JP6753431B2 - Acrylic rubber manufacturing method, and acrylic rubber, rubber composition, and rubber crosslinked product obtained by the manufacturing method. - Google Patents

Description

The present invention relates to a method for producing acrylic rubber, an acrylic rubber obtained by the production method, a rubber composition containing the same, and a crosslinked rubber product obtained by cross-linking the rubber composition. A method for producing acrylic rubber, which is excellent in pot stain prevention and polymer recoverability, and also in water resistance and compression permanent strain resistance when crosslinked, acrylic rubber obtained by the manufacturing method, a rubber composition containing the same, and The present invention relates to a rubber crosslinked product obtained by cross-linking the rubber composition.

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

Such acrylic rubber is usually obtained by emulsion-polymerizing a monomer mixture constituting acrylic rubber, coagulating it by adding a coagulant to the obtained emulsion polymerization solution, and drying the hydrous crumb obtained by coagulation. (For example, see Patent Document 1). A hot air dryer is usually used for drying the hydrous crumb, but from the viewpoint of productivity, a drying device such as a belt conveyor type band dryer capable of drying in a continuous process is used. On the other hand, such a method for producing acrylic rubber has problems that the pot is too dirty after solidification to be continuously produced, and the recovery rate of the solidified polymer is not sufficient. Further, problems such as insufficient water resistance, compression set, storage stability and the like when the acrylic rubbers obtained by these production methods are crosslinked have become major problems.

JP-A-7-145291

The present invention has been made in view of such an actual situation, and can be produced with a high polymer recovery rate without causing pot stains during production, and is also water resistant and compression resistant when crosslinked. An object of the present invention is to provide a method for producing acrylic rubber having excellent strain resistance.

The present inventors can suppress stains on the polymerization tank by coagulating an emulsion polymerization solution obtained by emulsion polymerization of a monomer containing a (meth) acrylic acid ester as a main component in the presence of a specific compound and with a specific coagulant. The polymer can be recovered with high efficiency, and the rubber composition containing the obtained acrylic rubber and a cross-linking agent is excellent in storage stability. When the polymer is cross-linked, it is excellent in water resistance and compression set resistance. It was found that a rubber crosslinked product can be obtained.

The present inventors have also achieved the effects of the present invention by using a specific polymerization catalyst, when the weight average molecular weight of the specific compound is in a specific range, and by combining acid cleaning and water cleaning in the cleaning step. I found that it could be significantly enhanced.
The present inventors further, in the rubber composition containing the acrylic rubber and the cross-linking agent of the present invention, by blending a specific compounding agent, storage stability, water resistance at the time of cross-linking, and compression resistance permanent strain It was found that the sex was highly enhanced.
The present inventors have completed the present invention based on these findings.

Thus, according to the present invention, the emulsion polymerization step of obtaining an emulsion polymerization solution by emulsion polymerization of a monomer containing a (meth) acrylic acid ester as a main component in the presence of an emulsifier using a polymerization catalyst, and the emulsion polymerization solution. It comprises a coagulation step of contacting with a metal sulfate in the presence of an alkylene oxide polymer to obtain a hydrous crumb, a washing step of washing the hydrous crumb, and a drying step of drying the washed hydrous crumb. A method for producing acrylic rubber is provided.
In the method for producing acrylic rubber of the present invention, it is preferable that the polymerization initiator is a combination of a peroxide, ferrous sulfate, ascorbic acid and / or ascorbic acid salt.
In the method for producing acrylic rubber of the present invention, by adding the alkylene oxide polymer to the monomer emulsion before emulsion polymerization and / or the emulsion polymerization solution after emulsion polymerization, the emulsification occurs at the time of solidification. It is preferable that the alkylene oxide polymer is present in the polymerization solution.
In the method for producing acrylic rubber of the present invention, the weight average molecular weight (Mw) of the alkylene oxide polymer is preferably in the range of 10,000 to 6,000,000.
In the method for producing acrylic rubber of the present invention, the contact between the emulsion polymerization solution and the metal sulfate adds the metal sulfate to the emulsion polymerization solution, or disperses the emulsion polymerization solution into a solution or dispersion of the metal sulfate. It is preferable to use either method of adding to a liquid.
In the method for producing acrylic rubber of the present invention, it is preferable that the cleaning in the cleaning step includes acid cleaning.

Further, according to the present invention, acrylic rubber produced by the above production method is provided.
In the acrylic rubber of the present invention, the monomer composition is 50 to 99.9% by weight of the (meth) acrylic acid ester monomer unit, 0.01 to 20% by weight of the crosslinkable monomer unit, and copolymerizable. The monomer unit of the above is preferably 0 to 50% by weight.
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 (ML1 + 4, 100 ° C.) is preferably in the range of 10 to 150.

Further, according to the present invention, there is provided a rubber composition containing the above-mentioned rubber component containing acrylic rubber and a cross-linking agent.
In the rubber composition of the present invention, it is preferable that at least one compounding agent selected from the group consisting of a cross-linking accelerator, a filler and a silane coupling is further blended.
Further, according to the present invention, a rubber crosslinked product obtained by crosslinking the above rubber composition is provided.

According to the present invention, acrylic does not cause stains on the pot during production, can be produced with a high polymer recovery rate, has excellent storage stability, and has excellent water resistance and compression set resistance when crosslinked. It is possible to provide a method for producing rubber, acrylic rubber obtained by the production method, a rubber composition containing the same, and a crosslinked rubber product obtained by cross-linking the rubber composition.

[Production method]
The method for producing acrylic rubber of the present invention includes an emulsion polymerization step of emulsion-polymerizing a monomer containing (meth) acrylic acid ester as a main component in the presence of an emulsifier using a polymerization catalyst to obtain an emulsion polymerization solution, and the emulsion polymerization step. A coagulation step of bringing a polymer solution into contact with a metal sulfate in the presence of an alkylene oxide polymer to solidify it to obtain a hydrous crumb, a washing step of washing the hydrous crumb, and a drying step of drying the washed hydrous crumb. It is characterized by being prepared with.

<Polymer>
The monomer used in the present invention is characterized by containing (meth) acrylic acid ester as a main component. The (meth) acrylic acid ester as the main component is not particularly limited, and examples thereof include (meth) acrylic acid alkyl ester and (meth) acrylic acid alkoxyalkyl ester.

As the (meth) acrylic acid alkyl ester, for example, an ester of alkanol having 1 to 12 carbon atoms and (meth) acrylic acid is used, and an ester of alkanol having 1 to 8 carbon atoms and (meth) acrylic acid is preferable. , Esters of alkanol having 2 to 6 carbon atoms and (meth) acrylic acid are more preferable. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate. , N-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, etc. Among these, ethyl (meth) acrylate, n-butyl (meth) acrylate Ethyl acrylate and n-butyl acrylate are particularly preferred.

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

These (meth) acrylic acid esters can be used alone or in combination of two or more. The content of the (meth) acrylic acid ester in the monomer used for the polymerization is usually 50 to 99.9% by weight, preferably 60 to 99.7% by weight, and more preferably 70 to 99.5% by weight. .. If the content of the (meth) acrylic ester is excessively low, the weather resistance, heat resistance, and oil resistance of the obtained rubber crosslinked product may decrease, while if it is excessively high, the obtained rubber crosslinked product may be deteriorated. Heat resistance may decrease. Further, as the (meth) acrylic acid ester, it is preferable to use one composed of 30 to 100% by weight of the (meth) acrylic acid alkyl ester and 70 to 0% by weight of the (meth) acrylic acid alkoxyalkyl ester.

As the monomer used for polymerization in the emulsion polymerization step of the present invention, the improvement effect of the present invention is greatly preferable by containing a crosslinkable monomer together with the above (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, and a carboxyl group is preferable. When it is a containing monomer, an epoxy group-containing monomer, a halogen atom-containing monomer, and more preferably a carboxyl group-containing monomer, the compression set property when the acrylic rubber is crosslinked is highly improved. It is suitable.

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, and the like. Examples thereof include a monoester of α, β-ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms and alkanol having 1 to 8 carbon atoms. It is preferable to use α, β-ethylenically unsaturated carboxylic acid because it is possible to further enhance the compression set resistance when the obtained acrylic rubber is a crosslinked rubber 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 butenedioic acid such as fumaric acid and maleic acid, itaconic acid, citraconic acid, and chloromaleic acid. Examples of monoesters of α, β-ethylenic 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. Itaconic acid monochain alkyl esters such as monomethyl, monoethyl maleate, monon-butyl maleate; monocyclopentyl fumarate, monocyclohexyl fumarate, monocyclohexenyl fumarate, monocyclopentyl maleate, monocyclohexyl maleate, maleic acid Examples thereof include butenedioic acid monoesters having an alicyclic structure such as monocyclohexenyl; itaconic acid monoesters such as monomethyl itaconic acid, monoethyl itaconic acid, monon-butyl itaconic acid, and monocyclohexyl itaconic acid.

As the carboxyl group-containing monomer, α, β-ethylenically unsaturated carboxylic acid is preferable, and a monoester of α, β-ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms and alkanol having 1 to 8 carbon atoms is preferable. Is more preferable, and a butendionic acid monochain alkyl ester and a butendionic acid monoester having an alicyclic structure are particularly preferable. Specific preferred examples include mono-butyl fumarate, mono-n-butyl maleate, monocyclohexyl fumarate, monocyclohexyl maleate and the like, with mono n-butyl fumarate being particularly preferred. Among the above-mentioned monomers, the dicarboxylic acid includes those existing as anhydrides.

The epoxy group-containing monomer is not particularly limited, but for example, an epoxy group-containing (meth) acrylic acid ester such as glycidyl (meth) acrylate; an epoxy group-containing styrene such as p-vinylbenzyl glycidyl ether; allyl. Glycidyl ether and vinyl glycidyl ether, 3,4-epoxide-1-pentene, 3,4-epoxide-1-butene, 4,5-epoxide-2-pentene, 4-vinylcyclohexylglycidyl ether, cyclohexenylmethylglycidyl ether, Epoxide group-containing ethers such as 3,4-epoxide-1-vinylcyclohexene and allylphenylglycidyl ether; and the like.

The halogen atom-containing monomer is not particularly limited, but for example, an unsaturated alcohol ester of a halogen-containing saturated carboxylic acid, a (meth) acrylic acid haloalkyl ester, a (meth) acrylic acid haloacyloxyalkyl ester, (meth). Examples thereof 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 the 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) acrylic acid, 1-chloroethyl (meth) acrylic acid, 2-chloroethyl (meth) acrylic acid, and 1,2-dichloroethyl (meth) acrylic acid. Examples thereof include 2-chloropropyl (meth) acrylic acid, 3-chloropropyl (meth) acrylic acid, and 2,3-dichloropropyl (meth) acrylic acid. Examples of the (meth) acrylic acid haloacyloxyalkyl ester include (meth) acrylic acid 2- (chloroacetoxy) ethyl, (meth) acrylic acid 2- (chloroacetoxy) propyl, and (meth) acrylic acid 3- (chloroacetoxy). ) Propyl, 3- (hydroxychloroacetoxy) propyl (meth) acrylate and the like. Examples of the (meth) acrylic acid (haloacetylcarbamoyloxy) alkyl ester include (meth) acrylic acid 2- (chloroacetylcarbamoyloxy) ethyl and (meth) acrylic acid 3- (chloroacetylcarbamoyloxy) propyl. Be done. Examples of the halogen-containing unsaturated ether include chloromethyl vinyl ether, 2-chloroethyl vinyl ether, 3-chloropropyl vinyl ether, 2-chloroethyl allyl ether, 3-chloropropyl allyl ether and the like. 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, p-chloromethyl-α-methylstyrene and the like. Examples of the halogen-containing unsaturated amide include N-chloromethyl (meth) acrylamide. Examples of the haloacetyl group-containing unsaturated monomer include 3- (hydroxychloroacetoxy) propylallyl ether and p-vinylbenzylchloroacetic acid ester.

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

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 in the range of 0.01 to 20% by weight, preferably 0.1 to 10% by weight, and more preferably 0.5 to 5% by weight. By setting the content of the crosslinkable monomer within the above range, the pot of the polymerization tank is not contaminated during the production of acrylic rubber, the rubber recovery rate is high, and it is suitable. It is suitable because it can highly improve the compression resistance and permanent strain resistance.

The monomer used in the present invention may contain other monomers copolymerizable, if necessary, in addition to the above (meth) acrylic acid ester and crosslinkable monomer. The other copolymerizable monomers are not particularly limited as long as they can be copolymerized, but for example, aromatic vinyl monomers, α, β-ethylenically unsaturated nitrile monomers, and acrylamide-based singles. Quantities, other olefin-based monomers and the like can be mentioned. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, divinylbenzene and the like. Examples of the α, β-ethylenically unsaturated nitrile monomer include acrylonitrile and methacrylonitrile. Examples of the acrylamide-based monomer include acrylamide and methacrylamide. Examples of other olefin-based monomers include ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl acetate, ethyl vinyl ether, and butyl vinyl ether. 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, and 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 the above-mentioned (meth) acrylate-based monomer is emulsion-polymerized in the presence of an emulsifier using a polymerization catalyst to obtain an emulsion polymerization solution.

As the emulsion polymerization method, a conventional method may be followed. For example, a monomer containing (meth) acrylic acid ester as a main component is mixed in advance with an emulsifier and water, and a polymerization initiator is added to carry out emulsion polymerization. The method etc. can be mentioned.

The emulsifier is not particularly limited, and examples thereof include a nonionic emulsifier, an anionic emulsifier, and a cationic emulsifier.
The nonionic emulsifier is not particularly limited, and is, for example, a polyoxyalkylene alkyl ether such as polyoxyethylene dodecyl ether; a polyoxyalkylene alkyl phenyl ether such as polyoxyethylene nonylphenyl ether; and a poly such as polyoxyethylene stearate ester. Oxyalkylene fatty acid ester; polyoxyethylene sorbitan alkyl ester; oxyalkylene copolymer such as polyoxyethylene / polypropylene oxide copolymer; and the like. Among these, polyoxyalkylene alkyl ether, polyoxyalkylene alkyl phenyl ether and the like are preferable, and polyoxyethylene alkyl ether and polyoxyethylene alkyl phenyl ether are particularly preferable. The weight average molecular weight of the nonionic emulsifier is not particularly limited, but is usually in the range of 300 to 50,000, preferably 500 to 30,000, and more preferably 1,000 to 15,000. These nonionic emulsifiers can be used alone or in combination of two or more.

The anionic emulsifier is not particularly limited, for example, 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. Higher phosphate ester salts such as sulfate ester salts and sodium alkyl phosphate esters; alkyl sulfosuccinates and the like can be mentioned. Among these anionic emulsifiers, higher phosphoric acid ester salts and higher alcohol sulfate ester salts are preferable. 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.

Each of these emulsifiers can be used alone or in combination of two or more, but 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 generation of stains due to adhesion of a polymer or the like to a polymerization apparatus (for example, a polymerization tank) during emulsion polymerization. It is possible to reduce the amount of the coagulant used, and as a result, the amount of the coagulant in the finally obtained acrylic rubber can be reduced, and the water resistance of the resulting rubber crosslinked product can be improved. it can. Further, by using a nonionic emulsifier and an anionic emulsifier in combination, the emulsifying action can be enhanced, so that the amount of the emulsifier itself used can be reduced, and as a result, in the finally obtained acrylic rubber. It is possible to reduce the residual amount of the emulsifier contained in the acrylic rubber, thereby further enhancing the water resistance of the obtained acrylic rubber.

The amount of the emulsifier used is the total amount of the emulsifier used with respect to 100 parts by weight of the monomer used for polymerization, and is usually 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, and more preferably 1 to 3 parts by weight. Is the range of. When the nonionic emulsifier and the anionic emulsifier are used in combination, the ratio of the nonionic emulsifier to the anionic emulsifier is usually 1/99 to 99/1, preferably 10/90 to 80/20, in terms of weight ratio of the nonionic emulsifier / anionic emulsifier. , More preferably 25/75 to 75/25, even more preferably 50/50 to 75/25, and most preferably 65/35 to 75/25, which is preferable because the object of the present application is highly enhanced. ..

Examples of the polymerization initiator include azo compounds such as azobisisobutyronitrile; organic peroxides such as diisopropylbenzene hydroperoxide, cumene hydroperoxide, paramentan hydroperoxide, and benzoyl peroxide; sodium persulfate and persulfate. Inorganic peroxides such as potassium, hydrogen peroxide, and ammonium persulfate; and the like can be used. These polymerization initiators can be used alone or in combination of two or more. 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. It is in the range of 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-based polymerization initiator in combination with a reducing agent. The reducing agent to be combined is not particularly limited, but is, for example, a metal ion-containing compound in a reduced state such as ferrous sulfate, sodium hexamethylenediamine tetraacetate, and cuprous naphthenate; ascorbic acid, sodium ascorbate, and ascorbin. Ascorbic acid (salt) such as potassium acid acid; erythorbic acid (salt) such as erythorbic acid, sodium elisorbate, potassium elisorbate; sugar; sulfinate such as sodium hydroxymethanesulfite; sodium sulfite, potassium sulfite, sodium hydrogen sulfite , Sodium hydrogen sulfite, potassium hydrogen sulfite sulfite; sodium pyrosulfite, potassium pyrosulfite, sodium pyrosulfite, potassium hydrogen sulfite, etc. pyrosulfite; sodium thiosulfite, potassium thiosulfite, etc. Sulfinic acid, sodium bisulfite, potassium bisulfite, sodium bisulfite, potassium bisulfite sulphonic acid (salt); pyrosulfite, sodium pyrosulfite, potassium pyrosulfite, sodium bisulfite, hydrogen pyrosulfite Pyrobisulfite (salt) such as potassium; sodium formaldehyde sulfiterate and the like.

Each of these reducing agents can be used alone or in combination of two or more, but contains a metal ion-containing compound in a reducing state as a first reducing agent and a metal ion-containing compound in a reducing state as a second reducing agent. Combined with other reducing agents other than compounds, preferably ferrous sulfate and ascorbic acid (salt) and / or sodium formaldehyde sulfoxylate, particularly preferably ferrous sulfate and ascorbate. By combining with, the water resistance and compression set resistance when the obtained acrylic rubber is used as a crosslinked product can be highly improved, which is preferable. The total 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 and / or ascorbic acid salt are used in combination, the amount of ferrous sulfate used is usually 0.00001 to 0. With respect to 100 parts by weight of the monomer used for polymerization. In the range of 01 parts by weight, preferably 0.0001 to 0.001 parts by weight, the amount of ascorbic acid and / or ascorbic acid salt used is usually 0.001 to 5 parts by weight, preferably 0.01 to 1 part by weight. Is the range of.

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

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

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

When the polymerization reaction is carried out while continuously dropping the monomer used for 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 add dropwise in the state of a monomeric emulsion. The method for preparing the monomer emulsion is not particularly limited, and a method of stirring the total amount of the monomer used for polymerization, the total amount of the emulsifier, and water using a stirrer such as a homomixer or a disk turbine may be used. Can be mentioned. The amount of water used in the monomer emulsion is preferably 10 to 70 parts by weight, more preferably 20 to 50 parts by weight, based on 100 parts by weight of the monomer used for polymerization.

In addition, when the polymerization reaction is carried out by continuously dropping the monomer, the polymerization initiator, and the reducing agent used for the polymerization into the polymerization reaction system from the start of the polymerization reaction to an arbitrary time, these are separated. The polymerization initiator and the reducing agent may be added dropwise to the polymerization system using the dropping device of the above, or at least the polymerization initiator and the reducing agent may be mixed in advance and, if necessary, dropped from the same dropping device as an aqueous solution into the polymerization system. You may. After the completion of the 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 carried out by adding a polymerization terminator, if necessary. Examples of the polymerization terminator include hydroxylamine, hydroxyamine sulfate, diethylhydroxyamine, hydroxyamine sulfonic acid and its alkali metal salt, sodium dimethyldithiocarbamate, hydroquinone and the like. The amount of the polymerization inhibitor used is not particularly limited, but is preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the monomer used for the polymerization.

<Addition of compounding agent to emulsion polymerization solution>
In the emulsion polymerization step in the production method of the present invention, various compounding agents may be added to the emulsion polymerization solution before solidification obtained by emulsion polymerization as necessary, and uniformly dispersed in the produced acrylic rubber polymer. it can. The compounding agent to be added is not particularly limited as long as it is a compounding agent for rubber, and for example, an antiaging agent is preferable.

By pre-containing the anti-aging agent in the emulsion polymerization solution before coagulation, deterioration of the acrylic rubber due to heat during drying in the drying step described later can be effectively suppressed. Specifically, it is possible to effectively suppress a decrease in Mooney viscosity due to deterioration due to heating during drying, which effectively improves normal tensile strength and elongation at break in the case of a crosslinked rubber product. It can be enhanced to. In addition, in the state of the emulsion polymerization solution before coagulation, the anti-aging agent can be appropriately dispersed by adding the anti-aging agent, so that even if the amount of the anti-aging agent is reduced, the amount of the anti-aging agent is reduced. The additive effect can be fully exerted. Specifically, the amount of the antiaging agent to be blended is preferably 0.1 to 2 parts by weight, more preferably 0.2 to 1.2 parts by weight, based on 100 parts by weight of the acrylic rubber component in the emulsion polymerization solution. Even if the blending amount is relatively small, the effect of the addition can be fully exhibited. Even if the anti-aging agent is contained in the emulsion polymerization solution before coagulation, the added anti-aging agent is not substantially removed in the subsequent coagulation, washing, drying, etc. , The addition effect can be fully exhibited. Further, as a method of adding an antiaging agent to the emulsion polymerization solution, a method of adding it to the emulsion polymerization solution after emulsion polymerization and before coagulation, or a method of adding it to the solution before emulsion polymerization is carried out. However, when it is added to the solution before the emulsion polymerization, agglomerates are generated during the emulsion polymerization, which may cause stains on the polymerization apparatus. Therefore, it is after the emulsion polymerization. Moreover, the method of adding to the emulsion polymerization solution before coagulation is preferable.

The anti-aging agent is not particularly limited, but for example, 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, mono (or di or tri) (α-methylbenzyl) phenol, etc. Phenol styrene, 2,2'-methylene-bis (6-α-methylbenzyl-p-cresol), 4,4'-methylenebis (2,6-di-t-butylfunol), 2,2'-methylene- Butylation of bis (4-methyl-6-t-butylphenol), 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate stearyl, alkylated bisphenol, p-cresol and dicyclopentadiene Phenolic anti-aging agent that does not contain sulfur atoms such as products; 2,4-bis [(octylthio) methyl] -6-methylphenol, 2,2'-thiobis- (4-methyl-6-t-butylphenol) , 4,4'-thiobis- (6-t-butyl-o-cresol), 2,6-di-t-butyl-4- (4,6-bis (octylthio) -1,3,5-triazine- 2-Ilamino) Phenol and other thiophenolic antioxidants; Tris (nonylphenyl) phosphite, diphenylisodecylphosphite, tetraphenyldipropylene glycol and diphosphite and other phosphite ester-based antioxidants; Dilauryl thiodipropionate Sulfur ester anti-aging agents such as: phenyl-α-naphthylamine, phenyl-β-naphthylamine, p- (p-toluenesulfonylamide) -diphenylamine, 4,4'-(α, α-dimethylbenzyl) diphenylamine, N, Amine-based anti-aging agents such as N-diphenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, butylaldehyde-aniline condensate; imidazole-based antiaging agents such as 2-mercaptobenzimidazole; Examples thereof include quinoline-based antioxidants such as 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinolin; and hydroquinone-based antioxidants 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 amount added thereof is usually 0.001 to 10% by weight with respect to 100 parts by weight of the acrylic rubber component in the emulsion polymerization solution. It is in the range of 0.01 to 5 parts by weight, more preferably 0.1 to 3 parts by weight.

<Coagulation process>
The coagulation step in the production method of the present invention is characterized in that the emulsion polymerization solution is brought into contact with a metal sulfate in the presence of an alkylene oxide polymer and coagulated to obtain a hydrous crumb.

The alkylene oxide polymer is not particularly limited, and examples thereof include polyethylene oxide, polypropylene oxide, ethylene oxide / propylene oxide copolymer, and the like, and polyethylene oxide is preferable among them.

The weight average molecular weight (Mw) of the alkylene oxide polymer is selected depending on the intended use, but is usually 10,000 to 6,000,000, preferably 30,000 to 1,000,000, and more preferably 50. It is in the range of 000 to 500,000, particularly preferably 50,000 to 300,000, most preferably 80,000 to 200,000. When the weight average molecular weight (Mw) of the alkylene oxide polymer is in this range, the acrylic rubber recovery rate during the production of acrylic rubber is high, the effect of suppressing the stain on the kettle of the polymerization tank is large, and the obtained acrylic rubber is crosslinked. It is suitable because it has remarkably excellent water resistance and compression set resistance when it is made into a product.

Each of these alkylene oxide polymers can be used alone or in combination of two or more, and the content thereof is usually 0.01 to 1 with respect to 100 parts by weight of the acrylic rubber component in the emulsion polymerization solution. It is in the range of parts by weight, preferably 0.01 to 0.6 parts by weight, more preferably 0.02 to 0.5 parts by weight.

The present invention is characterized in that the emulsion polymerization solution is coagulated in the presence of an alkylene oxide polymer. By preliminarily containing the polyalkylene oxide polymer in the emulsion polymerization solution before coagulation, the coagulation property of the emulsion polymerization solution can be improved, and thereby the amount of coagulant in the coagulation step can be reduced. Therefore, the residual amount in the finally obtained acrylic rubber can be reduced, and the compression set resistance and water resistance in the case of a rubber crosslinked product can be improved, which is preferable. Further, when the alkylene oxide polymer is present in the emulsion polymerization solution before solidification, it is preferable because the pot stain of the polymerization tank can be suppressed. The method of adding the alkylene oxide polymer to the emulsion polymerization solution is not particularly limited, but the alkylene oxide polymer is usually added to the monomer emulsion before emulsion polymerization and / or to the emulsion polymerization solution after emulsion polymerization. It is preferable to add it to the emulsion polymerization solution after emulsion polymerization in order to highly enhance the effect of the present invention.

The metal sulfate used as the coagulant is not particularly limited, but for example, a sulfate of a 1-valent metal can be preferably used, and a sulfate of a monovalent or divalent metal is more preferable. Specific examples thereof include sodium sulfate, 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. It is preferably sodium sulfate, magnesium sulfate and aluminum sulfate, and more preferably sodium sulfate and magnesium sulfate.

These metal sulfates can be used alone or in combination of two or more. The amount of the metal sulfate used is usually 0.01 to 100 parts by weight, preferably 0.1 to 50 parts by weight, and more preferably 1 to 30 parts by weight with respect to 100 parts by weight of the acrylic rubber component in the emulsion polymerization solution. Is the range of. When the metal sulfate is in this range, it is possible to achieve a high balance between storage stability and compression set resistance and water resistance when the acrylic rubber is crosslinked, while ensuring sufficient coagulation of the acrylic rubber. It is suitable.

In the coagulation step of the present invention, other coagulants can be used in combination with the metal sulfate, if necessary. Other coagulants include metals such as 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 tin chloride. Chlorides; 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, and the like. These other coagulants can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range that does not impair the effects of the present invention.

The method of contacting the emulsion polymerization solution with the metal sulfate may follow a conventional method, and a solution or dispersion of metal sulfate or metal sulfate is added to the emulsion polymerization solution, or the emulsion polymerization solution is made of metal sulfate. It can be carried out by adding it to a solution or a dispersion. An aqueous solution is usually used as the solution or dispersion of metal sulfuric acid when the emulsion polymerization solution is added, and the concentration of the metal sulfate in the aqueous solution is appropriately selected according to the purpose of use, and is usually 1 to 50% by weight, preferably. Is in the range of 5 to 40% by weight, more preferably 10 to 30% by weight.

The contact (coagulation) temperature between the emulsion polymerization solution and the metal sulfate is not particularly limited, but is usually in the range of 60 ° C. or higher, preferably 70 to 100 ° C., and more preferably 75 to 90 ° C.

<Washing process>
The cleaning step in the production method of the present invention is to clean the hydrous crumb obtained in the solidification step.

The washing method is not particularly limited, and examples thereof include a method in which water is used as a washing liquid and water washing is performed by mixing the added water together with the water-containing crumb. The temperature at the time of washing with water is not particularly limited, but is preferably 5 to 60 ° C., more preferably 10 to 50 ° C., and the mixing time is 1 to 60 minutes, more preferably 2 to 30 minutes.

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

The number of washings with water is not particularly limited and may be once, but from the viewpoint of reducing the residual amount of the coagulant in the finally obtained acrylic rubber, it is preferable to carry out the washing a plurality of times, preferably 2 to 10 times. , More preferably 3 to 8 times. From the viewpoint of reducing the residual amount of the coagulant in the finally obtained acrylic rubber, it is desirable that the number of washings with water is large, but even if the washing is performed beyond the above range, the effect of removing the coagulant is effective. Although it is small, the number of washings is preferably in the above range because the influence of the decrease in productivity becomes large due to the increase in the number of steps.

Further, in the present invention, after washing with water, acid washing using an acid as a cleaning liquid may be further performed. By performing acid cleaning, the storage stability of acrylic rubber can be highly enhanced, and the compression set resistance in the case of a crosslinked rubber product can also be enhanced, which is preferable.

The acid used for acid cleaning is not particularly limited, and sulfuric acid, hydrochloric acid, phosphoric acid and the like can be used without limitation. Further, in acid cleaning, when adding an acid to a hydrous crumb, it is preferable to add the acid in an aqueous solution state, and the acid concentration is usually 0.001 to 1% by weight, preferably 0.005 to 0.5. It is in the range of% by weight, more preferably 0.01 to 0.1% by weight, and most preferably 0.02 to 0.08% by weight. When the acid concentration is in this range, the effect of improving storage stability and compression set is maximized, which is preferable. The pH at that time is usually 6 or less, preferably 5 or less, and more preferably 4 or less. The pH of the washing water used for acid cleaning can be determined, for example, by measuring the pH of the water contained in the hydrous crumb after acid cleaning.

The temperature at the time of acid cleaning is not particularly limited, but is preferably 5 to 60 ° C., more preferably 10 to 50 ° C., and the mixing time is 1 to 60 minutes, more preferably 2 to 30 minutes.

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

<Drying process>
The drying step of the present invention is to dry the hydrous crumb that has been washed in the above washing step.

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

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 ~ 170 ° C.

[Acrylic rubber]
According to the present invention, the acrylic rubber of the present invention can be obtained by the above manufacturing method.
The acrylic rubber of the present invention thus obtained does not cause stains on the pot during production, can be produced with a high polymer recovery rate, has excellent storage stability, and is further made into a crosslinked rubber product. It is excellent in water resistance and compression set resistance.

The acrylic rubber of the present invention is not particularly limited except that it contains a (meth) acrylic acid ester monomer unit as a main component, but when it further contains a crosslinkable monomer unit, it has water resistance and compression permanent strain resistance. Is suitable because it is further enhanced.

The monomer composition in the acrylic rubber of the present invention is appropriately selected depending on the intended use, but the (meth) acrylic acid ester monomer unit is usually 50 to 99.9% by weight, preferably 60 to 99. It is 0.7% by weight, more preferably 70 to 99.5% by weight, and the content of the crosslinkable monomer unit is usually 0.01 to 20% by weight, preferably 0.1 to 10% by weight, more preferably. Is 0.5 to 5% by weight, and the content of other copolymerizable monomer units is usually 0 to 49.99% by weight, preferably 0 to 39.9% by weight, more preferably 0. ~ 29.5% by weight. Examples of the (meth) acrylic acid ester monomer, the crosslinkable monomer, and other copolymerizable monomers are the same as those exemplified in the above <monomer>. The crosslinkable monomer unit includes a carboxyl group-containing monomer unit, a halogen group-containing monomer unit, an epoxy group-containing monomer unit, and the like, 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 intended use, but is usually in the range of 10 to 150, preferably 20 to 100, and more preferably 25 to 60.

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

According to the present invention, there is provided a method for producing such an acrylic rubber and an acrylic rubber obtained by the production method.
In particular, according to the acrylic rubber of the present invention obtained by the above production method, pot stains do not occur during production, production can be performed with a high polymer recovery rate, storage stability is excellent, and when crosslinked. It is excellent in water resistance and compression set resistance. Here, in the field of rubber such as acrylic rubber, solidification is usually performed when solid rubber is obtained from a rubber solution or dispersion obtained by polymerization, and it is based on the findings of the present inventors. The characteristics of the obtained acrylic rubber change greatly depending on the state at the time of solidification.

On the other hand, the acrylic rubber of the present invention performs such coagulation in the presence of an alkylene oxide polymer using a metal sulfate as a coagulant. Here, the acrylic rubber obtained by such solidification contains an alkylene oxide polymer and a metal sulfate, but according to the findings of the present inventors, the acrylic rubber is simply alkylene. Since the oxide polymer and the metal sulfate are contained, the effect of improving the storage stability and the effect of improving the water resistance and the compression set resistance are not obtained, and the alkylene oxide polymer is not obtained at the time of solidification. It was found that it is necessary to use a metal sulfate as a coagulant in the presence of. The acrylic rubber of the present invention can be obtained only through such a coagulation method, and can be unequivocally specified by the wording that it simply contains an alkylene oxide polymer and a metal sulfate. It cannot be done.

Further, even if the internal state of the acrylic rubber of the present invention is analyzed by various analytical instruments, the acrylic rubber and the alkylene oxide polymer have carbon atoms and oxygen atoms as main components. , It is extremely difficult to specify the dispersed state of the alkylene oxide polymer and the metal sulfate, and 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 is characterized by containing the above-mentioned rubber component containing acrylic rubber and a cross-linking agent. The content of the acrylic rubber of the present invention in the rubber component may be selected according to the intended use, for example, usually 30% by weight or more, preferably 50% by weight or more, more preferably 70% by weight or more. , Particularly preferably 100% by weight.

As the rubber component, the acrylic rubber alone or in combination with the acrylic rubber and other rubbers can be used.
Other rubbers include acrylic rubbers other than the acrylic rubbers of the present invention, natural rubbers, polybutadiene rubbers, polyisoprene rubbers, styrene-butadiene rubbers, acrylonitrile-butadiene rubbers, silicon rubbers, fluororubbers, olefin elastomers, and styrene elastomers. Examples thereof include vinyl chloride-based elastomers, polyester-based elastomers, polyamide-based elastomers, polyurethane-based elastomers, and polysiloxane-based elastomers.

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 that does not impair the effects of the present invention, and is, for example, usually 70% by weight or less, preferably 50% by weight or less, and more preferably 30% by weight or less.

The cross-linking agent used in the rubber composition of the present invention is not particularly limited, and is, for example, a diamine compound, a polyvalent amine compound such as dithiocarbamic acid, and a carbonate thereof; a sulfur compound; a sulfur co-conductant; Conventionally known cross-linking agents such as compounds; organic carboxylate ammonium salts; organic peroxides; polyvalent carboxylic acids; isocyanuric acid compounds; organic peroxides; triazine compounds; can be used. Among these, a polyvalent amine compound and a triazine compound are preferable, and a polyvalent amine compound is particularly preferable.

Examples of the polyvalent amine compound include aliphatic polyvalent amine compounds such as hexamethylenediamine, hexamethylenediamine carbamate, and N, N'-dicinnamylidene-1,6-hexanediamine; 4,4'-methylenedianiline, p. -Phenylenediamine, m-Phenylenediamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-(m-Phenylenediisopropyridene) dianiline, 4,4'-(p-phenylenedi) Isopropylidene) dianiline, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 4,4'-diaminobenzanilide, 4,4'-bis (4-aminophenoxy) biphenyl, m-xyli Aromatic polyvalent amine compounds such as rangeamine, p-xylylenediamine, 1,3,5-benzenetriamine; 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 (an acrylic rubber containing a carboxyl group-containing monomer unit as a crosslinkable monomer unit).

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 And so on. These triazine compounds are particularly preferably used in combination with a halogen group-containing acrylic rubber (an acrylic rubber containing a halogen group-containing monomer unit as a crosslinkable monomer unit).

The organic carboxylic acid ammonium salt is, for example, ammonium benzoate, ammonium adipate; the dithiocarbamic acid compound is, for example, dimethyldithiocarbamic acid, zinc dimethyldithiocarbamate; the polyvalent carboxylic acid is, for example, tetradecanoic acid; isocyanuric acid. Examples of the compound include isocyanuric acid, ammonium isocyanurate: and the like. Among these, ammonium benzoate, dimethyldithiocarbamic acid, and isocyanuric acid are particularly suitable in combination with an epoxy group-containing acrylic rubber (an acrylic rubber containing an epoxy group-containing monomer unit as a crosslinkable monomer unit). Used for.

Each of these cross-linking agents can be used alone or in combination of two or more, and the blending amount thereof is usually 0.001 to 20 parts by weight, preferably 0.1 to 1 parts by weight, based on 100 parts by weight of the rubber component. It is 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 possible to make the mechanical strength of the rubber cross-linked product excellent while making the rubber elasticity sufficient, which is preferable.

The rubber composition of the present invention is suitable because the effect of the present invention can be highly improved by further adding a cross-linking accelerator. The cross-linking accelerator is not particularly limited, and is, for example, a guanidine-based cross-linking accelerator, a diazabicycloalkene-based cross-linking accelerator, an aliphatic secondary amine-based cross-linking accelerator, an aliphatic tertiary amine-based cross-linking accelerator, or dithiocarbamic acid. A salt-based vulcanization accelerator or the like can be mentioned as a suitable one. Among these, a guanidine-based cross-linking accelerator and a dithiocarbamate-based cross-linking accelerator are particularly preferable, and a guanidine-based cross-linking accelerator is more preferable.

Specific examples of the guanidine-based sulfide accelerator include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, and dicatecholbolate di-o-tolylguanidine. Salts, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine and the like can be mentioned, and 1,3-diphenylguanidine can be mentioned. 1,3-di-o-tolylguanidine and 1-o-tolylbiguanide are preferred because they are highly reactive, and 1,3-diphenylguanidine (DPG) is particularly preferred because it is more reactive.

Specific examples of the diazabicycloalkene-based vulcanization accelerator include 1,8-diazabicyclo [5.4.0] unde-7-sen and 1,5-diazabicyclo [4.3.0] no-5-nen. And so on.

Examples of the aliphatic secondary amine-based sulfide accelerator include dimethylamine, diethylamine, dipropylamine, diallylamine, diisopropylamine, di-n-butylamine, di-t-butylamine, di-sec-butylamine, and dihexylamine. Diheptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine, ditridecylamine, ditetradecylamine, dipentadecylamine, disetylamine, di-2-ethylhexylamine, dioctadecylamine, etc. it can.

Examples of the aliphatic tertiary amine-based sulfide accelerator include trimethylamine, triethylamine, tripropylamine, triallylamine, triisopropylamine, tri-n-butylamine, tri-t-butylamine, tri-sec-butylamine, and trihexyl. Examples thereof include amines, triheptylamines, trioctylamines, trinonylamines, tridecylamines, triundecylamines, and tridodecylamines.

Specific examples of the dithiocarbamate-based sulfide accelerator include zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc dipentyldithiocarbamate, zinc dihexyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, and N-ethyl. Zinc -N-phenyldithiocarbamate, zinc dibenzyldithiocarbamate, copper dipropyldithiocarbamate, copper diisopropyldithiocarbamate, copper dibutyldithiocarbamate, sodium diethyldithiocarbamate, sodium diisopropyldithiocarbamate, sodium dibutyldithiocarbamate, dimethyldithiocarbamate second Examples include iron 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 cross-linking accelerator used in the present invention, other cross-linking accelerators other than the above can also be used. Examples of other cross-linking accelerators include N-cyclohexyl-2-benzothiazolesulfenamide, N-tert-butyl-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, and the like. N-Oxyethylene-2-benzothiazolesulfenamide, N. Sulfenamide-based vulcanization accelerators such as N-diisopropyl-2-benzothiazole sulfenamide; Thiourea-based vulcanization accelerators such as diethylthiourea; 2-mercaptobenzothiazole, dibenzothiazildisulfide, 2-mercaptobenzothiazole zinc Thiazol-based vulcanization accelerators such as salts; Xanthogenic acid-based vulcanization accelerators such as sodium isopropylxanthogenate, zinc isopropylxanthogenate, zinc butylxanthogenate; thiuram-based vulcanizations such as tetramethylthium monosulfide and tetramethylthiuram disulfide Accelerators; imidazole-based vulcanization accelerators such as 2-methylimidazole and 2-phenylimidazole; quaternary onium salt-based vulcanization accelerators such as tetra n-butylammonium bromide and octadecyltri n-butylammonium bromide; triphenyl Tertiary phosphine-based vulcanization accelerators such as phosphine and tri-p-tolylphosphine; and the like.

These cross-linking accelerators can be used alone or in combination of two or more, and the blending amount thereof is usually 0.01 to 20 parts by weight, preferably 0, with respect to 100 parts by weight of the rubber component. It is 1 to 10 parts by weight, more preferably 1 to 5 parts by weight. When the content of the cross-linking accelerator is in this range, the tensile strength and compression set resistance of the obtained rubber cross-linked product can be further improved, which is preferable.

The rubber composition of the present invention is suitable because the crosslinked physical properties are improved by further adding an anti-scorch agent. The scorch inhibitor is not particularly limited, but for example, an imide compound such as N-cyclohexylthiophthalimide, an alkylamine alkylphenol compound, a hydroquinone / quinone compound, and 2,4-di (3-isopropylphenyl) -4-methyl. -1-Pentene and the like can be mentioned, and an imide compound is preferable.

These scorch inhibitors 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, based on 100 parts by weight of the rubber component. It is in the range of ~ 1 part by weight, more preferably 0.1 to 0.5 part by weight.

The rubber composition of the present invention is suitable because the effect of the present invention is more highly improved by further containing an antiaging agent.

The anti-aging agent is not particularly limited, but for example, 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-) Methylbenzyl-p-cresol), 4,4'-methylenebis (2,6-di-t-butylfunol), 2,2'-methylene-bis (4-methyl-6-t-butylphenol), 3- (3) , 5-Di-tert-butyl-4-hydroxyphenyl) Phenolic antioxidants that do not contain sulfur atoms such as stearyl propionate, alkylated bisphenol, and butylation reaction products of p-cresol and dicyclopentadiene; 2, 4-bis [(octylthio) methyl] -6-methylphenol, 2,2'-thiobis- (4-methyl-6-t-butylphenol), 4,4'-thiobis- (6-t-butyl-o-) Cresol), 2,6-di-t-butyl-4- (4,6-bis (octylthio) -1,3,5-triazine-2-ylamino) phenols and other thiophenolic anti-aging agents; tris (nonyl) Phenyl) Phosphite, diphenylisodecylphosphite, tetraphenyldipropylene glycol diphosphite and other phosphite ester-based anti-aging agents; sulfur ester-based anti-aging agents such as dilauryl thiodipropionate; phenyl-α-naphthylamine, phenyl- β-naphthylamine, p- (p-toluenesulfonylamide) -diphenylamine, 4,4'-(α, α-dimethylbenzyl) diphenylamine, N, N-diphenyl-p-phenylenediamine, N-isopropyl-N'-phenyl Amine-based anti-aging agents such as -p-phenylenediamine, butylaldehyde-aniline condensate; imidazole-based anti-aging agents such as 2-mercaptobenzimidazole; 6-ethoxy-2,2,4-trimethyl-1,2-dihydro Examples thereof include quinoline-based anti-aging agents such as quinolin; and hydroquinone-based 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. As described above, the antiaging agent can be contained in the emulsion polymerization solution before coagulation in advance.

As the rubber composition of the present invention, those further containing a filler can be preferably used. The filler is not particularly limited, and examples thereof include a reinforcing filler and a non-reinforcing filler, and a reinforcing filler is preferable.

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; and the like. Examples of the non-reinforcing filler include quartz powder, silica soil, zinc flower, basic magnesium carbonate, activated calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, aluminum sulfate, calcium sulfate, barium sulfate and the like. be able to.

Each of these fillers can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range that does not impair the effects of the present invention, and is usually used with respect to 100 parts by weight of the rubber component. It is in the range of 1 to 200 parts by weight, preferably 10 to 150 parts by weight, and more preferably 20 to 100 parts by weight.

It is preferable that the rubber composition of the present invention further contains a silane coupling agent. The silane coupling agent that can be used is not particularly limited, but for example, 3-methacryloxypropyltrimethoxysilane, bis (3- (triethoxysilyl) propyl) disulfide, and bis (3-triethoxysilylpropyl) tri. Propyl, Bis (3- (triethoxysilyl) propyl) tetrasulfide, γ-mercaptopropyltriethoxysilane, 3- [ethoxybis (3,6,9,12,15-pentaoxaoctacosan-1-yloxy) silyl] -1-Propylthiol, 3-octanoylthio-1-propyl-triethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, γ-trimethoxysilylpropylbenzothiadyltetrasulfide, 3-tri Methoxysilylpropylbenzothiazole tetrasulfide, 3-thiocyanatepropyltriethoxysilane, vinyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, 3-trimethoxysilylpropylmethacrylate monosulfide, γ- Examples thereof include glycidoxypropyltriethoxysilane, 3-nitropropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.

Each of 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. It is in the range of 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 the above-mentioned cross-linking agent and other compounding agents other than the cross-linking accelerator, the scorch inhibitor, the filler and the silane coupling agent, which are used as needed. 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 tars and castor oils. Softeners such as calcium stearate, light stabilizers, processing aids, adhesives, lubricants, flame retardants, mold proofing agents, antistatic agents, colorants, cross-linking retardants, polyolefin resins, polystyrene resins, polyacrylic resins , Polyphenylene ether-based resin, polyester-based resin, polycarbonate-based resin, polyamide resin, vinyl chloride resin, fluororesin and other resins. These other compounding agents can be used alone or in combination of two or more, and the compounding amount thereof is appropriately selected within a range that does not impair the effects of the present invention.

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

The compounding procedure may be carried out by a normal procedure performed in the field of polymer processing. For example, it is a component that is easily reacted or decomposed by heat after sufficiently mixing components that are difficult to react or decompose by heat. It is preferable to mix the cross-linking agent or the like at a temperature at which reaction or decomposition does not occur in a short time.

[Rubber crosslinked product]
The rubber crosslinked product of the present invention is obtained by cross-linking the above rubber composition.
The crosslinked rubber product of the present invention is formed by using the rubber composition of the present invention and molded by a molding machine corresponding to a desired shape, for example, an extruder, an injection molding machine, a compressor, a roll, or the like, 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, cross-linking may be performed after molding in advance, or cross-linking may be performed at the same time as molding. The molding temperature is usually 10 to 200 ° C, preferably 25 to 150 ° C. The cross-linking temperature is usually 100 to 250 ° C., preferably 130 to 220 ° C., more preferably 150 to 200 ° C., and the cross-linking time is usually 0.1 minutes to 10 hours, preferably 1 minute to 5 hours. As the heating method, a method used for cross-linking rubber such as press heating, steam heating, oven heating, and hot air heating may be appropriately selected.

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

The crosslinked rubber product of the present invention has excellent compression resistance to permanent strain and water resistance while maintaining basic characteristics as a rubber such as tensile strength, elongation, and hardness. The compression set of the rubber crosslinked product of the present invention measured in accordance with JIS K6262 is appropriately selected depending on the intended use, but is usually 1 to 50, preferably 5 to 30, more preferably 10 to 20. Is the range of.

The rubber crosslinked product of the present invention makes use of the above characteristics, for example, O-ring, packing, diaphragm, oil seal, shaft seal, bearing seal, mechanical seal, well head seal, seal for electric / electronic equipment, air compression equipment. Sealing materials such as seals for seals; rocker cover gaskets attached to the connection between the cylinder block and the cylinder head, oil pan gaskets attached to the connection between the oil pan and the cylinder head or the transmission case, positive electrode, electrolyte plate and negative electrode. Various gaskets such as fuel cell separator gaskets and hard disk drive top cover gaskets mounted between a pair of housings that sandwich a unit cell equipped with; cushioning material, anti-vibration material; wire coating material; industrial belts; tubes -Preferably used as hoses; sheets; etc.

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

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

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

[Acrylic rubber recovery rate]
The ratio of the weight of the dried solid acrylic rubber obtained by the polymerization to the rubber solid content in the emulsion polymerization solution after the polymerization was determined and evaluated according to the following criteria.
⊚: 100%
◯: Over 95%, less than 100% Δ: Over 90%, 95% or less ×: Over 70%, 90% or less × ×: 70% or less

[Pottle dirt]
The pot stain was judged by observing the solidification tank after solidification and using the following criteria.
◎: No dirt on the coagulation tank and stirring blade ○: Slight dirt on the coagulation tank and stirring blade ×: White deposits on the entire tank × ×: Thick white deposits on the entire tank Difficult to clean

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

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

[Moony Scoach Exam]
For the acrylic rubber composition, the Mooney scorch was measured under the measurement conditions of 125 ° C. according to JIS K6300, and the Mooney scorch time was t5 (minutes), the Mooney scorch time was t35 (minutes), and the Mooney viscosity (ML1 + 4, 100 ° C.). The lowest value Vmin was measured. In this measurement, the time when the Mooney viscosity increased by 5 M from Vmin was defined as t5, and the time when the Mooney viscosity increased by 35 M from Vmin was defined as t35. The larger the values of t5 and t35, the longer it takes to vulcanize, and it can be judged that the rubber composition has excellent storage stability and the vulcanization promoting effect is suppressed (well controlled). .. The lower the value of Vmin, the smaller the initial vulcanization of the rubber composition, and it can be judged that the storage stability is excellent.

[Example 1]
In a mixing container equipped with a homomixer, 46.294 parts of pure water, 49.3 parts of ethyl acrylate, 49.3 parts of n-butyl acrylate, 1.4 parts of mono-n-butyl fumarate, as an anionic emulsifier. Sodium lauryl sulfate (trade name "Emar 2FG", manufactured by Kao Corporation) 0.567 parts, and polyoxyethylene dodecyl ether as a nonionic emulsifier (trade name "Emargen 105", weight average molecular weight: about 1500, manufactured by Kao Corporation) A monomeric emulsion was obtained by charging 1.4 parts and stirring.

Next, 170.853 parts of pure water and 2.98 parts of the monomer emulsion obtained above were put into a polymerization reaction tank equipped with a thermometer and a stirrer, and the temperature was 12 ° C. under a nitrogen stream. Cooled down to. Next, in the polymerization reaction tank, 145.85 parts of the monomer emulsion obtained above, 0.00033 parts of ferrous sulfate as a reducing agent, 0.264 parts of sodium ascorbate as a reducing agent, and , 7.72 parts of a 2.85 wt% potassium persulfate aqueous solution as a polymerization initiator (0.22 parts as the amount of potassium persulfate) was continuously added dropwise over 3 hours. After that, the reaction was continued for 1 hour while the temperature in the polymerization reaction tank was kept at 23 ° C., it was confirmed that the polymerization conversion rate reached 95%, and hydroquinone as a polymerization terminator was added for polymerization. The reaction was stopped to obtain an emulsion polymerization solution.

Then, with respect to 100 parts of the emulsion polymerization solution obtained by polymerization, stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (trade name "Irganox 1076", BASF) as an antioxidant was added. 0.3 parts (total of the monomers charged in producing the emulsion polymerization solution (that is, the total of ethyl acrylate, n-butyl acrylate, and mono n-butyl fumarate)) 1 part), 0.011 part of ethylene oxide polymer (polyethylene glycol, weight average molecular weight (Mw) = 100,000) (for a total of 100 parts of the prepared monomers used in producing the emulsion polymerization solution) 0.039 parts) and polyoxyethylene stearyl ether phosphoric acid as a lubricant (trade name "Phosphanol RL-210", weight average molecular weight: about 500, manufactured by Toho Chemical Industry Co., Ltd.) 0.075 parts (emulsion polymerization solution) A mixed solution was obtained by mixing (0.25 parts) with respect to a total of 100 parts of the charged monomers used in the production of. Then, the obtained mixed solution is transferred to a coagulation tank, 60 parts of industrial water is added to 100 parts of this mixed solution, the temperature is raised to 85 ° C., and then the mixed solution is stirred at a temperature of 85 ° C. However, by continuously adding 3.3 parts of sodium sulfate as a coagulant (11 parts with respect to 100 parts of the polymer contained in the mixed solution), the polymer was coagulated, whereby the water-containing crumb of acrylic rubber was coagulated. Got

Next, 388 parts of industrial water was added to 100 parts of the solid content of the hydrous crumb obtained above, and the mixture was stirred at 15 ° C. for 5 minutes in the coagulation tank, and then the water was discharged from the coagulation tank. The hydrous 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 parts of concentrated sulfuric acid was added to 100 parts of the solid content of the hydrous crumb washed with water as described above, and in the coagulation tank. After stirring at 15 ° C. for 5 minutes, the hydrous crumb was pickled by discharging water from the coagulation tank. Next, 388 parts of pure water was added to 100 parts of the solid content of the water-containing crumb that had been pickled, and after stirring at 15 ° C. for 5 minutes in the coagulation tank, water was discharged from the coagulation tank to contain water. The crumb was washed with pure water, and the water-containing crumb that had been washed with pure water was dried at 110 ° C. for 1 hour with a hot air dryer to obtain a solid acrylic rubber (A1). The conditions of these manufacturing processes are shown in Table 1.

The obtained acrylic rubber (A1) has a Mooney viscosity (ML1 + 4, 100 ° C.) of 31, a recovery rate of 100%, and a composition of 49.3% by weight of ethyl acrylate and 49.3 by weight of n-butyl acrylate. By weight%, mono-n-butyl fumarate unit was 1.4% by weight. These results are shown in Table 2.

Further, for the acrylic rubber (A1), the recovery rate of the polymer was measured, and the stains on the pot of the polymerization tank after the polymerization were observed, and the results are shown in Table 1.

Using a Banbury mixer, 100 parts of the obtained acrylic rubber (A1), 30 parts of clay (trade name "Satinton Clay 5A", manufactured by Takehara Chemical Industry Co., Ltd., calcined kaolin), silica (trade name "Carplex 1120"). , 15 parts made by Evonik, silica (trade name "Carplex 67", made by Evonik) 35 parts, stearic acid 2 parts, ester wax (trade name "Grec G-8205", manufactured by Dainippon Ink and Chemicals Co., Ltd.) ) 1 part, 4,4'-bis (α, α-dimethylbenzyl) diphenylamine (trade name "Nocrack CD", manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.) 2 parts, and 3-methacryloxypropyltrimethoxysilane (trade name) 1 part of "KBM-503" (manufactured by Shinetsu Silicone Co., Ltd., silane coupling agent) was added and mixed at 50 ° C. for 5 minutes. The resulting mixture was then transferred to a roll at 50 ° C. to 0.6 parts of hexamethylenediamine carbamate (trade name "Diak # 1", manufactured by DuPont Dow Elastomer, aliphatic polyvalent amine compound), and 1,3. A rubber composition was obtained by blending two parts of -di-o-tolylguanidine (trade name "Noxeller DT", manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., a cross-linking accelerator) and kneading them.
Water resistance was measured using the obtained rubber composition, and the results are shown in Table 1.

[Example 2]
A solid acrylic rubber (A2) was obtained in the same manner as in Example 1 except that 3.3 parts of sodium sulfate as a coagulant was changed to 3.3 parts of magnesium sulfate.

In the same manner as in Example 1, the pot stains and the like in the polymerization tank were observed, the polymer recovery rate and water resistance were measured, and the results are shown in Table 1. In addition, the Mooney viscosity (ML1 + 4, 100 ° C.) and monomer composition of acrylic rubber (A2) were measured, and the results are shown in Table 2.

[Example 3]
0.3 part of stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate as an anti-aging agent is 2,4-bis [(octylthio) methyl] -6-methylphenol (trade name) Solid acrylic rubber (A3) was obtained in the same manner as in Example 1 except that "Irganox 1520L" (manufactured by BASF) was changed to 0.3 part.

In the same manner as in Example 1, the pot stains and the like in the polymerization tank were observed, the polymer recovery rate and water resistance were measured, and the results are shown in Table 1. In addition, the Mooney viscosity (ML1 + 4, 100 ° C.) and monomer composition of acrylic rubber (A3) were measured, and the results are shown in Table 2.

[Example 4]
A solid acrylic rubber (A4) was obtained in the same manner as in Example 3 except that the number of washings with water was changed from 4 to 2.

In the same manner as in Example 1, the pot stains and the like in the polymerization tank were observed, the polymer recovery rate and water resistance were measured, and the results are shown in Table 1. In addition, the Mooney viscosity (ML1 + 4, 100 ° C.) and monomer composition of acrylic rubber (A4) were measured, and the results are shown in Table 2.

[Example 5]
A solid acrylic rubber (A5) was obtained in the same manner as in Example 3 except that the number of washings with water was changed from 4 to 1.

In the same manner as in Example 1, the pot stains and the like in the polymerization tank were observed, the polymer recovery rate and water resistance were measured, and the results are shown in Table 1. In addition, the Mooney viscosity (ML1 + 4, 100 ° C.) and monomer composition of acrylic rubber (A5) were measured, and the results are shown in Table 2.

[Example 6]
The timing of adding the ethylene oxide polymer was changed to the timing of preparing the monomer emulsion, and the amount of ethylene oxide polymer added was based on 100 parts of the total amount of the prepared monomers used in producing the emulsion polymer. A solid acrylic rubber (A6) was obtained in the same manner as in Example 1 except that the amount was 0.039 parts.

In the same manner as in Example 1, the pot stains and the like in the polymerization tank were observed, the polymer recovery rate and water resistance were measured, and the results are shown in Table 1. In addition, the Mooney viscosity (ML1 + 4, 100 ° C.) and monomer composition of acrylic rubber (A6) were measured, and the results are shown in Table 2.

[Comparative Example 1]
A solid acrylic rubber (B1) was obtained in the same manner as in Example 3 except that 0.011 part of the ethylene oxide polymer used in the solidification operation was not used.

In the same manner as in Example 1, the pot stains and the like in the polymerization tank were observed, the polymer recovery rate and water resistance were measured, and the results are shown in Table 1. The Mooney viscosity (ML1 + 4, 100 ° C.) of acrylic rubber (B1) is 33, the recovery rate is 100%, and the composition is 49.3% by weight of ethyl acrylate and 49.3% by weight of n-butyl acrylate. %, Mono n-butyl fumarate unit was 1.4% by weight.

[Comparative Example 2]
The amount of sodium lauryl sulfate used as an anionic surfactant was 0.567 to 0.709 parts, and the amount of polyoxyethylene dodecyl ether used as a nonionic surfactant was 1.4 to 1.82 parts. A solid acrylic rubber (B2) was obtained in the same manner as in Comparative Example 1 except that the respective changes were made.

In the same manner as in Example 1, the pot stains and the like in the polymerization tank were observed, the polymer recovery rate and water resistance were measured, and the results are shown in Table 1. The Mooney viscosity (ML1 + 4, 100 ° C.) of acrylic rubber (B2) is 33, the recovery rate is 100%, and the composition is 49.3% by weight of ethyl acrylate and 49.3% by weight of n-butyl acrylate. %, Mono n-butyl fumarate unit was 1.4% by weight.

[Comparative Example 3]
A solid acrylic rubber (B3) was obtained in the same manner as in Comparative Example 2 except that the number of washings with water was changed from 4 to 1.

In the same manner as in Example 1, the pot stains and the like in the polymerization tank were observed, the polymer recovery rate and water resistance were measured, and the results are shown in Table 1. The Mooney viscosity (ML1 + 4, 100 ° C.) of acrylic rubber (B3) is 33, the recovery rate is 100%, and the composition is 49.3% by weight of ethyl acrylate and 49.3% by weight of n-butyl acrylate. %, Mono n-butyl fumarate unit was 1.4% by weight.

[Comparative Example 4]
A solid acrylic rubber (B4) was obtained in the same manner as in Comparative Example 1 except that the amount of sodium sulfate used as a coagulant used in the coagulation operation was changed from 3.3 parts to 10 parts.

In the same manner as in Example 1, the pot stains and the like in the polymerization tank were observed, the polymer recovery rate and water resistance were measured, and the results are shown in Table 1. The Mooney viscosity (ML1 + 4, 100 ° C.) of acrylic rubber (B4) is 33, the recovery rate is 100%, and the composition is 49.3% by weight of ethyl acrylate and 49.3% by weight of n-butyl acrylate. %, Mono n-butyl fumarate unit was 1.4% by weight.

[Comparative Example 5]
A solid acrylic rubber (B5) was obtained in the same manner as in Comparative Example 4 except that the number of washings with water was changed from 4 to 1.

In the same manner as in Example 1, the pot stains and the like in the polymerization tank were observed, the polymer recovery rate and water resistance were measured, and the results are shown in Table 1. The Mooney viscosity (ML1 + 4, 100 ° C.) of acrylic rubber (B5) is 33, the recovery rate is 100%, and the composition is 49.3% by weight of ethyl acrylate and 49.3% by weight of n-butyl acrylate. %, Mono n-butyl fumarate unit was 1.4% by weight.

（※１）老化防止剤１は、３−（３，５−ジ−ｔｅｒｔ−ブチル−４−ヒドロキシフェニル）プロピオン酸ステアリル
（※２）老化防止剤２は、２，４−ビス［（オクチルチオ）メチル］−６−メチルフェノール
（※３）ポリエチレンオキシド重合体は、ポリエチレングリコール
（※Ａ）単量体乳化液作製のための配合剤の添加量は、仕込み単量体１００部に対する配合量で示した。
（※Ｂ）凝固前の乳化重合液に添加した配合剤の添加量は、乳化重合液１００部に対する配合量で示した。
（※Ｃ）凝固工程で使用した凝固剤の添加量は、乳化重合液に、老化防止剤、ポリエチレンオキシド、および／または滑剤を添加することにより得られた混合液１００部に対する配合量で示した。

(* 1) Anti-aging agent 1 is stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (* 2) Anti-aging agent 2 is 2,4-bis [(octylthio) Methyl] -6-methylphenol (* 3) For polyethylene oxide polymer, the amount of compounding agent added for preparing polyethylene glycol (* A) monomer emulsion is indicated by the amount to be added to 100 parts of the charged monomer. It was.
(* B) The amount of the compounding agent added to the emulsion polymerization solution before coagulation is shown as the amount to be added to 100 parts of the emulsion polymerization solution.
(* C) The amount of the coagulant used in the coagulation step is shown as the amount to be added to 100 parts of the mixed solution obtained by adding an antiaging agent, polyethylene oxide, and / or a lubricant to the emulsion polymerization solution. ..

From Table 1, all of the methods for producing acrylic rubber solidified with sodium sulfate or magnesium sulfate in the presence of the ethylene oxide polymer of the present invention show that the polymer can be recovered with high efficiency without causing pot stains during production. It can be seen that the water resistance (volume change rate before and after immersion) when the obtained acrylic rubber is crosslinked is in the range of 15 to 29%, which is very good (Examples 1 to 6). On the other hand, in the production of acrylic rubber solidified in the absence of an ethylene oxide polymer, it can be seen that at least one of the properties of pot stain, polymer recovery rate and water resistance is extremely poor (Comparative Examples 1 to 5).

From Table 1, only the ethylene oxide polymer was removed from Example 3, but when solidified without the presence of the ethylene oxide polymer, the pot was heavily soiled and the whole pot had a thick and fine scale. It can be seen that the polymer recovery rate is as high as 50% (Comparative Example 1). In order to eliminate the pot stain of Comparative Example 1, the amount of the emulsifier used can be increased from 0.567 parts and 1.4 parts to 0.709 parts and 1.82 parts, respectively, to eliminate the pot stain, but the polymer. It can be seen that the recovery rate has been terrible and the water resistance has deteriorated (Comparative Example 2). It can be seen that when the number of cleanings in Comparative Example 2 is set to 1, the water resistance becomes extremely poor and the number of cleanings has an effect (Comparative Example 3). On the other hand, the notation of the number of cleanings in Table 1 is for the initial cleaning, and in reality, the acid cleaning and the water cleaning are performed once after that. In the conventional method for producing acrylic rubber, neither acid cleaning nor subsequent water cleaning is performed, and water cleaning is usually performed once, and it can be seen that the water resistance of the acrylic rubber obtained by the conventional manufacturing method is inferior. .. Next, when the amount of the coagulant was increased from 3.3 parts to 10 parts to eliminate the polymer recovery rate, it was found that the pot stain was deteriorated and the water resistance was also deteriorated (Comparative Example 4). In Comparative Example 5, the initial number of cleanings of Comparative Example 4 was changed from 4 to 1, and the water resistance was extremely deteriorated as in the relationship between Comparative Examples 2 and 3 (Comparative Example 5). An example in which the amount of both the emulsifier and the coagulant is increased is not shown, but it can be expected that the water resistance is very poor.

From the data in Table 1, the effect of the ethylene oxide polymer is that the activity of the emulsifier can be enhanced and the addition of the emulsifier can be reduced, the coagulation activity of the coagulant can be enhanced and the addition of the coagulant can be reduced, and ethylene oxide can be added. The amount of the polymer added (0.011 part) is two orders of magnitude smaller than the amount of the emulsifier or lubricant added, and the remaining amount of the resulting acrylic rubber is reduced to significantly improve water resistance. It seems to be improving.

From Table 1, it can be seen that the effect of the present invention is not impaired even if the ethylene oxide polymer is added before the polymerization (Example 6).
From Table 1, when the initial number of washings was 4 times (Example 3), 2 times (Example 4), and 1 time (Example 5), the comparative examples (Comparative Example 2, Comparative Example 3, and Comparative Example 4) Similar to Comparative Example 5), the number of washings has an effect on water resistance, but it can be seen that the effect is smaller in Examples 3 to 5 than in Comparative Examples 2 to 5. It is considered that this is because the ethylene oxide polymer has an effect of improving water resistance even before washing in the examples.

[Examples 7 to 12]
Using the rubber compositions obtained in Examples 1 to 6, a compression set and a Mooney scorch test were performed, and the results are shown in Table 2.

表２より、本発明の製造方法で製造されたアクリルゴムは、いずれも、常態物性に優れ、架橋した時の圧縮永久歪み性（圧縮永久歪率が低く）及び貯蔵安定性に優れることがわかる（実施例７〜１２）。

From Table 2, it can be seen that all of the acrylic rubbers produced by the production method of the present invention are excellent in normal physical properties, compressive permanent distortion (low compression permanent strain rate) and storage stability when crosslinked. (Examples 7 to 12).

Claims (6)

An emulsion polymerization step in which a monomer containing a (meth) acrylic acid ester as a main component is emulsion-polymerized in the presence of an emulsifier using a polymerization catalyst to obtain an emulsion polymerization solution.
A coagulation step in which the emulsion polymerization solution is brought into contact with a metal sulfate in the presence of an alkylene oxide polymer and coagulated to obtain a hydrous crumb.
A cleaning step for cleaning the hydrous crumb and
A drying step of drying the washed hydrous crumb, and
A method of manufacturing acrylic rubber. The method for producing acrylic rubber according to claim 1, wherein the polymerization initiator as the polymerization catalyst is a combination of a peroxide, ferrous sulfate, ascorbic acid and / or ascorbic acid salt. By adding the alkylene oxide polymer to the monomer emulsion before emulsion polymerization and / or to the emulsion polymerization solution after emulsion polymerization, the alkylene oxide polymer is added to the emulsion polymerization solution at the time of solidification. The method for producing acrylic rubber according to claim 1 or 2, wherein The method for producing acrylic rubber according to any one of claims 1 to 3, wherein the weight average molecular weight (Mw) of the alkylene oxide polymer is in the range of 10,000 to 6,000,000. The contact between the emulsion polymerization solution and the metal sulfate is either by adding the metal sulfate to the emulsion polymerization solution or by adding the emulsion polymerization solution to the solution or dispersion of the metal sulfuric acid. The method for producing acrylic rubber according to any one of claims 1 to 4. The method for producing acrylic rubber according to any one of claims 1 to 5, wherein the cleaning in the cleaning step includes acid cleaning.