WO2018079783A1 - Acrylic rubber and crosslinked rubber - Google Patents

Abstract

Provided are: an acrylic rubber in which the residual amount of coagulant is 10-10,000 ppm by weight or more; and a crosslinked rubber using the acrylic rubber. According to the present invention, an acrylic rubber providing a crosslinked rubber having excellent compression set resistance and water resistance; and a crosslinked rubber using the acrylic rubber can be provided.

Description

Acrylic rubber and rubber cross-linked product

The present invention relates to an acrylic rubber and a rubber cross-linked product, and more particularly to an acrylic rubber that gives a rubber cross-linked product excellent in compression set resistance and water resistance, and a rubber cross-linked product using this acrylic rubber.

Acrylic rubber is a polymer mainly composed of an acrylate ester and is generally known as a rubber excellent in 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 polymerization of a monomer mixture constituting the acrylic rubber, coagulating the resulting emulsion polymerization solution by adding a coagulant, and drying the hydrous crumb obtained by coagulation. (See, for example, Patent Document 1).

On the other hand, in recent years, in automobile members such as seal materials, hose materials, vibration-proof materials, tube materials, belt materials or boot materials, in addition to heat resistance and oil resistance, compression set resistance and There is a demand for excellent water resistance. However, the conventional acrylic rubber such as the acrylic rubber described in Patent Document 1 does not necessarily have sufficient water resistance, and thus cannot meet the recent demand for water resistance.

JP 7-145291 A

The present invention has been made in view of such a situation, and provides an acrylic rubber which gives a rubber cross-linked product excellent in compression set resistance and water resistance, and a rubber cross-linked product using the acrylic rubber. With the goal.

As a result of intensive studies to achieve the above object, the present inventors have 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, thereby completing the present invention. It came.

That is, according to the present invention, there is provided an acrylic rubber having a residual amount of coagulant of 10 ppm by weight or more and 10,000 ppm by weight or less.
In the acrylic rubber of the present invention, the residual amount of the coagulant is preferably 10 ppm to 3,500 ppm, more preferably 500 ppm to 3,500 ppm.
In the acrylic rubber of the present invention, the coagulant is preferably a monovalent to trivalent metal salt, 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 ppm by weight or more and 22,000 ppm by weight 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 ppm by weight or more and 12,000 ppm by weight or less.
The acrylic rubber of the present invention preferably has an acrylic rubber component content of 95% by weight or more.

Further, according to the present invention, there is provided a method for producing the acrylic rubber, the emulsion polymerization step for obtaining an emulsion polymerization liquid by emulsion polymerization of a monomer for forming the acrylic rubber, and the emulsion polymerization liquid. An acrylic rubber comprising: a coagulating step of adding a coagulant to obtain a water-containing crumb; a washing step for washing the water-containing crumb; and a drying step for drying the washed water-containing crumb. A manufacturing method is provided.
In the method for producing acrylic rubber of the present invention, the amount of the coagulant added 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 acrylic rubber according to the present invention, it is preferable that the emulsion polymerization liquid before coagulation further includes 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 acrylic rubber and a crosslinking agent, and a rubber crosslinked product obtained by crosslinking such an acrylic rubber composition.

ADVANTAGE OF THE INVENTION According to this invention, the acrylic rubber which gives the rubber crosslinked material excellent in the compression set resistance and water resistance, and the rubber obtained using such an acrylic rubber and excellent in compression set resistance and water resistance A cross-linked product can be provided.

<Acrylic rubber>
The acrylic rubber of the present invention is a (meth) acrylic acid ester monomer [acrylic acid as a main component in the molecule (in the present invention, having 50% by weight or more in the total monomer units of rubber). An ester monomer and / or a methacrylic acid ester monomer. The same applies to methyl (meth) acrylate. ] A rubbery polymer containing units, wherein the residual amount of coagulant is not less than 10 ppm by weight and not more than 10,000 ppm by weight.

The (meth) acrylic acid ester monomer that forms the (meth) acrylic acid ester monomer unit that is the main component of the acrylic rubber of the present invention is not particularly limited. And (meth) acrylic acid alkoxyalkyl ester monomers.

The (meth) acrylic acid alkyl ester monomer is not particularly limited, but is preferably an ester of an alkanol having 1 to 8 carbon atoms and (meth) acrylic acid, specifically, methyl (meth) acrylate, ( (Meth) ethyl acrylate, (meth) acrylic acid n-propyl, (meth) acrylic acid isopropyl, (meth) acrylic acid n-butyl, (meth) acrylic acid isobutyl, (meth) acrylic acid n-hexyl, (meth) Examples include 2-ethylhexyl acrylate and cyclohexyl (meth) acrylate. Among these, ethyl (meth) acrylate and n-butyl (meth) acrylate are preferable, and ethyl acrylate and n-butyl acrylate are particularly preferable. These can 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. 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, 4-methoxybutyl (meth) acrylate, and the like. Of these, 2-ethoxyethyl (meth) acrylate and 2-methoxyethyl (meth) acrylate are preferable, and 2-ethoxyethyl acrylate and 2-methoxyethyl acrylate are particularly preferable. These can 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 99.99%. 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 resulting rubber cross-linked product may be lowered. There is a risk that the heat resistance of the object will decrease.

In the acrylic rubber of the present invention, the (meth) acrylic acid ester monomer unit includes 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 those comprising 70 to 0% by weight of body units.

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 that forms the crosslinkable monomer unit is not particularly limited. For example, an α, β-ethylenically unsaturated carboxylic acid monomer; a monomer having an epoxy group; a halogen atom Monomer; diene monomer; and the like.

The α, β-ethylenically unsaturated carboxylic acid monomer that forms the α, β-ethylenically unsaturated carboxylic acid monomer unit is not particularly limited, but examples thereof include 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. By using the α, β-ethylenically unsaturated carboxylic acid monomer, the acrylic rubber can be converted into a carboxyl group-containing acrylic rubber having a carboxyl group as a crosslinking point, and thus a rubber cross-linked product can be obtained. Further, 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 butenedionic acid such as fumaric acid and maleic acid; itaconic acid; citraconic acid; chloromaleic acid;
Specific examples of monoesters of α, β-ethylenically unsaturated dicarboxylic acids having 4 to 12 carbon atoms and alkanols having 1 to 8 carbon atoms include monomethyl fumarate, monoethyl fumarate, mono n-butyl fumarate, malein Butenedionic acid mono-chain alkyl esters such as monomethyl acid, monoethyl maleate, and mono-n-butyl maleate; monocyclopentyl fumarate, monocyclohexyl fumarate, monocyclohexenyl fumarate, monocyclopentyl maleate, monocyclohexyl maleate, maleate And butenedionic acid monoesters having an alicyclic structure such as acid monocyclohexenyl; itaconic acid monoesters such as monomethyl itaconate, monoethyl itaconate, mono n-butyl itaconate, and monocyclohexyl itaconate;
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 preferred is mono n-butyl fumarate. These α, β-ethylenically unsaturated carboxylic acid monomers can be used alone or in combination of two or more. Among the above monomers, dicarboxylic acids include those that exist as anhydrides.

Although it does not specifically limit as a monomer which has an epoxy group, For example, Epoxy group containing (meth) acrylic acid ester, such as glycidyl (meth) acrylate; Epoxy group containing ethers, such as allyl glycidyl ether and vinyl glycidyl ether; Is mentioned.

Although it does not specifically limit as a monomer which has a halogen atom, For example, unsaturated alcohol ester of a halogen-containing saturated carboxylic acid, (meth) acrylic acid haloalkyl ester, (meth) acrylic acid haloacyloxyalkyl ester, (meth) acrylic Examples include acid (haloacetylcarbamoyloxy) alkyl esters, halogen-containing unsaturated ethers, halogen-containing unsaturated ketones, halomethyl group-containing aromatic vinyl compounds, halogen-containing unsaturated amides, and haloacetyl group-containing unsaturated monomers.

Specific examples of the unsaturated alcohol ester of a halogen-containing saturated carboxylic acid include vinyl chloroacetate, vinyl 2-chloropropionate, and allyl chloroacetate.
Specific examples of (meth) acrylic acid haloalkyl esters include chloromethyl (meth) acrylate, 1-chloroethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 1,2-dichloroethyl (meth) acrylate. , 2-chloropropyl (meth) acrylate, 3-chloropropyl (meth) acrylate, and 2,3-dichloropropyl (meth) acrylate.
Specific examples of (meth) acrylic acid haloacyloxyalkyl esters 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 esters 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, and p-chloromethyl-α-methylstyrene.

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 chloroacetate.

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

Among the 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 making the acrylic rubber into a carboxyl group-containing 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. It is. By setting the content of the crosslinkable monomer unit within the above range, the compression set resistance can be more appropriately increased while the mechanical properties and heat resistance of the resulting rubber cross-linked product are improved.

In addition to the (meth) acrylic acid ester monomer unit and the crosslinkable monomer unit used as necessary, the acrylic rubber of the present invention has other monomer units copolymerizable therewith. You may do it. 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 aromatic vinyl monomers include styrene, α-methylstyrene, divinylbenzene and the like.

Examples of the α, β-ethylenically unsaturated nitrile monomer include acrylonitrile and methacrylonitrile.
Examples of acrylamide monomers 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.

Other monomers that can be copolymerized can be used singly 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 still more preferably 3,500. The lower limit of the residual amount of the coagulant is 10 ppm by weight or more. The acrylic rubber of the present invention is obtained by emulsion polymerization of the above monomers, and a coagulant is usually used when coagulating an emulsion polymerization solution obtained by emulsion polymerization. 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 setting the residual amount of the coagulant in the acrylic rubber within the above range, the compression set and water resistance in the case of a rubber cross-linked product are excellent. It is something that can be done. In the acrylic rubber of the present invention, it is preferable that the residual amount of the coagulant is small. Therefore, there is a method for reducing the residual amount of the coagulant in the acrylic rubber by reducing the amount of the coagulant used at the time of coagulation. Although it is considered, the coagulation becomes insufficient, the recovery rate of acrylic rubber deteriorates or it is necessary to increase the amount of water washing, so from the viewpoint of stable production, the residual amount of coagulant in acrylic rubber is preferably 200 ppm by weight or more, more preferably 500 ppm by weight or more. The residual amount of the coagulant can be determined, for example, by performing elemental analysis on acrylic rubber and measuring the content of the element contained in the coagulant. In addition, the method for setting the residual amount of the coagulant as described above is not particularly limited, but in the method for producing acrylic rubber described later, a method for appropriately selecting a preferred embodiment as a method for reducing the residual amount of the coagulant, Examples include a method of appropriately combining such aspects.

The coagulant is not particularly limited, and examples thereof include monovalent to trivalent metal salts. 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. For example, 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 or the like with a metal selected from sodium, potassium, lithium, magnesium, calcium, zinc, titanium, manganese, iron, cobalt, nickel, aluminum, tin and the like. Further, hydroxides of these metals can also be used.

Specific examples of 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; nitrates such as 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; sodium sulfate And sulfates such as potassium sulfate, lithium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, titanium sulfate, manganese sulfate, iron sulfate, cobalt sulfate, nickel sulfate, aluminum sulfate and tin sulfate; Among these, calcium chloride, sodium chloride, aluminum sulfate, magnesium chloride, magnesium sulfate, zinc chloride, zinc sulfate, and sodium sulfate are preferable. Of these, 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 multiple types.

The acrylic rubber of the present invention is such that 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 in the case of a rubber cross-linked product can be further increased. Preferably, it is 20,000 ppm by weight or less, more preferably 18,000 ppm by weight or less, and particularly preferably 17,000 ppm by weight or less. Although the minimum of the residual amount of an emulsifier is not specifically limited, Preferably it is 10 weight ppm or more, More preferably, it is 200 weight ppm or more, More preferably, it is 500 weight ppm or more. The acrylic rubber of the present invention is obtained by emulsion polymerization of the above monomers, 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 in the case of a rubber cross-linked product can be further increased. In addition, the residual amount of an emulsifier can be calculated | required from the peak area of the molecular weight corresponding to an emulsifier in the measurement chart obtained by performing GPC measurement with respect to acrylic rubber, for example. The method of setting the residual amount of the emulsifier as described above is not particularly limited. For example, as described later, a nonionic emulsifier and an anionic emulsifier are used in combination as an emulsifier, and the addition amount is described later. The method of making it the range to perform is mentioned.

Further, as described above, the acrylic rubber of the present invention contains a coagulant, 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, more preferably 98% by weight or more. That is, the acrylic rubber of the present invention can be said to be an acrylic rubber composition containing 95% by weight or more (more preferably 97% by weight or more, more preferably 98% by weight or more) of an acrylic rubber component.

<Method for producing acrylic rubber>
The acrylic rubber of the present invention can be produced, for example, by the following production method. That is,
An emulsion polymerization step of obtaining an emulsion polymerization liquid by emulsion polymerization of a monomer for forming an acrylic rubber; and
A coagulation step of adding a coagulant to the emulsion polymerization liquid to obtain a hydrous crumb;
A cleaning step of cleaning the water-containing crumb;
A drying process for drying the washed hydrous crumb;
A method for producing acrylic rubber comprising:

<Emulsion polymerization process>
The emulsion polymerization step in the above production method is a step of obtaining an emulsion polymerization solution by emulsion polymerization of a monomer for forming an acrylic rubber.

As the emulsion polymerization method in the emulsion polymerization step, an ordinary 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. For example, polyoxyethylene alkyl ethers such as polyoxyethylene dodecyl ether, polyoxyethylene alkyl phenol ethers such as polyoxyethylene nonylphenyl ether, and polyoxyethylene alkyls such as polyoxyethylene stearate. Nonionic emulsifiers such as esters, polyoxyethylene sorbitan alkyl esters, polyoxyethylene polyoxypropylene copolymers; salts of fatty acids such as myristic acid, palmitic acid, oleic acid, linolenic acid, alkylbenzene sulfones such as sodium dodecylbenzene sulfonate Acid salts, higher alcohol sulfates such as sodium lauryl sulfate, higher phosphate esters such as sodium alkyl phosphate, Anionic emulsifiers such as Rusuruhokohaku salt; and the like; alkyl trimethyl ammonium chloride, dialkyl ammonium chloride, cationic emulsifiers such as ammonium chloride. These emulsifiers can be used alone or in combination of two or more. Among these nonionic emulsifiers, polyoxyethylene polypropylene glycol, polyethylene glycol monostearate, polyoxyethylene alkyl ether, and polyoxyethylene alkylphenol ether are preferable. As the nonionic emulsifier, those having a weight average molecular weight of less than 10,000 are preferable, those having a weight average molecular weight of 500 to 8000 are more preferable, and those having a weight average molecular weight of 600 to 5000 are more preferable. Among these anionic emulsifiers, higher phosphate ester salts and higher alcohol sulfate ester salts are preferred.

Among these emulsifiers, nonionic emulsifiers and anionic emulsifiers are preferable, and a nonionic emulsifier and an anionic emulsifier are preferably used in combination. By using a combination of a nonionic emulsifier and an anionic emulsifier, it is used in a coagulation step described later while effectively suppressing the occurrence of dirt due to adhesion of a polymer to a polymerization apparatus (for example, a polymerization tank) during emulsion polymerization. The amount of coagulant used can be reduced, and as a result, the amount of coagulant in the finally obtained acrylic rubber can be reduced.

Also, 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 can also be reduced, and as a result, in the acrylic rubber finally obtained The residual amount of the emulsifier contained in can be reduced, whereby the water resistance of the resulting acrylic rubber can be further increased.

In the above production method, the amount of the emulsifier used is the total amount of the emulsifier used with respect to 100 parts by weight of the monomer used for the polymerization, preferably 0.1 to 5 parts by weight, more preferably 0.5 to 4 parts by weight, The amount is preferably 1 to 3 parts by weight. In the case of using a combination of a nonionic emulsifier and an anionic emulsifier, the amount of the nonionic emulsifier used is more than 0 parts by weight, preferably 0. 1 to 3 parts by weight, more preferably 0.5 to 2 parts by weight, still more preferably 0.7 to 1.7 parts by weight. 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. In addition, when the nonionic emulsifier is used in combination with the 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 preferred is 25/75 to 75/25, still more preferred is 50/50 to 75/25, and even more preferred is 65/35 to 75/25.

As polymerization initiators, azo compounds such as azobisisobutyronitrile; organic peroxides such as diisopropylbenzene hydroperoxide, cumene hydroperoxide, paramentane hydroperoxide, benzoyl peroxide; sodium persulfate, persulfate Inorganic peroxides such as potassium, hydrogen peroxide, and ammonium persulfate; can be used. These polymerization initiators can be used alone or in combination of two or more. 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 the organic peroxide and the inorganic peroxide as the polymerization initiator as a redox polymerization initiator in combination with a reducing agent. Although it does not specifically limit as a reducing agent used in combination, The compound containing metal ions in a reduced state, such as ferrous sulfate, sodium hexamethylenediamine tetraacetate, cuprous naphthenate; ascorbic acid, sodium ascorbate Ascorbic acid (salt) such as potassium ascorbate; Erythorbic acid (salt) such as erythorbic acid, sodium erythorbate, potassium erythorbate; saccharides; Sulphinates such as sodium hydroxymethanesulfinate; Sodium hydrogen hydride, sodium aldehyde sodium hydrogen sulfite, potassium hydrogen sulfite; pyrosulfites such as sodium pyrosulfite, potassium pyrosulfite, sodium hydrogen bisulfite, potassium hydrogen bisulfite; sodium thiosulfate Thiosulfates such as potassium thiosulfate; phosphorous acid, sodium phosphite, potassium phosphite, sodium hydrogen phosphite, potassium hydrogen phosphite (salt); pyrophosphorous acid, sodium pyrophosphite, potassium pyrophosphite, Examples thereof include pyrophosphorous acid (salt) such as sodium hydrogen pyrophosphite and potassium hydrogen pyrophosphite; 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 parts by weight with respect to 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 salt, 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 with respect to 100 parts by weight of the monomer used for the polymerization.

In the emulsion polymerization, polymerization auxiliary materials such as a molecular weight adjusting agent, a particle size adjusting agent, a chelating agent, and an oxygen scavenger can be used as necessary.

The emulsion polymerization may be carried out by any of batch, semi-batch and continuous methods, but the semi-batch method is preferred. Specifically, in the reaction system containing the polymerization initiator and the reducing agent, the polymerization reaction is performed while continuously dropping the monomer used for the polymerization to the polymerization reaction system from the start of the polymerization reaction to an arbitrary time. In addition, for at least one of the monomers used for the polymerization, the polymerization initiator, and the reducing agent, it is preferable to perform the polymerization reaction while continuously dropping into the polymerization reaction system from the start of the polymerization reaction to any time, It is more preferable to perform the polymerization reaction while continuously dropping the monomer, polymerization initiator, and reducing agent used for the polymerization from the start of the polymerization reaction to an arbitrary time while continuously dropping into the polymerization reaction system. By carrying out the polymerization reaction while continuously dropping them, emulsion polymerization can be carried out stably, and thereby the polymerization reaction rate can be improved. The polymerization is usually performed in a temperature range of 0 to 70 ° C., preferably 5 to 50 ° C.

In addition, when the polymerization reaction is performed while continuously dropping the monomer used for polymerization, the monomer used for polymerization is mixed with an emulsifier and water to form a monomer emulsion, It is preferable to drop continuously in the state of an emulsion. The method for preparing the monomer emulsion is not particularly limited, and includes a method of stirring the total amount of monomers used for polymerization, the total amount of emulsifier, and water using a stirrer such as a homomixer or a disk turbine. 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 with respect to 100 parts by weight of the monomer used for the polymerization.

In addition, when the polymerization reaction is carried out while continuously dropping into the polymerization reaction system from the start of the polymerization reaction to an arbitrary time for all of the monomer, polymerization initiator, and reducing agent used for the polymerization, these are separate. Or at least the polymerization initiator and the reducing agent may be mixed in advance and, if necessary, dropped into the polymerization system from the same dropping device as an aqueous solution. May be. After completion of 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 solution obtained by the emulsion polymerization step.

The coagulant is not particularly limited, and for example, the above-described monovalent to trivalent metal salts can be suitably 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, still more preferably 3 to 20 parts by weight, particularly preferably 3 to 12 parts by weight. If the amount of the coagulant is too small, the coagulation becomes insufficient and the yield of the acrylic rubber is deteriorated. On the other hand, if the amount is too large, the residual amount of the coagulant in the finally obtained acrylic rubber becomes too large. Water resistance will deteriorate.

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

In addition, when producing the acrylic rubber of the present invention, some of the compounding agents to be blended with the acrylic rubber in the emulsion polymerization liquid before solidifying by adding a coagulant, specifically, aging 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 anti-aging agent, the lubricant, and the ethylene oxide polymer is already mixed in the emulsion polymerization solution, and the emulsion polymerization solution containing these is coagulated.

In particular, the deterioration of the acrylic rubber due to heat at the time of drying in the drying step described later can be effectively suppressed by preliminarily blending the anti-aging agent in the emulsion polymerization liquid before coagulation. Specifically, the decrease in Mooney viscosity due to deterioration due to heating during drying can be effectively suppressed, and further, the effect of normal tensile strength, breaking elongation, etc. when rubber cross-linked products are used. Can be enhanced. In addition, since the anti-aging agent can be appropriately dispersed by blending the anti-aging agent in the state of the emulsion polymerization liquid, the effect of adding the anti-aging agent is sufficient even when the amount of the anti-aging agent is reduced. It can be made to exhibit. Specifically, the blending amount of the antioxidant is preferably 0.1 to 2 parts by weight, more preferably 0.2 to 1.2 parts by weight with respect to 100 parts by weight of the acrylic rubber component in the emulsion polymerization liquid. Even when the amount is relatively small, the effect of the addition can be sufficiently exhibited. Even if the anti-aging agent is previously blended in the emulsion polymerization liquid before coagulation, the pre-blended anti-aging agent is not substantially removed in the subsequent coagulation, washing, drying, etc. For this reason, even when pre-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-butylfunol), 2,2'-methylene-bis (4-methyl-6-t-butylphenol), 3- (3 Butylation reaction of stearyl 5-di-tert-butyl-4-hydroxyphenyl) propionate, alkylated bisphenol, p-cresol and dicyclopentadiene Phenol-based antioxidants containing no sulfur atom, such as reaction products; 2,4-bis [(octylthio) methyl] -6-methylphenol, 2,2′-thiobis- (4-methyl-6-t-butylphenol) ), 4,4′-thiobis- (6-tert-butyl-o-cresol), 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazine Thiobisphenol-based antioxidants such as -2-ylamino) phenol; phosphite-based antioxidants such as tris (nonylphenyl) phosphite, diphenylisodecyl phosphite, tetraphenyldipropylene glycol diphosphite; thiodipropionic acid Sulfur ester anti-aging agents such as dilauryl; 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-p-phenylenediamine, Amine-based antioxidants such as butyraldehyde-aniline condensates; Imidazole-based antioxidants such as 2-mercaptobenzimidazole; Quinoline-based aging such as 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline Inhibitors; hydroquinone anti-aging agents such as 2,5-di- (t-amyl) hydroquinone; and the like. These anti-aging agents may be used alone or in combination of two or more.

In addition, by pre-blending the lubricant in the emulsion polymerization liquid before coagulation, the tack of the finally obtained acrylic rubber can be lowered and mixed with various compounding agents using a mixing device such as a roll. In doing so, adhesion to a mixing device such as a roll can be suitably suppressed, thereby improving productivity. In other words, a method of adding a lubricant when blending various compounding agents into an acrylic rubber using a mixing device such as a roll is also conceivable. However, in this method, the lubricant is dispersed at the initial stage of mixing by the roll. Because it is insufficient, sticking to the roll will occur, and as a result, the mixing time by the roll will be long, while by pre-blending the lubricant in the emulsion polymerization liquid before coagulation, Since the sticking 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 blending the lubricant in the state of the emulsion polymerization liquid, even when the blending amount of the lubricant is reduced, the addition effect can be sufficiently exhibited. Is. Specifically, the blending amount of the lubricant is relatively small, preferably 0.1 to 2 parts by weight, more preferably 0.2 to 1 part by weight, with respect to 100 parts by weight of the acrylic rubber component in the emulsion polymerization liquid. Also as a compounding quantity, the addition effect can fully be exhibited. Even if the lubricant is pre-mixed in the emulsion polymerization liquid before coagulation, the pre-mixed lubricant is not substantially removed in the subsequent coagulation, washing, drying, etc. Even when pre-blended in the liquid, the effect of addition can be sufficiently exhibited.

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

Furthermore, by preliminarily blending the ethylene oxide polymer in the emulsion polymerization solution before coagulation, the coagulation property of the emulsion polymerization solution can be improved, thereby reducing the amount of coagulant in the coagulation step. Since it can do, the residual amount in the acrylic rubber finally obtained can be reduced, and when it is set as a rubber cross-linked product, compression set resistance and water resistance can be further improved. The ethylene oxide polymer is not particularly limited as long as it is a polymer having a polyethylene oxide structure as the main chain structure, and examples thereof include polyethylene oxide, polypropylene oxide, and ethylene oxide / propylene oxide copolymers. 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 with respect to 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, more preferably 20,000 to 120,000.

The order of addition in the case of adding an antioxidant, a lubricant and an ethylene oxide polymer to the emulsion polymerization solution before coagulation is not particularly limited, and may be appropriately selected.

And even when these anti-aging agent, lubricant and / or ethylene oxide polymer are blended in the emulsion polymerization liquid before coagulation in advance, a coagulant is added to the emulsion polymerization liquid under the same conditions as described above. By performing the solidification operation, a hydrous crumb can be obtained.

<Washing process>
The washing step in the above production method is a step of washing the water-containing crumb obtained in the above-described coagulation step.

The washing method is not particularly limited, and examples thereof include a method of washing with water by using water as a washing liquid and mixing the added water together with the hydrated crumb. 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.

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

The number of times of washing with water is not particularly limited, and may be one, but is preferably 2 to 10 times, more preferably 3 to 8 from the viewpoint of reducing the residual amount of coagulant in the finally obtained acrylic rubber. Times. In addition, from the viewpoint of reducing the residual amount of coagulant in the finally obtained acrylic rubber, it is desirable that the number of times of washing with water is large. On the other hand, it is preferable that the number of washings is in the above range because the influence of the decrease in productivity is increased by increasing the number of steps.

In the present invention, after washing with water, acid washing using an acid as a washing solution may be performed. By performing the acid cleaning, the compression set resistance in the case of a rubber cross-linked product can be further improved. When the acrylic rubber is a carboxyl group-containing acrylic rubber having a carboxyl group, this acid cleaning The effect of improving the compression set resistance is particularly great. The acid used for the acid cleaning is not particularly limited, and sulfuric acid, hydrochloric acid, phosphoric acid and the like can be used without limitation. In addition, when acid is added to water-containing crumbs in acid washing, it is preferably added in the form of an aqueous solution, preferably pH = 6 or less, more preferably pH = 4 or less, and even more preferably pH = 3 or less. It is preferable to add in the state of aqueous solution. The acid washing method is not particularly limited, and examples thereof include a method of mixing an aqueous solution of the added acid together with water-containing crumb.

The temperature during the acid cleaning 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 the 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 acid-washed wash water can be determined, for example, by measuring the pH of the water contained in the hydrous crumb after the acid wash.

After the acid cleaning, it is preferable to perform further water washing, and the water washing conditions may be the same as those described above.

<Drying process>
In the production method, the drying step is a step of drying the water-containing crumb that has been washed in the washing step.

Although it does not specifically limit as a drying method in a drying process, For example, it can be dried using dryers, such as a screw type extruder, a kneader type dryer, an expander dryer, a hot air dryer, and a vacuum dryer. . Moreover, you may use the drying method which combined these. Furthermore, before performing drying in the drying step, 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., 100 More preferably, the temperature is set to ˜170 ° C.

According to the above production 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 thus produced 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, still more preferably 0. .2 to 0.3% by weight. By controlling the residual amount of the lubricant within the above range, it is possible to more effectively improve the handleability and roll processability when drying the acrylic rubber while suppressing the occurrence of bleeding. The residual amount of the lubricant can be obtained by dissolving the acrylic rubber in tetrahydrofuran and performing GPC measurement using tetrahydrofuran as a developing solvent. Specifically, the integrated value of the peak corresponding to the molecular weight of the lubricant is obtained from the chart obtained by the GPC measurement, the integrated value is compared with the integrated value of the peak of the acrylic rubber, and these integrated values correspond. By determining the weight ratio from the molecular weight to be determined, the content of the lubricant can be determined.

Further, 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, and further preferably 2,000 ppm by weight. That's it. The upper limit of the content of the antioxidant is not particularly limited, but is preferably 12,000 ppm by weight or less. By setting the residual amount of the anti-aging agent in the above range, it is possible to more appropriately prevent the occurrence of deterioration due to drying, and thereby it is possible to further increase the tensile strength of the obtained rubber cross-linked product. In addition, the residual amount of an anti-aging agent can be calculated | required from the peak area of the molecular weight corresponding to an anti-aging agent in the measurement chart obtained by performing GPC measurement with respect to acrylic rubber, for example.

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

Although it does not specifically limit as a crosslinking agent, For example, polyvalent amine compounds, such as a diamine compound, and its carbonate; Sulfur; Sulfur donor; Triazine thiol compound; Multivalent epoxy compound; Organic carboxylic acid ammonium salt; Conventionally known crosslinking agents such as oxides, dithiocarbamic acid metal salts, polyvalent carboxylic acids, quaternary onium salts, imidazole compounds, isocyanuric acid compounds, and organic peroxides can be used. These crosslinking agents can be used alone or in combination of two or more. The crosslinking agent is preferably selected as appropriate according to the type of the crosslinkable 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 carbonate thereof are not particularly limited, but polyvalent amine compounds having 4 to 30 carbon atoms and carbonates thereof are preferred. Examples of such polyvalent amine compounds and carbonates thereof include aliphatic polyvalent amine compounds, carbonates thereof, and aromatic polyvalent amine compounds.

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

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

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 parts by weight with respect to 100 parts by weight of the acrylic rubber. 2 to 4 parts by weight. By setting the content of the cross-linking agent in the above range, the mechanical strength as a rubber cross-linked product can be made excellent while the rubber elasticity is sufficient.

The acrylic rubber composition of the present invention preferably further contains a crosslinking accelerator. The crosslinking accelerator is not particularly limited, but when the acrylic rubber of the present invention has a carboxyl group as a crosslinkable group and the crosslinking 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, aliphatic monovalent tertiary amine compounds, and the like can be used. 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 singly or in combination of two or more.

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

An aliphatic monovalent secondary amine compound is a compound in which two hydrogen atoms of ammonia are substituted with an aliphatic hydrocarbon group. The aliphatic hydrocarbon group substituted for the hydrogen atom is preferably one having 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, di Examples include heptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine, ditridecylamine, ditetradecylamine, dipentadecylamine, dicetylamine, di-2-ethylhexylamine, and dioctadecylamine.

An aliphatic monovalent tertiary amine compound is a compound in which all three hydrogen atoms of ammonia are substituted with an aliphatic hydrocarbon group. The aliphatic hydrocarbon group substituted for the hydrogen atom is preferably one having 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, and tridodecylamine.

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 with respect to 100 parts by weight of the acrylic rubber. Parts, particularly preferably 1 to 5 parts by weight. By making content of a crosslinking accelerator into the said range, the tensile strength and compression set resistance of the rubber crosslinked material obtained can be improved more.

Moreover, the acrylic rubber composition of the present invention can contain a compounding agent usually used in the field of rubber processing, 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; anti-aging agents; light stabilizers; scorch inhibitors; plasticizers; Adhesives; Adhesives; Lubricants; Lubricants; Flame retardants; Antifungal agents; Antistatic agents; Colorants; The compounding amount of these compounding agents is not particularly limited as long as it does not impair the object and effect of the present invention, and an amount corresponding to the compounding purpose can be appropriately compounded.

Furthermore, in the acrylic rubber composition of the present invention, rubbers, elastomers, resins and the like other than the acrylic rubber of the present invention described above may be further blended within a range not impairing the effects of the present invention. For example, rubber other than acrylic rubber such as acrylic rubber other than the acrylic rubber of the present invention, natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, silicon rubber, fluorine rubber, etc .; 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 Resin, polycarbonate resin, polyamide resin, vinyl chloride resin, fluororesin, etc. can be blended. In addition, the total blending amount of the 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, further preferably 100 parts by weight of acrylic rubber. 1 part by weight or less.

In the acrylic rubber composition of the present invention, the acrylic rubber is blended with a crosslinking agent and other various compounding agents used as necessary, mixed and kneaded with a Banbury mixer or a kneader, and then using a kneading roll. Further, it is prepared by kneading.

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

<Rubber cross-linked product>
The rubber cross-linked product of the present invention is obtained by cross-linking the acrylic rubber composition of the present invention described above.
The rubber cross-linked product of the present invention uses the acrylic rubber composition of the present invention, is molded by a molding machine corresponding to a desired shape, for example, an extruder, an injection molding machine, a compressor, and a roll, and is heated. It can be produced by carrying out a cross-linking reaction and fixing the shape as a rubber cross-linked product. In this case, crosslinking may be performed after molding in advance, or crosslinking may be performed simultaneously with molding. 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 of rubber, such as press heating, steam heating, oven heating, and hot air heating, may be appropriately selected.

Further, depending on the shape and size of the rubber cross-linked product, the rubber cross-linked product of the present invention may be further heated to perform secondary crosslinking. The secondary crosslinking varies depending on the heating method, crosslinking temperature, shape, etc., but is preferably performed for 1 to 48 hours. What is necessary is just to select a heating method and heating temperature suitably.

The rubber cross-linked product of the present invention has excellent compression set resistance and water resistance while maintaining the basic properties of rubber such as tensile strength, elongation, and hardness. Therefore, the rubber cross-linked product of the present invention makes use of such characteristics, for example, seals such as O-rings, packings, oil seals, bearing seals and the like in a wide range of transportation machines such as automobiles, general equipment, and electrical equipment. Materials: gaskets; cushioning materials, vibration-proof materials; electric wire covering materials; industrial belts; tubes and hoses; sheets;

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The “parts” in each example are based on weight unless otherwise specified.
Various physical properties were evaluated according to the following methods.

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

[Residual amount of coagulant]
The residual amount of 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 determined by elemental analysis, and the residual amount of the coagulant was calculated from the determined content ratio.

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

[Recovery rate of acrylic rubber]
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 (charge amount) of the monomer used for the polymerization and the polymerization conversion rate is obtained. Was 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 subjected to primary crosslinking by pressing at 170 ° C. for 20 minutes while being pressed at a press pressure of 10 MPa. The product was further subjected to secondary crosslinking by heating at 170 ° C. for 4 hours in a gear-type oven to obtain a sheet-like rubber crosslinked product. The obtained rubber cross-linked product was punched with a No. 3 type 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 produced in the same manner as the test piece used for the evaluation of the above-mentioned normal physical properties was placed in a gear-type oven in an environment at a temperature of 175 ° C. for 504 hours, and then measured for tensile strength and elongation. The heat aging resistance was evaluated by comparing the results with normal physical properties measured according to the above method. Tensile strength and elongation were measured according to JIS K6251.
About tensile strength, the one where the measured value of the sample after a heating is large is excellent in heat resistance. Regarding the elongation, the heat resistance is better when the elongation change rate (percentage), which is the change rate of the measured value of the sample after heating with respect to the measured value (measured value of normal physical properties) of the sample that has not been heat-aged, is close to zero.

[Compression set]
The acrylic rubber composition was subjected to primary crosslinking by pressing 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 crosslinked product was further subjected to secondary crosslinking by heating at 170 ° C. for 4 hours in a gear-type oven to obtain a cylindrical rubber crosslinked product. The obtained rubber cross-linked product was placed in an environment at 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 subjected to primary crosslinking by pressing at 170 ° C. for 20 minutes while being pressed at a press pressure of 10 MPa. The product was further subjected to secondary crosslinking by heating at 170 ° C. for 4 hours in a gear-type oven to obtain a sheet-like rubber crosslinked product. And it cut out into the test piece of 3 cm x 2 cm x 0.2 cm from the obtained sheet-like rubber cross-linked product, and according to JIS K6258, the obtained test piece was adjusted to a temperature of 80 ° C for 70 hours in distilled water. A dipping test was performed, and the volume change rate of the test piece before and after dipping was measured according to the following formula. It can be judged that the smaller the volume change rate before and after the immersion, the lower the swelling with respect to water, and the better the water resistance.
Volume change rate before and after immersion (%) = (Volume of specimen after immersion−Volume of specimen before immersion) ÷ Volume of specimen before immersion × 100

[Production Example 1]
In a mixing vessel equipped with a homomixer, 46.294 parts pure water, 49.3 parts ethyl acrylate, 49.3 parts n-butyl acrylate, 1.4 parts mono-n-butyl fumarate, anionic surfactant Sodium lauryl sulfate (trade name “Emar 2FG”, manufactured by Kao Corporation) 0.709 parts, and polyoxyethylene dodecyl ether (trade name “Emulgen 105”, weight average molecular weight: about 1500, A monomer emulsion was obtained by charging 1.82 parts (made by Kao Corporation) and stirring.

Next, 170.853 parts of pure water and 2.98 parts of the monomer emulsion obtained above were charged into a polymerization reaction tank equipped with a thermometer and a stirrer, and the temperature was 12 ° C. under a nitrogen stream. Until cooled. Next, in the polymerization reaction tank, 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. Thereafter, the reaction was continued for 1 hour while maintaining the temperature in the polymerization reaction vessel at 23 ° C., and it was confirmed that the polymerization conversion rate reached 95%, and polymerization was carried out by adding hydroquinone as a polymerization terminator. The reaction was stopped to obtain an emulsion polymerization solution.

Then, 100 parts of the emulsion polymerization solution obtained by polymerization is stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (trade name “Irganox 1076”, BASF) as an anti-aging agent. Co., Ltd.) 0.3 parts (total of the monomers used in the production of the emulsion polymerization liquid (that is, ethyl acrylate, n-butyl acrylate, mono n-butyl fumarate) 100 parts 1 part), 0.011 part of polyethylene oxide (weight average molecular weight (Mw) = 100,000) (0.039 part with respect to a total of 100 parts of the charged monomers used in producing the emulsion polymerization liquid) ), And polyoxyethylene stearyl ether phosphoric acid (trade name “phosphanol RL-210”, weight average molecular weight: about 500, Toho Chemical Industries, Ltd.) ) Was obtained 0.075 parts (mixture by mixing 0.25 parts per 100 parts of monomer charged) was used in preparing the polymer emulsion. Then, the obtained mixed liquid was transferred to a coagulation tank. To 100 parts of this mixed liquid, 60 parts of industrial water was added and the temperature was raised to 85 ° C., and then the mixed liquid 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 coagulate the polymer, whereby acrylic rubber (A1) Of hydrated crumbs.

Next, 194 parts of industrial water was added to 100 parts of the solid content of the hydrated crumb obtained above, and after stirring for 15 minutes at 15 ° C. in the coagulation tank, the water was discharged from the coagulation tank, The water-containing crumb was washed with water. In this production example, such washing with water was repeated four times.

Next, a sulfuric acid aqueous solution (pH = 3) obtained by mixing 194 parts of industrial water and 0.13 part of concentrated sulfuric acid is added to 100 parts of the solid content of the hydrated crumb which has been washed with water in the above, and in the coagulation tank. After stirring at 15 ° C. for 5 minutes, the water-containing crumb was pickled by draining water from the coagulation tank. The pH of the hydrated crumb after pickling (pH of water in the hydrated crumb) was measured, and the pH was 3. Next, 194 parts of pure water is added to 100 parts of the solid content of the pickled water-containing crumb, and after stirring for 5 minutes at 15 ° C. in the coagulation tank, the water content is discharged from the coagulation tank. The crumb was washed with pure water, and the hydrated crumb that had been washed with pure water was dried with a hot air dryer at 110 ° C. for 1 hour to obtain a solid acrylic rubber (A1).

The resulting acrylic rubber (A1) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 31, the recovery rate of the acrylic rubber (A1) is 100%, and the composition of the acrylic rubber (A1) is 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, about acrylic rubber (A1), the residual amount of the coagulant | flocculant, surfactant, lubricant, and anti-aging agent in acrylic rubber (A1) was measured according to the said method. The results are shown in Table 1.

[Production Example 2]
The amount of sodium lauryl sulfate used as an anionic surfactant is changed from 0.709 parts to 0.624 parts, and the amount of polyoxyethylene dodecyl ether used as a nonionic surfactant is changed from 1.82 parts to 1.5 parts. A monomer emulsion was obtained in the same manner as in Production Example 1, except that each was changed. And solid acrylic rubber (A2) was obtained like manufacture example 1 except having used the obtained monomer emulsified liquid.

The resulting acrylic rubber (A2) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the acrylic rubber (A2) has a recovery rate of 100%, and the composition of the acrylic rubber (A2) has an ethyl acrylate unit of 49.3. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, about acrylic rubber (A2), the residual amount of the coagulant | flocculant, surfactant, lubricant, and anti-aging agent in acrylic rubber (A2) was measured according to the said method. The results are shown in Table 1.

[Production Example 3]
The amount of sodium lauryl sulfate used as an anionic surfactant is changed from 0.709 parts to 0.567 parts, and the amount of polyoxyethylene dodecyl ether used as a nonionic surfactant is 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 each was changed. And solid acrylic rubber (A3) was obtained like manufacture example 1 except having used the obtained monomer emulsified liquid.

The resulting acrylic rubber (A3) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 34, the acrylic rubber (A3) has a recovery rate of 100%, and the composition of the acrylic rubber (A3) has an ethyl acrylate unit of 49.3. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, about acrylic rubber (A3), the residual amount of the coagulant | flocculant, surfactant, lubricant, and anti-aging agent in acrylic rubber (A3) was measured according to the said method. The results are shown in Table 1.

[Production Example 4]
The amount of sodium lauryl sulfate used as an anionic surfactant is changed from 0.709 parts to 0.567 parts, and the amount of polyoxyethylene dodecyl ether used as a nonionic surfactant is 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 each was changed.

Next, 179 parts of pure water and 2.98 parts of the monomer emulsion obtained above were charged into a polymerization reaction tank equipped with a thermometer and a stirrer, and cooled to a temperature of 12 ° C. under a nitrogen stream. Next, 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 collectively charged into the polymerization reaction vessel. Thereafter, 145.29 parts of the monomer emulsion obtained above was continuously dropped into the polymerization reaction tank over 3 hours, and then the temperature in the polymerization reaction tank was maintained at 23 ° C. Then, the reaction was continued for 1 hour, and it was confirmed that the polymerization conversion rate reached 90%. Hydroquinone as a polymerization terminator was added to stop the polymerization reaction, and an emulsion polymerization solution was obtained.

Then, an anti-aging agent and a lubricant are added to the emulsion polymerization liquid obtained above in the same manner as in Production Example 1 and mixed to obtain a liquid mixture, which is similar to the obtained liquid mixture. By performing the coagulation operation as described above, a water-containing crumb of acrylic rubber (A4) was obtained, and the obtained water-containing crumb was similarly subjected to four times of water washing, pickling, pure water washing and drying, A solid acrylic rubber (A4) was obtained.

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

[Production Example 5]
An emulsion polymerization solution 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, an anti-aging agent and a lubricant are added to and mixed with the obtained emulsion polymerization liquid in the same manner as in Production Example 1 to obtain a mixed liquid, and the resulting mixed liquid is coagulated in the same manner. By performing the operation, a water-containing crumb of acrylic rubber (A5) was obtained.

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

[Production Example 6]
An emulsion polymerization solution 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, an anti-aging agent and a lubricant are added to and mixed with the obtained emulsion polymerization liquid in the same manner as in Production Example 1 to obtain a mixed liquid, and the resulting mixed liquid is coagulated in the same manner. By performing the operation, a water-containing crumb of acrylic rubber (A6) was obtained.

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

[Production Example 7]
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 as a coagulant used for the coagulation operation. Obtained. Next, the obtained water-containing crumb was subjected to washing with water, pickling, washing with pure water and drying in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A7).

The resulting acrylic rubber (A7) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the recovery rate of the acrylic rubber (A7) is 100%, and the composition of the acrylic rubber (A7) is 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, the residual amount of the coagulant, surfactant, lubricant, and anti-aging agent in the acrylic rubber (A7) was measured according to the above method. The results are shown in Table 1.

[Production Example 8]
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 as a coagulant used for the coagulation operation. Obtained. Subsequently, the obtained water-containing crumb was subjected to washing with water, pickling, washing with pure water and drying in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A8).

The resulting acrylic rubber (A8) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 35, the recovery rate of the acrylic rubber (A8) is 100%, and the composition of the acrylic rubber (A8) is 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, the residual amount of the coagulant | flocculant, surfactant, lubricant, and anti-aging agent in acrylic rubber (A8) was measured according to the said method. The results are shown in Table 1.

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

Next, the obtained water-containing crumb was subjected to washing with water, pickling, washing with pure water and drying in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A9). The resulting acrylic rubber (A9) had a Mooney viscosity (ML1 + 4, 100 ° C.) of 34, the recovery rate of the acrylic rubber (A9) was 100%, and the composition of the acrylic rubber (A9) was 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, the residual amount of the coagulant, surfactant, lubricant, and anti-aging agent in the acrylic rubber (A9) was measured according to the above method. The results are shown in Table 1.

[Production Example 10]
As an antioxidant to be blended with 100 parts by weight of the emulsion polymerization solution obtained by polymerization, instead of 0.3 part of stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 0.3 parts of 2-mercaptobenzimidazole (trade name “NOCRACK MB”, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) (1 part for a total of 100 parts of the charged monomers used to produce the emulsion polymerization liquid) ) Was used in the same manner as in Production Example 3 to obtain a hydrated crumb of acrylic rubber (A10).

Next, the obtained water-containing crumb was subjected to washing with water, pickling, washing with pure water and drying in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A10). The resulting acrylic rubber (A10) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the acrylic rubber (A10) has a recovery rate of 100%, and the composition of the acrylic rubber (A10) is ethyl acrylate units 49.3. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, the residual amount of the coagulant | flocculant, surfactant, lubricant, and anti-aging agent in acrylic rubber (A10) was measured according to the said method. The results are shown in Table 1.

[Production Example 11]
As an antioxidant to be blended with 100 parts by weight of the emulsion polymerization solution obtained by 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 “NOCRACK CD”, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) 0.3 part (single amount used for preparing the emulsion polymerization liquid) 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 a total of 100 parts of the body.

Subsequently, the obtained water-containing crumb was subjected to washing with water, pickling, washing with pure water and drying in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A11). The resulting acrylic rubber (A11) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 32, the acrylic rubber (A11) has a recovery rate of 100%, and the composition of the acrylic rubber (A11) is 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, the residual amount of the coagulant | flocculant, surfactant, lubricant, and anti-aging agent in acrylic rubber (A11) was measured according to the said method. The results are shown in Table 1.

[Production Example 12]
As an antioxidant to be blended with 100 parts by weight of the emulsion polymerization solution obtained by 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 “NOCRACK SP”, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 0.3 part (single amount of preparation used for producing emulsion polymerization liquid) 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 with respect to 100 parts in total.

Subsequently, the obtained water-containing crumb was subjected to washing with water, pickling, washing with pure water and drying in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A12). The resulting acrylic rubber (A12) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 31, the recovery rate of the acrylic rubber (A12) is 100%, and the composition of the acrylic rubber (A12) is 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, the residual amount of the coagulant, surfactant, lubricant, and anti-aging agent in the acrylic rubber (A12) was measured according to the above method. The results are shown in Table 1.

[Production Example 13]
As a lubricant to be blended with respect to 100 parts by weight of the emulsion polymerization solution obtained by the polymerization, instead of 0.075 part of polyoxyethylene stearyl ether phosphoric acid, a higher fatty acid (trade name “Moldwiz Int21G”, manufactured by Sakai Kogyo Co., Ltd.) 0 Acrylic rubber (A13) in the same manner as in Production Example 1 except that 0.075 part (0.25 part with respect to a total of 100 parts of charged monomers used in producing the emulsion polymerization liquid) was used. Of hydrated crumbs.

Subsequently, the obtained water-containing crumb was subjected to washing with water, pickling, pure water, and drying in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A13). The resulting acrylic rubber (A13) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the acrylic rubber (A13) has a recovery rate of 100%, and the composition of the acrylic rubber (A13) has an ethyl acrylate unit of 49.3. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, the residual amount of the coagulant | flocculant, surfactant, lubricant, and anti-aging agent in acrylic rubber (A13) was measured according to the said method. The results are shown in Table 1.

[Production Example 14]
As a lubricant to be blended with respect to 100 parts by weight of the emulsion polymerization solution obtained by the polymerization, instead of 0.075 part of polyoxyethylene stearyl ether phosphoric acid, a higher fatty acid (trade name “Moldwiz Int21G”, manufactured by Sakai Kogyo Co., Ltd.) 0 0.075 part (0.25 part with respect to a total of 100 parts of the charged monomers used for producing the emulsion polymerization solution) and sodium coagulant 3 as a coagulant used for coagulation operation A hydrous 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 3 parts.

Subsequently, the obtained water-containing crumb was subjected to washing with water, pickling, washing with pure water and drying in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A14). The resulting acrylic rubber (A14) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the acrylic rubber (A14) has a recovery rate of 100%, and the composition of the acrylic rubber (A14) has an ethyl acrylate unit of 49.3. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, the residual amount of the coagulant, surfactant, lubricant and anti-aging agent in the acrylic rubber (A14) was 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 for the coagulation operation was changed from 3.3 parts to 0.3 parts (1 part with respect to 100 parts of the polymer contained in the mixed solution). In the same manner as in Example 13, a water-containing crumb of acrylic rubber (A15) was obtained. Subsequently, the obtained water-containing crumb was subjected to washing with water, pickling, washing with pure water and drying in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A15).

The resulting acrylic rubber (A15) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the acrylic rubber (A15) has a recovery rate of 42%, and the composition of the acrylic rubber (A15) has an ethyl acrylate unit of 49.3. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, the residual amount of the coagulant, surfactant, lubricant, and anti-aging agent in the acrylic rubber (A15) was 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 the coagulant used in the coagulation operation was changed from 3.3 parts to 0.6 parts (2 parts with respect to 100 parts of the polymer contained in the mixed solution). In the same manner as in Example 13, a water-containing crumb of acrylic rubber (A16) was obtained. Subsequently, the obtained water-containing crumb was subjected to washing with water, pickling, washing with pure water and drying in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A16).

The resulting acrylic rubber (A16) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the recovery rate of the acrylic rubber (A16) is 63%, and the composition of the acrylic rubber (A16) has an ethyl acrylate unit of 49.3. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, the residual amount of the coagulant, surfactant, lubricant, and anti-aging agent in the acrylic rubber (A16) was 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 the coagulant used in the coagulation operation was changed from 3.3 parts to 10 parts (33.3 parts relative to 100 parts of the polymer contained in the mixed solution). In the same manner as in Example 13, a water-containing crumb of acrylic rubber (A17) was obtained. Next, the obtained water-containing crumb was subjected to washing with water, pickling, washing with pure water and drying in the same manner as in Production Example 1 to obtain a solid acrylic rubber (A17).

The resulting acrylic rubber (A17) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the recovery rate of the acrylic rubber (A17) is 100%, and the composition of the acrylic rubber (A17) is 49.3 ethyl acrylate units. % By weight, n-butyl acrylate unit 49.3% by weight, and mono n-butyl fumarate unit 1.4% by weight. Moreover, the residual amount of the coagulant, surfactant, lubricant, and anti-aging agent in the acrylic rubber (A17) was 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 ", Evonik 15 parts, silica (trade name" Carplex 67 ", Evonik) 35 parts, stearic acid 2 parts, ester wax (trade name" Greg G-8205 ", Dainippon Ink Chemical Co., Ltd.) 1 part, 4,4′-bis (α, α-dimethylbenzyl) diphenylamine (trade name “NOCRACK CD”, Ouchi Shinsei 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. Subsequently, the obtained mixture was transferred to a roll at 50 ° C., and 0.6 parts of hexamethylenediamine carbamate (trade name “Diak # 1”, manufactured by DuPont Dow Elastomer Co., Ltd., aliphatic polyvalent amine compound) and 1,3 -2 parts of di-o-tolylguanidine (trade name “Noxeller DT”, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., crosslinking accelerator) was blended and kneaded to obtain an acrylic rubber composition.

Then, using the obtained acrylic rubber composition, according to the above methods, normal properties, thermal aging test, compression set, and water resistance were measured and evaluated. The results are shown in Table 2.

[Examples 2 to 16]
In the same manner as in Example 1 except that the acrylic rubbers (A2) to (A16) obtained in Production Examples 2 to 16 were used in place of the acrylic rubber (A1) obtained in Production Example 1, respectively. Table 2 shows the results of measurement and evaluation in the same manner after obtaining 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. The results of measurement / evaluation are shown in Table 2.

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

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

Claims (14)

1. An acrylic rubber having a residual amount of coagulant of 10 ppm by weight or more and 10,000 ppm by weight or less.
2. The acrylic rubber according to claim 1, wherein the residual amount of the coagulant is 10 ppm by weight or more and 3,500 ppm by weight or less.
3. The acrylic rubber according to claim 1 or 2, wherein the residual amount of the coagulant is 500 ppm by weight or more and 3,500 ppm by weight or less.
4. 4. The acrylic rubber according to claim 1, wherein the coagulant is a monovalent to trivalent metal salt.
5. The acrylic rubber according to claim 4, wherein the coagulant is calcium chloride, sodium chloride, magnesium sulfate, or sodium sulfate.
6. The acrylic rubber according to any one of claims 1 to 5, wherein the residual amount of the emulsifier is 10 ppm by weight or more and 22,000 ppm by weight or less.
7. The acrylic rubber according to any one of claims 1 to 6, wherein the residual amount of the lubricant is 0.1 to 0.4% by weight.
8. The acrylic rubber according to any one of claims 1 to 7, wherein the residual amount of the anti-aging agent is 500 ppm by weight or more and 12,000 ppm by weight or less.
9. The acrylic rubber according to any one of claims 1 to 8, wherein the content of the acrylic rubber component is 95% by weight or more.
10. A method for producing the acrylic rubber according to any one of claims 1 to 9,
    An emulsion polymerization step of obtaining an emulsion polymerization liquid by emulsion polymerization of a monomer for forming an acrylic rubber; and
    A coagulation step of adding a coagulant to the emulsion polymerization liquid to obtain a hydrous crumb;
    A cleaning step of cleaning the water-containing crumb;
    A drying process for drying the washed hydrous crumb;
    A method for producing acrylic rubber comprising:
11. The method for producing acrylic rubber according to claim 10, wherein the addition amount of the coagulant 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.
12. The method for producing acrylic rubber according to claim 10 or 11, further comprising an addition step of adding at least one selected from a lubricant, an anti-aging agent and an ethylene oxide polymer to the emulsion polymerization liquid before coagulation.
13. An acrylic rubber composition comprising the acrylic rubber according to any one of claims 1 to 9 and a crosslinking agent.
14. A rubber cross-linked product obtained by cross-linking the acrylic rubber composition according to claim 13.