furthermore, by preliminarily blending the ethylene oxide polymer in the emulsion polymerization liquid before coagulation, the coagulability of the emulsion polymerization liquid can be improved, and thereby the amount of the coagulant in the coagulation step can be reduced. As a result, the residual amount in the finally obtained acrylic rubber can be reduced, and the compression set resistance and water resistance of the rubber crosslinked product can be further enhanced. 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 0.1 to 0.5 part by weight, based on 100 parts by weight of the acrylic rubber component in the emulsion polymerization liquid. The weight average molecular weight of the ethylene oxide polymer is 10,000 to 1,000,000, preferably 10,000 to 200,000, and more preferably 20,000 to 120,000.

  The order of adding the antioxidant, the lubricant and the ethylene oxide polymer to the emulsion polymerization liquid before solidification is not particularly limited and may be appropriately selected.

  Then, even when these antioxidants, lubricants and / or ethylene oxide polymers are preliminarily mixed in the emulsion polymerization liquid before coagulation, the coagulant is added to the emulsion polymerization liquid under the same conditions as above. A hydrous crumb can be obtained by carrying out a coagulation operation by using.

<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.

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

  The number of times of washing with water is not particularly limited, and may be once, but is preferably 2 to 10 times, more preferably 3 to 8 from the viewpoint of reducing the residual amount of the coagulant in the finally obtained acrylic rubber. Times. From the viewpoint of reducing the residual amount of the coagulant in the finally obtained acrylic rubber, it is desirable that the number of times of washing with water is large, but even if the washing is performed beyond the above range, the effect of removing the coagulant is still high. On the other hand, although the number of steps is small, the number of steps is increased, and the decrease in productivity is greatly affected.

  Moreover, in the present invention, 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 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.

  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 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.

  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 has excellent compression set resistance and water resistance while maintaining basic properties as a rubber such as tensile strength, elongation and hardness. Therefore, the rubber cross-linked product of the present invention takes advantage of such characteristics, for example, in a wide range of fields such as transportation machines such as automobiles, general equipment, and electric equipment, and seals such as O-rings, packings, oil seals, and bearing seals. It is preferably used as a material; a gasket; a cushioning material, a vibration damping material; an electric wire coating material; industrial belts; tubes and hoses; sheets;

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 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 emulsifier, anti-aging agent, and lubricant]
The residual amount of the emulsifier, the antioxidant and the lubricant 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 emulsifier, the antioxidant, and the lubricant used in the production were obtained, and these integrated values and the peaks of the acrylic rubber were integrated. The residual amounts of the emulsifier, the anti-aging agent and the lubricant were calculated by comparing the obtained values with the molecular weights corresponding to these integrated values.

[Recovery rate of acrylic rubber]
Calculate the ratio of the weight of the solid acrylic rubber after coagulation and drying to the weight of the acrylic rubber in the emulsion polymerization liquid calculated from the weight of the monomer used for polymerization (charged amount) and its polymerization conversion rate. Was defined as the recovery rate of acrylic rubber.

[Normal physical properties]
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, using this test piece, tensile strength and elongation were measured according to JIS K6251.

[Heat aging test]
A test piece prepared in the same manner as the test piece used for the evaluation of the above-mentioned normal physical properties was placed in an environment of a temperature of 175 ° C. for 504 hours in a gear type oven, and then the tensile strength and the elongation were measured and obtained. The heat aging resistance was evaluated by comparing the results with the normal physical properties measured according to the above method. The tensile strength and elongation were measured according to JIS K6251.
Regarding the tensile strength, the larger the measured value of the sample after heating, the better the heat resistance. Regarding the elongation, when the rate of change in elongation (percentage), which is the rate of change of the measured value of the sample after heating with respect to the measured value of the sample that has not been heat-aged (measured value of normal physical properties), is closer to 0, the heat resistance is better.

[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, anionic surfactant. 0.709 parts of sodium lauryl sulphate (trade name "Emar 2FG", manufactured by Kao) and polyoxyethylene dodecyl ether (trade name "Emulgen 105", weight average molecular weight: about 1500) as a nonionic surfactant. 1.82 parts (manufactured by Kao Corporation) were charged and stirred to obtain a monomer emulsion.

  Then, 170.853 parts of pure water and 2.98 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, 145.85 parts of the monomer emulsion obtained above, 0.00033 parts of ferrous sulfate as a reducing agent, 0.264 parts 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 (0.039 parts 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 100 parts in total 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.

  Next, to 100 parts of the solid content of the hydrous crumb obtained above, 194 parts of industrial water was added, and the mixture was stirred at 15 ° C. 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, to 100 parts of the solid content of the water-containing crumb washed with water as described above, an aqueous sulfuric acid solution (pH = 3) prepared by mixing 194 parts of industrial water and 0.13 part of concentrated sulfuric acid was added, and the mixture was placed in a coagulation tank. After stirring at 15.degree. C. for 5 minutes, water was discharged from the coagulation tank to pickle 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, 194 parts of pure water was added to 100 parts of the solid content of the hydrous crumb that had been pickled, and the mixture was stirred at 15 ° C. for 5 minutes in the coagulation tank, and then water was discharged from the coagulation tank to obtain the water content. The crumbs were washed with pure water, and the water-containing crumbs washed with pure water were dried with a hot air dryer at 110 ° C. for 1 hour to obtain a solid acrylic rubber (A1).

  The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A1) was 31, the recovery rate of the acrylic rubber (A1) was 100%, and the composition of the acrylic rubber (A1) was ethyl acrylate unit 49.3. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. Regarding the acrylic rubber (A1), the residual amounts of the coagulant, the surfactant, the lubricant, and the antiaging agent 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 surfactant was changed from 0.709 part to 0.624 part, and the amount of polyoxyethylene dodecyl ether used as a nonionic surfactant was changed from 1.82 part to 1.5 part. A monomer emulsion was obtained in the same manner as in Production Example 1 except that the above were changed. 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 33, the recovery rate of the acrylic rubber (A2) was 100%, and the composition of the acrylic rubber (A2) was ethyl acrylate unit 49.3. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. Regarding the acrylic rubber (A2), the residual amounts of the coagulant, the surfactant, the lubricant and the antioxidant 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 the anionic surfactant was changed from 0.709 parts to 0.567 parts, and the amount of polyoxyethylene dodecyl ether used as the nonionic surfactant was changed from 1.82 parts to 1.4 parts. A monomer emulsion was obtained in the same manner as in Production Example 1 except that the above were changed. 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 obtained acrylic rubber (A3) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 34, a recovery rate of the acrylic rubber (A3) is 100%, and the composition of the acrylic rubber (A3) is 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. Regarding the acrylic rubber (A3), the residual amounts of the coagulant, the surfactant, the lubricant, and the antioxidant 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 the anionic surfactant was changed from 0.709 parts to 0.567 parts, and the amount of polyoxyethylene dodecyl ether used as the nonionic surfactant was changed from 1.82 parts to 1.4 parts. A monomer emulsion was obtained in the same manner as in Production Example 1 except that the above were changed.

  Then, 179 parts of pure water and 2.98 parts of the monomer emulsion obtained above were put into a polymerization reaction tank equipped with a thermometer and a stirrer, and cooled to a temperature of 12 ° C. under a nitrogen stream. Then, 0.00033 parts of ferrous sulfate as a reducing agent, 0.264 parts of sodium formaldehyde sulfonate as a reducing agent, and 0.22 parts of potassium persulfate as a polymerization initiator were put into a polymerization reaction vessel at once. Then, 145.29 parts of the monomer emulsion obtained above was continuously added dropwise to the polymerization reaction tank over 3 hours, and then the temperature in the polymerization reaction tank was kept at 23 ° C. Then, the reaction was continued for 1 hour, and it was confirmed that the polymerization conversion rate reached 90%, and hydroquinone as a polymerization terminator was added to stop the polymerization reaction to obtain an emulsion polymerization liquid.

  Then, to the emulsion polymerization liquid obtained above, an antioxidant and a lubricant are added and mixed in the same manner as in Production Example 1 to obtain a mixed liquid, and the same is applied to the obtained mixed liquid. By carrying out the coagulation operation in the following manner, a water-containing crumb of the acrylic rubber (A4) is obtained, and the obtained water-containing crumb is similarly washed with water four times, pickled, washed with pure water and dried, A solid acrylic rubber (A4) was obtained.

  The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A4) was 31, the recovery rate of the acrylic rubber (A4) was 100%, and the composition of the acrylic rubber (A4) was 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. Further, the residual amounts of the coagulant, the surfactant, the lubricant and the antiaging agent in the acrylic rubber (A4) were measured according to the above method. The results are shown in Table 1.

[Production Example 5]
An emulsion polymerization liquid was obtained in the same manner as in Production Example 1, except that the monomer emulsion obtained in the same manner as in Production Example 3 was used. Then, in the same manner as in Production Example 1, an antioxidant and a lubricant are added to the obtained emulsion polymerization liquid and mixed to obtain a mixed liquid, and the obtained mixed liquid is coagulated in the same manner. By performing the operation, a water-containing crumb of acrylic rubber (A5) was obtained.

  Then, washing with water, pickling, washing with pure water and drying were carried out in the same manner as in Production Example 1 except that the number of washing with water was changed from 4 to 2 to obtain a solid acrylic rubber (A5). It was The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A5) was 33, the recovery rate of the acrylic rubber (A5) was 100%, and the composition of the acrylic rubber (A5) was 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit 49.3% by weight, mono-n-butyl fumarate unit 1.4% by weight. In addition, the residual amounts of the coagulant, surfactant, lubricant, and anti-aging agent in the acrylic rubber (A5) were measured according to the above method. The results are shown in Table 1.

[Production Example 6]
An emulsion polymerization liquid was obtained in the same manner as in Production Example 1, except that the monomer emulsion obtained in the same manner as in Production Example 3 was used. Then, in the same manner as in Production Example 1, an antioxidant and a lubricant are added to the obtained emulsion polymerization liquid and mixed to obtain a mixed liquid, and the obtained mixed liquid is coagulated in the same manner. By performing the operation, a water-containing crumb of acrylic rubber (A6) was obtained.

  Then, washing with water, pickling, washing with pure water and drying were carried out in the same manner as in Production Example 1 except that the number of washings with water was changed from 4 to 1 to obtain a solid acrylic rubber (A6). It was The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A6) was 32, the recovery rate of the acrylic rubber (A6) was 100%, and the composition of the acrylic rubber (A6) was 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. Further, the residual amounts of the coagulant, surfactant, lubricant, and anti-aging agent in the acrylic rubber (A6) were measured according to the above method. The results are shown in Table 1.

[Production Example 7]
As a coagulant used when performing the coagulation operation, a water-containing crumb of acrylic rubber (A7) was prepared in the same manner as in Production Example 3 except that 3.3 parts of magnesium sulfate was used instead of 3.3 parts of sodium sulfate. Obtained. Then, the obtained water-containing crumb was washed with water four times, pickled, washed with pure water and dried in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A7).

  The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A7) was 33, the recovery rate of the acrylic rubber (A7) was 100%, and the composition of the acrylic rubber (A7) was ethyl acrylate unit 49.3. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. Further, the residual amounts of the coagulant, the surfactant, the lubricant, and the antiaging agent in the acrylic rubber (A7) were measured according to the above method. The results are shown in Table 1.

[Production Example 8]
As a coagulant used when performing a coagulation operation, a water-containing crumb of acrylic rubber (A8) was prepared in the same manner as in Production Example 3 except that 3.3 parts of calcium chloride was used instead of 3.3 parts of sodium sulfate. Obtained. Then, the obtained water-containing crumb was washed with water four times, pickled, washed with pure water and dried in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A8).

  The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A8) was 35, the recovery rate of the acrylic rubber (A8) was 100%, and the composition of the acrylic rubber (A8) was 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. Further, the residual amounts of the coagulant, the surfactant, the lubricant and the antiaging agent in the acrylic rubber (A8) were measured according to the above method. The results are shown in Table 1.

[Production Example 9]
As an antiaging agent to be added to 100 parts by weight of the emulsion polymerization liquid obtained by the polymerization, instead of 0.3 part of stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,4-Bis [(octylthio) methyl] -6-methylphenol (trade name "Irganox 1520L", manufactured by BASF) 0.3 part (total of charged monomers used when producing an emulsion polymerization solution) A water-containing crumb of acrylic rubber (A9) was obtained in the same manner as in Production Example 3 except that 1 part per 100 parts) was used.

  Then, the obtained water-containing crumb was washed with water four times, pickled, washed with pure water and dried in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A9). The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A9) was 34, the recovery rate of the acrylic rubber (A9) was 100%, and the composition of the acrylic rubber (A9) was ethyl acrylate unit 49.3. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. Further, the residual amounts of the coagulant, the surfactant, the lubricant and the antiaging agent in the acrylic rubber (A9) were measured according to the above method. The results are shown in Table 1.

[Production Example 10]
As an antiaging agent to be added to 100 parts by weight of the emulsion polymerization liquid obtained by the polymerization, instead of 0.3 part of stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2-mercaptobenzimidazole (trade name "Nocrac MB", manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.) 0.3 part (1 part to 100 parts of the total amount of charged monomers used in the production of the emulsion polymerization solution) A water-containing crumb of acrylic rubber (A10) was obtained in the same manner as in Production Example 3 except that (1) was used.

  Then, the obtained water-containing crumb was washed with water four times, pickled, washed with pure water and dried in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A10). The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A10) was 33, the recovery rate of the acrylic rubber (A10) was 100%, and the composition of the acrylic rubber (A10) was ethyl acrylate unit 49.3. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. Further, the residual amounts of the coagulant, the surfactant, the lubricant, and the antiaging agent in the acrylic rubber (A10) were measured according to the above method. The results are shown in Table 1.

[Production Example 11]
As an antiaging agent to be added to 100 parts by weight of the emulsion polymerization liquid obtained by the polymerization, instead of 0.3 part of stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 4,4′-bis (α, α-dimethylbenzyl) diphenylamine (trade name “Nocrac CD”, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.) 0.3 part (single amount of preparation used when producing an emulsion polymerization solution) A water-containing crumb of acrylic rubber (A11) was obtained in the same manner as in Production Example 3 except that 1 part was used for 100 parts in total of the body.

  Then, the obtained water-containing crumb was washed with water four times, pickled, washed with pure water and dried in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A11). The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A11) was 32, the recovery rate of the acrylic rubber (A11) was 100%, and the composition of the acrylic rubber (A11) was ethyl acrylate unit 49.3. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. Further, the residual amounts of the coagulant, the surfactant, the lubricant, and the antiaging agent in the acrylic rubber (A11) were measured according to the above method. The results are shown in Table 1.

[Production Example 12]
As an antiaging agent to be added to 100 parts by weight of the emulsion polymerization liquid obtained by the polymerization, instead of 0.3 part of stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, Mono (or di or tri) (α-methylbenzyl) phenol (trade name “Nocrac SP”, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) 0.3 part (single amount of preparation used when manufacturing an emulsion polymerization solution) A water-containing crumb of acrylic rubber (A12) was obtained in the same manner as in Production Example 1 except that 1 part was used for 100 parts in total of the body.

  Then, the obtained water-containing crumb was washed with water four times, pickled, washed with pure water and dried in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A12). The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A12) was 31, the recovery rate of the acrylic rubber (A12) was 100%, and the composition of the acrylic rubber (A12) was ethyl acrylate unit 49.3. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. In addition, the residual amounts of the coagulant, the surfactant, the lubricant, and the antiaging agent in the acrylic rubber (A12) were measured according to the above method. The results are shown in Table 1.

[Production Example 13]
As a lubricant to be added to 100 parts by weight of the emulsion polymerization liquid obtained by the polymerization, a higher fatty acid (trade name "Moldwiz Int21G", manufactured by Tomoe Kogyo Co., Ltd.) 0 in place of 0.075 part of polyoxyethylene stearyl ether phosphoric acid Acrylic rubber (A13) in the same manner as in Production Example 1 except that 0.075 part (0.25 part based on 100 parts of the total amount of charged monomers used when producing the emulsion polymerization liquid) was used. To obtain a hydrous crumb.

  Then, the obtained water-containing crumb was washed with water four times, pickled, washed with pure water and dried in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A13). The obtained acrylic rubber (A13) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, a recovery rate of the acrylic rubber (A13) is 100%, and the composition of the acrylic rubber (A13) is ethyl acrylate unit 49.3. % By weight, n-butyl acrylate unit 49.3% by weight, mono-n-butyl fumarate unit 1.4% by weight. In addition, the residual amounts of the coagulant, surfactant, lubricant, and anti-aging agent in the acrylic rubber (A13) were measured according to the above method. The results are shown in Table 1.

[Production Example 14]
As a lubricant to be added to 100 parts by weight of the emulsion polymerization liquid obtained by the polymerization, a higher fatty acid (trade name "Moldwiz Int21G", manufactured by Tomoe Kogyo Co., Ltd.) 0 in place of 0.075 part of polyoxyethylene stearyl ether phosphoric acid 0.075 part (0.25 part per 100 parts of the total amount of charged monomers used when producing the emulsion polymerization liquid) was used, and sodium sulfate 3 was used as a coagulant used when performing a coagulation operation. A water-containing crumb of acrylic rubber (A13) was obtained in the same manner as in Production Example 12 except that 3.3 parts of sodium chloride was used instead of 0.3 part.

  Then, the obtained water-containing crumb was washed with water four times, pickled, washed with pure water and dried in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A14). The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A14) was 33, the recovery rate of the acrylic rubber (A14) was 100%, and the composition of the acrylic rubber (A14) was 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. In addition, the residual amounts of the coagulant, surfactant, lubricant, and antioxidant in the acrylic rubber (A14) were measured according to the above method. The results are shown in Table 1.

[Production Example 15]
Production Example except that the amount of sodium sulfate used as a coagulant used when performing the coagulation operation was changed from 3.3 parts to 0.3 part (1 part to 100 parts of the polymer contained in the mixed solution). In the same manner as in 13, a hydrous crumb of acrylic rubber (A15) was obtained. Next, the obtained water-containing crumb was washed with water four times, pickled, washed with pure water and dried in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A15).

  The obtained acrylic rubber (A15) had a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, a recovery rate of the acrylic rubber (A15) was 42%, and the composition of the acrylic rubber (A15) was 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. Further, the residual amounts of the coagulant, surfactant, lubricant, and anti-aging agent in the acrylic rubber (A15) were measured according to the above method. The results are shown in Table 1.

[Production Example 16]
Production Example except that the amount of sodium sulfate used as a coagulant used when performing the coagulation operation was changed from 3.3 parts to 0.6 parts (2 parts to 100 parts of the polymer contained in the mixed solution). A hydrous crumb of acrylic rubber (A16) was obtained in the same manner as in 13. Next, the obtained water-containing crumb was washed with water four times, pickled, washed with pure water and dried in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A16).

  The Mooney viscosity (ML1 + 4, 100 ° C.) of the obtained acrylic rubber (A16) was 33, the recovery rate of the acrylic rubber (A16) was 63%, and the composition of the acrylic rubber (A16) was 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. Further, the residual amounts of the coagulant, the surfactant, the lubricant, and the antiaging agent in the acrylic rubber (A16) were measured according to the above method. The results are shown in Table 1.

[Production Example 17]
Production Example except that the amount of sodium sulfate used as a coagulant used when performing the coagulation operation was changed from 3.3 parts to 10 parts (33.3 parts based on 100 parts of the polymer contained in the mixed solution). A hydrous crumb of acrylic rubber (A17) was obtained in the same manner as in 13. Then, the obtained water-containing crumb was washed with water four times, pickled, washed with pure water and dried in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A17).

  The obtained acrylic rubber (A17) had a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, a recovery rate of the acrylic rubber (A17) was 100%, and the composition of the acrylic rubber (A17) was 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit by 49.3% by weight, mono-n-butyl fumarate unit by 1.4% by weight. In addition, the residual amounts of the coagulant, surfactant, lubricant, and anti-aging agent in the acrylic rubber (A17) 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, according to the above-mentioned method, each measurement and evaluation of normal state physical properties, heat aging test, compression set, and water resistance were performed. The results are shown in Table 2.

[Examples 2 to 16]
In the same manner as in Example 1 except that the acrylic rubber (A1) obtained in Production Example 1 was replaced with the acrylic rubbers (A2) to (A16) obtained in Production Examples 2 to 16, respectively. Table 2 shows the results obtained by similarly obtaining and measuring the rubber composition.

[Comparative Example 1]
An acrylic rubber composition was obtained in the same manner as in Example 1, except that the acrylic rubber (A17) obtained in Production Example 17 was used instead of the acrylic rubber (A1) obtained in Production Example 1. Table 2 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.

As shown in Tables 1 and 2, all of the acrylic rubbers obtained in Production Examples 1 to 16 had a residual amount of the coagulant of 10 weight ppm or more and 10,000 weight ppm or less. The obtained rubber cross-linked products were all excellent in compression set resistance and water resistance (Examples 1 to 16). As can be seen from Table 1, the antioxidant and lubricant added to the emulsion polymerization liquid before coagulation were not substantially removed even after coagulation and drying, and the amount of the same amount as the compounded amount was used. Anti-aging agent and lubricant remained in the acrylic rubber.
On the other hand, in the acrylic rubber obtained in Production Example 17, the residual amount of the coagulant was more than 10,000 ppm by weight, and the rubber cross-linked product obtained using this resulted in poor water resistance (Comparative Example). 1).

Claims (10)

An acrylic rubber composition containing acrylic rubber,
In the acrylic rubber, a coagulant, an emulsifier and a lubricant are contained as residual components,
Residual amount of solidifying agent in the acrylic rubber is 10 ppm or greater state, and are less 3,500 ppm by weight,
The residual amount of the emulsifier in the acrylic rubber is 10 weight ppm or more and 17,000 weight ppm or less,
The coagulant contained as residual components in the acrylic rubber, calcium chloride, sodium chloride, magnesium sulfate or acrylic rubber composition is sodium sulfate. The acrylic rubber composition according to claim 1, wherein the residual amount of the coagulant in the acrylic rubber is 500 ppm by weight or more and 3,500 ppm by weight or less. The acrylic rubber composition according to claim 1 or 2 , wherein the residual amount of the lubricant in the acrylic rubber is 0.1 to 0.4% by weight. The acrylic rubber further contains an antioxidant as a residual component,
The remaining amount of antioxidant acrylic rubber is 500 ppm or greater, acrylic rubber composition according to any one of claims 1 to 3, 12,000 ppm by weight or less. Acrylic rubber composition according to any one of claims 1-4 content of acrylic rubber component in the acrylic rubber is 95 wt% or more. A method for producing acrylic rubber composition according to any one of claims 1 to 5
A monomer for forming an acrylic rubber, using an emulsifier, by emulsion polymerization, an emulsion polymerization step of obtaining an emulsion polymerization liquid,
In the emulsion polymerization liquid before performing coagulation, an addition step of containing a lubricant,
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,
A method for producing an acrylic rubber composition comprising: The method for producing an acrylic rubber composition according to claim 6 , wherein the amount of the coagulant added is 3 to 20 parts by weight with respect to 100 parts by weight of the acrylic rubber component contained in the emulsion polymerization liquid. The addition step, the polymer emulsion prior to the solidification, in addition to the lubricant, according to claim 6 or 7, which is a step of at least one selected from anti-aging agent and the ethylene oxide polymer A method for producing the acrylic rubber composition . Acrylic rubber composition according to any one of claims 1 to 5 crosslinkable acrylic rubber composition comprising a cross-linking agent. A rubber crosslinked product obtained by crosslinking the crosslinkable acrylic rubber composition according to claim 9 .