JP2019194326A - Production of acrylic rubber and obtained acrylic rubber - Google Patents

Abstract

To provide a method for producing an acrylic rubber that can effectively prevent mutual adhesion of hydrous crumbs, has a high polymer recovery rate, has excellent drying property and roll processability, and gives a rubber crosslinked product with excellent water resistance.SOLUTION: The present invention provides a method for producing an acrylic rubber, which comprises: an emulsion polymerization step for obtaining an emulsion polymer solution by emulsion polymerizing a monomer for the formation of the acrylic rubber; and a coagulation step for obtaining hydrated crumbs by coagulating the emulsion polymer solution in the presence of two or more compounds that have polyoxyalkylene skeletons differing in terminal structures, specifically, in the presence of an ester of polyalkylene glycol (A) and polyalkylene glycol (B1) and/or an ether compound of polyalkylene glycol (B2).SELECTED DRAWING: None

Description

  The present invention relates to a method for producing acrylic rubber, and more specifically, can prevent the occurrence of mutual adhesion of water-containing crumbs, has a high polymer recovery rate, is excellent in drying properties and roll processability, and has excellent water resistance. The present invention relates to a method for producing an acrylic rubber capable of providing a rubber cross-linked product having the following.

  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. (For example, refer patent document 1).

  For example, Patent Document 1 discloses that a monomer containing a crosslinkable monomer such as (meth) acrylate and butenoic acid monobutyrate is used as sodium dodecyl sulfate as an anionic emulsifier and polyoxyethylene dodecyl tater as a nonionic emulsifier. In the presence of, the emulsion polymerization solution obtained by emulsion polymerization using a polymerization catalyst consisting of cumene hydroperoxide, ferrous sulfate and sodium formaldehyde sulfoxylate is coagulated by introducing it into 15% saline solution at 80 ° C. Thus, a method for producing acrylic rubber by obtaining crumb, washing with water and drying is disclosed.

  However, in the conventional acrylic rubber such as the acrylic rubber described in Patent Document 1, the water-containing crumbs after coagulation may occur, and such water-containing crumbs adhere. As a result, the efficiency of washing after coagulation is reduced, the drying time when drying the hydrous crumb needs to be lengthened, the polymer recovery rate is deteriorated, the productivity is reduced, When the various compounding agents were blended using a roll, sticking to the roll was likely to occur, and there was a problem that the workability at the time of processing with the roll was insufficient or the water resistance was greatly inferior.

JP 2011-88956 A

  The present invention has been made in view of such a situation, can effectively prevent the occurrence of mutual adhesion of water-containing crumbs, has a high polymer recovery rate, excellent drying and roll processability, and An object of the present invention is to provide a method for producing an acrylic rubber capable of giving a rubber cross-linked product having excellent water resistance.

As a result of diligent research to achieve the above object, the present inventors have a specific structure when solidifying an emulsion polymerization solution obtained by emulsion polymerization of a monomer for forming an acrylic rubber. It has been found that the above object can be achieved by coagulating an emulsion polymerization solution in the presence of a compound having two or more types of polyoxyalkylene skeletons.
The present inventors further remarkably improve the effect of the present invention by setting a specific catalyst, a specific addition time of a compound having two or more types of polyoxyalkylene skeletons, a specific coagulant, and a specific coagulation temperature. Found to improve.
The present inventors have completed the present invention based on these findings.

Thus, according to the present invention, an emulsion polymerization step for obtaining an emulsion polymerization solution by emulsion polymerization of a monomer having (meth) acrylic acid ester as a main component using a polymerization catalyst, ) And a polyalkylene glycol ester (B1) and / or a polyalkylene glycol ether compound (B2) to coagulate to obtain a water-containing crumb, a washing step for washing the water-containing crumb, and a washing There is provided a method for producing acrylic rubber comprising a drying step of drying the hydrous crumb.
In the acrylic rubber production method of the present invention, the polymerization catalyst preferably contains a peroxide, ferrous sulfate, and ascorbic acid (salt).
As a manufacturing method of the acrylic rubber of this invention, it is preferable that addition of the said polyalkylene glycol (A) is an emulsion polymerization liquid after emulsion polymerization.
As the method for producing the acrylic rubber of the present invention, the addition of the polyalkylene glycol ester (B1) and / or the polyalkylene glycol ether compound (B2) may be carried out by the monomer emulsion before emulsion polymerization and / or emulsion polymerization. It is preferable that it is a later emulsion polymerization liquid.

As the method for producing the acrylic rubber of the present invention, the polyalkylene glycol ester (B1) and / or the polyalkylene glycol ether compound (B2) is a polyoxyalkylene phosphate ester, a polyoxyalkylene sulfate ester, or a polyoxyalkylene fatty acid. At least one polyoxyalkylene ester compound selected from the group consisting of esters and polyoxyalkylene ether esters, and / or at least one ester group selected from the group consisting of polyoxyalkylene alkyl ethers and polyoxyalkylene aryl ethers It is preferable that it is a polyoxyalkylene ether compound not having.
As a method for producing the acrylic rubber of the present invention, it is preferable that the emulsion polymerization solution is coagulated by contact between the emulsion polymerization solution and a sulfate compound.
As a manufacturing method of the acrylic rubber of this invention, it is preferable that the coagulation temperature is 60 degreeC or more.

Thus, according to the present invention, the (meth) acrylic acid ester unit obtained by the above production method is 50 to 99.9% by weight, the crosslinkable monomer unit is 0.01 to 20% by weight, and copolymerizable. An acrylic rubber having 0 to 50% by weight of other monomer units is provided.
In the acrylic rubber of the present invention, the crosslinkable monomer unit is preferably a carboxyl group-containing monomer unit.
In the acrylic rubber of the present invention, the Mooney viscosity is preferably in the range of 10 to 150.

Thus, according to the present invention, there is also provided a rubber composition comprising a rubber component containing the acrylic rubber and a crosslinking agent.
The rubber composition of the present invention preferably further comprises a crosslinking accelerator, an anti-aging agent, a filler, or a silane coupling agent.
Thus, according to the present invention, there is further provided a crosslinked rubber product obtained by crosslinking the rubber composition.

  According to the present invention, it is possible to effectively prevent the mutual adhesion of water-containing crumbs, to obtain a crosslinked rubber having a high polymer recovery rate, excellent dryability and roll processability, and excellent water resistance. An acrylic rubber manufacturing method is provided.

[Production method]
The method for producing an acrylic rubber of the present invention comprises an emulsion polymerization step in which a monomer mainly composed of (meth) acrylic acid ester is emulsion-polymerized using a polymerization catalyst to obtain an emulsion polymerization solution; In the presence of two or more types of polyoxyalkylene skeletons, particularly polyalkylene glycol (A) and polyalkylene glycol ester (B1) and / or polyalkylene glycol ether compound (B2). It is characterized by comprising a coagulation step for obtaining a hydrous crumb, a washing step for washing the hydrous crumb, and a drying step for drying the washed hydrous crumb.

<Monomer>
The monomer used in the present invention is (meth) acrylic acid ester [meaning acrylic acid ester and / or methacrylic acid ester. The same applies to methyl (meth) acrylate. ] As a main component. The (meth) acrylic acid ester as the main component is not particularly limited, and examples thereof include alkyl acrylates and alkoxyalkyl (meth) acrylates.

  As the (meth) acrylic acid alkyl ester, for example, an ester of an alkanol having 1 to 12 carbon atoms and (meth) acrylic acid is used, and an ester of an alkanol having 1 to 8 carbon atoms and (meth) acrylic acid is preferable. C2-C6 alkanols and (meth) acrylic acid esters are more preferred. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate , (Meth) acrylic acid n-hexyl, (meth) acrylic acid 2-ethylhexyl, (meth) acrylic acid cyclohexyl, and the like. Among these, ethyl (meth) acrylate and n-butyl (meth) acrylate are exemplified. Ethyl acrylate and n-butyl acrylate are particularly preferable.

  The (meth) acrylic acid alkoxyalkyl ester is preferably, for example, an ester of an alkoxyalkyl alcohol having 2 to 12 carbon atoms and (meth) acrylic acid, specifically, methoxymethyl (meth) acrylate, (meth) Ethoxymethyl acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-propoxyethyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, (meth) acrylic acid Examples include 3-methoxypropyl and 4-methoxybutyl (meth) acrylate. Among these, 2-ethoxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, and the like are preferable, and 2-ethoxyethyl acrylate and 2-methoxyethyl acrylate are more preferable.

  These (meth) acrylic acid esters can be used alone or in combination of two or more. The content of (meth) acrylic acid ester in the monomer is usually 50 to 99.9% by weight, preferably 60 to 99.7% by weight, more preferably 70 to 99.5% by weight. If the content of (meth) acrylic acid ester is excessively small, the weather resistance, heat resistance, and oil resistance of the resulting rubber cross-linked product may be reduced. On the other hand, if the content is excessively large, Heat resistance may be reduced. Moreover, as (meth) acrylic acid ester, it is preferable to use what consists of 30-100 weight% of (meth) acrylic-acid alkylester, and 70-0 weight% of (meth) acrylic-acid alkoxyalkylester.

  As the monomer in the emulsion polymerization step of the present invention, the improvement effect of the present invention is greatly preferred by including a crosslinkable monomer together with the (meth) acrylic acid ester.

  The crosslinkable monomer is not particularly limited, and examples thereof include a carboxyl group-containing monomer, an epoxy group-containing monomer, a halogen atom-containing monomer, and a diene monomer, preferably a carboxyl group Containing monomers, epoxy group-containing monomers, halogen atom-containing monomers, more preferably carboxyl group-containing monomers, highly improved compression set when acrylic rubber is crosslinked It is preferable.

  The carboxyl group-containing monomer is not particularly limited, but α, β-ethylenically unsaturated carboxylic acid can be preferably used. Examples of the α, β-ethylenically unsaturated carboxylic acid include α, β-ethylenically unsaturated monocarboxylic acid having 3 to 12 carbon atoms, α, β-ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms, Examples thereof include monoesters of α, β-ethylenically unsaturated dicarboxylic acids having 4 to 12 carbon atoms and alkanols having 1 to 8 carbon atoms. Use of α, β-ethylenically unsaturated carboxylic acid is preferable because it can further improve the compression set resistance when the resulting acrylic rubber is a rubber cross-linked product.

  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. 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 and chloromaleic acid. Examples of monoesters of α, β-ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms and alkanol having 1 to 8 carbon atoms include monomethyl fumarate, monoethyl fumarate, mono n-butyl fumarate, and maleic acid. Butenedionic acid mono-chain alkyl esters such as monomethyl, monoethyl maleate, mono-n-butyl maleate; monocyclopentyl fumarate, monocyclohexyl fumarate, monocyclohexenyl fumarate, monocyclopentyl maleate, monocyclohexyl maleate, maleic acid Butenedionic acid monoesters having an alicyclic structure such as monocyclohexenyl; itaconic acid monoesters such as monomethyl itaconate, monoethyl itaconate, mono n-butyl itaconate, monocyclohexyl itaconate;

  The carboxyl group-containing monomer is preferably an α, β-ethylenically unsaturated carboxylic acid, and a monoester of an α, β-ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms and an alkanol having 1 to 8 carbon atoms. Are more preferable, butenedionic acid mono-chain alkyl ester and butenedionic acid monoester having an alicyclic structure are particularly preferable. Specific preferred examples include mono n-butyl fumarate, mono n-butyl maleate, monocyclohexyl fumarate, monocyclohexyl maleate and the like, and mono n-butyl fumarate is particularly preferred. Among the above monomers, dicarboxylic acids include those that exist as anhydrides.

  The epoxy group-containing monomer is not particularly limited, and examples thereof include epoxy group-containing (meth) acrylate esters such as glycidyl (meth) acrylate; allyl glycidyl ether, vinyl glycidyl ether, and the like.

  The halogen atom-containing monomer is not particularly limited. For example, unsaturated alcohol esters of halogen-containing saturated carboxylic acids, (meth) acrylic acid haloalkyl esters, (meth) acrylic acid haloacyloxyalkyl esters, (meth) Examples include acrylic 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.

  Examples of the unsaturated alcohol ester of a halogen-containing saturated carboxylic acid include vinyl chloroacetate, vinyl 2-chloropropionate, and allyl chloroacetate. Examples of the (meth) acrylic acid haloalkyl ester include chloromethyl (meth) acrylate, 1-chloroethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 1,2-dichloroethyl (meth) acrylate, Examples thereof include 2-chloropropyl (meth) acrylate, 3-chloropropyl (meth) acrylate, 2,3-dichloropropyl (meth) acrylate, and the like. Examples of (meth) acrylic acid haloacyloxyalkyl esters include 2- (chloroacetoxy) ethyl (meth) acrylate, 2- (chloroacetoxy) propyl (meth) acrylate, and 3- (chloroacetoxy) (meth) acrylic acid. ) Propyl, 3- (hydroxychloroacetoxy) propyl (meth) acrylate, and the like. Examples of the (meth) acrylic acid (haloacetylcarbamoyloxy) alkyl ester include 2- (chloroacetylcarbamoyloxy) ethyl (meth) acrylate and 3- (chloroacetylcarbamoyloxy) propyl (meth) acrylate. It is done. 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. Examples of the halogen-containing unsaturated ketone include 2-chloroethyl vinyl ketone, 3-chloropropyl vinyl ketone, 2-chloroethyl allyl ketone, and the like. Examples of the halomethyl group-containing aromatic vinyl compound include p-chloromethylstyrene, m-chloromethylstyrene, o-chloromethylstyrene, and p-chloromethyl-α-methylstyrene. Examples of the halogen-containing unsaturated amide include N-chloromethyl (meth) acrylamide. Examples of the haloacetyl group-containing unsaturated monomer include 3- (hydroxychloroacetoxy) propyl allyl ether, p-vinylbenzyl chloroacetate, and the like.

  Examples of the diene monomer include conjugated dienes and non-conjugated dienes. Examples of the conjugated diene include 1,3-butadiene, isoprene, piperylene and the like. Non-conjugated dienes include, for example, ethylidene norbornene, dicyclopentadiene, dicyclopentadienyl (meth) acrylate, 2-dicyclopentadienyl ethyl (meth) acrylate, and the like.

  These crosslinkable monomers can be used alone or in combination of two or more. The content of the crosslinkable monomer in the monomer is usually 0.01 to 20% by weight, preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight. By making the content of the crosslinkable monomer within the above range, it is suitable for high recovery rate of rubber without causing kiln fouling in the polymerization tank during the production of acrylic rubber. And compression set resistance can be improved to a high degree.

  The monomer used for this invention can contain the other monomer which can be copolymerized as needed other than the said (meth) acrylic acid ester and a crosslinkable monomer. Other monomers that can be copolymerized are not particularly limited as long as they can be copolymerized, and examples thereof include aromatic vinyl monomers, α, β-ethylenically unsaturated nitrile monomers, and acrylamide monomers. And other olefinic monomers. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, divinylbenzene, and the like. Examples of the α, β-ethylenically unsaturated nitrile monomer include acrylonitrile and methacrylonitrile. Examples of acrylamide monomers include acrylamide and methacrylamide. Examples of 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.

  These other copolymerizable monomers can be used alone or in combination of two or more. The content of these other copolymerizable monomers in the monomer is usually 49.99% by weight or less, preferably 39.9% by weight or less, more preferably 29.5% by weight or less.

<Emulsion polymerization process>
The emulsion polymerization step in the production method of the present invention is characterized in that an emulsion polymerization solution is obtained by emulsion polymerization of the monomer using a polymerization catalyst.

  As an emulsion polymerization method, a conventional method may be followed. For example, a monomer having (meth) acrylic acid ester as a main component is preliminarily mixed with an emulsifier and water to prepare a monomer emulsion, and then polymerization is started. The emulsion polymerization can be carried out by adding an agent.

Although there is no special limitation as an emulsifier, For example, a nonionic emulsifier, an anionic emulsifier, a cationic emulsifier etc. can be mentioned.
Although it does not specifically limit as a nonionic emulsifier, For example, Polyoxyalkylene fatty acid esters, such as polyoxyethylene stearic acid ester and polyoxyethylene sorbitan alkyl ester; Polyoxyalkylene alkyl ethers, such as polyoxyethylene dodecyl ether; Polyoxyethylene Examples thereof include polyoxyalkylene alkyl phenyl ethers such as nonyl phenyl ether, polyoxyalkylene alkyl ethers and polyoxyalkylene alkyl phenyl ethers are preferred, and polyoxyethylene alkyl ethers and polyoxyethylene alkyl phenyl ethers are more preferred. These act as emulsifiers and also correspond to the above-mentioned polyalkylene glycol ester (B1) and / or polyalkylene glycol ether compound (B2). That is, by containing these compounds as nonionic emulsifiers, they can remain in the emulsion polymerization liquid obtained by polymerization, and therefore, at the time of coagulation, the polyalkylene glycol ester (B1) and / or poly As the ether compound (B2) of alkylene glycol, the coagulation operation can be performed in the state where it is present as it is. The weight average molecular weight (Mw) of the nonionic emulsifier is not particularly limited, but is usually 100 to 30,000, preferably 200 to 15,000, more preferably 300 to 10,000, and most preferably 400 to 8, 000 range.

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

  Examples of the cationic emulsifier include alkyltrimethylammonium chloride, dialkylammonium chloride, and benzylammonium chloride.

  These emulsifiers can be used alone or in combination of two or more. Among them, a nonionic emulsifier and an anionic emulsifier are preferable, and a nonionic emulsifier and an anionic emulsifier are more 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. It is possible to reduce the amount of coagulant used, and as a result, the amount of coagulant in the finally obtained acrylic rubber can be reduced, thereby improving the water resistance of the resulting rubber cross-linked product. it can. 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.

  The amount of the emulsifier used is the total amount of the emulsifier used relative to 100 parts by weight of the monomer used for the polymerization, and is usually 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, more preferably 1 to 3 parts by weight. Range. In addition, when the nonionic emulsifier and the anionic emulsifier are used in combination, the use ratio is usually 10/90 to 80/20, preferably 25/75 to 75/25, based on the weight ratio of the nonionic emulsifier / anionic emulsifier. More preferably, the range is 50/50 to 75/25, and most preferably 65/35 to 75/25, so that the object of the present application is highly enhanced.

  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 usually 0.001 to 5 parts by weight, preferably 0.01 to 1 part by weight, more preferably 0.05 to 0.5 parts by weight based on 100 parts by weight of the monomer used for the polymerization. The range is parts by weight.

  When a peroxide such as an organic peroxide and / or an inorganic peroxide is used as the polymerization initiator, it is preferably used as a redox polymerization initiator in combination with a reducing agent. Although it does not specifically limit as a reducing agent to combine, For example, a metal ion containing compound in a reduced state, such as ferrous sulfate, sodium hexamethylenediamine tetraacetate, cuprous naphthenate; Ascorbic acid, sodium ascorbate, ascorbine Ascorbic acid (salt) such as potassium acid; erythorbic acid (salt) such as erythorbic acid, sodium erythorbate, potassium erythorbate; saccharides; sulfinates such as sodium hydroxymethanesulfinate; sodium sulfite, potassium sulfite, sodium bisulfite Sodium aldehyde, sodium bisulfite, potassium bisulfite; pyrosulfites such as sodium pyrosulfite, potassium pyrosulfite, sodium pyrobisulfite, potassium hydrogenbisulfite; sodium thiosulfate, Thiosulfates such as potassium sulfate; phosphorous acid, sodium phosphite, potassium phosphite, sodium hydrogen phosphite, potassium hydrogen phosphite (salt); pyrophosphorous acid, sodium pyrophosphite, potassium pyrophosphite, pyro Examples include pyrophosphorous acid (salt) such as sodium hydrogen phosphite and potassium hydrogen phosphite; sodium formaldehyde sulfoxylate and the like.

  These reducing agents can be used singly or in combination of two or more, but a metal ion-containing compound in a reduced state as the first reducing agent and another reducing agent as the second reducing agent. Acrylic rubber obtained by combining, preferably combining ferrous sulfate and ascorbic acid (salt) and / or sodium formaldehyde sulfoxylate, particularly preferably combining ferrous sulfate and ascorbate It is preferable because water resistance and compression set can be enhanced to a high degree when the is used as a crosslinked product. The amount of the reducing agent used is preferably in the range of 0.00001 to 1 part by weight, more preferably 0.0001 to 0.5 part by weight, based on 100 parts by weight of the monomer used for the polymerization. When ferrous sulfate and ascorbic acid (salt) are used in combination, the amount of ferrous sulfate used is usually 0.00001 to 0.01 parts by weight with respect to 100 parts by weight of the monomer used for polymerization. The amount of ascorbic acid (salt) used is preferably in the range of 0.0001 to 0.001 parts by weight, and is usually in the range of 0.001 to 5 parts by weight, preferably 0.01 to 1 part by weight.

  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 polymerization.

  In 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 carry out the polymerization reaction while continuously dropping into the polymerization reaction system from the polymerization reaction start to an arbitrary time for all of the monomer, polymerization initiator, and reducing agent used for the polymerization. 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. In addition, superposition | polymerization is 0-70 degreeC normally, Preferably it is performed in the temperature range of 5-50 degreeC.

  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 obtain a monomer emulsion (preparation of emulsion). Step), it is preferable to continuously drop in the state of a monomer 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 and 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.

  The completion of emulsion polymerization can be performed by adding a polymerization terminator as necessary. Examples of the polymerization terminator include hydroxylamine, hydroxyamine sulfate, diethylhydroxyamine, hydroxyaminesulfonic acid and its alkali metal salt, sodium dimethyldithiocarbamate, hydroquinone and the like. Although the usage-amount of a polymerization terminator is not specifically limited, Preferably it is 0.1-2 weight part with respect to 100 weight part of monomers used for superposition | polymerization.

<Coagulation process>
The coagulation step in the production method of the present invention is characterized in that the emulsion polymerization liquid is coagulated in the presence of compounds having two or more polyoxyalkylene skeletons having different terminal structures to obtain a hydrous crumb.

  The compound having two or more polyoxyalkylene skeletons having different terminal structures is not particularly limited. For example, polyalkylene glycol (A) and polyalkylene glycol ester (B1) and / or polyalkylene glycol ether compound A combination with (B2) is preferred.

  The method of coagulating the emulsion polymerization solution obtained by the emulsion polymerization step is not particularly limited as long as it follows a conventional method, but can be carried out, for example, by contacting the emulsion polymerization solution and a coagulant. The method of bringing the emulsion polymerization solution and the coagulant into contact with each other for coagulation is not particularly limited. However, the coagulant is added to the emulsion polymerization solution or the coagulant is dissolved in water to obtain an aqueous solution. Examples thereof include a method of adding an emulsion polymerization solution to the aqueous solution of the agent.

  Further, the coagulation method is not particularly limited in the presence of the polyalkylene glycol (A) and the polyalkylene glycol ester (B1) and / or the polyalkylene glycol ether compound (B2). In the obtained emulsion polymerization liquid, polyalkylene glycol (A) and polyalkylene glycol ester (B1) and / or polyalkylene glycol ether compound (B2) are contained in advance, In addition, a method of adding a coagulant or by dissolving the coagulant in water to form an aqueous solution, and the polyalkylene glycol (A) and polyalkylene glycol ester (B1) and / or poly Alkylene glycol ether compound (B2) is contained, and In an aqueous solution of coagulant obtained by, and a method of adding a polymer emulsion. Alternatively, at least a part of the polyalkylene glycol (A) and the polyalkylene glycol ester (B1) and / or the polyalkylene glycol ether compound (B2) is previously contained in the emulsion polymerization liquid, and the polyalkylene glycol (A ) And the ester (B1) of polyalkylene glycol and / or the ether compound (B2) of polyalkylene glycol may be contained in an aqueous solution of a coagulant. Among these, the polyalkylene glycol (A) and the ester of polyalkylene glycol (B1) are preliminarily added to the emulsion polymerization liquid obtained by the emulsion polymerization step from the viewpoint that the effects of the present invention can be improved more appropriately. And / or an ether compound (B2) of polyalkylene glycol is preferably contained.

  In the present invention, the addition time of the polyalkylene glycol (A) is not particularly limited, and may be, for example, either a monomer emulsion before emulsion polymerization and / or an emulsion polymerization solution after emulsion polymerization. However, it is preferable to add to the emulsion polymerization liquid after emulsion polymerization.

  In the present invention, the addition time of the polyalkylene glycol ester (B1) and / or the polyalkylene glycol ether compound (B2) is not particularly limited. For example, the monomer emulsion before emulsion polymerization And / or a suitable result is obtained even if it adds to any of the emulsion polymerization liquid after emulsion polymerization.

  The polyalkylene glycol (A) is not particularly limited as long as it is a polymer of alkylene oxide having a polyoxyalkylene skeleton, but a polymer of lower alkylene oxide is preferably used. Specific examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, polyoxyethylene polyoxypropylene glycol, and the like. Among these, polyethylene glycol is preferable.

  The weight average molecular weight (Mw) of the polyalkylene glycol (A) is not particularly limited, but is usually 1,000 to 5,000,000, preferably 10,000 to 1,000,000, more preferably 50. In the range of 70,000 to 300,000.

  These polyalkylene glycols (A) can be used alone or in combination of two or more, and the addition amount is not particularly limited, but is 100 parts by weight of the acrylic rubber component in the emulsion polymerization liquid. On the other hand, it is usually in the range of 0.0001 to 1 part by weight, preferably 0.001 to 0.1, and more preferably 0.005 to 0.05 part by weight.

The polyalkylene glycol ester (B1) and / or the polyalkylene glycol ether compound (B2) is not particularly limited as long as it is a polyalkylene glycol ester compound, an ether compound, or an ester and ether compound. At least one polyoxyalkylene ester compound selected from the group consisting of polyoxyalkylene phosphate ester, polyoxyalkylene sulfate ester, polyoxyalkylene fatty acid ester and other polyoxyalkylene ether ester, and / or polyoxyalkylene alkyl ether And a polyoxyalkylene ether compound having no at least one ester group selected from the group consisting of polyoxyalkylene aryl ethers is preferably used.
As the polyoxyalkylene ester compound, polyoxyalkylene phosphate ester and polyoxyalkylene fatty acid ester are particularly preferable.

  Examples of the polyoxyalkylene phosphoric acid ester include polyoxyethylene stearyl ether phosphoric acid, polyoxyethylene lauryl ether phosphoric acid, polyoxyethylene oleyl ether phosphoric acid, polyoxyethylene tridecyl ether phosphoric acid and the like.

  Examples of polyoxyalkylene fatty acid esters include polyoxyethylene monostearate, polyoxyethylene monolaurate, polyoxyethylene monooleate, polyoxyethylene sorbitan laurate, polyoxyethylene sorbitan stearate, polyoxyethylene Examples include sorbitan oleate and polyoxyethylene sorbitan palmitate. Among these, polyoxyethylene monostearate is preferable.

  Examples of the polyoxyalkylene alkyl ether include polyoxyethylene dodecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene myristyl ether, polyoxyethylene octyl Examples include dodecyl ether, polyoxyethylene polyoxypropylene cetyl ether, and polyoxyethylene polyoxypropylene decyl tetradecyl ether. Among these, polyoxyethylene dodecyl ether is preferable.

  Examples of the polyoxyalkylene aryl ether include polyoxyethylene nonyl phenyl ether and polyoxyethylene octyl phenyl ether. Among these, polyoxyethylene nonylphenyl ether is preferable. The weight average molecular weight (Mw) of the polyalkylene glycol ester (B1) and / or the polyalkylene glycol ether compound (B2) is not particularly limited, but is usually 100 to 30,000, preferably 200 to 15,000. More preferably, it is in the range of 300 to 10,000, most preferably 400 to 8,000.

  These ester (B1) of polyalkylene glycol and / or ether compound (B2) of polyalkylene glycol can be used alone or in combination of two or more, and the addition amount depends on the purpose of use. Although appropriately selected, it is usually 0.01 to 15 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the acrylic rubber component in the emulsion polymerization liquid. Range.

  The ratio of the polyalkylene glycol (A) to the polyalkylene glycol ester (B1) and / or the polyalkylene glycol ether compound (B2) is not particularly limited, but the polyalkylene glycol (A) / polyalkylene glycol The weight ratio of the ester (B1) and / or the polyalkylene glycol ether compound (B2) is usually 30/70 to 99.9999 / 0.0001, preferably 50/50 to 99.999 / 0.001, more preferably. Is in the range of 70/30 to 99.99 / 0.01, more preferably 80/20 to 99.95 / 0.05, most preferably 90/10 to 99.9 / 0.1.

  Although it does not specifically limit as a coagulant, For example, a 1-3 valent metal salt is mentioned. The 1 to 3 metal salt is a salt containing a metal that becomes a 1 to 3 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 1 to 3 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; Metal 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; sulfuric acid And metal sulfates such as sodium, 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, metal chlorides, metal sulfates and the like are preferable, monovalent or divalent metal chlorides, monovalent or divalent metal sulfates are more preferable, and monovalent or divalent metal sulfates are particularly preferable. As the monovalent or divalent metal salt, calcium chloride, sodium chloride, magnesium sulfate and sodium sulfate are preferable, and magnesium sulfate and sodium sulfate are more preferable. Among these, when a sulfate, preferably a metal sulfate, more preferably a monovalent or divalent metal sulfate is used, the effect of the present invention is highly enhanced, which is preferable.

  These coagulants can be used alone or in combination of two or more. The amount of coagulant used (containing) is usually 0.01 to 100 parts by weight, preferably 0.1 to 50 parts by weight, more preferably 1 to 30 parts per 100 parts by weight of the acrylic rubber component in the emulsion polymerization liquid. The range is parts by weight. When the coagulant is in this range, it is preferable because the compression set and the water resistance when the acrylic rubber is crosslinked can be improved to a high degree while sufficiently solidifying the acrylic rubber.

  The method of bringing the emulsion polymerization solution into contact with the coagulant may be in accordance with a conventional method, and may be carried out by adding a coagulant to the emulsion polymerization solution or charging the emulsion polymerization solution into the coagulant solution. When the emulsion polymerization solution is added, an aqueous solution is usually used, and the concentration of the coagulant is appropriately selected and is usually 1 to 40% by weight, preferably 5 to 30% by weight, more preferably 10 to 25% by weight. % Range. In addition, when adding a coagulant to the emulsion polymerization liquid, the coagulant may be a powdered solid or may be added after being dissolved as an aqueous solution. The concentration in the case of adding the coagulant as an aqueous solution is appropriately selected according to the purpose of use, and is usually 1 to 50% by weight, preferably 5 to 40% by weight, more preferably 10 to 30% by weight.

  When the coagulant is used, the coagulation temperature of the emulsion polymerization liquid is a temperature at which the emulsion polymerization liquid and the coagulant are in contact with each other. Preferably it is the range of 78-90 degreeC. The compound having a polyoxyalkylene skeleton changes in polymer structure depending on the temperature and greatly affects the coagulation reaction. Therefore, the coagulation (contact) temperature is preferably within this range.

<Washing process>
The washing step in the production method of the present invention is to wash the water-containing crumb obtained in the coagulation step.

  Although it does not specifically limit as a washing | cleaning method, The method of using water as a washing | cleaning liquid and performing water washing by mixing the added water with a water-containing crumb is mentioned. Although it does not specifically limit as temperature at the time of water washing, Preferably it is 5-60 degreeC, More preferably, it is 10-50 degreeC, and mixing time is 1-60 minutes, More preferably, it is 2-30 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 with respect to 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. However, it is preferably performed a plurality of times from the viewpoint of reducing the residual amount of the coagulant in the finally obtained acrylic rubber, and preferably 2 to 10 times. More preferably, it is 3 to 8 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, but even if the washing exceeds the above range, the coagulant removing effect is effective. 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.

  Moreover, in this invention, after performing water washing, you may perform the acid washing | cleaning which uses an acid as a washing | cleaning liquid further. By carrying out the acid cleaning, the storage stability of the acrylic rubber can be enhanced to a high level, and the compression set resistance in the case of a rubber cross-linked product can also be improved.

  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 the hydrous crumb in acid washing, it is preferably added in the form of an aqueous solution, and the pH is usually 6 or less, preferably 5 or less, more preferably 4 or less, and most preferably 3 or less. Yes, the lower limit of pH is not particularly limited, but is usually 1 or more. When the acid concentration is within this range, the effect of improving storage stability and compression set is maximized. The pH at that time is usually 6 or less, preferably 5 or less, more preferably 4 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.

Moreover, it is although it does not specifically limit as temperature at the time of acid washing, Preferably it is 5-60 degreeC, More preferably, it is 10-50 degreeC, and mixing time is 1-60 minutes, More preferably, it is 2-30 minutes.
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 drying step of the present invention, the water-containing crumb that has been washed in the washing step is dried.

  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, it is set to -170 degreeC.

[Acrylic rubber]
The acrylic rubber of the present invention thus obtained can effectively prevent the mutual adhesion of water-containing crumbs, has a high polymer recovery rate, is excellent in roll processability, and has an excellent water resistance. give.

  The acrylic rubber of the present invention is not particularly limited except that it mainly comprises a (meth) acrylic acid ester unit, but is excellent in water resistance and compression set resistance when it further contains a crosslinkable monomer unit. It is.

  The monomer composition in the acrylic rubber of the present invention is appropriately selected according to the purpose of use, but the (meth) acrylic acid ester unit is usually 50 to 99.9% by weight, preferably 60 to 99.7% by weight. %, More preferably 70-99.5% by weight, and the content of the crosslinkable monomer is usually 0.01-20% by weight, preferably 0.1-10% by weight, more preferably 0.5%. The content of the other copolymerizable monomer is generally 0 to 49.99% by weight, preferably 0 to 39.9% by weight, more preferably 0 to 29.5% by weight. It is. Examples of the (meth) acrylic acid ester, the crosslinkable monomer, and the other copolymerizable monomer are the same as those in <Monomer>. Examples of the crosslinkable monomer unit include a carboxyl group-containing monomer unit, a halogen group-containing monomer unit, and an epoxy group-containing monomer unit, and a carboxyl group-containing monomer unit is particularly preferable.

  The Mooney viscosity (ML1 + 4, 100 ° C.) of the acrylic rubber of the present invention is selected according to the purpose of use, but is usually in the range of 10 to 150, preferably 20 to 100, more preferably 25 to 60.

  The glass transition temperature (Tg) of the acrylic rubber of the present invention is selected according to the purpose of use, but is usually 15 ° C. or lower, preferably 0 ° C. or lower.

  According to this invention, the manufacturing method of the said acrylic rubber and the acrylic rubber obtained by this manufacturing method are provided.

  In particular, according to the acrylic rubber of the present invention obtained by the above-described production method, in addition to excellent roll processability and water resistance, generation of mutual adhesion of water-containing crumbs is effectively prevented. Here, in the field of rubber such as acrylic rubber, it is normal to coagulate when obtaining a solid rubber from a solution or dispersion of a rubber obtained by polymerization. Rubber such as acrylic rubber will be obtained in the form of hydrous crumb. On the other hand, according to the present invention, it is possible to provide an acrylic rubber in which the occurrence of mutual adhesion in the form of such a hydrous crumb is effectively prevented.

  As described above, since the hydrated crumb is obtained by solidification, the presence or absence of mutual adhesion of the hydrated crumb is greatly influenced by the solidification conditions and the state at the time of solidification. In the acrylic rubber of the present invention, such coagulation is carried out in the presence of a compound having two or more types of polyoxyalkylene skeletons having different terminal structures, specifically, polyalkylene glycol (A) and polyalkylene glycol. It is obtained by coagulation in the presence of an ester (B1) and / or an ether compound (B2) of polyalkylene glycol. Here, the acrylic rubber obtained by such coagulation includes compounds having two or more types of polyoxyalkylene skeletons having different terminal structures, specifically, polyalkylene glycol (A) and polyalkylene glycol ester (B1 ) And / or a polyalkylene glycol ether compound (B2) and a coagulant, but according to the knowledge of the present inventors, the compound and coagulant having two or more polyoxyalkylene skeletons are simply The inclusion of such an adhesion cannot prevent the occurrence of such mutual adhesion. Specifically, in the presence of a compound having two or more polyoxyalkylene skeletons having different terminal structures during solidification, Alkylene glycol (A) and polyalkylene glycol ester (B1) and / or polyalkylene glycol In the presence of a call ether compound (B2), it has been found that it is necessary the work was performed using a metal sulfate as a coagulant. The acrylic rubber of the present invention is obtained for the first time through such a coagulation method, and is simply a compound having two or more polyoxyalkylene skeletons having different terminal structures, specifically, a polyalkylene glycol ( A) and an ester (B1) of polyalkylene glycol and / or an ether compound (B2) of polyalkylene glycol and a coagulant cannot be specified.

  Even if the internal state of the acrylic rubber of the present invention is analyzed by various analytical instruments, the acrylic rubber and the compound having two or more polyoxyalkylene skeletons having different terminal structures (specifically, The polyalkylene glycol (A) and the polyalkylene glycol ester (B1) and / or the polyalkylene glycol ether compound (B2)) both have carbon atoms and oxygen atoms as the main components, and their dispersion It is extremely difficult to specify the state and the like. Therefore, it can be said that it is sufficiently rational to specify the acrylic rubber of the present invention by the production method.

[Rubber composition]
The rubber composition of the present invention comprises a rubber component containing the acrylic rubber and a crosslinking agent. The content of the acrylic rubber of the present invention in the rubber component may be selected according to the purpose of use. For example, it is usually 30% by weight or more, preferably 50% by weight or more, more preferably 70% by weight or more.

  As the rubber component, the above acrylic rubber can be used alone or in combination with the above acrylic rubber and other rubbers.

  Other rubbers include acrylic rubbers 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, olefin elastomer, styrene elastomer, Examples include vinyl chloride elastomers, polyester elastomers, polyamide elastomers, polyurethane elastomers, polysiloxane elastomers, and the like.

  These other rubbers can be used alone or in combination of two or more. The content of other rubbers in the rubber component is appropriately selected within a range not impairing the effects of the present invention, and is usually 70% by weight or less, preferably 50% by weight or less, and more preferably 30% by weight or less.

  Although it does not specifically limit as a crosslinking agent used for the rubber composition of this invention, For example, polyvalent amine compounds, such as a diamine compound, and its carbonate; Sulfur compound; Sulfur donor; Multivalent epoxy compound; Conventionally known crosslinking agents such as carboxylic acid ammonium salts; organic peroxides; polyvalent carboxylic acids; isocyanuric acid compounds; organic peroxides; triazine compounds; Among these, polyvalent amine compounds and triazine compounds are preferable, and polyvalent amine compounds are particularly preferable.

  Examples of the polyvalent amine compound include aliphatic polyvalent amine compounds such as hexamethylene diamine, hexamethylene diamine carbamate, and N, N′-dicinnamylidene-1,6-hexanediamine; 4,4′-methylene dianiline, p. -Phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4 '-(m-phenylenediisopropylidene) dianiline, 4,4'-(p-phenylenediene) Isopropylidene) dianiline, 2,2′-bis [4- (4-aminophenoxy) phenyl] propane, 4,4′-diaminobenzanilide, 4,4′-bis (4-aminophenoxy) biphenyl, m-xyl Range amine, p-xylylene diamine, 1,3,5-benzenetri Aromatic polyvalent amine compounds such as amine; and the like. Among these, hexamethylenediamine carbamate, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane and the like are preferable. These polyvalent amine compounds are particularly preferably used in combination with a carboxyl group-containing acrylic rubber.

  Examples of the triazine compound include 6-trimercapto-s-triazine, 2-anilino-4,6-dithiol-s-triazine, 1-dibutylamino-3,5-dimercaptotriazine, 2-dibutylamino-4, 6-dithiol-s-triazine, 1-phenylamino-3,5-dimercaptotriazine, 2,4,6-trimercapto-1,3,5-triazine, 1-hexylamino-3,5-dimercaptotriazine Etc. These triazine compounds are particularly preferably used in combination with a halogen group-containing acrylic rubber.

  These crosslinking agents can be used alone or in combination of two or more, and the blending amount is usually 0.001 to 20 parts by weight, preferably 0.1 to 100 parts by weight with respect to 100 parts by weight of the rubber component. 10 parts by weight, more preferably 0.1 to 5 parts by weight. By setting the blending amount of the cross-linking agent within this range, it is preferable that the mechanical strength as a rubber cross-linked product can be made excellent while the rubber elasticity is sufficient.

  The rubber composition of the present invention is suitable for further improving the effects of the present invention by further blending a crosslinking accelerator. Although it does not specifically limit as a crosslinking accelerator, For example, a guanidine type crosslinking accelerator, a diazabicycloalkene type crosslinking accelerator, an aliphatic secondary amine type crosslinking accelerator, an aliphatic tertiary amine type crosslinking accelerator, dithiocarbamic acid Suitable examples include salt-based vulcanization accelerators. Among these, guanidine-based crosslinking accelerators and dithiocarbamate-based crosslinking accelerators are particularly preferable, and guanidine-based crosslinking accelerators are more preferable.

  Specific examples of the guanidine crosslinking accelerator include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, and di-o-tolylguanidine salt of dicatechol borate. 1,3-di-o-cumenyl guanidine, 1,3-di-o-biphenyl guanidine, 1,3-di-o-cumenyl-2-propionyl guanidine, and the like may be mentioned, 1,3-diphenyl guanidine, 1,3-di-o-tolylguanidine and 1-o-tolylbiguanide are preferred because of their high reactivity, and 1,3-diphenylguanidine (DPG) is particularly preferred because of their higher reactivity.

  Specific examples of the diazabicycloalkene-based crosslinking accelerator include 1,8-diazabicyclo [5.4.0] unde-7-cene, 1,5-diazabicyclo [4.3.0] no-5-ene, and the like. Can be mentioned.

  Examples of the aliphatic secondary amine crosslinking accelerator 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. .

  Examples of the aliphatic tertiary amine crosslinking accelerator include trimethylamine, triethylamine, tripropylamine, triallylamine, triisopropylamine, tri-n-butylamine, tri-t-butylamine, tri-sec-butylamine, and trihexylamine. , Triheptylamine, trioctylamine, trinonylamine, tridecylamine, triundecylamine, tridodecylamine and the like.

  Specific examples of the dithiocarbamate crosslinking accelerator include zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc dipentyldithiocarbamate, zinc dihexyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, N-ethyl- Zinc N-phenyldithiocarbamate, zinc dibenzyldithiocarbamate, copper dipropyldithiocarbamate, copper diisopropyldithiocarbamate, copper dibutyldithiocarbamate, sodium diethyldithiocarbamate, sodium diisopropyldithiocarbamate, sodium dibutyldithiocarbamate, ferric dimethyldithiocarbamate And ferric diethyldithiocarbamate. Among these, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc dibenzyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate and the like are preferable.

  As the crosslinking accelerator used in the present invention, other crosslinking accelerators other than the above can be used. Examples of other crosslinking accelerators include N-cyclohexyl-2-benzothiazylsulfenamide, N-tert-butyl-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N.I. Sulfenamide-based crosslinking accelerators such as N-diisopropyl-2-benzothiazole sulfenamide; Thiourea-based crosslinking accelerators such as diethylthiourea; 2-mercaptobenzothiazole, dibenzothiazyl disulfide, 2-mercaptobenzothiazole zinc salt, etc. Thiazole-based crosslinking accelerators; xanthogenic acid-based crosslinking accelerators such as sodium isopropylxanthate, zinc isopropylxanthate, and zinc butylxanthate; thiuram-based crosslinking accelerators such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; Imidazole-based cross-linking accelerators such as methylimidazole and 2-phenylimidazole; tetra n-butylammonium bromide, octadecyltri n-butylammonium bromide, etc. Quaternary onium salt-based crosslinking accelerator; triphenylphosphine, tertiary phosphine crosslinking accelerators such as tri -p- tolylphosphine; and the like.

  These crosslinking accelerators can be used alone or in combination of two or more, and the blending amount is usually 0.01 to 20 parts by weight, preferably 0. 1 to 10 parts by weight, more preferably 1 to 5 parts by weight. When the content of the crosslinking accelerator is within this range, it is preferable because the tensile strength and compression set resistance of the resulting rubber crosslinked product can be further improved.

  The rubber composition of the present invention is suitable for further improving the cross-linking properties by further blending a scorch inhibitor. The scorch inhibitor is not particularly limited, but examples thereof include imide compounds such as N-cyclohexylthiophthalimide, alkylamine alkylphenol compounds, hydroquinone / quinone compounds, 2,4-di (3-isopropylphenyl) -4-methyl. -1-pentene can be mentioned, and an imide compound is preferable.

  These scorch preventing agents can be used alone or in combination of two or more, and the blending amount thereof is 0.01 to 5 parts by weight, preferably 0.05 with respect to 100 parts by weight of the rubber component. It is -1 weight part, More preferably, it is the range of 0.1-0.5 weight part.

  The rubber composition of the present invention preferably further contains an antioxidant. The anti-aging 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-tert-butylfunol), 2,2′-methylene-bis (4-methyl-6-tert-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 products; 2,4-bis [(octylthio) methyl] -6-methylphenol, 2,2′-thiobis- (4-methyl-6-tert-butylphenol) 4,4′-thiobis- (6-tert-butyl-o-cresol), 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazine- Thiophenol-based antioxidants such as 2-ylamino) phenol; phosphite-based antioxidants such as tris (nonylphenyl) phosphite, diphenylisodecyl phosphite, tetraphenyldipropylene glycol diphosphite; dilauryl thiodipropionate Sulfur ester type antioxidants such as phenyl-α-naphthylamine, phenyl-β-naphthylamine, p- (p- Toluenesulfonylamido) -diphenylamine, 4,4 ′-(α, α-dimethylbenzyl) diphenylamine, N, N-diphenyl-p-phenylenediamine, N-isopropyl-N′-phenyl-p-phenylenediamine, butyraldehyde Amine-based antioxidants such as aniline condensates; imidazole-based antioxidants such as 2-mercaptobenzimidazole; quinoline-based antioxidants such as 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline; And hydroquinone anti-aging agents such as 2,5-di- (t-amyl) hydroquinone.

  These anti-aging agents can be used alone or in combination of two or more, and the blending amount thereof is 0.01 to 15 parts by weight, preferably 0.1 to 100 parts by weight of the rubber component. The range is from 10 to 10 parts by weight, more preferably from 1 to 5 parts by weight.

  As the rubber composition of the present invention, a rubber composition further containing a filler can be suitably used. Although there is no special limitation as a filler, For example, a reinforcing filler, a non-reinforcing filler, etc. are mentioned, Preferably it is a reinforcing filler.

  Examples of the reinforcing filler include carbon black such as furnace black, acetylene black, thermal black, channel black, and graphite; silica such as wet silica, dry silica, and colloidal silica. Non-reinforcing fillers include quartz powder, diatomaceous earth, zinc white, basic magnesium carbonate, activated calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, aluminum sulfate, calcium sulfate, and barium sulfate. be able to.

  These fillers can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range not impairing the effects of the present invention, and is usually based on 100 parts by weight of the rubber component. It is 1 to 200 parts by weight, preferably 10 to 150 parts by weight, more preferably 20 to 100 parts by weight.

  As the rubber composition of the present invention, a rubber composition further blended with a silane coupling agent can be suitably used. The silane coupling agent that can be used is not particularly limited. For example, 3-methacryloxypropyltrimethoxysilane, bis (3- (triethoxysilyl) propyl) disulfide, bis (3-triethoxysilylpropyl) tri Sulfide, bis (3- (triethoxysilyl) propyl) tetrasulfide, γ-mercaptopropyltriethoxysilane, 3- [ethoxybis (3,6,9,12,15-pentaoxaoctacosan-1-yloxy) silyl] -1-propanethiol, 3-octanoylthio-1-propyl-triethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, γ-trimethoxysilylpropylbenzothiazyl tetrasulfide, 3-tri Methoxysilyl Propylbenzothiazole tetrasulfide, 3-thiocyanate propyltriethoxysilane, vinyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, 3-trimethoxysilylpropyl methacrylate monosulfide, γ-glycol Examples include cidoxypropyltriethoxysilane, 3-nitropropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.

  These silane coupling agents can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected according to the purpose of use, and is usually 0. The range is 01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, and more preferably 0.5 to 3 parts by weight.

  The rubber composition of the present invention may contain other compounding agents other than the above crosslinking agent, crosslinking accelerator, scorch inhibitor, filler and silane coupling agent. Other compounding agents include, for example, dispersants such as higher fatty acids and their metal amine salts, plasticizers such as phthalic acid derivatives, adipic acid derivatives and sebacic acid derivatives, lubricating oils, process oils, coal tar, castor oil, Softener such as calcium stearate, anti-aging agent, light stabilizer, processing aid, adhesive, lubricant, flame retardant, anti-mold agent, antistatic agent, colorant, crosslinking retarder, polyolefin resin, polystyrene resin, Examples include polyacrylic resins, polyphenylene ether resins, polyester resins, polycarbonate resins, polyamide resins, vinyl chloride resins, and fluororesins. These other compounding agents can be used alone or in combination of two or more, and the compounding amount is appropriately selected within a range not impairing the effects of the present invention.

  As a blending method of the rubber composition of the present invention, Niino means conventionally used in the polymer processing field, for example, an open roll, a Banbury mixer, various kneaders, and the like can be used.

  The blending procedure may be a normal procedure performed in the field of polymer processing, for example, a component that is not easily reacted or decomposed by heat and then easily reacted or decomposed by heat. It is preferable to mix a crosslinking agent or the like in a short time at a temperature at which no reaction or decomposition occurs.

[Rubber cross-linked product]
The rubber cross-linked product of the present invention is obtained by cross-linking the rubber composition.
The rubber cross-linked product of the present invention uses the rubber composition of the present invention and 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 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 150 ° C. The crosslinking temperature is usually 100 to 250 ° C., preferably 130 to 220 ° C., more preferably 150 to 200 ° C., and the crosslinking time is usually 0.1 minutes to 10 hours, preferably 1 minute 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.

  The rubber cross-linked product of the present invention may be further heated and subjected to secondary cross-linking depending on the shape and size of the rubber cross-linked product. 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. Although the compression set measured according to JIS K6262 of the crosslinked product of the present invention is appropriately selected according to the purpose of use, it is usually 1 to 50%, preferably 5 to 25%, more preferably 8 to. The range is 20%.
The rubber cross-linked product of the present invention makes use of the above characteristics, for example, O-rings, packings, diaphragms, oil seals, shaft seals, bearing seals, mechanical seals, well head seals, electrical / electronic equipment seals, air compression equipment. Seal material such as a seal for seals; rocker cover gasket attached to the connecting part between the cylinder block and the cylinder head, oil pan gasket attached to the connecting part between the oil pan and the cylinder head or transmission case, positive electrode, electrolyte plate and negative electrode Various gaskets such as gaskets for fuel cell separators and gaskets for top covers of hard disk drives mounted between a pair of housings sandwiching a unit cell equipped with shock absorbers, anti-vibration materials, wire covering materials, industrial belts, tubes・ Hose; sheet ; Is preferably used as such.

  The rubber cross-linked product of the present invention is also used as an extrusion mold product and a mold cross-linked product used in automobile applications, for example, fuel oil around a fuel tank such as a fuel hose, filler neck hose, vent hose, paper hose, oil hose, etc. It is suitably used for various hoses such as air hoses such as system hoses, turbo air hoses and emission control hoses, radiator hoses, heater hoses, brake hoses and air conditioner hoses.

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.

[Glass transition temperature (Tg)]
The glass transition temperature (Tg) of the acrylic rubber was measured according to JIS K6240.

[Interchangeability of water-containing crumbs after washing]
15 g of water-containing crumb after washing was put into a cylinder having an inner diameter of 10 mm and compressed at 1 MPa for 30 seconds to adhere the crumb particles to form a cylindrical molded body. And the obtained cylindrical molded object was suspended by pinching | interposing between clips, and time until at least one part of crumb particle | grains which comprise a cylindrical molded object fell was measured as fall time. It can be determined that the shorter the falling time is, the lower the mutual adhesion of the hydrated crumbs after washing is.

[Moisture content of acrylic rubber after drying]
The dried acrylic rubber was placed on an aluminum dish, dried in an oven at 100 ° C. for 1 hour, and the moisture content of the dried acrylic rubber was determined from the weight of the acrylic rubber before and after drying according to the following formula. .
Water content (% by weight) of acrylic rubber after drying = [(weight before performing drying operation for time (g) -1 weight after performing drying operation for 1 hour (g)) ÷ drying operation for 1 hour Weight before performing (g)] × 100

[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.

[Probe tack test]
For the acrylic rubber composition (1), a probe tack test was performed using a tacking tester (TAC-1000: manufactured by Reska Corporation). Specifically, with respect to an acrylic rubber sample molded to 30 mm × 20 mm × 2 mm, a SUS probe (10 mmφ) was pressed under the conditions of a pressing speed of 0.05 mm / s, a pressing load: 20 gf, and a pressing holding time of 10 seconds. A tacking operation (N) was measured when the SUS probe was pulled up at a lifting speed of 15 mm / s. The lower the tack strength, the better the productivity without sticking to the dryer, etc. (The higher the tack strength, the harder it will start to stick to the dryer walls and conveyors, etc., the production efficiency will be reduced and evenly uniform. This also causes problems such as inability to obtain quality). Moreover, it can be judged that the lower the tack strength, the lower the adhesiveness to the roll when processed with a roll, and the better the roll processability.

[water resistant]
The acrylic rubber composition (2) is put into a mold having a length of 15 cm, a width of 15 cm, and a depth of 0.2 cm, and is first crosslinked by pressing at 170 ° C. for 20 minutes while being pressed at a press pressure of 10 MPa, 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 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 test piece after immersion−Volume of test piece before immersion) ÷ Volume of test piece before immersion × 100

[Example 1]
[Acrylic rubber polymerization]
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 0.567 parts of sodium lauryl sulfate (trade name “Emar 2FG”, manufactured by Kao Co., Ltd.) and polyoxyethylene dodecyl ether (trade name “Emulgen 105”, weight average) A monomer emulsion was obtained by charging 1.4 parts of molecular weight (Mw) = about 1500, manufactured by Kao Corporation and stirring.

  Subsequently, 1700.853 parts of pure water and 2.97 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, 145.29 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.

[Coagulation / isolation of acrylic rubber]
And with respect to 100 parts of emulsion polymerization liquid obtained by superposition | polymerization, stearyl 3- (3,5-di-tert- butyl-4-hydroxyphenyl) propionate (brand name "Irganox 1076", BASF) as an anti-aging agent Manufactured by the company) 0.3 parts (total of the monomers used in the production of the emulsion polymerization solution (ie, ethyl acrylate, n-butyl acrylate, mono n-butyl fumarate) 100 parts 1 part), polyethylene glycol as polyalkylene glycol (A) (weight average molecular weight (Mw) = 100,000, weight average molecular weight measured using GPC in DMF solvent containing 10 mmol LiBr.) 011 parts (0.039 parts relative to a total of 100 parts of the charged monomers used in the production of the emulsion polymerization liquid), and polyalkylene glycol 0.075 part of polyoxyethylene stearyl ether phosphate (trade name “phosphanol RL-210”, weight average molecular weight (Mw) = about 500, manufactured by Toho Chemical Industry Co., Ltd.) as an ester (B1) A mixed solution was obtained by mixing 0.25 parts) with respect to a total of 100 parts of the charged monomers used in producing the polymerization solution. 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 solidify the polymer, and then filtered to remove acrylic. A water-containing crumb of rubber (A1) was obtained.

[Cleaning and drying of acrylic rubber]
Next, 388 parts of industrial water was added to 100 parts of the solid content of the hydrated crumb obtained above, and after stirring for 5 minutes at room temperature in the coagulation tank, the water content was discharged from the coagulation tank. The 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 388 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 for 5 minutes at room temperature, 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, 388 parts of pure water is added to 100 parts of solid content of the water-containing crumb subjected to pickling, and after stirring for 5 minutes at room temperature in the coagulation tank, the water is discharged from the coagulation tank, so that the water-containing crumb is discharged. Was washed with pure water. And about the water-containing crumb after washing | cleaning, according to the said method, the mutual attachment property of the water-containing crumb after washing | cleaning was measured. The results are shown in Table 1.
Next, the washed hydrated crumb was dried at 110 ° C. for 1 hour with a hot air dryer to obtain a solid acrylic rubber (A1), the polymer moisture content was measured, and the results are shown in Table 1. It was.

[Characteristic evaluation of acrylic rubber]
The resulting acrylic rubber (A1) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the acrylic rubber (A1) has a glass transition temperature (Tg) of −30 ° C., and the recovery rate of the acrylic rubber (A1) is 100%. The composition of the acrylic rubber (A1) was 49.3% by weight of ethyl acrylate units, 49.3% by weight of n-butyl acrylate units, and 1.4% by weight of mono n-butyl fumarate units.

[Production of Acrylic Rubber Composition (1)]
Using a Banbury mixer, 100 parts of the resulting acrylic rubber (A1), 60 parts of carbon black (trade name “Seast SO”, manufactured by Tokai Carbon Co., Ltd.), 2 parts of stearic acid, and 4, 4′-bis (α , α-dimethylbenzyl) diphenylamine (trade name “NOCRACK CD”, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 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 -An acrylic rubber composition (1) was obtained by blending and kneading 2 parts of di-o-tolylguanidine (trade name “Noxeller DT”, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., crosslinking accelerator). And the probe tack test was done according to the said method using the obtained acrylic rubber composition (1). The results are shown in Table 1.

[Production of acrylic rubber composition (2)]
Using a Banbury mixer, 100 parts of acrylic rubber (A1), 30 parts of clay (trade name “Satinton Clay 5A”, Takehara Kagaku Kogyo Co., Ltd., calcined kaolin), silica (trade name “Carplex 1120”, Evonik) 15 parts, silica (trade name “Carplex 67”, manufactured by Evonik) 35 parts, stearic acid 2 parts, ester wax (trade name “Greg G-8205”, manufactured by Dainippon Ink & Chemicals) 1 part, 2,4′-bis (α, α-dimethylbenzyl) diphenylamine (trade name “NOCRACK CD”, manufactured by Ouchi Shinsei Chemical Co., Ltd.) and 3-methacryloxypropyltrimethoxysilane (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 -An acrylic rubber composition (2) was obtained by blending and kneading 2 parts of di-o-tolylguanidine (trade name “Noxeller DT”, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., crosslinking accelerator). Then, using the obtained acrylic rubber composition (2), water resistance was evaluated according to the above method. The results are shown in Table 1.

[Example 2]
Instead of polyoxyethylene dodecyl ether, polyoxyethylene nonylphenyl ether (trade name “Neugen EA70”, receiving average molecular weight ( Mw) = 600, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) A monomer emulsion was obtained in the same manner as in Example 1, except that 1.4 parts were used. Next, using the obtained monomer emulsion, emulsion polymerization was performed in the same manner as in Example 1 to obtain an emulsion polymerization solution.
Next, using the emulsion polymerization solution obtained above, in the same manner as in Example 1, a mixed solution was prepared and a coagulation operation was performed to obtain a water-containing crumb of acrylic rubber (A2). Further, the water-containing crumb of the acrylic rubber (A2) was washed four times with water, pickling and pure water in the same manner as in Example 1. And about the water-containing crumb after washing | cleaning, according to the said method, the mutual attachment property of the water-containing crumb after washing | cleaning was measured. The results are shown in Table 1.

Next, the washed hydrated crumb was dried at 110 ° C. for 1 hour with a hot air dryer to obtain a solid acrylic rubber (A2), the polymer moisture content was measured, and the results are shown in Table 1. It was.
The resulting acrylic rubber (A2) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the acrylic rubber (A2) has a glass transition temperature (Tg) of −30 ° C., and the recovery rate of the acrylic rubber (A2) is 100%. The composition of the acrylic rubber (A2) was 49.3% by weight of ethyl acrylate units, 49.3% by weight of n-butyl acrylate units, and 1.4% by weight of mono n-butyl fumarate units.
An acrylic rubber composition (1) and an acrylic rubber composition (2) were obtained in the same manner as in Example 1 except that the acrylic rubber (A2) was used instead of the acrylic rubber (A1) of Example 1. Similarly, measurement and evaluation were performed, and the results are shown in Table 1.

Example 3
Instead of the polyoxyethylene dodecyl ether as the polyalkylene glycol ether compound (B2) to be blended when preparing the monomer emulsion, a polyoxyethylene monostearate ester (B1) as a polyalkylene glycol ester (B1) A monomer emulsion was obtained in the same manner as in Example 1 except that 1.4 parts of the trade name “Nonion S40”, weight average molecular weight (Mw) = about 4800, manufactured by NOF Corporation) was used. Next, using the obtained monomer emulsion, emulsion polymerization was performed in the same manner as in Example 1 to obtain an emulsion polymerization solution.
Next, using the emulsion polymerization liquid obtained above, the mixed liquid was prepared and coagulated in the same manner as in Example 1 to obtain a hydrated crumb of acrylic rubber (A3). In addition, the water-containing crumb of acrylic rubber (A3) was washed with water four times, pickled, and pure water in the same manner as in Example 1. And about the water-containing crumb after washing | cleaning, according to the said method, the mutual attachment property of the water-containing crumb after washing | cleaning was measured. The results are shown in Table 1.

Next, the washed hydrated crumb was dried at 110 ° C. for 1 hour with a hot air drier to obtain a solid acrylic rubber (A3), the polymer moisture content was measured, and the results are shown in Table 1. It was.
The acrylic rubber (A3) obtained had a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the acrylic rubber (A3) had a glass transition temperature (Tg) of −30 ° C., and the acrylic rubber (A3) recovery rate was 100%. Yes, an acrylic rubber (A3 was composed of 49.3% by weight of ethyl acrylate unit, 49.3% by weight of n-butyl acrylate unit, and 1.4% by weight of mono n-butyl fumarate unit.
Instead of the acrylic rubber (A1) of Example 1, an acrylic rubber (1) and an acrylic rubber composition (2) were obtained in the same manner as in Example 1 except that A3 was used. Measurements and evaluations were performed in the same manner, and the results are shown in Table 1.

Example 4
Using an emulsion polymerization solution obtained in the same manner as in Example 1, mixing was performed in the same manner as in Example 1 except that polyoxyethylene stearyl ether phosphoric acid as a polyalkylene glycol ester (B1) was not blended. The liquid was prepared and coagulated to obtain a hydrated crumb of acrylic rubber (A4).
Next, the water-containing crumb of the obtained acrylic rubber (A4) was subjected to four times of water washing, acid washing and pure water washing in the same manner as in Example 1. And about the water-containing crumb after washing | cleaning, according to the said method, the mutual attachment property of the water-containing crumb after washing | cleaning was measured. The results are shown in Table 1.

Next, the washed hydrated crumb was dried at 110 ° C. for 1 hour with a hot air dryer to obtain a solid acrylic rubber (A4), the polymer moisture content was measured, and the results are shown in Table 1. It was.
The resulting acrylic rubber (A4) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the acrylic rubber (A4) has a glass transition temperature (Tg) of −30 ° C., and the recovery rate of the acrylic rubber (A4) is 100%. The composition of the acrylic rubber (A4) was 49.3% by weight of ethyl acrylate units, 49.3% by weight of n-butyl acrylate units, and 1.4% by weight of mono n-butyl fumarate units.
An acrylic rubber composition (1) and an acrylic rubber composition (2) were obtained in the same manner as in Example 1 except that the acrylic rubber (A4) was used instead of the acrylic rubber (A1) of Example 1. Similarly, measurement and evaluation were performed, and the results are shown in Table 1.

Example 5
Using the emulsion polymerization solution obtained in the same manner as in Example 1, the addition amount of polyethylene glycol as the polyalkylene glycol (A) to 0.1 part by weight of the emulsion polymerization solution obtained in the same manner as in Example 1 was set to 0. While changing from 011 parts to 0.42 parts (1.4 parts with respect to a total of 100 parts of the charged monomers used in producing the emulsion polymerization liquid), the polyalkylene glycol ester (B1) A mixed solution was prepared and coagulated in the same manner as in Production Example 1 except that polyoxyethylene stearyl ether phosphoric acid was not blended to obtain a hydrated crumb of acrylic rubber (A5).
Next, the water-containing crumb of the obtained acrylic rubber (A5) was washed with water four times, pickled and pure water in the same manner as in Example 1. And about the water-containing crumb after washing | cleaning, according to the said method, the mutual attachment property of the water-containing crumb after washing | cleaning was measured. The results are shown in Table 1.

Next, the washed hydrated crumb was dried at 110 ° C. for 1 hour in a hot air dryer to obtain a solid acrylic rubber (A5), the polymer moisture content was measured, and the results are shown in Table 1. It was.
The resulting acrylic rubber (A5) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the acrylic rubber (A5) has a glass transition temperature (Tg) of −30 ° C., and the recovery rate of the acrylic rubber (A5) is 100%. The composition of the acrylic rubber (A5) was 49.3% by weight of ethyl acrylate units, 49.3% by weight of n-butyl acrylate units, and 1.4% by weight of mono n-butyl fumarate units.
An acrylic rubber composition (1) and an acrylic rubber composition (2) were obtained in the same manner as in Example 1 except that the acrylic rubber (A5) was used instead of the acrylic rubber (A1) of Example 1. Similarly, measurement and evaluation were performed, and the results are shown in Table 1.

Example 6
A monomer emulsion was obtained in the same manner as in Example 1 except that the polyoxyethylene dodecyl ether as the polyalkylene glycol ether compound (B2) was not blended. Next, using the obtained monomer emulsion, emulsion polymerization was performed in the same manner as in Example 1 to obtain an emulsion polymerization solution.
Next, using the emulsion polymerization solution obtained above, 0.011 part of polyethylene glycol as polyalkylene glycol (A) is added to 100 parts by weight of the emulsion polymerization solution obtained in the same manner as in Example 1. In the same manner as in Example 1, except that the mixture was changed from 0.09 parts to 0.09 parts (0.3 parts with respect to a total of 100 parts of the charged monomers used in producing the emulsion polymerization liquid). Preparation and coagulation were performed to obtain a hydrous crumb of acrylic rubber (A6).

Next, the water-containing crumb of the obtained acrylic rubber (A6) was washed four times with water, pickled and pure water in the same manner as in Production Example 1. And about the water-containing crumb after washing | cleaning, according to the said method, the mutual attachment property of the water-containing crumb after washing | cleaning was measured. The results are shown in Table 1.
Next, the washed hydrated crumb was dried at 110 ° C. for 1 hour with a hot air dryer to obtain a solid acrylic rubber (A6), the polymer moisture content was measured, and the results are shown in Table 1. It was.
The resulting acrylic rubber (A6) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the glass transition temperature (Tg) of the acrylic rubber (A6) is −30 ° C., and the recovery rate of the acrylic rubber (A6) is 100%. The composition of the acrylic rubber (A6) was 49.3% by weight of ethyl acrylate units, 49.3% by weight of n-butyl acrylate units, and 1.4% by weight of mono n-butyl fumarate units.
An acrylic rubber composition (1) and an acrylic rubber composition (2) were obtained in the same manner as in Example 1, except that the acrylic rubber (A6) was used instead of the acrylic rubber (A1) of Example 1. Similarly, measurement and evaluation were performed, and the results are shown in Table 1.

[Comparative Example 1]
Addition of polyethylene glycol as polyalkylene glycol (A) without using polyoxyethylene stearyl ether phosphoric acid as ester (B1) of polyalkylene glycol using the emulsion polymerization solution obtained in the same manner as in Example 6 Except for changing the amount from 0.09 part to 0.011 part, the mixture was prepared and coagulated in the same manner as in Example 6 to obtain a hydrous crumb of acrylic rubber (B1).
Next, the water-containing crumb of the obtained acrylic rubber (B1) was washed with water four times, pickled and pure water in the same manner as in Example 1. And about the water-containing crumb after washing | cleaning, according to the said method, the mutual attachment property of the water-containing crumb after washing | cleaning was measured. The results are shown in Table 1.

Next, the washed hydrated crumb was dried at 110 ° C. for 1 hour with a hot air drier to obtain a solid acrylic rubber (B1), the polymer moisture content was measured, and the results are shown in Table 1. It was.
The resulting acrylic rubber (B1) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the acrylic rubber (B1) has a glass transition temperature (Tg) of −30 ° C., and the recovery rate of the acrylic rubber (B1) is 100%. The composition of the acrylic rubber (B1) was 49.3% by weight of ethyl acrylate units, 49.3% by weight of n-butyl acrylate units, and 1.4% by weight of mono n-butyl fumarate units.
An acrylic rubber composition (1) and an acrylic rubber composition (2) were obtained in the same manner as in Example 1, except that the acrylic rubber (B1) was used instead of the acrylic rubber (A1) of Example 1. Similarly, measurement and evaluation were performed, and the results are shown in Table 1.

[Comparative Example 2]
Using the emulsion polymerization solution obtained in the same manner as in Comparative Example 1, the addition amount of polyethylene glycol as the polyalkylene glycol (A) to 0.1 part by weight of the emulsion polymerization solution obtained in the same manner as in Comparative Example 1. In addition to changing from 011 parts to 1.2 parts (4 parts with respect to a total of 100 parts of the charged monomers used in producing the emulsion polymerization liquid), the polyoxyalkylene glycol ester (B1) A mixed liquid was prepared and coagulated in the same manner as in Comparative Example 1 except that ethylene stearyl ether phosphoric acid was not blended to obtain a hydrated crumb of acrylic rubber (B2).
Next, the water-containing crumb of the obtained acrylic rubber (B2) was washed with water four times, pickled and pure water in the same manner as in Example 1. And about the water-containing crumb after washing | cleaning, according to the said method, the mutual attachment property of the water-containing crumb after washing | cleaning was measured. The results are shown in Table 1.

Next, the washed hydrated crumb was dried at 110 ° C. for 1 hour with a hot air dryer to obtain a solid acrylic rubber (B2), and the water content of the polymer was measured. The results are shown in Table 1. It was.
The resulting acrylic rubber (B2) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the acrylic rubber (B2) has a glass transition temperature (Tg) of −30 ° C., and the recovery rate of the acrylic rubber (B2) is 100%. The composition of the acrylic rubber (B2) was 49.3% by weight of ethyl acrylate units, 49.3% by weight of n-butyl acrylate units, and 1.4% by weight of mono n-butyl fumarate units.
An acrylic rubber composition (1) and an acrylic rubber composition (2) were obtained in the same manner as in Example 1, except that the acrylic rubber (B2) was used instead of the acrylic rubber (A1) of Example 1. Similarly, measurement and evaluation were performed, and the results are shown in Table 1.

[Comparative Example 3]
Using the emulsion polymerization solution obtained in the same manner as in Example 6, except that polyethylene glycol as the polyalkylene glycol (A) was not blended, the preparation of the mixed solution and the coagulation operation were performed in the same manner as in Example 6. The hydrated crumb of acrylic rubber (B3) was obtained.
Next, the water-containing crumb of the obtained acrylic rubber (B3) was washed with water four times, pickled and pure water in the same manner as in Example 1. And about the water-containing crumb after washing | cleaning, according to the said method, the mutual attachment property of the water-containing crumb after washing | cleaning was measured. The results are shown in Table 1.
Next, the washed hydrated crumb was dried at 110 ° C. for 1 hour in a hot air dryer to obtain a solid acrylic rubber (B3), and the water content of the polymer was measured. The results are shown in Table 1. It was.

The resulting acrylic rubber (B3) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the glass transition temperature (Tg) of the acrylic rubber (B3) is −30 ° C., and the recovery rate of the acrylic rubber (B3) is 51%. The composition of the acrylic rubber (B3) was 49.3% by weight of ethyl acrylate units, 49.3% by weight of n-butyl acrylate units, and 1.4% by weight of mono n-butyl fumarate units.
An acrylic rubber composition (1) and an acrylic rubber composition (2) were obtained in the same manner as in Example 1, except that the acrylic rubber (B3) was used instead of the acrylic rubber (A1) of Example 1. Similarly, measurement and evaluation were performed, and the results are shown in Table 1.

[Comparative Example 4]
Using the emulsion polymerization solution obtained in the same manner as in Example 1, polyethylene glycol as polyalkylene glycol (A) and polyoxyethylene stearyl ether phosphoric acid as polyalkylene glycol ester (B1) were not blended. Except for the above, the mixture was prepared and coagulated in the same manner as in Example 1 to obtain a hydrous crumb of acrylic rubber (B4).
Next, the water-containing crumb of the obtained acrylic rubber (B4) was washed with water four times, pickled and pure water in the same manner as in Example 1. And about the water-containing crumb after washing | cleaning, according to the said method, the mutual attachment property of the water-containing crumb after washing | cleaning was measured. The results are shown in Table 1.

Next, the washed hydrated crumb was dried at 110 ° C. for 1 hour in a hot air dryer to obtain a solid acrylic rubber (B4), and the water content of the polymer was measured. The results are shown in Table 1. It was.
The resulting acrylic rubber (B4) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the acrylic rubber (B4) has a glass transition temperature (Tg) of −30 ° C., and the recovery rate of the acrylic rubber (B4) is 48%. The composition of the acrylic rubber (B4) was 49.3% by weight of ethyl acrylate units, 49.3% by weight of n-butyl acrylate units, and 1.4% by weight of mono n-butyl fumarate units.
An acrylic rubber composition (1) and an acrylic rubber composition (2) were obtained in the same manner as in Example 1, except that the acrylic rubber (B4) was used instead of the acrylic rubber (A1) of Example 1. Similarly, measurement and evaluation were performed, and the results are shown in Table 1.

[Reference Example 1]
A mixed liquid was prepared in the same manner as in Example 1 except that the emulsion polymerization liquid obtained in the same manner as in Example 1 was used and polyethylene glycol as the polyalkylene glycol (A) was not blended. Next, the same procedure as in Example 1 was performed except that the amount of sodium sulfate used as the coagulant was changed from 3.3 parts to 7 parts (23.3 parts with respect to 100 parts of the polymer contained in the mixed solution). By performing the coagulation operation, a water-containing crumb of the acrylic rubber (C1) was obtained. Further, the water-containing crumb of the obtained acrylic rubber (C1) was washed with water four times in the same manner as in Example 1, pickling, And pure water washing was performed. And about the water-containing crumb after washing | cleaning, according to the said method, the mutual attachment property of the water-containing crumb after washing | cleaning was measured. The results are shown in Table 1.
Next, the washed hydrated crumb was dried at 110 ° C. for 1 hour in a hot air dryer to obtain a solid acrylic rubber (C1), the polymer moisture content was measured, and the results are shown in Table 1. It was.

The resulting acrylic rubber (C1) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 33, the glass transition temperature (Tg) of the acrylic rubber (C1) is −30 ° C., and the recovery rate of the acrylic rubber (C1) is 81%. The composition of the acrylic rubber (C1) was 49.3% by weight of ethyl acrylate units, 49.3% by weight of n-butyl acrylate units, and 1.4% by weight of mono n-butyl fumarate units.
An acrylic rubber composition (1) and an acrylic rubber composition (2) were obtained in the same manner as in Example 1, except that the acrylic rubber (C1) was used instead of the acrylic rubber (A1) of Example 1. Similarly, measurement and evaluation were performed, and the results are shown in Table 1.

（＊１）表１中の添加時期は、「Ｍ」が乳化重合前の単量体乳化液への添加、「Ｐ」が乳化重合後の乳化重合液への添加を示す。

(* 1) In the addition time in Table 1, “M” indicates addition to the monomer emulsion before emulsion polymerization, and “P” indicates addition to the emulsion polymerization solution after emulsion polymerization.

  From Table 1, in the presence of a compound having two or more types of polyoxyalkylene skeletons having different terminal structures, specifically, polyalkylene glycol (A) and polyalkylene glycol ester (B1) and / or polyalkylene glycol The acrylic rubber of the present invention obtained by coagulating an emulsion polymerization solution in the presence of the ether compound (B2) suppresses the mutual adhesion of water-containing crumbs and is excellent in polymer recovery and drying properties. The rubber composition obtained using acrylic rubber has low tack strength in the probe tack test, and is excellent in productivity and roll processability in a dryer, etc. It is excellent in water resistance, and it turns out that it is excellent in all the five characteristics (Examples 1-6).

  On the other hand, when coagulation is carried out using only one kind of glycol structure at the end having a polyoxyalkylene skeleton, the resulting acrylic rubber is produced with water-containing crumbs adhering to each other and poorly drying, and having a tack strength of 3N or more. It turns out that it is inferior to property and roll workability (comparative example 1). When the amount of polyethylene glycol used in Comparative Example 1 is increased, it is understood that there is a problem that water resistance is extremely deteriorated, although the mutual adhesion, drying property and tackiness of the hydrous crumb are improved (Comparative Example 2). . In addition, coagulation using only one of the ester compounds esterified with a terminal structure having a polyoxyalkylene skeleton not only deteriorates the adhesion and drying properties of the hydrous crumb but also reduces the polymer recovery by half. It turns out that there is only (Comparative Example 3). Further, when coagulation is carried out using only one of the ether compounds whose terminal structure having a polyoxyalkylene skeleton does not have an ester group, not only the tackiness is extremely bad but also the polymer recovery is less than half. It can be seen (Comparative Example 4). From these comparative examples, it can be seen that it is difficult to balance the five characteristics of tackiness and water resistance as a rubber composition and a rubber cross-linked product as a result of mutual adhesion of water-containing crumb, polymer recovery rate, drying property, and rubber composition (Comparative Example 1). ~ 4). That is, in the comparative example, one of the properties is extremely deteriorated (Comparative Examples 1 to 4), but the acrylic rubber of the present invention has five properties without any of these difficult properties being extremely deteriorated. Is well balanced (Examples 1-6).

  In addition, when an ester compound having a polyoxyalkylene skeleton having an esterified terminal structure is combined with an ether compound having a polyoxyalkylene skeleton having no terminal group, the four characteristics are highly balanced. It can be seen that the polymer recovery rate is somewhat inferior (Reference Example 1). Although not shown in this example, these ester compounds and ether compounds improve the polymer recovery rate as the amount increases, but the water resistance becomes somewhat worse, so it is important to balance these two characteristics. (Reference Example 1). On the other hand, when the glycol compound which has a polyoxyalkylene frame | skeleton is combined, it turns out that a polymer recovery rate will be as favorable as 100% in any combination (Examples 1-6).

In the present invention, it was further found that when three types of glycol compounds, ester compounds and ether compounds having a polyoxyalkylene skeleton and different terminal structures are combined, all five properties are highly balanced ( Examples 1 to 3).
In the present invention, in particular, a polyalkylene glycol having a polyoxyalkylene skeleton does not show a great effect by itself (Comparative Examples 1 and 2), but an ester compound having a polyoxyalkylene skeleton and other terminal structure It turns out that a big synergistic effect is shown when it combines with an ether compound (Examples 1-6). Moreover, the polyalkylene glycol having a polyoxyalkylene skeleton is, for example, 99.26 / 0.74 in a weight ratio of (ester compound having a polyoxyalkylene skeleton + ether compound) / (glycol compound having a polyoxyalkylene skeleton). It is a feature that a large synergistic effect can be exhibited even with an extremely small amount (Examples 1 to 3).

Claims (13)

An emulsion polymerization step of emulsion polymerization of a monomer having (meth) acrylic acid ester as a main component using a polymerization catalyst to obtain an emulsion polymerization solution;
A coagulation step in which the emulsion polymerization liquid is coagulated in the presence of the polyalkylene glycol (A) and the polyalkylene glycol ester (B1) and / or the polyalkylene glycol ether compound (B2) to obtain a hydrous crumb;
A cleaning process for cleaning the hydrous crumb;
A drying process for drying the washed hydrous crumb;
A method for producing acrylic rubber comprising:   The method for producing an acrylic rubber according to claim 1, wherein the polymerization catalyst contains a peroxide, ferrous sulfate, and ascorbic acid (salt).   The method for producing an acrylic rubber according to claim 1 or 2, wherein the addition of the polyalkylene glycol (A) is performed in an emulsion polymerization solution after emulsion polymerization.   The addition of the polyalkylene glycol ester (B1) and / or the polyalkylene glycol ether compound (B2) is a monomer emulsion before emulsion polymerization and / or an emulsion polymerization solution after emulsion polymerization. 4. A method for producing an acrylic rubber according to any one of 3 above.   The polyalkylene glycol ester (B1) and / or the polyalkylene glycol ether compound (B2) is selected from the group consisting of a polyoxyalkylene phosphate ester, a polyoxyalkylene sulfate ester, a polyoxyalkylene fatty acid ester, and a polyoxyalkylene ether ester. It is a polyoxyalkylene ether compound having no at least one ester group selected from the group consisting of at least one polyoxyalkylene ester compound selected from the group consisting of a polyoxyalkylene alkyl ether and a polyoxyalkylene aryl ether. Item 5. A method for producing acrylic rubber according to any one of Items 1 to 4.   The method for producing an acrylic rubber according to any one of claims 1 to 5, wherein the solidification of the emulsion polymerization liquid is carried out by contact between the emulsion polymerization liquid and a sulfate compound.   Solidification temperature is 60 degreeC or more, The manufacturing method of the acrylic rubber in any one of Claims 1-6.   The (meth) acrylic acid ester unit obtained by the production method according to claim 1 is 50 to 99.9% by weight, the crosslinkable monomer unit is 0.01 to 20% by weight, and copolymerization Acrylic rubber with 0 to 49.99% by weight of other possible monomer units.   The acrylic rubber according to claim 8, wherein the crosslinkable monomer unit is a carboxyl group-containing monomer unit.   The acrylic rubber according to claim 8 or 9, wherein the Mooney viscosity is in the range of 10 to 150.   A rubber composition comprising a rubber component containing the acrylic rubber according to claim 9 and a crosslinking agent.   The rubber composition according to claim 11, further comprising a crosslinking accelerator, an anti-aging agent, a filler, or a silane coupling agent.   A crosslinked rubber product obtained by crosslinking the rubber composition according to claim 11 or 12.